Academy of Sciences of the USSR Academy of Sciences of the UzbekSSR + Sf; ACTINBDES-89
INTERNATIONAL CONFERENCE
Tashkent, USSR September 24-29.1989
ABSTRACTS Academy of Sciences of the USSR Academy of Sciences of the UzbekSSR ACTINIDES-89 INTERNATIONAL CONFERENCE
Tashkent, USSR September 24-29,1989
ABSTRACTS
e Moscow «NAUKA» 1989 INTERNATIONAL CONFERENCE "ACTINIDES-S9
ABSTRACTS:
PLENARY LECTURES
1. LARGE SCALE PRODUCTION AND APPLICATION, SYNTHESIS OF SUPERHEAVY ELEMENTS IN REACTIONS WITH HEAVY IONS
2. ELECTRONIC STRUCTURE AND SPECTROSCOPY
3. THERMODYNAMIC PROPERTIES
4. SOLID STATE PHYSICS AND CHEMISTRY
5. SOLUTION CHEMISTRY
6. ANALYTICAL CHEMISTRY
7. ACTINIDES IN ENVIRONMENT
© Vernadeky Institute of Geochemistry and Analytical Chemiatry of the Academy of
ISBN 5-02-007142-7 Scieneea of the USSR, i989 PREFACE
STUDIES ON ACTINIDE ELEMENTS ARE IN PROGRESS IN MANY COUNTRIES FROM ALL OVER THE WORLD. THE RESULTS FROM A GREAT SCIENTIFIC INTEREST PAYED TO THESE ELEMENTS, PHYSICAL AND CHEMICAL PROPERTIES OF WHICH HAVE NOT BEEN INVESTIGA TED WELL ENOUGH; AND FROM A NECESSITY TO DEVELOP MORE EFFICIENT AND SIMPLE METHODS OF THEIR ISOLATION AND DETERMINATION, AND WIDE POSSIBILITIES OF THEIR PRACTICAL USE. SUCH APPLICATIONS OF THESE ELEMENTS SHOULD BE NOTED AS PORTABLE SOURCES OF ENERGY, POWERFUL AND COMPACT NEUTRON SOURCES AND SO ON. INTEREST IN THESE ELEMENTS IS ALSO CAUSED BY A CONTINUING DEVELOPMENT OF ATOMIC ENERGETICS AND THE PROBLEM OF HARMLESS WASTE DISPOSAL ASSOCIATED WITH THE LATTER, GENERAL RESULTS OF ACTIN1DE STUDIES ARE REGULARLY DISCUSSED AT INTERNATIO NAL CONFERENCES. THE TWO PRECEDING CONFERENCES HAVE BEEN HELD IN PACIFIC GROVE (USA, CALIFORNIA, "ACTINIDES 81") AND AIX EN PROVENCE (FRANCE, "ACTI- NIDES 85" THE PRESENT BOOK CONTAINS EXTENDED ABSTRACTS OF PAPERS PRESENTED AT THE "ACTINIDES 89" INTERNATIONAL CONFERENCE (USSR, TASHKENT, SEPTEMBER 24 - 29 !, SCIENTIFIC PROGRAMME OF THE CONFERENCE INCLUDES 9 INVITED PLENARY LECTURES AND 12 INVITED KEYNOTE LECTURES ON THE MOST ACTUAL TRENDS OF STU DIES, MORE THAN 60 ORAL COMMUNICATIONS AND SOME 200 POSTERS. THE ABSTRACTS HAVE BEEN ARRANGED IN CERTAIN LOGICAL SEQUENCE CORRESPON DING TO THEIR SCIENTIFIC SUBJECT MATTER. THE NUMBER OF A COMMUNICATION IN THIS BOOK CORRESPONDS. TO ITS NUMBER IN THE PROGRAMME OF THE CONFERENCE TO МАХЕ IT EASIER TO FIND A NEEDED ABSTRACT. THE LARGER PART OF ABSTRACTS HAVE BEEN PRINTED WITHOUT ANY CHANGES, AS THEY WERE PRESENTED, IN PARTICULAR CASES, IF A MATERIAL DID NOT SATISFY THE REQUESTED DEMANDS, THE ABSTRACTS WERE EDITED AND RETYPED. UNFORTU NATELY, WE HAD NO OPPORTUNITIES TO SUBMIT CORRECTED TEXTS FOR APPROVAL OF THE AUTHORS BECAUSE OF LACK OF TIME, THEREFORE, WE APOLOGIZE FOR POSSIBLE INCONSISTENCIES, SELECTION OF THE PAPERS HAS BEEN CARRIED OUT BY THE PROGRAMME COMIS- S10N OF THE ORBANIZING COMMITTEE, PERSONALLY BY PROF, B.F. MYASOEDOV, PROF, A.II. ROZEN AND DR, G.V, IONOVA, ESPECIALLY LARGE WORK TO PREPARE ABSTRACTS FOR PUBLICATION AND TO MAKE UP THE PROGRAMME HAS BEEN DONE BY DR, M.K, CHMU- TOVA.
PROF. A.S. NIKIFOROV PROF. B.F. HYASOEDOV
•V JiTW- ACTINIDES-89 INTERNATIONAL ADVISORY COMMITTEE
PROF, T.BRAUN (HUNGARY) PROF W.MllLLER (C.E.CJ. PROF, G.R.CHOPPIN (USA) PROF S.NIESE (GDR) PROF, P.R.DANESI (IAEA) PROF R.PASCARD (FRANCE) PROF. N.EDELSTEIN (USA) PROF, W.SUSKI (POLAND) PROF. P.ERDOS (SWITZERLAND) PROF, T.TOMINAGA (JAPAN) PROF. J.FUGER (CE.C,J,R.C.,KARLSRUHE) PROF D,-X.WANG (CHINA) PROF. LGRENTHE (SWEDEN) PROF P.VIGATO (ITALY) PROF. G, HERRMANN (FRG)
CONFERENCE COMMITTEE
PROF, A.P.ALEXANDROV - CHAIRMAN PROF. P.K.KHABIBULLAEV- CO-CHAIRMAN PROF. A.S.NIKIFOROV - VICE--CHAIRMAN PROF. A.A.KIST VICE--CHAIRMAN PROF. B.F.MYASOEDOV - VICE--CHAIRMAN DR. '.A.LEBEDEV SCIENTIFIC SECRETARY
DR. G.A.NEKRASOVA DR, A.S.POLYAKOV PROF. V.V.GROHOV PROF. A.M. ROZEN DR, B.S.ZAKHARKIN PROF, D.I.SKOROVAROV PROF. A.P.ZAKHAROV PROF. O.V.SKIBA PROF. A.M.CHEKMAREV PROF. D.N.SUGLOBOV PROF, I.I.ZVARA PROF. G.N.FLEROV PROF. V.S. KOLTUNOV PROF. A.V.FOKIN PROF. N.N.KROT PR. V.YA.FRENKEL DR, A.K.KRUGLQV PROF, V.A.TSYKANOV DR, L.N.I.AZAREV PROF, N.T.CHEBOTAREV PROF. B.N.LASKORIN MRS. N.V.SHAKHOVA PROF, B.P.NIKOLSKY MRS. E.P.SHUMILOVA PROF, YU.TS.OGANESYAN DR. I.K.SHVETSOV PLENARY LECTURES
# ACMHIDE ACCUHULAMOS AND RABIOCHEHICAb PROBLEMS , A.S.Hikiforov, A.li.Roaen. All-union Research Institute of Inorganic Materials, Mosoow, USSR With nuclear power development increasingly sore aotlnides - plutoslum, neptunium end transplutonlum elements (IPS) are being produced. Plutonium oan be used In a nuclear fuel cyole to produce nixed uranium- plutonium fuel for fast and thermal reaotors. The fuel cycle «1th thl3 ele ment Is closed* * more complicated problem la a management of Hp and TPE that accumulate in significant amounts. Beptunium-237 and аоег101ии-г41 can be employed to produce plutonium-238 - a good material for neat and current sources ( ™Pu produced from "Am can be employed in medicine). Calif ornlum-252, curium-244 and 242, aserioius-241 are used to produce neutron, alpha- and gamma sour ces as well as neat, e.g., at the Research Institute of Atomic Reac tors (RIAR) , see the review of V.'.Isykanov and coworkers [l]. Howe ver the isotopes will be more widely used with reprocessing Improvements and cost reduotion their amount used up is lefts than that accumulated* Hence, the problem of TPE storage arises. To solve it one must proceed from the fact that due to their long half-life their disposal into the ground is not per missible. Since the master line of high level waste management is solidifica tion and the TPE incorporation into matrices will not practically allow their future use it seems advisable to isolate these elements at one of the stages of spent fuel reprocessing. Therefore, along with spent nuclear fuel reproces sing Improvements three more radiochemical problems arise, vie., a thorough actinide extraction from radiochemical process wastes, actinide separation and finally storage* Improvement of extraction process. On mixed fuel reprocessing with IB? and at high plutonium concentrations the limited solubility of TBP-Pu solvate in saturated hydrocarbons entails the danger of a second organio phase formation. To avoid this instead of TBP phosphates with the optimized hydrocarbon chaln- an elongated one with an isostructure have been suggested [2~4] . The recommen ded triieoamylphosphate, diiaobutylisooctylphosphate and others,were suceeaful- ly tested for high burn-up fuel (100 GW day/t) short-term cooled (the solut ion activity up to 10' Ci/l [5])* The danger of the extractant degradation has been overcome through the use of centrifugal extractors having short phase contact time (extraction of 2 a, see [5] and the paper of A.S.Hikiforov, B.S.Zakharkin and others at this oonferenoe).Alternative ways of improvements suggested by the Prenoh and Italian researchers are also under study; I.e., the use of diluents- Isoparsffine. amides of oarboxylic acids instead of TBP. For the sake of the process optimization redox reactions of Pu.Hp.ind others are under systematic atudy (tie work by Koltunov V.S., e.g., [6] ). At the Radium Institute together with the scientists from the SSSR a process was develop ed to extract and successively isolate Important fission products - caesium, strontium, lanthanides-and TPE with chlorinated cobalt dicarbolyde [l] • High extraction, i.e., effective removal of TPE from raffiliates ie attain ed with powerful bidentate organophoephorus extraotants. At the AUSRITm such oxtractant* have been developed, e.g., tetratolylmetiurlenediphosphine dioxide
6 tol2P(0)0H2(0)Ptol2 (most powerful extractant H ) and ditolyldibutylcarba-
moylphosphine oxide tol2P(0)CH,(O)CNbu2; the effectiveness of both the compo unds is significantly increased due to the anomalous axyl strengthening effect revealed in 1975 'see [9i10J and the paper by Rozeii A.M. and coworkers at this conference). The extractants were also tested in reprooessing fuel irra diated to 100 aw dey/t [5]. At the Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR (GEOChI) B.F.Myasoedov and coworkers investigated many carbomoylphosphine oxides and diphosphine dioxi des including those with a rigid bridge that have a higher selectivity for the Fu/Am.U/Am pairs [11] . In the USA to extract TPE the TRUEX process is sug gested based on the use of octylphenyldilsobutyloarbamoylphosphine oxide
ootPhP(0)OHg(0)CNibu2 solubilized with IBP (see [12] as well as the paper of W. Shultz at this conference}. Due to the high extraction ability of diphos phine dioxides and carbamoylphosphine oxides there are difficulties caused by the need to suppress the extraction of fission products - zirconium, techne
tium and others-Howevervthese difficulties can be overcome, e.g., with complex- ones. Some powerful extractants have been suggested by B.N.Laskorin and D.l.Skorovarov and coworkers (Ail-Union Research Institute of Chemical Technology, see p j] as well as at the Aimim ДА,16] .
Actinide separation. Plutonium and uranium are rather easily separable from TPE. For the separation of the latter one can use the known TALSPEAK pro cess, extraction with D2JBHFA (e.g., ^S]1- It also seems promising to separate based on the ТРЁ conversion to different oxidation states. With this aim in the USSR systematic investigations of TPE redox reactions are under way. Fun damental results have been obtained at the Institute of Physical Chemistry of the Academy of Sciences of the USSR where N.N.Krot and others revealed heptava- lent ifp and other actinides (see [17J, reactions яге under study in complica ted complexing media (concentrated solutions of aoids and alkalies, extrac tants in organic diluents, solutions of isopoly- and heteropoly compounds etc); investigations are being carried on of the kinetics and mechanism of the indi cated reactions, influence of different factors on the reactions, including ultra-sound and presence of solid phase catalysts. The results of the investi gations are used to develop effective methods of transuranium element stabili zation in unusual or highly unstable oxidation states (amerioium (IV), curium (IV), heptavalent actinides} pY-19] as well as to develop new versions of ana lytical preparative or technological isolation and pirification of neptunium, americium and other actinides. Similar work is also being carried on in GEOChI where special attention was paid to the preparation and stabilization of TPE in unsual 3xidation states and their use in analytical praotice [20,21] e.g., separation of Am from Cm based on the conversion of Am(III) to Am(V) has been investigated. The extraction and separation of TPE from carbonate and alkaline media was also studied [22,23] . The equilibrium redox, extraction and electro lytic separation of TPE are under study at the Institute of Atomic Energy (V.H.Koeyakov, I.K.Shvetsov et al, e.g. [24] ). For TPE separation different versions of chromatography are successfully used (P.P.Nazarov and coworkers[2^).
It can be stated that effective extraction of aotinides from the wastes of extraction processes, TPE isolation and if needed, TPE separation are afforded by the existent methods (although there is much to be improved) • And until the
7
^ .-^чге. programmes of the complete usage of IPE emerge it is advisable to store them by the simpliest method. References 1. Taykanov V.A., Klimov A.V., Karelin Б.А. i dr.//Tret'ya Ysesoyuznaya konf. po khimii TPE.Tezisy dokladov. Dimitrowrad. 1986. s. 11. 2. Rozen A.M. ,Kikiforov A.S. i dr.// Avt.evid.SSSR 841140 s prioritetom ot 7.02.80. Byull.izobr. 1982. H 14. S.319. 3. Nikiforov A.S..Rosen А.И..Shmidt V.S,// XXI Jtendeleevsky e'ezd.Referaty dokladov. It. Nauka. 1981. 1.1. S.182. 4. Rozen «.JJ.,Hikiforov A.S. i dr.// Dokl. AH SSSR. 1984.T.274.S.1139. 5. Nikiforov A.S.,Zakharkin B.S.,Renard B.V.,Rozen A.M. et al/tsEC88sPapers. Moscow. 1988. Vol.IV. p.168. 6.Koltunov V.S.,Krot K.M.//Radiokhimiya. 1985.1.27.S.90. 7. Galkin B.Xa.,£atijnantovakii V.E.tLazarev L.N. et al.(USSR),Kadletaova L., Kyrsh M. ,Rais I. et al (USSR)// ISEC'88:Рарега.Мозсо»г. 19B8.Vol.IV.P.215. 8. Rozen A.M..Hikolotova z.I.,Kartasheva N.A.//Avt.evid.SSSR 601971. 1979- Byull.izobr. 1979. H 35. S.2571. 9. Rozen A.H.,Nikolotova Z.I..Kartaaheva N.A.//Dokl. AH SSSR.1975.T.222.S.I 51. 10. Rozen A.M.,Mikolotova Z.I.,Kartasheva U.A.//ISEC'8B:Papera.Moscow.1983. Vol.IV.P.133. 11. Myasoedov B.P.//ISE0'88:Papers.Hoscow.1988.Vol.IV. P.118. 12. Horwitz P.,Schulz W.// J.Leas Common Uetals.1986.Vol.122.P.125. 13. Laskorin B.H..Skorovarov D.I.,Filippov Б.А.,Yakahis V.V. 1 dr.//Hadiokhi- miya. 19S5. T.27.S.156jIS£C-88.Papers,Moaoow.1988. Vol.1. P.45. 14. Rozen A.M.,Volk V.I..Kartasheva N.A. .Mikolotova Z.I.//Radiokhimiya.1981. ^.23. Я.805. 15. Kovantsev V.N..Lebedev V.H.,Timofeev K.A..Buklanov G.V.// 3-ya vses.konf. po khimii TPE. Dimltrovgrad. 1988. 5.27. 16. Rozan A.M.,Mikiforov A.S. i dr.//Atomn.energ. 1985. T.59. S.413. 17. Krot N.N.,Gel'man A.D. i dr.// Semivalentnoe sostoyanie neptuniya.plutonlya, 1 americiya. M. sNauka. 1977. 18. Sinitsyn V.I.,Krot N.N.//Tzvastya AH SSSR. Ser.Khim.1982. Я 4. S.S21. 19. Krot N.N..Myaaoedov B.f .//Radiokhimlya.1985. 1.27. S.342. 20. Uyasoedov B.F..Lebedov I.«.//Radioohim.Acta. 1983. Vol.32. P.55. 21. Myasoedov B.P..Timofeev O.A.,Lebedev I.A.,Kulyako Yu.U.// 3-ya Vses.konf. po khimii TPE.Tezisy dokladov.Dimitrovgrad. 1988. S.5. 22. Karalova Z.K. I dr.//Radiokhimiya.1987.1.29.S.335.767. 1988.T.30.S.203. 23. Karalova 2.K. et al.//ISEC'88:Papers.Moacow. 19S8. Vol.IV.P. 150. 24. Kosyakov V.H. et al.//ISEC'88:Papera.Mosoow.1988.Vol.IV.S.15J. 25. Pireova T..A.,Chuveleva Eh.A..Kharltonov O.V.,Nazarov P.P.//Vses.konf. "Problemy proizvodatva 1 primaneniya lzotopov i istoohnikov yadernogo iz- lucheniya v narodnom khozyaiatve SSSR.Tezisy dokladov. TsBIIATOMHIFORM. M. 1988. S.49.
8 CHEMICAL PROPERTIES OP TRANSACTINIDE ELEMENTS PRODUCED BY HEAVY ION I 2 INDUCED REACTIONS: PROBLEMS AND EXPERIMENTAL Sl'UDIES ^ " I»Zvara- Joint Institute for Nuclear Research, Dubna, USSR
The halt-lives o£ the longest-lived isotopes of elements 104 (Xu) and Ю5
103i Ku, Hs, might not be the congeners of 5d-elementet Lu, H£, Та, (as one would expect from the regularities of the Mendeleev System) but that they might rather behave like homologues of the 6p-elements, Tl, Pb, Bi. Early experimental data on elements 103 to 105 did not Indicate any p-character in their compounds. In addition» recently at Dubna /67 there was compared the behaviour of atomic Eu and atoms of a number of known elements from various groups of the Periodic System at high temperature under reducing atmosphere* A conclusion was made that ъЬе sublimation enthalpy of metallic Eu must be at least twice as large as the value for Pb, and probably close to that for Hf. In overall agreement with thie, other authors FG showed by similar experiments that atoms of element ЮЗ behave like actinoida rather than like Tl. As any extreme RE do not seem to manifest themselves, most recent studi es have been designed to reveal and quantitatively measure more delicate differences in properties between element 103, Ku, Hs and their 5d-homologu- es. The thermochromatographic technique was used to compare the volatility of bromides and chlorides of Ku and Bf, Ns and Та /87. It was found that, generally, the compounds of Ku are absorbed on the column at lower tempera tures than are Hf species, i.e., the former are more volatile. Ehis was expected, indeed, from some simple considerations concerning RE. But the two elements differ also In the sense that the zone of Ku is broader than the 9 peak of НГ which, may indicate different reactivities fcf. The experimental methods developed for the comparative aqueous solution chemistry studies of Ku and Hf using ion exchange columns &J seem suitable to look for the oxidation states ox' Ku lower than 4-*-. Solution chemistry ox' elements 103 and 105 has recently been studied also by groups from the USA and PRG ZlO-127. To identify RE it is also desirable to develop further chemical theories and to perform relativistic calculations of atoms and moleoules as» in principle» certain differences in the properties of homologous elements may not necessarily originate from RE- Recently very detailed relativistic multi- configurational calculations of the Ku atom were done Z~147* It nas shown than due to both RE and multiconfigura* ional interaction the ground state of the atom is 6d7s p beeing 0.5 ©V lower in energy than the otherwise expected 6d27s - But the patterns of the atomic excitation states and the characteristics of orbitals in Ku are very close to those in Hf. This is why the strong p-character of bonding in Ku compounds cannot be expected. Onoe again it was confirmed that RE are to be sought for in the quantitative differenceв of properties of elements within subgroups of transition metals. Prospects for the future of the chemistry of the new elements crucially depend on the interaction of the developments in experimental approaches, in the theory and calculations. To study the chemical character of element 106 and perform its chemical identification by thermochromatography are practicable problems. There have already been attempts to chemically isolate element 108 isotopes as short-lived as 10 ma taking advantage of the unique properties of 0s tetroxide and assuming similar properties for the analogous compound of 10B /157* For still heavier elements with millisecond half-lives one needs novel experimental approaches/^e/. References 1. Oganeasian Yu.Ts.et al.//Wucl-Phys. 1975. V0I.A239. P.157. 2. Oganeasian Yu.Ts.et al.//Radiochim.Acta, iqa^. Vol.37- P.113. 3. Armbruster P. et al.//j.Lees-Common Met. 1986. Vol.122. P.581. 4. Oganessian Yu.Ts.et al. Preprint JIKH D7-87-392. Dubna, 1987* 5. Keller- O.L.//Radiochm»Acta. 1984. Vol.37. P.169. 6. Zhuikov B.L. et al. Preprint JINR R6-88>.109. Dubna, 1988. 7. Bichler B. et al.//Inorg.Chim.Acta. 1988. Vol.156. P.261. 8. Zvara I.//Int,School-Seminar on Heavy Ion Physics. Dubna, 1986- JINR D7-87-68. Dubna, 1987. P.145; Timokhin S.W. et al. ActinideB-89. 9. Saeglowaki et al.//Actinides-89. 10. Soherer et al.//Inorg. Chim.Acta. 1988. Vol.146. P.249- 11. Jest D.T. et al.//Ibid. P.255. 12. Bruchle V/. et al.//Inorg.Chim.Acta. 1988. Vol.146. P.267. 13. Gregorich K.B.et al.//Radiochiro,Acta. 1988. Vol.43. Р.22Э- 14. Glebov V.A. et al.Preprint JINR R6-aS-201. Dubna, 1988. 15. Zhuikov B.L. et al.//Heavy Ion Physics-85. Report JINR R7-86-32Z. Dubna,1968, P. 15. 26. 16. Plerov G.N.//Inter.School-3emlnnr on Heavy Ion Physics. Dubna, 1986. JINR D7-87-68. Dubno, 1987- P.9.
10 RBCEHT DEVBLOIMHtr IV RAPID RADlOVTiaUZKL SBPARATIOH Гу"Т G.Herrmanu. Institute of Kuolear Cherjiatry, ' Poatfaoh. 3980, D-6500 Mainz, PRG Gee jet systems loaded with aeroeola hare now becoae a stan- derd technique for the rapid transportation of reaction products from a target area to a set-up for chemical separations. The jet systems can be combined with various n«thc£s to perform rapid radiochemical separations either In a continuous or In a dlooon- tinuoas-cyolic mode of operation. Bzaaples to be dloousaed are: 1) collection, of volatile species at lur temperature; 2) thermo- chromatography of volatile epeolee at moderate temperatures; 3) solvent extraction from aqueous solutions by high-speed oent- rifuges; 4) automated procedures for solvent extraction and ion exohange chromatography; 5) feeding of the jet into the ion so urce of a mass separator*
CKHIXCAL THBHMODraAMICS OP THB ACTIHIDBS AHD THBIR Г COMPOUNDS: AH OVBRVIBW 07 RBCBHT ADVAHCBS L J.Puger. Commission of the Buropean Communities Joint Research Centre Institute for Transuranium Elements Fostfach 2340, D-750C Karlsruhe, 7RG After a description of the main area in which our knowledge of the chemical thermodynamic properties of the actinides and their compounds has progressed in the recent years and an examination of the status of the national and international efforts to assess the existing data, emphasis will be given on selected families of compounds, namely binary and complex halides and oxides, and organometallics.
The stability, versus a» nary species, of the complex oxides (and halides) of actinides (Ш to VI) with alkali metal and alkaline earth oxides (and halides) will be examined and compared to that of the corresponding tanthanide (Ш and IV) compounds. These thermodynamic parameters will be related to structural properties obtained from diffraction and spectroscopic (Ш, Raman) data.
Recent progress in our knowledge of the energetics of actinide (thorium and uranium) - ligand bond in organometallic compounds (mainly with cyclopentadicne and indene derivatives, and also with cyelooctatetraene) will be discussed and comparisons will be made with a number of analogous compounds with d transition metals.
Finally, an account will be given of the area in which experimental results are needed.
11 METALS Ш> INTEKMETALLIC COMPOUNDS. BbECTROMIC STRUCTURE AMD MAGNETIC PROPERTIES Ш Borje Johansson, Condensed Matter Theory Croup, Physios Department, Box 530, S-751 21 Uppsala, Sweden OUe Eriksson, Condensed Matter Theory Group, Physics Department, Box 530, S.751 21 Uppsala. Sweden H.S.S, Brooks, European Institute for Transuranium Elements, Postfaoh 2340, D-7500 Karlsruhe, ERG Our recent electronic struoture studies for a large number of acti niae An systems will be presented. The calculations have been done by means of the linear muffin tin orbital method (LMTO) together with the local spin density approximation and both soalar relatlviatlc and fully relativistic treatments have been performed. Besides the pure An metals, the AnKh, compounds are regarded as an excellent example of systems where the behaviour of the 5f electrons changes from itinerant to localized (rare-earth-like) as one prooeeds through the seriee. These properties are quite well reproduced la the calculations and the localization takes piaoe between PuRh, and AmRh,. The calculated equilibrium volumes agree well with experiments and it is found that the actlnlde(5f)-llgand(4d) hybridization la of the uttermost Importance for the Sf bandwidth.
Also the cubic Laves phase Anlr2 compounds show experimental features that can he associated with a '5f-ltinerant -w- 5f-looallzed' transfor mation as the nuclear charge inoreases. Again the calculations strong ly support the picture of a Mott localization of the 5f electrons as an explanation for the change of behaviour through the series. For a number of Aniig series of compounds the PuM^ system is anoma lous in the sense that HpM^ is magnetic while PuM^ shows a tempera ture independent paramagnetism. This is for example the case for PuSn„, Prom a relativistio formulation of the Stoner criterion for magnetism, it is calculated that PuSn, Is stable in the paramagnetic phase*
The f erromagnetism of the AnFe2 series Is particularly Interesting. Experimentally the Fe moment has been found to increase through the
series, for the eexiea UFe2, ЯрРе2 and PuFe2 also the actlnlde 5f moment is measured to inorease and Is parallel to the iron moment fox
lIpPe2 and PuPeg. Per UPeg the 5f moment is practically zero. All these features are anomalous in terms of spin only magnetism al though it is found that the Pe moment is relatively well reproduced by the oalcul&tione whert only the spin is allowed to polarize. However,
the calculated 5f spin moment is already substantial for UFe2 and In creases with the actlnlds atomio number. This increase seems in favour of the calculations were it not for the fact that the calculated 5f moment 1в entiparallel to the Pe moment, whloh is in complete dis agreement with the data. Inclusion of spin-orbit interaction gives rise to a relatively large orbital moment, induced by the polarizat
ion of the spin. Far U?e2 the orbital 5f moment is opposite to the 5f
12 spin moment and the two nearly canoel in agreement with neutron ex
periments. For NpPe2 and PuFe2 the spin Induced orbital moment is quite substantial but considerably laea than the spin moment, and the theory Is still in strong disagreement with data. Then the cal culation were extended to allow for orbital polarization (Bund's second rule) and a Stoner*lilce theory was developed with no free parameters. The self«consistent results then obtained gave 5f moments In good agreement with neutron experiments for UPe2, HpFeg
and fu?e2. Thus only after inclusion of all Hund's three rules Into the theoretioal treatment do the calculated 5f momentB agree with data* Also HpOSg and HpAlj have bees investigated theoretically. Again it Is neceaeary to include the orbital polarization in the calculat ions before agreement with experiment le obtained. UBoAl is calculated to Da paramagnetic. However, It is found that there is a small energy separation to a ferromagnetic state with a finite moment. This is the first theoretical calculation of a metamagnetlo behaviour in a 5f eleotron system.
(3 ELECTRONIC STRUCTURE INVESTIGATION OF ACTINIDES BY ГТ~\ PHOTOELECTRON SPECTROSCOPY LU
J. R. Naegele Commission of the European Communities Joint Research Centre Institute for Transuranium Elements Postfach 2340, D-7500 Karlsruhe Federal Republic of Germany
Photoelectron spectroscopy has become one of the most powerful spectroscopic tools to investigate the electronic structure of solids. A brief description of this technique is presented and includes angle resolved and resonant photoemission spectroscopy.
The specific problems encountered when applying this surface sensitive technique to highly a-active actinides are discussed, in particular a-protection and sample purity.
The aim of tbl> lecture is to demonstrate that photoelectron spectroscopy on the actinides offers a unique opportunity to study a transition from delocalized to localized electron behaviour occuring for the 5f electrons between a-Pu a ad Am. Therefore a review of existing photoemission data on actinides is given tor core levels as well as for valence states with emphasis on 5f electro:, properties. Recent theoretical calculations of the electron density of states (5f electron band scheme) and final state multiplets (5f electron localization) are discussed. The problem of separating these two contributions in the measured spectra is described. The importance of the Gunnarsson-Schonhammer theory and recent photoionization cross section calculations for the interpretation of photoelectron spectra of actinides is emphasized. Finally, the perspectives for future directions in electron spectroscopy of actinides are presented.
—ч_..;. __ THE BEHAVIOUR OF ACT:JIDES IH THE NUCLEAR FUEL CYCLE AND THE « . IMPLICATIONS FOR HASTE DISPOSAL | * | A Keylor and H Bccles- Technical Department, British R>?-?leax Fuel pic, springfields Works, Preston, Lancashire1, UK
INTRODUCTION The paper will describe the distribution of actinides and their daughter nuclides in the uranium fuel cycle processes, discuss their influence on waste disposal strategies and spsculate on future developments needed to reduce the impact of wastes.
THE ACTINIDES ДЫР TiffilR DISTRIBUTIOH IH THE HUCLEAR FUEL CYCLE The actinides and their daughter nuclides of significant importance in the uranium nuclear fuel cycle are thorium, uranium, neptunium, plutoniun, americiun and curium. In the separation and purification of uranium and/or plutonium they are discarded in wastes and effluents whilst contaminating plant and equipment. Their presence in wastes and effluents can influence the handling, treatment and disposal strategies, whilst plant and equipment may require decontamination prior to maintenance/routine inspection and for future decommissioning.
The natural decay of uranium-238 produces nuclides which present problems to both the mining/milling operators and uranium concentrate refiners. It is the heavy inert gas radon-222, the daughter nuclide of radium-226 which gives rise to the major concern during the mining operation, whilst the majority of radium-226 as well as thoriura-230 (parent of Ra-226) are discarded as tailings and after treatment are discharged to the tailings dam. In the separation/purification of uranium, the majority of the naturally occurring thorium isotope (Th-232), which can in some ores be three times the uranium concentration, is discarded in the liquid effluent which, after treatment is again disposed of to the tailings dam. However, it is the oxidation of pyrite (PeS2), a constituent of the tailings, by naturally occurring bacteria which produces an acidic sulphate solution which solubiliaes radium and thorium uuclidis. The latter can eventually migrate into natural water соигвев.
Although radon gas and radium tailings present the major waste management problems to the mining/milling operators, other wastes, some of which will be contaminated with actinides and daughter nuclides, are inevitably generated from the wet processes employed. Their impact on the environment however is comparatively small.
One of the main functions of the uranium ore concentrate operationr other thorium isotopes eg Th-234 and Th-230 will be present in the UOCs. The bulk of these isotopes are discarded in the TBP/OK purification circuit raffinate. A small proportion may precipitate as phosphate and/or fluoride in the UOC dissolution stage or in the solvent extraction circuit, particularly if these anions are present in the UOCs or are added to the process. Neutralisation of the raffinate followed by the collection of the precipitated nuclides and heavy metal hydroxides such as Fe(0H)3 minimises the environment impact of this liquid waste. Ho further separation of actinides occurs in the uoc refining and conversion processes until the intermediate uranium compound UF4 is converted to uranium nexafluoride UF6. In this conversion stage, the uranium daughters Th-234/Pa-234, which have re-established equilibrium with the parent nuclide, collect on the inert fluidised bed of CaF2 present in the UF6 reactor. As Th-234 and Pa-234 have comparatively short half lives, the treatment strategies of any wastes containing these nuclides ia simple; a delay storage of six months will allow thero to decay to insignificant values. The purification and conversion of UOCs to finished fuels, such ав AGR and FWR, uses both wet and dry process routes. These generate wastes o! a solid, liquid or gaseous nature in addition to uranic and non-radioactive residues. With the exception of the raffinate from the solvent extraction circuit, the actinide composition of the remaining wastes is negligible, whilst uranic residues are processed to recover their uranium value. 15 The spent nuclear fuel reprocessor is not only concerned with actinides such as uranium, neptunium, plutonium, americium and curium, but also fission products, eg ruthenium, zirconium, niobium and technetium. Although the wastes generated by tha reprocessing operations are more varied and greater in quantity than either the mining/milling of uranium ores or UOC refining, the distribution of nctinides is nevertheless confined to a relatively small number of waste streams. In the recovery and purification of uranium and plutonium from spent fuel the Purex-type solvent extraction process is used. Generally in the first cycle (highly active - HA) of this system, the majority of the Am, Сто and about half of the total amount of Hp with trace quantities of и and Pu are discarded in the high active waste liquor, along with the bulk of the fission products. It is the combination of short and long \ived radionuclides which can produce conflict Г^г the management of this waste. The separation in the HA cycle is achieved by judicious selection of process conditions, but the segregation is incomplete and further solvent-extraction cycles are required to purify independently the uranium and Plutonium liquors, in the uranium purification cycle (UP), the remaining trace quantities of fission products and plutonium, but particularly a significant proportion of the Np (about 40% of the original total) is separated from the uranium and is present in the UP aqueous raffiliate. The constituents oE the waste liquor which is discharged from the third cycle, the plutonium purification (PP) cycle are fission products, U, Pu and the remainder of the Np (~ 20% of the original total). The waste liquors from both purification cycles are.claesified as intermediate level wastes (ILWs). In addition to these other ILWs containing trace quantities of actinides arise-from - i. the shearing of cladding from the spent fuel; ii. clarification of the dlsaolver solution; iji. washing of Tributyl Phoaphate/Odourleee Kerosene solvent; iv. plutoniura fuel manufacture. Other wastes, particularly solids, are generated throughout the whole of reprocessing operations, some of them are contaminated with small quantities of actinides and are classified as low level wastes (ЫМ). Those contaminated with Pu are designated Plutonium Contaminated Materials and require treatment. FUTURE DEVELOPHEBTS The use of alternative leaching agents and/or a modified leach circuit could be advantageous for the future disposal of radium and thorium nuclides by the mine/mill operators. Although the wastes generated by the HOC refiners have a negligible impact on the environment, shorter routes may be considered for both economic and disposal authorisations particularly, if the latter become more stringent. In reprocessing technology consideration of the distribution and isolation of the actinides from the fission products need careful evaluation as the costs of waste management increase. Furthermore, there is a continuing need to assess the various alternatives of recovery, recycle and ultimate disposal of the actinides, with particular emphasis on plutonium and neptunium, and hence continued examination of separation process techniques including selective precipitation, ion exchange, filtration, extraction and alternative solvents to tributyl phosphate. 16 SYSTEMATIC PROPERTIES AND RECENT INVESTIGATIONS OF ACTINIDE METALS AND ALLOYS* H R. G. Ha ire and J. K. Gibson Transuranium Research Laboratory (Chemistry Division), Oak Ridge National Laboratory, P.O. Box 2CO9, Oak Ridge» TN 37830-6375 USA A wealth of scientific information has beun acquired on the actinides during the past two decades, due both to increased supplies of the heavier members of the series and the sophistication Of experimental techniques and instrumentation. Even with this influx of knowledge, experimental information becomes innreasingly limited when progressing to the members of the second half of the series, and it is normally not even feasible to perform classical solid state experiments with the last f ivs members (Es-Lr). For these heaviest actinides, it is at best only possible to obtain limited scientific data by special, novel or indirect approaches. This is indeed unfortunate as the trend toward divalency and other electronic effects (e.g., relativistic effects) that might be exhibited by several of these higher members are very interesting and important in understanding fully the complex nature of the actir.ide elements. since the chemistry and physical properties of an element are determined by its electronic structure and bonding, an important objective in understanding the aetinide metals and their alloys is defining or explaining the changing role of the 5f electrons in this series. Equally important is how various parameters, such as temperature, pressure, environments provided by alloys, etc., can affect or alter the unperturbed or "normal" behavior of the electrons of these metals., understanding the roles or mechanisms of such parameters allows their use as tools to probe the electronic structure of these elements, but such an understanding is also necessary for interpreting or extrapolating results from certain specialized experiments which are required for the scarce and/or highly radioactive materials. The solid state and thermodynamic properties of the actinide metals will be the main subject of this presentation. Ideally, such studies would be carried out using well-characterized samples of long-lived, high-purity metals. For several of the actinides this idealized situation has not or cannot be realized, one alternative approach for studying a scarce or highly radioactive material is to use dilute alloys of it in a host metal, studies of ouch aetinide alloys allow one to probe the metallic bonding of a selected actinide in different environments, and provides a convenient or unique means of studying 2.3ак.1507 17 it. Even when the quantity or specific activity of the material are not limiting factors, alloys can provide a means for stabilizing new phases/certain structural environments or inducing unusual electronic effects. In a related fashion, combining the actinidea with other metals led to the discovery of heavy fermions; also, alloys and compounds of the actinides with transition metals offer the potential for studying f-d hybridization. One important application of alloys in actinide research is the determination of cohesive energies via Kr.udcen effusion techniques. Although this technique has been used classically to study milligram to gram quantities of pure metals., by using alloys the technique can be used for determining the cohesive energy of even submicrogram quantities of an actinide. However, this approach demands an understanding of how alloying environments might affect the actinide's thermodynamics and bonding. The cohesive energy of a metal reflects the degree, of bonding present and from its magnitude one is able to assign ar metallic valence to the metal. For the actinide elements, such values sre useful for establishing trends, emphasizing differences, and inferring electronic structures for the elements. In the discussion presented here the emphasis will be on comparing the most recent information for selected actinides with previously reported results for the 4f and 5f elements, and on summarizing our present understanding o£ these elements. «Research sponsored by the Division of Chemical Sciences, Office of Basic Energy Sciences, United States Department of Energy under contract DE-ACO5-84ER2H00 with Martin Marietta Energy Systems, Inc. LARGE SCALE PRODUCTION AND APPLICATION SYNTHESIS OF SUPERHEAVY ELEMENTS IN REACTIONS WITH HEAVY IONS MPH0CB3SIHG 0» HIGH ВШШ-UP (100 GWd/t) SHOBT COOLED FUEL 1.1 A.S.Hikiforov, B.S.Zakharkln, Eh.V.Renard, A.M.Rozen, Eh.Xa.Smetanln. All-UnioQ Research Institute of Inorganic Materials, Moscow, USSR II 20*-Pu 80$ fuel of fast reactor (BR-10 and BOR-60) oorea and axial blan kets was subjeoted to reprocessing) the fuel was burned up to 10$ (100 CWd/t) and oooled from 3 months to 2 years. lha solution activity WHS up to 103 Ci/1. Ihe major difficulty, viz., a danger of an extraotaat damage, was prevented through the use of oentrlfueal extractors (CB) with abort phase contact time (2-3 a for extraction and scrubbing, 5-6 s for Pu product scrubbing froa V and V stripping, 10 a for carbonate regeneration}. The phase separation time was 20+5 a. Pilot contactors CB-33 were used; the smallest ones of the stan dardized aeries developed for radloohemiatry having throughputs from 25 1/h to 20 m3/h [1]. The second difficulty, vis., the possible second organio phase formation at a high plutonlum concentration waa prevented through the use of trlalkylphosphates with the optimized hydrocarbon chain, triisoamyl phosphate (TIAP), diisobutylisoootyl phosphate (SIBIOP) and others instead of IBP [2-4]. It was found that the Pu capacity of a 36* MAP -dodeoane solution was ~ 120g/l; during 80 day cooling no second organic phase formed.D1B10P has the advantage that the second organio phase does not form during thorium extraction either EH- Degl&ildlng. Along with the traditional method o. chapping the use was made of thermal methods that permit the deoladtting of fuel oooled for any period of time. Ihe melting of stainless steel structural materials at 1450-1550"0 in an Inert atmosphere allowed adequate ргооеев parameters to be reached: the amount of steel captured by fuel did not exceed Jf>, Pu losses with separated steel were up to 0.01S6, those with ceramic lining were 0.02*. the total yield of fuel components was 99.9% [5]. Dissolution was aooomplished with the traditional method (8-9 mole/1 НПО, at 100+500 for 6 hours), the final solution (prior to mixing with washing wa ter) contained ~ 250 g/1 (U*Pu). To fully dissolve hardly soluble residues, containing Pu, F was added. Clarification of solutions was accomplished in two stages: the coarse one (to a solid oontent of 30-100 mg/1) in a oentrifuge (it was early shown that to separate suspended partiolee 1-3 mem dia it is adequate to have a separat ion faotor of the order of Vr [6]), the fine one (to ~5 mg/1) using filtrat ion through metal powders* Ihe filtration rate (at the layer height of 400 mm, *p~300 mm W.O.) was 1.3 and 2.2 a/b for stainless steel powders of 0.2- 0.4 mm and 0.4-0.6 mm fraotiona, respectively» Ihe solution was clarified in a three layer filter 32 mm dla with the total layer height of 600 mm. Essen tially oomplete clarification was attained at the throughput of 1.5 m /m h (1.2 1/h) [5]. KWt""ltitlm operations Ы. Ihe first cycle was tested in a 43 stage cascade of CB-33. The flowsheet provided ten stages for и and Pu co-extraotion, two- cone sorubblng - 10 mole/1 KbUj (11-13) and 0.5 mole/1 HSOj (stages 14-16), reductive stripping of U/Pu using U(IV) (17-32). U stripping (33-40) and the carbonate extraotant washing (41-43). In a typical series of experiments the 20 initial solution (0.97 1/h) contained 165 g/1 », 23 g/1 Pu, 4.3 mole/1 HHOjj the extraotant (2 1/h) иао 30J5 IBP or 30* MAP or 40% DIBIOP. After scrubbing extraotant load «as 82+5 g/1 (U+Pu). The solution exchange number was about 100. She following results were obtained. With TBP, TIAP ana others the direct extraction of U and Pu was 99.99% that of Np was 98$ (to extract Яр up to 10 g/1 ammonium vanadate that oxidized Np to Np(VI) was added to a strong acid scrub solution, the factor of П decontamination from all M? was (1.5-1.6)10^ in case of TIAP and МНР (for IBP it is (1.2-1.5)x105)s that for Fu was 4x104, the factors of U oleaning from Pu were also 1.5x10 . Approximately the same deoontamination factors were reached in the control experiment in mixer-sett lers. It is important that despite a several tens of times reduction of the phase contact time in the reductive stripping unit (as compared to the mixer- eettler) with a simultaneous U(IV) consumption decrease from 1.4 to 1.0 kg/kg a high-quality purification of U from Pu resulted. An electrochemical U/Pu se paration version also worked successfully, for this purpose electrochemical cells generating 0(XV) were mounted on aqueous phase flow channels in the plu- toniuzn stripping zone of a separation unit. Ihe degree of the U/Pu separation was not worse than in the traditional version. Ihe operation of the 2nd ex- 2 traction oycle was also tested; additional decontamination of U from PP~-10 was reaohed. Finally, experiments were performed on transplutonium elements (and lantha- nides) removal from the first cycle raffinate using bidentate organophosphor us compounds (for their properties see f7,S] as well as the paper by Rozen АЛ. and ooworicers at this conference). When tetratolylmethelyaediphoaphine dioxide (0.5 mole/1 in trlehlorobenzene) was used, essentially full extraction with a 5 times concentration was accomplished in one stage; on extraction with di- tolyldibutyloarbamoylphosphine oxide 5-6 stages were required [5 , 9j. Ihus, it can be stated that the use of centrifugal contactors and trlalkyl phosphates with the optimized hydrocarbon chain inhibits extraotant degradat ion and the second organic phase formation, successfully solves the task of quantitative extraction, deoontamination and mutual separation of actinides on reprocessing fast reactor fuel of high burn-up and short cooling. References 1. Kuznetsov G.I. .Puahkov A.A.,Belyakov S.lt.//Atomnaya energiya.1986.I.61.S.23. 2. Rozen A.M. ,Jtikiforov A.S. 1 dr.//A.S.841140sprioritetom ot 20.01.60. Byull. lzoor. 1982. H 14. S.319. 3. Rozen A.H.lHiklforov A.S. 1 dr.//Dokl.AH SSSR.1985-I.274.S.1139. 4. Rozen А.И. ,Hiklforov A.S. 1 dr.//Atomnaya enarglya. 1985.T.59.3.413. 5. Hiklforov A.S.,Zakharkin B.S.,Renard E.V.et al//ISEC'8B: Paper. Moscow. 1988. Vol.IV.P. 168. 6. Rozen A.M. .Levishev A.H.,Hudel' A.H. i dr.//Atomnaya energia, 1976.1.40.3.46Ti 7. Sozen A.M.,Hlkolotova Z.I.,Kartaaheva N.A.//RadIokhim±ya.1986.l.28.S.407. 8. Rozen A.H..Mikolotova ii.I.,Kartasheva H.A.//ISEC'88:Paper.Moocow,l988. Vol.IV.P.133- 9. Rozen A.M. .Nikolotova Z.I.,Kartasheva K.A.//A3'SSSR. 601971. 1979. Byull. izobr. 1979. H 35. Я.2571. 21 STRATEGY WITH SPENT ШШ11Ш RECYCLIHG 1-2 E.A.Pilippov, I.B.Braverman, A.F.Tsarenko. All-Union Research Institute of Chemical Technology, Moscow, USSR Large-scale development of nuclear power in the USSR has been always inseparable from creation of an industri al infrastructure using a closed fuel cycle, commissioning of BN-type fast reactors and gradual transition to a self- sufficient power production regime. Still, the reality of energy development has required some revision of the pre sent conceptions for the closed fuel oycle with the stress on utilizing spent uranium and plutonium in thermal reac tors. The paper considers some economic criteria concerning the viability of transition to the closed uranium fuel cy cle, investigates the changes in the ieotopic spent urani um composition as well as influence of ' U and iso tope on the fuel recycling technology in principle. Some valiants of the fuel recycling systems have been discussed.. 22 SOLVENT EXTRACTION CHEMISTRY APPLIED TO THE THORIUM I \~$ FUEL CYCL6 L I Erich R. Msrz. institute of Chemical Technology, Nuclear Research Centre, D-5170 Jiilich, PRG Thorium nitrate can ae extracted from aqueous solutions into solutions of tri-n-butylphosphate (T8P) in hydrocarbons, This fact is utilized in the reprocessing of thorium based nuclear fuel £%]. Thus, the THOREX process has been developed to separate thorium and uranium from fission products, since these t..'o elements form easily extractable complexes with TBP in a nitrate system. However, the THOREX process is technically less advanced than the well-known PUREX process. It is principally incriminated with the drawback that thorium nitrate exhibits a lower distribution coefficient than uranium and plutonium. To drive thorium into the organic TBP phase, a strong salting out agent is required. Aluminium nitrate, which formerly has been recommended is now successfully replaced by nitric acid in order to reduce the amount of radioactive waste. However, high acid concentrations ere counter-productive in achieving high fission product decontamination. Therefore, several flowsheet variants with acid and acid deficient feed solutions, respectively, have been investigated in the past. In order to achieve high decontamination factors, a dual cycle THOREX process was developed [2]. This process usee an acid feed solution in the first cycle and an acid deficient one in the second cycle. Although distribution date for ThfND»). are available for the HN03/TBP system £jj, almost no information has been .available about the thorium species present in the nitrate medium and the extractable species. It could be shown that the system Th(N0-)4:HN03/30 % TBP in dodecane, the extractable species is the non-hydrolyzed Th ion, as determined by comparison of the distribution coefficient for the total thorium with the fraction of non-hydrolyzed Th + present at different pH values /47- These results were supported by distribution experiments using HNO~ and LiNO, as salting-out agents. The resulting distribution data make it possible to evaluate the hydrolysis constant of the first hydrolysis product of Th{IV), viz. Th(OH)3*. According to more recent investigations, a single cycle process with acid feed solution should provide the necessary decontamination factors [bj. The recommended flowsheet characteristics are depicted schematically in the following table. Included are approximate values for concentrations and flowfates. 23 Extraction Relative Flowrates feed: l.D M Th; 1.0 m HN03 1.0 Scrub: 0.1 H HMO, 1.0 Salting Acid: 13.0 И HNO, 0.2 Solvent: 30 X ГвР/Oodecane 9.0 Partitioning Feed: 0.15 M Th; 0.2 M HNOj 5.0 Strip: 0.35 H HN03 4.0 Scrub: 30 % TBP/Dodecane 1.0 U Strippinq Strip 0.0J И HNO- 0.Э An extra eo-extraction/decontaraination cycle proved to offer no decisive advantages. On the contrary, crud formation problems arising in co-stripping of thorium and uranium are difficult to overcome. Re-extraction should be carried out instead of Th/u partitioning at high acidity in order to prevent Th-TSP formation. For extraction, an acid feed solution should be used because otherwise precipitates might be formed during adjustment of acid deficiency. Pulse columns should be preferentially used es extraction apparatus, at le-ist for the first extraction cycle. They provide better overall performance then mixer settlers. Of utmost importance XE "heir contribution to overcome the serious problem of crud formation l]5j. Operational flow problems may be caused by the formation of stable emulsions, commonly called "crud", It could be shown that crud is generated by finely dispersed solids, originating from different origins like precipitates of zirconium with TPP degradation products, finely divided insolubles, or precipitates of thorium dibutylphosphste. All of them stabilize emulsions in an inmiscible organics/aijueous system. Reasons for their formation and in part of their avoidance are put forward. References 1.. A.T. Gresicy //Progr. in Nucl. Energy, Ser. Ill, Process Chemistry, Vol. 1 {1956)212-222 2. L. KOchler, L. Schafer, B. Wojtech//Kerntechnik V3 (1971)319-322 3. T. Nafcashima, E. Zimmer, E. Merz //Solvent extraction and Ion Exchange 2 (1984)635 4. T. Nakashima, E. Zimmer //Radiochim. Acta 3_7 (1984)165-16? 5. E. Merz, E. Zimmer//Report JUL-1899 (1984) ISSN 0366-0885 6. E. Zimmer. J. Borchardt//Nuclear Technology 75 (1986)332-337 24 AMERICIUM-241 PROCESS TECHNOLOGY I 1-4 James D. Navratll. The University of New South Wales.! — Kensington, Australia Americlum was first isolated in welghable amounts in the fall of 1945. Now a useful by-product'of the nuclear Industry, It is produced in Kilogram amounts by appropriate recovery, separation and purification processes. This paper briefly reviews Its production and separations chemistry. The isotope 2 Figure 1 shows a flow-sheet for the Rocky Flats process used to separate plutonium from 24iAm which is produced by the beta decay of s"Pu. Molten plutonium is contacted with a KCI-NaCl- MgCI2 salt mixture for one hour In a resistance-type furnace under an argon atmosphere at 750°C. Americium is oxidized by the MgCte to AmCI3 which reports to the salt phase. The salt Is separated from the purified plutonium metal and processed by aqueous methods to recover and purify the americium. Various processes, using ion exchange and precipitation techniques, have been employed to separate americium from plutonium and other elemental impurities in molten salt extraction (MSE) waste salts (Figure 2). The process Includes the following unit operations: (1) The residues are first dissolved in dilute hydrochloric acid. (2) Cation e.change or carbonate precipitation is used to convert from a chloride to a nitrate system and to remove gross amounts of monovalent impurities. Americium and plutonium form carbonate precipitates and can thus be separated from the soluble impurities. Likewise, the two elements can also be loaded on a cation exchange resin and eluted with 7M nitric acid. 03} The 7M nitric acid solution is then passed through an anion exchange column where only plutonium is loaded. (4) Americium in the 7M. nitric acid effluent is purified further by oxalate precipitation. (5) The amerioium oxalate precipitate is calcined at 600"C to yield Am02. 25 KCI 89 g MaCl 69 g MgCf, 97 g Impure Pu Metal Purified Pu Metal Stage 1 Stage 2 Ри 2000g Pu 1940 g 750°C 750° С Am 3fl Am 0-3 g PuOj Variable Spent Salt KCI 899 NaCI 69 g » To Aqueou» Processing MgC), 97 g Pu 6О9 Am 2.7 g Flow Sheet of Molten Salt Extraction Process Used to Separate Amerlclum-241 from Plutonium Q.5M HCI 7M NNO, O.SSM HNO, Oxalic Acid г PropotM 1 Cat banal e (- 00 1 -1 Prccipitati 1 1 A 1 1 ! ' ' " Diuaimian— Citron Anion Oaalatt CtlCinaiion Filtrinan E«change Еиспапде Precipitation IO AmOt | ' ' ' ' ' EKIuent Elualt FiCraie Fig. 2. Flow Sheet of Process Used to Purify Anericium References 1. Schulz, W. W. The Chemistry of Americium; ERDA Technical Information Center: Oak Ridge, TN, 1976. 2. Navratil, J. D.; Schulz, W. W„ Eds.; Transplutonium Elements • Production and Recovery, American Chemical Society: Washington, D.C., 1981. 3. Edelstein, N. M.; Navratil, J. D.; Schulz, W. W., Eds; Americium and Curium Chemistry and Technology, D. Reldel Pub. Co.: Dordrecht, Holland, 198S. ACTIMDE RECOVERY FROM RADIOACTIVE UQUH> WASTES PRODUCED BY ENEAj EXPERIMENTAL FABRICATION AND REPROCESSING PLANTS BY CMPO* M.CMercl,G.M.GaepBrtnl,e.GroMl Fuel Cycle Oepartment,CRE CasaccIa.ENEA.Rorne.ftaly * Most of the research activity reported here was carried out in Ihe frame of the European Community R and D Programme on Management and Disposal of Radioactive Wastes (Shared Cost Actions) Summary The use of a special mixed so!vent(iributylphosphain plus a carbamoyl-methylphosphinoxlde derivative, diluted In chlorinated or aliphatic hydrocarbons) in nuclear plants liquid waste decontamination, has been investigated. Experiments on separation of actinides from typical waste streams produced by ENEA experimental fabrication and reprocessing plants are reported. 1-lntroduetlon In order to remove all the actlnlde alpha activity From liquid wastes, it is necessary to find an extracting system capable of separating not only the tetravalent and hexavsient (essentially U, Pu, Np), but also the trivalent actinides (essentially the transplutonium elements). Actually, the main problem of TRU (transuranlc) waste processing involves the extraction of tr'walenl actinides (together with the tetra and hexavalent actinides), because of thq presence of significant concentrations of Am and Cm (III) in the liquid wastes. The blfuncllonal extractant octyl{pheriyl)N,N'diisobutylcamamoyl-methylphosphinoxide (CMPO) shows a very strong extracting power for actinides, independent of the valence state, over a wide ranoe of acidities (0.Б-6М) [ij. This extractant can be obtained at high purity, its solubility in hydrocarbon and in chtarinade type diluents is satisfactory, and it can be -really improved, if needed, by means of a suitable phase modifier such as tributylphosphaie(TBP). For these reasons, the CMPO compounds have been widely investigated with respect to their characteristics In Np, Pu and Am(IH) extraction, and proposed as the mcst promising candidates tor the TRUEX processfTransuranic extraction). 2-Object and application of the га&дегсп work The aim of this research is mainly to check the behaviour of CMPO in the separation and recovery of transuranium actinides from liquid wastes, arising from the ENEA experimental facilities for mixed oxide fuel fabrication facilities and for reprocessing of irradiated fuels. Presently, about ten cubic metres of liquid wastes coming from the mixed Pu-U oxide (MOX) fuel fabrication are stored at the CRE Casaccia experimental facilities. Moreover,100 cubic metres of liquid high level waste (HLW), arising from reprocessing of material testing reactor(MTR) fuels as well as 25 cubic metres arising from reprocessing of CANDU fuels ,are stored In the fecffiiieso f ЕШЕХ experimental pftot plant. Tests for TRU separation from these liquid wastes were carried out, using a CMPO extracting system, both from solutions simulating their composition and from real wastes. 27 The linai purpose of the present research is to study and develop In the laboratory and, subsequently, in pilot scale suitable separation processes. In order to verity: • The feasibility of a simultaneous separation of actlnldes (mainly U,Pu,Am),to decrease the alpha activity of the liquid waste down to a suitable level, in order to "declassify" the liquid waste from the third category"{HLW) to "second cateecry"(ILvV-U.W} according to Italian Nuclear Regulatory Body; - The possibility of selective separation of U, Pu and Am from liquid wastes of different compositions with a sfngte extraction procedure; - The possibility of recovering the actinldes In a suitable form to allow their reuse; - The extent of possible volume reduction of the TRU wastes minimizing the production of secondary wastes, Э-SfgnlHcant results obtained On the MOX Fabrication liquid wastes, batch and countercurreni extraction experiments have shown the possibility ol attaining a decontamination factor from actlnides and hence from alpha-activity of more than 103|2). A reference process was developed with separate recovery of Am and Pu. On the aluminium M.TJt. as well as CANOU high level wastes of EUREX «processing plant, tests were conducted with simulated solution. Also in this case a high decontamination factor from actinldes was demonstrated. Moreover, the same extractant and a similar procedure were successfully applied to sample of analytical wastes from control laboratories of the MOX fabrication plant. This result is particularly meaningful, as the absence In the waste solution of salting agents and the presence of many potentially compiexing species, stow the strong extractive power of CMPO in from of the actinldes. Reference [i1£P.TOHWrTZe!ai. TRUEX process for recovery of Plutonium and Amerteium from nitric acid waste solution-continuing development studies, Argcnne National Laboratoryreport 87/3(1987) I2JM.CASARCI, R.CHIARI2A. G-M.GASPARINI, GPUZZUOU and G.VALERIANI Separation and recovery of Transuranic elements from liquid wastes produced by the Casaccia Plutonium plant, Proceeding of ISEC 86. Moscow. URSS. July 18-24.19B8, vol.IV, 219; 28 TOTAL EXTRACTION OP TRANSPLUTONIUM АЛР RARE-EARTH ELEMENTS PROM WASTE SOLUTIONS OP "PUREX"-PROCESS BY PHOSPHONATE 1-6 G.V. Korpusov, S.I. TeaIon. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR Ae It la known, the task of extraction of transplutonium elements (TPE) from acid solutions of the fission products, obtained after reprocessing of the burned nuclear fuel, is caused mainly by two reasons: the obtaining of individual Am and Cm for tbeir further иве, and also by the necessity of se parate storage of radioactive wastes. Nowadays the later reason is the main one, as it is connect e« witi s the actual ecological problems* To perfora this process a lot of different methods are considered, howe ver, e preference is given to the elaboration of extraetionel scheme and it is much better/t7»B$8idea,much attention la given to the choioe of selective extrAotents, such as cbrbomoylmethylenphoaphonates and others {%). However, extractants considered are very often extracted together with TPE and the group of rare-eartb elementв (REE). At the eame time the task of total ext raction of TPE and REE can be solved using an available and cheap extractants from the class of neutral organophosphorous compounds (NOPC) /3 - 47* The values of the distribution ratioee of TPE ar.d REE for phosphates (e.g., tri- butnylphosphate) are low and little available for the process. Pbosphinoxi- des have the highest values of the distribution ratioee of TPE in the row of NPOC, they can not be practically used, as they have a number of dieadvanta- gps: considerably low concentration of HNO-, in the field of maximum of extrac tion; a difficulty of stripping, bad competability with diluent» and others. Phosphonatea are the best extractants for performance of multistage process of the total extraction of TPE and, REE ZT - 47* We have ohoeen a widely used diisookthylmethylphosphonate (DIOMP). Maximum cf the values of the distribution ratios of TPE and REE for DIOMP is in the mnge of concentrations of HNO. 1.5 - 2 HI, this is a little lower than acidity of waste solutions "PUREX" process ( Table ). This fact doев not prevent the extraction pro Distribution ratioes of Am, Cm and cess on the extraction cas Eu ve the HHO- concentration at their extrac cade, as phoephonates ext tion by DIOMP (100%) ract HM03 rather good, and its concentration on the HN03,M 0.3 0.5 1.0 2.0 3.0 4.0 corresponding stages can be decreased up to a de Am 0.30 1.62 1.90 2.08 1.64 1.18 manded value. The extrac Сш 0.28 1.50 1.S2 2.05 1.50 1.09 tion process can be suc cessfully performed as by Ей 0.32 1.8 2.B3 3.32 3.88 3.77 undiluted extractant so by its solutions in diluents in the limits up to 50% (V). Distribution ratio ee» e.g., of the Am decrease on maximum from 1.9 for 100% DIOMP up to 1.1 and 0.55 for 70% and 50%» respectively. The test was done on the model solution imitating evaporated rafUnate "PU REX" process to which isotope preparates of Аш-241, Сш-242, Би-152, 154; C«- 144 were *cded in the quantity of 10 mCu each, on the 30 staged mixer-settler extractv.r, including extractional scrubbing and stripping parts. DIOMP (100%} was used as solvent; water was used as strip and scrub solutions! The work regime was preliminary calculated, basing the value» obtained earlier, and then it wan made more accurate during tbe work. It was foreseen tbat acidity necaeeary for better total extraction of TPE and REE would be kept on a defini te number of extraction cascade stages. In the tested process a total extrac tion of HNO, into strip-product solution was foreseen for oetter extraction conditions of long lived isotopes of Sr and Ce from rafflnate. When the extractor attains tbe stationary regime we have determined the Am, Cm, Ku, Ce and HNO- concentrations in the coming out flows and in aqueous and organic phases on the extraction stages (Fig. ). As it is seen, to obtain sa SCRUB tisfactory parameters of the SOLVENT FEED SObUTIOK process, total quantity of ' stages of extractor can be decreased (8- for extracti 3i K pfc! I on, 2- for scrubbing and 4- for stripping). As a result 3 products Mere obtained: the concent rate of TPE and REE was mo re than 99.99$ at extraction; raffinate - weakly acid (ab out 0.12 И) solution of HKO- practically without TPE and REE, regenerated solvent, which could be put to the head of the process. The 15 10 15 strip-product solution was T>ro concentration change of Am and 95S. Eu in aqueous phase on the stages of the counter-current extractor in stationary regime References I*e separation and recycling of aotinides. A review of the state of the art / Ed. H.A.C.McKay. Directorate General "Research, Science and Education". Brussels, 1977. Hornitz E.P., Ifuscatello A.C., Kalina D.G. Separ.Sci.Technol- 19B1. Vol.16. P.417. ifikolotova Z.I., Kartashova Я.А. Extractia neytralnimi organicheeblmi BOedineniyaml. j|.: Atomlzdat, 1976. Korpusov G.V., Danilov И.А.,-Volodin I.A. et al^RadlokhimiyB. 1976. T.18. S.722. 30 THE STATE AND TENDENCY OP THE DEVELOPMENT OP PHYSIOAL-CHBMICAL Г ~—1 METHODS FOR GETTING MICROSPHERICAL PARTICLES OF ACTINIDES I I E.A.Pilippov, A.I.Karelin, O.P.Lobas, A.S.Papkov, A.N.Zhiganov, L.A.Mishina, V.I.ShaaUn. Polytecbnical Institute, Tomsk, USSR The atomic energetics development during the last years is characterized by a new glance at the tendency of a progressive increase of a total power of operating and being built powerblocks* Special attention In nuclear cycle development is given now to nuclear and ecological safety. Because of thie a new approach to being worked out techno logy of getting and «fabrication of nuclear fuel ia necessary. Improvement of radiation conditions because of minimizing the fraction or full exception of dust-forming operations at the stage of making tableted and vibro-packed fuel is possible to decide at the expense of using technology, which takes into account getting granulated actinide compounds. Sol-gel pro cess and the method of internal gelation, in particular, can decide a problem of getting nonduet-forming microapheric particles of actinide oxides» The ad vantage of this method is especially clearly seen, when getting secondary nuc lear fuel while making a closed fuel cycle. The method of internal gelation [ 1 J f based on actinide salts hydrolysis in a solution drop volume ac the ex pense of earlier introduced ammonia donors and next solidification of a drop, is the most perspective from the view-point of making a continuous distance - controlled process- Иге main way for improvement of this well-known method is to choose and investigate new kinds of inert dispersive medium with good aphe- те-forming properties, keeping a sphere drop of a dispersive working solution, containing individual actinides or their compounds in hetегоphase process of solidification. Most of technological schemes for getting microspherical par ticles with the method of "internal gelation" are based on beforehand drops formation with the help of different powder distributing devices placed above the columnB and reservoirs filled with liquid dispersive medium [2 ) . Being formed on the interface gas (air)-liquid, drops from a powder distributing de vice under the influence of gravitation get into a heated dispersive medium with the density lower than working solution density. A fallinp drop, keeping in thiB or that extent a spherical form, solidifies while passing through a dispersive medium and gets into the bottom part of the column. -Solidified gel- spheres are unloaded with the help of different devices and undergo the next treatment, including wasning from organic admixtures ( ammonia donors ), dry» ing and firing in oxide atmosphere till oxide forms of actinidee [3 ] . The main deterrent for wide usage of the similar schemes are principle drawbacks: initial working solutions, containing solidifying substances, have the tempe rature 70°-90° lower than the temperature of a dispersive medium, so powder distributing devices situated above the column with a dispersive medium are heated and blocked with spontaneous gelling initial working solution; being used rising circulation of a dispersive medium to increase the time, the mic rosphere being in the device, causes hanging up of fine microspheres in the device that causes often Btops of a technological process* These problems are settled when using heavy dispersive medium, the density of which is higher than that of a working eolution. In this case the process 31 may be made in a more simple device, providing introduction of a working so lution into гЬе bottom cooled part of the column with a heavy dispersive me dium and unloading of gel-spheres in the upper part (4 3 •Variations of diffe rences in densities of working solution and a diepersive medium are reached both by using new types of highdense inert liquids and reducing the working solution density because of reducing the metal concentration in it. As for using dispersive medium, liquid perfluoriiie-hydrocarbons are especially in teresting. A wide range in such parameters as viscosity, density, surface tension along with cheniica] inertia and absence of toxicity excites an interest to the given class of perfluorinehydrocarbon compounds. Tho combination of good sphere-forming properties, the possibility of physical-cneaiical parameters modification with the help of different surface-active sunstances on the ground of fluorine-organic compounds [5 ] » inertia and, at last, the high density of perfluorinehydrocarbon liquid, gives the possibility of princi pally кем process organization and gives a perspective of wide use of sol- gel process at the stage of the nuclear fuel refabrication in a closed fuel cycle. Though hetегоphase sol-gel processes of getting miегоspherical par ticles are multi-stage and connected with definite technological difficul ties» they are preferable in comparison with traditionally used powdered- compound of actinides from the ecological view-point. References 1. Forthmann R. Chemical Fundamentals of Hydrolysis Process for the 'Produc tion of Spherical Nuclear Fuel Particlee/KFA,JUL-950-RW,1973- 35 p. 2. Pilippov E«A. et al. The 5i;ate and Tendency of Physical-Chemical Methods Development for Getting Jfticrospherical Nuclear Fuel/Radiocnemistry. 1984. N2.P.225-239. 3. Haas Р.Л. et al.Chemical Flowsheet Conditions for Preparing Urania Sphe res by Internal Gelation//Ind.Eng.Chem.Prad.Res.Den,1980. Vol.19. P.459. 4. Filippov J5.A. et al. A Device for Getting Microspherical Particles/Chemi cal and Oil-Processing Muchine-Building.Express-information.Native Ex - perience. Series XM-I. 1984. И 14. P. 4-6. 5. Filippov Е.Л. et al. Investigation of Physical-Chemical Properties of a System: Dispersive Medium-Surface-Active-Substancee in Sol-Gel Process TI/1821, Research Inst, of Chem.Techn. USSR, Moscow. 1988. P.27. 32 UREA AMD UROTROPINE CONVERSIONS IN SOLUTIONS IN THE PROCESS OP Г~Г^—l MICROSPHERICAL NUCLEAR FUEL PREPARATION BY INTERNAL GELATION I I__J A.D.Karpyuk, N.S.Kolyada, A.I.Klyguin. All-union Research Institute of Inorganic Materials, Moscow, USSR Тле use of organic substances in the processes of microspherical nuclear fuel preparation £~1 J gives rise to a number of new non-traditional problems. These problems are above all caused by various conversions that organic com pounds introduced in the head of the process undergo. These conversions re sult in. formation of precipitates which retain and concentrate metal ions. Unpredictable gas release, formation of environmentally hazardous substances, etc are also possible. Urea and urotroplne conversion in solution was studied and the resultant compounds were identified in the paper on an example of the microsphere pre paration by internal gelation. Formaldehyde, methylol-urea and urea-formalde hyde resins were shown to be formed in the process. The techniques of urea and formaldehyde determination in solutions independent of the forms of their existence were developed. That made it possible to reveal the main trends in organic compound distribution in the process. The methylol-urea and urea- formaldehyde resin determination techniques [2J are based on the subsequent urea determination with p-dimethylaminobenzaldehyde. The standard deviation for the results is 0.02-0.04. The ammonia solution was established to contain approximately 90 per cent of organic compounds when the microspheres were washed. Up to 10 per cent of urotropine may accumulate in the dispersing liquid. The possible influence of the spent and newly formed organic compounds on the microsphere preparation process and waste reprocessing were considered. It was shown that urea-formalaehyde resin formation ia unlikely to have a decisive influence on the drop conversion into gel spheres. The rates of urotropine hydrolysis and methylol-urea and urea-formalde hyde resin formation were investigated as a function of the acidity of the medium. The change over from ammonia solutions to acids and the increase of the acidity of the medium favours the urea-formaldehyde resin formation and increases the fraction of water - insoluble polymers* References 1. Haas P.A.//Ind.Eng.Prod. Res.Dev. 1983- Vol.22, Щ. Р-4о7-4бб, 2, Karpyuh A.D., Kolyada N.S., Klygin A.I.Application number N 4099018. Favourable decision from 27.08.88. З.Зак. \ЬЛ 33 DISSOLUTION OP SPEHT PUB1 COHPOSITIOHS - INITIAL STAGE OP ~^~Z | AOMNIDB PRODUCTIOH BY OHSHICAL METHODS I Z 1 Sh.A.Nenarokomov, S.V.Pevtsov, V.I.Ionov. All-Union Research Institute of Inorganic Materials, Moscow, USSR Production scale is quite different for separate actinldes and is defined by their practical usage. Plutonlum-239 species widely used in nuclear power is produced in largest amounts* Neptuniuiui americium, ourlum and californium species are also produced. One of the sources of the above species is spent fuel of power reactors. The diversity of fuel rod compositions defines the approach specific for each fuel type» but the nitric acid dissolution of fuel is the main stage of aqueous extraction for all nuclear fuel types. From the standpoint of ohemical operations according to their composition the fuels can be arbitrarily divided into the following principal groups: uranium and plutonium oxide fuels - the major dissolution is conducted In 6-12 mole/1 НПО, for 2-4 hours followed by a full dissolution of hardly solub le residues (HSR) in nitric sold with the addition of 0.03-0.2 mole/1 fluo- rine-ior: metal base fuels - 10-12 mole/1 UNO. is used, the dissolution time is increased to 8-10 hours; uranium-aluminium alloys a::e dissolved using fluorine-ion and amalgamating hydrargirum additives; the dissolution of ura nium-molybdenum compositions is complicated by their low solubility (3-5 g/1) in a nitric acid medium of molybdate complexes; uranium oarbide and nitride fuels are oxidized with oxygen prior to dissolution; uranium -silicon alloys are dissolved in 10-12 mole/1 НПО, or subjected to preliminary oxidation which shortens the subsequent dissolution operation to 2 b-.ura. Investigat ions into the dissolution of the moat promising mixed oxide fuel showed that during 4-6 hours in 6-12 mole/1 НПО, in the temperature range 85°C-tb ^, the fuel composition which is a true solid solution is essentially fully dissolv ed. Depending on the fuel production conditions and its reactor operation the amount of HSR varies from 0*i to ЗЙ mas of the amount of the fuel dissolved; the plutonium content of HSR being proportional to the amount of the conhomo- genized portion of the fuel and equal to 2-6% mas. A fuller plutonium extract ion can be accomplished in a two stage process using 0.Q5-0..2 mole/1 fluorine ion additives in the second dissolution stage. Of interest in the valence of the main components In the dissolution pro cess. Uranium is likely to be U(VI). Plutonium is both PutIV) and Pu(VI). The Fu(VI)/Pu(IV) ratio in the solution depends on the dissolution conditions. It is established that the yield of Pu(VI) is minimum when the process is con ducted below the boiling temperature o£ the solution (80-90°C) at the Initial HMO, concentration of 12 mole/1 without air mixing; it is equal to 2-10% mas of the total Plutonium amount. 34 ACTIVITY OP tfASTE PROM WER-1000 SPENT FUEL REPROCBSSIHG L.V.Matveev, V.Y/u.Rogozhkin. Ali-Union Research Institute of Inorganic Materials, Moscow, USSR High specific activity effluents from spent nuclear fuel reprocessing ooo- tain more than 99*9 % of all the fission products, unextracted 0 and Fu tra ces and almost fully other transuranium elements - Яр, Am, Cm species £~1_7> The calculations carried out for a WER-1000 reactor show that the resultant effluents are by a factor of 2.105 more active than unirradiated fuel. The total activity is a sum of activities of fission products and actinides to gether with decay products. Their relative contribution varies during long- term storage* Initially the activity is due to fission products. However, during several hundreds of years (»»300 years ) the major portion of fission products decays and actinidea start to play the principal part. The problems related to actinides are more complicated due to their high radiotoxicity* The Table lists the results of calculations of the activity due to ectinides and decay products in WEH-1000 uranium fuel cycle waste. Attention is drawn by the high activity of Cm, Am and Pu for up to Ю4 уеагв and a considerable increase of Np activity during the following period of time through decay product accumulation» The calculations assumed the U and Pu content of waste to be 1 % of their totel amount in spent fuel. Actlnide Activity of Waste, fiq/t Time,уears Element Type 1 of 1 2 decay ю- 1 10 10 10> 10* 10» 10" U Л 8,0+8 8,0+8 8,0+8 8,0+8 8,1+8 1,0+9 2,4+9 1,4+9 P 9,7+9 2.4+8 2,4+8 2,4+8 2,4+8 3,8+8 1,4+9 8,8+8 Up d 1,4+10 1,4+1 ",4+10 1,4+10 1,4+10 1,5+10 3,9+10 7,2+10 £ 1,4+10 1,4+10 1,4+10 1,44-10 1,4+10 1,4+10 2,6+10 4,1+10 Pu zk 1,5+12 1,5+12 2,0+12 2,5+12 6,5+11 1,8+11 1,1+10 2,3+9 P> 5,0+13 4,7+13 3,1+13 4,0+11 2,7+8 4,5+8 1,5+9 1,2+9 Am o< 3,1+U 3,1+13 3,1+13 2,7+13 6,9+12 4,8+11 4,0+10 3,6+10 P 1,9+11 1,0+12 1,0+12 9,7+11 7.9+11 3,4+11 1,2+10 1,9+10 Cm 35 1 2 3 я 4 \Ч П1 ^\Ь ю 10" 10' 10J 103 lime, years Time dependence of MO„ cycle fieaioa product { 1 ) and actinide ( 2-4 ) activity of waete 2?3 2 - ( U-?u }02 cycle; 3 - K>aj 4 - < U-Th )02 References 1. Uikiforov A.S., Kilichenko V.V., Zhikharev H.I. Obezvrezhivanie zhidkikh radioaktivnykh otknodov. M.: Energoatomizdat, 1935. 2. Voznesensky V.A., Hikhamkin A.R., Sidorenko V.A., Skvortsov S.A.// Atomnaya energiya. 1977. Т.4Э. S.445. THE ШЫШГСЕ OF DAUGHTER RAffiEOHnCLIDBS OH PUREX PROCESS |— PARAMETERS l — B.Ya.Zilberman, V.M.Mosyazh, V.A.Starchenko. Kfalopin Radium Institute, Leningrad, USSR la extensive information en Purax process tor nuclear spent fuel regeneration, many data are presented on decontamination of uranium» Plutonium and, in some cases, neptunium from ^-emitting fission pro ducts (\J. At the same tine nuclear fuel delivered for reprocessing contains ^-emitting decay products of aetinides many of which have chemical properties closely approximating those of the end products; therefore the role of decay products may appear in final stages of the reprocessing process. Among these decay products are neptunium-239, uranium-237, protaetinium-233, thorium-228, thorlum-234 (with decay cbalnes) and others. The investigations on distribution of daughter radionuclides throughout the Furex flowsheet were conducted in the course of test reprocessing of (WER-440) fuel hatches with burn-up 30-32 GWt*d/t in shielded boxes. The flowsheet envisaged two uranium purification cycles, combined stripping of Pu and up by Pe (II) in the first cycle, Np extraction from reduced solution, oxidation and extraction concen tration of Pu from Np raffiliate. The analysis of daughter radionuclide distribution was performed by means of semiconductor ^epeotrometer connected with a minicomputer. The obtained results are given in Table 1. For comparison the data on distribution of the most extractable fission product (ruthenium-106) are cited there as well. prom Table 1 It is evident, that the fresh uranium strip solu tions from both cycles are free of neptunium-233, but contain a rather grest fraction of uranium-237. However, during the uranium-237 decay, thorium-234 accumulates. On further storage of regenerated uranium (see Table 2) the activity of decay products increases markedly. Other daughter radionuclides (239Rp, 233Sa, 228Th, 23*ИО are re moved from the first cycle with Pu and Up strip solution. In subse quent stages of reprocessing, Plutonium Is aocompanied only by pro- tsctiniuo-233. The storage of Plutonium produot (Table 2) leads to ac cumulation not only of americium-241, but also neptuuium-237, ura- nium-232, uranium-237, thorlum-228 and decay products of the latter. Prom the data obtained It follows that the storaged regenerated fuel may necessitate a repeated operation of reprocessing before re- fabrlcatlon. 37 Table 1. Distribution of Daughter Radionuclides in Purex-Proceas Specific activity of radionuclide, MBk/kg Product Ru-106 NP-239 U-237 Pa-233 Th-228 №-234 Feed solution 2.106 330 90 12 .8 12 Combined strip so 130 300 6 12 .a 12 lution of Su end Up of the first cycle Strip solution of 3t { .04 90 5 { .03 * .04 the first If cycle strip solution of .6 s .01 SO .5 4.03 i .04 the second и cycle Strip solution of Np .14 50 < .1 6 .7 10 Strip solution of Fu { •* { .5 50 5 .< .01 4 .1 Table 2. Accumulation of Daughter Radionuclides at the Storage of find Products Specific activity of radionuclide, MBk/lsg Radio nuclide IT storage, years Fu storage, years 0 .5 1 3 10 0 .5 1 3 10 Am-241 {.001 f.oo- {.001 «.001 {.001 <1 3.1-105 6.3Ю5 1.9Ю6 5.1Ю6 Hp-237 S.001 {.001 £.001 {.001 {.001 f .001 .03 .11 .93 9.2 U-237 Э0 4.001 f.001 $.001 f.001 <1 9800 9600 8700 6200 И-2Э2 .75 .75 .74 .73 .68 {.01 38 73 170 290 Th-234 .04 12 12 12 12 5.1 f .Л f-1 {.1 {•1 Th-228 {.03 .11 .21 .45 .64 {.01 3.8 12 76 260 Reference 1. Proc* Intern* Conf* on Nuel. Fuel Reprocessing and Waste Management "HBCOD 87*. Parle, Aug. 2>27» 1987. 3B DISSEMINATION OF INIS INFORMATION AND IAHA PUBLICATIONS f 1 IN THE USSR | ; V.S.Romanov, S.S.Rodin, I.A.MiKhailov.Atominfo:nn, Moscow, USSR IWis synopsis is presented. Atominform ie the National INIS centre in the USSR. Abstracting journals INIS-Atoraindex, issued in the form of printing editions and magnetic tapes, their cumulative indexes and microfiches of restricted distribution are INIS main output* INIS information covers world achievements related to nuclear science and technology,Including general physics, high-energy physios, neutron and nuc lear physics, chemistry, materials, earth sciences, isotope and radiation applications, nuclear engineering, nuclear reactors, instrumentation, waste treatment, different aspects of biophysics and radiology, public health, safety and environment, v-ray radiology and nuclear techniques In medicine, radiation protection, economy and sociology, nuclear law, nuclear documentat ion, safeguards and ispection, mathematical methods and computer codes, and other problems» Republican information centres under the Academies of Scien ces of all republics and departmental centres under the USSR Ministry of Power, Public Health, Geology and Agriculture are established to assist the NO in facilitating a more comprehensive input of information and wider in formation service of the users* Semimonthly abstracting issues and semi-annual cumulative Indexes of INIS Atomindex abstracting journal are the mair tool of information retrieval from the System* 3ach issue contains personal author index, corporate entry index, subject index, index of conference title (according to the date and place), index of report, standard and patent numbers. Atominform copies and distributes INIS Atomindex on magnetic tapes* Mag netic tapes automated retrieval allows to find precisely and quicfcly the required for the user information (in ihe 5-year retrospeotive mode) and promotes the reduction of INIS information array service time, as magnetic tapes are sent to the National INIS centres in advance as compared to a pub lished Issue. The report contains a rather detailed information related specially to actinides. The IAEA Is a large publisher. It publishes presentations on the above mentioned subjects in the form of: 1, Proceedings and resumes of conferences, workshops. 2. Technical reports* 3* Reference literature. 4* Periodicals. These publications are input into INIS and are disseminated by the Agency on subscription* Complete set of the publications are in the library of the USSR National centre - Atominform. Subscription conditions for information provision and оontract services are presented in the Atominform prospect. 39 PRODUCTION OF PLUTONIUM-237 D^Ll J. Aaltonen, R. Kattainen, and T. Aalto Department of Radiochmnistry, University of Helsinki, Finland K, Aho and J, Bergman The Accelerator Laboratory, Abo Akademi, Turku, Finland "vPu is a short-lived (T 1/2=45.3 d) isotope of plutonium. Because of the ease of the activity detection (X-rays 97.1 keV [12.1%|, 101.1 fceV (19.4%), etc.I 9J,TPu is a suitable tracer e.g. in metabolic and environmental studies of plutonium (1,2,3). 3>vPu can be produced e.g. with a cyclotron by irradiation of a"U with.a He-ions (4). In this work "'Pu was produced by irradating metal targets of 3 natural uranium with He-ions of 2BMeVr the maximum energy of the cyclotron of the Abo Akadexni Accelerator Laboratory. The thickness of the uranium targets were 0.175 mm. When the irradations of the uranium targets took place a vacuum foil of 0.025 mm stainless steel was placed in front of the targets. This foil reduced the energy of 3He-J.ons to 26 MeV, After the irradations the induced activity of *3VPu in the uranium targets were determined directly from the intensity of the К« X-ray peak of a:"Np at 101.1 KeV by x-ray spectrometry. The spectrometer consisted of a Ge(Li)-detector and a PC-multichannel analyzer. The activity of "vPu was also determined from the liquid samples obtained after the dissolution of the targets into nitric acid and after chemical separation of plutonium from uranium and fission products. The chemical separation of plutonium from uranium was made by anion exchange. The final purification of plutonium mainly from the fission products was carried out by solvent extraction with theonyltrifluoroacetane. The activity of И"Ри at BOB in the uranium targets irradiated from about two to five hours varied from about 7000 to 20000 Bq, respectively. After the chemical separation of plutonium from the irradiated targets the composition of "eFu and "°Pu in the plutonium fractions were determined by alpha spectrometry. The proportions of e the activity of « pu and «*pu in relation to the activity of 3avPu in the irradiated targets at EOB were about 1% and 0.1%, ^respectively. References 1. Todd* S. and Logan» H.//int.J.Appl.Hadiat.Isotopes, V7> *53 П9661. 2. Guary, I.-С., Hitjgo, I.i.w., Cherry, R.D. and Heyraus, м. it Mar.Ecol.Prog.Ser., A. 123 11981b 3. Gedeonov, A.D., Pelevia, L.A., Bakushlna, L.P. and Suprunenko, A.N. & Radiokhimiya, 29, 819 (19871. 4. Hat a, K., Baba, H. and Suzuki, T. //Appl-Radiat.Isot. .27, 713 (1976). 40 SEARCH FOR WAYS OP PRACTICAL USE OP ACTINIDBS AS ISOTOPE I ,_,4 ; ENERGY SOURCKS I I 1 N.A.Kalaahnilcov, B.S.Kallnichenko, I.K.Snvetsov. Kurchatov Institute of Atonic energy, Hoacow, USSR The paper is dedicated to the study of possibilities for practical use of transuranium radioactive isotopes. One of variants can be utilization of the mentioned isotopes in creating autonomous radiation-ohemieal installations for oxygen and hydrogen production. One of basic obstacles to the way of practical use of transuranium element (TUB) ionizing radiations is a low efficiency of radiation-chemical processes. It is known that the radiation-chemical yield of G(Hg) and G(02) depends on inherent characteristics of radiation and substanoe molecules, as well as on peculiarities of proceeding elementary reactions in the system, Initiated by ionizing radiation. In decomposing H20 and C0g affected by ionizing radiation specific plasma- chemical reactions [it2j oan proceed under certain conditions, which result in significant increase of radiation-chemical yields of molecular products. She possibility of proceeding the specific plasmaeheoleal processes was experimentally confirmed by the example of H20 and COg radlolysis by uranlum- 235 fission fragments [2,3] . The question on a concrete mechanism leading to the considerable growth of products radiation-ohemloal yield and the possibility of proceeding the mentioned processes under the action of various types of ionizing radiations leaves open. In the present paper the HjO (steam) and COg radlolysis by ^-particles was studied: The ct-partiole source (gold-curium-244 base alloy) had the power of 1.65.10 eV/в. Reaction vessel sizes and the source position were chosen so, that all «c-partiole energy would be absorbed in the (H^O, C02) reagent. The analysis of post-radiation products was run with the Ы01-8О chroma to- graph. Radiation-chemical yields of GG^) end G(C0) which dependences on the reagent density are given in Fig., were found through the known value of absorbed energy and the amount of radiolysle products. The dependences presented in Tig. were obtained for the first time. Bea ring in mind that a thorough study of the water steam and carbon dioxide al- pba-radlolyeia had not been performed so far and ranges of sharp increase in GCHj) and G(C02) are narrow enough! it is quite probable that given in Pig. anomalous values of radiolysis molecular product yields were not by other researchers. The question on the mechanism of initiation of the found апошаИев is interesting not only in itself but also in terms of general ru les of proceeding speolflc plasmaehemlcal processes in radiation-chemical eyetarns. Baaed on the character of obtained G dependences on the reagent density at Hurl ted quantity of possible ways for .use of radiation energy, which result in the increase of efficiency of molecular products formation (through elec tron exoltation» ionization» excitation of vibrational degree of freedom and dissociative sticking of eleoti-one) it was assumed that the most probable 41 reason responsible for the increase In radiolysis products yield can be the process of dissociative sticking (DS) of electrons to reagent molecules. To determine completely the mechanism of emergence of С increase effect under HgO end C02 irradiation by «(.-particles the complex physical and chemical investigation of studied radiation-chemical systems is required. n mol 12,0 90 S.O 4-a ' 20 40 «0 80 106 ISO №0 J>mg/cm3 Dependence of Ho and CO Radiation-Chemioal Yields on Reagent Density References 1. Beiousov I.G., Rusanov V.D., Pridmtm A.A.et al.The plasma radiolysis of water steams and carbon dioxide Ъу nuclear fission fragments//VANI. Ser. AVE. 1979. Vyp. 1(5). P. 43-51. 2. Khodulcv L.B..Griahin s.P..Kalinnlkov A.A.et al. Radiolysis of carbon dioxide Ъу U-235 fission fragments//KhVE, 1986,Vol.20, H 3. P. 230-236. 3. Kaiashnikov W.A,, Kalinnikov A.A. .Kraenoshtanov V.F. et al. Experimental studies of processes of radiolysis by fission fragments in water atean and carbon dioxide at high pressures/ЧАМТ, ser. AVE i T. 1985. Vyp. 1(20). p. 11-12. CHARACTERISTICS OP A HEUTROB SOOKSE i i BASED OH CmiDM-248 STOHTAHBOUS MSSIOH I *"15 I 5. U. Alexsndrov, 0. I. Batenkor, A. B. Blinov, U. V. Blinov, A. S. Krivokhatskii, 3. Я. Smirnev. Khlopln Radium Institute, Leningrad, tTSSB The properties of the г48Са nuclide are eptiaal for developing on ite base of long-lived standard neutron sources «1th a low gamma-ray background. The neutron yield of fluch a source equals 4.1.10* n/mge. the half-life of 2*8Cm, *>105 years, enables to use It for many years without decrease of the source's intensity and without calibration. Sources of "'СГ being in wide use at present, bare the half-life about two years. № energy spectra» of the source's neutrons and their yield don't depend on the properties of the median the 2*4Jm sample is in, neither they depend on the kind of the curium's chemical compound. The neutron yield from РАЙ the (at, a) reaction of such a source Is extremely small. "Cm nay be obtained within the scope of "wasteless* technology by using spent ' Cf sources applied in great numbers in different areas of national economy. The yield and neutron spectrum were measured of a ^Cm sample, on the basis of Intermetallie compound, which fully excludes the possibility of environmental contamination. The measurements' results shewed a possibility of broad use of 4 Cm for scientific and applied purposes as a standard neutron source. 4} STUM OF THE PAST CHEMICAL SEPARATICH OP DIVALEHT ACTIHIDES Г FROM NUCLEAR RBACTIOH PRODUCTS ' H.Xruehertselfer. Central Institute of Isotope end Radiation Research Leipzig, GDR The havlest aotlaldee (Z s- 100) «are produoed la very loir quantities in nuclear reactions at cyclotrons end at the present time we lmow only short lived isotopes* For the study of the ohenioal and phyaioal properties of these aetlnides and for the search for new isotopes, one seeds, first of all, fast methods for their separation fron the target or catcher materials and from the nuclear reaction products, produoed simultaneously. The exlatenoe of the stable speoles of divalent По and «И in aqueous so lutions allows one to use the difference between their complex formation constants and the distribution coefficients between two phases in ion ex change or extraction processes for their separation fron the other elements of this group. The search for the new ways of the fast -reparation of Ho and Hd at the first stage of experiments was oarrled out using the radioactive Isotopes of Sr, Bn and other lanthanldes. As a result of the investigation of the complex formation of lanthanldes and actinldea with some maoro'arelie ethers and their extraction Into the organic phase, new rapid separation methods were developed. The reduction of the trlvalent Гопа of the elements was per formed eleotrochemloally with an on-line speotrometrlc control or by amalgam of zinc [\J. The methods were used in nuolear chemical experiments at the heavy ion accelerators of the Laboratory of Nuclear Reactions in Dubne [2-HJ• To study the parameters of spontaneous fission, the nobelium frac tion produced by the reaction ™Cm(' 0, 3n) was purified by nobellum oryp- tate extraction Into chloroforms. The decontamination faotoLs from the trans fer products of Cm and the catcher material (Си, Al, An, .,.) and the percen tage extraction of Ho are very high, if the aqueous phase contains, besides the cryptand, also piarate and the pH value Is about 11 /i-3?- For the study of production In the 2«Cm • zalfe reaction fast me thods were developed for separating of Ku and Ho fraotions from other aetl- nides. The reaotlon products were eorbed at the top of a column filled with a strong acid cation exchange reels, then the Ku fraction was eluted by 0.511 KP solution, controlled with a radioactive isotope of hafnium, and subse quently the Ho fraotion, indicated by "sr, was washed out with a 1.5N HHO, solution A/. For Investigations of the chemloal behaviour of Hd the production of the pure Hd initial solution (with traoer quantities of Eu) by Isolating it from the produots of the reaction of 2<*'Bk with 2 Ne lone was carried out or. a chromatographic extrwtion ooluum (HD£B? eorbed on a supporting materiel). 1. Brucbertseifer Я., Kusaonnols M. et al. Zfl-Mltt. 99, 5. Leipzig, 1984. 2. Solcol B.A., Zelnalov Sh.S., Sharo Sh. et al. // JIUR Rapid Communicati ons, 19-86, 45. Cutma, 1986. 3. Huesonnoie Ж., Bruchertaelf er H., Constentlnescu O. et al. // IPN rapport annuel, 102. Orsay, 1987. 4. Bruchertseifer H., Husaonnols M., Constantlnescu 0., Bukianov C.V. // IPN rapport annuel, 103. Orsay, 1987. 44 RADIOCHEMICAL SEPARATION OP IBAHSPLUIONIUH BLEMEHTS in HEAVY IOHf . REACTIONS WITH ACIHTCDB TARGETS ! " B.Gorekl, Joint Tastltute for Huclear Research, Dubna, USSR In reoent years the nuclear reactions of heavy ions with heavy actinia's targets «ere extensively studied at JIUR, Dubna. These studies were carried out for the synthesis of new heavy elements and for the investigation of nuclear reaotlons. The transfermium isotopes synthesized by heavy ion reac tions can undergo electron capture, alpha-decay and spontaneous fission. The determination of the content of transplutonium elements (TPE) produced as transfer products as well as the products of alpha-decay of the compound nucleus is very important in the investigation of the interaction of heavy nuclei with heavy lone* Per the determination of the cross sections of nuclear reactions the yield of transplutonium elements oan be used. For this purpose the TPE must be separated from the target or from the catcher material and also from a great quantity of radioactive isotopes represent ing the elements from radium to plutonlum and fission products. The yields of these nuclides are quite low because of the small forma tion cross sections of the nuclear reactions. Therefore it is песеь~агу to perform separations relatively fast, with considerable yields and with high separation factors. It is known £5,27 that the cross sections for forming heavy compound nuclei drastically decrease with increasing atomic number while the cross sections for forming multinucleon transfer reactions and fission products are considerably higher /27 . Hence it follows that the degree of TPE purification must reach about 1010. In the studies of short-lived nuclei an on-line chemical procees is necessary with automated separation techniques /47 • She separation and determination of relatively long-lived actinldes is possible in an off-line process. In this paper we give a review of the frequently used separation methods. In recent time the main chemical separation prooesses are extrac tion chromatography with HDBHP, anion exchange and cation exchange with mixed media of mineral acids and organic solvents. We recommend for this purpose an extraction chromatographic method with trioctylphosphlne oxide (ТОГО) In combination with Ion exchange. ТОГО can be successfully used for the quantitative extraction of actinldes and lanthanides from concentrated salt solutions at low acid concentrations. A high selectivity of TPE and REE extraction towards fission products and other elements is reached when strong Gomplexing agents, such as diethylenetriaminepentaaoetate (DTPA) and lactic acid are added. Experiments were performed at the U-400 cyclotron at Dubna. Uranium targets were bombarded with * Аг 1опв at a beam dose of 10. The products from heavy ion reactions were collected using either copper or aluminium catcher foils. e In tracer studies ^^ 45 •5»,: ,",-'™«.. 4_ a high degree of TPE and REE purification from moat of the fission products, target and collector materials* The distribution coefficients in these systems for various elements era shown in Table. Extraction ol Various BXomenta by o.l If TOFO in Beoiene x's/on Solutions of Cu(N03)2, Cu Kd 0.5M Cu(M0 ) 0.5И Ou(N0 ) 7H HC1 Element 3 2 3 2 [H+J = о.эгн 0.07M DTPA IK laei. ac. [H*J - о.зм Ce 2.03 0.50 lb 4.56 0.67 io-3 Am 2.66 0.66 io-3 So 4.28 0.44 17-0 at 44-5 0.03 20.1 Zr 11.4 0.02 3-4 !№ 7.2 0.04 26.5 Bi 5.0 2-10"3 10 и 103 103 1С* Far the separation of ТРЕ and НЕЕ the cation exchange methods with Amlnex A5 and Option LGKS and А.-ШВ were compared. Individual fractions of TPB неге electroplated on Ft discs• which were counted for•£-activities. References 1. Oganeaairjx Yu.Ta.//Radlochim.Acta. 1984. Vol.37. P.113- 2. Oganessian Xu.Ts.//Proc.10 Years of Uranium Beam at the Unllac, Darmstadt GSI-86-19 (1986). 3. Oganessian Xu.Ts. et al. Preprint D7-87-392. Bubna, 1987. 4. Scbadel U et al. Preprint GSI-87-29. 254Bs: A GATBWAT 10 ТНБ HBAVIB3T ВЫИВНТЗ I 1-18 R.W.Lougheea. lawrenoe Ilvermore national lab., Llvermore, CA, USA '*Bs (Tt,j> 276 d) ie the heaviest target material available in suffici ent quantity for the production of even heavier, neutron rich nuclides. Bi- modal fission in the actiniae isotopes was discovered using reactions on this target. Six new nuclides, including two relatively long lived lawren- eium isotopes, have already been discovered using 5*Bs of only a few micrograms. Heavy Ion reactions on this small amount of material produce larger amo unts of the most neutron rich aotinldea than from any other target, yet it is possible to obtain ten times the ^*Bs presently available. We will Re view the disooverios made using this target material and dlacusa future di rections, including probing the stability of the 162 neutron subshell, sea rching for superheavy elements, and studytcg the chemical properties of meu- delevium, nobellum, lawrenolum using the long lived nuclides (i.e., 859 26a 21 (T1/2- 53 d), Bo (T1/2-58 m) and br (T.,/2- * •> Produoed from Bs-254 targets). Radiochemical Separation of Few Atoms ' 4.19 I of Trivalent Actinides in the Study of ! —I Isotopes with Z=104~UO M.Hussonnois1, H.Bruchertseifer2, fi.Gorski, O.Consiantinescu3, G.V.Buklanov, Yu.P.Kharitonov, A.V.Kykhlyuk, Yu.Ts.Oganessian. Joint Institute for Nuclear Research, 141980 Dubna, U.S.S.R. In the last years, the studies carried out at the JINR Laboratory of Nuclear Reactions have resulted in the synthesis of a number of new elements of the Periodic System. For the elements of Z up to 109, the main mechanism used for synthesis was the "cold fusion" of complex nuclei. In this type of reaction the magic 208Pb or 2°9Bi nucleus merges with accelerated neutron-rich tons heavier than Ar to form complex nuclei which deexcite by emission of one or two neutrons. More asymmetric target-projectile systems, like Ca+Th or Аг+U, were used to study the formation of a compound nucleus with Z=110. The identification of the sought nuclei is based on their two principal modes of decay. If the nuclei formed undergo spontaneous fission, they can be detected on line by fission fragments track detectors and their half-life can be determined from the track distribution. In the case of alpha decay, the sought nuclei can be identified off line by detecting a long lived daughter - 246£f for the doubly-odd nuclei 258105 , 262Ю7, 266109 and 253Es for the even-odd nuclei 257104, 261Ю6 and 265108. At the end of the irradiation, these radioisotopes can be radiochemical]у separated and identified by measurements of the energy and time spectrr. of their alpha decay. In the experiments aimed to synthesize element 110, the use of uranium targets instead of 208Pb leads to an increase of the yield of the transuranium nuclei formed in incomplete-fusion reactions, in particular of the fissioning isomers 240mfAm and 242mfAm> g0 in each experiment we measured the production of air* the elements ranging from Am to Fm. We will describe the radiochemical methods used throughout all these experiments to recover the divalent actinide elements. The purification of this fraction from the bulk target or collector material, from all elements from Ra to Pu and from many fission products is achieved by liquid-liquid extraction and ion-exchange chromatographic methods. The individual separation of the trivalent actinides is realized by elution from a cation exchange column with different concentrations of ammonium hydroxyisobutyrate. An ultimate purification of each actinide is ensured by HDEHP and anion exchange columns. This procedure allows us to obtain high decontamination factois (M08) from alpha emitters. We will detail the preparation of (he sources, suitable for alpha spectrometry, by electrodepositton on platinum disksor by electrospraying directly on the gold layer of the surface barrier detectors. The sample purity and the high detectin efficacity of the Si(Au) detectors, arranged in a geometry close to 4 7Г , permit high sensitivity in measurments of ultra weak alpha activities (at a level of I decay per month for E^ >6 MeV). 1 Institut de Physique Nucleaire, Orsay, France 2 Zentralinstitut fur Isotopen- und Strahlenforschung, Leipzig, DDR 3 Institute of Nuclear Physics and Engineering, Bucharest, Romania 47 THE VASSILISSA KINEMATIC SEPARATOR FOR THE SYNTHESIS AND STUDX Г ^ао'"" OP PROPERTIES OP THE NEUTRON-DEFICIENT ISOTOPfiS OP ACTINIDES AND I I_ , TRANSACTINIDES A.N.Andreyev, D.D.Bogdanov, A.V.Eryomin, A.P.Kabachenko, O.A.Orlova, G.M.Ter-Afcopian, Y.I.Cbepigin. Joint Institute for Nuclear Research, Dubna, USSR Recently in experiments using heavy ion beams the use of complete-fusion reactions has resulted in considerable progress in the synthesis and study of properties of nuclei fax from stability and in the production of a number of new neutron-deficient isotopes including some isotopes of actinide and traneaetinide elements* The experimental facilities used in those experiments had to satisfy the following requirements: rapid and efficient transport of nuolear reaction products from the target to the dotectorв, the high degree or suppression of background products and beam particles» Kinematic separators in which the spatial separation of the trajectories of the nuclides searched for and of background products occurs under the influence of tbe electric and magnetic fields find increasingly wide applications for such purposes. The VASSILISSA facility is shown schematically in Fig./V* *be separation of complete-fusion reaction products (recoil atoms) from "вР~рГ|УЛ.ЖЫ|М?fl I 'jpF^g the bean and multinucleon transfer and fission reaction products is performed by an achromatic system of three electrostatic dipoies w^th plane-parallel plates* The l~~J triplet of quadrupole lenses placed in front of this system collects recoil nuclei escaping from tbe target in the direction of the projectile beam within a solid ап-le of 10 er* The focussed compound nuolel pass through the aperture of the electrostatic dipolee almost without losses. The second triplet of quadru pole lenses, located behind the dipole system serves for focussing recoil atoms on the detection system* The detection system consistв of two (start and stop) time-of-flight detectors end a surface-barrier semiconductor detector wiliih recoil atoms get implanted to 127> The electronic detection system stores in computer memory data on the time-of-flight and energy of recoil atoms* and on the*X-dec&y and fission fragment energies, the time of arrival of signals from the detectorst time intervale between signals from compound nuclqi and signals from their iV- decay or spontaneous fission. This information makes it possible to find time correlations, and isolate nuclear decay chains, as well as to deter mine the half-lives of reaction products and to identify nuclides according to the genetic relationship in the ОС-decay chains. The use of kinematic separators requires the calculation and measurement of the efficiency of transporting recoil atoms from the target to the detectors. Complete-fusion reaction products are emitted in the direction of the ion beam with certain spread in angle , energy and charge state • To ensure a high efficiency of recoil atom separation the experimental facility should have a fairly large acceptance and transmit recoil atoms with, a large spread in energy ДЕ/Е end in charge state 4q/q* The acceptance angle in the VA5SILISSA facility is chosen to be equal to 10 sr. Calculations shown that some 50-80% of recoil atoms fall into this angle, depending on the projectile mass and the target thickness. The energy spread of recoil atoms is determined by the following factors: light particle evaporation from the excited compound nucleus, a difference between the recoil atom ranges in the target, fluctuations in ionization losses* According to calculations» the separator is capable of transmitting recoil atoms having the energy spread ДЕ/Е not exceeding 20%. The nuclear reaction products emitted by the target have very broad ion charge state distributions. Therefore a 20-30yug/cra carbon foil is placed behind the target. The use of a thicker carbon foil is inappropriate as increasing multiple scattering leads to a decrease in the fraction of the recoil atoms emitted within the acceptance angle . According to calcula tions, the separator is capable of transmitting recoil atoms with the ion charge spread дя/q not larger than 1055- The use of the stripper foil increas es the separation efficiency by a factor of 1.8-2.2, in agreement with the calculations. Experimentally the efficiency of separating (HX,xn) reaction products was determined by usi;,g He» P and Ar as projectiles C3* The results of the calculations and measurements of the separation efficiency are present ed in Table. The coefficients of suppression of beam particles were determined from the time-of-flight vs. energy two-dimensional spectra measured in the focal plane of the separator, which permit a rough mass identification of the nuclei reaohing the detector. The obtained values of suppression coefficients for low-energy particles similar to beam particles and having an energy B>1 MeV are listed in tab}a 1* The coefficient for suppression of particles with energies exceeding half of the primary beam energy was measured to lie la the Target Separation Coefficient Reaction thioloiess efficiency,$ of suppres oalc. ezv. sion 0.20 mg/om* 10*2 4*1 10^ "°Ег<Э1р,4п)Шв1 0.26 mg/cm2 16±2 14*2 1011 1И 40 1 Ву( Аг,4-5п) 99.200 10 ро 0*26 mg/cm 32*> 20*3 w Reference 1. Xeremin A.V. et al. JIUB £15-88-137. Dubna, 1988. 2. Andreyev A.N. et al. JIHR P13-87-914, Dubna, 1987- 3. Andreyev A.M. et.al. Rapid Oomm. JDJB N3(29)-88. Dubns, 1988. 4.3ак.1607 PRODUCTION OF Ac, Th AND U ISOTOPES BY 22Ne-INDUCED REACTIONS A.W.Andreyev, D.D.Bogdanov, A.V.Eryomin, A.P.Kabachenko, O.A.Orlova, G.M.Ter-Akopian, V.I.Chepigin. Joint Institute for Nuclear Research, Dubna, USSR She present-day interest in the values of cross sections for complete fusion in aeavy-ion reactions is explained by the desire to understand the nature of the limitations imposed on the process of fusion of two nuclei as well as by the fact that the problem of the magnitude of the cross section for forming complete-fusion products is crucial for designing experiments to study the properties of the isotopes of transuranium elements. In practice, model calculations are usually carried out to estimate the .cross section values. However, the degree to which the calculated results agree with experimental data is not high and can vary in a wide range, depending on the masses of the bombarding ion and the target nucleus. Dissatisfaction with this situation gives an impetus to the calculations and experimental work aimed at determining the cross sections for the formation of complete-fusion reaction products* Experiments were carried out using the U-400 cyclotron of the Laboratory of Nuclear Reactions, JINR. The projectile energy was varied over the range 100-130 MeV Ъу using aluminium absorbers. The separation of the complete- fusion reaction products from the beam and transfer reaction products was performed by the kinematic separator VASSILISSA Л »?7. The entrance slit provided the selection of reaction products emitted at angles smaller than -3° with respect to the beam* A detector system was placed in the focal plane of the separator and allowed one to obtain data on the energy and time of flight of recoil nuclei, on the time oi' their arrival in the detector* on the energy andtft-decay half-life of the nuclides "knocked into" the detector. The activity observed in the Ne + Au reaction is due mainly to the oL~ decay of Ac isotopes and their daughter products. The oontribution from the products of (oi,xnJ reactions does not exceed 10%. According to an estimate, 22 for the reactions induced by He ions the ratio of the separator efficienci es is ^-(xn)/^.(c^.xn) = 8-2* Hence it is possible to estimate the cross sections ratio for the 22Ne + Au reaction to be 64xn)/ ffM.xn^i.O. In the Pb + He system the cross sections of (*,xn) reactions turned out to be a factor of 30-60 larger than those of the reactions involving only neutron emission. The considerable difference between the ratios of cross sections, 6 fission one are close to each other [Г£&Г) one can express the ratio of the total probabilities of t<(<^,xn)(P* ,хпЛРлal) and (xnU?„(xn)(F„J) reactions in tba following form: p.j /p_\ Д /P'\ / r.\ Л /P-.\ £ /pn\ / Pf i so НегеГ£,Гп and I4 are the fission, neutron and «/-widths of the compound^ nucleus; i is the number of the stage of the evaporation cascade; Ijtf n are the corresponding widths for the excited nucleus with (Z-2, A-4) formed after the evaporation of one particle from the compound nucleus with the atomic number 2, The formula suggests that this ratio can to a considerable extent be determined by the ratio of fission widths Г^Г'^ of excited nuclei with atomic numbers Z and Z-2, and this specially applies to the region where the fissility parameter is strongly dependent on Z* As is seen from the exper imental data presented in the figure, the cross sections of the reactions involving the evaporation of 4-5 neutrons decrease by 3 orders of magnitude as one goes from Ac to U. Such a considerable drop of the (xn) reaction cross sections seems to be an adequate factor for a qualitative explanation of the relative yeilde observed in the (xn) and U,xn) reactions. We have also measured the decay properti es of the isotopes 225'2z6B. Their identifi cation was carried out by observing the genetically related ot-deoay events. Gross sections of the reactions involving the evaporation of 4-5 neutrons for the Z > 85 nuolei Present work Hef./У S (ms) S (keV) I. (ms) E (keV) I* 1/2 lu /2 20 225D 7870*20 100 30* 226„ ocn+150 7570*20 85*5 Z50-100 7430*20 100 500*200 7420*20 15*5 References 1. Yeremin A.V. et al. Preprint JIHR, E15-88-137- Dubna, 19S8. 2. Andreev A*tf« et al* JUffi Communications R13-87-914. Dubna, 1987* 3. Valli K., Hyde E.K. Borgreen J.//Phys.Rev. 01. 1970. P. 2115. 51 PRODUCTION AND SEPARATION OP RADIONUCLIDES 233'Pa , 23V 238Np, ! 1-22 239Np AND 240Am FOR SPECTROSCOPIC STUDIES E.S.Gureev, A.I.Muminov, S.Khujaev, Institute of Nuclear Physics of the Academy of Sciences of the Tashkent, USSR The main properties of exoited states of nuclei with atomic masses A > 200 are still not studies thoroughly* At the same time the effeeiency of spectroscopic studies of these nuclei to a considerable extent iepend on the purity of samples used which is due to the availability of reliable techni ques of separation for these nuclei providing the necessary degree of purity. Nuclear reactions used for production nuclei studied are -listed in the Table. Target nucleus Nuclear Intermediate Mode of decay Nuclide reaction product studied iiiii 233 233 п. У Th Pa 237 n, 2 n ц 238Np n, X 239^ f 239Np d, n 240Am As is know in isolating and puriflng of each radionuclide in group and lntergroup separating of aotinides and lanthanldes extraction and extrac tion chromatography methods are widely used. For extraction and purification of ^Pa from the thorium target irradiated with thermal neutrons extraction chromatographic eyetern HCl-TBP(F-4>-H2CgO. is found to be the most perspec tive. Halting use of 5% RpC2QA solution in 0.5 tool HG1 enables one to eluate protactinium from the column with narrow wash-out front. For convenience of performing spectroscopic studies the -"Pa nuclei were adsorbed on silicagel (100-200 mesh) from the 7*0 mol HWO- solution. Adsorption amount up to 99«5f> as a result of one fold phase contact. Radiochemical scheme of extraction and purification of 237U consists of two subsequent extraction and reextraction systems HN0v-TBP-Na2C03 and \l(N03)3-dlethyl ether-HgQ. The residual product is obtained as aqua solution of U(VI). For obtaining of the "8Np and 2^%p with high, radionuclide purity extraction-chromatographic system with stat ionary HDfflP on P-4 and mobile HNO- phases has been used. In this system Np(VX) transforms quantitatively into stationary phase. Eluation of Np from the column Is performed by transferring it into non-extractable pentavalent hydroxide from the nitric acid solution Is carried out. In so doing copre- clpitation of Up for more than 95% in one stage process is observed. Extrac tion of Pu(IV) in the system НЯ0--Н90о-Ш)ШР(с1есапе) Is used for Am ex- traction from the plutonium targets* Purification of ^Am from the accom panying fission products was performed using the HH4CNS(HC1)^HDEHP{S102) sys tem followed by extraction and reextraction of it in the HHgCNS(HCl)-D.AMP(de- oane)-HNO- system. Radiochemical purity of all radionuclides studied has been estimated by their 'jf- spectra, y— jf- angular correlation measurements have been carried out. Using Arna-Wiedenbeck's method of graphical analysis mult 1 pole mixing ratios have been determined for ^-transitions studied. The * Pu excited states populated in «"-decay of 238Np have been studied. Angular and pertur- bed angular correlations have been measured in the ^JNp and -^Pu nuclei. POSSIBILITIES OP 23fiPU AHD 237Pu PRODUCTIOH USING CHARGED | ,,33 \ PARTICLE ACCELERATORS l 1 7. a. Batil, V. Ya. Oolovnya, I. Yu. Gorshkov, Б. A. Gromova, V. D. Dmltriev, S. S. Kovaleako, O. I. Oaetrov, А. N. Smirnov, A. V. Stopanov, A. X, Prldkln, S. V. Khlehnikov. Khlopin Radium Institute, Leningrad, USSR The nuclear properties or * Pu and "*7Pu nuclei make then suitable to Ъе used as tracers for the analysis or plutonium content in environ mental samples and for radiobiological studies. The characteristics of following, nuolear reactions leading to z36Pu and 237Pu formation are analyzed! 238U(p,3n)236Bp—»236Puj 23 23 23 a3 3 237 ^НрСп.ап) ^- ^ С1,Щ "^(Зне.ап) ^; 5DC He,a) Pus 235U(«,2n)237PU; 238U(3He,4n)237Pu £3,4,57. The optimum irradiation conditions required for maximum radioisotopic purity and high yield of final product are determined* Special attention is paid to the possibilities of using for isotope production more available small-sijsed accelerators* neutron generators, small cyclotrons. Calculations and experimental studies of Pu production technique by "7Np(j-,n) 36Hp—»23 Pa reaction are presented. This method permits to minimize the impurities of 3 ' 39Pu, since their content in final product is completely determined by the degree of Яр purification from Pu with extraction chromatography. The advantage of this technique is also lower cost of electron accelerators compared to that of heavy particle accelerators» Experimental verification was performed by the irradiation of "'Hp targets with bremastranlung у-rays emitted under electron bombardment of «-targets. The electron energy varied in the range 10-17 He7. Extraction of Pu and its purification from V and Np impurities as well as fXom fission products was performed using ion exchange chromatography. The measured values of З'ир(у,п) reaction cross-sections gave the possibility to calculate the yield of Pu under different conditions of irradiations (electron energy, target thickness et al). It is concluded that experimentally achieved 3 Pu yield equal to —o —1 —i —i 5.10 * Bq pa a ' g ' can be substantially increased. References 1. Gromova E. A. et oW/Sov. J, At. Energy. 1983. Vol. 54. P. 116. 2. Kornilov H. 7. et al.//Sov. J. At. Energy. 1985. Vol. 56. P. 131. 3. Somura K. et al.//J. Duel. Sci. Technol. 19B0. Vol. 17. P. 647. 4. -Ahmad I. et al.//Phys. Rev. 1983. Vol. C27. P. 2239. 5. Gedeonov A. D. et al.//Proc. of 38 All-Union Oonf. on Hucl» Spectroscopy and Hucl. Structure. Baku, 1988. P.359. ОМСЕ ИОВЕ ОН MSB CHEMICAL EDEMTIFICATIOH AHD PROPERTIES I ,_г.~ OP KUECHATOVIUM . Yu.T.Chuburkov, I.Zvara. Joint Institute for Nuclear Research, Dubna, USSR Recently IUPAP and ЮТАО set up a working group to establish criteria for the recognition of the discovery of new elements, that then could serve to accord priority of discovery of every transfermium element* Having, this in mind and because of fundamental importance of the 1966-1969 Dubna 1*1-6/ chemicel work aimed at the determination of the place of elements 102 to 104 in tbe Periodic System, we felt it useful to briefly review here the logics of those studies as one still encounters Cll'an incorrect interpretation of oar experiments on tbe chemical identification of Ku. In the course of studi es of the chemical properties of tranaplutonium elements (IPE) Am to Em there was observed a smooth variation of many physico-chemical properties with in creasing Z. Hence to chemically identify element 101, Hd,it was sufficient to show that the stability of complexes of Md withA-HIBA fits into the series. To perform the chemical identification of element 104 the Dubna authors in vestigated the variation of the effective volatility (adsorbability) of chlorides in the series of elements with Z»94 to 104. For this purpose, the products of the nuclear interactions 2*2Pu+22He,180 and 2"Am+'1 0 „hich. contbined isotopes of elements from Pu to Ud with known properties, as well ав isotopes of elements Zsi02 to 104 which bad not yet been studied by that time, were continuously chlorinated by vapours of ZrCl., m>Cl5 and SQOl-.The mixture of chlorides was introduced into an isothermal (220-350°c, open chromatographic column and prooeesed in the regime of frontal gas-solid chro matography. She next part of the gas duct was a long flat (its cross section was 60x6 or 10 mm) flow-through chamber (200-2BO°C) where the chromatograpM.c retention o£ molecules could occur too. In the chamber mica fission track detectors were placed, the виг.(асе area of them being comparable to that of the column. Xh the above temperature range d- and p-elements passed quanti tatively through the column, e.g. there wee no retention of Sn at?200°C,the directly measured retention time of Bf was 0.5-1 a at 250°C and 0.2 s at 350°C. The table presents the conditions and results of experiments which differed in temperature, carrier-gas transit time in the column, t , and in t 1 S the chamber, t_, and other parameters. Column Fluence Transfer Number of temperature/°C of 2гНе/1018 *' <> of Am, % SF events 220-250 Л ,27 4.2 0.2 0.7-1.2 ~2 4 300-350 Л-57 1.0 0.2 0.7 -3 10 300-350 ДЛ7 3-2 0.1 1.5 -4 63 54 The transfer of НРБ chlorides through the column «as email, equal for elements Z s 103 within the experimental uncertainties and practically did not depend on temperature or other parameters. At the sane time the number of fission events detected by mioa per unit fluenoe in the reaction a*aPu+22No which was likely to produce г^',26010*,increased with temperature by at least one order of magnitude. This fact provides direct evidence for high volatili ty oi the chloride of the 3P nuclide obtained in the nuclear reaction. Ко less manifest evidence for this is presented in Fig. Here are compared the distributions (integral curves) along the mica detectors of atoms of ''^i>u, **3o, and of fission fragment tracks. Pu and So have the most volatile chlo rides of all the RBE. •/. .... —i—i— 100 50 Ku 20 t. 5c- Ю 1— - 5 Pu^fe~ •1 1 г [ • l 12345(7890' Detector number Obviously, the curve tor e S? nuclide with Z^.103 would be expected to have a smaller angle to the y-axis than that of Pu and So, i.e., it would be placed below them. It should be noted that in a number of control experiments £3,5,67 U> which '** 104 either could not be produced or the expected yield was veiy small, while the yields of various aotlnide isotopes increased /B/, the detectors registred only 4 fission events at a fluence of 4x10 particles. In addition,the U content of mica and the amount of plutoniun on detectors were carefully analysed. Measurements showed these possible sources of background to be negligible. All the above-mentioned observations provide sufficient evidence,that the SP nuclide yields muoh more volatile chloride than An,i.e. it cannot be an isotope of some element 22 22 with Z 55 outlined a scheme of the evaluation ox beat of adsorption,Q„, for chlorides of Hf, Ku and An to quantitatively characterize differences in the volatility of these species. In the calculations the apparent value of T,,£=0.5s was accepted and it wee assumed that all Ku atoms which passed the column decayed in the chamber, from this followed an upper limit for Q, of KuCl. on glass of 24 kcal/mol which is much less than 0. of An ohlorides. If,in this approach, the extreme present-day values of T^jfor '-""°"Ku are used (0.02B and 4.5s), the difference Q4 for the compounds of Ku and Hf turns out to be in the range from -2 to +4 kcal/mol, Q a. for HfCl. being 20 kcal/mol'3'. It can be seen that with the true f^j values the old upper limit for li„.of KuCl. does not need any reinterpret at ion. An accurate comparison of volatilities of Ku and Hf compounds by isothermal chromatography is difficult.iPhexmochromatographic method is much more suitable as evidenced by *he papers presented at this oonference. The most important conclusion made from the pioneering works' ' ' that Ku is an element of the V± subttroup in group IV» is not revised. References 1. Zvara I. et al.//At.Energ. 1966. Vol.21. P.83. 2. Chuburkov Yu.T. et al.//Radiokbimlya. 1967. Vol.9. P.637. 3. Zvara I. et al.//Ibid. 1969. Vol.11. P.163. 4. Chuburkov YAI.T. et al.//Ibid. 1969. Vol.11. P.394. 5. Chuburkov Yu.T. Prepr.JlHR. 12-4422. Dubna, 1969. 6. Zvara I. et al.//Radiokhimiya. 1970. Vol.12. P.565. 7. Hyde E.K. et al.//Hadiochim.Acta. 1937. Vol.42. P.57. 8. Plerov G.U. et al.//At.Energ. 1964. Vol.17. P.310. 56 I 1-25 H.Bruchertaelfer, O.V.Buklanov, H.P.Ivanov, O.Constantiaescu, Yu.A.Muzychka, Yu.Xs.Oganesaian, E.A.Sokol, G.M.Ier-Akopian, M.Hussonnols. Joint Institute for nuclear Research, Bubna, USSR The Interest in the properties of the kurohatovlum isotope 263Ku ie associated with the ejected relative stability of nuclei with a neutron number close to N»162 Zl-47 and with the discovery of the bimodal nuolear fission in the vicinity of Z.%100, В Ы58/У, which, if taken into account, can change considerably the spontaneous-fiBsion properties of this nuclide^ The present work was undertaken with the aim of producing by the reaction 248Cm (22Se,*On)263Ku. 248Cm was bombarded by 118 HeV 22He ions at the U-3O0 and U-400 cyclotrons of the Ш Laboratory of Nuclear Reactions. A total of nine 1.5-4 h bombardments were performed at a maximum beam intensity of 5n012 pps. The reaction products were collected by a gold catcher foil* After each bombardment the gold foil was solved in a mixture of hydrochloric and nitric acid, and the gold was removed by sorption on strong-base anion-exchange resin. The remaining solution was evaporated to dryness and the precipitate wae solved in a 0.51 solution of hydrofluoric acid and passed through a column filled with cation-exchange resin Aminex A3, The Ku fraction was obtained as an eluste and contained also the Mdioactive isotopes of the Hf tracer. All the actinides remained on the column. Divalent element 102 producible by 2"KU ot-decay, together with its tracer 'mSr, was selectively eluted by a 1.5H HNO» solution. For the preparation of sources for counting of spontaneous fission events the solutions containing the Ku end element 102 fractions were evaporated onto the supports and their spontaneous fission activity was measured using a system consisting of Si-Au detectors for fission fragments,BGO sointillatoia far prompt forays and Зне counters for neutrons (for Ku), and track fission fragment detectors (for element 102). The whole procedure of chemical processing and source prepara tion took 30-80 minutes. The measurements of Ku fractions were 5-8 hours in duration. In none of the experiments any spontaneous fission event has been recorded in the Ku fraction. Ho spontaneous fission has been detected in the element 102 fraction either. The results obtained allow one to estimate the JKu production cross section under various assumptions about the decay mode (spontaneous fission or d-decay) and the half-life of the nuclide (see Table). To interpret the result obtained we used known experimental data on the (HI,u3n) reactions involved in the systems 248Cm + 180 and 249Cf + 180, and on the (HI,4-5n) reactions in the systems z480m + 180, 243Am + 180, 2480m + l>, and 44Pu + "He. In addition, we carried out an experimental study of the (HI,3-on) and (HI 2 production cross section for 'Ku in the reaction 248Cm(22He,ol3n) 63Ku iB 57 The Limits of the 2 3Ku Production cross Section (nb), Obtained under the Assumption that the Nuclei Undergo spontaneous Fission (a) or ol-Decay (b)* with 100# probability Half-life, min 10 2.75 0.075 20 0.25 0.075 30 0.10 0.080 *Ы' Decay of 3Ku leads to the spontaneous fission of „_ following decay chain: 263Ku -^9i02 «g^ > 2594d Bfe1°g . calculated to be J cOn) Kuf obtained in our experiments, low enough, for making some conclu sions about the properties of - decay is not the predominant mode of •TGu decay, in contrast to other known odd-mass isotopes of Icurchatovium ( " 'KIX)M If this isotope decays mostly by spontaneous fission, then the half-life of 23Ku will be shorter than 20 min. The possibility of electron capture for this isotope requires a separate consideration to be given. References 1. Swiok S., Psshkevich V.V., Dudek J., Kazarewiea W.//Nuel.Phys. 1983. Vol.A410. P.254. 2. Leander G.A., Holler P., Nix J.R., Howard W.M.//Proc. of the 7th Int.Conf. on.atomic Masses and Fundamental Constants AMC0-7. Darm stadt, 1984./Ed.0.Klepper. Darmstadt, 1984. P.466. 3. Boning ;c., Patyk Z., Sobiezewaki A., 5wiok S.//' Z.Phye.A.1986 Vol. 325. P.479. 4. Lojewski Z., Baran A.//Ibid. 1983. Vol.329. P.161. 5. Hulet B.K. et al.//Phys.Hev.Lett. 1986. Vol.5fi. P.313- 6. Mo'ller P., Nix J.R., Swiatecki IV.J.//Los Alamos Preprint LA-UR-88- 2266, 1988. ELECTRONIC STRUCTURE AND SPECTROSCOPY CURRENT CHALLENGES IN THE USE OF OPTICAL SPECTRA TO TODEL ELECTROMIC [—"— STRUCTURE IN THE ACTINIDES* ' H. T. Carnall, C. L. Goodman and C. H. Williams Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois, 6ОД39, USA In this presentation we discuss primarily two issues, O) current attempts to reinterpret the spectra of trivalent actinide Ions, and (2) progress made in developing for the first time a .".ystematic interpretation of tetravalent actinide ion spectra over the whole of the series. In both cases the experimental investigations encompass both the absorption and fluorescence spectra of solid compounds. He assign the spectra in terms of energy levels of the appropriate Г* configuration using effective operators for electrostatic, spln-orblt and crystal field interactions. All these interactions are treated on ar. equal footing. When the full fN configuration must be truncated to a more reasonable size, free-ion eigenntates provide the basis for this truncation. A recent comprehensive survey of the speotra of trivalent Ianthanides doped into single crystal LaFa has revealed a number of new or previously poorly substantiated trends In interaction parameter values over the series. [1] Such an investigation provide» an excellent basis for the reexamination of trivalent actinide ion spectra ^o determine whether in fact similar trends exist, and whether* when recognized, they change any of the conclusions drawn from earlier wortt. The results of the reassessment will be dtscusaed. Our initial efforts to develop a systematic Interpretation of the spectra of actinide tetrafluorides over the whole actinide series have met with some apparent success in terms of establishing the magnitudes of the appropriate interaction parameters. However, recent crystal-field model calculations suggest modification of our phenomenoiogical approach. Hew spectroscopic results both rcr pure compounds and for actinides doped into CeFu and their role in & systematic interpretation will be sunmarizod. Reference 1. H. T. Carnall, 0. L. Goodman, K. Rajnak, and R, S« Rana, J. Chem. Phys. (in press). # "This work performed under the auspices of the Office of Basic Energy Sciences, Division of Chemical Sciences, U. 5. Department of Energy» under contract number w-31~109-ENG-38. 60 ACTIH1DES АНОНС ОНИ GROUPS OF ELUIEBTS OF THE D.I.MBMIIELEEV РШ10ШС SXSTBI H.B.lIlkheev, Institute of fbyaical Chemistry of the Academy of Soiences of the USSRf Moscow, USSR The paper considers the problems of the analogy between actinides and the elements of other groups of the D. I.Mendeleev periodio system- Actinides and transition elements have been shown to be analogous as regards the change of the stability of the higher and lower oxidation states with the growth of the atomic number of the element» The comparison of actinides arj lanthanides has shown, that the greatest similarity is observed between ti-o elements of the first half of lanthanldes and the second half of aotinldes. In their divalent state lantbanides and actinidee depending on their fd- exoitatlon energy can be characterised by the presence or absence of the electron in the ot-orbital, which accounts for the different chemloal pro perties of such elements an, fci' example, emerioium and ourium. Lantbanidee and aotinides with the ^d0 electron configuration have been shown to be the closest analogues of alkaline earth elements, and mendele- rium( 1) - the, analogue of alkaline metals. Tetravalent actinidea and lanthanides display marked analogy with tetra- valent d-elemests. With an increase in the oxidation degree the analogy bet ween actinidee and d-elemente becomes smaller, and the individual properties of f-elements more pronouced. Thus, actialdes represent a unique family of elements, which depending on their oxidation state, display analogy with practically all the groups of the D.I.Hendeleev Periodic System 0,H. References 1. Ulkheev N.B. // Radiokhimiya. 1988. T. 30, N 3. S. 297-313. 2. Hikheev И.В. // Ohemiker-Zeitung. 1981. Bd. 112, И 9. S. 255-263. 61 NEUTRON INELASTIC SCATTERING STUDIES OF ACTlWUJEl 2_o SYSTEMS I J G.H. Lander,1* W.G. Stirling,2 J. Rossat-Mignod,3 S. Kern,4 and C.K. Loong5 1. Commission of the European Communities, Joint Research Centre, Karlsruhe Establishment, European Institute for Transuranium Elements, Postfach 2340, D-7500 Karlsruhe, FRG 2. Department of Physics, University of Keele, Keele, Staff ST5-5BG, UK 3. Centre d'Etudes Nucleates, 85X, 38041 Grenoble, France 4. Department of Physics, Colorado State University, Fort Collins, Colorado 80623, USA 5. Intense Pulsed Neutron Source, Argonne National Laboratory, Argonne, Illinois 60439, USA The inelastic scattering of neutrons allows excitation processes in the energy range 1 to 500 meV to be probed on actinide materials. In this talk we shall concentrate on results obtained in the last 4 years and in particular those related to the magnetism of actinide systems. As we show, these experiments give unique and important information on the behaviour of the 5f electrons. In the first series of experiments single crystals have been used together with triple-axis spectrometers to examine magnetic dispersion relations. New experiments have been performed on USb [1] that show the inadequacy of a localised crystal-field model. Recognising the very large anisotropy present in ordered actinide systems, we have performed experiments at the Institut Laue- Langevin, Grenoble, on field-cooled single domain samples of PuSb [2] and UTe [3]. These experiments show for the first time that the magnetic response function is anisotropic, depending on the direction of the spin-wave propagation vector with respect to the easy axis of magnetisation. In addition to a sharp spin-wave spectrum, there exists in a system like UTe also a diffuse background of magnetic inelastic response. In this respect these ordered actinide compounds show similarities to the heavy-fermion systems. These experiments have been of central importance in developing the strong-hybrisation model of Cooper and collaborators [4,5]. In a second set of experiments we have exploited the potential of high-energy transfer scattering that is available with the new spallation neutron sources. Initial experiments at Argonne on UOz [в] were followed by higher resolution experiments at the Rutherford Laboratory (UK) source [7]. From these experiments on UO2 we now know the V4 and Vg crystal-field parameters. The 4th order parameter is over a factor of two smaller than the Rahman-Runciman 62 1966 [8] prediction, but equally interesting is the large quadrupolar interaction present [7]. These measurements have now been extended at Argonne to NpCb with rather puzzling results [9]. However, recently a sample of P11O2 has been shown to give two crystal-Geld peaks in the range 90 - 120 meV. This is quite unexpected because the ground state is a 14 singlet with matrix elements only to the Г4 triplet. A very large quadrupole interaction is needed to stimulate these results [10]. Both these series of neutron experiments point to inadequacies in our present theoretical treatment of these strongly correlated 5f systems. References [1] M.Hagenetal., Phys. Rev. B37,1846(1988) [2] G.H. Lander et al., Physica 136B 409 (1986) [3] G.H. Lander et al., Physica В (in press), Proc. of Int. Conf. on Neutron Scattering, Grenoble, July 1988 [i] G.J. Hu et al., Phys. Rev. B38,2639 (1988) [5] G.J. Hu et al., Physica. В (in press), Proc. of Int. Conf. on Neutron Scattering, Grenoble, July 1988 [6] S. Kern et al., Phys. Rev. B32 3051 (1985) [7] R. Osborn et a!., J. Phys. C21 L931 (1988) [8] H.U. Rahman and W.A. Runciman, J. Phys. Chem. Solids 27,1833 (1966) [9] S. Kern et al., J. Appl. Phys. 63,3598 (1988) [10] S. Kern et al., to be published (1989) 63 ELECTRONIC STRUCTURE OF NEUTRAL ACTINIDES AND THEIR METALS S. Imoto Fukui Institute of Technology, Gakuen 3-6-1, Fukui (910), JAPAN Promotion energy .from fN+*s* to fNds^ was calculated by the intermediate coupling scheme for each or the neutral actinides from Ac to No. Two-electron radial integrals and spin-orbit coupling constants used as parameters were assumed to obey simple relations, mostly having a linear relationship with the atomic number. The calculated values agreed well with the observed except Th and Pa and reproduced the sharp discontinuity between Am and Cm. Calculation also showed that the energy difference between fN+l and fw, where interaction of the f-core with other valence electrons was neglected, agreed again with the obvserved difference betweeen fN+ 1s and fMds , and this suggests that the energy differences between these two configurations are mainly described by the locali2ation energy of an f electron. Two configurations, f dsp and fNds , have the equal number of f electrons, and accordingly, additional energy for f electron localization is not necessary for the promotion from one to the other. The energy difference between these two configurations was evaluated by the difference in the lowest diagonal matrix element. The agreement between the calculated and the observed was excellent in spite of lacking of diagonalization. This shows again that the interaction between the f-core and other valence electrons (d,p,s) is rather weak. The values of promotion energy were used to estimate the heat of sublimation of Es, Pm and Md metals by applying Brewer's theory. Estimated values for the trivalent metallic state were 172, 130 and 9 kJ/mol for Es, Fm and Md, respectively (Table 1). Since they are all lower than 190 kJ/mol, which is presumed to be the heat of sublimation for the divalent metallic state, these metals were inferred to be divalent. Thus, Es metal is the beginning of the divalent actinide series. We see a similarity between Cf metal and Pu metal; both metals make the valency change and the lattice expansion on a particular phase transformation. Table 1. Heat of Sublimation and Promotion Energy for the Actinide Met*is tU1 2^ N 2 ЛИ°в £ s f ds corrected cohesive energy Pu ~342 kJ/mol 76 kJ/mol 418 kj/mol Am 284 128 412 Cm 387 0 387 Bk 310 109 419 Cf 196 202 398 ES 172 (est) 232 404 (average) Fm 130 (est) 274 Icalc) 404 ( " ) на 9 (est) 395 (calc) 404 ( " ) 64 iSSTXEATlON OF COVALEHT bFFBCTS IK THE ACTINIDE COUPOUITOS Oil THE 2-5 BASIS OF UOSSBAUER ISOMER SHIFTS DATA J.Jove, Institute Curie, Section de Physique et Chimie, 11 rue Pierre et iUarie Curie, F-75231 Paris Cedex 05, Franoe G.V.Ionova, V.G.Pershina, Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR A model of estimating covalent effects in Hp compounds with different Uganda is presented. A correlation between 5f-orbital populations (fit) and mossbauer isomer shifts (IS) on the nuclei of 237Hp has been done. The following conclusions on the nature of el.eraical bonding An-Hal and An-0 can be made in terms of the suggested model. In actinide fluorides Anb>x, An=U,Hp, Pu and Am (x=3-6), covalent effects increase with the increase in the oxidation state, i.e. when going from Kp(HI) to Np(VI), the bond being more ionic than the Яр-Р one. The calculated 5f-orbital oecupanoies in the neptunium fluorides fully correspond to the measured IS, and they define both qualitative and quantita tive regularity of their changes (Table ). fit for HpF, equal to 2.0 5i-Atomic Orbital Populations in corresponds to that obtained on Actinide Fluorides the basis of the IS experimental data, and this value exceeds pure AILP U Hp Bi Am ionic one (J>t=1) and is less AnFfi 1.36 2.13 2.94 3.76 than that calculated in terms of An?5 1.68 2.56 3.47 4.38 Xjj, -model. It means that not all AnF 4 2.36 з.зо 4.25 5.20 bonding 5f-electrons take part in AnJ?3 3.1? 4.14 5.11 6.09 the formation of the electronic density at the nucleus through their screening. In Np oxygen compounds 5f-orbital oocupanoies decrease and 6d-orbital ones increase when going from Hp(IV) to Up(VII). This corresponds to the higher delocalization of electrons and increasing effects of hybridization in case of higher valent states. In heptunates of Hp(VI) and llp(VII) the more distorted from pure 0^ symmetry is the system the more prominent are covalent effects. In other word in the oxygen compounds of actinides in high and highest oxidation states (U(VI), Np(VI), Np(VII), Pu(VII) and so on) there is always such a type of distortion, whioh will result in increasing oovalenoy in either axial or equatorial direction. In the neptunyl compounds quasimultiplo HpaO bonds are conducive to the greater participation of 5f-eleetrone in chemical bonding and a greater ocoupancy of 5f-A0s in comparison with neptunates. The equatorial Uganda affect the Ano|+eleotronio structure in accordance with either ionio or donor-aooeptor mechanism. In the seoond case (a) {&a—Lx °* &Л 5.3ак. 1607 6S donor or acceptor character of ligand. ?(ВрА1г ,mm/a Finally, both effects- • 40 />РЭ shortening of axial and / lengthening of equatorial • / bonds or lengthening of / axial and shortening of / .0 / equatorial bonds-always result in the same average z ,i Ба»р03 value of the bond distance ' /Y ' Ва^МПрОс^а To investigate the in •"SpFg fluence of equatorial li- 1 2 3 gands we have calculated . *^VPO6 5f 5f 5f 5fV>a 1 L i i I ii the electronic structure -200 0 200 400 fiOO 800 + of Npo| (Hjjp0=1-72 S)and 2 Isomer shifts in the iaovalent neptunium Hp0j,Cl4 -(R„ 0=1.72 and compounds versus calculated electronic Rj,0(д=2.б2 А), Им АО oocu- densities at the nucleus for the ionic confi pancies are in ЯрО,+ - gurations a2.03 „5.69^.08^7, 1?_ „2.11 5.5Sd1.68 Hp0e0l|- - ,4'14 It is obvious, that there is a donation of electron density from Cl~ to Hp ion resulting in the inorease in 5f-A0 population. Ihia process will result in the weakening of the Hp.0 bond. A vacancy on the HpaO bond results in a decrease in its multiplicity and increase in ionioity. Comparing pairs of isovalent species RpOg and NpP we can see the inver sion of electron density:the Яр oxygen compounds are more ionic than fluorides in lover oxidation states, and fluorides in higher ones (Fig.1). It proves to be one of the reasons, why HpF, has been obtained in solid state, and MpOg has not, whereas in the heptavalent state there are compounds with NpOg anions, but NpF7(An*Np, Pu) have not yet been registered. DEL0CALI2AYI0N OF 5f AND 4f ORBITALS IN COMPLEXES 2-6 AND SOLID COMPOUNDS OF ACTINIDES AND LANTHANIDES S.Siekierski, L.fuks and M.Borkowski Institute of Nuclear Chemistry and Technology Oorodna 16, 05-195 Warsaw, Polanri Although the ionic radius of yttrium is very similar to that of holmium, yttrium can occupy almost any position in the lanthsnide series with respect to free energy of complex formation. The itinerant properties of yttrium with respect to AG* and unit cell volumes of isostructural yttrium and lanthanide compounds can be explained by the ligand-deoendent derealization of 4f orbitals in the lanthanide compounds (1,2). Because of greater spa tial extention, the 1igand-dependent derealization of 5f orbitals should be more pronounced than that of 4f orbitals. If so, then stability constants of complexes should be higher and unit cell volumes of isostructural com pounds lower for actinides than for lanthanides of the same electron con figuration, provided a nan-neglible contribution from cavalency to bonding is present. In case of both the stability constants and unit cell volumes, the difference between an ectinide and its lanthanide analogue with respect to electron configuration should critically depend on the electron-donor proper ties*of the ligand or the counter-atom in the lattice The change of the ligand or of the counter-atom should shift a given actinide across the lanthinide series in the direction opposite to that observeo for yttrium. In order to check these presumptions two series o£ investigations were carried out. In the first series the unit cell volumes of isostructural yttrium, lanthanide and actinide compounds reported in literature were compared (3). It has been found that with decreasing electronegativity of the counter-atom each of the actinides studied (U, Np, Pu, Am, Cm, 6k and Cf) moves across the lanthanide series towards heavy lanthanides. Thus, the unit cell volume of hexagonal NpF, is almost the same as that of the isostructural CeF,, whereas in the СЭЕС of the MeAI, intermetallie compound neptunium is an analogue of erbium. In the second series of studies the free energy, enthalpy and entropy of extraction of tervalent Pu(4), Ahi(5), Cm, Cf and У from nitrate and thiacyanate solutions were determined and compared with Lespective ther modynamic functions for lanthanides. It has been presumed that for the hard nitrate ligand the metal-ligand bond should be preaominantly ionic, whereas for the soft thiocyanate ligand a considerable contribution from covalency to bonding should be present. The extractants used were Ado- gen-464 in the nitrate and thiocyanate form and TBP. It has been found, in accordance with the ionic radius, that for the nitrate ligand all the actinides studied resemble light lanthanides with respect to лСе, дн' and лБ", whereas yttrium is a heavy lanthanide. In case of the thiocyanate system the position of actinides in the lanthanide series with respect to дН* and дЗ* of extraction is between Pm and Ho, depending on the actinide. However, each actinide is slightly heavier pseudolanthanide with respect 67 to £»S* than дН'. Due ta this difference all the tervalent actinides studied become heavy pseudolanthanides with respect to дБ* of extraction, and may even fall out of the series. In the thiocyanate system yttrium, contrary to actinides» is э lighter pseudolanthanlde with respect to AS* than to ДН', so that it resembles light lanthanides with respect to UC The itinerant behaviour of actinides within the lanthanlde series with respect to fi.Gg of complex formation and unit cell volumes, opposite to that observed for yttrium, is a strong evidence for greater derealization of 5f than 4f orbitals. References 1 S.Siekierski, J. Solid. State Chem., 21 (1*81) 279 2 S.Siekierski, Radiochem. Radioanal. Lett., £B С1981? 20 3 S.Siekierski, Inorg. Chim. Acta, Ш. (1988) 301 4 L.Fuks, S.Siekierski, Radiochem. Radioanal. Lett,, I OB (1?B6) 139 5 T.J.M.Alzuhairi, S.Siekierski, Radiochem. Radioanal. Lett., Ь1_ (1983)301 68 ELECTRONIC STRUCTURE, CHEMICAL BOMBING AHD HACHETIC PROPERTIKS I g_? OF ACTIMIDE METALS АШ> THEIR HBPRAOTQRY PHASES I Z V.P.Antropov, I.V.Solovyev, A.I. Liechtenstein, V.A.Gubanov, Institute of Chemistry, Ural Branoh of the USSR Aoademy of Sciences, Sverdlovsk, USSR The electronic structure, chemical bonding, magnetic and cohesive proper ties of the ideal and some defect nitrides, carbides and oxides of actinide metals are investigated. We have analysed simultaneous influence of spin-polarization and spin-or bital coupling on equilibrium properties of these compounds and developed the new approach talcing into account both Interactions simultaneously. The calculations of equilibrium lattice constant have showen that in the case of nitrides and carbides a marked difference between the theoretical end experimental values for light transuranium compounds (Th-V) occurs. For heavy actiniae (Np-Am) compounds the magnetic relatlvistic LMTO-oaluclations predict the lattice constants with the precision of 2-3%. In the framework of soalar-relatlviatlc and full-relativistic approaches we have studied magnetio properties of carbides, nitrides of U, Np end some uranium oxides. The aoalar-relativistio calculations predict most stable magnetio structure (HI for KpC, NpN; АИ1 for UN, UOg;non-magnetic one for UC) correctly, however the values of equilibrium magnetic moment appear to be quite far from the experimental one' в both for BW phase and for ATX phase. Besides dixeot analysis of total energy for the different phases we have calculated the effeotlve exchange parameters of Helsenberg hamiltonian J /l7 for these compounds. Its sign confirms stability of AffM-ordering for UN and UOj, where JQ >0, while for Ш phase Je< 0. Thus, the approach proposed in £\f appears to be useful for actinolde caee also. •agnatic relativlstlc calculations have showen that the influence of spin- orbit interaction on the value of spin moment is quite insignificant (see Table). More essential is the appearance of significant orbital moment for transuranium metals, which is polarized antiparallel to the spin moment. As a result, the total magnetic moment decreases more essentially for nitrides than for carbides (in spite of the faot that the absolute values LE and Mz for nitrides are greater than for oexbldeel.lt can be qualitatively explained why experimentally observed equilibrium moment for NpN is smaller than for BpC. The systematic comparison of theoretical results with ultraviolet and x«ray-photoelectron spectra of core and valence levels have been performed. The Values of Equilibrium Magnetio Moment for U and Np Compounds UN яре NpN fm arm м (n^) exp. 0.75 2.1 1.4 Hz (sc.-rel.) 0.9 1.1 2.6 з.о Hs (rel.) 0.9 2.3 2.6 \ (rel.) 1.3 -2.5 2.9 Reference 1. Liechtenstein A.I. et al. // J.Magn. Hagn. Hater. 1987. Vol. 67. P. 65. «9 INVESTIGATION OP THE CORRELATIONS BETWEEN MAGNETIC POLARIZATION I——_1 EFFECTS AND SPIN-ORBITAL COUPLING IN ACTINIDESs SELF-CONSISTENT 1 " I RELATIVISTIC SPIN-POLARIZED LMTO CALCULATIONS I.V.Solovyuv, A.I.Liechtenstein, A.B.Shiok, V.P.Antropov, V.A.Gubanov. Institute of Chemistry, Ural Branch of the USSR Academy of Sciences, Sverdlovsk, USSR The theoretical description of energy band structure of actinide metals and their compounds is only possible with the help of rigorous treatment both re- lativiatic effects and magnetic interactions in the partially filled 5f-shell. In the present paper the new self-consistent method for electronic structure calculations with sik._"_tanoous account of magnetic polarization effects and spin-orbital coupling has been proposed. This approach is based on the so lution of Dirac equation for a s^ in-dependent potential including effective intraatomic magnetic field. In order to investigate the energy spectrum of a crystal with 5f-elements we used the linearized muffin-tin orbltals (IMTOi method which allows to obtain the two-site Hamiltonian even in the ease of non-diagonal relativiatic spin-polarized single-site scattering t-matrix: fl(k) = Ф + fi+(S - S(lc))-1fi, where V, R, Q are potential parameters which are matrices In the 1, m, о space in contrast to the ordinary non-relatlvlstic or non-magnetic LUTO app roaches, where they are 1-dependent numbers; S(k) is struoture oonstant matrix. The charge and the spin density for actinide metcls ore obtained on the basis of Green functions for this Hamiltonian. New spin-dependent potentials for the self-consistent band scheme are calculated in the local spin-density functional approximation of von Berth and Hedin. The approach developed allows to investigate not only the value of the spin moment but also the value and direction of the .average orbital moment, thus obtaining the total magnetic moment. The method of first-principle investigations of magneto-crystalline anisotropy effeots based on explicit first-Oder variational of the total energy with the rotation of magnetic axis was discussed. We performed the scalar-relativlstlc and relativistic spin-polarized LMTO calculations of the actinide metals electronic struoture (Th,Pa,U,Np,Pu,Am,Cm, Bk). It was shown that consistent account of relativistic effects leads to non-magnetic ground states of Pa,U,Sp, and o(_-Pu at the experimental crystal volume, in contrast to the scalar-relativistic results. The formation and the change of magnetic moment in fcc-phase of Fu via the J. - S transition was in vestigated. The results of the self-consistent band calculations of spin and orbital magnetic moments of actinide metals are given in the Table. Compa rison with the 3d-metals makes the importance of spin-orbital coupling in 5f- systems clear. The change and relative direction of M- with respect to Mg through the actinide series are in agreement with available experimental data. Calculated Values of Spin (Ms) and orbital (M.) Moments Metal Pu Am Cm Bk , Fe Co N1 Ms ( /»ъ ) 4.51 6.52 6.68 5.50 2.22 1.59 0.60 "L <• /ч) -2.40 -0.89 0.18 2.36 0.04 0.09 0.05 70 THE CALCUIASIQH OF THE EJJHRGY DIFFERENCES BETWEEN SOME ELECIROBIOr OOIIPIGURATIOBS 0? THE AOTIMIDE ATOMS AJTO IOHS "U' ~9 V.G.VoIthmin and Q.V.Ionova, Institute of Physioal Chemistry of the Academy of Sciences of the USSR, Moscow, USSR It la known that the energy difference a between various electronic confi gurations of the actinide atoms and ions are measured only for a part of the actiniue series» For the rest of the actinides the energy differences are defined with the use of the thermodynamic data on the enthalpy of sublimation of the actinide metals or calculated through the parameters obtained by identification of the f-f spectra. It is of interest to ceJ.cuO.ate the energy differences for all members of the actinide series directly- through the experimental values of these characteristics known for borne members of the series* We have considered the energy differences E#__ of the 5f —6d transitions in the neutral actinide atoms and in the ions An*t In the calculations the following approximations were used: a) the energies of the core and one- electron interactions were supposed to very smoothly across the actinide series; Ъ) the binding of the 5f and 6d electrons was believed to be small. The calculations are baaed on the solution of the inverse problems, so that the calculated values of E.^ for all members of the actinide aeries are expressed directly through the experimental values of Ef„H known for some actinide atoms and ions. The results of the calculations allow to improve the previously obtained values of Е^н* ELECTRONIC STRUCTURE OP SUPERHEAVY БЬИШИВ ADD THEIR COMPOUNDS 2-10 V.G.Fershlna, O.V.Ionova, N.I.Suraeva. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Mosoow, USSR It is known that close to the end of the Periodic Table relatlvletio effects begin to play s more important role influencing the electronic struc ture of heavy atoms and molecules and as в result the chemistry of their com pounds.There Is в following tendency In this direetlontthe stabilization of 7p and destBDillzatlon of 6d-atomic orbltsle (ДО).Thus,the promotion energi es 5f47sa—-5f47a7p for the elements at the end of the actinide aeries are lower than those for 5f*7e2-—5f47e6d excitation /U.This qualitative effect transforms Into a quantitative one,that takes place in case of Lr.Multioonfi- gurational relatlviatic Dirac-Foek calculations /27 have predicted the 5f 7s 7р.. ,g-electronic ground state configuration which arises from a strong re- lativistic stabilization of the 7pw2-orbital. All mentioned can be valid for Xu also.Thus,recent multiconfigurational Dirac-Foek calculations 05] have predicted that the ground state of KJ is the J»8 state with the main contribution from 7s'6d7p single configuration, nevertheless Lr and Ku can hardly he refered to as purs p or d-elements.The peculiarity of the p-elements is a high promotion energy to d-etate,and that of d-elements ie.on the contrary,a high promotion energy to p-state.E.g.,Fb has first excited 6вг6р7в state at 35500 above the ground state,and E,pV HfCLi| KuCLlf PfaCLzi the loweBt d-s*ate лу (6s26p6d) at 38300 RX*. ЯХ* RXi-SO l\APv. cm" .Nevertheless the first excited —— 5t, state 6a5d3 of Rf is -1 14500 cm above the за. and p-atate is at ev -5 en higher energies. But a number of re cent calculations of the electronic struc ture of Ku in terms of different approa ches has given seve 2a, ral close-spaoed ele ctronic configuratio -20 ns (7s26dZ,7sZ6d7p, 7sa7p2). Fig,1. The energy level sets for HfCl., -30 KuCl4 and РЬС14. ДВ- energy gap between bonding and antibon- ,_»v dlng molecular orbl- T tale. 72 To eay what properties (p or d) Ku will have ill Its compounds la possible on tbe basis of molecular calculations,With that end in view we have calcu lated the electronic structure of KuCl. which seems to be the most proper species,for both d and p-eleirante form rather stable tetrachlorides (HfCl. and PbCl.) whose electronic structure have been also calculated»All the cal culations have been done using the self-consistent field multiple scatteri ng code with ZeC-exchange. Pig.1 represents the energy level diagram as a result of tbe ealculati- ons.lt is seen that antihonding energy level ordering in HfCl. corresponds to a classical splitting of d-orbitals (into eft and t_ -components) in T^- field symmetry. Tbe PbCl. has also an energy level scheme peculiar for the p-element compounds,which is characterized by the first antibonding level of a^-symmetry (below t«-level of pure p-oharaeter).One can see that ae far as antiboriding levels are concerned the KuCl^ is an intermediate case,when a.-level is below both e and tg-levele of d-charaoter.Comparing nonrelati- vistic and relativistie results we can conclude that a dramatic lowarlAg Of 4e1-level ie due to a strong relativistlo stabilization of 7s-A0.Tbus the electronic structure of KuCl. bas an element peculiar for p-element compo unds. (The ordering cf bonding levels for HfCl, and KuCl, is the same). By molecular orbltcl composition and charge-density distribution KuCl. is more similar to HfCl. than to PbCl^ though with a slightly more promi nent p-obaracter.But we can hardly speak about a full analogy of HfCl. and KuGl. because tbe latter will differ by its spectral properties which are influenced by the energy level ordering. References 1. Ionova fl.V. et al.,//Radiokbimiya.1984.Vol.36.P.431. 8. Desclaux J.P..Pricks B.//J.Fhys. 19S0.Vol.41.P.943. 3. Glebov V.A.,et el.//Preprint JHffi.Dubne.E6 88-201.1988. TIME OF FLIGHT NEUTHON INELASTIC SCATTERING ON COMPOUNDS [ . OF TETRAVALENT THORIUM AND URANISM by Edgar Soulie and Hubert Marquet-Ellis CEA CEN/SACLAY DLPC/SCM UBA CNBS 331 91191 Gif sur Yvette Cedex - France and Gerrit Coddens Laboratoire Leon Brillouin Centre d'Etudes Nucleaires de Saclay 91191 Gif sur Yvette Cedex Prediction of an excited electronic energy level at about 8 cm"1 above the ground level for the compound U(NCS)8[N(C2H5)i|]f| prompted the reported experiment. With a neutron beam of wavelength 6 A, and a sample cooled at 1,6 kelvin, an inelastic peak was observed at circa 12 cm"1 for both U(NCS)g[N(C2H^)i,)4 and Th(NCS)8[N{C2H5>i|]!t. This peak was also observed on ThClg[N(C2H^)l)]2- It is ascribed to a tunnel effect between two positions. Each of these is occupied with a 0.5 occupation factor by a carbon atom of the methylene moiety. This interpretation is consistent with the sharp decrease of the intensity of the inelastic peak as the diffusion angle increases. THE ELECTRONIC STRUCTURE OF TRIS(CYCLOPENTADIENYL)-URANIUH(IV) CHLORIDE 2_l2 IN THE f-f RANGE H.-D. Amberger and H. Reddmann, Institut fur Anorganische und Angewandte Chemie der Universitat Hamburg, Martin-Luther-Кing-Platz 6, D-2000 Hamburg 13, F.R.G. N.H. Edelstein, Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory, University of California. Berkeley, CA 94720, U.S.A. During the latest decades numerous physico-chemical measurements as well as supporting quantum chemical calculations have been performed in order to elucidate the electronic structure of tris(cyclopentadienyl)-uranium(IV) chloride (Cp^UCl). The electronic structure in the range 6.9 - 10.5 BV could be solved by comparing the re sults of He(I)/Ha(II) UV photoelectron spectroscopic measurements ltd non-relativistic dis crete variational X^ calculations fl]. Likewise the crystal field t-F) splitting pattern in the low-energy range up to 45Q era- as concluded from paramagnetic susceptibility measure ments of powders И and "hot" transitions in the absorption spectrun J3j, respectively, is meanwhile generally accepted [4j. Up to now, the optical spectrum of Cp„UCl in the f-f range has been studied in solution or as polycrystalline powders. Thus, the additional information which could be obtained from single crystal measurements was missing. For this reason there was little progress with interpretation of these data. Recently we demonstrated by means of some organometallics of the lanthanides that even in solution valuable information on the nature of CF states may be provided by the tech nique of magnetic circular dichroism (HCD) spectroscopy Rft. Applying this method to Ccp3U(NCS)2"]~ and [Cp3U(NCBH3)^)~, where energetically isolated CF ground states of fj symmetry exist, some 20 CF states could be assigned [6j. In the case of Cp„UCl, however, the CF ground state is separated only some 200 cm- from the first excited state [2-43, and quite a lot of "cold" rnd "hot" transitions coincide accidentally at aiibient temperature. Thus, it is very difficult to recognize the type of the arising Faraday terms in the MCO spectrum run at room temperature. Frequently, glassy freezing organic inert solvents like isapentene or methylcyclohexane are used to study low temperature MCO spectra of organometallics. Unfortunately, the solubility of CpqUCl in these solvents is not sufficient. Using mixtures of methylcyclohexane and toluene of the ratio 1:1 numerous transitions in the HCD spectrum (recorded at some 150 K) could be identified. The parameters of an empirical Hamiltonian were fitted to the thus derived CF splitting pattern. The obtained free ion parameters are discussed in terms of covalency. Deferences 1- A. Vittadini, H. Casarin. D. Ajo. R. Bertoncello, E. Ciliberto, A. Gulino. and I. Fragals, Inorg. Chim. Acta 121, 123 (1986). 2. С Aderhold, F. Baumgartner, E, Oornberger, and 6. Kanellakopulos, Z. Naturforsch. Teil A, 33, 1268 (1978). 3- H.-D. Amberger. J. Organamet. Chem. 116, 219 (1976). 4. H.-D. Amberger, H. Reddmann, and N.H. Edelstein, Inorg. Chin. Acta 141, 313 (1986). 5. H.-D. Amberger, H. Jahn, and N.H. Edelstein, Spectrochim. Acta 41A, 465 (1985). 6. H.-D. Ambergsr, H. Reddmann, 6. Shalimoff, and N.H, Edelstein, Inorg. Chim. Acta 139, 335 (1987). 75 шшш, coKpomros АШ> COMPLETES: KLECTROHIC STRUCTURE, СШ-ЩСАЪ Г I BJHDIlie JOT) SPEOTRAb PROPERTIES I ~ I M.V.Ryzhkov, V.A.Oubanov. Institute of Chemistry, Oral Branch of the TJSSE Academy of Sciences, Sverdlovsk, USSR Recent progress In quantum-chemical methods for calculations of electronic structure of molecules, complexes and solids, as well as considerable In crease in computers efficiency create tho base for theoretical modeling of physical and chemical properties of the heavy element systems such as uranyl oompounde and complexes* In present work the investigations of solid compounds Jf-DO-, O^tlOgCl., OO-F. and complexes Oo|+ and 002^"°3^22B20 havs oeen carried out with the use of Relativistic Discrete Variational method (ДОГ) £l"]. The HDV approach is based on: 1) the solvation of Dirac-Slater equation for four-component spi- nors, whioh traneform according to irreducible representations of double point symmetry groups; ii) local approximation of exchange and correlation potential and 111) numerical diophantlne integration in matrix element calcu lations. The main attention in electron energy spectra and the structure of one- electron states was paid to the valence band and deeper orbltr"s in the re gion of U6p-02s -levels. She considerable influence of the U5f, tJ6p coupling with na- and np-orhltals of uranyl oxygens as well as of uranium atom neigh bours in equatorial plane, on the shape of these bands and charge density distribution have been obtained. The calculated values of overlap populations have been used for the analysis of bond order and relative contributions to bonding from different orbitals of uranium* atom and Uganda. We have found that the 5f-atates participation Is chemical bonding is noticeably greater, than was usually supposed recently. The general structure of interatomic bonds in all uranyl systems was also obtained in our calculations. The information obtained on the energy level structure and the composition of molecular orbitals has permit to caloulate approximately the theoretical photoeleetron spectra of some uranyl oompound*. The contributions of the mo- leoular orbitals to thn theoretioal spectrum have been found acoordlng to Helius-type expression [г] with the use of aubshell photolonisation orosa- eections [3]. She details of excitation process of different electron states, belonging to uranyl and nearest neighbours of 5f-elemeat in equatorial plane, have been investigated on the base of transition state method. Theoretical results were compared with experimental x-ray photoeleetron speotra of uranyl oompounde [4]. A good agreement of calculated one-eleetron energies with the relative positions of experimental spectra subheads oonflnu the reliability of our approach for the investigation of actinlde metal ooapounda. Referenoes 1. Boson A.. Sills B.B.// J. Cham. PAya. 1975. Vol. 62. Р.ЗОЭ9. 2. Hellus &. Electron Spectroscopy. Amsterdam, London: Xorth-Holland, 1972. 3. Scofleld J.H.// J, Bleotron Spectrose. 1976. Vol.8. P.129. 4. Teterin Yu.A. et al.// Docklady Acad. Hauk USSR. 1985. Vol.284. P.915. 76 ANGULAR OVERLAP MODEL IHTBRPHEMTIO» OF I)«B1ASTIC НИШИ» SCATTBRUKS IBAHSITIOHS FOB. UX-, Z • CI, Br, I Z.GaJek, J.Hulak, Institute for Low Temperature and Structure Research, Pollen Academy of Sciences, 50-950 Worclaw, P.O.Box 937.Poland Interpretation of the recent Inelaatio Neutron Scattering (UTS) studies on the H*+ Ion la the OT, oompounds, where X • 01, Br, I /1—47 is crucial for understanding their Intriguing nagnetlo properties. The present dlaouaalon of the Ig/S(5f ) ground state splitting In this homologous aeries bases on the Angular Overlap Model (А0И). It reveals a large flexibility of the INS data for different formally acceptable interpretations. The leaat square fittings of the AOH parameters to the observed energy Intervals shown in the Table have been obtained within the simplified version of AOH Including some inborn physloal lio'tattone of the model, proved previously for IP* compounds /5/. Table. The AOH parameters fitted to the INS transitions (gives In the parentheses) and the corresponding energy levels and crystal field parameters B8 /aeV/ Energy levels «V «te •S во Bo B0 \4 UC13 58(57) 56(57) 33(34) 30(-) 72 27 5 42 -юз -152 -104 -106 UBr3 46(46) 42(42) 27(-) 26(27) 57 22 3 33 -106 81 «g 37(37) 35(37) 26(25) 17(16) 57 21 8 -10 -13 3 14 The remaining CPP's are: B? » -16, B| • 1, Bj . -117, B| » 70. •!- -28. From the Table one oan learn the expected regularity of both the calculat ed ejn parametera and the resulting sequences of levels. It refleots the anti cipated decrease of the orystal field strenght along the UX. series, "Phe re sults for UC1, are consistent with the available Interpretation of the opti cal speotra of U3+i LaCl, and the data extrapolated from the HdCl- study. They also confirm the original ins Interpretation, unfortunately, the two re maining homologous coapcunds are not the oase. Their interpretation given by Muraslk et al. /2-47 is not to be reconciled with the AOH approach. The latter other available experimental data do not allow one to settle the oontroversy. Slnoe the IBS Interpretation seems to be, from the AOH point of view, defi nitely artificial it would be reeomended for experimentalists to look for a new interpretation being in line for UX- aeries. Acknowledgements- We are indebted to Dr A.Huraolk for providing the data for 01. prior to tbr, publication and to Dr R. Lyzwa for Inspiring disauseiona. References 1. auraslk A., Fisher P., Purrer A., Szozepaniak W. // J. Phys. Ct Solid State Phys. 1985. Vol. 18. P. 2909. 2. Huraalk A., Purrer A., Szozopanlak W.. // Solid State Commun.. 1980.1980. Vol. 33. P. 1217. 3. Hurasik A., Purrer A., Fisher P., Szezapanlak V. // 17emea Journees dee Aotlnides, Switzerland 1987, Abstraot Booklet. P. 55. 4. Huraellt A., private communication. 5. Gajek Z., Hubert S., Xrupa J. // J. Magn. Hagn. Hat. 1988. N 76/77. 77 ON ТНК 25 К PHASE TRANSITION IN HpOgi ЕУЕВОТ OF JAHN-TELLER LATTICE |~ 15 DISTORTIONS AND QUADRUPOLAfi ORDERING I—'. 0 V.S.Mironov. Institute of Physical Ohemletry of the Academy of Sciences of the USSR, Moscow, USSR A fi rat-order phase transition occurring at TQ= 25*4 К in cubic NpO^ {CaFp-type structure) мае being studied in-numerous experimental and theoreti cal investigations £}-%/• In spite of these efforts the nature of this phase transition is still uncertain: magnetic susceptibility measurements indicate antiferromagnet-llke behaviour of %(T), but both neutron diffraction experi ments and Kosabauer studies did not reveal any magnetic ordering in SpOp be low T /3-4/. The upper limit of magnetic moment of Np (5f ) was found to be 237 only 0,01^ /57. ^om ^'Hwp Mossbauer studies of RpOg in external magnetic fields a spin-glass state in low-temperature phase wae ruled out /3/. Two explanations of anomalous magnetic properties in NpO« was earler sug gested: a) a quenchitg of the magnetic moment of Np4+ to a nearly zero value caused by a local Jahn-Teller distortions C^I* or b) a quadrupolar ordering of IQ quartet ground states of Np4+/V- Both suggestions are theoretically analyzed in this report. For realisation of the Jahn-Teller quenching mechanism it's necessary that g-tenaor of the lowest Kramers doublet (which arises from the splitting of If} quartet ground state of Np*+ when local cubic symmetry lowers) should turn to вето (g - g_« gz« 0)» For this purpose the dependence of g , a , and gz on local Jahn-Teller modes of e , til', and t^j'symmetries (see Fig. 1) was calculated. From analysis of corresponding equations one can show that no combination of the Jahn-Teller modes exists which simultaneously turns to zero all three values g_., g_, and g_. Therefore one can conclude that any local distortion in cubic unit HpOg fails to quench the magnetic moment of Np ion in low-temperature phase of lipOg. Further, similar results were obtained for quadrupolar ordering mechanism, From theoretical consideration in a mean-field approximation one can deduce that any kind of quadrupolar ordering is unable to provide completele freezing of the magnetic moments of Kp * To summarize, it was demonstrated in this report that both Jahn-Teller effect and quadrupo Local Jahn-Telle- r modes lar ordering of the Np electronic states did Q± in cubic unit HpOg not provide an explanation ot the phase transiti in NpOp crystal on in NpOg- Some possible types of special magne- tic transitions in HpOg due to essential non-Heisenberg exchange interact!- ons between Hp ions were discussed. Referenees 1. Erdoo P., Solt G., Zolnierek Z., Blaise A., Founder J.M.//Physica. 1980. Vol.102B. P.164. 2. Ross J.W., Lai D.J.//J. Appl. Phys. 1967. Vol.38. P.H51. 3. Delapalme A. et al./'Physica. 1980. Vol.lOZB. P.171. 4. Priedt J.K., Lltterst P.J., Reblzant J.//Phys. Rev. В. 198$. Vol.32.p.257. 78 COMPRESSION STUDIES UP TO 55 GPa ON NaCl TYPE COMPOUNDS AnX : An = Np, Pu and X = Sb, Те S. DABOS-SEIGNON1, U. BENEDICT2, J.C. SPIRLET2 and M. PAGES1 1 Institut Curie, Section de Physique et Chimie, Physicochimie des Elements Transuraniens, UA D 0448 CNRS, 11 rue Pierre et Marie Curie, F-75231 Paris, Cedex 05 2 Commission of the European Communities, Joint Research Centre, European Institute for Transuranium Elements, Postfach 2340, D-7500 Karlsruhe 1 This work is a part of a systematic study on the behaviour under high pressure of isostructural binary 1:1 actinide compounds. These studies were undertaken in order to understand the influence of the Sf electrons on the chemical bond. The degree of localisation of the Sf electrons is related to the interactinide spacing, to the crystal symmetry (delocalised 5f electrons favour distorted, low symmetry structures, while localised 5f electrons prefer symmetric structures) and to the ligand, At ambient pressure, the neptunium and plutonium antimonides and tellurides have a NaCl type structure and their 5f electrons do not enter the conduction band. Applying pressure to a material leads to electronic and structural transformations. In the case of the actinides and their compounds, due to the strong correlation between the crystal symmetry and the Sf electron configuration, the phase transition we can Observe by X- ray diffraction, may be influenced by a decrease of Sf localisation through the decrease of interatomic spacing. The present study of the behaviour under pressure of monoantimonides and monotellurides of Np and Pu would allow to study the influence of the ligands Те and Sb (of comparable ionic radius) and of the actinide element on the Sf electrons' behaviour under pressure. The compounds were synthesized by reaction of the elements which are heated in a vacuum sealed quartz tube to about 600°C; the resulting powder was then transformed into single crystals by mineralisation [1]. The lattice parameters of the samples were determined by precision x-ray diffractometry or from a Debye-Scherrer pattern. High pressure studies were performed at room temperature using a diamond anvil cell of Syassen-Holzapfel type. The sample, finely ground, was loaded in a 0.2 mm diameter hole of an Inconel gasket inside the pressure cell. The pressure was measured "in situ" according to the ruby fluorescence method [2J. by means of a small ruby splinter placed within the sample. Silicone oil was used as a pressure medium to allow for hydrostatic conditions. The x-ray 79 diffraction analysis was performed in an energy dispersive x-ray facility using a double- conical-slit assembly which fixes two Bragg angles to about 5* and 7" [3]. Studied up to respectively SI GPa and 47 GPa, NpTe and PuTe both undergo a first order phase transition to a primitive cubic cell of the CsCI type structure at respectively 13 and 15 GPa. In the case of the antimonide compounds, the NpSb, studied up to 52 GPa, transforms above 10 GPa to a tetragonal structure, space group P4/mmm. This tetragonal phase can be regarded as a distorted CsCI structure while the atomic positions are the same as in the cubic "CsCI" cell. With PuSb, two first order transitions are observed. The first one is the conventional NaCI to CsCI type structure around 17 GPa, then the NpSb type transition is occurring above 42 GPa and is maintained up to 57 GPa, highest pressure reached in this study. Upon releasing pressure, strong hysteresis of the inverse transformations are observed, down to 2 GPa ( monotellurides), 4 GPa (NpSb) and 32 and 4 GPa for PuSb. Compressibility of the low pressure phase was determined by fitting the V(p) d?ta 'o the Birch [4] and Murnaghan [5] equations. Results are compared with those obtained for analogous uranium and thorium compounds [6, 7, 8, 9], and discussion is made on the nature of phase transition, the stability pressure range of the observed phases and the bulk modulus, according to the influence of the actinide element and the ligand in term of degree of localisation of the 5f electrons. REFERENCES [I] I.C. Spirlet, O. Vogt, in Handbook on the Physics and Chemistry of the Actinides, eds A.J. Freeman, G.H. Lander, Elsevier Science Publishers, B.V, 1984, p. 79. [2] HJC. Mao, P.M Bell, J.W. Shaner, D.J. Steinberg, J. Appl. Phys., 49, 1978, 3276. (3] U. Benedict, C. Dufour, High temperatures - High pressures, 16, 1984, 501. (4] F. Birch, Phys. Rev., 71, 1047, 809. [5] F. Murnaghan, Am. J. Math., 4 80 VIBRONIC STRUCTURES OF PLUTONIUM HEXAFLUORIDE IN THE VISIBLE SPECTRAL REGION 2-17 К. С Kin Los Alamos National Laboratory Los Alamos, New Mexico, 87544 USA As one of the most abundant actinides and one of the most important energy sources, Plutonium has been the subject of intense scientific investigation around the world. The availability of large quantities also affords the opportunity of studying the element in various chemical forms. In recent years we, at Los Alamos, have made substantial progress in the study of molecular properties of Plutonium hexafluoride. By utilizing modern spectroscopic tools and techniques, we have recorded detailed spectroscopic features of the vibronic bands in the visible region. A combined use of high-resolution laser devices and Fourier transform spectrometer enabled us to obtain a complete survey spectrum of the entire vibronic band systems and also some specific rovibrational structures in a selected band. Following a brief review of the nature of vibronic transitions in actinide hexafluorides, the results will be presented of our spectroscopic assignments and the most accurately measured vibronic energy levels. 6.3м. 1607 SURFACE ELECTRONIC STRUCTURE OF PLUTONIUM I 8emard R. Cooper " Sept. of Physics, Meet Virginia University*. Horgantown, WV 26506, U.S.A. end Center for Materials Sciences» Los Alemoe National Laboratoryt, Los UBBOB. New Mexico 97545, U.S.A. You-Gong Hao Dept. of Physics, Wast Virginia University*, Morgantawn, WV 26506, U.S.A. Gayanath W. Fernanda Physics Dept., Brooktmven National laboratoryt, Upton, NY 11973, U.S.A. We have calculated the surface electronic structure of plutonium using our self- consistent Film Linearized Kuffln-Tin Orbital (FLMTO) method for a (lll)-oriented five- layer slab-geometry. We believe this is the first self-consistent all-electron surface electronic structure calculation for an actinide system. The interest and difficulty of dealing with actinide electronic structure is associated with the large number of electrons in the atom, the importance of relativlstlc effects, and especially the behavior of the 5f electrons which typically are intermediate between itinerant and localized. The ultimate motivation for the present calculations lies in two directions: (1) gaining information pertinent со dealing with chemical reactivity questions via chemisorption studies, (2) gaining information pertinent to understanding of stabilisation of crystallographic structure via epitaxial growth stabilization and structural reversion studies. The calculated work function is strongly affected by the treatment of the 6p electrons, which are semicore states. Kith the 6p electrons treated as core, including spin-orbit coupling effects, our calculated work function for plutonium is 4.3 eV in good agreement with experimental values of 3.4 to 4.3 eV for uranium. A striking feature of the layer-projected density of states (DOS) is that the surface DOS peak width is not such narrower than the interior bulklike DOS peak width. This seems to suggest that the hybridization of the partially itinersii? f electrons with s and d banJ electrons Is able to accomodate to the change in coordination on going from the interior to the surface. Our next project In this line ol research is to calculate the surface behavior of plutonlum hydride, and we have initiated auch a study. We will discuss results of that study as available. «Supported by U.S. Dept. of Energy-Office of Basic Energy Sciences Grant DE-FG05-84ER45134. tSupporfced by U.S. Dept. of Energy. 82 ELECTRONIC STRUCTURE AMD PROPERTIES OF THB BIVALENT PLUTONIUM HALIDES V.K.Mikhalko, T.V.Mlkhalina, S.V.Ionova. Institute of Physical Chemistry of the Academy of Solenees of the USSR, MOBOOW, USSR The compounds of the divalent lauthwnides and ectlnldes are usually тегу unstable and show tbe tendency to oxidation or disproportionation. Predictions concerning tbe possibility of obtaining! the stability and tbe physico-chemical properties of these compounds are ot great Importance. We have calculated the oleotronlo structure and properties of the Plutonium halide molecules PuHalg, where Hal « F, CI, Br» and of corres ponding halldee of IIA end IIB group elements ( Ca, Sr, Ba, Zn), assuming both linear and bent geometry. The calculations have been carried out by a modified version of the quasirelativistic self-consistent extended Huckel theory; a valence double zeta baeis was employed. Unlike the previ ous versions of EHT, we computed the nondiagonal matrix elements of tbe crystal field bamiltonlan in point charge approximation. This is essential for the estimation of f-d transition energy. The ground electronic state of the PuPg molecule is found to be the stats with f d configuration of Pua+ ion (in terms of ionic model); the leaBt bound electron is the 6d one. The state with f electronic configu ration is situated 0.1-0.8 eV higher. The main reason for 6d-level depres sion (by 1.1 eV) ie the d-orbital splitting in the 7" ion crystal field. Doing from F to CI and Br, the d-orbital energy increases by 0.5 eV, the more probable electronic configuration of PuBrg being the f one. This trend is found for linear as well as for bent geome ry. The chemical properties of Plutonium in f and f'd configurations differ considerably. In the former ease Fu ressembles alkcline earth elements as to the ionicity and PuHal bond order.atomio orbital populations and elec tronic level structure. The main difference is the presence of easily ionised Sf-eleotrone, resulting in the ready oxidation of the divalent Plutonium. The PuHalg ionisation potential and eo the redox potential of Pu-'+/Pu2+ couple do not change considerably in going to the f'd configuration: the calculated valu.9 of the PuFg LP. is 6.7-7.0 eV for both configurations in comparison with the experimental value of 6.4+0.3 eV. However, the atomic charges decrease and the orbital and bond populations increase strongly. In other words, the electron aoceptor properties of the Pu2+ ion in f5d configuration are much more pronounced, even in comparison with the zlno group elements. It is shown that the 6d electron in the Plutonium ion makes the forma tion of diners and clusters with metal-metal bond possible which in turn can give rise to extra stabilisation of f'd eleotronic configuration of the Pu2* ion. 83 OPnCALANDEPRSPECrRAOFTRIVALENTACHNmESDll.inEDINLiiro4 | ~—I N.E*btein,W.Krx,D.Pk^.G.Starimc«,D.B*—' Lawrence Berkeley Laboratory, Berkeley, СаШоггиа 94720 USA, and MM. Abraham, C.B. Finch, and L.A. Boamer. Solid Stare Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 USA Optical spectra and Ike парей: properties of the lamrumdeirKBtU^aiiaKl in YPQ4 and/or Ы>04 have been the object of numerous studies. 1л addition, the lanthanide phosphates heavier than GdPOa (Tb through Ln) crystallize in die tetragonal form (as does YPOa) and have been examined opdcally and mapelkaUy as рше single crysnh. Thus a great deal of taformarion is available about the entity teveb and the tree ion and crystal-field parameters of the entire lMthamle series in tetrarjmal phosphate crystals [l]. WehavcrxgmtoexamiiKiJiemvtlentacBnidefAri^Honsdu^ To date, M single crystals with Я7^,24гл,Шд,гьг44от1М8сш, and *Cf in concentrations of-0.1 - lmole% have been grown. Unfortunately, the Np and Pu crystals have both the trivalem and tbe retravalent oxidation staie«r«eserjt,vdikAn^crrieo|rrk^rfflalysee^fkiin. Tie rlPR(elei3rrjnr£ramagnerjc resonance) spectrum of ДОСш/ЦРОа has been measured in great detail and the analysis ofdfe spectrum at room temperature. 77K, and 10K has allowed the delerminirion of the energy leyds of ite ground J=7y2 term at these итрегашгез. Theciy!W-6eldparunerasobtair^fromEPRsr^craat-10K,aIongwithtre tree ion parameters given by СвгшгИ ct аЦ2], give a cakutated energy level spectranwrrklt agrees far%v^ with the measured «bsorptiOT spectrum Ш me NnfflT>krr#ori. EPRandopicatrneasurcrncnison^'COIjiPOjhave begun. Astrrveyoftliecomrderedc9rkalaiidEPRdattcAti>etrivafcnt& rhe results «^гхсоггчшЫю the pubUsrrfdiB от the talhanide ions. Trends in the ftre ion and crystal- field parameters for An5* ions in the tetragonal phc^ate crystals wiU be compared tosiinilar data for the An3* ions in LaCb. Acknowledgement. This work was supported by th? Director, OfHce of Energy Research, Offke of Basic Energy Sciences, Chemical Sciences Division of meUADepasm«Mofaegymio>rOontactNo.DB- AC03-76SF00098 and by the Division of Materials Science, U.S. Department of Energy, under Comma No. DE-AOS гЖЖ21400 with Martin Marietta Energy System, Inc. II] CA. Morrison aMRJ.l^viu, in "Handriook of u^ Physics imdCherrdstry of Rare Ea^ Osehneidec and L. EyriEg, North-Holland Publishing Co, Hew York, 19*2, VoL 5, pp. 609-613. P.C Becker et al., I. Chem. Phys. fit 2872 (1984). P.C. Becker « al., Phys. Rev. В 21,8102 (198Л). O.M. WiIm«iB.«aU"fti«»s*i»ofB«»rjr& Non-Resonant and Near Resonant Excitation", sobmined to Phys. Rev. B. [2] W.T. Camall and H.M. Crosswhite, "Optical Spectra and Electronic Structure of Actiniae Ions in Compounds and in Solution," ANL-84-90,1985. B4 PRECISION MEASUREMENT ИР HYPERFIHE SPLITTING AND ISOTOPE 1 241 Z43 GEE1 oT/g ' °*9/2 ЯИЮИЯЯ Ш Ain ABD Am ATOMS Yu. P. Gangrolcii, I. B. Izoslmov, S. S. Kovalenko, В. Н, Itarkov, A. V. Stepanov, L. A. Fleakaohevskii, A. A. Himekii-Koreakov, S« V« Khlebnikov, S« K. Cherezov, Khlopin Radium Institute, Leningrad, USSR Most investigations of actinide atomic spectra were performed with resolution perceptibly lower than that of laser techniques. We report the first precision measurements of hyperfine structure 8 CUPS) and isotope shift 43) for atomic transition S7/2 ~* ?oy2» Л . 6054 i in 2*1Am and 2*3Am. Atonic transition was excited by a tunable laser, fluoreacesoe was registered by a photomultlplier under photon-counting operation. We have determined HFS constants with quadrupole IQ) and magnetic (fi) moments of nuclei and the value of IS which depends on the variation of mean-squ data have been obtained: 2410 241JY п. 2 s JJJS - 1,10 + 0.02; J^JS = 1.052 + 0.007; ff Hie sensitivity was ~10 nuclei of Am in the sample, and isotope selectivity was ~10"*. The values of HPS in actinides are rather large (the distance between the peaks is 4-6 GHz) which offers the possibility to get information about nuclear moments higher than fl and Q. The ways of obtaining data on "exotic1* nuclear momenta are discussed. DIVALEHT ACTIHIDES AHD LAHTBABIDES WITH THE f°~1d1 г- гг ELECTRON CONFIGURATION NaB.lUkheev, I.A.Rumer, M. Z.Kazakovioh, L.K.Auexman. Institute of Physical Chemistry of the Aoademy of Soienoes of the USSR, lloacow.USSK The determination of the standard oxidation potentials of the palre г+ м'*/Н (Е°мЗ+.„2+) of all the lanthanides and of the great part of aotinldee enabled us to find among them a group of elements, whose Е^З+ум2* praotloal- ly does not depend on the energy of the f-d exoltation of the divalent Ion. These elemente are La. Ce, Gd, lb, Lu - among lanthanldea, Pu and Cm - among aotlnldea. Such independence of Е°н3+л^+ of the energy of the U fd-exol- tatlon Is accounted for by the fact, that Ia?!", Ce2*, Gd8*, To2*, Lu2*, Pu2*, Cm , In contrast to other f-elements In the oxidation state 2+, have the f0"^' configuration, and not the f°d0 one Л7- Some physico-chemical properties of divalent f-eleuents in the f11* d oon- figuration have been studied. The hydration energy has been determined for lanthanides. It bae proved to he higher than that for the same ions in the 0 ^d state £\}r The stabilisation energy is achieved due to the splitting of the d-level In the crystalline field of Uganda. The presense of the unpaired d-eleotron results in the dimeriMtion of Pu and Cm2*, which is accompanied by the additional stabilization of the 2+ oxidation atate. The dlmerlzation energy at 1170ЧК la 0.3-0.4 eV /2,37. The peculiar feature of the elements with the fn"1d1 electron configuration In the 8+ oxidation atate la their ability to form mixed condensed clusters of the *UC1, type, where Ibad, To or Y Л7. Actinides and lanthanides in the ^fndc7'+ state, e.g. americiuo sad europium, do not possess this property. The study of divalent aotinldee with the unusual, f d electron configu ration is a new problem In the ohomtstry of these elements. References 1. Hlkheev N.B., Rumer I.A., Auexman L.BF. // Radloohem. Kadioanal. Letters. 1985. Vol.59, H5-6. P. 317-328. 2. Uikheav И.В., Kazakevloh X. Z. , Huaer I.A. // Radiokhimiya. 1988. Vol. 30, H 2. P. 268-270. 3. Hlkheev И.В., Kazakevieh H.Z., Burner I. A. // Radlokhlmlya. 1988. Vol. 30, H 2. 1. 270-272. 4. Hikheev If. В., Kamenskaya A.N., Burner I.A., K&zakevich H.Z. Ill All-Onion Cent, on Chemistry of Transplutonium Elements. Dmitrovgrad, 1988, Abstr. of papers. P. 54-55. RELATIVIST») BPPBOTS IB KURCHATOVIUM CHEMISTRY I ••••- B.L.Zhuikov. Institute for Nuclear Research of the Academy of Sciences of the USSR, Moscow, HSSS V.A.Glebov, V.S.Nefedov. Ail-Union Research Institute of Inorganic Materials, Moscow, USSR l.Zvara* Joint Institute for Nuclear Research, Dubna, USSR The regularities of the Mendeleev Periodic System suggest that the first transactinide element - kurchatovium (Ku) - should be a chemical hotnologue 2 2 of XI, Zr and Hf, having the d'a' ground-state configuration. However "relativistlc effects" in the electron shells of heavy atoms a. J likely to change to some extent the order of filling the orbitals. An assumption Mas declared /"17, that element 104 (Ku) has the 7s27p2 ground-state level and it should be the p-element probably similar to lead. In order to investigate some possible irregularities in the chemical properties of Ku, caused by relativism, we consider three experimental and theoretical approaches based on the chromatography and thermochromatography of atoms 12/» of higher /Э/ a^d lower halldes, and on the other hand, on relativistic multlconfigura- tlonal Dirao-Pock calculations p>]. Volatility in elemental state. To test the possible volatility of Ku as a homologue of Pb, the chromatographic behaviour of Ku was investigated {2J in a quarts column at 1170°C in the hydrogen carrier gas. The spontaneously fissioning (7%) Ku-259 (T1^g-4-5 s) was produced. No fission events were detected behind the outlet of the column in the fraction of volatile elements* Pb, Та, and Au, while at least 20 or 30 decayB were expected in the case of the high volatility of metallic Ku. And there were 65 s.f. events in the starting part of the column In the Rf plus actlnlde fraction. Prom these data, a lower limit for the sublimation heat of metallic kurchatovium of 370 kj/mol was deduced, in comparison with 180 kj/mol for Pb. In addition, the most accurate relativistic calculations of the electron ic structure of the Ku atom were carried out, taking 468 jj-configurations into account. It was found that the ground state of the Ku atom should be a J*2 level consisting mostly of the odd configurations 80$ 6d7s 7p + 18* 6d27s7p. Ш» 6d27s2 configuration lies 0.5 eV, and the 7e27p2 one 2.9 eV above the ground state. It was shown that the realization of the 6d7s27p ground state la the result of the relativistic stabilization of the 7p1^2 orbital M. The atomic radii calculated for the corresponding configura tions, were found to be 1.30, 1.56, 1.54 and 1-79 A for Ti, Zr, Hf and Ku, respectively. From the comparison of the orbital energies and multielectron levels of Ku and those of the atoms of d- and p-elements in group IV it is concluded that, according to its chemical properties, Ku must belong to typical d-, rather than p-elements. The excited levels in the Ku, atom as well as In li, Zr, Hf, are much closer to the ground state levels as compared to the atoms of p-elementa. As a result, the d-elemente, when farming compounds or condensing to the metallio state, can reach a favourable configuration with out significant expenditures of the promotion energy. This, in particular, B7 explains stronger bonds in d-element compounds and higher heats of sublima tion of the metals* From the correlation between the sublimation heats and the sums of orbital energies of the ground states, which are related to the promotion energies, we estimated the Ku sublimation heat to be close to 510 kj/mol for the calculated 6d7s 7p-ground state, 610 kj/mol for the "nonrelativistic" 6d 7s -ground state (compare with those for Ti, 2r and Hf in the d a ground state: 469, 600 end 620 kj/mol). Ihennochromfttography of tetrahalides. According to our calculations, the average radii of valence orbitals, which correlate well with the experiment- :lly determined ionic radii, are equal to 0.55, 0*70, О.71 and 0.77 A for i, Sr, Hf and Ku, respectively. In accordance with the empirical trends /37» this points to a lower volatility of Ku tetrshalides compared with Zr and Hf halides. However, the sums of orbital energies for Me* (this charge state is close to that occurring in tetrahalide molecules), which define the covalent character and, to a certain extent, the volatility of a compound, change in the different order: М.Э- Ku' Hf 7 Zr. The experimental data on the thermochrouatography of bromides /V seem to correspond to this order. Stability of low oxidation states. This approach may be based on dereali zation of the p-electron in the predicted 6d7e 7p-ground state configuration. According to our calculations, Ku has a low 1st ionization potential - 5.8eV, and a relatively high 2nd one-14.8 eV (those for Hf are 7-5 and 15.0, for zr - 6.9 and 13-1 eV). This should result in greater stability of the lower oxidation states of Ku, especially of monovalent Ku in gaseous binary compounds. In this case, the relativistlc 7p../2~elec*rone ага °* paramount importance in bonding. The experimental verification may be done by a compa rative investigation of the behaviour of Zr, Hf and Ku by the thermochrona- tographic method at high temperatures (> 1500°C) in a zirconium metal column using a mildly chlorinating carrier gaa. She experiments can be carried out at the radioisotopic facility of the Uoscow Meson Factory by using the beams of accelerated radioactive neutron-rich nuclides to produce high yields of some new relatively long-lived isotopes of Ku and other heavy elementsZS/. References 1. Keller O.L. aadlochim. Acta. 1984. Vol. 37- P.169. 2. ZhuikoY В.1. et al. Preprint JIHR £6-88-109, Dubna, 1988. 3. Zvara I. // Inter. School-Seminar on Heavy Ion Physics. JIMR D7-87-68. Dubna, 1987. P. 145. 4. Glebov V.A. et al. Preprint JINK C6-88-201. Dubna, 1988. 5. Iljinov A.S., Iobaahev V.M. // Program of experimental investigations on the meson factory in ИШ. USSR Acad.Sci. MR. II. s 1986, P. 22. 88 SPECTRAL-LUMINESCES! PROPERTIES OF ACTHJIDBS IN ELPASOLITB STRUCTURE Yu. A. Barbanel', G. P. Chudnovsksya, R. B. Dusbin, Yu. I. Gavrish, V. V. Kolin, V. P. Kotlln, Khlopin Radium Institute, Leningrad, USSR Optical (5Г - 5f) spectra have been obtained for Hp3*, Am3* and Cm3* ions situated at sites of exact octahedral (0„) symmetry in CaoNaLaClg or OSgHaluClg elpasolite matrices, She octahedral ligand-field calcu lations were performed by the pair interaction method (Pill) f\J. Compu ter programs have been composed to obtain expressions for J~lovel splittings (for any Integer or half-integer J<8) in octahedral ligand field in terns of PIH parameters (e, ...eT) or parameters of axial field of a single ligand (b4, bg). Tables of coefficients of fractional pa rentage for the fn configuration terms of interest were used as initial data for calculations* Luminescence excited by impulse nitrogen laser (A,=337*1 nm) and self-luminescence (due to*-decay excitation) have been reoently regis tered for the 243Am- and a**0m-doped elpasolite crystals /2, 3/. Bo self- lumlnescence from 3'Np (as well as from 3*Pu) has been detected. Neptu nium photolumlnescence speotrum was measured in the range 600 - BOO nm. One of the luminescence features characteristic of the Am- and Cm- doped elpasolites appears to be dominant green glow with peak maxima at 526 and 515 nm for Am (Pig. 1) and Cm respectively. The spectral com- 460 sot m too fa> \ run *w m no Pig, I. Optical Spectra of OSglfaliafAnOclj (2.5 mol % a*3Am) Crystal в» 43 Fig. 2. Optical Spectra of Cs2NaLa(AD)Cl£ (2.5 mol % Am) Crystal in the Region 800 - 900 urn position of pnotoluminescence is almost identical to th-:t of the self- luminescence (for either of the two elements), glow intensity being an order of magnitude higher in the case of photoluminescence. Both in tensity and spectral composition of the self-luminescence remain relati vely oonstant with time for either dopant (Am or Cm), demonstrating ra diation stability of the elpasolite matrix. In the oaae of aoerioium an attempt has been made to investigate lu minescence excitation mechanisms. The excitation spectra obtained using a Xenon lamp and recorded with SSL-2 Speotrometer are shown in Fig. 1 together with the absorption and luminescence spectra. As seen in Fig. 1 Am-doped crystal luminescence (including the green glow at 526 nm) Is exoited through the whole system of purely vibronlc levels of AmClg ootahedral complex. All the major luminescence bands of the Am-doped crystal may be assigned to transitions within 5f configuration (see Pigs. 1 and 2). In particular, the assignment of two luminescence peaks in the region 300 - 900 tin (Pig. 2) to the aagnetic-dipole allowed 5 r.( D.|)—»-Г,,Г5( F2) transitions ia in a good agreement with the loca tion of vibronic Гз,Гс( во)-«—Г<)( FQ) transitions in the absorption speotrum. References 1. Dushin R. В., Shoherba b. D.//Theor. Exper. Cheat. 19S5.Vol.18. P. 450. /in Suss./ 2. Barbanel' Yu. A., Oavrlsh Yu. I., Kolin V. V., Kotlin V. P., Ohudnov- akaya a. P.//Third All-union conf. on ohemistry of trsnsplutonlum elements. Abstracts. H.: ZNIIatominforn, 1998. P. 46./in Ruse./. 3. Chudnovskaya G. ?., Barbanel* Yu. A., Oavrieh Yu. I.//Dakl. AH SSSR. 1987. I. 296. S. 1420. 90 MOSSBAUER SPECTROSCOPY AS A NUCLEAR PROBE FOR ACTINIDE CHEMISTRY Monique PAGES Institut Curie - Section de physique et Chimie Physicochimie des Elements Transuraaiens - UA 448 11, rue Pierre et Marie Curie 75231 Paris Cedex OS - France The understanding of the 5f electron structure remains a challenge for physicists and chemists working with actinide compounds. Mdssbauer spectroscopy, which is a nuclear resonance technique, has proven to be a powerful tool in the study of Sf electron structure properties in solids. Of particular interest in the case of actinide research is the fact that the method is not sensitive to impurities, does not need single crystals (powder, amorphous samples or even frozen solutions may be used) and requires relatively small amounts of material (40 to 100 mg). Most of the Mossbauer studies on actirades dealing with metals, alloys or intermetallic compounds are discussed in several extensive reviews (1,2). Conversely this presentation will be limited to the area of non conducting actinide compounds and to only Mossbauer measurements using the 60 keV radiations from 237Np excited in the «-decay of 'Am. Two hyperfine parameters, notably pertinent from the point of view of an actinide chemist, will be more specifically discussed here : - the isomer shift, which is sensitive to changes in s or p electron configurations and in Sf electron screening. Some main features which may be deduced from systematic isomer shift studies of various series of compounds (oxides, halides. oxihalides, polycarboxilates, chalcogenides. pnictides and organometallic) (3) of neptunium at different oxidation states (Ш to VII) will be presented. - the quadrupole interaction brought about by the presence of an electric field gradient which is due to a non-spherical symmetry of the electronic charge distribution around the resonant atom (unpaired 5f electrons and lattice charges). 91 Several examples will be used'to illustrate the most important information, such as the symmetry of the actinide site, the number and distribution of the ligands, the bond structure, in particular the presence of an actinyl linear O-An-O bond (which induces a strong electric field gradient), to be derived from these two Mossbauer parameters. In addition, the benefit to be gained from Mossbauer spectroscopy i:t the study of amorphous compounds, actinide glass, and frozen actinide solutions will be shown. REFERENCES B.O. Dunlap and G.M. Kalvius Handbook on the Physics and Chemistry of the Actinides Vol. 2. Ch. V, Ed. AJ. Freeman and G.H. Lander (North-Holland, Amsterdam) 1985. B.D. Dunlap Mossbauer spectroscopy applied to inorganic chemistry Vol. 2, Ed. G.J. Long, Plenum Publishing Corporation, 1987. J. Jove, A. Cousson, H. Abazli, A. Tabuteau, T. Thevenin and M. Pages Systema"5 trends in the !wNp Massbauer isomer shift, overlap of IV, V and VI neptunium oxidation states and correlation between isomer shift and crystal structure Hyperfine Interactions, 22, 1-16, 1988. 92 CHARACTERIZATION OF SELECTED SOLID-STATE ACTINIDE COMPOUNDS VIA RAMAN PHONON SPECTROSCOPY: ANOTHER SPECTRAL PROBE OF CRYSTAL STRUCTURE* W.R. Wilmarth,**' G.H. Begun," G.D. Del Cul,* R.G. Ha ire," and J.R. Peterson1 'Department of Chemistry, university of Tennessee, Knoxville, ТЫ Э7996-16О0 USA transuranium Research Laboratory (Chemistry Division), Oak Ridge National Laboratory, P О Box 2008, Oak Ridge, TH 37831-6375 USA Although Raman phonon spectroscopy has been used to characterize many lanthanide sesquioxides, oxyhalides, and trihalides in the solid state, its use to characterize similar actinide compounds has been limited and focussed only on the lighter members (Th - Hp) of the series. We propose that from an analysis of the Raman phanon spectrum of an actinide compound, we can often identify the crystal structure exhibited by that actinide compound. Raman phonon spectra arise from excitations of the quantized vibrations (or motions) of the individual atoms in the unit cells of the crystalline compound. Because each crystal structure has a unique unit cell, the Raman phonon spectra of crystalline materials with a particular crystal structure exhibit similar Raman band patterns which are shifted in frequency (energy) according to the masses of the atoms undergoing vibration. In the figure are displayed the Raman phonon spectra of A1C13, YC13, and cfBrj, all of which exhibit the A1C1,- type monoclinic crystal structure. The relative intensities and number of Raman- active bands (two sets of a stronger peak sandwiched between two weaker peaks) that are observed in these room-temperature spectra provide a clear, easily recognizable fingerprint for this particular monoclinic crystal structure. Note that the frequencies of the Raman bands are shifted to lower wavenumbers (energies) with an increase in formula mass. Use of Raman phonon spectroscopy as a probe of crystal structure frequently offers advantages over the usual angle- dispersive X-ray diffraction method in investigations of the heavy actinides. The high specific radioactivity of these elements can cause rapid and extensive damage to the long-range order in the 100 200 900 solid, with a concomit? decrease in 1 :t A WAVENUMBER (cm*) quality of the diffraction patterns which can be obtained. With some aetinides the ^""^"P*"*"!* Raman phonon spectra of monoclinic A1C13, YC13, emitted radiation is so intense that it and CfBr, darkens severely the X-ray film or 93 saturates the X-ray detector such that a useful diffraction pattern is not readily obtained. An important aspect of Hainan phonon spectroscopy Is that a spectrum can be obtained in a relatively short time (10 - 3D min) as compared to the usual X-ray exposure tines for snail, actiniae samples. As such Raman data can be taken immediately following an annealing treatment of the actinide sample, before -дпу significant self-irradiation damage occurs. Raman spectra are obtained in our laboratory with a Ramanor HG-2S spectrophotometer (Jobin Yvon Instruments SA), equipped with a double monochromator utilizing curved holographic gratings* a cooled photomultiplier detector, and pulse counting electronics. A signal averager is used to accumulate spectra from multiple scans. An Ar-ion or a Kr-ion laser is used as the excitation source and the Raman scattered light is collected at 90* froic the laser excitation beam. The Raman phonon spectra of a number of crystalline actinide oxides, halides, and oxyhalides have been obtained in our laboratory. Tentat./e symmetry assignments have been made, where possible, for the observed Raman- active bands by analogy to the assignments made for isostructural compounds. Examination and interpretation of -bese spectra have demonstrated that many crystal structure transformations can be monitored by Raman phonon spectroscopy. Examples from our growing data base of Raman phonon spectra will be shown, limitations of this spectral probe of structure will be mentioned, and useful applications of this technique to the study of actinide compounds under varying conditions of pressure and temperature will be discussed. «Research sponsored by the Division of Chemical sciences, office of Basic Energy Sciences, U.S. Department of Energy under-grant DE-FGO5-88ER13865 to the University of Tennessee, Xnoxville and contract DE-ACQ5-84ER214OO with Martin Marietta Energy Systems, Inc. 'Present address: Actinide Technology Division, Savannah River Laboratory, Aiken, SC 29808-0001 USA 94 IASER EXCITED FLUORESCENCE SPECTROSCOPY OF PROBE IONS FOR THE CHARACTERIZATION OF CRYSTAL SITE SYMMETRIES IN LANTHANIDE AND ACTINIDE ««POUNDS* I 2-27 G. И. Murray,* R. V Sarrio," o. L. Keller,b and J. R. Peterson'-1* J "Department of Chemistry, university of Tennessee, Knoxville, ТЫ 37996-1600 USA 'Transuranium Research '.Laboratory (Chemistry Division), Oak Ridge National Laboratory, P О Box 2008, Oak Ridge, TN 37831-6375 USA Nunerous methods have been employed to elucidate structural information concerning actinide compounds. Although single crystal X-ray determinations give very detailed structural information, it is often impossible to prepare an actinide sample suitable for this analysis due to the high specific radioactivity and/or a Halted quantity of material. These complications call for an alternate method for acquiring structural information. One such method is laser excited fluorescence spectroscopy. Previous studies of the fluorescence of inorganic rare earth compounds [1], as well as recent studies of the fluorescence spectra of rare earth chelates [2], have demonstrated the utility of fluorescence spectra in the determination of the site symmetries of the tripositive rare earth ions in crystalline compounds. The crystal field splittings of the fluorescence manifolds can often be interpreted as Indicating a specific point group for the site symmetry around the rare earth ion. This interpretation is performed by comparison of the observed fluorescence manifold multiplet structure with the pattern expected from a group theoretical analysis of a candidate point group, when this information is considered in conjunction with the analysis of a Raman phonon spectrum obtained from the same sample, considerable insight is gained about the stru ture of the crystalline compound. The methods of laser excited fluorescence and Raman phonon spectroscopy compliment each other well and can be performed using the same instrumentation. Although the site symmetry can be inferred directly from the crystal field splittings of the f-f fluorescence transitions exhibited by Ln(III) and /in(III) ions, especially Eu(III) and Am(III), some of the manifolds are quite complex and require extensive deconvolution. This situation could be avoided by the use of a spectroscopic probe ion, such as Eu(XXI), whose manifolds are relatively uncomplicated and simple to interpret, in order to evaluate the possibility of using dopant ions as spectral probes of crystal structure, it is first necessary to determine if the probe ion exhibits fluorescence characteristic of its host compound's site symmetry. Next, it is necessary to determine the proper mole ratio of probe ion to analyte to insure adequate signal while maintaining sufficient dilution for the probe ion to reflect accurately the geometry of its host's crystal. Once these conditions have been examined using fluorescence spectroscopy and compared with the results of x-ray diffraction analysis, it should be .possible to extend this method to deal with actinide samples, such as Es(III) and Ea(II), that are nor amenable to normal X-ray methods. In order to discern the feasibility of the approach outlined above, many in(IH) and some An(III) chelate compounds, employing the ligand 2,6- pyridinedicarboxylie acid, have been synthesized and examined by x-ray 95 crystallography and laser excited fluorescence spectroscopy. This ligand was chosen because it farms strong complexes with lanthanides and actinides, produces transparent or translucent compounds/ and transfers some of the radiant energy it absorbs to the chelated lanthanide or actiniae ions resulting in the observed metal ion fluorescence. This energy transfer mechanism facilitates fluorescence of the lanthanide or actinide ions when a source for resonance excitation is unavailable. Studies were performed on the above compounds to examine the effects of dilution of the probe ion on its fluorescence spectrum. The results of these studies determined the usefulness of this technique in characterizing actinide compounds. The successes and limitations of this spectral probe of crystal structure will be discussed. References 1. Serra, o. A.; Thompson, L. С inorg. chem. 1976, is, 504. 2. Hurray, G. M.; Pesterfield, L, L.; Stump, N. A.; Schweitzer, G. K. Submitted for publication in inorg. слеш. •Research sponsored by the Division of Chemical Sciences, Office of Basic Energy Sciences, u.S. Department of Energy under grant DE-FG05-88ZR13865 to the University of Tennessee, Knoxville and contract DE-AC05- 84ER21400 with Martin Marietta Energy Systems, inc. HIGH RESOLUTION NEUTRON SPECTROSCOPY OF CRYSTAL FIELD EXCITATIONS IN NpOj 2-2B J.M. Fournier1, A. Blaise1, J. Larroque2, G. Amoretti5, R. Caduffo*, H. Hutching;', R. Osborn*, A. Taylor* 'SPh/MDM, Departement de Recherche Fondamentale, Centre d'Etudes Nucleaires de Grenoble, 85X, F-38041 Grenoble cedex, France MRDI/DHECN/OECPu, Centre d'Etudes Nucleatres de Cadarache, BP 1, F-13108 St Paul lez Ourance, France 'Dipartimento d1 F1s1ca dell'Universita d1 Parma, Vlale delle Sctenze, 1-43100 Parma, Italy 'Oipartimento dl Scienze dei Material! e della Terra, Sezione Flslca, Universita di Ancona, via Brecce Blanche, 1-60131 Ancona, Italy 'Materials Physics and Metallurgy Division, Harwell Laboratory, Didcot 0X11 ORA, UK 'Neutron Science Division, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OQX 0X11, UK Following our successfull study on U02 [1], we have performed high resolution neutron spec troscopy measurements on Np02 using the high energy transfer spectrometer НЕТ at the pulsed neutron source ISIS of the Rutherford Appleton Laboratory, The sample was prepared at the Centre d'Etudes Nucleaires de Cadarache. It consists of 3zg of Np02 powder doubly encapsulated in a special Al holder. A sample of Th02 encapsulated in an identical container was also prepared, at RAL, to allow detailed phonon density of states substractions. Earlier experiments carried out at IPNS, Argonne National Laboratory, have not revealed any sharp peak up to energy transfers of about 250meV [2]. However, because of the greater flux of ISIS we used a sample having a mass ten times smaller. This considerably reduces the multiple phonon scattering as well as the self heating problems inerant with the "7Np «-activity. The measured scattering function S(q>,u) for Np02 and Th02 at 5К is shown in Fig.l for low Q with 120 meV incident energy. No s':.-p transition is observed but magnetic scattering is clearly visible around 60meV. Scans with higher Incident energy did not detect any transition up to 350mev. Fig.2 shows a difference spectra (NpOa-Th02) at 5K, low Q with 180meV Incident energy. A broad peak, centered at - 60meV having ~ 20moV FHHN 1s definitively resolved toge ther with quasi elastic scattering below 20meV. Crystal-field calculations with parameters z determined for U02 [1] predict a strong rj > - rj" transition at 55meV and a second much weaker rj" - Г, transition at 260meV. He believe to have observed the r,!> - rj11 transition while the rj*' - r6 one was not detected. The broadening of the transition could be due to interaction with optical phonons at SSmeV. He don't have yet an explanation for the quasi elastic scattering. The possibility that it originates from transitions within the ground multlplet should oe examined. 7.3an.1607 91 1000 i • i —i—i—i—i—1—i—•—i—1— Т=5К ЕМКОМУ - 800 1 • Np0 » 2 i , о ThOj э 600 - »\ - 400 Г • гоо » 0 • —1^, . 1,1,1,1,' -40 -20 0 20 40 60 ВО 100 Energy TransfertrnsV) Figure 1 - Low Q neutron Inelastic scattering cross section of Np02 and ThOj at T • 5К, observed with an Incident energy of I20meV. 250 T=5K E.=180ir««V ' гоо NpO2-Th02 150 3 »100 in V. 9 щ -40 -20 0 20 40 60 80 100 120 140 Enerqv~Trpr.eF«rtm«V) Flqure г - Low I) difference spectra (Np02 - Th02) at Т • SK, Incident energy I80imV. References 1 R. Osborn et a).//). Phys. С 21, L931 (198S) ; tS. Anoretti et al., RAL Report 38-096 and to be published 2 S. Kuri et al.//J. Appl. Phys. S3, 3598 (1988) 237 MuJdBAUBR SPECTROSCOPY OP Np IB SObID SOLUTIONS 2-29 uH ACTINIDE DIOXIDES V.M.Filin, V.P.Gorbunov, S.A.Ulanov All-Uhion Research Institute of Inorganic Ifeterlals* Moscow, USSR Emission mbasbauer (nuclear gamma-resonance) spectra of 'Ир resulting from the alpha-decay of 4 Am. in the solid solutions prepared by the precipitation from the LiP^faP eutectica melts at fluorine-oxygen exchange were first investigated in the temperature range from 77 to 296 K, The NGR spectra were measured in the samples with different contents of AmOg and at various exposure time after the preparation* The resonant absorbers are NpOg and NpAl** Prom the spectra the author determined the distribution of radiogenic neptunium in the valent and structure states in the lattices of solid solutions and the parameters of the superfine interaction of "wp in the these states. Using the results of the present and recently published work the parameters of the superfine interaction of ""up were systematized in the range of the aotinide dioxides from ThO. to AmO_. It is shown that the experimentally observed dependences of the radiogenic neptunium in the valent states on the stoichiometry of dioxides and their impurity content as well as the dependence of the parameters of the quadrupole interaction on the temperature in the range 77-296 К were related to a change in the solid solution electron subsystem state produced by the these effects. Ihe possibility of managing the form of the emission mossbauer spectra of -*'Np is stated in dioxides by the directed change of the matrix stoichiometry or by its irradiation by the visible light* At temperatures from 77 to 230 К the authors measured for the 237 first time the NOR absorption spectra of ^*Np in the solid solut ion WpOg-ThO- with various concentrations of the neptunium dioxide. An increase of the absorption line width (approximatelly by a factor of 4) with a decrease in the NpOg contents ('-to 10 mol*#) was explained by the influence of the fast electron exchange between Np*+ and Kp5+ states observed in the solid solution HpOg-TnO- at low concentrations of neptunium dioxide* 99 SPECTROSCOPIC STUDY AND CRYSTAL FIELD ANALYSIS OF PU,+ IN THE THORITE ThSiO, MATBIXI 2-jo J.C. Krupa, M.P. Lahalle, W.T. Carnall* and G.L. Goodman* Institut de Physique Nucleaire, B.P. №1, 91406 Orsay Cedex (France) * Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA The electronic structure of tetravalent plutonium (5f*) diluted in the tetragonal host ThSi04, has been investigated using optical spectroscopy. Single crystals of ThSK>4 doped with approximatively 0.1 % in weight of 2,<2Pu were grown from an equimolar mixture of ThOj and S1O2, by the flux method using L12M0O4/M0O3 as solvent. The well-shaped crystals, of the order of 1x0.3x0.3 mm3 were set out in close order and glued on a silica plate with the optical axis parallel to the slit of the monochromator. In that way, a ant ir polarized absorption spectra were recorded at 4.2 К in the visible and infrared region between 300 nm and 2000 nm. 4+ In the tetragonal ThSi04 (space group I4i/amd) the Tb ion is sur rounded by eight oxygen atoms forming a dodecahedron with two sets of Th-O distances. This oxygen arrangement provides a D2d site symmetry for the metallic ion Th4+ (or Pu4+ substitued for) and the crystal-field inter action removes to a certain degree the degeneracy of the free-ion levels. For an even number of f electrons the crystal-field eigenstates are transformed into four singlet, Г] through Г4, and one doubly degenerate, Г5, represen- tatic n Then, according to the selection rules for a D2d symmetry and the number of absorption bands recorded for well-isolated multiplets, the ground state was assigned as Г3 and the recorded electric dipole transitions as: Г3 —»Г2 forE\\? (л- polarization) Гз -* Г5 {orE JL с (a polarization) These experimentally measured energies were compared to calculated energies. The calculation is based on a parametric approach with a sep aration of the variables which characterize the potential acting on the f electrons. Following this procedure, the angular part of the interaction is totally evaluated from geometrical considerations while the radial integrals depending upon the unknown potential are treated as parameters. The calculated energies were obtained by a simultaneous diagonaliza- tion of the free ion HF/, and crystal field H-CF 1 hamiltoaians. HV/ take3 into account the electrostatic ans spin-orbit interactions parametrized re spectively by the Slater integrals F* (k=0,2,4,6) and the spin-orbit coupling constant с. Hf/ includes as well second order interactions described by the configuration interaction parameters a,/3,7, the spin-spin and spin-other orbit interaction parameters M* (k=0,2,4), the electrostatic spin-orbit and higher configuration interaction parameters Pfc (k=:2,4,6) and at last the three body configuration interaction parameters T* (k=2,3,4,6,7,8). The crystal field hamiltonian HCF in a Did symmetry can be written as: 100 HCF = Bid + B$C* + ВЦС* + Clt) + Bid + BJ(CJ + C°<) where the B£ are the crystal-field parameters. The obtained free-ion parameter values will be discussed in term of comparison with on the one hand, the predictive model [1] F* and ? values, based on HFR calculation and on the other hand, the values determined for lighter actinides Pa4+, U',+ and Np4+ where the f electrons are known to be more delocalized. The crystal-field parameters will be also compared and discussed as a function of the radius of the actinide ions diluted in a same host. Pu4+ :TkSiOi polarized absorption spectra. The absorption of Pu<+ in DCIO4 id reported in grey for ПОЗ ТОЮ 6M0 СОЯ MOO 9000 4900 comparison 1 W. T. Cornell and ИМ. Grosswhite "Optical Spectra of Actinide Ions in Compounds and Solutions" ANL Report- ANL J4-90 (1985) 101 DETERMINATION OF ISOTOPIC RATIOS OF PLUTONIUM I 2-31 j AND CURIUM BY INTERNAL CONVERSION ELECTRON SPECTROMETRY' —I Y.SHIOKAHA, K.SUZUKI, S.SUZUKI*, M.YAGI Institute for Materials Research, Tohoku University, Sendai 980, Japan *Japan Radioisotope Association Takizawa Laboratory, Takizawa, Iwate 020-01, Japan In generally, Identification and assay of actinide nuclides have been carried out extensively by alpha and ganuaa-ray spectro- meties. By the former method, however, it is very difficult to determine isotopic ratios of 240Pu to 239Pu and 244Cnt to 243Cm, because of close proximity of alpha ray energies. By the later method, on the other hand, it is very hard to determine the above ratios because of their extremely low photon Intensities. On the basis of the fact that alpha decays in actinide nuclides are often followed by highly converted internal transition, in the present study, a new internal conversion electron{ICE) spectro meter with a windowless Si(Li) detector was constructed to deter mine effectively the above two isotopic ratios. The ICE spectrometer In order to avoid the energy loss of Incident electrons, it is required that the detector and a radioactive source are placed in a vacuum chamber. Figure 1 shows a schematic view of the ICE spectrometer. The energy resolution was found to be 0.49 keV in FWHM for 42 keV electrons. TW-150 1.31 СИ) 4«t*otor Ф г.*1Л1пв feedthfcuflh 2.oryostet I I 10.taafc *•!*• 3, d««tr Ь " И I!. l&DtntlM OMJ» 4. Fig. 1 Sohematio view of the ICE spectrometer 102 The isotonic ratios off 240Pu to 239Pu and 244Cm to 243Cm Since we had no adequate reference sources» the correlation between the isotopic ratios of °Pu to 23*Pu and the observed 2< 239 intensity ratios of *°Pu 45-LtlI lines to Pu 52-Lj IX, was examined, and the results obtained are shown in Fig. 2. it is found that the isotopic ratio can be determined easily by ICE spectrometry. The radioactivities of 243Cm and 244Cm were determined by gamma-ray and ICE spectrometries, respectively, and the results obtained are tabulated in Table 1, together with the total radio activities measured by alpha-ray spectrometry. It was indicated that two suns of radioactivities due to two nuclides are in agreement with those obtained by alpha-ray spectrometry. ID7! Isotopic ratio of 240pu/239pu Fig. 2- Relationship between the peak intensity retia and the isotopic ratio Determination of 243Cm and 24 103 LUMINESCENT PROPERTIES OF THE RELEVANT LANTANIDE-BlOLOfilCAL MOLECULE! 2_32 SYSTEMS ' M, ELBANOVSKI , DEPARTMENT OF RARE EARTHS, FACULTY OF CHEMISTRY,, A.MICKIEWICZ UNIVERSITY, POZNAN, POLAND MANY BIOLOGICAL MOLECULES (E.G. PROTEINS, NUCLEO.IDES) REQUIRE METAL IONS FOR THEIR ACTIVITY OR CONTAIN BOUND METAL IONS IN THEIR NATIVE STATES, SOME OF THESE METALS .(CU,FE,MO) EXHIBIT USEFUL SPECTROSCOPIC OR MAGNETIC PROBE PROPERTIES, WHILE OTHERS (ZN,MG,CA) DO NOT. WHEN THE NATIVE METAL IONS DO NOT EXHIBIT THESE PROPERTIES, IT IS POSSIBLE TO SUBSTITUTE AN ION HAVING USEFUL FEATURES. THE REPLACEMENT OF CA ION BY LANTHANIDE (E.G. EU ION) CAN BE THE MOST INTERESTING EXAMPLE, THE INAPPLICABILITY OF SPECTROSCOPIC TECHNIBUES TO CA ION CAN 3E PARTLY OVERCOME BY USE OF LANTHANIDE ION AS THE PROBE, EU ION RESEMBLES CA ION IN SIZE AND IS IN PREFERENCE FOR OXYGEN DONORS IN COMPLEX FORMATION. LANTHANIDE ION COMPETES WITH CA ION IN BINDING SITES IN MANY PROTEINS AND CAN ACTIVATE A BIOLOGICAL SYSTEM TO ITS FUNCTION IN THE ABSENCE OF CA ION. THE MAIN SCIENTIFIC PROBLEMS CONCERN RESEARCH OF THE BIO-CHEMICAL-PHYSICAL MODEL WHICH CAN CORRESPOND TO THE LIVING, NATIVE BIOLOGICAL SYSTEM. THE PRO PERTIES - IN THIS DOMAIN THE STUDY OF THE MODEL UNITS BY THE CHEMILUMINESCENT METHOD IS THE MOST INTERESTING, CHEMILUMINESCENCE OF THE LANTHANIDE ION (ЕИ<Ю/ЕИ(ЦП>, RELEVANT BIOLOGICAL MOLECULE (NUCLEOTIDE OR DNA) AND OXYDI- ZIN6 AGENT (H2O2) SYSTEM ARE INVESTIGATED.THIS SYSTEM IS WORTH A WIDE DIS CUSSION DEALING WITH! -.CHEMILUMINESCENCE AS A PHENOMENON AND SPECTROSCOPIC METHOD - RANGE OF USING CHEMILUMINESCENCE IN VARIOUS REGIONS OF CHEMISTRY AND BIO LOGY - WITH A METAL (LANTHANIDE) ION AS A SPECTROSCOPIC PROBE - COMPARATIVE INVESTIGATION OF FLUORESCENCE SPECTRA WITH REGARD TO EU BIOLOGICAL MOLECULES SYSTEM, IN CONNECTION WITH ENERGY TRANSFER PRO CESS- OCCURRING IN THE BIOLOGICAL SYSTEMS - PERSPECTIVE TREATMENT OF CHEMILUMINESCENT METHOD IN THE RANGE OF ALIVE, BIOLOGICAL SYSTEMS. THERMODYNAMIC PROPERTIES CHEMICAL BEHAVIOR OF ACTIIJIDES DURING CHERNOBYL ACCIDBHT 3-1 I.L.Khodakovaky, M.V.Mironenleo. Vernadsky Institute of Geo chemist ryana* Analytical Chemistry of the Academy of Sciences of the USSR.Moscow, USSR The aim of this study is to analyse tbs main physical and chemical pro cesses controlling the chemical behaviour of the actiniues during the Cherno byl accident. The study is based on measurement data for dynamics of tempe rature and estimations of the rate of air flow through the reacror bottom* Thermodynamic and kinetic data for different chemical reaotiona were used for simulating of the intersetin processes between filtrating gas flows and construction and nuclear materials* 1. Basing on the kinetic data for graphite combusting it was demonstrated that processes of air oxidation should control redox potential. The latter was detbrminad by the degree of graphic combusting in different areas of the destroyed reactor. The evaluations demonstrate that the share of the combusted graphite is abo>«t 20%. Simultaneously the thermodynamic calcula tions and evaluations of chemical reactions velocities have shown that the processes of actinides cerbldization were the most possible. Those actinides were initialy presented in the reactor in the form of oxides. 2. We used the Gibbs Free Energy minimization method to simulate the in teraction processes between filtrating gas flaws and construction and nucler materials. This simulation is based on computer calculations cf the compo- si tion of amiticomponent heterogeneous systems. We used our own thermodyaa- reii data bank. The behavior of uranium and plutonium was considered in detail. It was shown that the factor of graphite combusting in different local zones of the reactor controlled the fugacities of actinides in the gas phase аз well as their chemical forms in aerosoles. The uranium fugacity increased under oxidizing conditions, the plutonium fugacity - under reducing conditions* 3. Chemical forms of actinides in releasing gas were estimated* It was shown that along with mechanical release of "hot" par tides condensation and adsorption on the .soot from the gas phase took place* 106 DEFECT STRUCTURES IH ACTIHIDE OXIDES СОЖЕЬАТЕО WITH ВПЫС, I _ ' THBMIQPHlSICAL ADD ТННШОПНШПС PROPERTIES I ll.Beauvy. Counissarlat a. l'vnergle atomlque IRDI/DMBCN/DECPU/SPU/SEFCA CEH/Cadarashe 13108 Saint Foul Loz Durance Cedex, Trance The ionic structure model of defects in (и,Ри)02_х was proposed by Markln and Maclver in 1965 /!/• The hypoetoichiametry in these fluorlte crystals is assumed by the oxygen vacancies, and the electrical neutrality is balanced exclusively by the variations in the valence of the plutonium ions: 2Pu**--^ —»2Pu^+ ~ 2e~. This model was deduced from thermodynamic measurements on limited compositions of compounds. Using the same experimental technique, Blackburn and Johnson /2/ hare confirmed the ionic state of the actinldas in (U.PulOg . and two types of clusters were proposed to explain the variat ions of the nuclear fuel properties: /2PU - Vo/ by Schmitz and Uarajofaky ClJ, or /2Pu3+ - 2PU4* - Vo - 402~/ by Kaneo and Manes-Pozzi Д7. Unfortunatly, the thermophysical and transport properties on mixed oxide samples covering a wide range of compositions oannot be explained by the clusters built on the Harkin and Maclver rules the results of measurements of the unit cell parameters, the thermal and the electrical properties, are reported to argue this discrepancy. The main concousiona are to reject the limited biunivoque single correlat ion between Pu , x and у in (В, Рп.)Ог_х which la the source of the de fect structure used up to now for this actinide oompoimd, and consequently the hypotheses of the "Ideal" solid solution between UOp and PuOg, even for у & 0,3. The comparison with the other fluorite structured compounds doped with low valence ions brings some arguments for a complexe defect structure in the actinide mixed oxides. The point-defect model proposed by Unwick P3 is dis cussed for uranium oxide with low dopant concentrations of transuranium ac tinide. The results of theoretical calculations published by Catlow /67 have been included In this dlaousslon. The experimental investigations by spectroscopy and bulk propertirn mea surements have been done on (U,Pu)0g_x and (U,Ce)02_I: results on optioal transmission, electrical resistivity and magnetic transitions are reported. These remits associated with the thermophysical properties of the mixed oxides suggest a new thermodynamic model of defect structure for С).Л'(1г.1' Reference 1. llarkin Т., Haclver E. Luton turn 1965. London: Chapman and Ball, 1967.P.845. 2. Blaokburn P., Johnson E.C. // ALBA Proc. ot symp. on "Thermodynamics of nuclear material". Vienna, 1974. Vol. 1. P. 17. S.Schmitz P., Harajofsky A. // Ibid. 1974. Vol. 2. P. 457. 4. Наг.э& Ь., Иапев-Рогг1 Р. Plutonium and other Aotinides / Eds. Blank and Lindner. north-Holland Pub. Co., 1976. P. 145. 5. Howiek A. S., Da Yu Vang, Park D. S., Griffith J. // Bast Ion Transport in Solids / Bds. P.Vashlshta, J.H.Hundy, G.K.Shenoy. north-Holland, 1979. P. 673. 6. Catlow C. // Proc. R. Soc. London A. 1977. Vol. 353. P- 533. 107 SEHIEUFIRICAb HEfflODS FOR EVAMIATIKG MOLECULAR AM) ENERGY PARAMETERS OF SOME АСТШГОВ COMPLEXES 3-3 8, V. Konarcv, K. V. Perepech, L. В. Shpunt. Khlopin Radium Ins tit ate, Leningrad, USSR The system consisting of a cation and a ligand is described within the scope of a simple LCAO ЫО method by the following secular equations The solution of this equation gives a system of energy levels of the cation-ligand complex under consideration. An increase of the cLe-&£ difference cauees a decrease of the covalent contribution into the total energy of the system. The consequence of this decrease is an electrosta tic character of the bond in hydrates of some metals. Applicability of the electrostatic model baa been checked for hydrates of cations of the first group of the Periodic system as an «cample» Table 1 Hydration Energy of Cations of the 1-st Group Cation Radius« , Experimental Calculated A hydration hydration energy, energy, kJ/mol kJ/mol li+ 0.60 519 536 Ba+ 0.96 406 384 K+ 1.33 322 308 Ro+ 1.46 293 2S4 Cs+ 1.65 264 255 Die experimental data presented in Table 1 , «ere taken from /]/. The elnctrostatic model enables to evaluate also some molecular characteristics of complex compounds. A dependence of the potential energy on the coordinates was used for calculating the force constants of the bonds of a number of oomplex compounds. 108 Table 2 Experimental and Calculated values of the valency Oscillations Frequencies Compound Symmetry type Sc^evlm» cm" Calcul. cm M pt(HK ) ci D 322,326 3 2 2 2h 338 uo ci D 2 g 2h 417 404 OO (KO ) D 2 3 2 2h 370 345 lte /U0 Cl /' D 2 2 4 4h 240-230 236 PU/HO / D 3 4 4h 420 426 •Me - cation of first group metal* She experimental data were taken from /2\3.47- Ihe analysis of the experimental data for MeOg lone of uranides cannot be explained by the simple electrostatic model. Application of the simple Ы.А0 MO method and spectral data enabled to evaluate the charge on the metal atom in the МеО|г grouping. Die obtained estimates for the charge and the value of interatomic distances ware used in calcu lation of the relative extraction oonstante of uranides. ?he Caloulatec dependence of the logarithm of the relation of the complexing constants is a linear function of the difference of the ehaigeB on metal atoms, and coincides with the experimental data of Fi] within the limits of experimental error* References 1. Cotton P. A*, Wilkinson G. Advanced inorganic chemistxy. A comprehensive text. 11. Y.,1962. 2. Uodern coordination chemistry. Principles and net hods /Ed Lewis J. and Wilkins H. G. I960. 3. Bozen А. H., Danidov 0. A., Hlkolotova Z. I.//Zh. Piz. Khim. 1972. T. 46, И 3. 8. 566. 4. Suglobov D, ц. Diss. For soi. degree of doctor of Chem. Sci., 1970 Leningrad. Radium Institute, (ia Russian). 5. Zemlyamikain V. I*, Savoskina в. Т., Fushlenkov H. F.//Radiokhimiya. 1963. T. 5, H 6. S. 674-681. 109 EVALUATION О? THE THERMODYHAMIC PROPERTIES OP ACTINIDES AMD Г>4 LANTHANIDBS LIQUID ALLOYS I — V.A.Lebedev, Urals Polytecbnical Institute, Sverdlovsk, USSR In 1976 the data of 80 papers devoted to thermodynamic properties of actinides and lantbanidea liquid alloys have been systematized by the aut hor. It was found that partial enthalpies o.f solid actinidea and lanthanides -1 in liquid metals (feg) with atomic radii r2URf *«* mol ) and in intermetallic compounds which are in equilibrium with saturated solutions (д!?,1ь7 mol ) are directly proportional to electronegativity difference of components. _Й-Я = а + b л X „..,„.. a + Ь'лХ1 Me2 r2,nm - a -b I -a 1 -b Zn 149.0 468.6 8.8 478.2 0.133 Al 174.5 190.8 128.9 178.2 0.143 fla 89.1 442.S 8.3 478.2 0.122 ca.in, -1.7 440.6 -141.4 544.3 0.145;0.150; Sn,Sb 0.НПО,145 Tl.Pb -110.9 436.4 -218.0 469.0 0.17П0.175 Bi - 73.2 432.6 -112.1 404.5 0.156 The enthalpies of actinides and lanthanides in all liquid metals (except Al),in intermetallic compounds which are in equilibrium with saturated solu tions (except Al and Zn compounds) may be evaluated by to the equations: 1 дН,Ы mol" = - 567.4 +3946r2 - 439.Зд SB + 23.8, 1 AHtlcJ mol"* *= - 569.0 +4531r2 - 468.6A Э£ + 21.6- Check-up of. the model in 1960 year on 201 values дИ and 120 values лЙ show her correot,if take et^a 1.2 ,«^=1,3 * rSn=0.151nm , rBi=0.l65nm. In the present work on single data of the thermodynamic properties fcp-Cd and Ра-Bi alloys values 36M «1.2 and Зе^, =1.2 are established. According to the model being developed the valuea of дН and дН are equal in liquid alloys of U and Lu (a£=1.4); Th and So,Er,Tm,Yb(ae=1.3)jPu,Np,Fa and Y,Sm,Ev,GdfTb,0y(3e=1.2); La,C.e,Pr,Nd<3e «1.1). The mean values of partial entropy of actinides and lanthanides (A) in intermetallic compounds which are in equilibrium with saturated solutions C-A3,J mol"1K*"1> are equal for: A3..., -191.6 +12.6; АБ.-90.4 +.6.3;ЛЕ„-7-» .1 z. 7»5iAB2-56.i +. 8.4j AB - 23.8 + 5.a". The spectrum of the values of excess partial entropy of actinidcr. and lanthanidee in liquid solutions ( - A"S*J mol К )approaches to the spect rum of the values -*3 : 90,4 + 10.5 to Zn,Cdj 75.7 + 4-2 to Al; 22.3 ±4.2 to Bi etc. It shows that in liquid solutions there are microgroups,similar Intermetallic compounds AB.(2n,Cd solutions); AB., AB2( Al.Ga solutions); AB ItO STATIC ULTRA HIGH PRESSURE DIAMOND ANVIL STUDIES ON THORIUM AND URANIUM J. AheHa ana G. S. Smith Lawrence Livermore National Laboratory. Livermore, USA With the advances made in damond-anvil-cell technology, it Is now possible to generate pressures In the multi-megabar (>1QO GPa) range. However. In order to achieve such high pressures, diamond-anvils are designed to have single bevel or double bevel angles, with a central flat ol 25-100 urn in diameter for the sample (Moss et ai. 1966). Because of the prevailing поп. hydrostatic!!/ et these pressures (gradient ts 5-10 GPa over 75 urn, Vera el. al. (1986), depending upon the type of pressure medium used], conventional X-ray sources are not suited lo obtain accurate data. With conventional X-ray sources, the X-ray spot cannot be collimated to less than 50 цт, also by collimating the X-ray beam to smaller size the net intensity will be so low it is not possible to get X-ray data within a reasonable time. Thus, ft is necessary to use X-rays from a synchrotron source and solid-state detectors (energy dispersive X-ray diffraction EDX) to collect data. Synchrotron sources are - eight orders of magnitude more briliianl than a rotating anode source, and the highly coherent X-ray beam can be collimated down to 5-10 urn. The combination of high beam intensity and excellent colDmation are essential In eliminating (he pressure gradient problem (over 10 urn the gradient is < 0.5 GPa) and In minimizing the lime required for data collection {10-30 minutes at each pressure). We used both a rotating anode X-ray generator with film and a synchrotron X-ray radiation source with solid state detector to collect data for some acllnide metals up to 100 GPa (one megabar) pressure. in the actinide series (actinium Ihrough lawrenclum) the 5F shell is gradually filled and according to Johansson and Rosengren (1375), the Sf wave function Is fairly localized. Kmetko end Hill (1970) have shown, from energy-band calculations on acitnldes, that the earlier actinide metals (Pa - Pu) give good evidence for an itinerant character of the Sf electron. On the other hand, the 5f electrons in the heavy actinides (Am and above) are localized and their properties resemble those of the rare-?arth elements which have localized 41 electrons. So we have undertaken a systematic high pressure study of (he acttnWes and lanfhanides. The high pressure slructural changes and equation-of-siate (EOS) for Th and U up to 100 GPa. along with some preliminary data for U at elevated temperatures {- 45oDC) and - 15.0 SPa pressure will be presented. In thorium no structural changes were observed up to 100 GPa. However, a slope change in the P-V curve was observed between 20-30 GPa. This slope change was attributed to fue s-d transfer, which is in agreement wilh the conclusion arrived al by Skriver and Jan (1980) «om their seif- consistem energy-band calculations on thorium as a function of pressure up to 40 GPa. There is a reasonable agreement between our P-V data and the experimentally measured data of Bellusl et. al. (1981) and Benjamin et. al. (1981) for pressures up to 25.0 and 67.0 GPa respectively. 111 In uranium at about 71.0 GPa we observed new reflectionsan d Intensity changes in the diffraction patient compared to.lne diffraction patterns at and below SO.O GPa. A careful examination of the pattern suggests that it has reflections from both uranium and possibly a new phase. Unequivocal confirmation of this possible structural change Is stiH needed. From our studies on other actirtfdes we predict that the U high pressure phase could have a hexagonel-cluse- packed structure. The room temperature volume compression curve calculated from shock compression dala falls below both our data and those of Mere and Moussln 0979). The isothermal bulk modulus at zero pressure B0 and its pressure derivative B'0 from our data are however in gcod agreement with the ultrasonic values of Simmons and Wang (1971). References, Beiiusi, G.. benedict, U. and Hotzapfei. W. В., 19Е1. Less. Comm. Metals. Z&147. Benjamin, T. M., Zou, G„ Мао, H. K. and Bell, P. M., 1981, Carnegie Insftution Geophysical Laboratory Year Book, flu, 280. Johansson, B. and Rosengren, A., 1975. Physical Review, B.11, 2836. Kmeiko, B. and Hill, H. H., 1970, Proc. of Fourth In). Conf. on plutonlum and other actinides, Edt. A. M. Miner. АННЕ. *ew York. Merx. н. and Moussin. C, 1979, In High Pressure Science and Technology Ш-1. P- 204, Edts. B. Vodar and Ph. Martettu, Pergamon Press. Moss. W. C, Hafiqulst. J. O., Retehlin, a, Goettel. K. A. and Martin, s.. 1986. AppL Phys. Lett. 4Д, 1258. Skriver, H. L. and Jan, J. P., 1980, Phys. Rev. B, 21, 1489. Vohra. Y. K„ Brister, K. E.. Weir. 8. Т., Ductos, S. J. and Ruoff, A. L. 1986, Science, 231, 11Э6. Work performed under *.$ auspices cf the U.S. Department of Energy by the Lawrence Livermorg National laboratory under contract number W-7405-ENG-48. 112 (y=0.044, ana 0.142) 3-6 FROM ЭО0 TO 1500 К Tsuneo HATSUI, Yuuji ARITA and Relji NAITO Department of Nuclear Engineering, Faculty of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-01* Japan 1. introduction A small amount of La2o3 пав been doped in UO, in order to improve the irradiation behavior such as fission gas release El). The heat capacities o£ gadolinia-doped uOjtUj Gd o2 0, у - 0.044, 0.073, 0.101, 0.142) have been recently measured in the author's laboratory, and an anomalous increase in the heat capacity of each sample was first observed at high temperatures 12,31. In the present study, the heat capacity measurements on Uj_yLay02 (у з Q.044 and 0.142> were carried out up to 1500 К by means of direct heating pulse calorimetcy to discuss the excess heat capacity of doped UO, and undoped UO, in comparison with the data of и,_„<М07. 2. Experimental The mixture of LaO^ 5Q0 and uo2 oon powders was shaped in a cylindrical rod of about 7 mm in diameter and 60 mm in length using an evacuated rubber press with hydrostatic pressure of about 400 MPa. The rod wae sintered at 1573 К for 3 days in a purified Ac gas flow and then at 1323 К for 2 days in a hydrogen gas stream. X-ray diffraction analysis indicated 0 was of ain le that each sample rod of U* ocgba0 тдз ? 9 phase. The heat capacity of U. „La„02 was measured by the direct heating pulse calorimeter, of which the details were given elsewhere previously [41. In this calorimeter, the temperature of a sample rod was varied from room temperature to 1500 К by an external heater, and a current pulse was supplied to both the sample rod and the double cylindrical molybdenum shield simultaneously so as to obtain the same small temperature rise. The electric potential drop, the current and the temperature rise of the sample rod were measured to obtain the heat capacity. 3. Results and discussion An anomalous increase in the heat capacity curve waa of un gggbag i42°2 observed above 900 К similarly to the case of U0.858Gd0.142°2 measured previously in our laboratoryt2,3). The excess heat capacity was evaluated by subtracting the smoothed base line of heat capacity, where the smoothed base line was determined from a least-square fitting for the data in the lower temperature region. Assuming the presence of the contribution of a thermal excited process of the Frenkel defects formation to the excess heat capacity, similarly to the case of Gd doped DO., the formation enthalpy tfiHf) and entropy (uSf> were calculated. The values of йн* and us* 0f U0.858La0.142°2 ace cl0Be t0 those of uo.B58Gd0.142°2' imPlvift9 tnat the 3+ 3+ excess'heat capacities of U02 doped with Gd and La are originated from the same mechanism. The heat capacity measurement of UQ gsgGdg 344О4 is in progress and will be also discussed in relation to that of U0 о58^0 142°2* References 1. J. C. Xilleen, J. Nucl. Mater. 58 (1975) 39. 2. H. ir.aba, к. Naito и. Oguma and~H. Hasuda, j. Nucl. Hater, 137 U986I 176. 3. H. Inaba, K. Naito and H. oguma, J. Nucl. Mater. 149 U967)~T?1. 4. K. Naito, H. Inaba, N. Ishlda and K. seta, j. phys. E: Scl. Instrum. 12 (1979) 712. ~~ 8.3ак.1607 113 THERMODYNAMICS OP QUATERNARY STRONTIUM-YTTRIUM-URANIUM OXIOESl" | T. Yamashita and T. Fujino Japan Atomic Energy Research institute Tokai-mura, IbaraKi 319-11, JAPAN The oxygen potential of the SryYyUi_2y02-».x (Y=0.025 and 0-05) solid solutions was measured by the thermogravimetric method at temperatures between 1123 and 1673 K. in the range of the oxygen potential between -510 and -100 kJ/mol, Co and CO2 gases were nixed and its oxygen partial presuures were continuously checked by a BaTi03 oxygen monitor calibrated in our laboratory. The oxygen potentials of the SryYyUj,_2y02+x {y=0.025 and 0.05) solid solutions are shown in Fig.l. The o/M ratio was calculated from the weight difference between the equilibrium composition and the starting composition which was determined by the cerimetric titration with an accuracy of +0.003 in o/M ratio/-l_7- The oxygen potential becoaes higher as the у value increases; at O/M=2-05 and T-1573 X, the oxygen potentials are -196.6. -165.3 and -143.1 KJ/moi for y=»0, 0.05 and 0.1, respectively. A very rapid increase in oxygen potential is observed at o/M=1.993 and 1.988 for y=0.025 and 0.05, respectively. This observation is quite in contrast to the literatures where the oxygen potential increases rapidly at o/M«2-.GQ. But in a few systems where the solid solutions are formed from uranium dioxide and divalent metal oxides, it i£ reported that the composition at which a rapid increase occurred was shifted toward lower O/M ratio/~2,3j7- The mean valency of uranium at the point of the steepest change is 4.065 for у=0.025 and 4.140 for y=s0.05. figure 2 shows the variation of the partial molar enthalpies of the s*0.05Yo.05u0.9°2+X aolid solution as a function of the O/M ratio. The present results are depicted by open circles and the literature values for U02+x/.~"4'5'6_7» "90.05^0.9502+xZ"2_7 a"d v0.048^0.952°2+x /~6_7 ere also shown for comparison. The enthalpy values for the YO.O48u0.952°2+x solid solution are almoet the same as those for UO2+X' The values for M«JQ , 05u0.95°2+x seem to be situated at the t v; u o Tne midpoint between those for U02+x and ' *^0.05 0.05 0,9 2+X' present solid solution contains strontium and yttrium with 5 at* each but the effect of yttrium addition is very small, and then the large decrease in the enthalpy values from those for иОг+х is considered to be due to the addition of strontium. Strontium shows a larger effect on the enthalpy values than does magnesium. This difference may be ascribed to the larger crystal radius of strontium; the eight-coordination crystal гааша/~7_7 *or Mg2+ is 0.103 nm whereas that for Sr2+ is 0.140 nm, the difference being 0.037 nm, д similar decrease in the enthalpy values was also observed between the YyUi-y02+x and LayUi_y02+x solid solutione/~6j7» 114 ааЛ юЛ Y with 0/H ratio for 8гутуи,_у02*я. ^2+" "9 •»"* •*>«le«. The partial mol^r entropy values for the Sro.05Y0.05°0.9°2+x solid solution were about 145 J'K'imol"1 which are Lower than those for U02+x in 0.0l ASf02) = -4Rln[(2x+3Y/2)/{l-2x-5y/2)j + Q(ss) where the factor Q(ss) includes the vibrational entropies. Using - QB-222 J-K^mol *, the calculated entropy change well represents the experimental values. References 1 т. Fujino and T. YamashitaZ/Fresenius' Z. Anal. Chem- 314 (1983) 423. 2. J. Tateno, T. Fujino and H. Tagawa//j. Solid State Chem. 30 (1979) 265. 3. T. Fujino//j. Hucl. Hater. \bA (198S) 14. 4. Y. Saito//j. Nucl. Hater. 5Ц (1974) 112. 5. S. Aronson and J. Belle//j. Chen. Phys. 29 (1958) 151. 6. К. HagemarK and H. Broli//j. Am. Coram. Soc. 5g (1967) 563. 7_ R.D. Shannon//Acta Crystallogr. ДД2 (1976) 751. 115 тенмхтмас STUDIES ONffb J°4°i2 " Bbi*40i3 SISTBH 3-8 V.S. Iyer, v. Venugopal and D.D. Sood Fuel Chemistry Division Bhabha Atomic Beaearcb Centre Trombay. Bombay 400 085, India Fuel fission product interactions play an important role in determining the integrity of the fuel pin during its life time in a reactor and basic thermodynamic informations on the relevant compounds are therefore desirable. Studies on various compounds using solution calorimetry[lb high temperature Calvet calorimetry[2] and by solid oxide electrolyte galvanic cell[3] are therefore being pursued in our laboratory. Though the fiesion yield of Rubidium is comparatively small, it can tie up oxygen by forming uranates to reduce local oxygen potential of the fuel. Rubidium 0 and Mj 0 uranates of the type Rb4U05> RbgDOj* Rb2U207r *Ь2°4 13 2 7°22 bave been identified in which uranium valency is six (41. With penta^alent uranium the compound reported is Rbuo-j. Attempts for the preparation of Rb2u40^2 analogous to CB2U4012 u 0 from Rb2 4 i3 by Van Bgmond and Cordfunke resulted in a mixture of RbU03 and U02 [4]. Recently Chaw la et al f 51 reported the preparation and characterisation of the B ternary oxides of b-»4012 (H = K* Hb). и According to the phase diagram suggested by Lindemer et al [б] М>2 4°1Э coexists b with Rb2U7022 and U30e under high oxygen potential. If R 2U4Ol3 deomposes to Rb2U4012' determination of oxygen potential over the two phase system would enable the determination of AfGjj, The reversible deonposition reaction : Fb£DAo13isy -^—^ Rb2D4012ts) + 402(g) has been studied by determining the oxygen potential that exists over the system in the temperature range 1019 to 1283 К by a solid oxide electrolyte galvanic cell using air as reference. The galvanic cell is of the type t Pt, Rb2D4012(s) + RbjO^gtsJ/CSZ/eir, Pt where CSZ is calcia stabilized zirconia* Differential thermal analysis studies in argon did not indicate any solifl state transition in the temperature range of the present study, x-ray diffraction patterns on the biphasic mixtures before and after the experiments did not show any new lines indicating the co-existence of the above mixture. The e.m.f.s (E) at different temperatures can given by the equation : Б/mV t 1.7 » 529.0 - 0.3152 (T/K) 116 The measurements have been carried out on three different pellets having different proportions of two compounds. The ejiuf-a obtained at a particular temperature agreed within ± 3 n»V. The above equation is the result of the least squares analysis of all the data. The Gibbs free energy for the reaction : Rb2U4012(s) + %02(g) ^=fe_Rb204013(8} is given by AfG£ Using the estimated values for &f В^<М>2и4013,е,298Л5) and S° (Kb204oI3,s,298.15) from Lindemer et al, AfG^fRbjU^O^rS) and Af<^(Hb2U4012,s) have been obtained. The molar Gibbs free energy of formation has been obtained by UBing the approximation : Af<^(T) •= Д^ (298.151 - T Д£8£ (298.15) 1 and for Rb2U4012(s) Af(f(Rb2U4012»firT)AJ.mol" = -5584 + 1.124(TA) The &fG& values at 1000 К and 1200 К for Rubidium and Caesium uranates are compared in table 1. 1 Gibbs Free energy values Cor t^t^o^ and M2U4012 (M=Cs,Rb) kJ mol" Temperature № U 0 CSjVlS И>2°4°13 c»2u4o12 2 4 12 К 1000 -4460 -4508 -4501 -4509 1200 -4236 -4272 -4220 -4228 Befecenees 1. V.Venugopal, K.K. Shukla, v. Sundaresh, K.w. Roy, R. Prasad and D.D. Sood, J, Cbem. Thermodynamics, 1986, 18» 735. 2. V. venugopal* Renu Agarwal, K.N. Roy. R. Praaad and D.D. Sood» J. Chem. Thermodynamics, 1987, 19, 1105. 3. V. Venugopal, V.S. Iyer, V. Sundaresh, Ziley Singh, H. Prasad and D.D. Sood, J. Chem. Thermodynamics, 1987, 19, 19. 4. A.B. Van Egmond and E.H. P. Cordfunke, J. Inorg. Duel, chem.* 1976, 38, 2245. 5. K.L. Chawla, N.L. Mi era and M.C. Jayadevan, J. Nucl. Hater., 1988, 154, 181. 6. T.B. Lindemer, т.н. feessnannan d С.Б. Johnson, J. Hucl. Mater., 1981, 100, 178. 7. X. One, J. Hucl. Sci. Technol., 1985, 22, 586. 117 THERMODYNAMICS OF URANYH.VIJ WITH SUBSTITUTED АСЕТАТЕГ ~—j LIGANDS I 1 1 A.Bismondo and L.Rizzo Istituto di Chimica e Tecnologia dei Radioelementi - Area di Ricerca C.N.R. - Corso Stati Uniti, 4 - 35020 Padova-ltalia The stability constant and the changes in enthalpy and entro py for the formation of the uranyl(VI)-phenoxyacetate complex have been determined at 25.0 °C using 1.0 mol dm aqueous so lution of sodium perchlorate, as ionic medium. The stability constants were computed by the potentiometric determination of the competitive H ion concentration; the enthalpy changes were determined by direct calorimetric ti trations. The values calculated for tne equilibrium constant and the enthalpy change relative to the protonation of the carboxy- late group are: к" = 1.0S x 103 M"1; 4H " 2.80 kj mol"1. The precipitation of solid compounds allows the determination of the first uranyl(VI)-phenoxyacetate complex only. The com plex is entropycally stabilized; the enthalpy change opposes to his formation. The thermodynamic parameters obtained for this system have been comparated with those determined for complexes with sub stituted acetate ligands (see Table). The uranyl(VI) ion forms 1 : 1 complexes of different stabi lity, which strongly depends on the ligand basicity, whereas the presence of phenoxy group does not significantly affect the stability of the corresponding complex. Further studies are in progress. Comparison of thermodynamic values for the complexation of uranyl(VI) with some monocarboxylates : I = 1 mol dm-3 NaC104, 25'C.,The units for the enthalpy and entropy changes are given in Ы mol"1 and J mol"1 K"1. 118 K AHj /iSj ref Ligand P a l0s/i Aminoacetic acid 2.46 1.16 2.2 3b 1 Chloroacetate 2.66 1.44 8.1 54 2 Phenoxyacetate 3.02 1.70 12.5 75 - Acetate 4.61 2.46 11.8 87 2 References 1. A.Bismondo, L.Rizzo, G.Tomat, D.Curto, P.ui Bernardo, A.Cassol//lnorg. Chim. Acta; 1933, 7£, 21. 2. R.Portanova, P.Di Bernardo, A.Cassol, B.Tondello, L.Magon// Inorg. Chim. Acta; 1У74, &_, 233. ШИИМВЯТАЬ STUDY Of THERMODYNAMIC PROPERTIES OP U°2(0H)2(c) I 3_10' ADD UO,CO,,„4 T.H.Ourevich, C.A.Devin», E. I.Sergeyeva, K.S.Gavrlchev, V.E.Oorbunov, Н.Б. Efimov, I.Ii.Khodakovaky. Vernadsky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Institute of General Chemistry and morganio Chemistry of the Academy of Sciences of the USSR, Institute of High Temperatures of the Academy of Sciences of the USSR, Moscow, USSR u Chemical thermodynamic properties of 02(0H)2y * and UOgCO./* can be treated aa key ones for the U(YI) species existing in aqueous solutions. Ho wever, the liter»ture data oa the thermodynamic properties of D02(°H>2(o) and tf02CO,,o) la very United Two precise cftlorimetrlc methods, low temperature adiabatic and solution- reaction, have been used to determine heat capacity of pure samples of ura- nyl hydroxide and uranyl carbonate (between 10K and 340K) and standard en thalpy of formation of Ш2С0,/о\. The samples of O0j(0H)gfoj and method at 37ЭК. Uranium trloxide (analytically pure) and uranyl carbonate (pure) used for the preparation were purified by precipitation in form of uranium peroxide or uranyl hydroxide. The synthesis wae carried out in high pressure vessels with argon atmosphere in case of U02(OH)2, and with carbon г dioxide atmosphere - in case of UOgCO, ( с0 я* 10 atm). Our determination of the standard molar enthalpy of formation of UOgCO, was based on solution-oaloriaetric measurements of the enthalpy of the reao- tiont' тЛ(л) + 200!(ao,) - D02«°3>3"(aq) The calorimeter aa LKB-8700 model was used. The results obtained have been combined with the other values from the li terature to give, reoommended values of standard volar thermodynamic proper B ties of "0g(0H)2{oj and O2C0,jc» and characteristire of the following equi librist ио2(ов)2-нго(с) . иог(он)2(о) + нго(1) . D02003(C) + V(l> • D02<°W2(o) + 002(g> • The 'equilibria constants obtained from the oalorimetric data «ere compa red with the results of dtroot experimental measurements. 120 COMPLEX FORMATION OF U(IY) AND U(YI) IK AQUEOUS SObUTIOBS IN THE 3-11 RANGE 25-600°C AND 1-1000 BARS (EXPERIMENTAL STUDY) B.I.Sergeyeva, M.I.Savelyeva, A.P.Red'kin.A.V.Zotov, B.I.Omelyanenko, I.P.Ivanov, I.L.Khodakovsky. Vernadsky Institute of Geoahemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Institute of Experimental Mineralogy of the Academy of Sciences of the USSR, Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry of the Academy of Sciences of the USSR, Moscow, USSR Complex formation of uranium (1Y) and (YI) in aqueous solutions has been investigated by spectrophotometry and solubility methods Solubility of uraninite (UOg) in H,0 and aqueous solutions of RC1 (0.0001 Янс1:1-0 mole/kg HgO), K01+B01 (i.00Cmg^«1.10 mole/kg H20) at 300, 400, 500, 600°C and P=1 kbar has been measured. The f0 values were controlled by hematite-magnetite or nickel-nickel oxide buffers.2 The results obtained show that U02(c) solubility in pure H20 does not pra ctically depend on temperature (and on the kind of buffer as well) in the te mperature range stud'.ed and averages to logs—9.0*0.5- Uranlnlte solubility essentially increases in acid chloride solutions. The following dissolution reactions in the Investigated temperature and pB-range has been proposed: U02/c, + 2HgO « U(0H)./ N ff02(o) + *<•«> + ¥(1) " «0H>3(aq). C0 D02(OH),y . solubility in HgO at 100°C (in Ar-atmoapnere) and U°2 3(C) solubility in HgO and aqueous solutions of NaHOO- (0,001-0,1 K) in 002 atmo sphere, 7,7* PgQ^ 20.93 atm, at 100 and 200°C has been measured. UO^-COn-R^O system has been studied spectrophotometrieally in the range 25-80°C, P00 « 0.97-0,52 atm and 0.1-2.0 (NaOlO.) molal ionic strength. Vi sible spectra (400-490 am) of U(YI) carbonate solutions has been measured. The concentration range investigated: ощух)' 2*1° mole/kg HgOi 0.015$ "NaHCO*0-1' Mi 5.15*oH47.35. The third stepwise formation constant (K-) of U03(CO3)3*- : U0a(0O3)2f;q) + COjf^, - UO^COj^ baa been derived as a function of ionic strength and temperature: 0 -1 lg K3°e 3193/* - 6.22; дН^ - - 61 fcNmole , The experimental results combined with literature data permit to refine D 4 q thermodynamic properties of complex compounds (U0o}_C0H)J. " , U0o(C04)n , U(0H).^"4, existing in aqueous solution* in the themperature range investi gated. 121 THERHODYHAHIC PROPERTIES OF PLUTOHHIM IHTERMETALLIC COMPOUNDS v.i.Kober, I.P.Uitchkov, S.F.Raspopin, G.H.Kazantsev. Urals Polytechnical Institute, Sverdlovsk, USSR Thermodynamic properties of intermetallie compounds of plutonium with low melting-point metals (НШ1) were studied by an ЕИР technique using the gal vanic elements Pu-In. | KOI - UC1 + Pa3+| Pu-Me в.в.* a.e.i where Me • Al, Oa,.Sn. Sb, Pb, Bi and a.s. » a saturated solution. The data on thermodynamic properties of Pu-IMPM compounds had been generalized in /17. Usage of Pu-Bi saturated solution in equilibrium with which was the PuBi, intarmatallie compound with known tharnodyaanio properties &] permitted the temperature dependence of ЕИР to be calculated for Pu-Me saturated solutions with respect to 2-plutonium. The EHP technique is known to provide direct information about changea the Gibbs energy of the eleotroaotive component-as the latter changes from the metallic state ( i-plutonium standard state) to an 1ИРМ with the foriaa- tion of saturated solutions that are in equilibrium with IMPM-rich Interne ts lli с compounds: **«(.) + №(1) ~ »,(,). The electrolytic cell, the experimental technique and the data analysis procedure were similar to those described by us in Ы. Electrolyte was pre pared of dehydrated individual seltB. Plutonium trichloride was obtained by chlorinating PuOg. The Plutonium content of the ШРМ exoeeded the vs-lue of Pu solubility at the highest temperature involved, which corresponded to the diphasic stats of each alloy. Experiments were performed in helium atmosphere. Helium was cleaned of moisture and oxygen hy passing it over a getter of ura nium chips at 1070 K. The estimated values for the thermodynamic properties of plutonium-UIFK intermetallic compounds are given in the Table. Thermodynamic Characteristics of Fu-MIFM Compounds Phase *T, К **Pu. kJ/mol J/mol к Al + PuAl. 803-913 190.7+7.5 49.9+7.9 U+ PuAl4 232.2+7.5 94.7+7.9 L * PuOag 640-965 217.8 52.7 t, + Tuln* 640-960 198.7+7.1 В5.4+Ю.О L + PuSnj 640-960 237.2 вг.г Sb + PuSb2 808-89S 279.1+5.0 72.8+8.0 i/ + PuSb 319.3+5.0 117.2+8.0 2 - L + PuPo, - 224.9 81.1 i. + PuBlg 694-780 208.7 53.3 V + PuBig 780-833 223.7 72.7 122 The SH? temperature dependences of Pu-LMPM alloys follow the pattern for the corresponding light REM-IMPM alloys. Based on this, the unknown valueAS^ for the PuFb, alloy is equated to the value Д Sj^ for the PuSn, compound. The values of Pu-Ga alloy potentials aa compared with those of the PuBi. compound are more positive than in the case of the REM-IKPM «here it Is the REBOa, compound that is the ЬМРИ-richest one in the system. Together with the data on the presence of the PuOa,. compound in the Pu-йа system, this fact rirovideB evidence that the compound studied in equilibrium with saturated The data on the phsse composition of Pu-Al alloys were obtained using the potential-vs-tjne variant of the EMF method. The potential-vs-time curve clearly displays aix influxions of the potential of a solid aluminium electrode coated with plutonium relative to L +PuBi . In accordance with the data from [2] the infliction at 560 oV corresponds to the deposition of metallic plutonitnn on solid aluminium. Subsequent in* fluxions are due to the formation of all compounds in the surface layer of the eleotrode owing to the interdiffusion of aluminium and plutonium atoms. In accordance with equilibrium measurements of EMP the potential of the Al+PuAl. diphasic alloy at 818 к la 518 mV and differs from the results ob tained by the potential-vs-time method by 26 mV only. Five Pu-Al compounds and discrete values of partial Gibba energy for Pu B.mV in the compounds PuAl,, PuAl , PuAl , PuAl equal to -13B.9i -123-6? -117.0; -110.0j -35.9 kJ/mol, respectively, can be represented, in terme of interatomic interactions, as a process of successive too completion of vacant 3p orbitala in the acceptor atoms of aluminium by valence electrons of plutonium atoms so that о е. зав filled 3s*3p° shells are obtained A7- Ten compounds (and not eleven) in the "V Pu-Ga system are due to the completion of the Gs acceptor atoms by 3d shell *• aa ejmtn electrons until a 4sz(4p3d)* bonding Pu Coated Aluminium Electrode Potential Veraus Time configuration is formed. References Chiotti P. et al.//The Chemical Thermodynamics of Actinide Elements and Compounds. Pt 5. The Actinide Binary Alloys. Vienna: Int.At«Energy Agency. 1981. P.214-260. Lebedev V.A. et aW/Atom.Energ. 1969. Vol.27, N 1. P.59-61. Kober V.I. et al.//Zh.Piz.Khimii. 1985. Vol.59- P.2124-2126. 4. Kober V.I., Nitchiov I.F.//Izv.AN SSSR. Metally. 1975. H 4. Р.229-2Э1. 123 EFFECT OF THE SURFACE COVERAGE OH THE ISOSTERIC BEAT OP PuPg ADSORPTIOH OH PuP. [ЕП I.Yu.Mareev, V.P.Serik. Kurohatov Institute of Atonic Energy, Moscow, USSR Regeneration of Irradiated nuclear fuel by the fluoride method assumes that some processes involve plutonlum tetra- and hezalluorides at a tine [1] . Since the effeots of adsorption will Inevitably take plaoo in suoh a system, their quantitative study la of indubitable interest. It should be noted here that during adsorption of gases and rapoura onto the surface of solids the adaorbate-adsorbent interaction is always followed by the adsorbate-adsorba- te the fraction of which она appreciably increase due to adsorption of oom- plex polysleotron molecules. With the complexity of the oaloulatlen of in- texmoleoular Interactions and the passible iahomogenelty of adsorption cen tres la energy taken into account, the preferenoe given to the experimental determination of the Isosterio heats of adsorption beoemes evident. In vir tue of the above factors they can depend on the surface eoverage. The adsorption isotheras for PuPg on PuF. at Tj«29BK and T2«313K were ob tained in the present work. PlutonlUB tetrachloride used In the experiment has a speolfic surface of 16.9 mVg* The isosterio heat of adsorption was calculated from the formula [г] : Q -jJl-jjSRlntPg/p, )r , where Q is the heat corresponding adsorption of Г moles of PuFg in eal/mole; в • 1.987 oal/ (mole.grad); Tj.Tg are the temperatttree of Isotherms In K; P1 and Pg are the pressures corresponding to adsorption of Г moles of PuPg at temperatures T, and Tg respectively, in Torr. The processing of the first part of the 298 К isotherm of PuPg on PUP. with the use of the ТяпвииДг equation gave 44.1 * . for the area of PuFg mo lecule in the dense monolayer. The analysis of the data obtained ahowed that the ieosteric heat of PuFg adsorption on PuP. reaches the marimim value в„-1г.5 kcal/nole at a surface ooverage q • 0.32, than deoreases to Q>11.8 kcal/mole. Since the heat of eublimatirn of solid FuPg {11.5 kcal/mole [i] ) is comparable with this value. It Is possible to assume that adsorbed PuPg is In the solid state within the temperature range studied. For Q • 0.10- 0.31 the initial rise of the curve resulting probably from the intemoleou- lar interaction of adsorbed PuFg san be desoribed to an aoouraoy of about 5% in the forai Q. • 7.2+178, where Q is the heat In koal/ooleiS is the sur face ooverage. References 1. Galkin N.P., Ponooarev L.A., Shishkov vu.D.//Radiokhomiya. 1980. T.22.S.754. 2. A Course of Physical Chemistry/Ed Ya.I.Gerasimov. If.: Khlmlya, 1969. 3. Plutonium Handbook. A guide to the Technology/Ed.O.J.Wick. N.Y.: Gordon and Breach, Sci.Publ., 1967. 124 OH ABSORPTION О» РШОВШВ ADD PLUTONIUM HEXAPLUORIDE 3-14 OH PLUTOBIUH TBTRAPLUORTDE I.Yu.Kaieev, V.F.Settk. Kurchatov Institute of Atonic Energy, Moscow, USSR A oomplex of work» in the field of ohemistry and physical ahemistry of Plutonium fluorides is needed to develop the fluoride method of Irradiated mtoleox fuel regeneration [l] . Slnoe the ternary system Pg-PuFg-PnPj Is Involved In fluorlmrtion of plu- tonlvra tetrsfluoride, thermal and radiation decomposition of Plutonium hexa- fluorld» [2J , the problem of adsorption of fluorine and pJutonlum hexafluoride on the surfaoe of plutonlumtetrafluorlde la of obvious scientific Interest» Adsorption of fluorine and plutonlum hexafluoride has been studied in this work at temperatures of 77.8 К and 298 К respectively. Plutonium tert- rafluorlde used as a aorbent had a speelfls surfsos of 40.7 m /e in the first ease and 16.9 m /e In the second one. The experiments showed that adsorption of P2 on PttP, Is deseribed well by the Lasemulr isotherm [3] f/aal/a^E + P/a^, where P is the pressure in Torr, e-is the amount of adsorbed gas in mole.10" , a,, Is the amount of adsorbed gas In a dense monolayer In mole.10 , К is the constant, вц'197.10' mole and KwO.924 Torr were obtained for a total surfaoe of PuF. equal to 20.0 or. Ша area per molecule of fluorine In the dense monolayer calculated from the above values proved to be 16.BA 2. At a fluorine pressure of up to 2.5 lorr the equation described the adsorption with, an average relative error of 1.6%. Adsorption of PuPg on PuP. at a temperature of 298 К and a pressure of up to 4.0 Sorr also followed the т^.дч.ч» isotherm (to an aoouraoy of 3.5%). а^авЗ.Э.Ю mole and К»0.Э5Э Torr were obtained for a total surface of Pup, equal to 22.3 m . The area per moleouls of fluorine In the dense mono layer amounted to 44.1A . References 1. Galkin N.P., Ponomarev L.A., ShiBhkov 5tu.D.//Hadiol£himiya.1980. T.22.S.754, 2. Plutonium Handbook. A Guide to the Technology/Ed.O.J.Wick. N.Y.: Cordon and Breach. Sci.Publ., 1967. 3. Brunauer S. The Adsorption of Caaea and Vapors. Princeton Univ.Press, 1945- 125 THERMODYNAMIC PARAMETERS FOR THE REACTION 3+ + 4+ 3-15 Me + H -«+- Me + V2H2 ( Me = Bk, Ce ) IN VARIOUS SOLUTIONS G.A.Timofeev, V.M.Chistyakov, E.A.Erin, A.A.Baranov. Research Institute of Atomic Reactors, Dimitrovgrad, USSR This paper presents both the results from the comparative measurements of the oxidation potentiales for BkUV) -Bk(IIi) and Ce(iv) - ceUHJ reversible pairs in various solutions within the temperature range from 8 to 50°C and the estimations of the thermo dynamic parameters - Gibbs' energy, ^G j enthalpy, дН , and entropy, дБ, for the reaction 3 4+ Me * + H* •++ Me + 1/2 H2« (1) The &G values for each temperature were calculated from the experi mental Ef data according to AG = -96.485 Ej . (2) It has bean stated that in all the cases the temperature dependence of all the calculated AG values are straight lines. Prom these lines slope to abscissa the values foraS were obtained. And then according to AG - fcH - T*S (3) -he changes in enthalpy were calculated. Table I presents the values of the reaction {I) thermodynamic parameters for berhelium and cerium in the solutions of perchloric» nitric, silphuric, phosphoric acids as well as of sodium and potassium carbonates. As it is seen from the Table when 1 moi/ 1 HCt04 converts to 1 mol/4<2C03 the absolute A,G and AH values for both berkelium and cerium decrease and those ofj&S change the sign. The mode of changes in the thermodynamic parameters of the reaction suggests that the thermodynamic stability of four-valent berkelium and cerium increases considerably while passing from perchloric acid solutions to those of carbonate. In the carbonate solutions AG values decrease so that berkelium(III) and cerium(IXi) are oxidized in air. During the experiments we observed this according to gradual growth of the oxidizing potential, Efc, measured with an indicator platinum electrode in the electrochemical cell containing the Bk(III) or Ce(IH) carbonate solutions. It is significant that with the increase in the nitric acid solution concentration from 1 to в mol/l the дв and дН values for reaction (1) with berkelium ions present are not practically changed» Thus, with the nitric acid solution concentration up to в mol/1 berkelium (IV) is unlikely to form the inner-sphere nitrate complexes in contrast to other four-valent actinoides and cerium. Thermodynamic Parameters for the Reaction Me +*T-«-Me*"""* 1/2H- in Various Solutions Bk ce Medium Л<= a.H «s AG дН as kJ/raol kJ/mol J/K'IBOJ kJ/lROl kJ/mol J/K.mol s Bdo4, 1mol/l 153.7*0.8 116.0*2.1 -126*8 163.7±0.8 145 2 -63.8 1во1 1 152.0±0.в loot в -176±2! 159.1*0.8 130*4 -92l3 HN03, / HNO3' 6m°1/1 151.6*0.8 • 1.09*4 -•134*13 --- HH0 / 8mol/l 148.6*0.8 -147±2! 3 105±8 -- H2304, 1mol/l 133.1*0.8 113±10 -67 ±33 139* 0.8 128*2 -38*8 H3P04, 4mol/l 108.9*0.8 109*3 -7* 23 iisio.8 105*4 -33±13 Na-CO,,1raol/l 22.6*0.8 59+8 126±29 15.S*o.8 46*4 105*21 K.COj, 1in0l/l 22.2*0.8 63*8 134±29 13.0±O.8 46*8 105±25 THE THERMODYNAMIC OF SOHPTIOH OP SOME ACTIMIDES BY AHIOH EXCHANGERS! | l.L.Borin. Polyteonnical Institute, TomaJc, USSR \_Z I for the reaction of eorption of в neutral complex MAn Ъу the A form of anion exchanger HA (1) mRA HWa-RJUVa, r , a rigorous thermodynamic treatment has been previously proposed [ 1 J • The va a а a шау lue of the thermodynaaic equilibrium constant Ka« RMA /С дд MA* be calculated on the basis of the treatment from the following equation йщМАп+т RpiMAn+m UnMAn+m + + 1 a ( y = ^V^KA^KA ^^«X "^нго^^нго - « MAn *J**** « mlj^ + mljj + ml^o - Iga^VV-ffl) * (2) where KA is ligand salt or ligand acid,?^ is a number of moles of the compo nent i per equivalent of anion exchanger, a^, a^ , ацQ are the activities of the distributable components in the aqueous phase, ауд (ИщМА^^) is the activity of the salt MAn in the aqueous phase in equilibrium with resinate RmHAn+m* All data needed for the calculations of the values Ka by means of eq (2) have been obtained from the equilibrium experiments carried out at25°С by the author and hie coworkers.Anion exchangers used in the experiments were the quaternary amine reein AV-17x8 and the quaternary phosphine resin ChPO. Several iterative computer programs written by the author were used for the calculations of a„. with the Lewis equation from the values of the thermody namic stability1 constants of complex formation in the aqueous phase* For some systems there were available necessary data in order to calculate e a /(a a ) for the the values of K£ - RmMAn+m A- 1iAg;]n RA »•«*«» *** + MA£m = s ILMA^_Hn+ mA". The calculated values of lgKa, lgK^ and standard Gibbe ener gies^0 andeO'0 are given in the Table. R2Pu(iTO3)6 was calculated on the basis of the data [2 ] . . thermodynamic Equilibrium Constanta and Standard Gibbs Energies Anion Pinal resinate lgK 40 45 Exchangers йщМАп+т lgKa a •55T "'ЕТ 6.05*0.05 AT - 17x8 R4uo2(so4>3 -эЧ.й+о.Зо 5.13*0.05 4.29*0.05 -24.4S+0.30 нгиог<зо4)г -29.31+0.30 12.67±0.06 10.23*0.06 -58.39+0.35 R«OaF3 -79.32+0.35 £7.3*0.2 25.70*0.2 -146.7* 1.2 R№5 -155.811.2 -0.840.3 R2Th(TO3)6 4.57+1-7 1.52±0.09 ChPO RzTh(N03)g -8.68+0.51 3.00*0.10 Dowex 1x4 R2Pu(S03)6 -17.12+0.60 References 1. Borin L.L. Termodinamifea geterogennikh proceesov s uchastiem anionnikh komplexov aktinoldov. Ы.: finergoatomiadat,1985 . 2. James D.B.//J.Inorg. Nucl. Chem. 1963. Vol.25. P.7*M* SOLID STATE PHYSICS AND CHEMISTRY 9.3ак.1607. •^L-Щ"' THE MAGNETIC TRANSITIONS IN THE ACTINIDEJ?RANSITION-MEI!AIi-TERNARIES „ . ' 4-1 ) R.Troc, V.H.Tran, Institute for Low Temperature and Structure I—. 1 Research, Polish Academy of Sciences, P.O. Box 937, 50-950 Wroclaw, Poland V.Sechovsky, L.Havela, Department of Metal PhyBics, Charles University, Ke Karlovu 5, 181 16 Prague 2, Czechoslovakia A.V.Andreev, Ural State University, Sverdlovsk, USSR There exist hundreds of various intermetalllc compounds based on the light actinldeo, namely U, Np or Pu C\,7^. The specific ingredient of these mate rials are 5f electrone, the character of which can range from itinerant to nearly localized one, depending on some factors. Among them there are: the interatomic spacing, the strength of the interactions of the above electrons with the ligand a-, p_, d-electrons and the number of different atoms in the chemical formula as well ae their mucual ratios. All the above factors decide about the extent cf the 5f electron derealization. In other words, the mag netic properties of these materials can be considered as being government by an effective 5f bandwidth (W„) controlled mainly by both the overlap of the 5f orbitals and so-called Sf-ligand hybridization /57. When reviewing ground state electronic properties of aotlnlde binary ln- termetallicB, starting from An-rich compounds (6:1, 3:1,..) and further low ering the An-content, we meet the stable 5f magnetic moments and magnetic or dering first at equlatomic compounds, namely Ulr, UPt, JfpPt, PuPt and US1 (or in nsa-eojuiatomic U^Ge^). Much more opportunities to study the onset of the magnetic ordering Is, however, provided by numerous ternary, also equlatomic, AnTX compounds, where T represents a late transition- (from Fe to Pt) and x a p-electron metal (Al, Go, Sn, In) or a demi-metal (Si, Ge,...). These 1.-1.-1 compounds are formed in several structure types. Their occurrence for U-based compounds is shown in the Figure below. I' I Pe Co Ni Cu Ru Rh Pd Pt Mg 2п2~пехав* hexag. MgAg As-cubic (TiNiSi)-orth. or Caln2-b.exag. The shortest U-U distances were found for the UT(Si, Ge) compounds (3.4- 3.6 A) what place them almost exactly on the so-called Hill limit. Slightly larger U-U spacings occur for the UT(A1, Ge) -ternaries (3.6-3S A), while the largest ones are characteristic for Ut(Xn, Sn) compounds (3.8-4.1 A). Measurements of bulk properties of UTX compounds, namely the temperature variations of the magnetic suaoeptlbillty XW, the electrical reslBtivity c(T) or magnetoreslstlvity Д/>(Т)/у>(Т), the specific heat 0 (T, H) in mag netic fields up to 5T, and the magnetization H(H) in magnetic fields up to 40T, have revealed a variety of magnetic characteristics ranging from a weak paramagnetism, more or lees dependent on temperature, to different types of magnetic ordering of stable 5f magnetic moments J2,ij. Ground-state properties for the two largest isostructural groups of Fe^P and CeCuo-types studied here, exhibit the following general features* 130 a) No trace of the d-magnetism has been detected in all ternaries studied. b) The highest ordered and effective magnetic momenta per U atom, exceed ing 1 and 3 i^g. respectively, are found in the compounds containing T metals with nearly filled d-states, i.e. In U(Ni, Pd, Pt)X; both ferromagnets and antiferromagnets are strongly anleotropic (fi0HA > 100T) which ie related to the 5f origin of the magnetic moments. c) For the compounds containing T metals but.with mostly reduoed d-ooeupa- tlon (Pe, Ru and sometimes Ir) either only magnetic correlations survive in the form of spin-fluctuation effects (URu(Al, Ga, Si, Ce) and UlrSl) or we deal with the weak (UPeAl) or strong (UCo(Sl, Be) and UCoAl) paramagnetism. Oa& of the most spectacular features of these ternaries is a huge magnetic anisotropy found already In the oaae of the non-magnetic state of uranium* d) As one could expect, the magnetic properties become more pronounced in the succession: Al, Ga, Sn (In)- for the hexagonal FejP-type compounds and Si, Ge- for the orthorhomblc CeCug-type. Baeed on the experimental results obtained for these groups of ternaries and comparing them with the experimental and theoretical data of other in- termetallic binaries, like IK- and UTj, having a large T/U atomic ratio we have come to the following conclusions: The electronic structure (and hence aleo the magnetic properties) of the above ternaries is controlled first of all by two band regions, i.e. by the wide and narrow bands with predominant T-d and u-f character, respectively, where the latter band always appears to be pinned i.t or near the Fermi energy Ep. The uranium atom donates a part of its valenoe electrons into the T-d bands and owing to the small U/T atom ratio in the UTX compounds, the latter bands are becoming almost or completely filled and therefore they move more or less away from-.Ep, depending on the Initial number of holes in the d-band of T-metal. This implies a gradual reduction in the hybridization, finally stabilizing the local magnetic moment behaviour even for oases of small U-U distances (e.g. around 3.5 A) in comparison to those in other uranium in- termetallice (usually above 4 A) for which the T/U atomic ratio la consider ably larger then unity. Far-example, the 5f electrons in the 1:3 uranium in- termetalllcs, like V(Si, Ge), or V(Ru, Eh, Pd, Ir, Pt)j, (where the U-D spaclngs are higher than 4 A), hybridize with the p-or d-states, respecti vely, so strongly to yield the temperature independent paramagnetism, observ ed in these compounds over a wide temperature range. Finally, It аветв that the strong magnetocrystalllne anisotropy observed for the ternaries even with the non-magnetic ground state of uranium is probably associated with the enisotropy of Sf-llgand hybridization (besides 5f-5f overlap) giving rises to a strong anisotropy of the Fermi surface. References 1. Fournler J.M., Troc R. Bulk Properties of the Actinldee II Handbook on the Physics and Chemistry of the Actinldes / Sd. A.J.Freeman, G.H.Landor, North Holland. 1984. Vol. 2. Р. 29-17Э. 2. Sechovsky V..,. Havela L. Intermetallic Compounds of Actinides // Ferro magnetic Materials / Ed. E,P.»ohlfarth, K.H.j.Bueohow. North Holland, 1988. Vol. 4. P. 309-491. 3. Koelllng D.D., Dunlap B.D., Crabtree G.W. // Phys. Rev. 1985. Vol. B31. P. 4966. 4- Troo R., Tran V.H. // J. Uagn. Kagn. Mat. 1986. Vol. 73. P. 389. STRUCTURAL TRENDS IN ACTINIDB CHEMISTRY ._2 Gabriella Bombieri IstitUto di Chimlca Farmaceutica, Univeralta* Di Milano, Viale Abruzzl 42, 20131 Milan, Italy The structural chemistry of the actlnide elements has recently undergone considerable development and a wide variety of coordi nation numbers and geometries have been observed,This structural versatility arises from the lack of strong crystal field effects for the 5f-electronic configurations, as well as from the large ionic radii of these metal ions which change markedly with either oxidation number or atomic number. Accordingly, the coordination numbers and geometries of actlnide complexes are determined pri marily by the denticity, geometry and steric bulk of the Uganda. utamples are the monodentate, sterically hindered substituted ureas andamidee and the polydentate sequestering ligands. A criti cal survey of the various structures observed for these complexes is presented ana the relevant structural trends are related to steric and electronic effects. 132 ANTIFERROMAGNETIC aUCTUATIONS AND HEAVY 4-3 ELECTRON SUPER CONDUCTIVITY г M. R. Norman, Materials Science Division, Argonne National Laboratory, Argonne, IL 60439 USA* The current status of theory for heavy electron superconductors is briefly reviewed. Emphasis is placed on those theories which propose antiferro- magnetic fluctuations as the pairing mechanism. The observation of strong antiferromagnetic (AF) fluctuations by neutron scattering in heavy electron superconductors, as well as the subsequent discovery of weak moment spin density wave ordering in the same metals, has led many theorists to consider AF fluctuations as the pairing mechanism in these superconductors [1]. It was suggested by the author that the band structure Fermi surface combined with information on the dynamic susceptibility, %(q,«>), from neutron scattering data could be used as input to the appropriate gap aquations [2], The resulting solutions have nodal structures for the superconducting gaps consistent with experimental data, as well as providing reasonable estimates for the transition temperature. Recent work has focused on determining the exact symmetry of the gap function, and what this implies for various experimental data for UPt3. The earlier work of Ref. 2 ^ ;y included the kz dependence of z(q), and found an Aig symmetry for the gap. Recent work by Putikka and Joynt including the kx and ky dependence find E-)g solutions [3]. Neither of these gap functions, though, have proper lattice periodicity. This can be corrected by properly including Umktapp processes, again leading to A1g solutions [4]. Both A1g and E-|g solutions have a nodal structure consistent with thermodynamic data (line nodes perpendicular to the kz axis). The Ejg solution, though, has the advantage of possibly explaining the existence of a second phase transition seen by longitudinal Ultrasound, since it is a two-dimensional representation. An alternate explanation based on a change in the spin density wave order parameter may also be possible. More theoretical and experimental work will be needed to clarify this matter. For the case of UBe^, solutions of A^g, E-jg, or mixed Ajg-E-jg character have been calculated [2]. The E1g solution has point nodes, consistent with thermodynamic data. Mixed symmetry solutions have been proposed by a number of theorists to explain a second phase transition seen in Th-doped samples. The most recent work indicates, though, that the E1g component 'Work supported by the U. S. Dept. of Energy, BES-Materials Sciences, under Contract No. W-31-109-ENG-38. 133 might need to be replaced by a three-dimensional representation [5]. Simple anriferromagnetic correlations only allows A^g-E^g, but recent neutron scattering data Indicate that x(q) may be quite complicated, allowing other representations to enter. In conclusion, antiferromagnettc correlations are providing a good frame work for interpreting various experimental data for heavy electron super conductors. The interplay of theory ?nd experiment will hopefully lead to a better understanding of these metals in the coming years. References 1. K. Miyake, S. Schmitt-Rink. and С M. Varma, Phys. Rev. В 34,65S4 (1986); С. J. Pethtek and D. Pines, in Novel Superconductivity, eds. S. A. Wolf and V. Z. Kresin (Plenum, Nei • York, 1987), p. 201; P. W. Anderson, in Theoretical and Experimental Aspects of Valence Fluctuations and Heavy Fermbns, eds. L. C. Gupta and S. K. Malik (Plenum, New York, 1987), p. 1. 2. M. R. Norman, Phys. Rev. Lett 59,232 (1987) and Phys. Rev. В 37,4987 (1988). 3. W. Putikka and R. Joynt, Phys. Rev. В 37, 2372 (1988) and Phys. Rev. В 39. xxx (1989). 4. M. R. Norman, submitted, Phys. Rev. Q. 5. M. Sigristand Т. М. Rioe, Phys. Rev. В 39, xxx (1989). 134 THE FORMATION OF MIXED COSDENED CLUSTERS OF THE HjClj TYPE P4I4 BY ACTIMIDES AND bARTHASIDBS N.B.Hikheev, A.N.Kamenekaya.I.A.Humer. Institute of Physical ChemlBtry of the Academy of Sciences of the USSR, Moscow, USSR Over recent years the synthesis and properties of the cluster compounds of various metals have been intensively studied. Such compound a are known both for d-elements and some other lanthanides /V. d-Bleetrone have been shown to take pari, in the formation of the Me-Me bond /2/. An assumption has been made about the decisive role of the divalent lanthanldee with the f°" d configuration In the formation of oondensed clusters Л7. Яр +, Pu +, Cm and Y2+ have the analogous configuration in the condensed phase, while Am has the fnd° configuration. The study of the behaviour of these elements In the process of thr.- formation of the G&2CI3 clusters provided Interesting data allowing conclusions to be made about the mechanism of the GdgClg formation and the possibility of the existence of clusters of actlnide elements. The cocrystallization of Up, Pu, Am, Cm, Eu and Y with GdgCl. in the sys tem Cd°-GdCl, has been studied at 1O00K. It has been established teat Am as well aa Eu praotically are not trapped by the GdqCl- phase, which is due to the electron fn"1d° configuration in the oxidation state 2+. At the same time ITp, Fu, Cm and Y cocrystallize with GdmCl». The transition of the ele ments to the GdgCl, phase decreases with an Increase In the reduction of these elements up to the oxidation state 2+. There nave been obtained an equilibrium describing the distribution of the elements under study between Gd2Cl, and the melt. Baaed on the study of the cooryetallizatlon of miorocom- ponents a conclusion has been made about the mechanism of the formation of the GdgCl- cluster OJ• References 1. Simon A. // J. Solid State Chen. 1985. Vol. 57, !J 1. P. 2. 2. Eoelnghaua G., Simon A., Griffith A. // Z. Haturforschung. 1982. Ed. 37a, H 6. S. 564-567. 3. Mlfcheev tf.B., Simon A., Mattauseh G., Keller a. // Z. Ifaturf orscnung. 1984. Bd. 42b. S. 666-668. 4. Klkheev Л.В., Kamenskaya A.H., Rumer I.A. // Hid All-Union Conference on Chemistry of Tranaplutonium Elements* Abstracts of Papers. Dmitrovgrad, 1988. P. 54-55. 135 THE REGULARITIES AND MECHANISMS OP DIFFUSION PROCESSES IK ACTINIDES СЕЛ E.A.Smirnov, K.E.Smirnov. Moscow Engineering Physics Institute, L.F.Timofeeva, V.V.Sipln. All-Union Research Institute of Inorganic Materials, Moscow, USSR Due to a great variety of crystal structures of allotropic modificat ions of aotinides essential differences in the levels of diffusional mo bility and parametreo of diffusion processes (DP) investigated up to now for a relatively narrow range of "light" aotinides In, U, Яр and Pu are observed. She fewness and contrarieties of the results of there in vestigations reviewed in [1^ have been hindered of the regularities de- tendUiiiig and interpretation of fundamental mechanisms of DP whose ano malies ars connected with the peculiarities of this group of elements electronic configurations. The aim of this work is gaining understanding of these problems as well as widening the range of investigated materi als. The salient characteristics of DP in BOO phases of actinides are an anomalous high level of diffusional mobility and low values of paramet ree D? as compared with the "normal" BCC metsls. She self-diffusion co efficients CSC) at comparatively temperatures depend substantially on the value Cr_V0 proportional to the elastic energy of the lattice defor mation at the diffusion jump [г], where Gg is the shear modulus and VQ is the crystall cell volume at О К (Fig.b, c). The temperature depen dence of all the measuted up to now SC in BCC phases of actinides are plotted in Fig.b and can be presented analltically as: г lg D* . -1.68-9.15х10 (G^V^S), where Q*.(0.18.£0.05)CoVo (eV), which is in accordance with angle coefficient of line 2 in Fig. с for the most trustworthy data. Apparently this is connected with anomalous low modules of elasticity of BOO phases f-elements and confirms the existence of interstitial configurations contributions in 1*[з]. She op portunity of this mechanism DP have been confirmed also by data on ef fect of hydrostatic pressure an SC in e-Pu end S-Ce. She presence of great lattice relaxation effects allow to admit the realization of in terstitial mechanisms without of the "activated" defects model |*4J. She dependences of SC in close-packed (CJ) phases of plutonium with the anomalous behaviour on T™/S, where Tm are calculated melting tem peratures of CP phases, are given in Fig.a and expressed in the follow ing form: Ig D* « -iO.Uip. 14)47.57+0.11).(S°p/S), where Q* - O.5i±0.02)x10"2 sj*p (eV), 136 The temperature dependences of SO in the actinides: a) CF phases of Pu (1) and for comparing f-Ов (2), JS-U (3) and oCJJ (4); ь) ВСС phases; c) dependences of SO in actinides at 0.8 Тщ В0С phases (1) and activation energy of self-diffusion in SCO (2), CP (3) phases of aetiaides and "normal" CP metals (4) on elastic energy of lattloe deformation and are in agreement with the results of investigation DP in CP phases of all anomalous metals from transition and lanthanides groups [2l« She analysis of point defects characteristics and possible mechanlaas of DP in OP phases of all anomalous metals allow to suppose the probability of contributions in DP of the complexes "vacanoy-interstitial Impurity atom" [a]. References 1. Pedorov G.B., Smirnov E.A. Diffusion in Reactor X&teriala. Hew Delhi-Calcutta: Oxonian Press, 1984. 170 p. 2. Smirnov E.A., Smirnov K.B., Krylov I.L., Shevcbuk Yu.A.//Sroc. Intern. Conf. DIMETA-88. Hungary, 1988. Mater.Sol. Forum, 1989. 3. Smirnov E.A., Hetallurgiya i metallovedeniye chistych metallov. U: Atomizdat, 1980. P.105-116. 4. Comet J.A. // These doot. aci. phys. Гас. Scl. Orsay Univ. Paris, 1970. 67 p. 137 X-RAY INTENSITY FORJH-, L-SERIES OP ACTIKIDE ISOTOPES 4-I~~] Yu. S.Popov, G.A.Tlmofeev. Research Institute of Atomic Reactors, Dimitrovgrad, USSR The radioactive decay of all actiniae isotopes ie aceonpalned by the characteristics X-rays for M-, L-series. Great practical interest ie created in application of this X-ray type for identifying the actinide isotopes. The relative intensities of X-ray for H-, Ь-eeries in thorium to fermium row measured by the same spectrometer are tabulated. Before preparing eourcea for measurements the aotinides were radiochemically purified. X-Ray intensities of Actinide Ieotopee Hadioisotope, principal Inten&itlee for series lecay scheme H L 2 32ть -2i„«eRa — ^ 57(6) 100(10) 26(3) 235„ ^s_231№ 18<г) 5.7(6) 67(7) 100(10) 28(3) 237 _fe_237 и % - 4.0(4) 65(7) 100(10) 24(3) 2"Np J^233Pe 20(2) 5.8(6) 75.3(80) 100(10) •;9.7(20) г39нр Х-г»Ра 27(3) 5.6(6) 77.4(80) 100(10) 21.9(22) 238^ *-гэ40 39(4) 5.7(6) 71.9(72) 100(10) 23.2(23) 239^ Д.235т„ •- 3.3(3) 66(7) 100(10) 26.7(27) г+г^^гзвц 41(4) 5.6(6) 71.6(72) 100(10) 24.5(25) 241ta ^.2Э7Ир 30(3) 3-2(3) 63(6) 100(10) 20(2) г42тАв—242Аш 32(3) 3.6(4) 73(7) 100(10) 24(3) 2-3Ат Д-г*>„р 40(4) 7.3(7) 84(8) 100(10) 23(2) Юць-Ь-Юс* - 16(2) 149(15) 100(10) 22(2) 242Ст ^.236^ 30(3) 4.9(5) 66(7) 100(10) 23(3) 243^ .=^239^ 51(5) 10.7(11) 79(8) 100(10) 30(3) 244,^ ^w.240^ 27(3) 5.?(5) 72(7) 100(10) 22.4(23) 245Ст ^.241^ 27(3) 6.9(7) 66.(7) 100(10) 34.4(35) 249 JL_249 вк 0f - 11.6(12) 119(12) 100(10) 15.5(16) 250 _JL250 Bk cf - 6.0(6) 87(9) 100(10) 21(2) 249cf -^2450ш 46.7(50) 6.6(7) 76.2(80) 100(10) 23.8(20) 2520f 3~г4вСш 33(3) 3.0(3) 70(7) 100(10) 21(2) 253^ -S4_249 „. № 29(3) _ 100(10) 26(3) 254^ -^-250^ - 6.0(6) 87(9) 100(10) 21(2) 138 Si(Li)-detector of БДРК-2-25 type was applied as detecting block. For ar rangement and hard fixation of X-radiation aource the use Is made of a vacuum chamber in fzont of berillium window of detecting block* The spectrometer is also composed of the сэс2-оз electronic block and multichannel pulee analy- zator of IN-45 type. The detection efficiency was determined by' a set of standard spectromet ry gemma-sources. Apparatus spectra of X-ray for M-, L-series of actinide iвоtopeв are pre sented in £\J. Most obtained data are in agreement with published results within the errors /27. The Table shows that the relative intensities of various elements changed within high limits. It can be caused by such factors as type and energy of exitation, the effects of selective excitation and absorption* References 1. Popov Yu.S. Katalog spectrov M-t L-rentgenovskogo izlucheniya actini'dov. NIIAR-17 (629). Dimitrovgrad, 19u4. 2. Chechev B.P., Kus'menko И.К., Serge9v V.O., Artamonova K.P. Ocenennye znacheniya yademo-fizicheakikh kharakteriatik transura- novykh radionuklidov: Spravochnik. M.: Energoatomlzdat, 1988. 139 THE fERIODIC STABILITY OF THE BINARY INTERMETALLIC COMPOUNOS Of 4-7 THE ACTINIDES B. Elchler and H. Rossbach, Central Institute for Nuclear Research Rossendorf, BOR The demonstration oi these periodicity want a comprehensive presenta tion of the binary systems of the actinides with all the other metals. The available experimental and calculated data are for that not suffi cient. This problem can only be solved using several simplifications. As a measure of the atability is considered the enthalpy of formation of the solid intermetellic compounds. Using the seraiempiric Miedema - model /17 the enthalpies of formation are calculated as a function of the density of electrons» the electronegativity and a hybridisation term. The parameters of the electronegativity of actinides were esti mated from empiric correlations with the electron densities of the di-, tri- and polyvalent metals ftj• The densities,of electrons at the boundary of the Wigner-5eitz-atoiiiic-cellB (nws) of the pure actinide metals were calculated as e funktion of the fflolarvolum e (V), ATOMIC VEKHT (A), the nearest neighbour atomic distance (d) and of the crystal entropies CSnoni(egn п.* » 6,3874-lO-'N^d-V-^A-1'2 exp (7,03 - 5nonnflS s \ WS L 3R N. and R are the Avogadro constant and the gas constant. The values of the crystal entropies were taken from tables for the standard entropies and for calculated values of the magnetic entropies (f(J)). The values foe (d) were found in literature data for lattice parameters or metallic radii. The results of the calcu lations were compared with 330 experimental literature values from 74 binary systems. 75 % of the results were in agreement in a range of - 20 kJ mole'1 and 90 % in a range of - 30 kJ mole'1. In 99 % of the combinations were found the correct signs. For example in fig. 1 the periodicity is shown for intermetallics of divalent Einsteinium. In the case af s- or p- metals the stability of the intermetallics is increasing with the number of valence electrons. A minimum of stability is observed in the 5. end 6. group of the tf metals, Nb, Та, Mo, and Ы ere suitable materials for handling of Es. Shell effects which are appeared in a small stability can observed in systems with Cu, Ag, Zn, Cd, and Hg. An increase of the formation enthalpies in systems witb a d- metal is expected, when this metal is able to fill the d- level in contact with a partner metal. EINSTEINIUM Ros"n5 Ч&* "fait »ui" i» S ? / «< ? П 20 » U SO Ш 60 90 DO Calculated values of the formation enthalpies of the binary intermetallic aquimolar compounds of Einsteinium as a function of the atomic number of the partner metal CM) On the base of these calculations can be predicted the probability of the formation of intermetallic comounds in 1170 b'rrary systems with ell actinides. In nearly 600 systems is to count Kith the formation of least one intermetallic compound. The knowledge of the periodicity permits a critical assessment of particular results by comparison in the groups and in the periods of the periodic system. References 1 A.K. Niessen, F.R. de Boer, R. Boom, P.F. de Chatel, N.C.M. Mattena, A.R. Miedema ^Calphad 7 (1) (1983) 51 - 70 2. B. Eichler, S. Hubener, H. Rossbach // ZfK - 560 (1985) 141 COORDISATION СНЯИКТЯУ OP AOTISIDES IN HOLTEN SALTS Yu. A. Barhanel', V. V. Kolln, V. P. Kotlin, A. A. Lumpov. Ehlop:J^ l Radium institute, Leningrad, USSR In recent works foundations have been laid for spectroscopic research of Lsnthanide and actiuide coordination chemistry In molten salt media /V- High-temperature absorption spectra and coordination properties of actlnldea from uranium to curium were studied. One of directions was 5f - 5f spectral intensity analysis resulting in hypersensitivity iden tification for some of trl- and tetravalent actinides. In this paper, the latest progress in high-temperature coordination chemistry of actinides is discussed. In particular, Judd - Ofelt inten sity parameters are given for the first time (with plutoniuni'as an exaeple) for high-temperature aotinlde systems. A sharp spectral intensity lowering on melting of both Pufll^ and (M(Pu)Ol. is characteristic of all the plutonium (IH) transitions /^/, except those in hypersensitive re gion (Pig. 1), especially ^i/2"*""^5/2 Р1»4*0*** 1» /ЗЛ After crys tallization of molten trichloride (as a thin transparent film), its spectrum (bottom curve) becomes typical for solid PuCl- /V* showing process reversibility* Ihe results of Intensity parametrizatlon (Pig. 2 a-d), along with usual interpretation of 12^ changes, indicate the following: a,b) on melting trichlorides, ninefold f-element coordination changes to predominantly sixfold (octahedral) one with a sharp metal - llgand shortening; c,d) both heating (Li - Ha - K)01 melt and increasing outer-sphere cation size lead to shorter An(Ln) - CI distances and to more symmetrical f-element у у M*W •>.ПАв "H% am им innem „•(l Ktt «Л CM 20 Fig. 1. Absorption Pig» 2. Intensity paraaetersOx (X10 cm*) for spectra of Gd(Pu)01« Pu(HI) and Hd(in): a) Sd(Pu)013> b) BdOlj, (Pu;Gd =1:6) e) (Li - Ha - E)C1, d) alkali chlorides at 830 °c 142 environment. Non-monotonous curve character in Fig, 2d reflects partly the secondary periodical trend to al kali metal ionization potential changes. Largely values for Ju(III) In molten salt media (opposite to aqueous solutions) should be noted as well. Interatomic An— CI distance shor tening on heating (Li - Na - K)C1 melt has also been evideneed by en hancing G, 5/2' *5/г—%п **»"- sensitive transitions in the case of Hp(IX) and by rising relatlvlstio nephelauxetlc effect in the case of HP(Y>. Identification and assignment of fine structure^ of J'*—J transitions is a rather diffioult problem for high-temperature systems. Heverths- gig. 3« Absorption spectra of less, vibronic (<5oin0) components of Hp(III) In the region of Hp0201?" and PuOjBia- absorption 'Ig-•'!,-•»—'i« . transition spectra have been detected at I» SOO °0. As to observing stark splitting, Fig. 3 ia of interest where the distance Лс_й (om~ ) between cold and hot maxima represents ap!""?zjmately llgand field strength for Hp(III). It follows from the spectra and calcu- lated energy level diagram in Fig. 3 thatu c-h' !• e. the difference 5 Е(Г1;Г+;Г.) - 8(Гд), represents (conditionally) I+ ground level split ting. The latter reduces progressively on heating CSjHaHpClg elpasolite, on cooling (Li - на - ЮС1 melt, and also (for melts with approximately equal I) falls with decreasing the average outer-sphere cation Lize: Csd^SgNaNpClgXCs - Li)Cl > (Ы - Ha - K)C1. Such a sequence may be characterized es spectrochemioal series of systems (for the same ligand - Cl"). The complex formation of actlnldes (HI, IY, Y) in chloride-fluoride melts has been studied as well. As a result of Pu(m) and Am(III) spectra analysis In (Cs - Na)F melt, the formation of hexafluorocomp- lexes in a liquid phase was for the first time indloated for trivalent actinides. References 1. Barbanel' Yu. A. Coordination chemistry of f-elements in melts. ILsBnorgoatomlzdat, 1985./in Busslan/ 2. Barbanel• Yu. A., Lumpov A. A.//Sadiokhlmla. 1997. T- 29. S. 730. 3. carnall w. 1. et al.//j. Chem. Phys. 1970.Vol.53» P. 2922. 143 SSARCH ИЖ THE ЦНАНШ COMPOUNDS WITH HIGH CORK Р011И I W.Suski, A.Baran. Traeblatowski Institute of Low Temperature *— and structure Research, Polish Academy of Solencee. P.O.Box 937, 50-950 Wroclaw 2, Poland T.ttydlarz. International Laboratory ot High Magnetic fields and Low Temperatures, ul. Proohnlka 95, 53-529 Wroclaw, Poland H.Figlel, J.Opila, K.Turek. Department of Solid State Fhysios, Academy of Mining and Metallurgy, al. Hlckiewicza 30, 30.059 Krakow, Poland The ternary uranium compounds (UTTA1-I2*X* wnere T ^s 3d element) with the ТЬМп12-туре of structure exhibit Interesting physical properties from various types of magnetic ordering (see e.g. /V to heavy fermion behavior (see /27). These materials have been obtained with composition moatly with x • 4 and not exceeding 6. Reoently we have succeeded in obtaining some compounds with iron at the 3d element with x > 6 (UPeaAl.) and with other elements instead of Al (31, Mo). The preliminary results on UFe1(jSi and П7е.дИо2 have been already published /37. It appear* that Is spite of the high content of Iron UFe^^fog is apparently a ferromagnet with relatively low saturation magnetization and low and diffuse Curie point about 255 K* On the contrary, UFe^^l , being a ferromagnet, ex- Dibits considerable saturation magnetization and high Curie point (700 K), the highest one in this family of oompounde including those with rare earths (see e.g. /4/). However, se could not detect any measurable hysteresis and remanenoe. Therefore, In turn, we have examined this compound on the field preoriented sample. In Pig. 1, the magnetization of UPe^Sig at 4.2 К is shown. Ore oan see that this sample demonstrates both the remanenoe and hysteresis, however, the hysteresis loop is vaif narrow. The results of room temperature (RT) are qualitatively similar but exhibit lower magnetization values and narrower hysteresis loop. Contrary to' bulk mmoriented sample in which at 4.2 К one can see a kink in magnetization in field of about 40 kOe, the present curve is smooth and saturated at about 10 kOe. The temperature va riation of magnetization between 4.2 and RT is also smooth. UFegAl^ with lattice parameters a • 0.856 nm and о • 0.492 nm shows traces of other phases, among than probably the pseudoblnary Laves phase U(Pe, Ai)„. The Curie point esfmeted from the "pe Hossbauer studies (380+25 K) /5/ and saturation magnetisation of UFegAl. are much lower then analogous values of UFe103l2 but remanenoe and hysteresis comparable (Fig. 2). The investigations by other complementary methods, as well as on the ma terials with other compositions are In progress. 144 Sla.uJ UFe1QSi2 T = 4.2 К . HIkOe) -10 "5 j 5 10 50 100 15C Fig.1 0 200 400 600 Fig.2 Referenсев 1. Pteaiewicz-Ввк Я., Benin A., Suski w,, Leoiejewicz J. // J. Надо. Hat. 1988. 1. 76-77. 2. Drulis II., Baron A., Stallnakl B., Suski W., Felten K., Steglioh F. , Faolak I.. // Thernochlnica Aota, in the press. I0.3aK.Io07 ADVANCES in the PREPARATION of 4-10 ACTINIDEINTERMETALUC COMPOUNDS J.Larroyue, M.Beauvy Commissariat a f Energie Atomique IRDI/DMECN/DECPU/SPU/SEFCA C.E.N. Cadarache, 13108 cedes France Actinide intermetallic compounds are intensively studied because of their probability to exhibit an heavy fermion behaviour. We have investigated binary systems of uranium, neptunium or plutonium with respectively indium, tin, thallium and lead. The systems are complex and unfortunately not similar from uranium to plutonium. However the cubic compound An M3 with an Au Сиз structure type has been observed in each system studied. The experimental procedures to elaborate the compound An M3 ae a pure single phase have been established and they are reviewed. The synthesis of some new phases especially in the case of neptunium compounds U discussed. The samples are prepared by induction heating end annealed at 800 °C for one week. They are characterized by X-ray diffraction and metallography (optics, SEM, electron microprobe). Some properties of the ratermetalltc compounds have been measured and are reported. 146 CHEMICAL DIFFUSION KINETIC AND THERMODYNAMIC IN BINARY I 4-11 AND MULTICOMPONENT SYSTEM OF ACTINIDES AND TRANSITION UEfSAJS~ ' Yu.A.Jhevchuk, E.A.Smirnov, G.B.Fedorov. Moscow Engineering Physics Institute, Moscow, USSR The results of chemical diffueion CD investigations,tracer diffu sion TD of components and thermodynamic properties of BCC uranium allo- ув with anomalous transition metals-titanium and zirconium are presen ted. TD of components in alloys was investigated by Grusin'a method. Electron microprobe analysis was used for the CD investigations in bi nary and multicomponent alloys.Calculations of Interdiffusion coeffici ents were made using the Hatano Bolzmaa method and digital computer. Thermodynamic properties of binary system were determined from CD and TD data and Darken equation and compared with that determined ealier by SUP -method«Results of CD investigations in the uranium based systems with the data [l J and with results obtained in the plutonlum based al loys £2|3]&гп analieing in preBent paper. The analysis of data gives that CD and Л In the uranium and Pluto nium based systems show an anomaously high diffuaivity and anomaoualy low diffueion parametera.Concentration dependenses of Interdiffusion coefficients in uranium based systems do not correlate with temperatu res of solidus.Diffusivity of alloys with more uranium content (Fig.) is displaced to the gap,corresponding to diffusivity in normal BCC metals.Such type of dependence agrees with concentration dependen ce of elastic modul in investigated binary systems and corresponds to the change of anomality with elastic lattice distortion energy at the 'elementary diffusion act in the BCC struotures.The results of CD in vestigation la ternary uranlam- titanium-zirconium system snow that diagonal coefficients are larger than that for nondiagonal.Hondlagonal coefficients are small and negative (titanium were made for the sol vent). Concentration dependence of diagonal coefficients ieolinee agrees with Darken*s theory extended on the севе of multicomponeut systems.The component diffusivitlea disoribed by the diagonal inter- diffusion coefficients are also anomaouely high in the ternary sys tem. 147 v \ \ \ \' I-УЗ \—-4X\ x > tt V tf Ц iS %/ Temperature Dependences of Chemical niffueioni 1-"anomal." transition netslsi 2-5 -alloys of uraciun-titenium syatemC 10,20,30,40 at.* of uranium); 6-Byetems of "noreal" transition metals References I.Vedorov O.B. .Smiraov B.A. // Diffusion in Reactor Materials. New Delhi- Calcutta: Oxonian Press, 1984.170р. 2.Reay C. ,Dupuy a. .Calais D. Diffusion ehinique at effect Kirken- dall dans la phase eubique centre» du ayateme plutonium-zirconlu. //J.Hucl.aat.1970. Vol.34, H 1.P.46-58. 3» Dupuy M.fCalais D» Diffusion dans le eyateme plutonium-uranium// net. Sclent, rev. metallurgie.1965. Vol.62, H 10. P.721-732. 148 MAGNETIC PROPERTIES OP THE u _ Th Mn Si2 A№ U The intermetalUc compounds RT?Xa CR 1в з rare earth or actinide element, T is ц nd transition metal and X Is Si or Qe3, which crystallize with the body centred ThCr_Sl2 type structure, have attracted considerable interest in the last decade owing to their wide variety of physical properties ИЗ. The UT23(2 compounds, where T Is 3d metal, order ferro— or antiferro- magneticaUy at low temperatures. For example UMn-Si- is a ferromagnet below 377 К £21. In the case of UFejSi- down to 0.2 К no magnetic ordering was observed 13]. Among ThT-X» compounds only for T * Hn the antiferromagnetic order is observed 14]. The presented abstract describes the results of X-ray diffraction and magnetometrlc measurements made on the S svstems The U._ Th Mn_SI2 and IKMn P*X^2 *2 - purpose of this work is to observe; -firstly, changes of magnetic properties resulting from substitution of U for Th, -secondly, influence of 3d metals configuration on change of magnetic properties, modyfied by substitution of Mn atome for Fe. The detailed procedure for sample preparation is given in ref. E2J. The X-ray diffraction powder analysts show that all samples have the tetragonal ThCr^si -type structure, л least-square fit to the observed 26 values was used to obtain the lattice parameters. Substitution of U for Th atoms leads to linear increase or the a and с constants. This may be attributed to the fact, that the Th atoms have larger atomic radii than U. Tor second system the a lattice constants Increase while the с ones decrease with increasing x. The Fe atoms have smaller atomic radii than Mn. Such dependence of lattice constants with changes of 3d atoms The magnetometrlc measurements were carried out in the temperature range of 80-600 К using an electronic balance. In the U. Tn«MnaSi2 system two concentration regions appear; -for x £ 0.4 the samples have ferromagnetic properties; -for x a 0.6 the samples are antifei-ramegnetlc. 14» Neutron diffraction measurements indicate that in the cast» of UMn^Si2 compounds the ferromagnetic order of the magnetic moments localized on U and Mn atoms is observed below T* 80 K. Above this temperature ferromagnetic structure with magnetic moments localised on Mn atoms Is detected. For compounds with x £ 0.4 the Curie temperature corresponding to the paramagnetic phase transition In U-sublattic* increases up to 150 K, whereas T of Mn-sublattica up to 340 К fop increasing x. ThMn^Si* Is а соШпеаг antlferromagnet below 483 К with the magnetic moment localized only on Mn atoms. Tn Mn Si Por K°i.v 2 2 system the values of Neat temperature increase^ with increasing Th content starting from TH » 380 К for к - 0.6. S In the ease of U u References 1. J. Leciejewi z and A. Szytulra, Unlversltas JageUonica Acta Se.,Lfterumque, Schadee Physicae, Pasdullus 2o ISO MAGSiTIC AHD TRAHSPORT PROPERTIES OP THE PHASES OT^^, j 4-13 I WHERE T • N1, Ou, Pt AMD U • Pd, An OR Al, Be I ' 1 R.Troo, V.H.Tran, Z.Zolnlerelc. Institute For low Temperature and Structure Research, Polish Academy of Sciences, $0-950 Wroclaw, Poland This paper deals with the gystematlos In the magnetic and transport pro m perties of intermetalllc oompounda of the formula $,J*x' where T ie N1, Cu, Pt and a la Pd, Au or Al, Be. The compounds with M » Pd and Au crystal lize In the cubic AuBeE-type orystal structure In which uranium atoms are situated on a fco lattioe with the tf-Udistanc e being larger than 5.0 A. The refore 5f-5f overlap la no longer a major factor Influencing the magnetic behaviour due to the derealization of the 5f states. Hence, the hybridizat ion between the f-d and/or f-в states plays the fundamental role in the mag netic properties observed for these phases. A similar situation one should also expect for ouch compounds, but with И • Al, Be, despite the different crystal otructureB found for UCu.Be and UOu.Al. For the former this structure is still unknown and for the latter compound this adopts the hexagonal CsCu_- type. Previously, we have investigated the effect of the replacement of Cu by Pd in UCUc /V» It was shown that with increasing Fd-ooncentratlon the antifeiw «magnetic transition occurring in UCu- (Тц"15Ю rapidly disappears with si multaneous appearance of Kondo-like behaviour. Contrastingly, the Au-substi- tutlon in UCUg leads to an enhancing the antiferromagnetio coupling between the uranium momenta, as inferred from almost double increase in T«-value. A slight Increase in T^ (up to 18K) has also been reported for VCu.Ag [2j. together with cm enhancement of the low temporature electronic epeoif ic heat coefficient, у 340 mJ/K2 mole at 1.4 E. Another Interesting examples of such a substitution are the systems UPte_z(Pd, Au)z /3/. It is remarkable that the results of magnetic and elect rical measurements performed on these systems exhibit a broad cross-over from the spin fluctuation behaviour, characteristic of OPtj, through heavy-fermlon state In UPt.Au ( fm 725 mJ/E2 mole) /4,57 to Xondo-lattice-llke evidences in the Au-rioh phases CiJ• A similar investigation on so alloyed systems has been performed by Quitmann et al. /5,67. The results obtained by these authove have been discussed using a modified Anderson-model. The antiferromagnetlc ordering of the uranium magnetic momenta In tTOn^Au has rencently been confirmed by neutron diffraction measurements /7/. The main changes in the magnetie and transport properties Qauaed by replacement of Cu by Au In UCue are as follows: as the Au content increases, Ти after going by maximum at X • 1 falls down to 14 К for the sample with x • 2. The oomposlt- ion UCugAu^ becomes paramagnetic down to 4.2 K. At the same time both the magnetic eusoeptibility at 4.2 К and effeotlve magnetic moment values in crease with Increasing Au-oontent. Simultaneously the Kondo-lattice behaviour changes to pure Kondo state as one can deduce from the temperature dependence of the electrical resistivity, measured for the samples with different x.Such a behaviour may be a good example of the competition between RKKX-type inter action and the Kondo effect. Ахл In turn, we have investigated the magnetio properties of the UNic х х eyatem. Previously, the results of magnetic and electrical measurements for a 151 similar system, namely Wiq.x&tx* bave been reported laj. Acoordlng to tbe magnetic properties of the Ni-ricn compositions in the latter system, also UHi.Au behaves as the temperature Independent peramognet. However, for more Au-rich phases, like UNi»Au2 and UKipAUq, a typioal temperature-dependent paramagnetism with the effective magnetic moment of uranium higher than 3 f*fc has been observed. As already mentioned above the UCUc _M_ phases with u being Be or Al are not longer cubic. The magnetisation studies performed for TJCu.Be and UCu.Al at 4,2 К show a stright-llne behaviour up to 5 I. The magnetic susceptibility for UCu.Se follows the exact Curie-Weiss lew above about 15 К with the effec tive magnetic moment of 3*44 M-j, while the reciprocal magnetic susceptibi lity of UCu.Al is oorvelinear, as for all the remaining HIV ^H, phases stu died Moreover, a maximum in the susceptibility observed for this compound at 14,5 К is presumably associated with the transition into an antlferromae- netio state. All the physical properties exhibited by the IT- JIX phases described above are finally discused in the framework of ohangee in the electronic etruoture of the uranium atoms in these phases. References 1. Zolnlerek Z., Troc H., Xaozorowskl D. // J. Hagn. Magn. Mat. 1987. N 63/64. P. 184. 2. Ott H.R., Rudiger H., Pelder S., Flak Z., Batlogg B. // Phye. Rev. Lett. 1985. Vol. 55. P. 1595. 3. Troc R., Tran 7.H. // J. Magn. Btagn. Mat. 1988. IT 76/77 (in press). 4. Ott H." , Rudiger H., Pelder B., Flak Z., Thomson J.D. // Phys. Rev. 1987. Vol. ВЭ5. P. 1452. 5. Qultmann c., Andraka B., Kim J.3., Treadway B., Frauenberger G,, Ste wart G.R. // Pays. Rev. 1988. Vol. ВЭ8. P. 6432. 6. Quitmann C, Andraka B*, Kim J.S., Treadway В., Frauenberger G., Stee- wart G.R., Stioht J. // J. Magn. Magn. Mat. 1988. И 76777 (in press). 7. Quezel S., Troc R., Tran V.B. to be published. 8. van Call H.J., Bushow K.H.J., van Aken P.B., van Maaren H.H.//Phys. Rev. Lett. 1975. Vol.34. P.1457. 152 STRUCTURAL, MAGNETIC AND TRANSPORT PROPERTIES j 4_14 OP TERNARY U - (Cu, Ni, Pd) - (Pt Ae) PHASES D.Kaczorowski, R.Troc, Institute for Low Temperature and Structure Research, Polish Academy of Sciences, 50-950 Wroclaw. Poland We summarize here the results of detailed orystallograph!e, magnetic, neutron diffraction and electrical Investigations of the ternaries occurring in the U - (Cu, N1, Pd) - (P, As) systems. A single-crystal X-ray refinement has shown that most of the compounds studied, namelyi UCuAs», UNiASg, UFdAe2, UCuPg, U^Cu.P-, adopt the tetragonal structures of new types closely related to one another /l,2»37. Neutron dif fraction experiments have confirmed the tetragonal structure of the ThCr£Slg- type for UNlgP^ /4/. The crystal structure of the tetragonal ternarj arsenide UpCu.Ay,. (with uncertain composition) has not been established as yet. The remaining compounds investigated, i.e. UCUgPg and UCu-Asg, crystallize in hexagonal system- However, the crystal structure la known only for the former one4 being of the CaAlgSig-type /5Л Magnetizatlon and magnetic susceptibility measurements oarried out In the temperature range 4*2-1000 К on both powder and single-crystalline samples an for UPdAs2 /"67. As a rule, the uranium ordered moments in all the above pnic- tides are always aligned along the crystallographlc o-axis. The transport properties of UCugPg, UCuAsg, UCuPg and U.CUjP- were studied on single-crystalline specimens within the temperature range 4.2-300 Б. The temperature variation of the electrical resistivity, p(T),for the first three compounds is characteristic of many other semimetallio aotinlde ferro— magnets, i.e. the sharp rise of the resistivity at low temperatures being followed by either a tendency to saturation in the room temperature region (UCuPg and UCu2P2) or by Its slight decrease (UCugPg) or by its slight dec rease (UCuAe2). Moreover the Pisher-Langer type anomalies have been found on the df/dT (T) curves for the above phases. The shape of the J>(T) function observed for the antiferromagnat U.Cu.P„ is more complex, especially below Tjj where it is dominated by a very pronounced resistivity bump. The transversal magnetoresistlvity, Др. , measured for the TJCuAsg ferro- 153 magnet Is negative with the exception of the low temperature region. 1л ad dition, the Apt References 1. Stepien-Dajmii J., Kaozorowakl D., Troc R. // J. Less-Common Met. 1987. Vol. 182. P. 15. 2. Hoel H., ZoJaierek z., Kaozorowaki D., Troc R. // J. Less-Common Met. 1987. Vol. 132. P. 327. 3. HoSl Я,, Zolnlerek Z., Kaczorowakl D., Troc R., Stepien-Damm J. // J. Lese- Common Met. 1987. Vol. 135. P. 61. 4. Piaoher P., Huraalk A., Kaezoroweki D., Troc R. // Physic a B. 1989. 5. Zolnierek Z,, HoSl в., Kaczorowski D. // J. LesB-Coumon Met. 1987. Vol. 128. P. 265. 6. Fischer P., Huraslk A., Kaozorowski D., to be published. 7. Harkowakl P.J.» Kaczorowski D., to he published. 154 INTERACTION BETWEEN FOUR-VALENCE ACTINIDES DOUBLE CHLORIDES 4-15 AMD METALLIC ALUMINIUM H.H.Abdunnabi, Tajura Nuclear Research Centre, Таjura, Libya A.V.Ananyev. Institute of Physical Chemistry of the Academy of Sciences of the USSR. Moscow, USSR Several actiniae elements have been studied for the preparation of their intermetallic compounds and alloys* The Interaction between four-valence uranium, neptunium, plutonlum double chlorides end metallic aluminium have been carried out using salts of CegA&Clg - type. It was proved that several compositions take place for the formation of intexmetallic compounds at a temperature of 600-900*С under the argon atmosphere. Such intermetallic compounds and alloys have composition of AnAlg, AnAl,, АлАДд, AnAl.+Al. The Interactions have been carried out according to the following chemical reaction; AnA1 + 2CBC1 + Cs^Clg + (n+4Ml—— n ^MtaClf, where: An = U, Np, Pu n = 2, 3, 4. The material of CsgAnClg and metallic aluminium powder in the stoichiometric ratio have been compacted and tabletted in a form of pellets. The pellets are then alloyed in a molten salt of cryolite using -АЗ.9О3 crucible. The reaction product was either crystalline powder or a compacted ingot depending on the temperature and aluminium content. Chemical analysis and X-ray diffraction techniques have been eontucted for the identification of the phases of the interne tallies and alloys* On the basis of the presented results we propose a new method for the preparation of the internetallio oompounds and alloys of uranium, neptunium, and plutonlum with a certain composition. 155 IIETAMAGKETXSM IH NOHSTOIOHIOIIBTKIC UAlCo ООВРОШГО | 4_l6 A, V. Andreev. Ural State University, Sverdlovsk, USSR U» hexagonal lntermetallic compound UAICo la a highly anisotropic uniax ial ferromagnet at magnetic fields H^1 Ш/в /1/. The magnetic moment of this compound (due to only uranium atoms) at H«0 Is equal to zero. In /1/ we proposed antiferromsenetlo ground state of UAICo, as It is In related com pound UA1F1, whioh also undergoes metamagnetic phase transition (with one or der higher critical field Hop a 9 MA/m). However toe further investigations show the аЪвепае of any anomalies in temperature dependences of resistivity and heat capacity, observed at magnetic ordering In UA1N1 and other magneti cally ordered OXT compounds /2/. So the metamagnetlc phase transition Into ferromagnetic state, apparently, goes from paramagnetic state, and UAICo may he the first hand Sf-metamagnet. Щ this contribution the magnetic properties dependence on deviation of composition from exact atolohiometry 1i1:1 are studied. As it was found, a honogenity region is Burprisely wide, solid solutions of replacement Ux(AlCo)(, _Tw2 with ZrKlAl type structure exist within 0.8 sx £1,2 (from и0.8А11.1°°1И to u1.2Al0.9Co0.9) field of transition Into ferromagnetic state h*e decreases with the decreas ing of uranium content. And there is already a ferromagnetic component In zero field at x£0.9. The magnetic properties versus the uranium concentrat ion x are shown in Fig. 2. Curie temperature T0 of high-field phase is almost compositionally independent (16-18 K) and approximately equal to T- of spon taneous ferromagnetio phase (15-16 K). When uranium content is constant rep lacement of Co by Al (UA1, Q-Co0 qc' decreases ft and increases H . When opposite replacement take plaoe (UAl0_0cOo1 Q.) u Increases and ferromag netic component appears. Strong dependence of Her on composition and the wide possibility of replacement of different atoms explain a big field Interval of metamagnetlc transition, because there are uranium atoms with different local neighbourhood and so with different Hgr even at fixed average composit ion. The results are disoussed in comparison with band 3d-metamagnets LutCo^^Alj^ /3/ and uranium metamagnets with antiferromagnetlc ground state from UAl^^OajjBl - system /4/. 1S6 Referenoes 1. Andreev Л.V., Lavltin R.Z., Popov Yu. P. et al. // Soviet Solid State Phy- eics. 1985. Vol. 27, H 6. P. 1902-1904 (In Russian). 2. Sechovaky Т., Havela b., De Boer ?.B. et el. // Phyeioa B. 1986. Vol. 142. F. 283-293. 3. Gabelko I.L., Levltin R.Z., «tarkoeslan A.S. et el. // Soviet Physics JETP Letters. 1967. Vol. 45. N 7. P. 360-362 (In Rueeian). 4. SecnovBlor V., Maletta H., Bevels L. et al. // J. Appl. Phye. 1988. Vol. 63. N 8. P. 3067-3069. 1S7 MAGNETIC PROPERTIES OF UAs-YAs AND UAs-YSe ALLOYS IN HIGH MAGNETIC FIELDS T. Palewski, T. Mydlarz and A. Gllewskl International Laboratory of High Magnetic Fields and Low Temperatures Prochnlk Street 95, 53-529 Wroclaw, Poland Introduction, UAs, YAs and YSe with NaCl-type crystal structure and very close lattice para- meters form UAs-YAs and UAs-YSe solid solutions in the whole range of compositions. Study of UAs in high magnetic field (1) revealed that apart from two antiferromagnetic structures found earlier» there exist two additional ferrlmagnetic structures. The investigation of sol id solutions of UAs with isostructural uranium, thorium and yttrium monoseleiiides or roono- arsenides offers possibility to predict and observe how these antiferromagnetic or ferrimag- netic structures are modified under influence of increasing amounts of second monocompounds or increased magnetic field. So far, magnetic and neutron diffraction measurements were fo cused mainly on UAs-USe (2), UAs-ThAs (3) and UAs-YAs (4) but only the study Of UAs-USe sys tem (2) made it possible to determine the magnetic phase diagram of this solid solution. The magnetic behaviour of UAs-YAs and UAs-YSe alloys {see F1g. 1} showed rather unexpected and diversified changes of the antiferromagnetic properties of this type of solid solutions. It was interesting to check how a high magnetic field influences the magnetic properties of these alloys. Experimental. Samples of (UAs^tYAsJ^and (UAs)x(YSe)1_K solid solutions for x > 0.60 were prepared by melting mixtures of UAs and YAs or YSe in an arc furnace and subsequent an nealing- of solidified solutions at 1000 °C for about 7 days in vacuum. The purity and homo geneity of UAs, YAs, YSe and their alloys were controlled by the X-ray method, standard mag- io_a netic measurements were carried out by the Faraday method over the temperature range 4.2-300 к using В • 0,42 8 T a Cahn electrobalance. -Investigation in high mag Ti.IU, netic fields were carried out in fields up to 15 T by '.mploylng a Bitter-type coil. The de pendence of the magnetization upon the field (UAflbOfAe) 1-ac was also measured in a pulsed field at 4.2 К with induction up to 42 T. Results. The characteristic feature of both solid solutions is the. disappearance of the antiferranagnetic behaviours with increasing amount of yttrium in uranium SLblattice and replacing them by a stronger magnetic ex change between uranium atoms similar to fer- ri- or ferronagnetlc. In the case of (UAs)x(YAs) alloys, the magnetic proper ties of the samples with x >0.S5 are close to those of pure UAs . In external'magnetic fields up to 10 T,. the low-temperature mag netism is characteristic of antiferromag- Fig.l.The therraomagnetlc curves of solid so netics, the Heel temperature decreasing from lutions of (UAs)x(YAs),_x and (UAs)x(YSeh-x 127 to 105 K. Investigations of these alloys in a constant magnetic field. at high magnetic field up to 36 T in pulsed magnet confirmed the existence of only one tran sition magnetic. Properties of alloys with 0.60 <: x < 0.85 suggest the existence of ferri- magnetic ordering which is destroyed at T = 60 i 90 К whereas his teres is loops are disappear at T = 25 *30 к. Studies of (UAs) (YSe) alloys for x > 0.85 showed that their magnetic behaviour is similar to that in UAs-YAs alloys in the same range of composition. However, measurements of the dependence of magnetization on magnetic field at 4.2 К carried out em ploying pulsed magnet with maximum induction to 42 T (see Fig. 2) revealed the existence of two jumps: the first at 10 т12 Т, similar to that found in UAs-YAs alloys, and the second, in field, higher than 20 T, probably reflecting the transition to ferromagnetic ordering, when the amount of yttrium selenlde increases above 1 -x > 0.15 , the former jump disappears whereas the latter shifts to significantly lower magnetic fields. On the other hand* in mag netic field not exceeding 5 T, the antiferromagnetic structures are stable in UAs-YSe alloys for concentrations of yttrium up to 35 % of YSe» i.e. concentrations higher than in the case of UAs-YAs alloys where 20 % of YAs completely destabilizes the antiferromagnetism. Final conclusions , Addition of yttrium atoms in different chemical forms (as YAs or YSe) to (UAs^CYSe)^ uranium sublattice in UAs modifies dramatically (but in different way) magnetic behaviour of UAs-YAs and UAs-YSe alloys. Replacing uranium atoms by yttrium favours a ferromagnetic ex change between uranium atoms in diluted UAs al loys. For the solid solutions (Wte)K(*B) , where В = As or Se. in the composition range x & 0.60 , typical effects connected with dia- magnetic dilution have not been observed. Irfffpr^T" ,—>_—„—ц__ 40 ВШ Fig. 2. The field dependence of the magne tization of (UAs)j,(YSe)i_x solid solution for x = 0.90, 0.85, 0.80 and 0.70 in a pulsed magnetic field References J. Rossat-Mignod, 9. Bur let, 5. Quezel, 0. Vogt and H. Bartholin // Crystalline Electric Field Effects in f-Electron Magnetism (Proc, 4th Int. Conf., Wroclaw, Poland, 1981), R.P. Quertin, W. Suski and Z. Zolnierek, eds. (Plenum, New York 1332) p. 501. H. Kuznietz, P. Burlet. J. Rossat-Hignod and 0. Vogt//J- Kagn. Magn. Hat., 69 (1987) 12. 0. Vogt and н. Bartholin^. Magn. Magn. Hat.» 15-18 (1980) 531. T. Palewski and T. Mydlarz, Physica B, in press. 159 FISSION ПЦКМЕМГ DAUGE OF МХМЕПС URANIUM COMPOUNDS 4-18 H. Matsul, И. Tbmaki, U. Horlkl and T. Kirihara Department of Nuclear Engineering, Nagoya. University, Nagoya, Japan In order to understand the chemical bonding and electronic structure of the actinides, there nave been a lot of studies on the magnetic and truisport properties of various uran ium compounds. However, scarce study has teen carried out on effect of radiation damage on the physical properties of the actlnlde confounds. Only the self-damage by a-particles of sponteneous fission has been investigated so far on uranium and plutonlum oxides. Radi ation damage, especially fission fragment damage caused by fission of 'V-235", is important to predict the nuclear fuel performance in fission rector. In this context, we have been long investigating the effect of the fission damage on advanced ceramic nuclear fuels (UC and UN tlj) from a fundamental point of view. Since a discovery of significant changes in the magnetic properties of an antiferromagnetic UN <т^=52 K) (zl with fission damage, we have continued the study on other magnetic uranium сопрсолбя. In the present paper, we sumarize our results obtained in a decade on fission damage in seine magnetic uranium comp ounds, mainly with the N&Cl-type crystal structure, as shown in Pig. 1 Magnetism of Uranium Compounds Compound Crystal Ultice Hagtielic Hane Structure Parameter Transition (1С fcc(NaC)) a, .0.4961 para a-UCi bet UN fcc(NaCl) а.-0.48Ю U-- 53.1 К UP fcc(HaCI) a--0.5589 TN-iza.2 R ~Ш Ж** зоб cub a„=0.808a TV 57.I K TEMPERATURE, Т/К a-= 1.0684 a-U,Na cub TH^= 52 К UOz fcc(CaFa) a.=0.G47) T„= 32.1 X Fig. 1. Temperature Dependence of Magnetic Susceptibility of Some Uranium Compounds US fcc(NaCl) ae-Q.5488 Tc=180.Q К Studied in the Present Investigation hex Post-irradiation examinations were performed by measuring the magnetic and electronic properties at low temperature, together with the lattice parameter at roan temperature. The neutron irradiations were done at room temperature within rather a light fission dose range < «lO33 fissions/fflp), because of avoiding radiation effects due to secondary induced complex defects. Isochronal annealings up to 1200 К were carried out to examine the chara cter of the induced 160 zatlon was observed in measurements at low magnetic 1 field (less than 0.1 Tesla) in 'Ъего-field cooling" procedure» Othpr magnetic parameters (i.e., the magnetic transition points, either TM andTc> varied with fission damage, being well consistent to the _ So change of electrical resistivity. The so-called ^characteristic temperatures" in UP [7] and 0-U2H3 J*9 <• UN (AF) [8] were also shifted by fission damage. In addition, / * UP (AF) ? fission induced defects resulted in lattice expansion *» US in all compounds. In Fig. 2f shifts of TN and Tc to lower temperatures are illustrated as a function of ДаУа. increased lattice parameter for the compounds with Fig Decrease of Magnetic NaCl-type structure». It is of interest that a linear Transition Points (T and relation is observed between the decrease of magnetic H T > due to Induced Lattice transition paints and the induced lattice expansion, c Expansion in UN, UP (AF) indicating that the spacing of the nearest U-U atoms and US (F) is important in the changes of magnetic properties, hence the change in the electronic structure, of uranium compounds. All the induced changes In the magnetic property by fission damage were completely J Л г.4х!0" f/m recovered in Isochronal annealing up to 1200 K. I As one of our new results, it is represented In U l.lxlO22 f/m3 Fig. 3 that irradiated U0_ reveals a quite strange magnetic transition (at about 15 K) which changes the position with fission dose. It is noticed here that, U0 Non-Irradiated in contrast to other compounds, Т., of Ш„ shifted to 2 higher temperatures with fission damage. Similar to 0 20 40 60 80 and a-UV ( M K)l fl eared in UP A2 V PP HJ and B-UgNg TEMPERATURE, T/K respectivelyitively, with high fission damage ( >1023 f/n?), even at low temperature irradiations. In those comp Fig. 3, Magnetic Susceptibility of U0» with Fission Damage: ounds, the magnetic transition points shifted to A new magnetically ordered higher temperatures than the original (non-irradiated). phase is found at about 15 К 1. K.thtsui, M.HorUtl, M.Tamdtl and T.Klrlhara: AS1M 5IP-956 (1S87) 59Э. 2. M.Tamkl, A.0hnukl, H.Matsui, CMatsunoto and TJUrihara: Physlca 102B (1980) 258. 3. M.Tairaki, H.Uatsui, A.0hnuki, G.lfatsumoto and T.Kirlhara: Bad. Effects Stt (1985) 81. 4. H.tetsui, S.Suzuki, K.Nakaya and H.Horlki: Inorg. Cnim. Acta 140 (1987) 173. S. H.ttitsul, K.Katort, M.Tamakl and T.Kirlhara: J. Less-Conn. Metals 121 (1986) 307. 6. H.Hbtsui, S.Suzuki and M.Taraikl: J. Ifeg. Ifag. Ibter. 70 (1987) 400. 7, H.Matsul: Phys. Stat. Sol. (a) 101 (1987) 825. 8. H.Mitsui, S.Suzuki and H.Tarokl: Phys. Stat. Sol. (a) 103 (1987) 199. П.Зак.1607 THE EFFECT OF FISSION PRODUCT ELEMENTS DISSOLVED i i IH (U,Pu)C OH THE THERMAL CONDUCTIVITY. ' ' X.Arai, T.Obuichi, S.Fukushima and M.Handa Japan Atomic Energy Research Institute, Oarai-nachi, Higaahiibaraki-gun, Ibaraki-ksn, 311-13» Japan Introduction Thermal conductivity is one of the most important properties of nuclear fuel. Oraniurn-pintonium mixed carbide is considered aa an advanced fuel for LHFBHs for its high thermal conductivity besides high fissile atom density. Although the thermal conductivity of mixed carbide fuels has been measured for a few decadeв, no comprehensive results about the effect of fission products are obtained. The present study concerns the effect of typical flesion product elements dissolved in (U,Pu)C on the thermal conductivity. Procedure It is known that zirconium, molybdenum and rare earth elements dissolve in the carbide matrix phase to a certain degree during irradiation. In the present study, near-stoichionetric solid solutions of (U,Pu,Zr)C, {U,Pu,Ce)C and (U,Pu,Mo)C containing up to 10 molt for 2rC and CeC, 3 шо13В for MoC were prepared in the glove boxes with purified argon gas. The thermal conductivity was determined from the thermal diffusivity measured by the laser flash method from 680 to 1600 К under a vacuum at a pressure less than 8 x 10"-* Pa. The electrical resistivity of the solid solutions were also measured by the dc four probes method in order to evaluate the electronic contribution to the total thermal conductivity. Results The thermal conductivity decreased with the contents of ZrC, CeC or MoC in the solid solutions. Figure shows the thermal conductivity of the (U,Pu,Zr)C solid solutions as a function of temperature. The thermal conductivity data in Fig. 1 are normalized to 100 XTD (theoretical density) by a porosity correction. On the other hand, the electrical resistivity increased with the contents of ZrC» CeC or MoC contents .in the solid solutions although the temperature dependence did not 162 change significantly. The electronic thermal conductivity calculated from the electrical resistivity predominates for all the present samples ever the temperature range investigated. It was found that the decrease of the thermal conductivity of the solid solutions compared with (U,Pu)C was mainly caused by the decrease of the electronic thermal conductivity, i.e. the increase of the electrical resistivity. 800 1000 (£00 1400 1600 Temperature, К Thermal conductivities of 163 MEASUREMENT OF THE CARBON POTENTIAL OF URANIim-PLUTONIUH MIXED ^ 4-ZO CARBIDE FUEL ВУ GAS EQUILIBRATION P.K.Prakashan, K.Ananthasivan, I.Kaliappan, S.Anthonysamy. P.R.vasudeva Rao and C.K.Mathews Radiochemistry programmer Indira Gandhi Centre for Atomic Research Kalpakkam, Tamil Nadu 603102, India The Fast Breeder Test Reactor (F3TR) in operation at Kalpakkam, India uses a plutonium-rich mixed carbide of uranium and plutonium clad -in stainles steel (316» tubes. Fuel-clad compatibility depends on the relative carbon potential values of the fuel and the clad. The measurement of the carbon potential of the fusl as well as the clad, as a function of temperature, using an electrochemical carbon meter was recently reported from this laboratory. In the present work the carbon potential of the FBTR fuel in the temperature range 986-1168 к was measured by methane / hydrogen gas equilibration technique. A schematic diagram of the experimental apparatus is shown in Fig.l. The apparatus was enclosed in a high purity argon atmosphere ( <2 pom of oxygen and <, 2 ppro moisture ) glove box. The carbide samples were allowed to react with purified hydrogen at the desired temperature and the methane generated was monitored at different time intervals using a flame ionisation detector. Equilibrium was assumed to have been attained when the amount of methane in the reaction chamber remained unchanged for at least 4 hours. The temperature was controlled within +_ 2 К using a proportional temperature controller. The validity of the technique was first verified by measuring the carbon potential of WC-W system and the values obtained were in good agreement with literature values. The carbon potential measurements were carried out on Cr С -Cr С system also using this technique and the results obtained were found to be in good agreement with the data generated in our laboratory based e.m.f. measurements. The values of the carbon potential of the FBTR fuel (composition Pu: 66.72 wt% j U: 27.46 wt» ; C: 4.72 wt* ; 0: 3900 ppm ; N: 72B ppm) measured by this technique are given in table 1 and Fig.2 along with the results obtained by Garg et.al. [1] by an isopiestic technique and by Rajendcan Pillai et.al. (21 by an electrochemical carbon meter. based on the results of the measurement of carbon potential of FBTR fuel pellets, the possibility of clad carburisation can be excluded. 164 Carbon potential of the FBTR fuel Temperature Carbon potential к kJ/mol 986 -72.157 1040 -64.622 1073 -60.957 1123 -55.124 1168 -50.078 H, IN (>OUT ^„..рТОПО T Tg«» f—w 6L0VE BO»]-1 III Fig/,1. Apparatus for Gas Equilibration [SAMPLING FURNACE |P0RT (•QUARTZ (SAMPLE SODIUM BATH [HOLDER Fig.2. carbon potential of the FBTR Fuel ~S5o 5oo Boo 1Ю0 1200 TEMPERATURE (K I <— References 1. S.p. Garg, G.L.Goswamy, R.Prasad, and, D.D.sood (Private communications!. 2. s.Rajendran Pillai, S.Anthonysamy, P.K.Prakashan, R.Ranganathan, P.R.Vasudeva Rao, and C.K.Mathews. J. Nucl. Mater, (under publication) 165 SYNTHESIS OF ACTINIDE PNICTIDES BY SELF PROPAGATING HIGH TEMPERATURE SYNTHESIS I 4.21 Robert G. Behrens and Mary A. King Materials Science and Technology Division Los Alamos National Laboratory Los Alamos, New Mexico 87545 USA Synthesis of compounds between the actinide metals uranium and thorium and the Group Vlb elements (pnictogens) phosphorous, arsenic, and antimony is usually carried out in evacuated sealed tubes at high temperature. However synthesis by condensed phase combustion techniques is feasible, as the enthalpies of formation for most of the uraniunwnd thorium phosphides, arsenides .and antimonides are sufficiently negative to allow initiation and propagation of a self sustaining, high temperature combustion wave in a mixture of the reacting chemical elements. This paper presents results of- our attempt to synthesize actinide pnictides using the Self Propagating High Temperature Synthesis (SHS) technique. Synthesis of these compounds by SHS is characterized by high (>2000 K) adiabatic combustion temperatures and the presence of one highly volatile chemical component (the pnictogen). We will describe the chemistry of these syntheses using data from x-ray powder diffraction, metallographic and electron microprabe analyses. COMBINED XRD. OPTICAL REFLECTIVITY. AND X-RAY „ ABSORPTION eTUDY OF ACTINIDE PNICT IDES AND 4-22 CHALCOGENIDES: A TRIPLE WAY OF APPROACHING 5f BEHAVIOUR UNDER PRESSURE U. Benedict1, S. Dabos-Seignon1-2, L. Gerward3, J.P. Шё4, H. Lao15, J. Staun Olsen6 1 Commission of the European Communities Joint Research Centre Institute for Transuranium Elements Postfach 2340, D 7500 Karlsruhe Federal Republic of Germany " Institut Curie, Physicochimie des Elements Transuraniens, F-75231 Paris л Danmarks Tekniske H0jskole, Laboratoriet for Teknisk Fysik, DK-2800 Lyngby * University Pierre et Marie Curie, Physique des Milieux Tres Condenses, F-75252 Paris * Jilin University, Institute of Atomic and Molecular Physics, Changchun, Jilin, People's Republic of China 6 K0benhavns Universitet, F'ysisk Laboratorium, DK 21OOK0benhav:.0 Actinides and actinide compounds were studied under high pressure by X-ray diffraction, X-ray absorption and optical reflectivity. These studies concentrated on the actinide monopnictides and monochaicogenides. Nearly all с i'them exhibit structural phase transitions under pressure. A large group, mainly those with anions of medium atomic mass (As, Se, Те), have a CsCl (B2) type high-pressure structure. Sb as an anion favours a tetragonal high- pressure structure, while several other structures were observed for the high- pressure phases of the compounds with N, P and S. The compressibilities were determined for all of the compounds studied. For 10 uranium and thorium compounds, variation of reflectivity with pressure and with the energy of the incident light was measured. Peaks in the reflection spectrum correspond to resonant electronic processes that are excited in the solid by the incident light. Many of these peaks could he correlated with either the high-pressure or the ambient-pressure phases of the compounds studied, supplying indications on the electronic structures of these phases. By determining the Lm X-ray absorption edge of uranium in UC and UP as a function of pressure, it was round that pressure-induced structural phase transitions in these compounds are accompanied by a 1-2 eV shift of this edge. This shift can be explained in terms of increasing derealization of the 5f electrons. REGULARITIES OP PHASE EQUILIBRIA in THE BIHAR* BRARIUM I • -• TETRACHLORIDE SYSTHIS I W.Gawel. Department of Inorganic Chemistry, Hedical Aoadeny, Wroclaw, Poland la it possible to predict a phase diagram of unexamined binary salt eye- tern, when the physico-chemical properties of its components are fcnnwn? The problem has been studied by many investigators since many years, but the question is «till far /тою being answered satisfactorily. Prom the present author' a studies (by thermal analysis and cryometry as main methods) on the phase equilibria of the uranium tetrachloride binary systems, and other data, some conclusions may be drawn, however, that approach a solution of the question* In paper /1? the importance has been shown of cation ionic potentials M. ( rtj - t , where Z, and r^ - valency and radius of cation "1", respecti vely, e - elementary charge) for phase equilibria in binary MCJ^-UCl, sys tems (M - any metal). Aa it appeared, the type of phase diagram of a system depended closely on the ratio of ionic potentials of both component cations 1 e t t The f^/Pg» " * ^l&^*/|\|'^*• dependence is quite visible when all the MCln- UC1. systems, the phase diagrams of which are determined up to now, we ar range in order of decreasing (^/Цр.valuea > ao in Table. The Table embodies also the recent, still unpublished, author's data on the systems InCl.-UCl, /5/ and InCl-UCl. /3/. The systems in the Table may be divided into several groups. Each of them oemprises a separate type of system. As it may be seen, when the f^/po ra*io exceeds any definite critical value, a stepwise change occurs of the type of phase equllibriai simple eutectio systems (I1) - sys tems with continuous solid solutions (0) - simple eutectio systems again (I) - one chemical compound (II) - four compounds (III), It is surprising that from II to III group of the Table there is no gradual transition through the systems with two and then three compounds. Henoe we can come to a conclusion that there are no suoh a binary systems containing UC1. aa one component, in which two or three compounds are formed. The conclusion has been proved /3/. + When р./|*2 к 1, the electric field intensities of cations U* and Up* are identical, therefore the interactions of both the cations with chloride anions are similar which results in forming continuous solid solutions ("ze ro group"). As the f*|/(*2Talu e decreases, the ionic potential of tl*+ begins to predominate and the interaction of the cation with CI" is stronger, then the possibility of compound formation la greater. When f^/fj > 1, the chan ges follow the same pattern, but - in this case - due to effect of the first component cation. It should be noted that, in spite of the assumption of only ionic model of salts and the neglect of many other factors affeoting the phase equilib ria, the regularity as above is obeyed by all the binary uranium tetrachlo ride systems independently on both the valency of cations and the character of chemical bond in a molecule of first component £4Z* Applying the Table, we may predict with considerable probability the ев- sentlal features of a system that was not yet studied. The regularity reported here seems to have an universal charaoter in re- Mi Table. Types of Binary uranium tetrachloride ayetome and values of ionic potentials ratio of component cations Group No. PVfS System Type of system I1 1. 1.78 Euteotic 2. 1.5fi Be0l|-U014 Eutectie 3- 1.09 FeCl,-BCl4 Euteotle 0 4. 0.95 Th014-D014 Coat, solid eolns. I 0.90 ButSOtic 5. inoi3-uoi4 6. Eutootio 0.75 ngci2-irei4 7. 0.70 Batectic Cd012-U014 8. 0.70 Euteotio ba«3-VCl4 9. 0.70 Eutaotle uoi3-uoi4 10. 0.66 2nCl2-0Cl4 Euteotle 11. 0.49 CaCl2-OCl4 Eutoctle 12. 0.44 Hgoi2-noi4 Euteotlo 13. 0.43 Sr012-U014 Euteotlo iffl i II 14. 0.41 Compound 2:1 15. 0.40 Compound 6:1 16. 0.36 Compound 2:1 17. 0.25 Compound 2:1 IB. 0.25 Compound 2:1 19. 0.19 Compound 2:1 m 20. 0.185 4:1* 2:1 1:1* 1131 21. 0.18 KCI-UOI4 2:1 1:1 1:2* 1:3* 1 22. 0.17 RDCI-UCI4 3H 2:1 1:1 1:3* 1 23. 0.14 СаС1-ПС14 3:1* 2l1 1.2 1»Э* Index "l" at the component molar ratio of respective oompound denotes "incongruently melting*1 latlon to all binary salt systems with oomnon anion, beoause analogous re sults to those represented in Table, «ere obtained also for another salt system families, e.g. HCL-AgCl Д/. References 1. Genet W. // Rocznlkl Cham. 1975. Vol. 49. P. 699. 2. GaweZ w. // Palish J.Chem., to be published. 3. Gawet W. // j,Thermal Anal., to be published. 4. Gawe* W. // Polish 3. Chen. 1983. Vol. 57. P. 391. 169 ELECTROCHEMISTRY OP URAHIUM IN SODIUM | CHLOROALUMINATE MELTS W.D'Oliealager, F.Meuris, L.Heerman. Laboratorium Radiochemie, K.U.Leuven, Celestijnenlaan 200G, B-3030 Heverlee, Belgium The electrochemistry of uranium in sodium chloride saturated chloroaluminate melts indicates that the oxi dation/reduction of the U(VI)-U(IV) couple is an irre versible two-electron process. The comparison of the of the results of solutions of uranium(VI) (prepared by dissolving UO3 in the melt or by exhaustive electrolysis of U(IV) solutions) and of solutions of U(IV) (prepared either by dissolving J02. UCI4 or Cs2UCl6. or by electrolysis of a U(VI) -solution) indicates the existence of two uranium(IV) species in slow equilibrium; only one of these species can be oxidized to uranium(VI). The equilibrium constant for the equilibrium between both U(IV)-species (UUV) ' » U(IV)) can be obtained from the cyclic voltammograms (peak currents), from cou- lometry at constant potential (current—time curves), and from pulspolarograms (limiting currents). K-values obtai ned from these different techniques are mutually in good agreement. EMF measurements of uraniumfVl)-uranium(VI) mixtures result in a fractional value for the number of electrons in the redox equilibrium U(VI) 5==^ U(IV) (Nernst' equation); this observation indicates the existence of a disproportionation reaction 2U(V) ч==ь U(VI) + U(IV) . The equilibrium constant of this process is small (Kn " .34 ± .08). and thus results in a single wave of double height in the pulspolarograms (or a single peak in the cyclic voltammograms), in agreement with the theory. The reduction of both uranium(IV) species leads to the formation of two insoluble uranium(lil) species at the same potential. Stripping of these U(III)-species is shown to occur at different potentials. 170 METAL CLUSTERS WITH REDUCED ТГОКПИ BROMIDES I I 4-25 A.Sincm, F.BBttcher, F.Ueno ' Max-Planck-Institut fur Festitfrperforschung Stuttgart, FBG The structural chemistry of reduced thorium halides closely relates to the situation with the lighter homologue zirconium as well as the neighbouring niobium and tantalum respectively. Cluster compounds are formed which need a stabilization of the electron deficient clusters by interstitial metal or non-metal atoms. The new compounds ThgBr^C, Th^r^ (M = Fe, №1, Co) and ТЦ^Вг.,^ are reported. ThfiBr1,C is isotypic with Zr,Cl14C which has the same kind of metal hallde framework as NbgCl.., but in addition an inter stitial С atom in the center of the Th, octahedron. The metal halide framework of ThgBr.. Jl is isostructural with NbgF15 and thus exhibits unusual linear bromine atom bridges. The Th. octahedra are centered by 3d metal atoms as in similar zr cluster compounds. A novel cluster type is found with the compound Th12Br2gN6 which contains two parallel planar triangular Th, units. N atoms fill the tetrahedral voids between than and the Br atoms surround them. Chemical bonding in these compounds and physical properties are dis cussed. 171 PREPARATION OP HYPOSTOICHIQMETRlC U02-x AT LOW THlPHtATURES i AND STUDY OP SOME PROPERTIES 1 4"26 I.I.Kapahukov, JLV.Icralyuflhkin» L.V.Sudakov, A.S.Beva. Research Institute of Atomic Reactors» Dimitrovgrad, USSR The phase region of UOj.j, is at the temperatures above 1600°C or. the diagran of U-o. The attemps of some investigators to prepare UOj-x ^Y quenching at room temperature proved unsuccessful. In the present study the U02.„ specimens were prep-red by thermal treatment of the sealed zirconium or quartz ampules contained the powered (Ю, and thori um metal having properties of oxygen getter. UO, and Th Were disposed in the form of layers (Th was the above and bottom layer, uo2 - in the middle) and mixtures. After annealing at the temperature 400°C and above the ampules were carefully opened and sampled (1-2 rag) from various regions for X-ray phase analysis. The main results obtained by X-ray analysis of the oxide phase formed from UOj are following! 1. Prior to annealing the starting parameter of the dioxide uranium crys talline lattice was a = 0.54705*0.00003 nm. After annealing the parameter always increased. 2. The lattice parameter begins to increase since the temperature SOD C. 3. The maximum value of the parameter a-. =0,54760 nm is estimated which was achieved at the temperature 1000-110O°C; a further increase of the tempera ture and annealing time do not cause the change of the lattice parameter. 4. oxides with the lattice parameter up to O.S4720 nm are brown and those of O.5472O-0.54760 nm are black in colour. 5. The oxide phase with the increased parameter value after annealing at 1000°C in tAr+5%H2) mixture reverts to the startinn state with the lattice parameter a . In our opinion the results 1-4 evidence the formation of the hypostolchio- metric urania UO,.., and the absence of the (D,Th) oxides formation is proved in 5. in addition for the same ampules subjected to the identical heat treat ment the lattice parameter of the oxide phase of the quenched sample was found to be always higher than that of the slowly cooled sample. Over the ex tended annealing the very weak diffraction lines belonging to o(-U metal were observed on the diffraction patterns of samples selected from the regions of the urania phase. Hence on cooling the ampule from annealing to rcum tempera ture the particular dispropc-rtionation of OOj-x to uranium metal and UOj-x ' x1>x2 is not neglected. To estimate the oxygen coefficient of U02_x a method of solid electrolyte coulometry (SEC) was used [i] . The method allows the oxidation kinetics of ^г-х up to u02 000 to ** observea. Tb* curves of SEC-titration were determi ned to be composed of two peaks (Pig.lb For the identical samples subjected to the same thermal treatment the first peaks of the quenched sample (curve a) is always less than that of the slowly cooled sample (curve b). It is also stated that ti«* oxygen absorption by a sample concerning the first peak does not change the lattice parameter values obtained after quenching, it follows that the first peak characterizes the oxidation of the uranium metal 172 mA f\ 8 ; 800 7 r\ 60C s It б V ' ft 400 20C 5 i i О 20 40 60 t^inln Plga1. Current versus time curves of various types of samples Investigated by SEC a - quenched sample; b - elowly cooled sample 1 1 -T 0.5476 - 4o 0.5474 4C a - 0.5472 . о \ _ 0.5470 \4iь • 1 1 199 2jOC ratio 0/U Pig. 2. lattice parameter versus 0/V for U02_z a - present study; b - line with another elope for W>2+x (e.g. Д/) released as a fine-dispersion phase while cooling the ampules. From the first peak value the content of the uranium metal in the quenched sample nay be es timated ав£1%. The oxidation of uo2_x up to 002>000 is characterized by the second peak. Using the second peak alone the oxygen coefficients of the U02_x samples were estimated and the lattice parameter versus the 0/u ratio was plotted (Fig.2>. Thus in the thermal treatment conditions at the very low oxygen potentials the hypostoichiometrie U02_„ may be prepared at the temperature 500-1200 С and fixed by quenching at the room temperature. The experiment has shown that the lattice parameter of UO2-X coneervea ite value while exposing to air for a long time. Reference 1. «eeke K., Ullmann H«, RetUg B.//J. Bool. Hat. 1983- Vol.116. P.260-266. 173 DEFECT CHEMISTRY Of URANIUM OXIDES , Reiji NAITO, Tosnihide TSOJI and Tsuneo MATSUI | 4-27 j Department of Nuclear Engineering,. Faculty of Engineering, Nagoya University, Furo-chor Chikusa-ku, Nagoya 464-01, japan Uranium oxides are known as nonstoichiometric compounds of which romposition is changed corresponding to the external conditions such as temperature and oxygen partial pressure. The change of composition caused by the formation of defect structure results in the change of their properties. In this paper, the compositional changes of D02 and doped U02 f(U,M)02; №La# Tif Pu< Th, Mb, cr, etc.) and also that of other uranium oxides (U40«, U3Og) are shown against oxygen partial pressure. Prom the results of doped U02, it iB concluded that the valence control rule holds. The defect structures are estimated both from log x vs. log Po2 pressure) and logcf vs. log PQ2 (б*: the electrical conductivity) relations. The defect structures of U02 and doped UO, ace derived based on the Willis model for 002+x. The defect structure of p^o^ phase is similar to that of u0 but tile defect 2+x' structures of u308 phase are complicated due to the existence of many higber-order phase transitions. The change of defect structure of these oxides against oxygen partial pressure are shown schemat ically. The thermodynamic data such as the partial molar enthalpy and entropy and the heat capacity ate important to characterize the defect structure» The high temperature heat capacities of UO* doped with Gd or La show pronounced increases at high temperatures, of -which onset temperature decreases as the dopant content increases. The increase of heat capacity is interpreted to be due to the formation of defects. The heat capacity measurements on U40g and u3°ft elucidate the presence of the phase transition. The mechanism of these phase transition are discussed. 174 STUDY OF THE URANIUM-TRANSITION HCTAL-OXTCEN TERNARY SYSTBfi 4-28 Shinsuke YAMANAKA and Masanobu MIYAKE Department of Nuclear Engineering, Faculty of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565, Japan Compatibility of transition metal with nuclear fuel is a essential problem to develop nuclear materials and to improve the performance of nuclear fuel. In a light Hater reactor, high temperature reaction between Zr and 00, fuel is important to know the integrity of cladding under severe core damage conditions. In a fast breeder reactor, one of the major approaches to reduce the corrosion of stainless steel cladding caused by fission products is to introduce oxygen buffer or getter materials such as Ti, Hb and Cr into fuel pin, and chemical interaction of these metals with fuel is of great importance for their practical application to fuel pins. For an understanding on the reaction between transition metal and fuel, it is required to know phase relationships in these systems. Thermodynamic properties and phase diagrams are well known for uraidum-oxygen, metal-oxygen and uranium-metal binary systems. However, only limited information is available for oraniumr-metal-oxygen ternary systems relevant to the compatibility problems. In the present study, the pahse equilibria in the (Г-К-0 ternary systems Materials used in the present study were U0t, pure Ti, Zr, Hb and Cr metals, and their oxides. Powders of these materials were well ground and then mixed in the desired compositions. The pellets of mixture powder were heated at a temperature of lOOOt « * vacuum of 10" * Pa. After heating, the pellets were rapidly cooled to room temperature, and phases in the reaction products were identified by a computer controlled X-ray diftactometer. Lattice parameters of the reaction products were evaluated from reflections according to Cohen's method. After reaction of pure metals of Ti and Zr with 00* at 1000*C, a-U and uranium intemetallic compounds were formed in the reaction products. These results reveals that BO, is not compatible with pure Ti or Zr at lOODTj- Hexagonal solid solution of Ti-0 and Zr-0 with higher oxygen contents can equilibrate with VOt. Ho ternary oxide was detected in the reaction products of U0,/Ti oxides and 00,/Zr oxide mixture pellets. Reaction of pure Mb with 00, did not result in formation of uranium metal or intermetelic compound. Change in lattice parameter of DO, and Nb due to heating at lOWC indicated that UOj was slightly reduced by Mb and oxygen dissolved into the hb lattice. A ternary oxide of UNb,07 was Stable at 1000*C. From the results of U0*/Cr and U0,/Cr(03 reaction, both Cr and Cr,03 were found to be compatible With 00, at 1000Г- On the basis of the results obtained by the X-ray diffraetin analysis, tentative isothermal sections at tOOOV were proposed for D-Ti-O, И-Zr-O, U-Nb-0 and U-Cr-0 ternary systems, as shown in Figs. (a)-(d). In the isothermal sections of U-Ti-0 (Fig. 1 (a)) end U-Zr-0 (Fig. (b)) ternay systems, characteristic triangles of 00, + Dec <7 ,£) solid solution + hep a solid solution exist. Formation of {j ,0) solid solution phase can take place due to reduction of U0a with pure Ti or pure Zr. As can be seen in Fig. (c), solid 175 solution of Nb-0 nay equilibrate with DO, at 1000*C- The ternary oxide of UNt.O, appears in the O-Nb-0 ternary system. Stoichiometric UOt seems to be in equilibria with Cr and Cr,0, at 1000Г (Fig. (d>). The isothermal sections of uraniun-netal-oiygen ternary systems at WWC were calculated using excess free energy of nixing for each solid solution, which ms derived from exoerinental phase diagram of each binary system. la Fig. (e>, the calculated isothermal section of U-Zr-0 ternary systen is shown as a typical exanple. The calculated isothermal section is reasonably consistent with the experimental one indicated in Fig. (b>. The present calculation»! nethod yield a better understanding of high temperature equilibria in the uranium-metal-oxygen ternary systems. Fig. Isothermal sections of uraniua-netal-oxygen ternary systens at 1000*C. (a) U-Ti-O, (b) U-Zr-Q, (c) U-Hb-O, 176 OXIDATION STATES OF U AND Mo IN E7-MO-0 TERNARY OXIDES BY MEANS OF MAGNETIC SUSCEPTIBILITY, XPS AND ESR. C.MIYAKE and M.MATSUMURA Department of Nuclear Engineering, Osaka University/ Suita, Osaka-565/ Japan Molybdenum in fission products is well known as an Insoluble precipitate, however/ more than half of molybdenum exists in the form of nixed oxides with uranium etc.. The u-Mo-0 ternary oxide is one of the most important oxides containing uranium and oxygen. Mo0 In the present report, U2 8' UM0O5 and UMo20B were prepared together with имо7о22 and UMo1g032 and the mutual dependence of oxidation states of uranium and molybdenum in these ternary oxides was studied by magnetic susceptibility, XPS and ESR measurements. The preparation of the former three was performed as followlngs. U0,+ Mo03 US&1S 5Jlh£j >UMoOs -* "* 02 flowing ° РС PHOQ6 + U02 <70° 121u.)*\WC 46Ът„)у „ Mo0 sealed into quartz tube uo2+ иоо3 U03+ 2Mo03 &£SL^ liJUEj > UMo20B . sealed into quartz tube The remains two were prepared by heating the vacuum sealed mixture of starting materials, such as U02, Mo02, and Mo03, with a given mole ratio. The products obtained were identified by X- ray diffraction patterns as reported previously. Figure 1 shows the magnetic susceptibility-temperature curves for u2MoOg, UrtoOs and UMo2Og. A maximum over a temperature range of 40-50 К appears in all of curves. There are several possibilities of paramagnetic ions, such as и4*, U5+, Mo4+ and Mo5+/ In these mixed oxides from their chemical formulae. In spite of this fact, the effective numbers of Bohr magneton per each molecule obtained from the higher temperature region than the temperature of maximum susceptibilities are small compared with those of supposed paramagnetic ions, suggesting that antiferromagnetie interaction acts a part between unpaired electrons of these paramagnetic ions. xps(X-ray photoelectron spectroscopy)' spectra of Mo3dg/2 and Mo3d3y2 for these oxides are indicated in fig.2. The spectrum of U2MoOg is sharp like that of H0O3. For UMo05 the spectrum shifts to a low binding energy side, showing a decrease in the oxidation number. The peak of spectrum for UMo2Og is split into two peaks, one of which accords with the peak of the binding energy of Ho6+ and the ither can be attributed to No5*, in spite of л а equivalent lattice site for both molybdenum ions in the crystal. for The spectra of U4f7/2 and 04£5^2 these oxides don't show distinctly the difference of the oxidation states. Only a line- width for UMo208 is broad as being compared with those of others. 12.3ак.1б07 177 Concerning crystal structures of these oxides, -0-0-0- chain susceptibility and XFS and the crystal structures, the oxidat states of uranium and molybdenum in these oxideв are assigned shown in table. . For UMc>20g the oxidation states of 0 and No not definite at present. Oxidation states of и and Mo in U-Mo-0 ternary oxides UMoOg OMoOs U2MoOg 6 5 5 0 6 5 6 XPS МоЗЙ Mo3d3/2 Л, 5/2 UM0O5 So- 35 ко H5 »b 2Й ' 35 g§ тичкгопп (к) Binding Energy (eVI Flg.1. The dependence of magnetic Fig.2. XPS spectra of Mo3d3/2 susceptibility on temperature and Mo3dsyj 178 SOME COMPOUNDS OP PENTA- HEKAVALEN5? ACTI1J1DES WITH ANIONS OP Г"7~*—I X04 ПРЕ, WHERE X = S, Or, Se, Ко, W I " 1 A.H.Fedoseev, N.A.Budantseva, A.B.Yusov, R.N.Krot. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR Various crystallohydrates of simple Np(V) sulphate and eelenate with the composition (TCp02)2y02.nH20 (where y* S, Se; n- 0; 2j 4*5) have been synthe sized and all the eelenate erystallohydrates are iBostructural towards cor responding Np{V) sulphate. Two dibydrates with different structure have been obtained. One of them has been obtained by thermal destruction of the higher hydrates; another one- by heating of the solution Np(V) in 0.1*1.0 H of sul- huric acid in a seeled ampule at t» 18G+240QC. The structure of hydrate of Np(V) sulphatei obtained by hydrothermal synthesis hae been determined by X- ray structural method and It has been determined that its crystalline latti ce has a polymer structure and interaction: "cation-cation" plays a conside rable role in its formation. Double sulphates of penta valent neptunium and americium with the composi tion CsAm02S04.nH20; Ca-MpOgCSO.jg.aHgO, Co NpO_(SO.)2.3H20 and Co(RH3>6(H80-)Hp0s aqueous solutionfl end forms chromate with composition (Np02)2Cr04*nH-0. Molybdate end tungstate compounds Np(V) and Am(v) with the composition (Wp02)2S04.nH20, where n» 1.5*8, (NpOa>2204, where %m Mo, W, end also (Ш4)_ Np02iio4014, (HH4>3Am02 Ho4014 and KjNpOgJfc»4 014 have been obtained. Hydroxide Am(V) reacts with MoO, in aqueous solution at heating upto 100°C with the formation of the compound, which structure differs from (NpO„)oZQ4«nH^O. A new hydrate of uranyl molibdate with a composition U02MoO4»2.75H20 has been syntheeieed* from the luminescence spectrum and makes possible to assume that there are three ions of uranyl which are nonequvalsnt crystallo- + 2+ graphically. The behaviour of the ions NpOg , PuO| and AmOa in the sys tem An02 - MoO^-HgO where An«Np, Pu and Am differs considerably from the behaviour of uranyl. In the temperature range 180~25Q°C the most stable compounds are the compounds AnOgMooO™.3H~0 in case Np and Pu the analogue compound of Am has been obtained at temperature not higher than 100°C, as at higher temperature Am(VI) Is unstable. Among the products of reactions it Is possible to identify for a case Np and Pu four crystallobyOrates of neptunyl and plutonyl molibdatee whioh have different structure, one of which is ieostruotural with UOgMoO^ 2*75HgO. In севе of a system NpOj.HgO-WO.-HgO the behaviour of Up does not differ from the behaviour of uranyl the only oryatalliae product of the reaction la NpOgWgOyOKgO, leostructural towards the ваше compounds of uranyl. We have made attempts to obtain some neptunyl analogues of the compounds UO-XO., crystalline lattice of which, aa it ia known, is built with the par ticipation of the Interaction! cation-cation. It baa been determined that thermal dehydration of known NpOgyO..2.5HjO and Np0gCr0..2Ha0, which ia iso- atruetural to a known uranyl compound, proceeds parallelly with the reduc tion of Np(VI) up to pentavalent state at temperature 1б0-20О°С. tbe analyaia of IR-spectra of the obtained compounds allows to assume that, like in ваяв of uranyl, at participation of interaction cation-cation in the formation of orystallins lattioe the vibration bands of n"pOg+ are shifted considerably to a low frequency region. Thus, syetjmatlc investigation of chemistry of coordination oompounds of "yl- ions" of actlnidea has given an opportunity to Identify considerable differences in their behaviour and to assume this difference due to the decrease of interaction "cation-cation" in a row U-jts. 180 экю OF алшпдта Ада ИЙБСПЧТКГКМ OF ТЕГИамаиш UEANH, TRICAKBONATE IN THE PRESENCE OF EREft EEI F.M. Aimed, A.A. Mohamed, S. Shibani and A.V. Ananyev Radiochemical Department Tajura Nuclear Research Center Tripoli Libya Aiming at determining optiiMn conditions for precipitation of tetra- amoniun uranyl tricarbonate we lave carried out the study of effect of ancniun carbonate and amonia concentration on solubility of this confound. It was proved that increasing in concentrations of (NHJCO, and NH, in the solution causes monotonous decreasing of (NH4).U02(CO.)3 solubility down to 20 mg/1 for uraniun at [ (NH4)2(X>3 ] > 1 mole/1 and [Ш3] > 2 mole/1. It was determined that presence of ШЕА in the solution does not affect solubility of the compound up to the concentration of 0.2 mole/1. It mates possible using the process of (NH.)4U02(CO,), precipitation in the presence of ИМИ for the needs of obtaining pure preparations of uranium. A study was undertaken in purificatim of uranium in the course of preci pitation of tetraamoniuH uranyl tricarbonate in the presence of ШЛА aimed at eliminating of a ranter of metal admixture impurities. It was shown, for example, that purification factor of uraniun for iron consisted 1.7.10', for lead > 3.1.101, for REE ~ 10s which is enough for the needs of producing uranium meeting the requirements of nuclear purity. Effect of temperature on kinetics of precipitation and dimentions of emerging crystals was also studied. Possibilities for utilizing this precipitation process of (NH4)4O02(OO3)3 in the presence of EM» for final purification of uranium ore concentrate (the yellow cake) are being considered. t8< SYNTHESIS METHODS AHD PHYSIOO-OHIMICAL PROPERTIES OP 4-32 URANIUM FLUOROPHOSPHATKS V.G.Fetrov, V.P.Seleznev, S.V.Pozdnyakov. Hendeleyev Chemioo- Technological Institute, Moscow» USSR yiuorophosphates are the least studied uranium compounds. One can name on ly the paper /i/ from the literature sources, Fluorophoflphates can be divided into three groups: hexafluoropjwsphates, difluorophogphates« monofluorophos- phates. These compounds are the derivatives of the corresponding fluorophoe- phoric acids. Uranvl with hexafluorophogphate-ion compounds. When HPF, reacting with uranylfluoride in hydrogen fluoride acid the oompounds of uranyl with hexa- fluorophosphate-lon are formed. The composition of coinpounde depends on the T n HP concentration of J02Fa * (40$). The general formula of jompounds is: Нв/ио2(РР6)Ъ Pe(H20)d/, b+c+d • 6, b+c-a+Z. It is established that the ma ximum ratio of P/U in these compounds is near to 6, that corresponds to the compound H./U02(PPg)g/ or U0a(pi?g)„MHTF,, The compounds are unstable under usual conditions. The oompounds of these substances with dlmethylformamide (raiFAl are synthesized: Н^ио^дф^ЭШРА, U0a(PP6)2-4I»A and kallum salt of these complex acids-Kg/UOa(?Fg)P-(H2o)2/. IR spectra and x-raymetric data of such compounds are obtained. A more detailed description of these com pounds is given in the paper /2/. Hexafluorophosphate*ion with IP* compounds under the same conditions are not obtained* Uranium difluorophoaphateg. Several methods of obtaining uranium dlfluoro- phosphatea are worked out. Some reactions can be given as an example: 4U0j + 1OHP(l)+2KI5-»-UO2CPO2P2)a+3UO2P8+1OH0l t, (1) 2UOaP2.2H20+2P015+2HP(l}-^U02(POaP2)2+UOaPa+IOHCl f , (2) 2uo4»3H2o+8HP(i)+4Poi5-^auo2(po2P2;2+aoHCit +oat, (3) 2UO2+2P0Pj -^U02(P02Pa)2+U02Pa, (41 U03-HaO+2POP3 —U02(P02F2>a*2KP, (5> I6UP4'0.5H2O+4PCI5+4EP(I! -~o(POaP2)4+i5UP4+aoHci1, (6) 16UP4- 2.5H2O+2OP015+4OHP(l! — 5U(PO2F2)4+11UP4+1O0HCl t. (7) IR spectra of uranium dlffluorophoaphatee and X-raymetrlc data of the com pound UOg^POgFO» are obtained. When studying thermic behaviour of uranium dlfluorophoephates by derlvatographio method, it is established that the following reactions la the Interval from 15O-500°c in the argon atmosphere go: U02(POaP2)2 J^~ UO?P03F+POP3 < , (8) 1/2 O.P02F2)4 JL 1/2 U(P0jF)a+POP3 t , (9) In the system UOgCPOgPj)g-UO-F, the formation of the compound,which has the formula UOgtPOjFj'P is established. It la also established that decompo sition of UOgCPOgFg)? begins above 130°C The decomposition reaction can be presented in the following way. 2UOa(P02P2)P JEi. TOgPOjP + UO^ + POFjl . (10) 182 Uranium monofluorophoaphatea. Uraniumraonofluorophoephatee ca n Ъе obtained from the corresponding difluorophosphates Ъу heating. IR spectra of uranium monofluorophoaphateB- and X-raymetric data of the compound U02PO,F ar« obtained. When uranium compounds reacting with monofluorophosphoric acid, when the lat ter la taken in plenty, the complexes have the composition UOjPOJF»ZHgPO.P, u4P0,F)2*2H2P0,F. IR speotra and X-raymetrlc data of these compounds are ob tained. It is sr im that the decomposition of monofluorophosnbatea goes in the following reaotionei 3U02P03? -£- (402)j(K>4)24-POPjt , (11) 3/2 U(PO3P)2 -£*• i/a U3(PO4)4+POP3/ . (12) :he temperature interval of the decomposition reaction of uranyl monofluo- rc Losphate is 68O-720°C, uranium monofluoropho&phate (IV) - 65O-7O0eC. On the basis of teneimetric investigation results of uranium fluorophoa- phates dlcompoBition reactions the thermal effeots of these reactions are defined: Reaction 8: AHa, 298 • 89.6+1.2 kJ/reaction. Reaction 9: 298 • 109.4+5.0 kJ/reactlon. лва. Reaction 10: AHd. 298 - 78.2+1.9 kJ/reactlon. Reaction 11: AH!. 298 • 193-8+3.0 kJ/reaotlon. With the help of theae data the evaluation of formation enthalpies - AHj, 298 of compounds: tK>2(P02F2)2, HOjdVjPj)?, UOgPOjP. References 1. Vast P., Semmoud A. // J. Fluor. Chen* 198$. Vol, 27. F. 47-52. 2, Petrov V.G., Selezsev V.?. et al. // Chemistry and technology of rare and diffused elements. L.t LTI Fuel., 1989. P. 129-143. 183 ;,-V_ STRUCTURAL AMD CHEMICAL ASPECTS IN MIXED LIGAND URANYL 4-33 COMPLEXES AND RELATED COMPOUNDS R.N.Schelokov, Vu.N.Mikhailov. A.V.Sergeev. V.E.Mistrjukov, A.G.Beyrakhov Institute of General and Inorganic Chemistry of the Academy of Sciences of the USSR, Moscow, USSR Behaviour of traditional ligands in a substitution reactions in uranyl coordination compounds is desoribed by a rule, previously determined by I.I.Cherniaev and R.N.Shelokov. Prediction abilities of this rule is proved on a wide experimental matherial.For example, synthesis of binuclear peroxo-oxalate3 L,ZQ4^; UO -02-U0^ ZZQ* \° , F- ^F ]•<- oxalato-fluorides X—UO,-(CO )-UO„—X and oomplexono-fJuorides £,;UOz-(edta)-UO^p\*~ show not only reaction route, but. also final complex structure. That structure is also proved by single crystal X-ray diffraction analysis. Mixed ligand uranyl complexes also show great variety of car- boxylic groups structural functions. Untraditional ligand behaviour in actinide complexes can be predicted for uranyl complexes with hydroxylamine and a-dioximes, but final complexes structures are unexpected, so they can be determined only by X-ray analysis. All mentioned structural and chemical aspects are illustrated on-reaotions and molecular structures of mixed ligand complexes of uranyl, uranium(iy), thorium(IV), neptunium (TV), r,iroonium(IV), hafnium(IV) and rare earth elements. 184 'J-JJIb'CSmQN AMU STRUCTURE OP FLUORO-COMPLEXONE COMPOUNDS" 4_34 OF SOME f-ELEMENTS LZ— A.V.Sergeev, V.E.MistrJukov, M.G.Juravlev.Yu.N.Mikhailov, R.N.Schelokov Institute of Uenei-al and Inorganic Chemistry оГ the Academy of Sciences of the USSR, Moscow, USSR Systematic study of uranyl comlexes with different attacking arcidio ligands made establishment of their possible main rules formation. Рог mixed ]i£.ind peroicido, '-.«rboxylate, ami.nopolycarbo*ylat* urany]. complexes found .Caetores, defcerming their chemical proper ties and structure. It is nhnwri. that, in complexes o.f 'J(LV) and related ions, such as Th(tV), Np(IV) edta anion is bexadentate and has twist conformation. Detailed otudy of mixed ligand edta and fluorine i:r carbonate oomlexes is reported. Synthesis and X-ray structure analysis for- fluoroetliylen- diaminetetraacctic coplexes of rare earth elements, ZruV) , Hf(IV). Sb(III). Bi(III), V(III) etc. is discussed. Mutual influence of fluorine, carbonate and edta*"-ligand is examined. Main rules of formation and geometric characteristics of isolated compounds are reported. 185 STRUCTURE CHANGE OP URANIUM!IV) TETRAHALIDES ADDITION COMPLEXES WITH UREA BETWEEN SOLID STATE AND SOLUTION DETECTED BY MAGNETIC SUSCEPTIBILITY I , ,- 4-35 Chie MIYAKE, Nobuyasu ICHINOSE and Vukio HINATSU Department of Nuclear Engineering, Osaka University Suita, Osaka-565, Japan Pour samples, UC14- 2tetramethylurea(TMU), UCl4»2tetra- ethylurea(TEU), UCl4* 2dimethylethyleneurea{DMEU) and UBr4 • 2DHEU were prepared according to the literatures [1][2]. Structure configuration of these complexes was investigated by magnetic susceptibility measurement. In a solid state and a solution state, magnetic susceptibility was measured by a Faraday type magnetic balance and a high-resolution proton magnetic resonance method [3], respectively. All of these complexes in the solid stat^ exhibit temperature independent paramagnetism characteristic of U(IV) in the crystal field with an octahedral symmetry (Fig. 1). In the solution state, the magnetic susceptibility of these complexes depends on a coordination ability of the solvent molecule. In dichloromethane, these complexes have temperature independent paramagnetic susceptibility (Fig. 2). However, these in methanol which is coordinative solvent have temperature dependent paramagnetic susceptibility as shown in Fig. 3. The change of magnetic behavior in methanol can be attributed to lowering symmetry from the octahedral caused by the coordination of the solvent molecule. This fact of the coordination by the solvent molecule can be proved, for example, from the change of IR spectra of DHEU indicated in Table* The ligated molecules of DMEU become free because of a substitution by the solvent molecules in methanol, while they remain bound to U(IV) in chloroform. Moreover, the suspension of U(IV)-alcoholate was at last observed at the bottom of the container. Infrared Spectral Data of Complexes Complex (/(CO) (cm"1) (MN-C-H) (cm"1! in CH3OH in CHC13 in СЯ3ОН in CBCI3 OHEU II I 1689 1519 1509 UC14-2DMEU 1616 1562 UBr4 - 2DMEU 1613 1572 186 - •••ggs. О : UBr4<2DHEU • : UC14-2TEU Д : UC14-2THQ Л : UCI4-2DMED 10О 200 Temperature С К) Fig. 1. Magnetic susceptibility in solid state UC(4-2Teil ' uat-2iMU 200 250 MO т«лрсга1иге<К) Temperature(K) Fig. 2. Magnetic susceptibility Fig. 3. Magnetic susceptibility in dichloromethane in methanol References 1. K.W.Bagnall, J.G.H.du Ргеег and M.L.Gibson// J.Chem.Soc. A, 2124(1971) 2. J.G.H.du Preez, B.zeelie, U.Casellato and S.Graziani/i Inorg.Chim.Acta, 129, 28*11987) 3. D.F.Evans//J.Chera.Soc, 2003(1959) ss THB SPECTRA AND STRUCTURB OP URAHYLOXALATB COMPLEXES I ' | WITH NEUTRAL LISAHDS I I I K.A.ChumfleYBkil, O.U.Snaropov, N.A.Minaeva, H.T.Toanev. Institute of General and Inorganic Chemistry of the Academy of Solencec of the USSR, Moscow, USSR In thie paper are presented the results of Investigation of the vinratlo- nal and luminescence spectra of uraoyloxalate conpleies with neutral Uganda of tne type (U02)2C204I2-L4, «here neutral Uganda L -• diasthylurea - ICaoi- doligand I-SCS), - II(I-CL), - III(X-Br)t totramothylurea - IV| dimotbylsulf- oxlde - Vi dimethylformamide - Tit diethylforaamlde - Till dlnethylaoetanlde- VIHCI-Cb). With the various possibilities of oxalatogroup ooordlnation at uranyl com plexes (without X-ray data), it «as interesting to investigate Ш, Вешан and luminescence spectra of these complexes and to conelusa about their structure. The vibrational frequencies of oxalatogroup, uranyl ion and neutral Uganda at tne compounds I-VIII with vibrational frequencies of the simple oxalates, D02C2(V 'H2°ao d pure oeutrel lleanaa were the ease for that information. We Bade the interpretation of spectra by fragaental vibrational analysis of ura- nyl compounds, The first conclusion is,- compounds I-VIII have uranyl group with penta- coordination. The second conclusion Is,- oxalatogroups at compounds I-VIII are planar with (bis)bidentate coordination. These conclusions are results the vibrational analysis of the simple oxa lates, UOJCJO^HJO (this compound have planar oxalatogroup [1] ) and compo unds I-VIII. Thus, the compounds I-VIII have the, following structure: e - 0 ®-«r О -о ® - acldoligand. The complexes (UOjJgCgO^Xg-L^ constructed by syametrio type with tetraden- tato oxalatosroup, bonding two pestagonal-bipyramldal polyhedra of the uranyl ions, Uganda L are conjugated with Uo|+ by C-0 CS-0) bonds. At last, interpretation of the vibrational frequencies for oxalatogroups with (bis)bidentate coordination at compounds I-VIII is interpretation for "free" planar oxalate ion [2,3]' • This interpretation made by analogy with model of oxalatogroup D2b symmetry, where C-0 bonds are equivalent. References 1 Jayadevan B.C., Chaokraburty D,H.//Asta Cryst. 1972. Vol. B2B, H11. P.J178. 2, Chumaevskii N.A,, Sharopov 0,0,, Klnaeva N.A.//J,Inorg.0hem.(05SR). 1988. Vol, }3, И6. Р.1390. 3. Chumaevskii ff.A., Snaropov 0.tr.//J.Inorg.Chem.(USSR).1988. V->1.33,B8. Р.1914. IHOXOUUANIUM(VI) COMPLEXES KITH CARBONYL DONORS Г~4-37~ S.Sitrnn, li.Fregona, P.Guerriero, Istituto di Chiraica о Tecnolo£i.-i dei Radioclemcnti, C.N.R., cdrso Stati Uniti, 35020 Padova, Italy G.Faraglia, Dipartimento di Chimica Inorganics, Metallorganicn ed Annliticn doll'UniversitU, via Loredan 4, 35100 Padova, Italy Recently we reported a study on the behaviour of uranyl complexes with difonnylphcnols in alcoholic media |_l-3j. The ligands Z,6-di_ Гогшу!-("Chlorophonol, ll(l)IAL), and 2,6-di£orroyl-<*-methylplicnol, ll(MUA), undergo in refluxing methanol acetalation of one of the aldchydic groups to give the corresponding 2-dimethylacetnl-6-formyl_ phenols. In the opportune conditions the reaction of uranyl salts and diformylphenols yields either the complexes [UO^LKtL1)] (I, » DIAL or МПЛ; L* = 1IZ0, MeOll or EtOIl) or the corresponding ncotalnted species IIw ciyslal «tiuctuic of whicli have been isolated and t haracteriied by infrared and NMR (lll and I*) spectroscopy and thermogravimetric measurements. The fo£ mat ion of acctal groups is of importance when template syntheses of urnnyl Schiff base complexes are performed in alcohols. Parti.il or total acctatation of formyl groups prevents condensntion leading to mixtures of reaction products. When the complex of F£g,l is геле Х ted with diamines П^ЩСН,) 2^2 (X - Nil or S) the corresponding acetalated Schiff base complexes are obtained. As a general trend, acetalated moieties arc easily formed in methanol whereas ligands and complexes containing diethylacetal groups are less stable. 5ear_ cc evidence of acetalntion is observed when complexation occurs in isopropylic alcohol. With the aim to prepare uranyl Schiff base complexes containing free sites to insert other metal ions, we extend the study to 2,4,6- •heptanetrione derivatives. The reaction of various uranyl salts with this ligand yielded generally complex mixtures, whose infrared or NMR spectra suggested the presence of either heptanetrione or 2,6-dimethyl-4H-pyran--l-one (DMP) complexes. Dimethylpyrone has been found to form when heptanetrione is left on standing for a long time or is heated for several hours. 189 о In this line we examined the uranyl nitrate-DMP and uranyi-aceta_ te-DMP systems in benzene and in methanol, in the first solvent the adducts [U02(WP)2(M03)2] and [U02(DMP) [0^0») J have been obtained, whose infrared and NMR spectra are in accordance with ligand coord£ nation through the carbonyl oxygen aton. ft»-7J. *n fact the v(C=0) absorption, at 1611 cm in free DMP, undergoes a low energy shift of order of 70 era" in the adducts. The proton NMR spectrum of DMP in deuterated chloroform shows the CHj and CH proton signals at 2.21 ppm and 6.01 ppm respectively, which are shifted downfield on coord± nation. The effect is larger for the CH singlet, which is observed in the complexes at ca. 6.8 ppm. Moreover the C=0 carbon resonance is in the complexes ca. 15 pr-m downfield with respect to the corres ponding* resonance for DMP (170 ppm) . When the uranyLsalt-DMP reaction is carried out in methanol, the product nature depends on the salt anion. Whereas uranyl nitrate forms the 1:2 adduct in a nearly quantitative amount, uranyl acetate yields a solid which does not contain acetato groups and whose anaU tical and thennogravimetric data support the formulation iX^tOH^.DMP.ZH^O. Conversely infrared absorptions and proton NMR sig nals could indicate partial transformation of DMP into heptanetrione with consequent formation of either DMP adduct or heptanetrionato complex. REFERENCES 1. S.Sitran, D.Fregona, G.Faraglia et al./ Inorg.Chim-Acta, 121, 103 (1986). 2. S.Sitran, D.Fregona, G.Faraglia et al./f Inorg.Chim.Acta, ^32_, 279 (1987). 5. S.Sitran, D.Fregona and G.Faraglia/M.Coord.Chem., 16,' 395 (1988). 4. E.M.Briggs and Л.E.Hill, J.Chem.Soc.//200S (1970). 5. F.Kutek and B.DuseM-Russ.J.Inorg.Chem. (Engl.Trans!.). i£, 12S9 (1974;. 6. A.De Jager, J.J.De Vrieze and J~.Reedijk//Inorg.Chim.Acta, 20, 59 (1976). 7- [.Wharf, T.Gramstad et il.ff Can.J.Chera. 54, 3430 (1976). 190 SYNTHESIS AND PROPERTIES OF URANYMVI) COMPLEXES WITH A NEW COHPARTHENTAL SCWFF BASE 4-33 U. Casellato, p. Guerr'ero and Р.Л. vigato tetltuto dl Chimlca e Tecnologia del Radloele c. so Stat» Unit!. 4 - 38080 Padova - ita* Uranyl complexes with simple di-, ter-, tatra- and penta- dentate selwff bases have been ayntheaiaed and characterized by x-ray effraction. Ноге recently dmucleatmfl and/or compartmental ligande have been prerared and their interaction with f-ions studied. With these Uganda It is possible to study the mutual interaction between the metal centres, held together In close proximity by the nature and the shape of the coordinating ligand. Magnetic exchange interactions, energy transfer processes together with multielectron redox reactions» activation of small molecules, etc. have been extensively studied. AS an extension of the dinucleating systems already Investigated, we have preparer the uranyl(Vl) complex with the ligand and the v3 o-u-o at вез cm V Red brown crystals of U02(H2L) dhuethylforma- mide, suitable for a x-ray investigation, have been obtained by dissolving the crude product in the •rintaum amount of dimethylformamide contai ning some drops of methanol H4L and allowing the solution to stand overnight on an atmosphere saturated by diethytether. The crystals are monoollnic, space group P2f/n with e=21.165(6), bsll.B33(4), C:9.«T9(4) А: В =102.34(3) ; Dc =t.9l g. cm-3 for Z=4. The structure was refined to the conventional R of 4.6/.. г+ The pentadentate dianionic ligand binds equatorlaily to иог leading to a seven coordinated uranium In a distorted bipyramidai coordination geometry. A molecule of dimethylformamide la hydrogen bonded between the two free ОЗ and OS phenolyc oxygens of the ligand. selected bond distances are: U-0(uranyl)ci,T9 A (mean); u-0(ligend)=2.2S5 А; и-н=г.61(1) A. All these distances compare well with corresponding values in similar compounds. — The uranyl complex UOg(H2L) has teen used for the preparation of hetero- and homo-dinuclear complexes. In particular the Interaction of this complex with lanthanide and transition metal ions has been studied together with the formation of homodinuclear uranyl complexes. 192 SPECIFIC CHJMICAL BEHAVIOUR OF (Л-БЮХШЕЗ Ш URAHYL 4-39 COMPLEXES A.O.Beyralchov, I.M.Orlova, V.E.KLstrjukov, yu.H.Mikhailov, R.N.Schelokov. Institute of General and Inorganic Chemistry of the Academy of Sciences of the USSR, Moscow, USSR Interaction of uranyl compounds with d-dioximes leads td formation of stable complexes of different types. Structure of isolated compounds proved by single crystal X-ray difraction studies of 5 typioal complexes. Main coordination abilities of o(-dlcximes and conditions of their realisation are determined. Correlation between the type of final complex or llgand geometry and the way of ot-dloxim bonding to uranyl Ion is discussed. For example, symmetric sub stituted oV-dioxlmes (such as glyoxiK, dime thy lglyoxim) may be bonded to uranyl ion in 3 different ways, shown in Fig. (1,2,3). Asymmetric substituted 0(-dloximes (methylglyoxim) may be coordi nated only in a ways, shown in Pig. (7, 2). 1,2-Cyclohexanedlondioxim besides 1 and 2 ways may be bonded to uranyl ion as shown in Fig. (4, 5). R 4 0-0" R И 0 q—p« •4 "£ Ч (i) (2) •КО—и ^с—с^ Я" ,И 05) во. ;.С С: .о~"5Г.. ..?•-«» "О, щ~ '"К (3) (4) 13.3ак.1607 193 AMIDE AND PYRAZOLIDE DERIVATIVES OF.UCU[HBpz3]g 4-40 I Isabel Santoa and A. Pi res de Matos Departamento da Ouimica, ICEN , LNETI P - 2686 Sacavem Codex Portugal Complexes of the type UC1(NR2)(HBpz3)2 (R=CH3. CZHS, CeHs> and UCl2-»(C3H3Nz)»(HBpz3)z [1] I. Santos, J. Harcalo, N. Marques and A. Pi res do Matos, Inorg. Chim. Acta, 134. (1987) 315 VAPORIZATION ADD THERMOLYSIS OP UftlBYL ji-DIKEIOIMXBS I—— 1 E. If. Rubtaov, Khlopln Radium Institute, Leningrad, USSR Ability for reversible vaporization of some aetinide complexes with 0-dxketonea makes them potentially suitable for use In processes of separation and purification of metals, deposition of metal-containing films /1*37* Recent publications deal with investigations of vapor pressure dependence on temperature for some uranyl ;-diketonates Д-107- It is necessary to note, that quantitative characteristics of vapori sation are scanty for prediction of suoh an essential parameter ав mass- transport completeness, because the possibility of simultaneous thermal decomposition is not taken into account. The main part of Information on U02(dik)g vapor pressure /5-S7 «as obtained by flow method that is Insensitive to decomposition pattern is the process of the experiment. Ihe data on UO„(clik), thermostability are not numerous and unsystematic. The object of present investigation was to determine the thermosta bility temperatures and quantitative characteristics of masa-traseport process for aoetylacetonate (ro,(acac)2 (*Ц • Hg " aate U02(pvac>2 (R1 - BWU^y R2 • OHj), iaobutyrylaoetonate 00g(ibac)2 (R1 - CH(CH,)2, й2 > OH,), dipivaloylmsthanate UOgCdpvnOg (R1 - «2 - C(CHj)3), benzoylacetonate UOg(bzac)2 (В, - OgHj, Kg - OHj) and benzoyltrifluoroacetonate U02(oztfac)2 (R1 = OgH-, Eg » CP,). Temperances of the beginning of vaporization (Т*) and mass-transport completeness near these temperatures were determined under external pressure 0.3 Fa. Helting temperatures and thermal effects responsible for the decomposition to black carbon-like substance (x_) were marked out on the differential thermal analysis curves recorded under argon. Гае following sequence of the beginning of vaporization temperatures has been worked out on the basis of the information obtained U02(dpvm)2-sUOg(acao)2 proved to be wrong. For example, in the cases of 0"02(ibac)2 and UO.Cpvac), vaporization begins considerably below melting temperatures (133-155°C, 120-HO°C), in the oases of Ш>г(асас>2 and UOgCdpvm), this process starts far below melting points <200-222°C, 200-210°C). The sequence of the beginning of decomposition temperatures (Тг) has been worked out OOa(acac)2 Decomposition of U02(b2ae)g and U02(bztfao)2 runs sxothermally in argon atmosphere, the change of pyrolyele mechanism with aromatic radicals introduction being supposed. 195 T It is evedent that difference AT » I2" 1 is onaraoterietio of thermal stability of the coaplexeaee, the sequences of AT and шавв- traneport eoapleteneaa coincide full; O0a(b!!ae)2 References 1. Trerolkov S. 3. et al.//Teoreticaoekaya i prikladnaya Ichimiya JS-ddketonatov metellov. H.i Bauka, 1985. S. 220-223. 2. Travnikov 3. S. et al.//Ibiden. S. 224-228. 3. Danllin L. D. et al.//Radiokhiaiya. 1987. I. 29, Ж 6. S. 700-703. 4. Bketrov Л, et al.//Inorg. Bud» Chen, betters. 1987. Vol. 14. H 8/9. P. 301-306. 5. Sidorenko 0. T., Suglobor D. B./ZBadiokhlmiya. 1987. T. 27, В 6. S. 718-716. 6. Sidorenko 0. T. et al.//Radlokhimiya. 1983. T. 25, В 4. 8. 476-482. 7. Sidorenko a. V., Saglobov D. H.//Badiokhiniya. 1983. T. 25, H 3. S. 354-361. 8. Sidorenko G. 7, Suglobov S. H./ZBadloknimiya. 1983» I. 25, В 4. 3. 473-478, рнсвиав OP SJHTHBSIS AKD SEPARATION OP VOLATILE ACTINIDE 4-42 Ji-DZKBTOBATBS A.V.Davydov, B.V.Pedoseev, U.X.Alsenberg, S.S.Travnikov, B.P.MyaBoedov. Vexnadaky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Moscow» USSR The methods for BynthesiB of miего-amounts of volatile metal A-diketona- te complexes are discussed. The use of extraction ae well as nucleophilic exchange of ligends in the reactions of chloride hydrates or thenoyltrifluo- roacetonatea with ft-diketonee* vapours has made it possible to obtain ft-di- ketonates of actinide elements. For the first time there were synthesized mendelevium and fermium volatile hexafluoroacetylacetonate complexes. The^e was studied the thexmochromatographic behaviour of the obtained complexes in the flow of carrier gas, saturated with ligand vapours. It has Ъеев found, that the volatility of mendelevium and fermium hexafluoroacetylacetonates is close to that of analogous compounds of lanthanides (Tb, Eu) and more light actinides (Of), having +3 oxidation state. This fact has made it possible to suppose mendelevium and fermium to have the same oxidation state in these complexes. The possibility of formation of mendelevium tris-hexafluoroacetyl- acetonate with high yield (more than 80$) through interaction of hot mendele vium atoms with bexafluoroacetylacetone vapours in on-line operation has been shown and the transport of this complex in thermochromatographic column has been carried out. The separation of scandium from lanthanide and actinide elements by means of thermochromatography of -their hexafluoroacetylacetonate complexes has been achieved. The method for the separation of cyclotron ra dionuclides, worked out on the basis of the gas phase reaction between hot atoms and 6-diketone vapours, has been applied to the separation of lantha- aide and actinide radioisotopes including the element-102 .я It has been demonstrated that thermochromatographic method can be success fully employed to the separation of actinides, having different oxidation states, for instance U(VI), Pu(I7) and Am(III) as well as Th(IV) and U(VI) in the form of volatile hexafluoroacetylaoetonates, resulting from the treatment of their chloride hydrates or thenoyltrifluoroacetonates with hexafluoroace- tylacetone vapours. The adducte of californium hexafluoroacetylacetonate with tributylphospha- te, tributylphosphineoxide and dipropylsulphoxide have been synthesized. By using the flow method with programmed temperature the vapour pressure tempe rature dependence of these compounds has been measured and the thermodynamic characteristics of sublimation calculated (see the Table). Thermodynamic Character!sties of Californium Hexafluoroaoetylacetonate Adducte* Sublimation Compound (A.IO5)/! ДН, В A kJ/mole J/mole-degree Cr(HFA)?-2TBP 15.02+0.7! 6.95+0.52 153-0*6,1 308.0+15.0 cf(HPA)3-aiBPo I?.B8*p.21 6.82+0.10 130.6*1.9 285.0+4.3 Cf I An (III) AnLjj Anlj.aS; > AnL4 (to » ПВ) , An (IV) Anb4J AnJ^T.^; Anb^.S (An - Th, «, Hp, Pu, Bk ?) , An (V) AnLj/OlOg^ (An = Us n«3) An (V.1) Ап021г; AnOgLg.S; AnOjLj (An > 0, Hp, Pu) , £-Diketonatea of An (IV) form adducts only in the case of fluorinated acidoligands. On the other hand, the volatile different-ligand complexes of An (IV) have been obtained only for non-fluorinated L. While volatile uranyl Jb-diketonatee exist in three chemical forms, the correponding compounds of neptunium and plutonium (VI) are known only in the form of adducte; the attempt of their desolvatlon leads to the oxidative decomposition with partial formation of actinoid (IV) chelates. 198 fi-Diketonatea of An (III) and in (VI) tend to coordinative polymeri zation, and in this case too adduot formation car load to tho riao of volatility. The tendency for volatility growth with the decrease of the basicity of neutral Uganda has teen found, Ibe most volatile among the actinoid Э-diketonates are so far hexafluoroaoetyiacetonatea of An (IT) subliming in vacuum with noticeable rate even at room temperature. Among the t-diketonatea of in (HI) and An (71) the most volatile are, probably, the adducts of baxafluoroaoetylacetonates with ether-type Uganda. In addition to J-diketonates a few chelates of aotinoida (IV) with Uganda forming five-membered rings (e.g. hydroxamates) aa well as macrocyelic ohelatea of An (IT) and An (T) (natalooyanlnea) are known. In actinoid chemiBtry most often nitrates and earboxylates have also chelate struoture. tTrsnyl nitrate and trifluoroacetate are volatile only in the form of adducts with atrong neutral Uganda (e.g. trimethyl phosphine oxide, hexamethyl phosphorus triamide). Among non-fluorinated carboxylatea only the salts of 0 (IT), D (TI) and Th (IT) with anions of branched carboxylic acida are volatile. All these compounds are leaa volatile than p-diketonatea, but lower cost of the Uganda used may be advantageous. The principal possibility cf application of volatile actinoid chelates for the deposition of oxide eoatinga, the separation of elements and iaotopes with the use of sublimation, gas chromatography and photochemistry methods ha a been shown. 199 VAPORIZATION OP COOKDIHAMOH-SATURATED URANIUM COMPOUNDS 4-44 V.O.Sevast'yanov, N.T.Kuzneteov, S.V.Krasnodubskaya, O.V.Kurtasov, A.S.Alikhsnyan, I.Yu.Pllatov. Institute of General and Inorganic Chemistry of the Aoademy of Sciences of the USSR, Moscow, USSR experimental material on vaporisation ргосеавев of uranium compounds with a molecular structure has been analysed. le have prepared and iden tified 1-n-butylcycloctatetraene of uranium, (OgHginCCgH^O^Pq11), tetrakis (2,6-dlmeBnyl-2-methoxy-3,5-boptaneaionate) of uranium, U(C10H170,)4, tet- rekia(2,6,6-trimethyl-2-methoxy-3i5-heptenedlonate) of uranium, UXO^&JQO,^, and tris(cyolopentadianyl )-u-butoxide of uranium, (СсНе)^С0С4Нп • for the above compounds we have determined melting points and enthalpies, eva poration and sublimation enthalpies. The specifics of conversion to the gaseous phaae have been made. We beve worked, out methods for evaluating the coordination capacity of Uganda and possible numbers and types of intermolecular contacts for the oaoe of compounds with the known and "designed" (molecular mechanics) str ucture. To characterise the degree of filling of the coordination space at the central atom (OA) of the complex we calculated the function of the spe cific eurface of the ligand section by a sphere with the centre coinciding with the CI coordinates, aocording to the distance to the central atom. Cal culations were ldde by using a program compiled Is application to the pers onal computer Hewlett Paccsrd-ббВ. The key algorithm of the program involved the determination of the statistically confident array of points of the sph ere with a radius eg.ua 1 to the van-der-Wosls radius of C* (urssocens, oyelo- pentadlenyl derivatives, alkoxides, alttylamides, etc.). It is shown, for Instance, that for fi-diketonatas of uranium the determining role in the fil ling of the coordination sphere of the central atom is played by oxygen at oms of lig&ads (first coordination ap.nsre). The extant of screening by the second coordination sphere (hydrocarbon frame) is lees in all cases. To es timate the possible realization of the types end number of Intermolecular contacts in organoalemental compounds for identical molecules we have work ed out a program the algorithm of which is user; to realize arbitrary rota tions of each of the two identical molecules, whereupon the pjint of "cont act" is determined. Calculations have revealed the presence of only hydrocar bon contacts in alkylurenocens, B-diketonates of uranium (IT) and additional contacts with oxygen participation in uranium hexamethoxlde and hexaethoxida. we have elaborated the approach for a quantitative assessment Bnd forecast of volatility tried out earlier fij on uranocens. A scheme for calculating evaporation enthalpies for coordinetlon-sstuxatsd uranium compounds is propo sed. Parameters used for calculating evaporation enthalpies of organic comp ounds are shown to be suitehle for calculating evaporation enthalpies of or- ganoelemental compounds under the condition of a complete screening of the metal atom from participation In interaolecular interactions. This enables us to analyse experimental values of vaporisation parameters; to draw conclusions on the molecular structure of compounds end to carry out a purposeful synthe sis of substances wltu preset vaporization enthalpies. Reference 1. Devyatykh G.G. et al.//Abstr. Inter.Conf. of Nuclear and Radiochemietry. Lindau, 1984. P.51. 200 INDRNYL COMPOUNDS OP THORIUM AND URANIUM J.9offart, 3.Bettonville. Institute of Radioehemlstry, University of Liege, Sart Tillman, B-4O00 Liege, Belgium .The organometallic chemistry of if- and 5f elements is undergoing rapid development and a rich chemistry is being observed* Our investi gations involve indenyl and alkylsubstltuted indenyl groups as eo- ligands. A series of Uganda has been prepared from CgHg to (GH,)„GgH. In general, the replacement Table I Acidity of some indenyl ligands ^iydrooarbons pKa in DMSO C H 20.1 9 8 21 2-CH3C9B7 21.8(1) 22.5(1) Э-сн3с9н7 1,,4,7-(CH3)3C9H5 24 2,3>i.5,6,7-(0H3)6C9H2 26.5 1.2,3,4,5,6,7-(CH3)709H 27 27.4(1) Actually it is possible to prepare various indenyl compounds with different geometries from pseudo tatrahedral to pseudo octahedral pentagonal (Table II) Thorium and uranium bond disruption enthalpies have been determined for some compounds. Tb/j actual values are in large excess of values reported for id element compounds and larger than the values reported for eyelopentadienyl analogs (Table III) 201 ТаЫв II Carbon-aetal distances in indeayl compounds Compounds Hl.102(nm) W..io2(nm) IndjO 27.95 0.19 IndnBr,.THF.TPhPO 27.59 0.62 IndD3r3.2THF 27. 2S 0.70 IndOCl3.2IHF 27.ЛЭ 0.80 IndjOfBH^jj 28.88 0.77 2+ ((1п4»Вг(СНэ0Ю4)2)0 28.55 1.15 f (IndDBr2(OH3CN)4 ) 28.15 1.52 IndjUCl 27.77 1.38 IadjUBr 27.78 1.39 IndjIII 27. B2 2.02 THIjThCl 28.63 1.67 TMIjOCl 27.9* 1.05 HexMI^UCl 28.36 1.39 ML i mean distance of carbons of the C* ring(s) to metal DL : difference between metil-(STTcZ) and metal-fc.., C2, C-.) distances Table III ExperiDental Bond Energy Disruption Enthalpies (kj/mol) IndjThCH, 1-EthylindjThCHj IndjOOHj 1-EthyllndjBOHj 373.5 + 5.2 36*.8 i 5.0 351.2 i 1.6 350.1 i 3.5 Reference LBorvell F.O. and Bauseh H.J.//J. An. 0h9m. Soo. 105,6188 (1983). 202 ELECTRON EXCHANGE ACROSS BRIDGING UGANDS IN BINUCLEAR COMPLEXESOFTHEf-BLOCKMETALS I 4-46 R.K. Rosen. D.I. Berg, Ш. Boocella, R.A. Andersen, and N.M. Edelstein Chemistry Department, University of СаШотта, and Materials and Chemical Sciences Division, Lawrence Berkeley Labonttcry, Berkeley, California 94720 USA Electro exchange interactions across ligands thu bridge two metil centers are of considerable имеем in chemistry, matedal science» and physics. Exchange interactions are common in d-transioon metal chemistry in condensed ptoses and шпюкси1аг compounds though га» inthef-mmsition metals, раг^иЫушпюЬпЛагсттрошиЬ. We will present results, mainly derived ftomvariabl e tempentme (2-КЮК) imgnetic snsceptibffity studies, that show that electron exchange does not occur in molecules such as [(MesCsbYbJiTli-E] or [(МеСзВДзЦОД-В) where E is an inorganic cbalcogenide atom such as tellurium. In contrast, organic ligands that bridge the two lanmanide centers, such as bipyrimidine, provide a pathway for spin exchange interactions since the molecule shows antifeiromagnedc ampling wim an om^ing teD3perature of 12K. In addition, coupling between the two pentavalent actinfcJe centers, (МеСзОДзи, linked by the 1,4-diimidobenze!K: ligand, NCgHUN, is observed with an ordering temperature of 20K. Attempts to understand me nature of me exchange mtenciranswffl be presented. Acknowledgement. This wedt was support by me Kieciw.Oflnkx of Eivergy Research, Office of Basic Energy Sciences, СЬитсп! Sciences Division of the U.S. Department of Energy under Contect No. DE-ACO3-76SF00098. ENDOR OR AN ORMNCJETALLIC COMPOUND OF TSIVALENT URANIUM 4-47 by Edgar Soulie and Jean-Francois Le Marechal CEA CEM/5ACLAY МРСУ5СИ UBA CNRS 331 91191 Oif sur Yvette Cedex - France and Dldier Courier Ecole National* Superieure de Chinie de Peris 11, rue P. & M. Curie 75231 Pa^s Cedex 05 BHDOR signals have been observed on л refrigerated solution of the compound [ (C^HgJjUlBHli]- [H»-l8-crow»-6J* in deuterated tetrahydrofuranne. Depending on the applied eagnetlc field, the orientation of Molecules for which signals are observed is selected. These signals are ascribed to the protons of the cyclopantadieryJ And borohydride noieties. They show that the coupling of the ur paired electrons 0" uranium (configuration 5th is predominantly of the Femi contact type. THE STRENGTH OP CHBMIOAb BONDS ?OHHED BY ШШШЩ I ^g IN OfCLOPBHTADIENH. OOUPOUHDS MOM THBBMOOHEHIOAL DATA I— V.L.Telnoy, U.R.Leonov, V.N.Larina, G.V.Solov'yova. Chemistry Research Institute of Gorky State University, Gorky, USSR It la neoescary to determine thermochemical parameters of uranium con taining compounds for tbe choice of optimal conditions of the processes with participation of the above oubeteaoes and studying the strength and nature of chemioal bonds in the eubstauoes. Enthalpies of oombustlon (&0H°) for a number of oyclopentadienyluranlum compounds «ere first measured and from these values enthalpies of formation (Ix^R") is oryatalllne (o) and gaseous (g) states as well as average dis ruption enthalpies of several bonds (B> ware calculated (in Table). Xhermochemloal Data of Compounds Studied (kJ/ool.; 298,15 Ю Compound -Д.0Я°(о) 4. jH«(o) AfH'fg) Bond 5 t - 1 Л О 255+12 о..с_н5 <°5V4u,o 50+25 U-01 (05Hs)3TI01,c (OjHjljOi-o^.c 138+29 u-i-o4H9 (CjH^jlTOn-C^j.o ГО h » t o - -310+21 U-n-O.Hg \m The total content of impurities In the samples studied did not exceed 0.1 mol.X for tetraoyolopentadlenyluranlum and 0.5 mol.% for other coo- pounds. The enthalpies of combustion were measured In a calorimeter 7-06 with a static c&lorlmetric bomb. Aside from HgO (1) and C0„ (g) crystal line oxide, UjOg, was a combustion produot. The calculation of .(U-R), where R - CI, i-C.H„, On-C.Hg, was carried out by the expressiont 5(D-R) -Д^Н°«Г,Е) + 3 ijH°(05H5,g) +AfH»(R,g) - AfH^tC H ),-UH,g7 - The experimental and literature values of Ъ were discussed to ascertain regularities of their dependence on the element location in the Periodic table and the nature of radical linked with It. 704 САШЙК1ЛТ10Н, CAHBOHLAMON, ОППАИОН REACTION AGS THERMAL |"T49~ DECOMPOSITION 0? TETSABBHMLURAlIIUIt M.R.Leonov, V.A.Il'yushenlrov, G.V.Solov'yova. Chemistry Rasaaroh Institute of Gorky State University, Gorky, USSR It ma found that tetraDenzyluranium (TBU), Bz.U'HgClg, interacts with CO(343K,30h) and COg(298K,15h) in benzene «olutio'n with th« abaorptlon of only 1 mole of CO at an excess of latter, 1 or 4 moleo of C02 depending en the ratio of TBU and gas (1i1,1i4,1:6). The migration lnaertlon of gas mole cules la shown to occur into (Г-bond of uranium-carbon. IR apeotra of newly formed complexes enow an abaorptlon band 1625 on assigned to aoyl (I) or absorption bands 1610 and 1395 em whioh are characteristics of carboxy- lates (II). A main produet of alooholysie of I ia phenylaeeialdehy&e and II- phenylaoetic acid. At 49ЭК I and II decompose with the formation of pnenyl- aeetaldebyde, dibenzyl and other produots of llgand transformations. The complexes of uranium are dimerlo In benzene solution, in the solid state the degree of association for I Increases upto 4 and for II - to 4 or 8 (TBITsOOg a 1.1,1;4). At 298K TBU Is oxidised both by molecular oxygen sod tert-butyl hydroper oxide (III). In the first case the complex Bz2U(0Bz)24lgCl2 Is formed In ethylbenzene in 30s, and those absorbs 0.5 mole of Og. Mono- and trlbenzyl- oxy-derlvatives of U as well as toluene are observed in reaction produots. On reaotlng with the excess of III in dloxane the following ooapounds are formed: BzUOj-HgClg'SHjO, Bu OH, BiOBu*, ИеСОИе, PhCHO and others. The me chanisms of oxidation reaction the initial stage of whloh is. In both oases, the oxygen Insertion into an uranlum-aarbon bond is suggested. According to OTA results between 293 and 773K TBU begins to deoompose at Э6ЭК. At the first stage, accompanied with exothermal effect at 563K. 12$ of the mass is lost, the total mass loss being 35$. The nonvolatile residue contains (5b U 62.25; Mg 4.55; С 6.00» H 2.50; CI 19.70. On TBU decomposit ion under dynamic conditions (vacuum, 293-643K) the produots Isolated in- olude (&, mass)t solid volatile! (8.6), liquids (19.6) and gases (0.3). From the temperature Interval distribution their composition la following; toluene, benzene, ethylene, propylene, methane, hydrogen from 293 to 449K; ethylbensene releases between 449 and 573K; dlbenayl, styrene ols- and trans» stllbanes, dlphenylmathane, hydrogen and methane in range of 573-673K. The experimental results point to the homolytioal mechanism of the pro cess and the catalytic Influence of metals formed or its carbide. 205 PHOT0FISS1ON OF NEPTUNIU|l-237 INDUCED BY BREMSSTRAHRUNG OF 25.1 4 30, and 40MeV I " T.Mitsugashira, H.Yagi. S.Suzuki*. H.Hirayama". H.Takahashi" Institute for Materials Research. Tohoku University. Sendai 980, Japan *Japan Radioisotope Association Takizawa Laboratory. Takizawa-mura. Iwate 020-01 Japan **NAIG Research Laboratory, Nippon Atonic Industry Group Го..Ltd.. Kawasaki 210. Japan In order to study fundamentally the photofission on S3'Np. highly purified z3,Np targets were irradiated with brensstrahrung of the maximum energies between 25 and 40MeV.The target was prepared by elect rolysis using an isopropanol solution on an aluminas foil and then enclosed in a quartz tube for irradiation. All irradiations were carried out using the Electron Linear Accelerator of Tohoku University The linac was operated at electron energies of 25KeV. 30MeV. and 40UeV with the bean pulse width of Зд sec, peak current around 100mA. and the pulse repetition rate of 300 sec"1. The quartz tube containing 337Np target was placed horizontally along with the central axisis of the breiisstrahrung in close contact with the back of a platinum converter of 0.71 radiation length (2mm) and cooled by running tap water. The dose rates at the target position were measured by using the ,,7AU(T .n) IBTAu reaction and found to be 4.6x10". 5.7x10". and 1.3x10'* photons/cn'/sec at 25UeV. 30MeV.and 40HeV. respectively. Since neutrons produced through ( у .xn) reactions on the quartz tuba, aluminum backing foil, and the target itself interfere in the present ?xperiments, the neutron flux in each energy was also measured by using the '9TAu(n.r )19SAu reaction and found to be about 5xlOT neutrons/cmVsec. From the above fact, it was proved that the fission contributed by such neutrons was negligibly small. Fission products were identified nondestructively by their у -rays using a high purity germanium detector coupled with a 4096ch pulse height analyzer. Disintegration rates of fission products at the end of irradiation -were determined from the counting rates of the observed r -ray peaks by usual r-ray spectrometric technique. The fission yields were calculated on the basis of the disintegration rates at the end of irradiation taking into accourt for the charge distribution of the relevant mass chains. The mass distribution in.each energy is shown in -Fig. I. In the figure, О indicates the data point obtained experimentally and the points shovn by О are mirror points obtained by assuming that the prompt neutrnns to be 2 in every fission event. 306 The yield ratio of 140Ba/M"Cd is considered to be the seasure of the peak to trough ratio of the «ass distribution. In Fig.2. the ratio obtained are shown as a function of electron energy* together with the values reported in references 1 and 2. It is obvious fro» Fig. 1 that tbe shape of sass distribution does not change significantly with the increase in the вахлшш energy of Ьгеаодtrahrung frou 25MeV to 40NeV. According to Rets. 1 and 2, tbe larger values of the peak to trough ratio, which indicates larger . contribur.ion of antisyaaaetric •-••-' • fission, are ?.pparent at the energy region below 2QMe'V. The peak to trough ratio is almost constant at the energy /\ region between 25 ~40MeV. This iuplys a7 \s that the photofissions of * Np is governed by fission froa the giant *& iU ifc i > resonance states. • This work О Ret. 1 and 2 V. КаНишп energy of bremsstrahluag r'ig.l.Hass distributions of fission Fie. 2,Peak to trough ratio of yields due to breHSBtrahrung the fission of **'Np due to irradiation on *"Np breasstrahrung irradiation References l.H.Ya.Kondra ко et al.. Sov.At.Energ. 53(1982} 164 2.H.Ya.Kondra ко et al.. Sov.At.Energ. 34(1973) 52 207 STEREOCHEMISTRY OP NEPTUHIUM(V) SULFATE AMU CARBOXYLASE 4-51 COORDINATION COHPOOHDS M.S.Grigoryev. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR The availability and stability of Hp(V) solid compounds make them suitable for the structural study of An(V) coordination compounds. Crystal and molecu lar structures were determined, IR, Mossbauer and optical electronic spectra were measured for the following JIp(V) compounds: (tlp0g)gS0.-2Hg0 (I), св3[дро2(804)г].гнго (ID, [co(jm3)6][]ipo2(so4)2] .гн,о (in), [со(мн3)6]н8о3 [Hjio2(so4)J (iv), HpOgOooH'HjO (v), spo2oooH (vi), Соо(ын3)Д[Нро2(о2о4)г]- •nlUO (VII), Ир coordination polyhedron (Cp) is pentagonal bipyramid in all these compounds, the distances Np-0 are 161-192 pa (apical) and 239-256 pm (equatorial). Structure I ia constructed by square cation nets, in which every Np02 ion ia coordinated to two neighbour ones, the nets are linked by bridge SO. groups. Structures II and III are baaed on infinite [HpOgCsCOj*1 ~ chains (II) or ribbons (III), connected by cations and crystallization water molecules* In II neighbouring Up C? share one edge, the pairs of CP are linked into chains by bridge 30, groups. In anionic ribbons of III Ир CJ? are isolated. IV contains 10 dimeric centroeymmetric complex anions {[Hp02(SO,)J2} ", in which HpO„ groups are bonded to each other with bridge SO. groups. 0 atoms of Np02 groups possibly participate in H-bonds with HjO (III) (276 pm) and 1Ц0 (IV)' (237 pm). In formates, as well as in the simple sulfate, every Hp02 cation is coor dinated to two neighbour ones forming in V square cation nets, similar to I, and. in VI - a three-dimensional net of diamond type. The transition to diamond net is connected with the rearrangement of atoms in the equatorial plane of Яр СР. The bridge formate ions in V link the NpO* cations of the seme net, the neighbouring nets are oonnected with H-bonds. Oation-cation (CC) interaction of KpOg ions plays the essential role in the formation of structures I, V, and VI. Np-0 distances in Hp02 are longer if 0 atoms are Included into the coordination sphere of another Np atom. In the equatorial plane the dlstanoes from Dp to coordinated 0 atoms of Np02 groups are practioally the same or sometimes shorter than to 0 atoms of other Uganda, i.e. the strength of 00 bonds is comparable with the strength of HpO* coordi nation bonds with neutral and acidic ligands. In V and VI formate ions link only Bp atoms, connected with CC bonds, therefore the CO interaction may be considered as decisive factor in these structures. Square nets of Hpo£ ions, similar to observed in I and V, can be the base of many structures of Np(V) "coordination deficient" compounds, while diamond (VI) and NDO (unobserved) type nets oan exist only in very simple ootnpounds. She analysis of IR spectra of Np(Y) compounds with known structure shows, that CC coordination results in the shift of UpoJ antisymmetric stretching vibrations band to lower frequency, The effect of CC interactions can be ob served as well in other spectroscopic data. For Mossbauer spectra of Hp(V) compocnde with CC coordination hyperflne magnetie splitting is characteristic. In Au(Y) compounds CO interaction plays probably smaller role, that exp lains noniaomorphiam of many Am(v) and Hp(V) compounds of similar composition. 208 MEW RESULTS OP THE STUDY OP PIHSIOO-CHEMICAL PROPERTIES OF SOMEl SLIGHTLY SOLUBLE COMPOUI1DS 0? ACTIHOIDS I . E. Ы. Pasuknin, A. S. Krivokhatskii, 3. M. Kochargin. Khlopin Radium Institute, Leningrad, USSR Solubility method baa been chosen for the study of slightly soluble compounds of some actinoide. She analysis of this method has shown that the available techniques for deteimination of solubility product of slightly soluble compounds are not reliable and have no sufficient foun dations. !Ше authors propose a new method for eolubility product determi nation using the analysis of solubility curve» Be eolubility data for oxalates and hydroxides of thorium, plutonium and americium are used as illustration of this technique. Theoretical analysis of stepwise complexation equilibrium in solution shows that the stability constant value (Ke) of complex species must be governed by special laws which are suggested as a criterion of selection for computer calculation* The etate of thorium, plutonium and americium in oxalate solutions and in solutions with high pH is considered as an example. The analysis of eolubility data for precipitate of thorium oxalate hexahydrate has shown that beginning with Borne oxalate ion concentration the shape of solubility curve changes. The theoretical analysis revealed that this phenomenon is explained not by solid phase composition change but by thorium polymerization in solution causing the formation of Th2(0x)|~ ion. Theoretical analysis of the process of hydroxide suspension precipi tation of radioactive substances has shown that this process can be devided into two stages: fast stage and slow one. The authors believe that the fast stage is determined by gravitational settling and the slow - by radiation "fluffing", and they confirm this for the cases of Pu(OH)4 and Am(OH).,. The interaction of heavy metals with oxigen-containing silicon compounds is studied poorly. The authors have not found the data on this interaction in literature. At the same time this problem is of great importance, silicon being present as an impurity in any chemical system. We have studied the complexation of Pu (IV) with sodium silicate using spectrophotometry. The value of Ke for the formed silicate complex has been determined. The product of interaction between sodium silicate and plutonium nitrate has been isolated in pure form. 14.3ак.1607 209 THERMAL DECOMPOSITION OF МЕРТШГ1СМ< IV) AND PLUTOKIUM(IIItIV) j 4_53 | OXALATES I ' A.I.Karelin, O.P.Lobas» V.A«Uatyukba, R.D.Kozlova, H.H.Krot. Polytechnical Institute, Tomsk, USSR To investigate the. process,the methodв of element chemical analysis,comp lex thermal analysis,7R-spectroscopy, spectrophotometry» gas chromotography were used. There have Ъееп considered the results of such investigations of hexe-and dihydrates of plutonium (IV) and neptunium (IV) oxalates, of deca - hydrate of plutoniura (III) oxalate, of products of isothermal hexahydrates decomposition and also of products of plutonium (IV) oxalate decomposition under the influence of its own radiation. According to the thermoanalyticai curves there have Ъееп defined: a number of processes stages,mass losses on each stage•the character of tempo effects, the temperatures of maximal processes development and temperature ranges of their going on under dynamic heating. The compositions of gas phases,extract ing under program heating of given compounds in inert and oxidizing atmos - pheres are settled with a chromatographic method* The temperature spectrum changes have been studied in 400-4200cm~ and 40O-730nm ranges.While consider ing recorded spectrum we watch the intensity and band width in the range of valent oscillations of HpO,CO.The carbonates presence was settled according to the presence of absorption band of 860cm~ .The process of reduction of plu- tonium(IV) to plutonium (III) was watched on duplet changes of the oxalate curve in 1300 cm range and on changes of characteristic maximum of pluto - ni.um (IV) and plutonium (III) absorption in 400 - 730 nm range. The comparison of all experimental data made it possible to offer a probab le mechanism of decomposition of neptunium (IV) oxalate hexahydrate, to de - fine more exactly a described in the literature mechanism of dehydration and thermal decomposition of plutonium (IV) oxalate, to confirm, that during the process of thermal and radiolytical decomposition the reduction of plutonium (IV) to plutonium (III) and carbonates forming take place. In neptunium (IV) oxalate case dehydration processes may be represented by the following scheme: нр(о2о4)г- бнго §2E2 нр(ого4)2- гнго + 4Нгэ, иР(с2о4)г.гнго1^-5^(ого4>2.нго • н2о, нР(о2о4)г- HgO suJJs нр(оао4)2- нго. Under further raising of the temperature there takes place a decomposition of neptunium (IV) oxalate to Hp02 with forming of an intermediate product con taining till 85i5 of neptunium (V) oxalate. The mechanism of thermal decomposition of plutonium (IV) oxalate may be represented oy the following sequence of reactions: Ри(о2о4)г-баго -2532 PU(O2O4)2. гн2о + 4*1,0, pu(o2o4)2. гнго И^Ё PU(O2O4)2- нго+ нго, 2 4гг ч . ы^г°^г/2 * "г0 + сог» Fu(cao4)2 -222f£ p„o2 + гсо + 2со2, PU(O2O4)3/2+ ог3222ё риооо3+ 2оог , 00 80 0 PuOOOj З -? " . Ри02 + СОг 210 SUBLIMATION STUDIES OF NpF4 AND NpOiF2 4-54 P. D. Kleinschmidt, Las Alamos National Laboratory, Los Alamos, NM 87545. USA K. H. Lau and D. L. Hildenbrand, SRI International 333 Ravenswood Avenue, Menlo Park, CA 94025-3493, USA Samples of NpF4 and NPO2P2 were sublimed in a Knudsen effusion mass spectrometer. The fallowing reactions were observed to occur: NpF4(s) = NpF4 2Np02F2(s) = NpQ2(s) + NpF4(g) + 02(g). (2.) The starting materials were identified by Debye-Scherrer X-ray power diffraction as was the solid product in reaction 2. Ionization and fragmentio n appearance potentials identified the vapor species as NpF4(g). The ion intensity of NpF3+'NP%was measured as a function of temperature for both reactions. For reaction 1 the temperature range covered was 817 to 979 K. The enthalpy of sublimation was 274.1 ± 3.3 kj mole and the entropy of sublimation was 176.1 ±3.8 J/K mole at 909 K. For reaction 2 the temperature range covered was 841 to 969 K. The enthalpy of decomposition is 559. ± 14. kj/mole and the entropy- of decomposition is 342. ± 16. J/K mole at 901K. Derived thermochemical quantities at 298 К are: the enthalpy of sublimation of NpFj(s), 285.3 ± 3.3 kj/mole; the entrppy of sublimation, 1962 ± 3.8 J/K mole, the enthalpy of formation of NpF4(g), -1590. ± П. Ы mole; the entropy of NpF4(g), 348.9 ± 7.9 J/K mole; the enthalpy of formation of NpOjF2(s), -1615 ± 9. kj/mole; and the entropy of NpOzF2(s), 136.4 ± 8.8 J/K mole. The measured entropy of NpF4(g) indicates that it has a tetrabedral structure. Chudinov and Choporov[l.] measured an enthalpy of sublimation of 317.1 ± 2.3 kJ/mofc t'Jd an entropy ofsubmnaaaaof210i95.9J/Kffioleforreaction 1. This data indicates that NpF4(g) has a C2v structure. Studies by Hildenbrand and Lau[2.]*and by Smimov and Gorokov[3.] on the decomposition of U02F2(s) show that it sublimes to give UChF2(g),UF3(g). UF4(g), and UOF4(g). but studies by Lau and Hildenbrand [4.] on the decomposition of ThOF2(s) show that it sublimes congruently to ThF4(g) and THOj(s). The evidence here shows that Np02F2(s) sublimes like TbOFz(s) rather than U02F2(s). References 1. EG. Chudinov and D.Y. Choporav^Radiolthiraiya 12, pp. 525-7 (1970); Sov. Radiochem. 12, pp. 490 (1970). 2. K. H. Lau, R. D. Brittain, and D. L. HUdenbrand/t. Phys. Chem. 89, pp. 4369-73 (1985). 3 V. K. Smimov ;nd L, N. Gorokov^Zh, Fiz. Khim. 58, pp 572-6 (1984); Russian Journal of Physical Chemistry 58(3), pp. 346-9 (1984). 4. К. Н, Lau and D. L. Hildenbrand, submitted to J. Phys. Chem (1988). 211 MULTIPLE MARTENSITIC TRANSFORMATIONS. mCOHKEKSURATE/COMHEHSURATE PHASES AND CKARCE- DENSITY-HAVE STATES IN PLUTONIUM HETAL: THEIR CONSEQJJEHCES | 4-54-55 T. A. Sandenav and J. F. Andrew, Los Alamos National Laboratory, P.O. Box 1643, HS E511, Los Alamos, KK 87545 USA Sandenaw1'3 has recently suggested that transitions between commensurate charge-density- wave (CCDU) states and incommensurate chatge-denslty-wove (1CDW) states, or vice versa, are responsible for plutoniuo (Pu) metal behaviour In transformations between its phases. Andrew3 has recently made simultaneous aeasurenents of elongation, electrical resistivity and temperature on Pu metal between 200°C (473K) and 450°C (723K). The upper limit of his measurements was well into the delta-phase range. His results suggest two (2) martenslcic transformations in the temperature range between 300K and 62ЭК because of hysteresis loops observed, particularly in the electrical resistivity vs temperature curve. The resistivity loops se&n between heating and cooling cycles are like the classic loops seen with Au-49% Cd and Fe-Ni <70;30) alloys. There was only one single long hysteresis loop seen in the elongation data. It was between the alph-Pu and delta-Fa phases.3 Sandenaw''9 had previously suggested chat there was a martens!tic transformation in the alpha phase range of Pu below room temperature with an Hs temperature of -100K And an Mf temperature of -60K. The low-temperature resistivity curve was similar to those of HIT! nlloys. Evidence thus suggests three martensItiс transformations in Pu between OK and 723K, with a different basic electronic behavior through each of the postulated martensltlc regions, The results of Andrew3 suggest a tie in between CDU states and martersicic transformations in Pu metal. This has already been done for Tijg Ni4? Faj by Huang, Meichle, Salamon and Uayman*a'b and is discussed in references 1 and 2. Goldberg and Hassalr.Vi5 have reviewed tile evidence for martensltlc transformations between phases in Pu metal in thalr 1970 paper and have referenced the papers of many experimentalists. Although mortensitic transformations were suspected, the range of each of two transformations was not evident nor an apparent overlap of the two at -16SaC (A38K) until Andrew's definitive experiment. We will present evidence that the effects of such multiple martensItic transformations with Pu netal permit s £-pbass skip and, by a double martensitlc transformation under sone condition of purity and processing, permits a direct delta phase to alpha phflse transformation. He will present arguments for a continuous change in f bonding or f-d hybridization from near absolute zero to the epsilon phase of Pu, and the uniqueness of the gamma phase. References 1. T. A. Sandenaw. Los Alamos National Laboratory report LA-11083-HS (March 198S). 2. T. A. Santlenav, Phase Transitions, (to be published 1989). 3. J. F. Andrew, original research, Materials Science Technology Division, Los Alamos national Laboratory, Los Alamos. HK 07545 USA (1988). ba,b. С. н. Hwang, H. Kelchle, К. В. Salamon and С. M. Uayraan, Phil.. JMag^ 47/1983/9 And Phil. Над. 47/1983/31. 5. A. Goldberg and T. B. Massalski. Plutonium 1970 and Other Aetlnides. Vol. 17, Part II. U. N. Hiner, ed.. The Metallurgical Soc, * T.H.E.. Hew York (1970) p. 87*. 2*2 1ИР1ЛЕН0Е OF ROOK TEsTERATORB SELF-IRRADIATION OH CRYSTAL 4-56 STRUCTURES OP PUjOa, AND J\>-PuOaj COHPOUKDS ll.A.Andriancv, N. T.Chebotarev, All-Union Research Institute of Inorganic Materials, Moscow, USSR Changes in the crystal lattioe parameters and unit oell volume were in vestigated for PUi-Gaj (tetragonal structure of the W^Slj type, a • 11.747 A, с - 5.503 A) and fi -PulSa, (hexagonal structure of the MgjCd type; a • 6.299 A, e a 4.512 A) as effected by the room temperature self-irradiation for 650 and 1040 days, respectively. The causes of the changes were analysed. As a result of the self-irradiation the lattice parameter a of Pu^Ga^ deoreaced by 0.37* while the parameter o. inoreased by 0.29*. The unit cell volume decreased Ъу 0*46%. The lattice parameter a of Д-PuGa, decreased Ъу 0.30*, while the para meter £ Increased by 1.15*, in this case the unit oell volume increased by 0.54*. Changes In the crystal structure of Pu-Ga- having no allotropie transfor mations are shown to be mainly due to a vacancy accumulation ( ~ 1$) in the compound structure. However, structural changes in the Ji -modifloation of PuGa» that is stable at room temperature are essentially related to a decreased compact ness of the atom peeking as due to small displacements of atoms in the struc ture of Q-PuGa- that bring it oloser to the structure of the low tempera ture modification, «<-PuGa,, having a rhombohedral lattice. THE HOMOGENEOUS GAS PHASE REDUCTION OF PLUTONIUM 4-57] HBXAFLUORIDE BY METHANE George и. Campbell Los Alamos national Laboratory, Los Alamos, Hew Mexico 87545 USA Plutonium haxafluorlde is an intermediate product of a separation and purification process. While it can be reduced fro» the gaseous hexafluoride to the solid tetrafluoride by heating, it is often Bore convenient to use a chemical reducing agent. Methane gas has been found to be an ideal reducing agent. The small temperature coefficient of the reaction insures that control can be maintained over the reaction rate. Reaction rates near room temperature have been measured. All products with the exception of Plutonium tetrafluoride remain in tlm gaseous state and are easily separated. 213 RADIOLYSIS О? PLUTOHXUH HEIAFLUORIDE PHYSICALLY 4-5S ADSORBED ON Pu?4 I.Yu.Mereev, V.N.Prusakov, v.F.Serik Kurchatov Institute of Atomio Soergy, HOBCOW, USSR The study of radlolysis of adsorbed PuFg supplements the investigations with PuPg in the solid and gaseous states. Some properties of the PuFg mo nolayer (for example, the deactivation rate of exoited molecules, the proba bility of recombination, etc) are intermediate between the above states. The experiments were carried out at a temperature of (293±3)K and equi librium pressures of PuPg between 2.0 and 10.0 Torr, with the surface cove rage of the starting FuF. covering the range of 0.62*0.04 to G.84-0.04. The rate of radiation reduction of PuFg detemined from the increase in mass of FuF, during the experiments proved to be (2.3-0.2) wt.jf per day and indepen dent of the surface «overage within the experimental error. The ease quan tity for solid PuFg with the same ieotoplo composition was equal (1.6 * 0.1) wt.it per day. The calculated flux of alpha-particles through the layer of FuFg adsorbed on PuF> is 1.25 times as high as in any cross-section of Bolld PuFg, therefore on condition that the radiation chemical transformations oc curring in the adsorbed and solid PuFg are constant the reduction rate for the PuFg monolayer is bound to be (2.С - 0.1) wt.S per day. That the avera ge value experimentally observed exceeds the above value ±в attributed to the lower efficiency of recombination and deactivation in adsorbed PuFg as compared with solid plutonium hexafluoride * 214 PREPARATION OP RARE METALLIC ACTINIDES (2*8Cm.249 £k, 249Cf) 4-59 AND INVESTIGATION OP THEIR CRYSTALLINE STRUCTURE A.G.Seleznyov, V.M.fiadchenko, V.D.Simshakov, M.A.Ryabinin, P.P.Droanik, L.S.Lebedeve, V.Yft.Veailyev, Research Institute of Atomic Reactors» Dimltrovgrad, USSR _ ЗЛЯ 7ЛЧ ">ЛЧ Rareactini.de metals on the basis of Cm» Sk and "Cf-nuclides were directly reduced from their oxides with subsequent vacuum distilla tion. The initial Bk and Cf-samples were subjected to preliminary cleaning by extraction-chroraatographyt Cm-sample didn t run through such cleaning* cm» Bk and Cf-oxides were prepared through oxalate, beintungsten (for Cm) and tantalum (for Bit, cf) crucibles with metal vapor condensation on the tantalum (for Cm,Bk), quartz and ceramic (for Cf) substrates. Equipment for reduction-distillation is shown in the Pigure, Metal Reduction Conditions and Lattice Constants of their * -Phase 248, Cm r a m e t e r Sample 1 Sample 2' Sample mass in the crucible, rag 1.08 - 1.03 1.54 Reducing agent(excess,multiplicity) Th(16) - Th<18) Ia(25) Crucible temperature at the bottom,°C 1850 1600 1720 1340 Time of heating, min 3 5 7 22 Metal yield on the substrate, год 0.98 0.94 0.74 J, 71 Yield,•% from the initial mass 91 S3 72 46 Total yield, % from the initial mass - 99 B5 34 Amount of basic impurities; - in the initial sample, % 9.7 - in metal, % 0.6 Thickness of the layer on substra te, f з.о dhcp constants 3.520(1) 3.486(1) 3.412(1) 3.380(2) lattice 11.396(1) 11.297(1) 11.060(2) 11.025(2) of it -puase e/2a 1.619(1) 1.620(1) 1.621(2) 1.631(1) x -obtained by vacuum distillation of the sample 21S The samples were investigated by x-ray diffraction at room temperature and at T * 93 - 300 K. For all samples a dhcp structure was determined defi nitively r which is stable under normal conditions. The lattice constants decrease from cm to Cf (actinide contraction). It was shown that La, у and Рг-impurities, dissolving in u. -Cm lattice, caused an increase of Its con stants (data in the table presented for samples 1 and 2). For the first time a fee lattice of curium high-temperature modification ( JS -cm) with the constant a % 4.933 A was revealed, which doesn't change by rapid cooling of the fine film sample up to the room temperature, but it disappears as a result of its low-temperature treatment. Oxidation of the prepared metals was investigated under various condi tions. Сто or Cm(0,N) fee lattice is formed comparatively easy by metal vapor condensation in vacuum and doesn't change by cooling or low-tempera ture treatment of the sample. вкО-lattice was revealed only after sample annealing at T = 600°C in vacuum, as for cf the similar phase wasn't found at all. Thus, decrease of transplutonium elements monooxide stability along the actinlde series (from Am to Cf) was observed. Temper at-jre coefficients of thermal expansion for «*, -Cm and *L -Bk w«re determined by x-ray technique at the temperature "J3 - ЗОО K(©£av =(10.1 6 1 6 ±1.3}»10" X" and oiav ={13.1 +1.4)-10" K""', respectively) * The comparison of the obtained data with those presented in literature was aimed at determination of regularities for property changes of actinide metals along the series. Or"» Equipment for preparation of metallic 248Cm(a), 24SBk(b) and 249Cf(c)j 1 - a mixed pellet of actinide oxide and reducing agent; 2 - evaporating crucible] 3 * condensing substratef 4 - cooper water-cooled support rodi S - RF inductori 6 - heater; 7 - sealed quartz flaskjO -ceramic support rod? 9 - liquid nitrogen; 10 - nozzle MAGNETIC BEHAVIOR OF CURIUM AND AMERICIUM-CURIUM ALLOYS* | 4^g. S. E. Nave"'b, R. G- Haire" and J. R. Moore*'b 'Department of Physics, university of Tennessee, Knoxville, Tennessee 37996-1200, USA transuranium Research Laboratory, chemistry Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6375, USA The transplutonium metals, curiumtl], berkelium[2], and californium(3), have been shown to have localized t-electron configurations analogous to the lanthanide metals by virtue of their local magnetic moments. As in the lanthanide metals these local moments strongly interact and form an ordered magnetic state with transition temperatures as high as 65 к. In metals the magnetic interactions result from the interplay between a short-range force due to wavefunction overlap (direct exchange) and a long-range force via the conduction electrons (the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction), Magnetic interactions in the lanthanide metals and alloys appear to be dominated by the RKKY mechanism as indicated by the long-range sinusoidal spin structures in the ordered state observed in neutron diffraction experiments. A useful way to study the interplay between these two mechanisms is to study the effects of dilution of the magnetic lanthanide with a nonmagnetic metal of similar electronic properties such as La, Sc, or Y. For curium a good choice for the diluent is the nonmagnetic transplutonium metal, americiunu Americium has the same dhcp crystal structure as curium and a nearly identical metallic radius. Thus it should provide a minimum perturbation of the curium conduction band. Americium is nonmagnetic since it has a J=o, 5f6 electronic configuration and magnetic measurements on the metal have confirmed its zero paramagnetic moment. The experimental susceptibility was temperature independent except near 4 K, where there was a sharp upturn attributed to a paramagnetic impurity[4]. Magnetic measurements on 2**Cm metal have indicated a maximum in the susceptibility at 65 K[i], while neutron diffraction measurements on a polycrystal of 2**Cm metal have revealed a simple antiferxomagnetic ordering with T„ of 55 K[5]. Above this temperature it exhibits a Curie-Weiss region with fitti of 7.6 fiB and 0P of 259 K. Three compositions of Am-Cm alloys were prepared for this study: 20, 50, and 70 at% Am. The specific objective of this work was to determine the type of ordering and ordering temperature of the magnetic transition as a function of alloy composition. In all three alloys there was significant field dependence of the susceptibility up to temperatures as high as 300 K, which made the determination of effective paramagnetic moments and Curie temperatures inaccurate. However, this field dependence does not significantly effect the conclusions about the low temperature ordering in the alloy». Spark-source mass spectroscopic analysis did not reveal the presence of magnetic impurities in amounts sufficient to account for this effect. The results of the magnetic measurements are given in the figure as a plot of inverse molar susceptibility versus temperature; the data for pure curium metal are included for comparison. The low temperature transitions were very broad for the 50 and 70% alloys and this made the assignment of transition temperatures very difficult. The qualitative conclusions reached are that the antiferromagnetic transition is 217 100 i т , г , г о I i I I 1 1 1 1 0 90 100 150 200 250 300 350 Temperature (К) Inverse Susceptibility versus Temperature for Curium And Curiut.-ABerici.un Alloys depressed to к 55 К for the 20 at% (americium} alloy and to below = зо к for the 50 and 79 at* alloys. The effective paramagnetic moments are in reasonable agreement with that of the pure metal as indicated by the similar slopes of the straight line regions (Curie-Weiss regions). This behavior is in marked contrast to* that of curium's lantbanide homologue, gadolinium, which h? s a ferromagnetic transition at 293 к in the pure metal. For Gd the transition temperature is also depressed with increasing dilution by Y, Sc or La. However, a point is reached where the ordered state changes to a complex antiferromagnetic type[6]. These differences in beh&vior suggest that direct exchange may be more important in the transplutoniura metals and their alloys. The broadening of the transition for the curium allays may also be important and further experiments such as specific heat measurements are needed to investigate this effect. Research sponsored by the Division of Chemical Sciences, Office of Basic Energy Sciences, U.S. Department of Energy in part under grant DE-FGQ5-88- ERX3834 to the University of Tennessee, Knoxville and in part under contract DE-AC05-84ER214OO with Martin Marietta Energy Systems, Inc. References 1. Huray, Paul G. ; Have, S.E. ; Handbook on che Physics and Chemistry of che Actinides; Freeman, A.J.; Lander, G.H.; Eds.; Korth-Holland: Amsterdam, 1987; Vol. 5, 311. 2. Nave, S.E.; Huray,, P.G.; Halre, R.G.; Crystalline Electric Field and Spmctural Effects In £• Electron Systems} Crow, J. j Guertin, R.P; Mihalisin, Т., Eds.; Plenum: New York, 1980; 269. 3. Have, S.E.; Moore, J.R.; Spaar, N.T.; Haire, R.G.; Huray, P.G.; Physic* 198S; ВХЭ0, 225. 4. Brodsky, M.B. ttore Earths and Acttnides; Inst, of Phys.; London and Bristol, 1971; Conf. Dig. £e. 3; 75. 5. Fournier, J.-M.; Blaise, A.; Muller.W: Spirlet, J.-C; Phvsiea 1977; В8в-Вв, 30. 6. Cogblin, В.; The Electronic Structure ?f Rare-Earth Hetals and Alloys: the Magnetic Heavy JEare-£ercn«; Academic Press Inc.:Londan, 1977; 35. 218 INTh'RNETALLIDES AMD ALLOYS OF TRANSPLUTONIUM ELEMENTH WITH METALS OP PLATINUM GROUP DEfD V.M.Radchenko, A.C.Seleanyov, V.D.U.ushakov, R.R.Droznik»M.A.Ryabinin, L.s.Lebedeva, V.Ya.Vasilyev. Research Institute of Atomic Reactore, Dimitrovgrad, USSR Americium and curium alloys with palladium and platinum,containing up to 20% of actinide,were prepared by coupled reduction.The obtained alloys were investigated by x-ray diffraction, differential-thermal , metallographic and chemical techniques. Formation of americium and curium solid solutions in palladium (up to 10-12% of act^nide) and eutectic character of interaction between them and the first from Pd-side РДэАт and РдзСт- intermetallides with fee structure were found in Pd-An - system.Concentration boundaries of the region were determined where these intermetallides existed.phase diagrams for Pd-Am (Fig.1) and Pd-Cm have been constructed. In the Pt-An system no solubility of дщ and Cm in Pt - fee lattice was revealed.The interaction between platinum and the nearest inter metallides, ptsAm and PtsCm,was found to be eutoctic.Phase diagrams for Pt-Am (Fig.2) and Pt-Cm have been constructed. The investigations carried out showed that PtsAn intermetallides (An= 243Ат,244Ст,249вк,249 Cf), obtained *s a thin layer on the surface of Pt- subsbrates, had hexagonal structure of CugC'a - type. Self-irradiation effect,caused by intensive nuclide decay of trans- Plutonium elements, on crystalline structure of the obtained intermetal lides was investigated.In particular,complete x-ray amorphization of PtsCm and Pt^cf crystalline structure was revealed(after they had been kept at room temperature for 5 and 70 days, respectively) .The pmeress was followed by increase of the unit cell volume,which by the moment of disappearance of reflections has increased by about ifc.ptgCm crystal line structure recovered completely after annealing at the temperature higher than 4O0°c. The crystalline lattice parameters and unit cell volume of Pt5Bk- intermetallide were found to increase due to accumulation of daughter- Ci with corresponding increase of <* - activity of the sample.The samples having been kept for 140 days,the cell volume increased by O.S%. Alloys of Bk with .iridium and rhodium were obtained as thin layers on the surfaces of iridium and rhodium substrates by coupled reduction. x-ray structural examinations showed that Rh3Bk-intermetallide with cubic lattice Df Cu3Au- type with a=(0.4013±0.0001)nm is formed in the Bk-Rh system and Ir2Bk - intermetallide with fee lattice of Cu2Mg- type with 219 a » [0.75204 * 0.0003)шп is formed in the Bk-Ir-syetem. The calculated maximal solubility of berkellura in rhodium was (0*5 * 0.2)%. The crystalline lattice parameters and volume of unit cells of Rh3Bk- and I^Bk- intermetallides were found to increase after they had been kept at room temperature for 45 days, that could be caused by irradiation damage of the 249 structure due to o*- - decay of Cf accumulated as a result of jb~ decay «&> ^f' 4 -?r •a am t e-M «-M+MjAm IMjAm m • — -_1 1_ ._ 1 к .А Am,% ?ig.1. Pd-Am phase diagram Pig.2. Pt-Am phase diagram THE INFLUENCE Off SELF-IRRADIATION ON THE STRUCTURE OP THE AMERICIUM ] INTERMETALLICS I4 " 2 I V.v. Ivanov, I.B. Popov. Institute of Physical Chemistry of tbe Acadeay of Sciences of tbe USSR, Moscow, USSR Self-irradiation of alpha-radioactive materials can brine to tbe change of a crystalline structure, in particular to the aaorphisation process of в com pound due to the action of reooil nuclei. It la obvious, that tbis phenomenon is of common character and it ia characteristic for many crystalline compounds of aetlnides* Due to tbis fact» tbe study of tbe influence of self-irradiati on on the properties of intermetallics of alpha-radioactive elements is of some interest, as, first, tbeae compounds in tbe dependence on tbe compositi on» have the structures of practically all main types and, second, they are not Influenced by the cbarge phenomena, causing the destroy of dielectric radioactive materials. In tbe present work tbe influence of self-irradiation on tbe aaorpbiaeti- on rate of intermetallies of smericlum-241 with nickel has been stuOled. The samples represent a composite of two compounds as AmNl and АдНЦ, obtained as a result of annealing of an X-ray amorphous compound AmNig. The internetallica under study have a rhombic structure of a T1Y type in the spatial group Gaca and a rhombohedric structure of a PuNi? type in a spatial group Ичщ , respec tively* The Table shows a change of tbe intensity in time of some reflexes of tbe AmHi^ compound* As for tbe AmNl compound, the decrease of intensity of Its reflexes haa not been noticed during 100 days, in spite of the fact that its specific activity is by three times higher at the same nature of a chemical bond. Relative Intensity of Reflexes of Intermetallic &mNi. nkl Time . bour I 3 50 90 1«0 200 500 1000 018 1.0 0.85 0.5 0 116 1.0 o.s 0.6 о.э 0.2 0 119 1.0 1.0 0.5 0.4 0 00.27 1.0 1.0 0.6 0.5 0.45 0 10.19 1.0 0.6 0.5 0.4 0.Э 0 309 1.0 0.95 0.55 0.45 0.4 0.35 0.15 217 1.0 0.85 0.3 0.3 0 It follow», that the Influence of self-irradiation on the structure of alpha-radioactive materials can be determined nainly by the type of a crystal line lattice. It is probable, that at transference of recoil nuclei (atoas) in a plastic substance the appearanoe of tbe deffects of vacancies or intro duction brings to deforaation of its crystalline structure (the structure of а Т1Г type is a plastic one). In hard structures the appearanoe of the ease 221 defects causes their decay» The following explanation is possible: in case of a rhombobedric syngonia its local reduction is difficult, but in ease of rhombic syngonia this fact takes place. As it is seen from the Table in the AmNl, lntermetallic compound the dec rease of the rate of intensity of reflexes from different pistes differs con siderably. But it is clear, that under the influence of self-irradiation the amorphisation process takes place in the whole crystalline structure, but not the disappearance of reflection froa separate plates. The given compound trans- fen into the X-ray amorphous state (practically completely) during 500 hours approximately. It is probable, that the nearer order is preserved and the time of conplete amorpbisation can not be evaluated precisely using the ob tained data. This time should be in 3-5 times higher and equals to 2C00 houre approximately. In such case a simple calculation shows tbat one act of alpha decay brings to the destroy of one elementary cell of в crystal approximately (a parameter of a rhombohedric cell is a» 8.62 I; a parameter of a hexagonal cell is a» 5 X, density equals to 11.8 g/cm^). In the result of annealing,at 500-600 the AaNi~ compound, transferring to the amorphous state after self-irradiation, reduces its crystalline structure. The rate of its further amorphisation does not differ from that one, which was before the annealing. We have also studied the influence of the external alpha radiation oa the structure cf the neodiaiua intermetalllcs of the same composition and the sa me type of a crystalline lattice. The energy of the external alpha radiation hae corresponded approximately to that one which is observed at self-irradia tion of intsrmetallics of Am. The results obtained show that the external alpha radiation does not influence the structure of intermetalllCB. In any case for the time, which is enough for the complete amorpbisation of the ame- ricium intermetallic (2000 hours), a noticeable change of the reflex intensi ty of the neodimiua interaetallic, being irradiated, has not been observed. From the facts described it follows, that the recoil nuclei make more consi derable influence on the structure of a compound, than the process of alpha radiation. THERMAL DECOMPOSITION OP TRANSPLUTOHIUW ELEMENTS OXALAT 4-63 | AND NITRATES BY DIFFERENTIAL THERMAL ANALYSIS V.I.Vaailyev, B.S.Kalevich, V.M.Radohenko, B.V»Shimbarev, y.P.Egunov, A.N.Izmalkov, V.Ya.Veallyev. Research Institute of Atomic Reaotora, Dimitrovgrad, USSR The DTA - 6D device for differential thermal analysis permitting to investigate samples 5-150 rag in mass within 20-ЮОО°С at beating rate of 0.01-3.0 °c/s in atmosphere of various gases was developed [l ] . Autonomous block with the Sample is located in glove box which makes it possible to study the thermal behaviour of actinlde element compounds with high specific radioactivity. An(III) (An=Am,Cm,Bk,Cf) Oxalates were obtained according to techniques |2„з], and Am(III) & Cm(IH) nitrates by the solution of the appropriate oxides in nitric acid (8 mol/lb The sample mass for DTA was 7-35 mg, the heating rate - 0.7 c/s. To achieve proper atmosphere prepurifled helium and oxygen were used. The composition of the final solid products of the thermal decomposi tion for An(III) compounds was determined by the X-ray phase analysis. As seen from Pig,1 , the An(III) oxa late dehidratation process is completed by 280°C regardless of the atmosphere in which the heating takes place,and with the further heating it has a great effect on decomposition character. In oxygen atmosphere Am(ili), Cm(III) and Cf(HI) oxalates decompose exothermically and the products of the decomposition of the first two compounds are Am02 and non- stoichiometric oxide Cm02_x {«(-form). In helium atmosphere the same oxalates de compose endothermically.As the result of Am(lII) and Cm(IIl) oxalates thermolysis the oxides of An0 composition are de 1 g Лл/ ^ rived. 200 400 TTC The DTA curve of the Bk(IIi) oxalate dif- боо feres from DTA curves of the other oxala Tig.1.DTA of ftm(III)(I), tes by exothermal peak at 295°C preceding Cm{III)(2), Cf(III)(3) and endothermical decomposition of dioxymono- Bk(III)(4) in atmosphere of carbonates. This effect is supposed to be oxygen(a) and helium(b) due to the oxidation of Bk(III) to Bk(IV) by the oxygen of the oxalate groups as in the case of Ce(III) salts thermolysis [4j.The product o£ thermal decomposition of Bk(iil) oxalate in helium atmosphere is non-stoichiometric berkeliura dioxide with lat tice parameter a*0.5347± o.0004 nm. 223 Decomposition nature oC hydrated nitrates Am(ill) and Cm(III) does not depend upon the atmosphere in which the heating is performed: in both oxygen and helium It occurs endothermically (Pig.2> and is О 200 400 бОО T.w Pig.2. DTA of Am(III)(a) Fig.3. DTA of CmCm) oxalate and Cm(lii)(b) nitrates in (1,2) and On (III)nitrate (3) atmosphere of oxygen (I) air-exposed fer 22 hrs (I), and helium (2) 160 hrs (2) and 48 hrs (3) completed with forming AmO, and non-stoichiometric Y.-phase of curium oxide. The values of the enthalpy of formation of anhydrous crystal line Am(in) and Cm(lll) nitrates evaluated from the DTA data are -64c and -700 kJ/mol respectively, 244 Data on the CmUII) oxalate and nitrate self-decomposition under the influence of inherent «^-radiation were obtained. Cm(lil) oxalate self-decomposes completely after exposure for 160 hours and nitrate - for 48 hours (Fi.g.3). References Hadcbenko V.M«, Eguaov V.P., lamalkov A.N., Vasilyev V.I. Preprint WIIAR-3<714). H.t ZNlIAtomlnform, 1987. Myasoedov B.p., Guseva L.I,, Lebedev I.A. et al. Analyticheskaya khlmiya transplutonievykh elementov. M.: Nauka, 1972. ЕПп E.A., Kopytov V.V., V&silyev V»Ya., Vltyutnev V.M.//Radiokhi- miya, 1977- Я.19. S.464. Puller M.J., Pinkatone M.//J.Le3s-Commoii Met. 1980. Vol.70. P.127- STRUCTURAL CHARACTERIZATION OF BERKELIUM AND CALIFORNIUM 4-64 OXALATES* O. E. Hohart and D. E. Morris. Isotope and Nuclear Chemistry Division, Los Alamos National Laboratory. Los Alamos, NM 87545 USA and G. M. Begunf, J. P. Youngf. and R. G. Hair«{, fAnalytical Chemistry Division and $Chen>istry Division, Transuranium Research Laboratory, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6375 USA The trivalent actinides are readily precipit",;ed from aqueous solution upon addition of oxalate ion, thus forming the sesqutoxalate complexes of general formula Апяохз-пНгО (ox = CaO*-). The quite low solubility of these compounds has been exploited for gravimetric determination, group separation, oxide preparation, and reprocessing of nuclear fuels. These complexes also serve as prototypes in the fundamental study of hard-oxygen-donor bonding to actinide metals. In this respect, these-oxalate com plexes are useful models for the study of structure and bonding in potentially important environmental species such as acttnide complexes containing carbonate ion or humic acid ligands. Several oxalate complexes of the lighter actinides (Th-Pu) in both the trivalent and the tetravalent oxidation states [2,2] as well as all the trivalent lanthanide oxalate complexes [3] have been isolated and characterized to varying degrees. The only oxalate complexes of the heavier actinides which have been studied to any extent are those of Am(lll) and Cm(lll) [4-6]. For the trivalent sesquioxalate complexes, М2охз-пНгО, the hydration number, n. can vary from 2 to 18. To some extent, the variation in this value is a manifestation of changes in the crystal and/or molecular structure predominantly attributable to changes in the metal-ion radius. Numerous studies of these important compounds have been made with the aim, in part, to establish a correlation between the hydration number and the structure [1-5]. These studies have utilized thermogravimetry and x-ray diffraction methods. However, other potentially useful methods of structural characterization, such as Raman spectroscopy, have not been employed. We have completed Raman spectral studies of the lanthanide oxalates [7] and we are currently studying the entire series of actinide (Th-Cf) oxalate complexes. We are employing Raman and solid- state absorption spectroscopies, in addition to the more conventional probes such as x-ray diffraction, to characterize more fully these complexes and address the question of hydration number versus crystal and molecular structure. In addition, we are exploring the more fundamental relationship between ^-element ionic radius and crystal and molecular structure. In this presentation we will describe our most recent results pertaining to Bk(lll) and Cf(lll) sesquioxalates. While the oxalate complexes of these two heavy actinides h?ve been known and exploited for some time, there are no known structural investigations of these two complexes. Berkelium and californium oxalates were prepared from the heavy elements provided by the High Flux Isotope Re- actor/Transplutorx'um Processing Plant under the (J.5- Department of Energy's Prop-am for Heavy Element Production. From a preliminary analysis of the x-ray powder diffraction data for the oxalates of both Bk(lil) and Cf(lll), it is clear that these complexes are isomorphous with the sesquioxalates of the lighter actinides, Pu(lll) and Am(lll), and the light lanthanides, La(lll) through Er(III). All of these latter complexes have been identified as decahydrates [1-5]. The structure type for these complexes is monodinic with space group P2i/c. This structure type for trivalent metal sesquioxalates is very specific to the decahydrates and allows us to conclude that the oxalates of Bk(lll) and Cf(lll) are also sesquioxalate decahydrates. " Research sponsored by the Division of Chemical Sciences, Office of Basic Energy Sciences, U. S. Departmert of Energy under contracts W-7405-ENG-36 with The University of California and DE- AC05-84OR21400 with Martin Marietta Energy Systems. Inc. Ь.Зак.1607 225 We have also obtained the solid-state absorption spectra of microgram samples of transparent crystalline Bk(lll) and Cf(lll) oxalates. The positions and relative intensities of the f-f electronic transitions in these spectra confirm that in both complexes the actinides are in the ttivalent oxidation state. Comparison of Raman spectra of th« lighter lanthanide and lighter act'inide oxalates with those of berkelium and californium oxalates confirms that the latter are indeed sesquioxalate decahydrates, which confirms the x-ray results mentioned above. Most of these Raman bands arise from vibrational modes that are predominantly localized on the oxalate ligands. However, the vibrational energies of many of these modes are influenced by the size of the t rival en t metal ion. In this way it is possible to deduce information regarding the structural effects of variations in metal ion radius. For the sesquioxalate decahydrates of the light tanthanides (La - Er), a linear increase in the energy of the most prominent Raman modes was found with decreasing ionic radius [7]. This trend does not app-ir to persist for the oxalate complexes of Bk(lll) and Cf(lll) ions. We have also obtained Raman data for i ^oxj-10 Hi О which indicate further that the vibrational energy versus ionic radius behavior observed for the lanthanides is apparently not retained for the trivalent actinides. This seemingly anomalous result is intriguing and determining the reasons for this behavior will remain a major focus of our ongoing work. References 1. I. L Jenkins, F. H. Moore, and M. J. Waterman, J. fnorg. Nud Chem. 27, 77-80 (1965). 2. I. L. Jenkins, F. H. Moore, and M. J, Waterman, J. Inorg. Nud. Chem. 27, 8X-87 (1965). 3. W. Ollendorff and F. Weigel./ло/£. Nud. Chem. Lets. 5, 263-269(1069) and references therein. 4. F. Weigel and N. ter Meer, faorg. Nud. Chem. Letts- 3, 403-408 (1967), 5. V. Scherer and M. Fochler, J. Inorg. Nud. Chem. 30. 1433-1437 (1968). 6. E. A. Smirnova, Ё. M. Pazukhm, A, S. Krrvokhatskir, and Yu. L. Pazukhina, Radhkhtmiya, 3Q 32-36 (1988). 7. D. E. Morris and D. E. Hobart, J. Raman Spectrosc. 19, 231-238 (1988). 226 COMPARATIVE STUD? OF KURCHATOVTDH АШ> ЕАРД1Ш BROHIDBS AND CHIORIDBS' 4-65 USING НШ THSMJOCHROIIATOGHAJHIO МЕШОЙ S.B.Iinolchin, Kim U Zin, V.P.UOmanov, Xu.T.Chuburxov, B.l.Zhuikov, K.A.Gavrllov, I.Zvara. Joint Institute for Muclear Research, Dubaa, USSR Some time ago at our Laboratory tbe chemical identification of element 104 (Ku) vaa carried out. It «as shown that, in contrast to elements with ZS103. Ku forms a relatively volatile anhydrous chloride, thus giving the answer to the question about the place of this element as the first transactinoid in the Periodic System. The chemical identification was simultaneously the first, as yet moBtly qualitative investigation of the Ku chemical properties. At present interest in the quantitative sbidy of the ohemioal properties of the elements of the second hundred in comparison with their homologuee from the Vita period increases in connection with the problem of relativistlc effects (RE)- All the previous investigations of Ku Indicated that It should be a d-element of the ZVth group. Xhose studies were not aimed at separating Ku from Hf. In order to discriminate between the properties of Ku and Hf we carried out the comparative study of the volatilities of Ku and Hf bromides and chlorides. 5 Experimentз were carried out using Ku (T.,/2-4.5 s; 7S6 s.f.) produced by the nuclear reaction 242^22 n"e,4n). The tnermochrooatographlc behavior of Ku compounds was compared with that of 1 5Ef (2, .„»75 е). She use of the Hf tracer whose lifetime is close to that of 2"&u allows one to minimize the necessary corrections to the experimental difference in the deposition temperatures of the two elements. Xhe inner surface of a quartz column served as a track detector for Ku fission fragments. As a result, the chemical syst- en was very simple. For the simultaneous production of "'Ku, 'Hf or other nuclides, composite targets were prepared, say, by depositing a REE oxide and thon a 4 Pu layer (1 mg/cm ) onto an aluminium foil. The experimental He ion beam with setup Is shown schematically in Fig. 1. lb» target was exposed t9o a 120 MeV an Intensity of up 22, to 2xl012 pps. The nuolear reaction products thermaliz- ed in the gas were transported by Wg. 1- Diagram of the experimental setup argon at fi flow 1-Cylinder with argon; 2-Ив<С104>2, 3-Рг05! 4-И. rate of 1 1/min. getter; 5-adjUBting valves; 6-bubbler with chemical A part of the argon reagent; 7-aerosol filter; 8-target; 9-heater of the flow was prellmlnar- gradient oven; 10-column; 11-aerosol filter; 12- ily saturated with activated carbon trap the vapours of Br2 and BBr,, or T1C1, and Socio respectively and fed Into the column. The partial ргеввиге of the agents la the mixci flow was about 1 mm Eg* She fused optical quarts oolusm with an inner diameter of 3.5 mm and a lenght of 120 cm had an isothermal section (10 om long) containing a quartz wool plug (0.5 cm) and a 110 cm thextaogradient zone in which the temperature 227 decreased emoothly down to the room one by, on the average. 3K par cm. Attar the termination of the experiment tf -spectrometric measurementв were carried out to determine the distribution of Hf leotopea along the column and the decontamination factor of the "Hf fraction" from the rare earth elements. The amount of the target material and other actinide elements present in the column was determined by measuring o< -aotivity in the wash-off from the column surface» After controlled etching with hydrofluoric acid the inner surface of the column waa scanned (through the wall) to reveal fission frag ment tracks. The pattern of the distribution of the tracks from 259Ku relative to the deposition zone is the same for both chloride and bromide systems, the only difference being that the zones of chlorides lie at temperatures about 100 К higher than bromides. Pig. 2 summarizes the data obtained in several two-day experiments performed to study Ku bromides in comparison with the profile of the Hf zone. It is seen that the Ku zone is considerably broader than that of Hf. It is even conceivable that we deal here with two closely neighbouring peaks which are unresolved because of insufficient statistios. The centre of mass of the "Ku zone is displaced towards the lower temperatures, compared with the zone. Only 50% of the tracks due to "9Ku decay are located within 90% of the area of the 1°5Hf zone. Ihe zone position depends also on the Isotopic hall-life, as Indicated by the data of Pig. 3. A factor of 5 decrease in 1^, leads to a shift by 10°C towards the higher temperatures in the case of broisidea under concrete conditions. Consequently the «one of the hypothetical Hf isotope whose half-life is equal to that of 259Ku can be expeoted to lie 6 cm to the left of the 1°'Hf zone. Hence it follows that even if Ku produced two peaks, the higher temperature peak is located below the main peak for Hf. The detailed picture is also characterized by the marked difference between the profiles of the Ku and Hf zones. A more comprehensive interpretation of the differences in the behavior of Ku and Hf will be possible after the performance of addi tional experiments and after comparing their results with those of quantum- mechanical calculations, as BE may manifest themselves in volatility, stability and/or formation kinetics of particular compounds. SOLUTION CHEMISTRY # •^iw'jse** RADIOCHEMISTRY AND ACTINIDE CHEMISTKYT£-|-| R. Guillaumont ' ' IPN -ttadiochemistry Laboratory, Orsay-France Within the framework of chemistry, true radiochcmistry deals with the behaviour of ultra diluted matter, that is to say with the chemistry of N species (atoms,molecules Jons) N being in the range of about 1013/cm3 (tracer scale chemistry ) to some units (atom chemistry) and dowr ''. N=1 (single atom chemistry). As isotopes of actinide elements -and isotopes of others 6p 7s and 6d radioelements too-сап be found in this quantities, radlochemistry and actinide chemistry (cis and trans actinide chemistry included) are closely linked. So: 1) experiments at very low concentration on these elements, particulary frr the multivalent ones, have to be performed with caution because the partition methods-the only ones which can be used -could possibly perturb greatly the true initial state of the system. 2)the behaviour of these elements have to be thought throughb unusual aspects of kinetic and thermodynamic of few entities, in comparison with classical chemistry, particulary when 1< JV^IOO. To discusss these two points wbe have first to define observable actinide chemical reactions and to classify them as "made man reaction" or "earth reactions" in terms of the species involved, their number, T, t, r, and Д( (T> t > т > At) w;th T half life of the radionuclide, t time reaction, т half life to reach stationnary or equilibrium state, At observation time. Ob servable actinide made man chemical reaction are those which are kineticlly allowed with t ~ г ~ At= 1 month for instance, while earth reactions are characterized by large t and small Д* values. Considering now the first point, it is an evidence that the partitions systems are chosen in such a way that the partition reactions are observable. The problem to be faced -and recently pointed out in actinide speciation -is to find a partition system which do not modify the initial oxidation states for multivalent actmidfs (Pa, U, Np, Pu). Going to the second point, for actinide chemistry at tracer scale (NsolO12 species/cm3) no problem arises and equilibrium of the species, whatever the observable reaction are, is upon the dependence of the law of mass action. Wben less than a hundred of species are involved in a observable chemical reaction some thermodynamical problems arise to describe the most proba ble state reached by these species. To find it the chemical statistic must be used in an unusual way. Important deviations from the situations predicted by the classical law of mass action could occur depending on the stoechime- try of the reactions. In the limiting situation when N=1 the stoechrometry for all the species including the atom is one to one and an equivalent form of the law of mass action can be found. Actinide chemistry as a function of concentration down to ultra trace dilution when suitable isotopes are awaible has to be deeply investigated in order to ide-..fey oxidation states and species. This could give valuable in formations about fundamental problems and as whe know about practicable problems dealing with the behaviour of actinides in the environment. 230 INVESTIGATIONS ON AQUEOUS CHEMISTRY 0? MESDELEVIUM AND OTHER 5-2 THANSPLUTOKIUM ELEMENTS G.V.Buklanov, B-Gorski, Ы Den Doc, A.Milott, L.I.Salamatin. Joint Institute for Huolear Research, Dubna, USSR Studies of the aqueous chemistry of the actinides in comparison vita that of the lanthanides are of fundamental importance for our understanding of the chemistry of the heaviest elements. Our investigations are aimed to study the chemistry of Hd and other transplutonium elements (TOE) in solutions, especially the extraction of tad(III) in the presence of complexing agents and also the oomplex formation of Hd(IIIl. Hendelevium-256 «as produced in a multinucleon transfer reaction by 9 2 bombarding a * Bk target (0.5 mg/cm Bk02 on a 8 pi thick beryllium foil backing) with 22Ne ions (120 HeV) on the external beam of the U-300 cyclo tron. The products from the heavy ion reaction were collected on quartz or glass wool. After the irradiation the collector was washed with small amounts of diluted HC1 or 0.07Mrf-HIB solution at pH=4.75 containing the lanthanide tracers " Tm, 1 Tb and also 88Y. The lissolved reaction pro ducts were transferred into a precalibratsd chromatographic column (Aninex A5i 55x2 mm). After the separation of lid from Fm by oC-HIB and the evapora tion of the solutions with HNO, the mendelevium can be used for investiga tions. The experiments for other IPE were carried out using '''Am, *4^Cm and *'0f. The measurements of Am and "Of were performed using a HaKTl) detector, of Cm by a Si(Au) semiconductor detector and "lid by a neutron detector for rare spontaneous fission events Л7- At first we studied the extraction of lid in comparison with other ТГЕ and REE with trioctylphosphlneori.de in the presence of DTPA and laotic acid. We used AKNO,),, Cu(HO,)2, HKNO^Jg as salting-out agents. The results are shown in Table 1. Table 1. Distribution Coefficients of IPE with 0.1И TOPO in Benzene from Solutions of 0.07 M DTPA» 1 U Lactic Acid Salting-out agent Kd salt С (mol/1) (mol/1) Tm Am Cm Cf Hd A1(H03)3 0.45 0.35 0.57 2.06 2.23 3.30 Ои(И03)2 0.48 0.30 0.20 0.86 1.30 1.92 1.7 Ni(S03)2 0.48 0.20 0.15 0.80 1.24 1.50 1.5 Furthermore we investigated the complex formation of Am, Cm, Cf and Hd with 1.2-diaaine cyelohexane tetraacetic acid. The stability of the complex es has been determined using ion exchange. In these systems one kind of complex compounds is formed and the stability constants J3L can be obtained from the distribution coefficients Kd (in the presence) and K. (in the absenoe) of a complexing agent 231 J»n- where £bj is the equilibrien concent:»tion of the coraplexing agent. The experiments «ere carried out at the constant ionic concentration if 0.1 (NaC104 or BH40104) at pH 2-5 and at 20°C. * The obtained stability constants are shown in Table 2* Table 2. Stability constants of TPB and REE Complexes with 1,2-Diamlne Cyelohexe Tetraacetic Acid Ion log 0 РшЗ+ 17.80*0.08 m>3+ 19.65*0.04 Tm3+ 20.69-0.04 уь3* 20.81*0.04 Am3* 18.70*0.04 Cm3* 18.78*0.04 Cf3+ 19.56*0.04 lld3+ 19.5 * 0.6 The results for Am, Cm and Of and for the BEE are la good agreement with the values obtained by other methode /§7. As known, the distribution coefficients in ion exchange systems reflect the ionic radii /37" and for ions of the same charge and coordination number Ig K* is a linear function of the ionic radii. Shus we have analysed the correlation of the ionic radii with the values of lgfi for the REE and TPE in the systems investigated. References 1. Ter-Akopian O.M. et aW/Ifuol.Instr. and Meth. 1981. Vol.190. P.119. 2. Goraki В., Li Ben Dok//Preprint JIMR PI2-88-166. Dubna, 1988. 3. Marcus Y., Kertea A.S.//Ion Exchange and Solvent Extraction of Metal complexes. М.У.: Wiley Intersoi., 1969. P.287. 232 SOME POSSIBILITIES OF STUDYING THE AQUEOUS CHEMISTRY OF KURCHATOYIUM AS A TRAHSACTINOID ELBHEHT 5-3 Z.Szeglowski, V.P.Domanov, B.Gleisberg, I. Z vara, Joint Institute lor Nuclear Research, Dubna, USSR H.druchertseifer. Central Institute of Isotope and Radiation Research, Leipzig, Gffi L.I.Guseva, G.S.Tikhomirova, Vernadsby Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Moseow.USSR H.Huesonnoig, Institute of Nuclear Physics, Orsay, France The first isolation and chemical identification of a short-lived isotope of kurchatovium «ere accomplished by the gas-chemistry method (\,2?. She results indicated similarity between Ku and the transition elements of the rvth group of the Periodic System. Later Z3.47 the analogy of element 104 with ZT and l£f in their cationic-exchange behaviour in concentrated HC1 and oc-hydroxylsobutyrlo acid solutions was shown. Very short half-lives and low production cross sections of the isotopes of kurchatovium make the ntudlea of its aqueous chemistry difficult. In the present paper some new possibilities were investigated of the separation and chemical identification of Ku producible at the U-400 cyclotron in the reactions of 4 Cm with 180 ions. The identification of 261 Ku can be based on the detection of o( partioles from the decay of its long-lived descendants (TPE nuclei) £-J. These particular nuclides are also produced directly in nuclear reactions, Therefore it ie necessary first to purify the Ku traction from TPE to a high degree. For this a rapid liquid chromatography method was used. Model experiments to separate Hf from TPE and REE were perfozmed. A continuous method is desoribed of the fast chemic al isolation of short-lived Hf isotopes direct from the target under bombardment by using an aerosol jet (Ar + NaCl) for transporting reaction products to the ion exchange columns selective to various elements in solu tions of eomplexing agents (Fig.). Scheme of separation apparatus: 1-argon cylinder, 2-aerosol generator, 3-heavy ion beam, 4-target, 5 —spiral tubing, 6-filter, 7—inlet of eluent, 8-absorber, 9-degasser, 10—peristaltic pump, 11-column with Dowei-50, 12-Sowex-1, 13-Dowex-50 233 16s The short-lived ~1°9gx aerg produced by the bombardment of natural Sm end Sm targets by Ne Ion beams. The distribution coefficients «ere determined for some TPB, BEE, Zr, and Hf on the ion exchangers: Dowex-50, Dowex-1t and neutral eorbent «ith HDBHP from CC-jOCOH, HjCgO,, НИО, + ТОЮ, БЧРО. end HP [ exchange columns in shorter time than is the half-life of Su (Т. *г>>65 в). Hf radionuclides (^70%) were sorbed by anion exchange column 12 contain ing Во«ех-1хв resin* Фае developed method completely simulates the condi tions of the chemical isolation of kurchatovium. The identification of 1Ku may be performed by measuring its ос-decay or tbeot-deoay of descendants, e.g. "ES (1./2=20 d),after the desorption of Ea from chromatographic column 13 by small quantities of HOI and BHO3 solutions. References 1. Zvara I., Ohuburkov Yu.T., Caletka R., Zvarova T.S., Shalaevsky II.R. and Shilov B.V.// Atomnaja Bnergiya 196C. Vol.21. P. 83. 2* Zvara I., Qtuburkov ia.T., Caletfca R. and Sbalaevsky U.S.// RadiokMmiya. 1969. Vol.11. Р.16Э. 3. Sllva R., Harris J., Hurmia II., Sskola E., Ohiorso A. // Inorg. Nucl. Ohem. Letters 1970. Vol.5. P.871. 4. Hulet E.K., Lougheed R.W., Wild J.P., Landrum J.H., Nitschke J.II., Ghiorso A. // J. Inorg. Nucl. Ohem. 1960. Vol.42. 1.79. 5. Oganeesian Xu.Ts.. Hussonnois H., Dentin A.G., Kharitonov Ju.P., Bruchartseifer H., Conetantinescu 0., Korotkin Yu.s. * Tretyakova S.P., Utyonkov V.2., Shlrokovsky J.v., Estevez J- // Radiochimica Acta. 1984. Vol.37. P.113. 6. Bruchertseifer H., Hussonnoia M., Constantinescu 0., Buklviov Q.V. UN, Orsay, rapport annuel. 1987. P-103- 234 AQUEOUS CHEMISTRY WITH ELBMBHT 105 i 1 W.Bruchle, H.Sobad«l. O&L Dannatadt, PHG 1 5"4 ] J.V.Krets, u.ff.Scherer, P.Zlomerinann. University Hftlns, SRG C.H.Gaxmett, K.B.Gregoricn, H.L.Hall, R.A.Henderson* D.C,Hoffman, D.M.Lee, y.J.Nurmia. LBL Berkeley» USA U.BeltenBperger, H.Gaggcler, D.Jost, Y.Hai-Qi. ESI ffurenllngen, CH G.Lienort, A.Turler. University Bern, CH 262 249 18 We produced 105 (TV2=35s) by irradiation of a llk target with 0 at the 88-inch cyclotron in Berkeley. Reaction products were transported by a He- KCI- jet to the sampling position of the Automated Rapid Chemistry Apparatus, ARCA. After 1 min of collection the products were dissolved and processed automatically. Micro separation columns, as small as 1.6mm x 8mm could be changed within a fraction of a second from two magazines, containing 20 columns each, A dead volume of about 35^1 for the whole apparatus minimized the used volumes of acids. The aqueous tractions were evaporated on Та disks by a focused infrared lamp and a hot helium beam to prepare them for a- and spontaneous fission- spectroscopy. Typical times between end of frradiation and start of measurement were between 45s and 65s. Nearly 2000 individual experiments were performed in a cyclic mode of operation. In a first series of experiments we were testing the hypothesis that element 105 should be extracted into tertiary amines, (Ike its homologs Nb and Та. We choose trHso-octyl-amine absorbed on taflon powder as extracting phase. We could show that element 105 is extracted from 12n HCM0.02n HF. and 10n HCI, like the homologs. In these experiments we. washed the columns with acetone -o strip the amine with all extracted activities. In the next series we choose 4n HCI/0.02n HF for backextractlon of a Nb- and Pa- (ractlon, and 6n HNOg/0.015n HF for а Та fraction. More than 90% of the a's assigned to the decay of 262105 were found in the Nb + Pa fraction. This result clearly shows that in the system we have chosen element 'OS behaves similar to Nb and Pa, but not to Та, which from a naive extrapolation may be somewhat surprising. In the last series of experiments we tried to differentiate between a Nb- and a Pa- like behaviour. The backextraction with 10л HCI/0.02Sn HF yielded a fraction containing 80% Pa and 20V» Nb. the snipped fraction with 6n HNOj/0.015n HF contained 20% Pa and 80% Nb. Element 105 was split to equar parts between both fractions. # 235 OXYGBH ккзвшж ш тнв зппяс о» летала, IOH SUCTIONS ингав EFFECTS (Ж ИвЯТ ABB J'-BADIATIOH | 5-5 | 8» A. Gaaiev, L. б. Hashirov, D. If. Suglobov. Khlopln Badium Institute, Leningrad, USSR In terms of chemistry the gist of radiation aotion on the matte? reduces to generation of particles with high reactivity (excited molecules end ions, electrons, atoms and radicals). Obese partisles are able to sti mulate deep changes in chemical composition of matter* Therefore, when studying such phenomena as photolysis and radiolyais first of all we must aolro the problems of composition and yield of initial active particles» laotoplc exchange is an affective method of their study. We have used oxy gen exchange reaotlon betoreen uranyl ion and water to investigate the pro cesses talcing place in uranyl aeneous solutions under action of eleetro- magnetle radiation. In acidified aqueous solutions uranyl ion does net practically exchange its oxygen atoms with water noleoules. Intrinsic exchange begins at pB>2, and It la explained by the hydrolysis of urenyl ion. In acidic solutions of uranyl perchlorate the rate of oxygen exchange reaction strongly Increases under action of visible .light radiation. We have found that this proeoBs is oaused by the appearance of uranoyl ions, uoj, as a result of oxidation of rater molecules by photosxeited uranyl lone. Hhese are UO^ ions that exchange their oxygen atoms with hydroxonlua ions. She sloetron exchange between U0| and Oo|+ is also Involved, Jberefbre, the quantum yield of oxygen exchange Ф can be above 1. By adding effeotlve oxidants of uranyl ions (3,o|~, Clg) we block the electron exchange and deoreaee Ф to •> 0,0в« whloh is essentially the quantum yield of uranoyl ion in the oxidation reaction of water molecule by photoexclted uranyl ion. On the contrsy at the presence of substances oxidised easier than water, Ф substantially Increases owing to the rise of yield and lifetime of uranoyl ion. Рог example, whentile solutio n is saturated with 30,, Ф~2.«Л High concentration of Vol in solution supposes the presence of significant amounts of counter-radical, sot, w)J.oh la known as an Inductor of oxida tion reactions by oxygen, the combined bubbling of SOg and 0g through irradiated uranyl solution leads to catalytic oxidation of S0£ in a chain reaotlon with quantum yield more than 10. The initial product of oxidation of water moleoulee by photoexcited uranyl is hyaroxyl-radioal Ш. Its interaction with different substances oan be studied in this system dlreetly using oxygen exchange as в detector. 3he raaotion of OH with carbon monoxide was Investigated by this method. 00 causes notioeable acceleration of photostinulated oxygen exchange with simultaneons appearanee of COg and I) (IV) with equal quantum yields. But the yield of П (IT) proved to be by an order of mag nitude higher than that axpeotad for dlsproportionatlon reaction, proceeding from the stationary concentration of OOj evaluated by the rate of oxygen exchange. Bus allowed to propose the following interaction mohaniaai CO + OH-»00L, + H. 236 Aotochemical efficiency of different electronic excitation levels of uranyl was estimated By the oxygen exchange method. When measuring Ф In 1 II HC10. solution In the presence of additions of other substances as a function of excited radiation weve length, we have found that in t-e case of easily oxidated molecules (such as CJHJOH, SO?") risible light at 350 < Д < 4B0 nm is equally effective and provides HO* quantum yield ~1. Por hardly oxidised particles (Н,0, <Я~) then is a distinct maximum near 440 nm. Ultraviolet radiation ( Л < 330 no) for both groups of subBtances is twice less effective* She data analysis allowed to propose the scheme of exalted ursnyl energy levels In aqueous solution and to grouni' the supposition that all components of the splitted lowest triplet state are photoehenieally effective. Their position determines the variation of мЩ* oxidation potential and population - the oxidation product yields. In the ease of photoexcitatlon the energy is brought into solution through the dissolved substance, for example, uranyl and at the radio- lysis - chiefly through the solvent. The main result of jf -radiation action is radical generation, therefore, the ability of uranyl to detect (through oxygen exchange) strong reductants (»*, H) can also be informative. We measured radiochemical yield of uranyl oxygen exchange in/-irradiated aqueous solutions (Co, dose rate ~ 250 rad/S). Similar regularities for radiochemical and photochemical oxygen exchange yields as a function of acidity, uranyl concentration and oxidant presence have been observed. However, the radiochemical yield 1в essentially higher than Ф (taking into account absorbed energy). In the ease of Jf -radlolysis for production of one Ш>2 ion no more than 3 eV are consumed. The water oxidation potential in acid solutions Is !i,b 7; therefore It comes out that In the initial acts of interaction between /-radiation and water the energy is not practically dissipated* to vibrational-translatlonal degrees of freedom. 237 HYDRATB-SOLVATB IKOPERTIES OP DIVALBJT LABTHASIDBS 5_g АШ) ACTIHIBBS • N.S.Hlkheev, A.H.Kamenakaya. a.A.Kulyukhin, I.A.Humer. Institute of Ehysioal Chemistry of the Academy of Sciences of the USSR, Moscow, OSSK The analogy between alkaline earth elements end divalent aotinidea and lanthanldes пае been qualitatively verified Ъу валу investigators. To obtain quantitative date confirming this analogy, we have determined the hydration energies of divalent lanthanides, which have been oompared with the respec tive values for the lone of alkaline earth elements 07- W-e dependence ot the hydration energies on the lonlo radius for the elements of both faniliee has proved to be described by one and the sane function* reflecting the Born equation* However, such a dependenoe Is-violated, when the mixture of two solvents - water and ethanol Is used /Я/. Doing the method of oocryatallizatlon of divalent lantbanldee and ein steinium (II) with SrSO^, It has been shown, that an increase In the water concentration leads to the eh&nge in the ratio of the solubility product of BuSO.. XhSO, and EsSO. to that of SrSO.. Over the water concentration range from 2 to б mol/1 for ytterbium this ratio decreases, for europium it in creases, and for einsteinium the minimum is achieved at HJO.OJI^OH.ISS,which conforms to the formation of the most strong eolvate-hydrate eouplex of di valent einsteinium BsSO^nHgOanCj^nyni, where n is most likely to be equal to 2. At the water concentration above 10 mol/1 for all the elements under study the ratio of the solubility produot of their sulphates to the solubility pro duct of strontium sulphate does not depend on water concentration, which points to the saturation of the coordination sphere of Ions with water mole cules. This conclusion has been verified by spectrcjhotomfttrlo studlee. Dhus, when the solvation shell '6"f divalent lanthanidee and aotlnides Is replaoed by the hydration one the levelling of these elements with respect to stron tium is observed. Referencee 1. Hlkheev Я.8., Burner I.A. // Radlokblmlya. 1987. Vol. 29, N 1. P. 112-113. 2. Vlkheov H.B., Kamenskeya A.K., Rulyukhln S.A. // Radlokhimiya. 1988. Vol. 30, И 2. P. 213-217. 238 SUPERACID ACTINIDE CHEMISTRY: REACTION CHEMISTRY OP SOME ACTIHIDE METALS, OXIDES, AND FLUORIDES L IN HF/SW'5 Larry R. Avens, Kent D. Abney, P. Gary Eller Scott A. Kinkead, and Larned B. Asprey, Los Alamos national Laboratory, Los Alamos, NH 87545 USA The superacid mixture HF/SbF5 is one of the most powerful protonic acids known. The actinide chemistry of this media is surprising in two regards: the solvent will support actinides in solution up to concentrations approaching one molar, and the solvent is extraordinarily effective for the dissolution of oxides. Ordinary actinide oxides (oxalate derived materials fired at approximately 600°C) dissolve completely in minutes in room temperature solutions of HF containing about 10% sbF5. High-fired actinide oxide materials take longer to dissolve, but usually give total dissolution in less than one day. The dissolution of oxides appears to be a general reaction: + M02 + HF/SbF5 .—> M(SbFg)x + 2 H30 SbFe Here uranium, neptunium, and plutonium retain the IV oxidation state while americium oxide dissolves to give solutions of Am III. The actinide metals dissolve with hydrogen release to give solu tions of the metal in its lowest stable oxidation state. Actinide tetrafluorides dissolve very slowly while the trifluorides dis solve in minutes. This effect is likely related to the lattice energy of the solid fluorides. The dissolution, reduction, and oxidation chemistry of some of the actinide elements in HF/SbF5 will be discussed. 239 игатоютгагасЕЯСЕ OF AMERICIUK (HI) IH AOUEOUS AHD ORGANIC SOLUTIONS 5_8 i A.B. Vueov. Institute of Physical Chemistry of the Aoademy of Sciences of the USSR, Bob'oow, USSR The speatra ar.d lifetime of pbotoluminescence (PL) of solutions of Am(III) were measured in H2O,Dg0, in organic protonized and deuterated solvents and also in solutions of thenoyltrifluoroacetone (ТТЛ), of fresh-prepared peratung- state anc of unsaturated heteropolytungstetes. Excitation of PL was done Ъу copper laser ( X »510.6 nm) and in case of oomplexating reagents-also by nit ric laser ( X -337.1 nm). In all cases spectra of Am(III) PL consist of three intenee groups of li 5 5 nes in the regions 690-740 nm (D., —"'P,) 820-860 nm ( D7—-^Pg), end 1020- 5 7 5 7 1050 nm ( D1—» P,). As a rule, transition D1 —" P0 (about 570-580 nm) вав not been almost observed. The most intense transitions is ^D.. —*'P-; intensi 5 ties of transitions D^ —•> 'Pj and 'D1 —•• 'P- for Anrtaq are equal approxima tely to 0.8 and 0.7 respectively from the intensity of transition D1—»^P., in other media long-wave PL ie even weaker.The measurements of the lifetime of PL showed that to obtain bright PL of Am'+.solv the best solvent is dlme- thylsulphoxlde (DICSO). In protonlzed OHSO the lifetime of Am (III) luminescen ce is longer about 40times as comoared with that in H^O and in deuterated-more than 100 times and it equals to 2.7 mka, This phenomenon can be explained from the point of view of the luminescence quenching by highly frequent vib rations. In the presence of Uganda (TTA in alcohols, DMsOj paratungstate in wa ter), in the spectrum of Am(III) PL strong splitting of picks for components is observed. The brightness of PL increases considerably, obviously, due to тт removing of aqua molecules from the first coordination sphere of Ат( т) BIla it causes the deoreaee of quenching. The shift of maximum of absorption to wards the line of copper laser irradiation increases the brightness of PL as well. In the complexes with anions PV^O» and SiW.<10.q the luminee- eence of Am(III) at 29ЭК is observed only at ratio Asuligand* 1:1. In comp lexes with the ratio Amiligand- 1:2 complete quenching of PL proceeds pro 9 bably due to charge transfer between Am (III) and W(VI). In AmW.00,6 "euob quenohing is also considerable and the lifetime of luminescence Amw100-£ " in DgO at 293K is equal to 250-600 ne (decay of PL is not exponential); in the same time at freesing of the same solution down to 77K the lumines cence lifetime of Am(III) increases up to 1.5-3 mks, The data obtained tes 9 tify to more considerable PL quenching of 4mW100,6 " in comparison with Cm,10°36 and Tb*10°36 by tne cn,r8e transfer. And it is quite normal, taking into account greater stability of Am(IV) in comparison with Cm(iv) and Tb(IV). ? It baa been discovered that PL of the complexes Am(TM)n and AmW100,, ~ can be axolted by nitric laser ( Л "337.1 nm). I.e. in these complexes effective energy transfer from ligand to Am(III) takes place. The PL speotra la similar during excitation by nltrlo and copper laser. Thus, we have observed for the first time sensitised PL of Am (III) with excitati on in ultra violet region. The possibility of the effective energy trans fer is the ameriolum (XII) complexes permits to increase a number of light sources suitable for exoitstlon of Am(III) PL in solutions. 240 CURIUM AND AMERIOIUMCBEMILUMISSSOENCE IH REDOX REACTIONS T~ A.B. YUBOV, A.M. Fedoseev. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR New results are given in the field of chemilumlneBcen.ee (CD of actinides. It has been reported earlier about curium CL in the reaotions of its reduc 8 12 10 tion from complexes CmW^Ojg ", Cm(SiW110j9)2 ~ and CmXPW^Ojj^ ". The most intensive lumineecenoe has been obtained during the deoBy prooess of the initial complexes by alkalines with further reduction of curium (IV) to curium (III) by water. The redaction of curium (IV) by hydrazine, EDTA, DTPA without preliminary decay of initial complexes has given leSB bright CL. La ter curium CL has been discovered during dissolution of curium (IV) bioxide with lithium in mineral acids; in this process the formation of curium (III) took place elso. In this case CL was not intensive,Its yield was not higher than 10 -10 7 quants for an act of a reaction. During these researches we tried to discover CL of americiuu in the reac tions of its reduction from high valent states to Am(III). Am(IV) was obtai 8 18 10 ned in complexes AmW^C.g ", Am(Si»11039)a" or And^O^j ". Am(VI) was prepared by oxidation of aqua solution AmtelO.)., by sodium persulphate. Weak CL WBB discovered during reduction of Am(IV) from complexes Am»100,j ~ (pH 3: 6) and Am(VI) in alkaline medium. In both cases hydrazine and its deri vatives (pickoline-hydrozine, nikotin-hydroslns) or complexons (EDTA,DTPA) represented reducers. In all reactions the last form of amerieium was Am(III). The use of other reducers OnuOH, Na2S0~, NaHO-, H«0, ascorbic acid, pyro- hallol, Na2S203> H2C204, HCOOHa, Sn(II), Hn(II), V(II), V(III), Pe(H), U(III), U(IV) under the above mentioned conditions does not bring to CL as well as reduction of AmC'I) in aoid medium by none of the reducers used.In difference from Cm(IV) decatungstats, americlum (IV) decatungatate has not given CL during its decay by №0H, KF or Th(C10.)., Probably in these reactions the reduction of Am(XV) or the decay of complexes proceeded too slowly, but all discovered CL reactions ended for the time 2-3s and no longer; the tijne of CL irradiation was the same. The CL yield in the discovered reactions —о «11 lies in the range 10 '-10 quants for an act of reaction. Hot high yield of CL is partially connected with low yield of photoluminescence (PL) of Am(III) in aqua solutions (about 10~5). Spectral region of CL in the most bright reactions has been determined using monocbromator. In other cases using glass filters with one-side border of transmission. The results obtained have been compared with PL spectre of Am(III) in which, as a rule, three groups of line are observed, the most intense in the region 690-740 nm -,7 5 7 (transition ^j"" P1) and less intense - at 830-870 nm ( D1-» F2) and 7 1020-1050 nm ('D1-*- P,). It turned out that CL was observed in spectral region ^ 650nm. The exact determination of CL spectral region was rather difficult because of small brightness of CL. nevertheless tbe data obtained testify that spectral distribution of CL for the reactions of AmW^O-g8" es sentially differences from that for the reactions of Am(VI). In the first case the CL concentrated mainly in the two regions of 680-760 nm and of 800-880 пш, while in the second case CL emitted in one spectral region of 650-950 nm with tbe maximum near 750-850 nm. ThuB, the CL spectrum in tbe I6.3ax.I607 241 JSmW 0 10 36 reactions ia In a good accordance with tbe РЬ spectrum of AmW10o_g'~ and the emitter here is apparently Am(III). And in the reactions of Am(VI) the emission evidently belong to tbe products of tbe reduoers oxidation • that confirmed by tba presence of 3L with tbe same spectral characteristics in the reactions of oxidation of 8 So ire have to do with true americium CL only in the reaction of Am*100,g ~ reduction. There are two indirect evidences to tble conclusion. First,t^e 8— в. emitters in analogous reactions of Cm>100.^ and ТЫ»100,6 bae been deter mined reliable - it ia an ion of trivalent f-element; emission in the region 2- > 650 no in thes10e reactions Is absent. Second, in reactions of toUSlW^O,-Л and Am(PW11o3„)j " with HgH. we ware not able to fix reliable any CL, although the Am(IXI) formation proceeds aa quickly as in tbe АвМ^о^Зб reac tions. It is in agreement with th» PL absence of AmCsiW^O,-),13" and AmtPW^Oj.Jj11" because of full PL quenching by charge transfer between Ат*<Ш) and W(VX). But during tbe reduction of these complexes by DTPA the weak CL arise (ite yield leas than 10" quants for an act of a reaction). Its nature has not been ascertained, but probably it belongs to AmCXXl}, so far aa a part of initial complexes may be deatructed by DBPA before Am(IV) reduction oc curs d. So tbe CL in this reaction шву emitted by Am(XXI) that turned into the complex with DTPA. Thus, tbe data obtained testify to tbe CL presence of Am in reduction reac tions of AmW1Q0-g and possibly, in reduction reactions of Am(VI) in alkaline media. It must be noted tbat americium CL has been observed only using strong reducers. It is an important difference of curium CL, tbat has been the most bright in reduction reactions of curium (IV) by water. 242 PHOTOCHEMICAL DECOMPOSZTICW OP QIA1AIS IOBB BY UBANYL ION'S Si 5_,0 NITRIC ACID SOLUTIOH ' S. V, Krupitskii, B. Ye. Oalkin, V. H. itomenovekii. Khlopia Kadium Institute, Leningrad, USSR Photolysis of uranyl ions in oxalic aeid solutions has been the subject of several works. №з raeults of investigations have shown the possibility of its practical use in actinometry and analytical chemistry* ЯЬб photoly sis mechanism is proposed which takes into account electron transfer from oxalate ions to excited uranyl. The formed oxalate radioal, in turn, can Interact vith uranyl ions and the dieproportionation of pentavalent uranium leads to accumulation of tetravalent uranium in photolyte. She study of photochemical decomposition of oxalate ions by uranyl was conducted in solutions containing different anions: sulphates, phoephates, halogenides; their influence on the prooees «as ascertained. The data on photolysis of uranyl ion in nitric acid solutions containing oxalate ions are scanty. 5be present communication is devoted to the photochemical decomposition of oxalate lone by uranyl ions in nitari.0 acid solutions, Experimental part. Ob» irradiation of nitric acid solutions of uranyl nitrate containing oxalic acid was carried out under static conditions with the light of PHK-7 mercury-quartz lamp at 20 + 2°c. The results on oxalic acid decomposition during photolysis without forced agitation of 1 К Ш0, solution with variable content of uranyl ionB пате shown that the decomposition of oxalate ions at uranyl ion concentration below 5.10"3 M obeys the exponential equation: #x£ . iUtf^e-W, where fyJQ - the Initial concentration of oxalate ions, /OxjJ - the con centration of oxalate ions during photolysis r, x - rate constant, time-1. With increasing concentration of uranyl ions above 5.10"^ u the decompo sition of oxalate ions slows down and doea not proceed to completion. The oontrol tests on phoiodecomposition of oxalic acid in sulphuric acid solutions revealed that the photolysis process follows the exponential relation at higher concentrations of uranyl. We suggest that a distinction between the processes taking place in sulphuric and nitric acid madia is caused by side photochemical reaction resulting in accumulation of nitrite ions according to the equation: HOj —- NOg + О We have found that the yield of nitrite ions increases with increase in oontent of uranyl ions and nitric acid. Ibis increase cornea about, in 243 our opinion, at the expense at uraayl-ion excitation energy transfer according to the equation: B*o|+ + NOj £*tto|+ + 11*03 . Further investigations were performed with bubbling agitation of solutions using inert gas or air for elimination of nitrite ions. It should be noted that the agitation of sulphuric acid photolytee with argon bubbling has no influence on photodecompoBition of oxalic acid. Ihe results obtained have indicated that the use of agitation with inert gas bubbling during photolysis enables to avoid the deceleration of oxalate-ion decomposition in nitric acid solutions, and the process proceeds scoording to the exponential relationship. Hie values of rate constanta for the photodeeomposition process of oxalic acid at different concentrations of nitric acid are given in the Table. Bate Constants of HgOjO, Photodecomposition for Solutions with Uranyl-Ion Concentration 2.1.10 M HBO,, 11 0.5 1.0 2.0 3.0 k.10'2, min"1 11.5+.1.1 5.71+0.14 2.81+0.08 1.95+0.08 It is evident from these data that the process rate decreases directly with increasing nitric acid content. In contrast to sulphuric acid photo- lytes, tetravalent uranium was not detected in these tests with the exception of the solutions containing the concentrations below 0,2 a HN0,. The absence of uranium (IT) is associated with its oxidation by HN0,, because dissolved oxygen is removed from solutions by inert gae before the photolysis. £0, it is of interest to study the influence of oxygen (air) introduced into reacting mixture on photodecompositioa of oxalic acid. She results on photodecompoeition of oxalate ions by uranyl ions under conditions of agitation of photolytee with air bubbling point to the increase in the process rate. Therefore, the photolysis with air (oxygen) bubbling not only eliminates the accumulation of nitrite ions, but also gives rise to the side reaction involving the oxidation of pentavalent uranium: + UO* + 02 . D»o| + 0g . 244 OOMPLEXATEOW О*' ТНГ- AND TETHAVALENT ЛЛ1ЕК1С11Щ AND BERKELIUM WITH Н2Ю~ TONS ш ACETONITRILIC SOLUTIONS . Г7"—l I 5"11 I S.A.Perevalov, I.A.Lebedev. Vernadeky Instutute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR The complex formation of Am5+ end Bk^+ with HgPOT ions in ecetonitrile has bfipn studied spectrophotometricelly PL^PJ from meesurjyment of optical density of nrnpriciumCin) Rnd berkelium(III) solutions fit verious concentrations of phosphoric acid (in the range 5 x 10"* - 4.0 M_) and at г constant concentra tion of the trsns-plutonium elements (TPUs) (|Лш(111)3 = <1.3 x IO"5 К and [31c(IIl)J = 9.S x 10 К ). The composition of phosphate complexes of Am(III) and Bk(III) has been defined from the dependence of average molar extinction coefficients upon concentration of В^РОГ ions. From the fact that Am* and 7 4 (3-i> r Бк1,5** font complexes of the general type K(CHjCS)n_i(H2POi()i -'~'-'' with SyPO^ Lons, the stability oonstnnts (Bj) °^ the complexes have been calculated by the following equetioo: &, £Q* a?isi 1У°Д I + ft^Lvs]' I i 15 + where i=I,2,3,..., 80 = molar extinction coefficient of the solvated ions Am Bk*+ ; 6; з molar extinction coefficient of the complexed ions Аш-+ end Bk*+. The values of S- and ft ^ have been calculated as per the SIMPLEX method ge nerating averHge 6 values, following which it he.s been shown that the de pendence of С upon log QyPO^l is better represented for complexes with one and. two ligands. The complex formation t .* Am and Bk with'HgPO^ ions has been investi gated by potentiometric method from measurement of formal redox potentials of the couples Am(IV)/Am(III) and Bk(IV)/Bk(III) (in the range of concentration of K,POa 0.5 - 4-0 M) in acetonitrilic solutions. Increase in the concentra- les Am(IV)/Am(III) and Bk(IV)/Bk(III) which show greater complexation of Am(IV) end Bk(IV) than that of Am(III) and Bk(lII), respectively. Stability constants of the complexes of Am(IV) and Bk(IV) with H^PO^ ions have been computed from Nernsb equation. Comparison of the stability constants of the phosphate complexes of americiura and berkelium is presented in Table I. Table £. Stability constants of phosphate complexes of americium and ber kelium in acetonitrilic solutions 2 Composition of the complexesi MCH-JPO,,) * M(H2PO45| М<Н2РО^)+ Element 'l h h Am 1.3 x I012 2.1 x IO2* 2.5 x IO*6 Bk 1.4 X IO12 2.0 x IO2* 2.6 x 10** Thermodynamic parameters (UG , iH , AS° presented in Tpble 2) for complex 245 formation reactions of Am(III) and Am(IV) have Ъееп computed frou. the stabi lity constant vjiiues of phosphate complexes of №erioiurj(Ill) and <-n:erici- um(IV) as a function of temperature. Table 2. Thermodynamic parameters for complex formation reactions of .'.;r.>f and Am with H-PO^ ions in acetonitrilic solutions (T - 29S K) 1 1 1 1 Complexes A0°, kJ-mol" AH°, kj.inol" 4S°, ,1.К" ЧПО1" 2+ I. Am(H2P04) -70 t 4 9± з 26* i н 2. Am(E2I>04)* -139 i 2 30 i 2 566 i 5 3. Am(II2PO^)* -262 i И -2J4 i I* IGI i w Analyses of the data in Table 2 show that phosphate complexes of Am(IIi) and Am(rv) are of inner-sphere type which has been attributed mainly to the large poeitive change in entropy for the complex formation process. References £. Perevalov S.A., iebedev I.A., Myasoedov B.F.//Jtediokhiniiya- I9S7. T.29. S.593- 2. Perevalov S.A., Lebedev I.A., Kulyako 7u.M.T Myasoedov B.i.// Radiokhlmiya. 1988. T.30. S.452. f # 246 POTEHTIOMETRIC STUDIES ON ТНБ AQUEOUS PEUORIDB COMPLEXES OP Г _12 ACTIHIDES I—Z S.K.Patil, N.K.Chaudhuri, R.H.Sawant. Fuel Chemistry Division Bhabha Atomic Research Centre Trombay, Bombay 40008b» India Studies on fluoride complexing of actinide ions is of much interest in the solution chemistry of actinides not only because of its role in the separational and analytical methods but also due to the basic understanding of the predominantly electrostatic interaction in the formation of the ionic complexes. A critical review by Bond and Hefter[l] sponsored by 1UPAC was devoted exclusively to the stability constants of fluoride complexes in aqueous solution. The review emphasised fluoride ion selective electrode (P-ISE) as the best tool for studying the fluoride complexes in general and actinide ions in particular because of its high sensitivity» selectivity» sturdiness as well as non-interference with the oxidation states. A programme to study fluoride complexes of actinides was initiated, using F-JSE. It is usually necessary to use high acidity medium to prevent hydrolysis» polymerisation» disproportionation or change of oxidation state of the actinide ion of interest. This necessitates due consideration for liquid junction potential (E-) which varies with the acidity of the medium which in turn varies due to combination of part of the P" added with H+ to form HF. After each addition of fluoride if [H+] is measuredr the necessary correction for B- can be made. For obvious reasons the glass electrode can not be used to measure (H+J The only alternative viz. quinhydrone electrode also cannot be used as it either reduces [Pu(VI), Pu(IV) and Np(VI)l or oxidises (U(IV)l the actinide ions. The problem was overcome by developing an iterative computational method to calculate [H+J and thence E^ from the measured P-ISE potentials and used successfully to study fluoride complexes of hexavalent actinides[2]. Following the name procedure the data on some tetravalent and trivalent actinides have been obtained and presented here. U(IV),Pu(iv) and Pud ill perchlorate solutions were prepared by electrolytic reduction. Pu(in) was prepared also by reduction with quinhydrone. Experimental procedure was the same as reported in the earlier communication12]. Stability constants were calculated by nonlinear least square fitting to Bjerrum's equation. The results are presented in Table-1 and are compared with those from literature obtained under comparable conditions by potentiometric method. Overall concentration stability constants measured for Th(lV) in 1M perchlorate medium but with varying acidity were found to remain almost constant and the average values are given in Table-1. In the studies reported by Baumann on Th(iv) in 0.01K ionic strengthr E* values were neglected. In the present work» the data were obtained under the same condition and the JBJ values calculated by making due correction for E^. Present values are about an order of magnitude higher than those reported by Baumann and the difference may be 247 Stability- constant values of the fluoride complexes of actinides (Ionic strength = 1M) r • MetalIon lo^ log82 logp3 losPe Reference Th(IV) 7.63 13.3 17.26 23.40 This work 7.53 13.2 17.59 ь 7.46 4 udvi 8.50 14.72 19.59 23.75 This work 7.77 — 4 Pu(IV) 7.59 14.80 20.12 26.06 This work Put III) 3.15 7.42 12.30 This work Th(IV)* 8.91 16.28 19.88 27.58 This work 8.08 14.42 18.99 22.26 3 * 0.01 M Ionic strength attributed to Ej actinides follow the trend Th(IV) < u(iv) > Pu(IV). The preliminary values obtained for Pu Referenoes 1. A. H. Bond and G. T. Befter.// critical Survey of Stability Constanta and Related Thermodynamic Data on fluoride Complexes in Aqueous Solutionsr Pergamon, Oxford, 1980. 2. ft. M. Sawantr G. И. Rizvi, N. K. chaudhuri and S. K. Patil// J. Radional. and Hucl. chem. 1985. Vol.91 P.41 3. В. И. Baumann.// J.Inorg. Hucl. chem. 1970. Vol.32. P.3823 4. 6. R. Choppin and P. J. Unrein,// Transplutonium Elements (W. Miller and R. Lindner,Eds.) North - Holland, Amsterdam, 1976,P.97. 5. p. Klotz, A. Mukherji, S. Peldberg and L. Newman, Inorg. Chem. 1971 Vol.10 P.740. FORMATION OF THIOCYAKATE COMPLEXES OF TERVAJ5NT AMERICIUM, 5-13 CALIFORNIUM AND 1ANTHANIDES M.Borkowsbi, L.Baranlak*, S.Siekierski. Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw, Poland Our previous studips have shown that for soft ligands distribution ratios of actinide(III) ions are considerably greater than those of lanthanide ions of the same electron configuration. The difference between actinides and their if electron analogues may originate either in the aqueous or in the organic term. These terms account for complex formation in the aqueous and organic phase, respectively. In order to evaluate the contribution from each term, distribution ratios of Am and Cf between a xylene solution of tetraalkylammonium thiocyanate and an aqueous solution ol NH.NCS were deter mined and compared with those of lanthanides. If activity coefficients are neglected than the following expression for the distribution ratio is obtained: J D J^-4 t (Vn[»x];- , CD where x~ stands far the NCS~ ion, QX denotes the monomer of the tetraalkyl- ammoniun salt, •> is the complex formation constant and К is the exchange constant. In principle, all the constants can be determined by data fitting. However, it turned out that values of the ft constants critically depend on the region of low NCS" concentrations, which is not accessible experimental ly. Therefore, a semiquantitative approach was used. At constant concen tration af extractant the D/[)("]__ ratio is given by aq 7ЧТ- [x"Jfaq„ ' N i*E|3n[x where D stands for the constant organic phase term. From D/[X~]a o vs. DOaQ plot the average coordination number with respect to NCS~ ions can be deter х i + x erm mined. Thus, a constant value Df the [ "]а(У( ^-!^n^ ~^sa^ * '"Bans that the average coordination number, n, is 1. The comparison of the uV[X~]a_ vs- Сх~]„ plots for Am(III), Cf(III) and various lanthanides has shown that aqл n is decreasing with increasing lanthanide atomic number, and that with rest -ct to n the two actinides studied resemble light lanthanides and not their 4f electron analogues. * ZfK Rossendorf, GDR HMR STUDIES OP UHAHYb BBHZEHESULPHONATB 50LVATI0H AMD PRASE) 5-14~~l DIAGRAM OP URANYL BEN2ENESULPHONATB-WATER-TRIBUTYLPHOSPHATE SJ3TEU B.O,Aahevekaya, Leningrad State University, Chemical Department, L.L.Scherbakova, V^A.Scherbakov» Khlopln Radium Institute, Leningrad, USSR Results are presented on NMR Investigation, of the 'iranylbenze— nesulphonate (BSU) - water - tri-n.-butylphosphate С1ВР) ay a tern; the data have been obtained on the composition of uranjl aqua- acido-solvate сошр1ехев formed on the extraction of BSU with TBP. HUH - measurements were carried out with a PS* - 23-05 spectro meter (FUR spectra and their temperature dependences in the range of 300 - 170 K), and with a HUTISPBC PC 120 (proton relaxation). For Gibbs diagram of BSU - water - TBP system £"\ 1 additional data were obtained by a simplified technique of HMR-introscopy that proves to be more efficient than conventional chemical analysis* Xhe main feature of the PMR-spectra of aqua-aoetone BSU solutions are the relatively high temperature of signal separa tion for "free" and coordinated water molecules; this temperature increases with the increase of the TBP concentration* Юзе rise of the separation temperature is indicative of a longer life time of the coordinated water In uranyl aqua-benzene sulpho'nate in com- parision with mixed complexes with simpler acido-ligands C%J* there are at least three lines In the spectra of coordinated water. Aqua-complexes with non-equivalent water molecules со-exiet In solutions of small water contents, where P (molar ratio water : BSU) is less than 15* The mean hydration number, h . increases from 2 to A as P grows up to 15« Xhe presence Of disolvate preserved upon dilution with benzene, hexane or acetone was confirmed within non-aqueous solutions of BSU in TBP at L (molar ratio TBP : BSU) from 2.2 to H. Investiga tion of mixed aqueous-organic solutions at different P and L allowed to draw a conclusion that the extгасtable brutto-form of uranyl species In the system in question is the aqua-eolvate : [pO^CgHijSO^g. (H20)1^. (*BP)lejJ, Fractional solvation numbers for this complex and the results for the regions P=2.5 - 11 and Ьш2 - 4 strongly support the statement that in these solutions BSU exists as coordinated polymers with non-equivalent fragments 250 Evolution of the relative shift between benzene ring proton groups 1-5 and 2-4 is observed in PMR spectra of the anion; the eignal position depends on the nature of cations, dissociation, dentation and the number of coordinated water molecules* The above «volution ref lects charge redistribution of SO.,- fragments of the anions, whose con formations as a whole must lead to a reduced relative shift of pro ton groups. A change of the anion geometry, e.g. the- formation of inner hydrogen bonds and the with drawal of the benzene ring from the uranyl equatorial plane is li kely to occur through the tetra- aquaacidocomplex at P»15, where Phase diagram of BSU - wa Flffi spectra of the anion rtiff«*s ter - TBP system. significantly from the spectra in I - distribution region less aqueous complexes and consists II - solubility region of two broadened overlapped lines with a small relative shifts (0.40 p.p.m.; 0.80 p.p.m. for P = 4). The results obtained from PWR spectra of mixed solutions have been used to construct the phase diagram of the three-component system BSU - water - TBP in the P - 1 scale (Fig« ), where region III is of especial interest. Temperature dependence of the p - L diagram in this region has been investigated by KKR-introecopy of the phases from corresponding solutions. Addition of hexane into these solutions ie found to result in the formation of a second organic phase. Temperature dependence of the constitution of the second organic phase formed at diffe rent P and L has been analysed. All the above together with the NMR spectrum shape analysis and proton relaxation in solutions containing the solvent deuteroanalogues allow to consider regi on III of the P - L diagram to be related to macroscopically or dered solutions, i.e. to the state preceding a transition into the raetaphsse CiJ* References 1. Baluev A-V, et al.//Radiokhlraiya. 1988. T.30- S.349- 2. Seherbakov V.A., Scherbakova L.W/Ibid. 1976. T.18. S.203. 3. Senerbakov V.A., Scnerbakova L.L.//Ibid. 1984, T.26. S.708. 251 COMPLEXES OP ACTINIDBS AHD LAHTHANIDBS IN LOWER OXIDATION STATESl WITH СODIUM TETRAPHENYLBORATE I I N.B.Hikheev, S.A.Kulyukhin, I.A.Rumer, A.N.Kamensksya. Institute of Physical Chemistry of the Academy of Sciences of the USSH, Moscow, USSR Our discovery of a considerable stabilisation effect of aqueous Yb and Sm solutions in the presence of tetraphenylborate ion fSJ encoura ged the study of the process of the complex formation of divalent acti- nides and lanthanides with this ion, which is known to Ъе one of the weakest complex forming agents. To this end we used the method of cocrys- tallization of Yb , Eu2+ and Es with the solid Sr(SnOSO. solution from aqueous ethenolic solutions /27. In the presence of HaBFh. divalent lanthanides and aotinides in con trast to strontium have been shown to form cationic and neutral complexes. Their complex: formation constants J>1 and E>2 are equal to 6.5 and 25.7 for ytterbium(II), 1.7 and 52.7 for europium(II) and 6.2 and 106.4 for einateinium(Il). Using the spectrophotometry method it has been established, that the complexes have the composition JM(H20)J]fePhTl1and belong to the second sphere complexes. Since trivalent lanthanides do not form complexes with the BHj. ion, an assumption has been made that divalent lanthanides and actinidee form complexes due to the charge transfer from the hydrated metal ion to the phenyl groups of the BPhT ion £}f* She analogous pheno menon, obviously, takes place in the case of trivalent uranium, whose stabilization in aqueous solutions In the presence of KaBPh.^ has been also observed. If in water the half-oxidation period of uranium(IIIJ is about 150 h, then in the presence of НаВРЬд It increases up to 1400 h. since the complex formation constants of divalent lanthanides and actinides with the*BPh~ ion are low it is quite possible, that the strong stabilisation effect of the BPhT ion on the stability of aqueous solu tions of divalent lanthanides and actinidea, and U(III)is due to the "umbrella" effect. References Kamenskaya A.N., Mikhaev N.B., Kulyukhln S.A« et al.//Zhum. Meorg.Khlm. 1985. T.30» N 3. S.615-619- lfcLkheev K.B., KUlyukhln S.A., Rumer Г.А., Kamenskaya A.N.// Radiokhimlya. 1988. T.30, N 2. S.218-222. Mikheev N.B., Kulyukhln S.A., Kamenskaya A.N.//Ibid. НЭ. S.416- 418. 2S2 BEHAVIOUR OP MOLYBDATES OP 50ИЕ BLBIBHTS IM SODIUM HYDROXIDE I , , AND NITRIC ACID SOLUTIOBS 1 A.D.Prokoahin, E.A.Matyushin, O.A.Ustinov. All-Union Research Institute of Inorganic Materials, Moscow, USSR In nuclear power, metallurgy and radioehemietry compositions are widely used that contain molybdenum and its compounds with uranium, plutonium and associate elements (uranium are» metallic molybdenum alloys, a nuclear fis sion product - molybdenum fragment in a fuel matrix» molybdenum clads and heating elements that contacted uranium, plutonium and other compounds)* As a result of various chemical transformations all the indicated compositions form molybdates and complex molybdate systems that can be used to transform and separate uranium, plutonium and associate elements» The information on the interaction of uranium and plutonium molybdates with sodium hydroxide and acid solutions is not available* The data on the solubility of other molybdates are limited* This paper discusses the results of the studies dealt with the interact ions between uranyl, uranium (TV), plutonium (IV), ferrum (III), chromium» aluminium, nickel, calcium molybdates and sodium hydroxide and nitric acid solutions. Molybdates of the above elements were synthesized by sintering stoichio metric mixtures of respective oxides with molybdenum trioxide at a tempera ture of 70Q±2Q°C for 10-12 h* The completeness of initial oxide transformat ions into corresponding molybdates is controlled with an X-ray phase-shift analysis by talcing x-ray powder patterns In a camera of the РКУ -66 type using Co- and Cr-radiations. The synthesizing operations were conducted in air, for the exception of uranium (IV) molybdate. Uranium (IV) molybdate was synthesized in an argon atmosphere. In sodium hydroxide solutions beginning with the concentration of 0*125 mole/1 aluminium molybdate is fully dissolved, uranyl and ferrum iao- lybdstes decompose with molybdenum going into a solution and metal hydroxi des precipitating. Plutonium (IV) molybdate fully decomposes under the act ion of a NaOH solution at the concentration of 4 mole/1 for 2.5 h at 20°C. Molybdates of uranium (IV), chromium and nickel decompose by boiling NaOH solutions at different concentrations* The indicated molybdates decompose with the precipitation of respective metal hydroxides. Calcium molybdate is stable in sodium hydroxide solutions. 13% calcium molybdate decomposes on boiling in a sodium hydroxide solution at 4 mole/1 for 12 hours. The uranium and plutonium contents in alkaline solutions are not more than 2*5 and 1*0 mg/1, respectively* Nitric acid solutions decompose molybdates with H-HoO, precipitation. Uranyl molybdate decomposes by nitric acid at €-12 mole/1 and 20°C. Nitric acid solutions at 2-12 mole/1 decompose aluminium molybdate to 70-73*- Mo lybdates of uranium (IV), plutonium (IV)» ferrum (III)» calcium, nickel, chromium are decomposed by boiling nitric acid solutions of different con centrations* In these processes molybdenum loses with nitric acid are from 0.5 to 3-9 8/1. 253 Ш-SPbCThOSCOFX DEIiSMIMAlIUH OP BTABILITX COHSIANI OF THE COIitliX 5-17 M.A.Afonin, E.V.Komsxov, A.V.Smirnov. lensoviet Leningrad Technological Institute, Leningrad, USSH Forming of extractable complex U02 (N0,)2 IBP- was shown by osmometry /i/ (TBF is three-*i-butylphosphate) • The question about the character of coordin ation and stability constant of the D02 (HO,)2 TBPj is uncleaned yet. We have made attempt to determine forming constant of the J molecule TBP to U02 (MOj)g IBP2 complex in the carbon tetrachloride (CDC) by the analysis of IR-spectra. Spectra are shown in Fig.1, vibration bands are interpre- tated according Z?>5«£7- 119* «a-1 is band of =P=O...U in IBP coordin ated with uranylnitrate C*,b/, 1270-1285 cm"'1 is band of =P=0 in free TBP /2j, 1529 cm"'' is band coordinated nitrate-ion /"&/• Mono- and bidentate nit rate-ions axe supposed /Ц7 to have the same symmetry C2V, that is why we can пм DO^NO,), А я lbp=o и O=F£R (TOO * Ф 0 -а—оцц, St « йй «0 40 900 KM 4}00 (500 Ffwjuency.cm-' Fig.1 Fig .2 spectra of 0.1 ll TBP in CTC The structures of complexes of uran- ylnitrate with TBP. a) bid«=ntat:- nit assume the -M=0 (1529 cm.- ^) bond rate-ions; b) mono- and bidentate extinction coefficient not to de nitrate-ions. The oxygen atoms of pend on dentation of nitrate-ion uranyl-ion are not shown. in complex. Equivalence of the IBP molecules reacted with uranylnitrate results into the equivalence of extinc tion coefficients of the =P=0...U02 bonds. If UOg (N0})2 TB1>2 complex con- taines two bidentate nitrate ions (Fig.2a) when third molecule of TBP joins to the complex removing of one atom of oxygen of nitrate-ion from coordina tion place takes place (Fig-2 ). Thus in the complex three coordinated bonds -И=0 (1529 cm) instead of two bonds appear during the joining of third TBP molecule. Buger-Lambert-Ber law validity for 119* cm"'1 band in the investiga ted concentration range was shown in /5/. From the spectrum of the solution 254 of mBrA m™ concentration of urauylnitrate CC^QprC^Q /-Q Ч ) ж 2|1 the extin ction coefficients of eW««»W>2 and -S=0 bonds were determined. By analy -1 sis of 1194 and 1^29 en bands the concentration of IB? coordinated (Сщр) was determined. The average number of ligands n in the complex was calculat ed by eos. (1): 0и , " тар О) *"П0, Xhe increasing of the XBF concentration in non-polar diluents is not ac- compained by qualitative changings of the IR-spectra /6/. lae cryoscopie and oamometric experiments /1/ show that IBP forma dimers and monomers. That is why m-spectroscopy method can not indicate association of TBF. Concentra tion of IBP monoirers /IBP/ was determined by the material balance of IBP tak ing into account aseotiation of ФБР. Material balance equations system gives: с хве + °TBP - тв! • ^°a <*°}h ^г ? <2 з JB finO) (g) As follows from the eqs, (1) and (2) the constant of the reaction D02 (H0j)2 5BP2 + IBP ж П02 (N0j)2 IBPj (3) is equal Я n - 8 00 (3 - S) 6&J Constants fi B, determined from the concentration curves of the optical density of sPaO...U02 and -Л=0 bonds have been founded to be equal 23+/-6 and 25+/-ЛЛ mol/dm^ respectively* Obtained data are in a good agreement with the results of the osmometric measurements Rl of the formation constant, where p a ж 3.7. One can explains greater value of the constants obtained in this paper by lower solvation capability of CIC compared with paraphines. + Equivalence of J>B obtained by analysis of ж P=O...Do| , and -H=0 bonds is indirect evidence the oxygen atom of the phosphoryl group of the third XBP molecule to substitute the oxygen atom of the nitrate group from the uraiyl- ion coordination sphere transferring the nitrate group from bi- to monoden- tate. References 1. Foczinailo Л., Danesi РЛ., 3cibona G.// J. Inorg. & Duel. Chem. 1973- Vol.35. M 9. P.3249-3255. 2. 'Hills A.L., Logan W.B.// J. Inorg. & Duel. Chem. 1964. Vol.26, M 12. P.2191-2193. 3. Stojanov E.S., Hichailov V.A., Obrazcova I.N.// In: Khimla vneshnssfernyh kompleksnyh soedinenij. lezisy Dokladov. Srasnojsrslc: SIBTI. 1983. P.76. 4. Grigoriev A.I.// Vvedenie v kolebatelnuju spektroscopiju neorganicheskikh soedinenij. II.: MGO. 1977. 195 P. 5. Ohvada K., Iacihara I.// 1. Inorg. & Hud. Chem. 1966. Vol.28, H 10. Р.23*3-23*5. 6. ?erraro J.B., Crlstallini C, Fox I.// J.Inorg.S» Hucl.Chem.1967 .Vol.29,N1. Р.139-14Й. 255 DIELECTRIC PROPERTIES AMD HATIIRE OP ACTIHIDES-TBP COHPIiEXES [~i-18~ I SOLUTIOHS IN NOHPDLAR DILUENTS I 1 M.A.Afonin, E. V. Komarov, V.v.Korolev, L.B.Sohpunt, V,A. Soherbakov, E.A.Kopylov. Leneoviet Leningrad Technological Institute, Khlopin Radium Institute, Leningrad, USSR The dielectric radiospectroscopy method enables in воше cases aide by side with determining the dielectric permittivity, in combination with other phy sico-chemical methods, to calculate ihe dipole moments of the arising chemic al forms, to determine the sizes of molecules and complexes having a nonzero dipole moment, and to judge on the nature of the solutions under study. TBP association in nonpolar diluents is caused by dipole interactions. In literature there ie no common opinion on the structure of TBP dimers» their dipole moment isn't known. The concentration dependence of the TBP benzene solution's dielectric permittivity, obtained on a modified apparatus "TBSLA BM-538" by us, «as processed by the developed by the authors Fortran-prog ram DIPOLE* The calculation was done with an account taken of the TBP dime- rizatlon constants obtained from osmometric experiments* The dipole moment of the TBP monomer P « J.28 ± 0.21 D, that of the aimer, F = «.45 ± 0.30D. Probably the dimers exist in two modifications: a linear "head-tail" one with a double dipole moment of the monomer E= 6.14 S (72%), and a "wood-pile"with a compensated dipole moment F в 0 (28%); it is also possible that the dimers form a configuration wherein tho angle between the dipoles' axes is 86+8°. Intermediate variants between the said alternatives aren't excluded either. The effect has been studied of the concentration of uranyl and thorium nitra tes on the dielectric permittivity of a 0.2 molal solution of TBP in benzene. It is shown that in the concentration range of uranyl nitrate from 0. to 0.086 mole/kg of CeHgi and of thorium nitrate, in the range from 0. to 0.078 mole/kg of CgHg, the. solution's dielectric permittivity remains practically unchangeable - 2.51 ± 0.10. In assumption that aide by side with monomers and dimers of IBP, in solu tion there are complexes of a sole composition Me(N0a;)r . TBPg, the dipole moments of the complexes were determined: Th (H0,}4 • TBPg P = 4.1? + + 0.25 B, U02 (H0j)2 • TBP2 P « 4.2 + 0.} ». There are obtained spectra of dielectric losses of the TBP solutions and its complexes with uranyl and thoriua nitrates in ben&ene. A resonance absor ption of energy is found at several frequencies. In the table there are pre sented experimental data and hydrodyaamic radii of the relaxing chemical forms calculated by the Einstein formula. On the basis of literature data Zl7 on the lengths of bonds between atoms and the angles between them, we calculated the distance R between the free ends of the radicals and a phos- phoryl atom of oxygen, equal 1.083 nm. Comparison of the values of S and Л indicates to presence of linear dimers of the "head-tail" type in the solu tion. The obtained results are used for creating a mathematical model of uranyl and thorium extraction by TBP solutions in benzene. Formation of a "11 organic phase" is a frequent phenomenon in extraction processes, in particular, in extraction of actlnlda salts. We have studied 256 the temperature-frequency dependences of the dielectric permittivity for the "II phase" containing thorium nitrate, IBP and dodecane, In the range of tem peratures 293-35} 2 and of frequencies 0.5-110 UEz. Concentration dependence of the viscosity (lp, the dielectric permittivity (£) and the resonance frequency (v) of ИР solutions at T = 898 К С. У, 4 aol/kg cps £ Й1Я C6H6 0.01 0.650 7.5 2.2* * 0.10 2.20 0.05 0.627 7.5 2.28 • 0.10 2.22 0.05 0.62? 50 2.21 • 0.10 1.19 0.10 0.666 7.5 2.5* • 0.12 2.1? 0.8 0.769 50 2.98 • 0.12 1.05 The decreases with growth of I in the low frequency range, while in the high frequency range the value of & increases with growing T. Thus an inver sion of the frequency dependence of 0 at change of T 1в observed. Presence of the inversion point may bear witness about coexistence of dif ferent forms of complexes of thorium nitrate and free monomers and aimers of IBP in dodecane, the relationship of their concentrations -hanging with a tem perature increase. At the same time the revealed temperature course of the dependence at dif ferent frequencies may be explained by presence cf two contributions into the value under measurement й>чУц u^), ahere the modules /£,\/+/£J i.e. by existence of the "11 phase" dielectric properties' anisotropy. Accord ing to the liquid crystal physics /&, I7.3aie.I607 257 SPECTROSCOPIC INVESTIGATION OP URANIUM COMPLEXATION IN THE MICRO-Г EMULSION SXSTEH OP HDEHP-n-HEPTANB B. (Nandi) Ganguly, S.N.Bhettacharyya. Nuclear Chemistry Division Sana Institute of Nuclear Physics, Sector -1, Block-'A?', Bidhannagsr, Calcutta-700 064, India Summary : Spectroscopic investigations of uranyl ion in the micro- emulsion system of HDEHP-n-heptane have been studied with respect to ics site solubilization, its micro environment and nature of complexation with the surfactant HDEHP. Introduction : The transport and concentration of uranyl ions and their coraplexation in a polar phase is an important phenomenon in the nuclear industry. Though uranium has been extracted with Di(2-ethyl hexyl) Phospho ric acid (HDEHP) in non polar solvents front acid leach liquors [\1 , the exact mechanism involved in the system has not yet been studied. Therefore attempts have been made to obtain spectroscopic information, of the uranyl ion interaction in the water-in-oil micro emulsion of HDEHP-n-heptane system. Experimental : A purified sample of HDEHP „was used for our experiments Uranyl nitrate, procured from Mallinckrodt Chemical Works, USA, AR grade was used. The other reagents used were of spectroscopic grade and triple dis tilled water was used for dilution. For fluorescence spectroscopy Perkir Elmer model 44B and for spectrophotometry Perkin Elmer model 554 have been used. Near IR spectroscopy was performed in Carry-17D by purging dry nitro gen into its optics system. Results -and Discussion : HDEHP is a strong surface active agent and finds wide application in extraction chemistry [l]. The formation of rever sed micelle and micro emulsion of HDEI'P in n-heptane in the presence of water has been described earlier /3/.. The extraction and incorporation of the metal ions vi.th.in the micro-water pools of these micelles have been depicted in various ways [k]'. "The incorporation of Ш5 ion in this reversed miceller system, its site, solubilization, its micro environ ment and the nature of complexation with the surfactant HDEHP can be probed spectroscopically* The emission spectrum of the uranyl ion in the HDEHP micro emulsion phase shows a definite resolved structure(Fifi.l) with its peak axima at 497,517,564 and 570 nm as compared to WAVELENGTH , the aqueous solution of uranyl nitrate F1K.1. Emission profile o'X at the same concentration when excited UO? in HDBHP/n-heptane sy at the same wave length 330 nm. However, stem containing 2% water In in tthis apolar phase their relative the form of micro-emulsion when excited at 330 am Intensity of fluorescence is hiphly (enlarged 3 times) 258 quenched which is found to be a result of ground state complexation. This complexation reveals a highly structured absorption spectrum o£ uranyl ion in HDEHP micro emulsion having different characteristics with 10 nm red shifted, highly structured intense bands with 2-3 fold increase in molar adsorptivity than the uranyl nitrate aqueous solution at the same concen tration. Thus fluorescence of uranyl ion in the micro emulsion shows a quenching effect. The plot of relative fluorescence intensity against the concentration of surfactant HDEHP(Fig.2) shows an ununiform distribution distribution of fluorescing species in the apolar phase. From our earlier results [з] it is presumed that water ir association with the surfactant polar head groups in the apolar phase forms araodifiedenvironment an d thus the HDEHP molecules can associate in diffe rent ways and swell in the presence of water. The combination mode of -OH band of water is affected by the insertion of uranyl ion in the polar domain(Pig.3). It is also noticed(Fig.2) in this case that the fluorescence intensity increa (0.01) £H O]/[HDEHP] ses in the beginning, then remains almost 2 Fig,. 4. Relative fluorescence inten- constant above 2M concentration ofHDEHP. aity ratio va.mole ratio of water The other observation shows (Fig. 4) that *» *» surfactant HDEHP in n-hep- tone the relative intensity ratio of fluore scence cenains constant upto a smaller mole ratio of [water] / [surfactant] and then increases as the water content is increased. Thus it can be con cluded that uranyl ion exists in the polar domain of the micelle and its spectroscopic properties are affected by complexation with HDEHP molecule and change of micro environment. References; fl] C. A. Blake, 'Further studies of the dialkyl phosphoric extraction(DAPEX) process of uranium', Oak Ridge National Laboratory, ORNL-2172. /"27 G. F. Vande<-rift and E. P. Horwitz, J. Inorg. Nucl. Chem., 42, 119 (198(7). /"3/S. N. Bhattacharvya and B..(Nandi) Ganguly, J. Collo Tnt"ntf.Sci.f , 110(1)— . ., .^15(1987 ) Л"••>---7 S. &". Bhattacharyy• a an- d• -B.(Nandi — ) Canpuly, Radioanal. Hucl. Chem., 98(2; 247 (1986), S.A.Kulyukhin, A.N.Kamenskaya, N.B.ldikheev. Inatitute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR The complex forming properties of uranium (III) have been studied insufficiently due to the instability of ita solutions. Shis work is concerned with the spectrophotometry study of the interaction of uranium (III) in various solvents with such crown ethers as 18-orown- 6 (18C6), dithia-18-crown~60iTl8C6)t dibenzo-18-crom-6(ПВ18C6), dicyoiohexyl-18-crown-6(PC18C6), 12-crowu-4(12C4)> 15-crown«5(l5C5). Using the Iv'-int erection scheme for the interpretation of the spectra of fd-transitions /j\,2j, we determined such energy characteris tics of uranium (III) аз the energy of the first unsplit level of the fd-сonfiguration 4^fd) and crystal field splitting parameter (A). Based on the analysis of these characteristics as well as on the study of the oxidation kinetics of uranium (III) certain conclusions about the formation of uranium(III) complexes with crown ethers have been drawn. In aqueous solutions uranium has been shown to be in the form of QlKlLO) J •?+, in this medium not any noticeable complex formation with 18C6, ПВ18С6 and DC18C6 has been observed. At the same time with 12C4 and 15C5 the half-oxidation period of uranium (III) increases (230, 200 and 150 h, respectively) in comparison with pure aqueous solution, though no changes of the spectrum of fd-transitions take place. Under these conditions the hydrated uranium ion may form sandwich complexes. In GRJJg solutions the formation of U (III) complexes with all the crown ethers under study is observed. The colour of the solutions changes from green in pure CH^CH to yellow in the ргевепсе of 15K5 and crimson in the presence of CD18C6. At the same time Д changes in the row: pure GH^CII > 12C4 >15C5 >DB18C6 J-18C6 ^-DC18C6. Hence, it can be concluded, that in the GH-,CN solution the uranium (III) comple xes with DC16C6 are the strongest ones. The same phenomenon is observed for the solutions in propylene carbonate, however, in this solvent the complex formation is more manifested. The analogous dependences are also known for divalent lanthanides. She uranium (III) complexes with sulfur containing crown ethers are less stable than those with the respective oxygen containing polyethers. References I.Johnson К.Б., Sand09 J.K.//J.Chem. Soc. (A). 1969» P.1694- 2. Kamenskaya A.N., Drodzhinsky J.t Mikheev N.B.//Radiokhimiya. 1980. T.22, M 2. S. 247-253. 260 FUNCTKHMUZED LIGANDS FOR THE SELECTIVE SEPARATION OF f- HETAL IOM& 5-21 p. A. Vlgato, p, Guerriero, S. Tamourlni and E. Bullita istituto di OMmico Tecnotogia dei Ri. ?elementi CNR Ceo Stati unit*, 4 35020 Padova - Italy Potentially pentadentate 6chiff bases derived from substituted sallcylaldehydes and triamlnes or diamines containing additional donor atoms in the aliphatic chain coordinate f-ions almost in their equatorial plane. A comparable coordination geometry about the f-iona was found with macrocyelic Uganda» containing the same coordination moiety, A serious problem connected with these complexes comes from their low solubility fn the organic solvents of industrial use (i.e. substituted xylenes). The addition of lateral chains to the schiff bases consi derably enhances the solubility of the related complexes in aromatic or aliphatic solvents. Thus the macroacyclic or macrocytic schiff bases Hg-I and Hg-H and the related lanthanlde(lll) and uranyl(vi) complexes have been prepared through the reaction schemes. 8 *—и W «.Ml m *-« at m НоугОЪ $~%>- U(HjlXNOjb № -4- ^ .А uo2(ii) .««ХИм. "Log^ H2(H) Ln(H2II)(N03)3 In the lanthanide(MI) complexes the Schiff bases behave as neutral pentadentate ligands. For the uranyKVQ complexes, owing to the presence of the linear O-U-O group, the apical positions of the coordination polyhedr* about uranium cannot be occupied by nitrate groups. Thus for the preparation of UO£(l) and UO2 is not present for the heavier ones. The complex иог(И) has been prepared in a similar way by template procedure, or by reaction of ио£<ноз}3.бн£о with the preformed ligand in methenol/chloroforet (using ыон). The aaymmetric complex, uOg(lll), has been obtained by reaction in methanol/dimethyi- formamide of the appropriate pre- - , "~\ cursor with 4-N-dode- / \/ _ /, cyldlethyllenetrlamlne. Hd- Юк н— (СЯ,)я—СИ* Preliminary studies on extraction * of f-iona from water into xylene and the subsequent stripping into water by means of the u- gands Hg-l or Hg-ll are very promising. иодш) ELECTROMIGRAIIDW STUDIES OF COMPLEX FORMATION REACTIONS OF NEPTUNIUM(V), AMERICIUM(III) AND CALIFORNIUMCIII) 5-22 Complex formation equilibria of carrier-free actinides 239Np(V), 2A1Am(III) and 249Cf(Iin have been studied in aqueous inert electrolytes at 298.1 К by means of a modified version of continuous electramigration measurements of v-emitting radio nuclides in homogeneous electrolyte solutions free of support ing chromatographic materials. Possibilities of the new analytical method have been demon strated using well-known oxalate complex formation of trivalent americium. Stoichiometric stability constants IgK^ and lgK* have been obtained in perchlorate solutions of overall ionic strength u = 0.10, D.05 and 0.01, respectively. Thermodynamic stability constants have been calculated. The values agree with the corre sponding literature data. Values of lgK^ of sulfatn - complexes of Am(III) and of oxalate complexes of CfCIII) have been obtained too. Investigation of the electromigration behaviour of NpCV? in neutral aqueous electrolytes yielded experimental dependencies a of type uV|D(V\ = f([L "]), L = oxalate, tartrate, sulphate, acetate, citrate. Mathematical treatment of these results lead to data of individual ion mobilities of the complex ions and of the stoichiometric stability constants, wich are not understand able if the well-known stoichiometry NpOj of the pentavalent neptunium cation is used. In contrary, a formal attempt to simu late the experimental data introducing a hypothetical stoichio metry NpO resulted in good agreements between experimental results and theory of electromigration as well as between values uf IgK^ calculated and literature data. 263 ACTIWIDE SEPARATIONS BY SUPPORTED LIQUID MEMBRANES I 5_23 P.R.Danesl. International Atomic Energy Agency, Wagrameratraase 5, P.O.Box 100, A-1400 Vienna, Austria Supported Liquid Membranes (SEJO consist of thin layers of organic solutions of water insoluble complexing agents (carriers), immobilized on nicroporous inert supports, interposed between two aqueous solutions. When the composition of the two aqueous solutions separated by the SUf is such that a chemical potential gradient exists across the membrane and the carrier is properly chosen, SLUs can be successfully utilized to perform selective separations' and concentrations of metal ions. As far as actlnide ions are concerned SLHs can be utilized for their separation and concentration prior to analytical determinations, for the treatment of low level nuclear wastes, or for controlling their release into the environment. In the present lecture some significant theoretical and experimental results of the work performed by the author and his research groups during the last few years on actiniae separations by SLKs are highlighted. The presentation is divided into five parts: a) Theoretical Aspects of the Transport Process through SLMs in Flat-sheet and Hollow-Fiver Modular Configuration. b) Application to Actinl4« Removal from PURKX Type nuclear wastes utilizing octyl(phenyl)-V*>-diieobutylcarbamoylmethylphosphlne oxide (CHPO) as Carrier, О Application to Uranium Purification from Lanthanides Using HDBHP as Carrier, d) Multistage Separation of Trivalent Transplutonium ions from Lanthanide ions wiht Series Of COBpOBite SUfB, e) Application of SLHs to Kinetic Studies of Slow Heterogeneous Liquid-Liquid Complexation Reactions of Actinides and Lanthanide Ions. a) Theoretical aspects of the transport process through д*« [Ц When the distribution ratio at the SLH-aqueous strip solution (initially devoid of actinides ions) interface is much lower than at the membrane aqueous feed solution (initially containing all the actinide ions) interface and the membrane phase polarity is low enough to make negligible the concentration of charged species, the ateady-stAte overall membrane flux can be derived by applying Pick's diffusion law to the aqueous boundary layer present on the feed aide of the membrane, to the membrane Itself and by expressing the interfaeial flux in terms of interfaelai kinetics. For linear concentration gradients we have demonstrated that the permeability coefficient of the membrane, P, is given by the aquation: P = J/C » •y ln 264 b) Application to actinlda removal from PURRt type nuclear wwtw by CHPO carriers 121 SLHB consisting of a solution of CHPO and TBP in decalin absorbed on polypropylene films or hollow-fibers have been studied for their ability to remove and concentrate aetinldes and lenthanideB ions from acidic nuclear wastes. The permeability coefficients of AD, PU, U, Ир, and all other major components of the wastes have been measured and the results interpreted at the light of our theory. The different contributions of aqueous boundary layer diffusion and membrane diffusion to the overall permeability have been evaluated for the various chemical species and for different membrane thicknesses. SLM stabilities and life-tines were also evaluated. The experiments have shown that the actinides can be efficiently removed to the point that the resulting solution can be considered a non-transuranie waste, i.e. it contains less then 100 microCl/g of disposed form. The process is characterized by the use of very small quantities of carrier, a high concentration factor of the actinides, low capital and operating cost and negligible solvent antrainment. c) Uranium purification bv HDfflP carrier Г31 HDllow-flber SIH modules have been utilized to study the purification of diluted uranium solution* In concentrated nitric acid from traces of lanthanldes ions. Commercially available hollow-fiber polypropylene modules have been used as supports, various process variables such as uranium, nitric acid and KDEHP concent rat ion, strip composition, pumping rate of the feed and strip solutions through the fibers, and module regeneration and reimpregnation, have been studied. The results, in addition to having further demonstrated the validity of our transport theory, have shown that ry proper selection of the process variables uranium solutions can be easily purified from lanthanides. The separation factor of the process, expressed as (Permeability coefficient of uranium)/(Permaability coefficient of europium} is 135. d) Multlataee separation of actlnldea from lanthanldoo by composite SCH tA| The permeation of Am and Bu through: (1/ a single composite SUf consisting of two complementary SUta in aeriea, separated by an aqueous solution of suitable composition, (ii> a series of such composite membranes interposed between compartments containing identical aqueous electrolyte solutions, has been studied. The two complementary Stile of the composite structure were a solution of HDEHP in n-dodecane and a solution of СИРО in decallno absorbed on microporous polypropylene films, separated by a 1mm thick aqueous slab containing nitric acid. The experimental results and their theoretical analysis have demonstrated trot in spite of the chemical similarity of Am and ft*3*, when M» of the Bu initially present In an aqueous feed solution {at the same concentration as As) is recovered with a series of 30 composite SLKs, a very high degree of purity is achieved. The purified Bu solution contains less then 0.011 of the initial Am. The equations describing the process are similar to those describing a linear chain of first-order irreversible chemical reactions. The permeability coefficients through each composite SUI can be easily calculated from the independently determinable permeability coefficients of the two membranes and the geometrical features of the system. 265 e) Applications of SLH to kinetic studies of actlnide and lanthanlde ions jS] Equation (l) can also be exploited to derive kinetic Information on the rate of chemical reactions occurring in a complex chemical system containing actinide ions. Be measuring the permeability coefficient and the distribution ratio between the feed solution and the organic liquid phase of the permeating ions, the pseudo first order rate constants of the chemical processes can be evaluated. 511b have been in this way used to derive kinetic infomation in faiphssic liquid systems containing HOEHP (SUJ carrier), polyamiiiocarbOKyllc acids (selective aqueous phase eoaplexmnt}, lactic acid (catalyst) and selected actinide and lanthanide Ions. The mechanism of the chemical reactions involved baa been elucidate! and separations of actlnides from lanthanides have been performed by simultaneously exploiting thermodynamic, kinetic and diffuslonal selactlvities. References 1. Р.Й. Danes!//Sep. Science and Techn. 19. 857 (1984-85). 2. PR. Danesi. B. ChUrlcU. P. Riekert and E.P. HorwitE//Solv. Rxtr. Ion Bxch. 3. I (1985). 3.. Д. Ramadan and P.R. Danesi, bo be published. 4. P.R. Danes! and C. Cianetti//j. Hemb. Science 20, 201 <1984) and 20, 215 (1984), 5. P.R. Danesi and L. Reichley-Yinger, to be published. MEMBRANE EXTRACTION OP TRANSURANIUM ELEMENTS PROM THE SOLUTIONS OP INORGANIC COMPLEX-FORMINC AGENTS A.P.Novikov, H.N.Mikheeva, B.F.Hyasoedov. Vernadsky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR Membrane extraction processes of inorganic substance» attract lately more and more attention of specialists- Membrane extraction is considered to be quite perspective method in comparison with its nearest analogue - liquid ex- raction owing to higher degree of element isolation from very diluted solu tions and, in some cases, more effective their separation. Besides, membrane extraction permits to use selective extractantB, not possessing high capaeity. The main quantity of research works are devoted to determination of technic and economic advantages of the method in hydrometallurgy of non-ferrous and rare metals. Concentration and separation of transuranium elements (IUE) by membrane extraction method have been studied in less detail. So the aim of the present work is a study of mass transfer processes through liquid membranes of a number of actlnide elements in different oxidation states and determina tion of the efficiency of these elements isolation and separation in compari son with liquid extraction in analogeous conditions. The kinetics of Hp(VT), Pu(IV), Am(VI), Am(IV), Am(III), Om(III) and Of(III) transfer through solid supported liquid membransB (SLM) ЛИ HDEBP, TOA, DO A, TOPO, TBP, ALQ-336, Primene-JUT and DOP solutions and emulsion membranes has been studied. Permeability coefficients of some actinide compounds through di fferent types of membranes are calculated. The most optimal conditions of TOE separation have been chosen on the base of data obtained. It has been shown, that the most effective separation is attained when using the method of ele ctrochemical /V and chemical stabilization of oxidation state of elements re moved through the membrane. There are three cases when membrane extraction is more preferable than liquid one: 1. Elements are quite etable in the gi ven conditions, but the selective extr- actant does not have sufficient capa city. For example, the technique of Am (IV) separation from TPE and other fis sion elements by extraction with BOA from sulfuric acid solutions, containing K10p2W17°6l ***' A/ is wel1 known. The low solubility of DOA salts even in po lar organic dissolvent is a substantial disadvantage of the method. The aplica- tion of membrane emulsion extraction al DOA M0f Я lows considerably to increase the deg Pig.l. Am(IV) extraction from 10"^ ree of Am(IV) selective isolation(Pig.2). PW( H S0 =1.5 H) solutions Nitric acid destroying phosphotungstate 2 4 a - DOA, CC1 - 3 M HNO, complex of Am(IV) with its following re J-. A — J JB 1U1V4 duction to Am(III) in receiving phase is emulsion, Ь - DOA solution used as reextractant In this system. 001. 267 120 180 t,fflin Pig. 2 • Semilogaritbmlc plot of Np(VI) Mg-3. SemilogBrithmic plot of Am end and Pu(IV) concentration те Cm concentration vs time,through time, through a HDBHP -0.111 HDEHP =0.1M SUt.t«e&:[«BO} -1H 4 4 SLM. Peeot!£HNOJ].1H,[Ffl-10" [H3PO4] »Ю" H, atriptiHKoj -m, II, Strip: I?HW03]' •1 H. 2. Ions of Isolated elements have the tendenoy to the reactions of dispropor- tionation. The extraction purification of Plutonium from microimpuritieo of Hp, or vice versa - neptunium from microimpurities of Pu, which is complicat ed by interaction of different lone forms in solution, can serve ав an examp le* However, using electrochemical stabilization and constant removing of im purities through the membrane, they manage to purify mioroeowBonent with high degree of purification (Pig. 2). 3, Isolated element is unstable in needed oxidation state or reduces by extr act ant. Separation of lain.) and Cm (III) is the most important example for practic. Am(Vl) reduces to Am(V) practlcaly by all extractanta. But, never theless, at almulteneous eleotrochemioal oxidation the part of Am(Tl) manages to diffuse through thin membrane (FlgO)» transmembrane flow being approxi mately one-tenth of calculated one under condition of Am(VI) stability. Thus, combining electroohemioal stabilization and membrane extraction they can iso late americium even when liquid extraction can not be applyed. References 1. Kosyakov V.H. et aW/Proo. I3EC-88, Moscow, 1988. Vol.4.P. 153-156. 2. llilyukova U.S. et aW/Radioohem. Radioenal. Lett. 1980. Vol.44. 7.259-262. 268 MODEL FOR TRANSFER THROUGH LIQUID MEMBRANES 5-25 V.M.Sedov, V*P.Kapranchik, V.V.Proyayev, A.A.Kopyrin. Lensoviet Leningrad Technological Institute, Leningrad, USSR Selective transfer through supported liquid membranes (SLK) is one of the most effective methods for separation of inorgania species.Its major advant ages /V lie in radioanalytical chemistry /57 and some areas of radiochemical technology, where pilot-scale equipments with Slil have been carried recen tly /37. Results of series of investigations give evidence of complicated relation of transport properties of 5ЗД and characteristics of ordinary liquid-li quid extraction in similar conditions- A mathematical model is necessary to use data on extraction for predicting SLU properties. Our approach differs from the certain models of steady-state diffusion- limited transfer through 5Ш £A7 in two respects: 1.By taking into account a great deal of chemical reactions in wuter and organic SLk phase in the form of law of mass action /g7; 2.Diffusion resistances for transfer in the external water phases are taken into consideration in the terms of diffusion layers for every chemi cal form. As result our model for any sets of reactions on the membrane interfaces and in the bulk phases can be expressed in the form of nonlinear equation set.Its roots are the chemical form concentrations which satisfy the follow ing conditions: a material extractant balance within membrane and material compound balance within bulk water phases; the law of mass action; continuty of the component flows on the membrane interfaces;condititon of zero current in the system* Compared with /V»°ur model allows to calculate the flow values of seve ral metals of different valency through SIM taking into account diffusion inside water phases* In case of Sill with organic acid as a carrier flow values as a function of hater phases composition,diffusion layer thicknesses in water and extra ction constant values were calculated.MetalMen+extraction reaction by an or ganic acid HS is written as; n+ + Me + HS s^r MeSn + H . Flow values J as a function of Log К without taking into account diffu sion layers (Fig. 1} for univalent metals agree with /V*F°? multivalent me tals expension of the plato region to smaller values of constants is obser ved. Our model differ from models described by allowing to calculate flow values of the metals competing for the carrier.For metals with the same valency SLU-selectivity is independent neither of correlation metal concen trations in the feed phase ^CMen+ ^ not of *ne aci^ concentration in the both water phases -5 pHf 3IBCM Xlg.1. J as a function of lgK without taking into account water diffusion layers. 1 - Me1*; 2 - Ие3+ Pig.2. J and Sia selectivity as a function of C^g whenlgK2=~3, lgK,=-2 Pig.3. J and SLM selectivity as a function of pH_ When separation of the di- and trivalent metal ions is carried out by S12L with cation exchange extractants SIK-selectivity can change as metal concentration correlation in the feed solution change. Plow values as a function from the extraction constants becomes hill character when diffusion lauers in water phases are taken into consideration (Pig.4). Unsiometrity for higher valency metals keeps. The flow value as a function from diffusion thickness has nonlinear character so change of diffusion layers results in new distribution component concentrations on phases separation boundaries. J.107mol/(sm2-s) 1.0H J-107mol/(sm*) 0.5 -» •» -г -I о 4 ~T~i « aeK о S ioo Fig.4. Jas a function of lgK, when diffusion layers in water phases considered. 1 - Me1+j 2 - Me3+ Fig.5. J as a function of diffusion layer thickness. 1-Me, + ;3-Me3+;lgK=0 This model can be used for SUI characteristics predicting. References l.Danesi P.R. // IS EC "88-. Papers. Moscow. 1988. Vol. III. P. 27-29. 2.1lovikov A.P.,Kyasoedov B.F.//Solv.Bxtr. and Ion Bxch. 1987. Vol.5. P.117 З.ОлОггак W.R. ,ITaser A. J.//Separ.Sc.and Techn. 1987. Vol.22.P.677. 4.Behr J.-P. et al.//J. Amer. Ohem.Soc. 1985- Vol.107. P.241. ^.SvseevA A.ll. ,l!ikolaeva L.S.llatomat.model.himich. ravnov. M.: MGU.1968. 270 SOLVENT FILM EXTRACTION IN THE DENSE CARRIER BED OP |5 ..26 A HIGH SPECIFIC SURFACE *-- A.YU.Vakhruahin, All-Union Research Inatitute of Inorganic Materials* Moscow, USSR An emulslonleas extraction process involving discontinuous feed of the aqueous and organic phases to a packed bed with a specific surface up to I0*ro /sr has been proposed. The bed provides movement of coming in contact phases in the form of solid mutually penetrating non-uniform thin films on the bed surface and intergrain spaces, Cocurrent extraction of the partition chromatography type incorporates mass-exchange between the moving discharging phase and the bed-confined accepting phase accompanied by eluting out the accepting phase Saturated with a component to be partitioned. With a cyclic counter-current flow through a bed packed with a mixture of water-receptive and water-repellent components, the accepting phase is alternatively filled up and eluted out by fresh portions of the discharging phases while a chromatographic front is moving along the column. Nitric acid and some actinide extractions under both conditions considered have shown an extremely high mass-exchange efficiency. The effect of the grain eize composition, the packing height and the sur face nature on hydrodynamics and short-term selective phase containment, and of the feed intervals on the mass-exchange efficiency» has been discus sed* 271 ACTIHIDE EXTRACTION РВОМ ГОСТЯМ ACID SOLUTIONS BIT ION FLOTATION I 5_2y S.A.Mezhov, A.V.Samatov, L.V, Troyanovsky. All-Union Research Institute of Inorganic Materials, Moscow, USSR It ia а common knowledge that to-day to extract metals from active efflu ents to meet the disposal standards the uae is made of tb? ion exchange sor ption method* However, being highly effective and selective the method has Significant disadvantages; among them the required fine pre-filtration of so lutions to he reprocessed, aalntenance of the particular acidity (pH of so lution) , difficulties in the utilization of spent sorbents and maintenance of a continuous process. Ion flotation suggested by F.Sebba £Yf can be an alternative to Ion sorp tion. The method is based on the chemical Interaction between an ion to be extracted and a surface active substance (SAS) - collector; this interaction results in the formation of an insoluble product. In this case a collector functioning as a precipitant of an ion to be extracted is simultaneously a hydrophobizing agent for the parti clef of the resultant precipitate. The hydrophobic nature of the surfaoe of the particles allows them to adhere to the bubbles of the air passing through the solution. The particles that es caped to the surface concentrate in a thin layer of foam above the solution from where the precipitate is removed as soon as it accumulates. The method is characterised by the relatively simple Instrumentation, efficient extrac tion, wide ranges of process parameter variations (in particular, the acidity of the solutions being reprocessed), the ability of solution reprocessing without filtration. As a colleotor we have chosen lauril phosphoric acid (LPA) known to be a strong ertrsetant Д?. The basis for the choice was our assumption that a certain analogy existed between the extraction and flotation behaviour of metals and that it is possible to use effective extractants as floto-reagents- colleotors. LPA is a strong complex former in acid media and the structure of the hydrocarbon portion of moleoules of phosphoric acid organio derivatives is responsible for their adequate surface active propertles- In the investigations the use was made of nitric acid solutions of thorium, plutonium(IV), uranlum(VX) and gadolinium (as an americlum simulator) having the concentration of the order of 50 mg/1 of the metal and 0.01-5.0 mole/1 of nitric acid. All the metals studied showed a significant influence of the LPA amount introduced into the system on the process efficiency; with the growth of the If A amount the extent of removal (<*.) of metal ions is monotonously increased independent of the solution acidity. At the mole ratio (J") of LPA/metal equal to 4, the extraction of thorium is ~10M, that of plutonium is £ 97* it the nitric acid concentration 0.1-5.0 mole/1 for thorium and 1-5 mole/1 for Plutonium, Ca(H0,)2 added to the system in the amount of 0.5 mole/1 does not significantly influence the extent of thorium extraction, however, the amount of EPA Introduced must be a little increased (toy »5) for the extrac tion to be comparable to that in the absence of the calcium salt. Uranlum(VI) Is extractactable to 95% from weak acid solutions (0.1 mole/1 of HN0,1 at ^•3, gadolinium is extractable to 99.9% from 0.01-0.1 mole/1 aqueous solut ions of mitrio acid also at Г «3. With a further increase of acidity of 272 gadolinium and uranium(VI) is observed to decrease; the decrease is especial ly abrupt for uranium(VI) (it is equal to 25% In 5 mole/1 of HNO-). An abun dant foam formation is characteristic of uranium (VI) and gadolinium at /KNO-/> 0.3 mole/1. Extent of removal (<*-) of thorium, plutonium(IV), uranium(VI) and gadolinium on mole ratio LP A/metal if) at different nitric acid concentrations (number on the curves)« For thorium and plutonium(IV) the values of «£. are averaged for acidity within 0-1-5 and 1-5 mole/1 HNO^, respectively. The high flotation extraction of plutonium(IV) and thorium can he ex plained by the propensity of alfcylphosphoric acids for the coordination with Me ions through the electron-donor properties of the phosphoryl atom of oxygen /*3? and by the low solubility of the resultant precipitates of Me alkyl phosphates even in concentrated aqueous solutions of nitric acid (up to 6 mole/1) /4,5.7- In case of uranium a decrease of t»C with an increase of HHOQ concentration is related to an increased solubility of a precipitate, uranium complex with n.lkylphosphoric acid /6/. As Is known trivalent lantha- nide and actinide ions are extraotable with organophoaphoric acids by a cat ion exchange /4/ therefore (by analogy) the acidity increased during flotat ion is likely to have a decisive effeot and results in a reduced extent of removal of gadolinium lona. References 1. Sebba P. Ion Flotation. Amsterdam; L.; K.Y. s Elsevier Publ. Co, 1962. 2. Uartynov B.V. Ekstraktaiya organ!cheskimi kislotami 1 ikh solyami. Spra- vochnik po ekstraktsii. Vol. 3. M* 1 Atomizdat, 1978. 3. Moskvin A.I. Koordinatsionnaya khimiya aktinoidov. M.: Atomizdat, 1975- 4. Sokhina L.P., Goncharuk L.V,, Solovkin A.5. // Radiokhimiya- 1981. Vol. 23. W 1. P. 82-87* 5. Solovkin A.S., Krutikov P.G., Pantelecva Л.Н. // Zhurn. neorgan. khimil. 1969. Vol. Hf If 12. P. 3376-3381* 6. Krutikov P„G., Solovkin A„s. // Ibid. 1970- Vol. 15, W 6. P. 1610-1613. 18.3акЛ607 273 ELECTR0MIBRA1IQN STUDIES OF INDIVIDUAL ION MOBILITIES OFl^S TRIVALENT f-ELEMENTS IN AQUEOUS ELECTROLYTE SOLUTIONS '——- G.V. Buklanov* „3 Dresden 6051, GDR; Absolute ion mobilities of carrier-free trivalent f-elements have been investigated by means of a modified version of contin uous electromigration measurement of «-emitting radionuclides in homegeneous electrolyte solutions free of supporting chromato graphic materials. We have studied dependencies of overall ion mobilities u~Me(III) of the carrier-free radioactive La(III), Eu(III), GdClII), Tb(III), Tm(III), Yb(III), Lu(III), AB(III) and Cf(III) on pH of aqueous perchlorate electrolytes, u = 0.10» T * 296.1 K. Informations on stoichiometric hydrolysis constants of the ele ments were available from the primar experimental correlations of tYPetrMe(HI) * f Values of the individual ion mobilities u£e3+ outside ol the hydrolysis equilibria Mere measured immediately. Surprisingly, two different levels of individual cation mobilities in neutral (pH > 5) and acidic CpH < 3) aqueous solutions were detected for the most of the cations investigated. Exceptions were Eu(III) and CfCIII). The interpretation of this effect should be found in struc ture changes of the electrolyte solutions and/or the hydrata- tions sphere of the migrating cations. On the other hand, relationships between the radii of the trivalent f-eleraents and their u|! }+ data in acidic as well as in neutral u = O.ICKCIQ^) electrolytes confirm the thesis of 5-shape changes of coordination number and hydratation charac ter within the trivalent lanthanide and actinide group ele ments Л7- Reference 1. F. David, J- Less-Common Met. _Ш (19В6) 27. 274 EbECTROmGRATIOU OF CARRIER-FRBE RADIOHUCLIDBS. ION ИОЫЫМ AND II HYDROLYSIS OF Hp(V) AJTO Ao(III) III AQUEOUS ELECTROLYTES SOHJTI0MaJ_LI F.Rosoh, Iran Kim Hung, ll.Hilsnov, V.A.KhalfcLn, a. V.Buklanov, R.Dreyer, R.Ludwlg, T.fielmann. Joint Institute for Nuclear Researoh, Bubna, USSR The ion nobility and hydrolysis of гз9Нро£ and 241Am3+ were investigated In perchlorate aqueous solutions by the modified low-voltage electrophoresis method [l>2] . Absence of finely divided fillers - oydrodynaolo stabilizers In the electromlgrstion сен, constant instrumental parameters and composi tion of background electrolyte solutions during measurements allow consider ing the experimentally determined ion mobilities as the absolute ones, their values depending only on the interaction of the migrating compounds with water and electrolyte ions. Ihe position of 239Hp(V) and ^'АШСШ) in the eleotromiBration oell at the given moment of time was determined by their /-radiation. Ihe radionuclide activities ware of the order of 105 Bq. She teohnique applied allowed observation of an earlier 'unknown effect, which Is most distinct for Hp(V) and Am(III): an increase In the ion electro- migration rate as the acidity of the eleotrolyte solutions decreases In the interval pH 3-5 (Figs 1 and 2). The relative increase in the mobility is about 50% and 25% for B"pO| and An3*, respectively. Fig. 1. Ihe mobility of Hp(V) Fig. 2. Ihe mobility of Am(III) plotted against pH of the back plotted against pH of the back ground electrolytes НОДОд-УаСДОд- ground electrolytes HClO.-HaClO,- NaOH, yU„ 0.1, SOg, 1 mmole l"1 NaOH, ,/W . 0.1 at 298.1 К and (O); NaOH, 0.2-0.5 mole l"1, 318.1 K. X 1* «*• oaloulated 1 M2H5OH 1 mmole I" (©)| 298.1 К curve Ihe maximum difference In the mobility of the Am3+ ions is aohleved at the ionlo strength J№ ^0.1. As Jjt decreasesv the mobility lnoreaaes both In acid and In neutral solution, and Rtjt ^Э"10~3 и^з*. - 7.0(25)« 10"* 275 C«W1 remains constant both In add ana in neutral solutions» Following our acta, we cannot reliable explain the reasons for tbe effeot found. But if one assumes tbat it is related to protohation of cations, -e.g. прО^пН-О* or Ат'+,пН,0+, it follows from tbe oaloulations that In both oases tbe pro- tonation*reaotion Is of tbe first order and tbe proton&tlon oonstants are 1 Kpr = 10* mole I" . Using the ourve йн^/у) s f(pH)» we oaloulated the hydrolysis oonstants and tho mobility of the complex hyeroxyl anion Hp(V) [}]: p_jB1 • 10.45(25), г 1 _1 pfi2 - 21.95(35). u°Bp0 иДшЗ+ s uta(0H)2+ s и.°л{0Н)1+ " 3 s г : 1 i our experimental data at pH >6»5 are satisfactorily oorrelated with tbe curve calculated by the hydrolysis constants 5A. » 8.02, p»2 = 14.62 and PjS m * 24.5 from Ref* [4] . We did not observe the anion products of the amerioium hydrolysis in strong alkaline solutions (pH^l 12.9). References 1. iUlanov M., Doberenz W. et al.//J.Raaioanel. Hucl. Cham. 1984. Vol.82. P.101. 2. lttlanov H., Iran Kim Rung et al.//RadlolchlBiya. 1987. Vol.29. P.650. 3. Roach ?., Hllanov M. ot al.//Hadiochimica Aota. 1987. Vol.42. P. 46. 4. Rai D., Strickert 0., Moore D. PKL-SA-10653, Richland UBH, 1982. 276 ANA1XSIS OF ACTINIDSS USING ORGANIC 1017 EXCHANGERS 5-30 | V-G-Dedgeonkar, Medhumite HUkherjee (fihattacbarjee) Department of Chemistry» University of Poona, Puna 411 007, India Ion exchangers find wide applications in the nuclear process industry, particularly in separating the fission products. f 1' 2) In continuation of our earlier worx^ ' and of others* on separation of transition metal ion exchange resin, we have studied here kinetics of uptake of uranyl and thorium ions by sulphonic polystyrene and polyaerylie ion exchangers. The resins were manufactured in India (Thermax Pvt. Ltd.) and used for these investigations. To follow the effect of radiation damage, studies were carried out after exposing these ion exchagers to varying ganma doses upto 9 ML.,. Diffusion co-efficients were determined using Boyd's equation and it is seen that the values are dependent on the size of the cation (see Table 1). The diffusion oo-efficients values were lower for uranyl ions as coopered to thorium ions. Due to radiation these diffusion co-efficients falls down fron 4,16 x ID12 в2а"1 to 2.52 x Ю12 n2s" in the case of uranyl ions and from 10.14 x 10 из" to 6.24 x 1). The higher activation energy also supported this showing longer time is required for its separation. 2+ i+ Effect of radiation on the diffusion rate of U02 and Th cations. Diffusion co-efficient values/10 m s~ at different temperatures System Temperature OMGy 4.5MCy 9H0y 2t vo2 15 1.95 1.02 1.79 20 2.66 1-55 2.39 25 4.16 2.52 3.15 30 5.60 3-81 4.57 4 та * 15 5.91 5-03 4.24 20 .'.88 5-99 5.17 25 10. H 7.12 6.09 30 12.46 B.95 7.23 277 logD -11.2 -11.5 -11.8 3.3 T4 3.5 10зл Radiation effect on the diffusion coefficient of exchanging systems. Polystyrene reain. Arrhenlus plots (doae:4-5№y) 1. Barghusen, J and Jonke, A.A., Reactor Fuel ProcesB, 8(2), 132, (1966). 2. Mason, E.A ana Greoky, A.T., Progress Chemistry, Pergamon Press, H.Y., P. 319 (1970). 3. Dedgaonkar, V.fl and Bhavaar, СМ., Int. J. Appl. Radiat. Isot., 22, 895 (1981). 4. Dedgaonkar, V.O., Ultra, S and Bhavsar, СМ., Radioehim. Acta, XL 113 (1982). 5. Zaki, А.В., Ind. J. Chen., Г7А, 544 (1979). 6. Boyd, G.E., Adamson, А.И and Hyars, I.A., Jr., J. AD. Chan. Sod fc?_, 2836 (1947). 278 ION-EXCHAHGE BEHAVIOUR AND SEPARATION OP TRANSPLUTONIUM ELEMENTS 5-31 lii UNUSUAL OXIDATIOH STATES IN MINERAL ACID SOLUTIONS L.I.Guseva, G.S.Tikhomirova. Vernadsky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR,Moscow,USSR Over the last two decade the methods of isolation and separation of TPK from a large number of other elements on ion-exchangers with mixed aqueous- -organic solutions of mineral acids have been widely developed £1,2^. Bat the high factors of intergroup separation are only for pairs Am-Cm and Cm-Cf while transcalifornium elements are not separated in this systems [2J* The most effective methods of TFE separation are based on the various oxi dation states of this elements in the solutions of the mineral acids fbj* The possibility of using organic ion-exchangers for the isolation end sepa ration of TPB ?n various, unusual oxidation states has-not been practically investigated* In this paper the behaviour of TPE on anion- and cation-exchangers in the solutions of HNO.jp H2SO^ and H-3PO4 in the presence of oxidants (KBrO-j, РЪОр, ^CrgOn, CNHWoSgOg) and in HC1 solutions in the presence of the reducing agents (Zn, Eu2+) has been studied. The nature and concentration of acids and oxidants (reductants) as well as the conditions of oxidation (reduction) and other factors has been studied in details. The effective methods of Bk(IV), Am(VI) and Md(II) separation from triva- leat TFE, REE and other elements with using anion- and cation-exchangers and solutions of HNO3, HgSO^, H3FO. and HC1 has been developed (Pig.1-3). O.OI-OJMH2SO4 8M HNOj 80 •* Am,Cm,Cf, 250 ff\ Es, Pr, Eu., 60 •If/II Cs,Fe eta. д. 40 20 1 \A 1 . 0 4 8 0 4 8 ml 0 4 8 0 4 S ml FlgH» Separation of 250Bk(IV) from Pig.2. Separation of Am(VI) from other elements on Dowex-1x8+Pb02 TPE and REE on Dowex-50x8 The distribution coefficients of trivalent TPE and the actinides in the higher oxidation states was found to differ the most considerably in the solutions of 1ЦРО4. It was used as basis for the development of methods for continuous, permanent isolation of isotopically pure Bk-250 and Np-239 from ite parents radionuclides Es-254 and Am-243, respectively. The ion-exchange methods are very suitable for determination of unknown oxidation states end some physico-chemical properties of microamounts ele ments with Z;?100. The peak position on the elution curves of the elements in Fig.3 show the mendelevium to be washed from cation-exchangers with Zn(Hg) as divalent element. Correlation of the peaks of Sr^+ Md2+ and Eu2+ and know- 279 ftCs 60 Еи 3 s40 /ш *У Cf.Eu * H 1 jj/lll MVM 2 4 6 8 ЧЫ), m HCI Pig.3. BLution curves of Md and otner elements with 1 И HOI from (—) Dowex 50x5 + Zn(Hg) and ( ) Dowex 50 without Zn log of the Sr and Eu + ionic radii allow to estimate the value of MdЛ*c dli, which can be used for the calculations of some physico-ohemical con stants of TFB microamounts /*4/. The data presented demonstrate that organic ion exohangers can be success fully used for isolation and separation of TPE both in higher and lower oxida tion states, as well as for studying physico-chemical properties of these ele ments in unusual oxidation states. References 1. Oaeeve L.I.,Tikhomirova G.S.,Stepushkina V.V.//Radiokhimiya. 1936. Vol.28. H4. P.556-560. 2. Usuda Sh.//j. Radioanal. Nucl. Chem. Articles. 1988. Vol. 123. H6. 7.619-631. 3. ttyaeoedov B.F.,beDedev I.A. //orit. Rev. Analyt. Chem. 1987. Vol.15. N4. P.3*7-394. 4. Guseva £*X.rTixhomlrova G.S.,Buklanov G.V. et al. //Radiokhlroiya. 19B8. ION-EXCHANGE ToETHODS FOR ISOLATIOJf AHD DETERMIHATIOH OP TRANSPIiOm 5-32 IIIUM ELEMENTS IN ENVIRONMENTAL SAMPLES L.I.Guseva. Vernadelcy Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR The problem of TPE isolation and determination in the different materials has been growing with its increasing production and the contamination of envi ronmental at the expense of global fallow, waste products of the atomic indu stry and some accidents. Two principal difficulties are arised when the analysis of environmental samples is carried out: the separation of raicroamounts of TPE from a large number of matrix elements and TPE separation from interferring оч-emitters of some artificial ai.d natural radionuclides (Table )- Some Nuclear Properties of TPE and other Radionuclides fI/2 Principal Erf, Nuclide T/2 Principal Et* , HeV years MeV 4.5-10' 5.49. 5.44 0.4 4_k 243, 7.9,103 5.28, 5.23 0.03 L7.1_.5_S 224 0.43 6.12,,_6_.07 p 0.09 L-7- 243 0 32.0 5^78^ 5 Л4 0.027 _.e._.J_I_. 244 c 18.1 5iS._5.78_ 0.02 245 3 fl: 8.2Ч0 5.36, 5.31 1-9 5-*3- 5.34 246- 3 3 4.7-10 5.37, 5.33 229„ 7.5-Ю 5.05, 4.97 **b0m 4.7.105 5.08, 5.04 231Pa 3.2-10* 5.0 2«0f 3.6-Ю2 5.8, 5.9 232ц 75 5.32, 5.27 25°0f 13.2 6.02, 5.9 "Spu 86.4 5.5, 5.46 The complex many stepped procedures including ..precipitation, solvent extraction and extraction or ion-exchange chromatography are used for purifi cation and determination of TPE in environmental p-4~j, that leads to the in- vitable loss of TPE microamaunta. Besides that in that analytical schemes TPE 225 are not separated from the Ac radionuclides. Meanwhile 'Ac as nail as the 227>228 227 228 223 224 daughters of Ac; » тп and » Re interfere directly with <*- apectrometric determination of TPE. In this paper the possibilities of TPE isolation and its separation from all accompanying and interferring elements with utilizing only one-two 1cm- -exchange columns and solutions of mineral acids ere presented. Cation-exchange column* The traneplutonium elements are strongly aorbed on cation-exchangers (Kd^lO3) from the mineral acid solutions if the acid concentration do not exceed 1 И. Hcwever a lot of matrix elements (Fe, Al, Ca, Mg, etc.) as well as the accompanying and int erf erring elements (RSB. Ac, Ha, Th, Pu, etc.) are aorbed by cation exchangers together with TPE. The верв- 281 ration of TPE from other elements is achieved by washing of the column with solutions of *. HC10.» HP, Н-ЛЧ)., ИС1-С2нд0Н and HOI. A significant shortcom ing of using of cation exchangers for separation, of TPE is dramatic decrease of TEE sorption in the presence of raacroquantities of other cations and strong complexing agents. This difficulties may be overcome by using anion-exchangers. Anion-exchange column. The aqueous-alcoholic solutions of nitric acid are the most suitable for concentrating of TPE by anion-exchangers, since only a limited number of elements (Ac, Th, Pu, Pb, Bi and REE) are sorted with TPBi More of that» the sorption of TPE from alcoholic-HtfOg solutions increases with the contents of the nitrates (Al, Pe, Mg, etc*/ [^J* This provides the possibi lity to concentrate TPE from the solutions of the complex salt composition. The separation of TPE from other sorted elements is achieved by gradient elu- tion with solutions of: 1 M HN0j-/90% CH3OH; 0.5 M NH4SGN - 0.1 M HC1 -80% CH3OH, 0.2 M 1Ш03 - 80% CH-jOH or 1 M HC1 - 80% CH3OII in depending of the compo sition of the analysed samples. The presented methods have the great advantages since the procedure of the isolation and separation of TPE from all other elements is carried out with one-two ion-exchange column only. This decreases the probability of loss of the analysed elements, shortens the time of the separation and the waste num ber and provide for the automation of the process. References 1. Gusmini B.//J. Radioanal. Chem. 1980. Vol.55, H.2. P.253-260. 2. Yamoto A. //J. Radioanal. Chem. 1982. Vol.75f N.I -2. P.265-275. 3. Balle3tra S. ,Fulcai R //Talanta. 1983. Vol.30, N.1. P-45-48. 4. Sekine K.,Jmai T,tKasai A./^Talanta. 1967. Vol.34, И.6. P.567-570. 5. Guseva L.I. .TikJiomirova G.S.,Stepushkine V.V.//J. Radioanal. Mucl. Chem. Articles. 1985. Vol.90, H.I. P.15-20. ION EXCHANGE OP URAHIUH(IV) IN IKDROCHLOHIC ACID- |Тзз ORGANIC SOLVENT MIXED MEDIA Zhao Aimin, Zhang Yanlin, Wang Luhuan. Department of Mordem Physics, Lanzhou University, Lanzhou, China Ion exchange in mineral acid-organic solvent mlxid media can be consider ed ав distribution of ions between two liquid phases having different com positions. This may be termed "combined ion exchange-solvent extraction" Ol* Helfferich £%7 and Marcus [$J commented on this problem In detail* Others reported their investigations on this problem as well, however they primarily directed their attention towards the investigation on the seperatlons, and the comparatively little investigations on ion exchange of U(IY) in mixed media have been reported though this is of great importance in both theory end practice. The anion-exchange behaviour of U(IV) In such mixed media as HCl-nethanol, HCl-ethanol, HCl-n-propanol and HOl-acetone have been investigated with strongly basic resin 201x7 (quaternary ammonium polystyrene resin, 7 per cent DVB, made in China) in detail in this paper; the distribution ratio of U(IV) D in, the systems mentioned above under various conditions have been measured; and the uranium (IV) species sorbed on the resin and in the mixed media have been studied by the visible and infrared spectroscopy respectively* The results show that: 1. The distribution ratio of U(IV) obviously increases in the presence of organic solvents* In conditions that the normality of HC1 in solution is constant (6K), the change of D measured with the Increase of the content of organic solvent (V?S) are showed in the following Table* Content of org. sol. D» distribution ratio of VO.Y), ml/g V5S HCI-CH3OH HCI-O2H5OH HCI-C3H7OH HOI-CH,OOOH3 0 1.20 1.20 1.20 1.20 10 3.60 6.06 3.76 11.9 20 17.5 28.5 12.9 48.0 30 60.4 85.6 46.8 143 40 163 107 125 52.9 That the decreasing of D «hen the content of acetone is beyond 30$ may be caused by the condensation of acetone by the aid of the catalysis of HC1. Besides, it le not found that D depends on the carbon chain lengths of or ganic solvents. 2. The visible spectra measured indloate that the species of U(IT) are different la the liquid and the renin phase. The increase of the organic solvent In the media promotes a further convertlon of the by drat ed ions of 283 U(IV) Into the oomplex lone D01J+ and ТГС1'+ Д/, and raises the distribut- Ion of U 3. The Infrared spectra of the resin 201x? wh^ch sorbed u"(IV) in various mixed media mentioned above show that the obvious absor ption peaks ooouring near the frequency 258 cm without exception have further proved that the U(I7) species sorbed on anion resin at the given conditions is UOlg" /6/. The intercity of absorption grows with the Inorease of the content of organic solvent in the media, it is entirely in agreement with the experimental data of distribution ratio D of U(XV). References 1. Korkisch J. // Nature. 1966. Vol. 210. ?. 626. 2. Helfferich P. Ion Exchange. New York: Mo Sraw-Hlll. P. 507-517. 3. Marcus Y., Sorters Л. s. Ion Exchange and Solvent attraction of Metal Comp lexes, John Wiley and Sons Ltd. 1969. F. 407-421. 4. Folcher G. et al. // J.Chim. phys. 1978. Vol. 75. P. 875. 5. Ryan J.L. // J. Phys. Cham. 1961. Vol. 65, P. 1856. 6. Kazuo Nakamoto, Infrared «id Raman Spectre of Inorganic and Coordination Componds, 3rd Ed. New York: John Wiley and Sons, 1978. P. 156. 284 SEPARATION OP АИЕН1С1Ш AND CURIUM OH САТГОЯ BCCHAHOER 5-3* WITH oUHYDROXYCARBOXYLIC ACIDS H.Vobecky. Czechoslovak Academy of Scienoes, Institute at Nuclear Biology end Radlooheaietry, Prague, Czechoslovakia The effective chromatographic separation of trausplutonium elements on cation exchanger depends on suitable choice of sorbent and eluting agent, in the previous comparision of separation performance of spherical cation exchangeres, the strong acidic cation exchange resin cross-linked with 8% divinylbenzene OETION LG KS 0800 (7-llpra, capacity of 5.0 msq x g" j has been chosen [ 1 ],. The experimental conditions for a thorough separation of a pair Am - Сю have been searched for using a llgand following a-hydroxyearboxyllc acldet a-hydroxyisobutyrio add (HIB) • Sommo activity Am » Alpho octivity ft Cf Eu •5 < iП A. 50 100 150 Elutlon drop number The separation of a mixture of 2*90f, 152Bu, Z*ZCm and Z"AB. The oolumn (45 mo x 2 am I.D.) packed with 0STI0N 1С S3 0800, eluant 0.36 H«-hydroxy ct-metnylbutyrate (pR 4.0), elution rate 1 drop per second,drop volume 25«1 [1] Vobecky M., J.Hadloanal. Duel. Chen., Letters, 105 (1986) 335 [2] Report 0RNL - 4247, Sept. 1968, p. 120 [3] Vobeckf M., J.Hadloanal. Nucl. Chen., Letters, 135 (1989) 165 UPTAKE OP ACTINIDES BY CATION EXCHANGE RESIHS IN PRESENCE 5-35 OP DETERGENTS AND COMPLEXING AGENTS H.H.Talah. Waste Management Department, Tajura Research Centre, Tajura, Tripoli, Libya E.A.KozHtin, A.S.PesMtov. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow,. USSR The effects of detergents and conplexing agents addition during low-level liquid-radioactive waste (LLRW) decontamination from actinide elements by ion-exchange technique has been investigated, radionuclide being used ae a pattern of actinide tetravalent state in aqueous solutions* Its concen tration in solution ranged from 4-0x10**' to 2.0x10 Ci/1. The adsorption behaviour of. on two ion-exchange re sine, KU-2 and VPK (strong aoidic sulphocationite and polyvinylpyridin-type chelating resin, both are of the USSR made, analogous DOV/EX 50x8 and HO02X A1, respectively) has been studied. Three types of detergents used In Tajura Centre special laundry ("Dixan", "Shamae'V'A.B.") and four complexing agents used for decontamination proce dures (oxalic and citric acid, disodiumethylenediaminetetracetate, sodium triphosphate) have been investigated. Distribution coefficients (K^). adsorption kinetic characteristics, column resource value, decontamination factors have been determined for detergent and coraplexing agent concentration up to 900 mg/l and pH value from 1.5 to 7.0. A strong dependence of 34Th adsorption on KU-2-resin in the investigated detergent concentration range has been observed - K- decreases from 2.0x10* ml/g to 0.7-10 ml/g. For VPK resin it appeared to be affected only in deter gent concentration range up to 100 rag/1 - the decrease in K~ is from 8.0x10^ ml/g to 3*0x10*^ ml/g„ and KD remained constant within the rest concentration range. Influence of complexing agents appeared to be less for KU-2 (the decrease in Kp from 2.0X10-3 to 4.0x10 - 6.0x102 ral/g). For VPK the complexing agents addition resulted in decrease in KQ value to 2.0x10^ ml/g in comple- xing agent concentration range up to 100 mg/1, Kp remained constant within the rest concentration range. The peculiarities in adsorption behaviour of г^**Тд have been discussed, taking into account the probability of complex formation and prevention of ion diffusion into resin grain due to the detergent film formation under the condition have been studied. The difference in effectivity of the decontamina tion of the two resin types is also explained. The considerable advantage of VPK-resin application prior to KU-2 for the treatment of actinides containing LLRW has been shown.. Analogous studies are being performed for **°Pu, *1Am. зовтоя or лохптж вьвтгаз BY IKOROANIC SOKBHITS 5-36 Т. В. Erylov, К. P. barina, G. I. Beulin. Khlopin Radium Institute, Leningrad, USSR Inorganic sorbents should Ъе used in the processes «herein these sor- bsnta manifest especially such properties as selectivity, radiation ohe- mioal and thermal stability. Separation and purification of actlnides fall into the oatsgory of these processes Д/. It is found that the oapaeity of zirconium phosphate in respect to actlnides and rare earth elements oould be inorsased by chemical modi fication of the sorsent /£, 37 »lth concurrent better absorption kine tics. So, the modification of zircinium phosphate by o^ioolinlc and di- glycollc aoids raises the sorption of Plutonium (IT) from 0,111 HHO» solution from 8.5 to 30 mg/6t and that of europium (HI) from 0.01 U HO, from 9.6 to "40 mg/g. On the basis of argon-adsorption investigation of zirconium phosphate structure, it has been proposed that the modification effect results in the formation of coarse and medium porous sorbente; this is to some de gree responsible both for increased capacity and for 2-2.5 fold in crease in sorption rate. She introduction of modifiers into reaction mixture during the syn thesis of ziroonium phosphate leads to the increase of relative content of phosphorus m0 • P/Zr from 1.5 to 1.6 - 1.9. It is possible that this is caused by substitution of organic Uganda for hydraxyl groups in the first coordination sphere of zirconium ions, which inhibits the deve lopment of zirconium polymerisation process, increases the reaction ability of zirconium forms in solution and gives rise ultimately to increasing me.- The sorption of trivalent actinides and rare earth elements decreases with increasing acid concentration; the maximum sorption of Plutonium (IT) is observed In 0.1 И Ш0-. Che dependencies of Am (IH) and Bu (III) distribution coefficients on the relative content of modifier during the synthesis of zirconium phosphate are of Bymbatlo'character. The close values of En and angle coefficients (3.0 * 0.5) of lg Kg - f (CH) function point to the dif ficult separation of aotinides and rare earth elements without the change of talent state; this is evident that the selectivity of modi fied zirconium phosphate is deficient. The modification effeot is stable under operating conditions with the use of sorbent) this is due to the absence of functional organic groups in aorbsnt composition. Ihe latter fact accounts for high radi ation ehemioal stability of zirconium phosphate. Thus, on irradiation of samples in 3.5 H HNO, by Co ^-quante within the range of doses 0 - 7-10 Gy, the composition and capacity of modified ziroonium phos phate with respect to plutoniun (IT), americlun (III) and europium (III) remain practioally unaffected. 287 Inorganic aorbenta based on phoaphatee and arsenates of vanadium sub- -group metals are among the leaet known; one of than, niobium phosphate /V iB more easily available and, owing to this circumstance, can have practical significance. The conditions for synthesis of niobium phosphates are investigated; method of slow gel-iornation la used specifically for the preparation of aorbent with reproducible properties. It la shown that the aorbent obtained possesses higher selectivity with respect to 4-eharged cations. For example, Plutonium (iv) ia effec tively abeorbed by niobium phosphate even from 3 M HHO- solutions. Annealing of inorganic phosphate sorbents involves, as a rule, de hydration, formation of pyrophosphates and various polymorphous transfor mations and brings about the decrease in sorption capacity. Hioblum phos phate is characterized by unusual dependence Кд • f (tan) for Pu (IT): decrease of Eg with increased temperature of aorbent annealing (tan) with subsequent sharp increase in sorption (maximum at tga • BOO °C). The spe cific surface of niobium phosphate changes in similar manner. Thermal processing deoreases slightly strength of the aorbent grains, but inoreases chemical stability of the material. The observed changes, are connected with structuring the initial amorphous (or eemlcrystalllne) niobium phosphate. The structure of aorbent subjected to thermal proces sing is studied by IR-spootroscopy and X-ray analysis. Sorption parameters, chemloal oompoeition and strength of niobium phosphate grains do not show essential changes under ^radiation (0 - 7.8.106 Gy) in 3.5 M HUOj. The investigation performed gives the posaibility to ijaprove conside rably the sorption characteristics of studied inorgania aorbents and re commend them for group separation of actinides and rare earth elements (the modified zirconium phosphate), as well aa for separation of aotl- nidea with different valency (niobium phoBphate). References 1. Barsukova К. В., Myaaoedor B. P.//RadioMiiaiya. 1981. T. 23. N 4. S. 489-493. 2. Krylov T. U., Larina E. P.//Radiokhlmla. 1988. T. 30, N 5. S. 633-636. 3. Erylov V. H., Larina E. E.//Radiokbimia. 1988. T. 30, N 5. S. 636-641. 4. Deulin a. I., Sgorova N. В., Krylov V. N. et al.//zh. prikl. khim. 1981. T. 36, H 6. S. 1226-1331. 288 PROGRESS ТИ ACTIS1DE EXTRACTION CHEMISTRY I" A.M.Rozen. All-Union Research Institute of Inorganic Materials, ' Hoscow, USSR The last decade is characterized by intensive developments of new extrae- tante for actinides recovery to improve fuel reprocessing or for analytical chemistry. As is known the disadvantage of trioutyl phosphate - the main oxtractant in radiochemical prooeeses using saturated hydrocarbons as diluents is the second organio phase formation even at moderate concentrations of plutonium or thorium. A.S.Hikiforov, the author of this review et al suggested as an alternative trialkylphosphates with the optimized hydrocarbon chain - the elongated one - and the iaoatructures triisoamylphoephate (TIAP, nc = 15). diisooutyliaoootylphosphate (nlBIOP, nc-16)and oth.Q.-4). TI«P has an adequate capacity for Pu, it is by a factor of 20 less soluble as compared to TBP, in an aqueous phase, but forma the second organic phase with Tht DTBIOP and THP are free from those disadvantages* Theae extractants were successfully tested in a centrifugal extractor cascade reprocessing fuel of up to 100 GW day/t burn up at the solution activity up to 1030i/l (5] ,(see also Hikiforov A.S. et al,at this conference). In the USA for similar purposes Arnold and Crouse suggested triiaooctylphoaphate (TOP) [6] and then also trialkyl phosphate se ries including MAP. TOS was tested in hot cells, a method was developed for removing acidic hydrolysis and radiolysis products (D2BHPA): the disadvantage is a limited usable concentration 4 0.5 mole/1 [6] . The alternative to TBP is also amides of carboxylio adds RC(0)HR£. Some data on U,Pu,Np extraction are given by B.N.Laskorin et al p] • Tn the extrac tion chemistry amides are aimilar to TBP,but have a lower extraction ability* The investigations by the Italian (Caaarbi.GaspaAni.arossi) and French (Mu- eioaa, Germain) scientists lead to a flow sheet development for the 1 extraction cycle (0.9] t diamldes are suggested for Am extraction Q9j.The advantages of amidoa are the relatively weak influence of degradation pro ducts on the process and a higher selectivity that permits uranium and Pluto nium separation without a reducing agent for Pu, a higher purification of va luable elements from fission products* At the same time a poorer (oompared to TBP) compatibility of actinlde and nitric acid solvates with hydrocarbon di luents is observed. By varying the amide structure the compatibility can be improved,however, conditions that eliminate the third phase formation are to be refined. The U,Hp,Pu extraction with traditional extractants (neutral ones, acids, anines) see the reviews Do,1y • It should be only pointed out that investi gations into the extraction with zirconium salt of D2EHP' were in progress* Zr introduction into D2EHPA significantly improves extraction, particularly, of Pu [12] . In the USA and the USSR actinide extraction has been studied extensively, especially that of transplutonium elements (TPE) with bidentate organophos- phorua compounds* In the USA Horwltz and Sbulz have atudled extraction of Am and other elements with a great number of carbamoylphoaphonatea (CUP), carba- moylphosphine oxides (СИРО)* For praotical purposes (TPE extraction from ra- 1Э.Зак.1607 289 diochemioal process rafflnatee) СЫРО oot PUKOJOR^OCHdtiujg is recommended and a flow sheet TRUES has been developed that envisages the use of this ex- tractant (0.25 mole/1) with 1.0-1.5 mole/Z IBP added as a aolubilizing and synergetic agent; the process incorporates extraction and scrubbing (Zr and other PP are bound with oxalic acid) > Лш stripping with weak IfflOj and that of Pu - with HHO, with HP addition [13] (the same flow sheet but named TESEO has been suggested by Casarci et al, p4J )• Recently Horwlta has also suggest- ed a version of his flow sheet TRUEX-chloride for chloride media suitable for the dissolution of metallurgical waste [15} In the USSR extraction of «ctinides was studied using CHK> and diphosphine dioxides (DPDO)R2P(O)(CH2)n(0)PR£ (see $&]). In 1975 Rozen A.M., Hikoloto- va Z.I., Kartasheva tt.A. found out [17] an interesting effect - the anomal ous aryl strengthening (MS) of DPDO - actinlde complexes. Tha anomaly lies in the fact that on replacement of alkyl aubstituents В with more electrone gative aryl ones (XR=2.0; xpn=2.35) when the oxygen electron donor properti es (and extraction with all monodentate compounds or with DPDO, but with mo- nodentate coordination) deteriorate, the actinide extraction with DPDO and CHPO characterized by a bidentate coordination and a cycle formation, on the contrary, is greatly improved. The cause is electron density derealization from aryls into a complex cycle and, possibly formation of a conjugated bond system la a cycle: AAS practically disappears when a methylene bridge elonga tes to ethylene one but recovers on its replacement with в vinylene one CH=CH fie] (for more detail see the paper of the authors this conference). The AAS effect is useful for the procees. The extractants recommended for practical purposes, i.e., tetxatolyl DPDO and CMPO tolgP(0)CH_(0)CNbu2, have been suc cessfully used for PR fuel reprocessing (burn up of 100 OW day/t),aee the pa pers of Wiisiforov A.S. et al, at this conference. A series of tridentate ext ractants have been also investigated. More than 60 CMPO, DPDO and other a have been studied in the work of Hya- soedov B.P. et al, [19] ; to improve the selectivity rigid bridges-fragments of a benzene ring were used; it is found that on introduction of two CHgP(o)Ph2 groups in the orto-posltion the selectivity for U/Am and Pu/Am pairs is in creased. Replacement of one of the methylene bridge hydrogens with different radioals resulted only in a decreased extraction. An interesting property of CMPO was found out by llusoatello,Navratil et al.: СИР0 extraets effectively Pu polymers inextractable with TBF [20]. Z.K.Karalova et al. [21] found extractants for TPE from alkaline and car bonate media (alkyl pyrocateehins, amines, 1-phenyl-3 methyl-4-benzoyl pyra- zolone-5(PMBP)). Рог TPE separation it was reoommended to oonvert some of tnem to unusual oxidation states with the subsequent separation by extraction [22] , Two-phase aqueous systems on polyethyleneglycol base are also of inte rest for analytical ohemistry [2jj. For the prediction of extraction ability (EA) it was suggested to use a quantum- chemical calculation of the electronic structure of extractants, their proton affinity or the energy of the H-bond with H,0 |24-2б] . This ap proach allows prediction of E» even when the influence of substituenta in an extractant molecule is essentially not additive and therefore the traditional methods of prediction (the electronegativity method [27] the Hammet-Taft one, 290 use of Kabachnik constants С?*9* [28] become helpless. For instance, a ohange in Ш in the ketone-amlde-urea series when the introduction of the first amide group improves uranium extraction by three orders while the introduction of the second one gives nothing |&5»2&)is not understandable based on the tradi tional approach,' but from the quantum-chemical viewpoint oan be adequately explained. References 1. Rozen A.M., Nikiforov A.S. i dr.//AS SSSR N 841140 (prioritet ot 7.02.80). Byull. izobr. 1982. N 14. S.319. 2. Nikiforov A.S., Shmidt V.S., Rosen A. 11.//XII Mendeleevsky s'ezd. Referaty dokladov. M.i Nauka» 1981. 1.1. S.188. 3. Rozen A.M., Hikiforov A.S. i dr.//Dokl.AN SSSR. 1984. T.274. S.1139. 4. Rozen A.M., Nikiforov A.S. i dr.//At.energiya. 1985. T.58. S.38. 5. Nikiforov et al //ISEC'S8:Papera. Moscow. 1988. Vol.IV. P. 168. 6. Orouse 1)..Arnold W..Hurst F.//ISEC'83sPapers.Denver Colo.1983.P.90. 7. Laskorin B.N. .Skorovairov D.I.jPilippov E.A..Yakshin V.V. i dr.//Radiokhi- miya. 1985. T.27.S. 156.ISEC'88.Papers.Moacow. 1988.Vol. 1.Р. 145- 8. Casarci M., Gaaparini G., Grossl G. et Bl.//ISEC'8S!?apers.;iunchen. 1986. Vol.1.P.107. 9. Husicas C, Germain U.//ISJSC'a8:Papers.Moscow. 1968.Vol.IV.P. 124. 10. Rozen A.M., Nikolotova Z.I.//Radiokhimiya 1988. 1.30. a.594. 11. Nikolotova Z.I.//J3kstraktsiya neitral'nymi organioheskimi soedineniyami. Actinidy. Aotinidy. Spravochnik. U,:Energoatomizdat^ 1987. 12. Sinegribova O.A., ragodin Q.A. i dr.//Radiokhimiya. 1987. T.29. S.174. 13. Horwitz E., Shulz W.//ISEC'86:Papers.Hunchen.1986. Vol.1.P.181. 14. Qasarci И. et al//IS£ClB8:Papers.Hoscow.i988.Vol,Iv.P.219. 15. Horwitz E. et al//Solv.Extr. and Ion Kxdh. 1987. Vol.5. P.447. 16. Rozen A.M.,Nikolotova 2.I.,Kartasheva N.A.//Radiokhimiya.1986.I.2S.S.407. 17. Idem // Dokl.'N SSSR. 1975. T.222. S.1151. 18. Rozen A.M..Nikolotova Z.I..Kartasheva N.>.//ISEC88. Papers.Koscow. 1988. Vol.IV.P. 133. 19. Myaaoedov B.P.//ISEC,88:Papers.Moscow.1988.Vol.IV.P.1 IB. 20. IJuscatello A.C.Navratll J. et al.//Separ.Sci.Teclmol. 1983-Vol. 18.P. 1731. 21. Karalova Z.K. i dr.//RadiokMmlya. 1987.1.29.S.335,767:1988.1.30.S.2O3. 22. llyaaoedov B.P..Lebedev I.A.Radiochin.Acta.1983.V.32.P.55. 23. Holoclmikova B.P.et al.//ISE0'88:Papers.Mosoow.1988.Vol.IV.P.l47. 24. Rozen A.M. .Klimenko N.U.,Krupnov B.V..Nikiforov <.S. Dokl.AN SSSR, 1986. T.287. S.915. 25. Rozen A.H,/*TSEC'88. Papers! Mosoow. 198S. Vol.1. P.62. 26. Rozen A.M., Klimenko U.M., Krupnov B.V.//TSEC88. Papers. Moscow. 1988. Vol.1. P.70. 27. Rozen A.M..Nikolotova Z.I. Zhurn.neorg.khim.i964. 1.9. S.1725. 28. Rozer. А.И., Konstantiniva N.A./bokl. AN SSSR. 1966. T.66. N 1. 2»1 HAIHEHATICAL UODELLIHG OF ACTHIIDE EXTRAOIIOH EQUILIBRIA ADD Г 5-38 | EXTRACTION PROCKSSES ' A.H.Rozen, V.n.Rublsov, V.S.Vlaaov. All-Union Research Institute of Inorganic HaterialB, Moscow» USSR attraction equilibria* The mathematical modelling of extraction equilibria on the masaaction law base is both the stage of process mathematical model ling and the method of extraction chemistry investigation. For control purpo ses aimplier empirical models can be also used. If the reaction chemistry is given by HeZ+ +ZA" -tqludteAgL » the concentration in an organic phase will be: yjle-ЖХщ pLl'^L'-fb*, where tb£ff is the concentration (R is effective) cons tant of the extraction equilibrium, f^ is the activity coefficient of a salt in an aqueous phase) Ь is the concentration of a free ligand LsL -.Sq^y^ where q. and Уч"^ь •*» solvate numbers and the concentrations of the com pounds extracted* By solving the system of equations one can find the free extraotant concentration h and all y,- Using this method the extraction iso therms for the system uranyl nitrate (for which jf+ is known)- НЯО3 TBP were first described» and the extrema of the nitric acid dependences of actiniae distribution coefficients were explained [1]. In a general case to model equilibrium one should know the extraction constant on composition (ionic strength J) dependence» 1-е*» in fact to predict or describe the aotinity co efficients in electrolyte mixtures. Since In !?=lnK+ 9ln]f+ and according to the Debye Hfiekel theory Ц" «f(V3) in [2] we used the InSS S.e^iK,z expansion and described the distribution coefficients for V and microamounts of Pu(IV) and (VI), Np(IV) and (VI). Later on wo have refined the chemistry of the nit ric acid extraction - formation of hydrated disolvate and semi-eolvate along with anhydrous monosolvate HUO^.TBPfj] .The models cere refined for U(VD,Pu(E) Pu(IV),Pu(VI,,Hp(IV),BpiVlKire managed to estimate the activity coefficients,de termine !c as К J*_J and find the К dependence on the n-hydrooarbon diluent type) For actinide (IV7 macroamounts included empiric dependences are suggested Щ - But the technecium.distribution model was again constructed theoretically; HTcO.(H20)* IBPjcomplex formation as well as co-extraction of Tc together with U,Pu and Hp were accounted for [5] «The activity ooefficlents in electro lyte mixtures were calculated according to the Kozen rule with the effective ionic strength introduction describing the deviation from the common ionic strength rule Q>] «Recently the more rigorous Mikulin rule has been used that is based on the isopiestic solution laws.Thia method made it possible to de termine the activity ooeffioients for lanthanide and americium microamounts ( If+Am" the oonstants of Th(M0j)4 extraction with 3WB? in a diluent.Extraction con stants were found for ?h as di- and trlsolvatea (K2»3.2,K,«1440) using these constants all the experimental data known were described with the accuracy up to 10& (some refinements and the broader acidity range with account for 292 acido-complex formation) .To estimate Jf± and K^ Solovkin aemi-empirical equ ations were also used to calculate the activity coefficients of individual ions [8] which is particularly convenient for the complex formation descrlpt- ion.Finally,for quiok calculations (e.g.,in control systems) a more simple model has Ъееп suggested:by processing a large array of experimental points (2500) regression equations bave been derived for U,Pu,irp,HHO? distribution coefficients on extraction with a 30% ТВ? solution in hydrocarbons.The maxi mum polynomial degree is 3,the number of tenns is ^ 20. Process modelling. To model a steady-state extraction process in a mixer- settler cascade it is sufficient to have equilibrium models; the model [2] was shown to adequately desoribe the data of different authors.To describe tran sient prooesses one should know the flow structure where the dependence of the emulsion layer height on the load and physico-chemical properties is most complicated.The DYHS-83 programme |Hl] takes account of the above factors.To describe reduction stripping data are needed on the prooeas kinetics.In this way plutonium stripping was calculated using Fe(II) and an idealized process with U(1V) ft2*13j,parasitic reactions neglected.The refinements involved Pu(lII) .hydrazine ]J4j and U(TV) ^5] oxidation with nitrous acid аз well as U(IV)-Tc interaction which is especially Important for №Ш fuels when Tc con tent is rather high {13}.The corrections are significant,make it possible to understand and describe the actual procees.The approach to the reality is also reached through the calculation of U and Pu stripping with account for dibutylphosphoric acid [16] that inhibits the process at the end stages.final ly on the basis of the models [8] it beoame possible ф] to describe Pu ext raction afflnage with regard for the hydrolysis and complex formation with organic (CHjCOOH.HCOOH) and inorganic (HgS04) Uganda. Thus.it is possible to model reliably all the stages of the extraction pro- ceas.This permits the use of mathematical modelling to optimize the process under development as well as to analyze accident conditions from nuclear sa fety viewpoint. References 1. Rozen A.M.//Atomn.Knerg.! I957.T.2.S.445. 2. Rosen A.M.,Zel'vensky M.va.//Radiokhimiya 1976.T.18.S.572. 3. Rozen A.M.,Andrutsky L.G.//Zhurn.neorg.khim.1982.T.27.S.2089. 4. Rosen A.M.,Andrutsky b.G.,Vlasov V.S.//Atomn.energ.1975.T.62.S.227. 5. Rozen A.M. i dr.//Atomn.energ.1967.63.S.175. 6. Rozen A.M.//Zhurn.fiz.khim.1976.T, 50. S.2012. 7. Rozen A.M.,Vloaov V.S.,Andrutsky L.f-.//IS£C'88.V.2.P.336. 8. Solovkin A.S. i dr.//Atomn.energ. 1984.T.56.S.406. 9. Solovkin A.S.,fiubisov V.N.//Atomn.energ. 1984.T.56.S.406. 10. Petrioh G.,Kolarik Z.//KFK,2536.1977(1978,9,H 14-Atomindex). 11. Vlasov V.S.,Rozen л .M.//nyMS-83.Preprint AUSRIIM, P -2(35),1983. 12. Rozen A.M. i dr.//Atomn.anerg.1975.T.38.S.367. 13. Rozen A.M. i dr.//Ieor.osnpvy khim.tekhnol.1976.T.10.S.105. 14. Petrioh G.,Schmleder H.//ISEC'83.Paper.P.84. 15. Harohenko V.I. 1 dr.//Atomn.eDerg.1987.T.63.S.88;1989.T.66.S.4. 16. Rubisov V.N., Solovkin A.S.//Atomn.energ. 1987. T.63.S.23. 293 THE игашшлгон os HITRIC AOT» AHD ACKHIDBS ^IH 5-39 URANIUM Iff TBP-PHASB DURING EXTRACTION В.Ya.Zilberman, Yu.S.Fedorov. Khlopin Radium Institute, Leningrad, USSR Aa It has been shorn earlier, on extraction of Ш0, into TBP satu rated by uranyl nitrate and equilibrated «1th Its solid salt, the dis placement of uranium from the organic phase dose not occur, while TBP- uranium ratio remains aonstant and approaches 2 /l/. НЯ03 is supposed to be extracted by U02(H0,)2-2TBP. It «as shown as well /г/ that the extraction process of actinides into XBP saturated by uranyl nitrate exhibits some distinctive pro perties and in particular the great difference in distribution coef ficients of tetravalent Up Bad Th. IR-apectra of HHO- In те>2(ИО,)2«2ТВР presented to this work have no characteristic frequencies of НПО••TBP monoaolvate (Table). It po ints to the absence of uranyl nitrate displacement by nitric acid from UOQCNOOQ'ZTBP and the absence of uranyl trinitrate complex in the or ganic phase. Otherwise the liberation of EBP molecules in the case of н[ш>г(1Ю-)Л'ГВР formation and henoe the appearanoe of НПО у TBP would take plaoe. Vibration frequencies of HNO, and U02(N03)2 for nitric acid solution it UO2(NO3)2-2TBP, i» го °c, ioo % тар Uolar ratio Subs Vibration TBP HHOj'TBP йяо3 шо :ш сио ) -гтвр tance modes 3 г 3 2 0:1 1:1 2:1 4:1 IBP Valence, P = 0 1282 1200 - 1189 1175 1173 1170 Valence, OH-groups 2640 3600 3600 HN03 - 3600 - 3600 НПО j Assymetr,, N02 - 1647 1675 - 1673 1673 1673 НПО, Valence symmetr., - 938 925 - 910 910 910 NO Valsnoe, КО 1542 DOg(H03)2 --- 1523 1534 1537 пог{яс3)г Valence, H02 --- 1280 1265 1265 1265 Assymetr., U0 946 ио2(ж>3)2 2 --- 933 942 945 Tho dissolution of HHO, in ио^ЖО^гТВР according to frequency chan ges cited in the Table may be realized with equal probability through ШГО, hydrogen bond with oxygen of nitrate group of uranyl UOgCOgNOJj'STB! -HHOj H0H02 or with phosphoryl oxygen of TBP: )Р-О(Н0,)20ги 0=pj- The concentration dependence of PuQY) and Up &Y) distribution coef ficients (D) in extraction by 30 % TBP-dodecane is found at concentration of uranyl nitrate aqueous solution beginning from 80 g/1 and higher (Pig. 1). The Dj,u values at concentration of Pu(IY) up to 0.2 g/1 are in ?94 compliance with the data [y recalculated for 30 S6 IBP; the B^ values at concentration of Pu(IY) in aqueous solution above 3-5 g/1 agree with the data /t, 3j recalculated for 20 °0. ИГО» concentration exerts prac tically no influence on this dependence. In ease of Th such dependence is not observed up to concentration 40 g/1. !Phe correction for the model /б/ taking into account this effect can be expressed by the equation: > \ where К , К are concentration constants of Fu extraction, with correc tion and by model p>] respectively; Xg> Xpu are respectively the con centrations of U(T1) and Pu(IY) in aqueous solutions: A - constant. From the temperature dependence for Hp(IY) (Fig. 2) it is evident that the entire increase of D_ with the growth of its concentration in the aqueous phase within the interval 0-60 °0 at constant values of X» and XJJXQ is associted with entropy change. (This confirms non-che- mioal ohareeter of the interaction described above. 103/T X,„,g/l Fig. 1. Extraction of tetravalent Pig. 2. Temperature dependence of aotinldea by 30 % TBP in dodeoane at Hp(IY) extraction by 30 % ТВГ in 1=20 °0. Xg»100 g/1, Хдо -в «/-• dodecane. Хц=220 g/1, XJJJQ =2 St/1. 1 - Pu(IY); 2 - Hp(rf); 3 - Th(IY) %p=3 s/1; 2 - %p=0,1 g/1 References 1. Fedorov Yu. 3., Zllberman B. Ya.//RsdiokMmla. 1986. I. 28, 11. S 36. 2. Fedorov Yu. S., Zilberman B. Ya.//Ibid. 1988. T. 30, N 4. S. 572. 3. Hoiseenko E. I., Rozen t. M./ZRadiokhimia. I960. I, 2, Я 3. S. 274. 4. Vereshchagin V. В., Benard E. V.//Atom, energiya. 1978. T. 44. N 5. S. 422. 5. Petrioh в., Kolarik 2. //КГк - 3030 (1981). 6. i-огеп A. M., Zelvensty M. Ya.//Radiokhimia. 1976. I. 18, Я 4. S. 572 295 THE INFLUENCE OP DILUENT OP TnCl4 *~*j „„-.~^w« . . ENERGY WITH TBP MOLECULES IK EXTRACTION SJfSTEM TBP~HC1 I I.Kulawlk, J.Kulawlk, J.Mikulakl. Institute of Nuclear Physics, Cracow, Poland It is known that in the ease of extraction process the distribution coef ficient of species decreases with the decrease of extracting agent concent ration in the organic phase. The extraction process accompanied some pheno mena appearing at the Interface of extraction system e.g. electrical distri bution potential £\f and changes in the value of Interfacial tension of ex traction system interface. Solutions of tributylphosphate (TBP) in ehlorbensene as an organic phase in the extraction system, and solutions of ThCl. and Feci, in 1m HC1 as aque ous phase of the system were the object of our Investigations, The faot that the values of dielectric constant of TBP and ohlorbenzene were similar was the reason of choicing just such organic phase of the extraction system. The changes in electrical distribution potential (with aid of ionization method /У) and inter faciei tension on the oil-water interface (with drop-weight method) in dependence on TBP concentration in chlorbenzene were measured. These measurements allowed us to study the mechanism of passing of thorium salts (weak passing) and ferric salts (strong passing) acroeg che oil-water interface. In separate measurements the limiting distribution coefficients of HC1 where AN' denotes distribution potentials difference ^ - y~ between the systems A and B. A* -^ « calom.electr./lm MeCl in 1m HCl//sol.of TBP in CgHgCl/air/Ag el. В» уг " ca3.om.electr./1m HCl//eol. of TBP in CgHgCl/air/Ag el. the thermodynamic distribution coefficients of Th*V and Fe111 in all the in vestigated concentrations of TBP in chlorbenzene were calculated, and their values are given in the enclosed table. Solvation energy (E ) of the investigated salt can be expressed as £JJ EB = - 2RT m s2e01 + J^, where E_ denotes hydration energy of the investigated salt. After transfor mation of the above equation we can say that the difference between hydration and solvation energies ЛВ « B^ - Eg determines the ability of the metal to pass spontaneously across the interface of the extraction system. If the va lue of Л Б is positive, the parsing of metal ions from the oil to aqueous phase across the interface is preffered, If the ДЕ value is negative the metal ion passes from the water phase to the oil phase of the extraction system. From Pigs 1 and 2 it results that the two investigated phenomena, the electrical interfaolal potential and the interfacial tension, have a very similar run. The intersection of two straight lines marks the point of eri- т ImVl .-на o-ftC/, •SOB JO •ем -r$ 20 1 •700 '^^L Чч IB I N- i • «0 1 . гсмс; tenet Ю> J ю' »ф t&?in?M " #* " & »' »" W>M^ Pig. 1. Values of eleotrio distribution on TBP concentration in chlorbenzene Pig.2. Changes of Interfacial tension of investigated extraction systems depending on TBP concentration in CgH^Cl tioal micelle oonsentratioo (OHO) of TBP In chlorbenzene. As can be seen from soth figures CMC lies between 0.2 and 0.3 m of TBP solution in chlor- Densono, I.e. above 0,3 ш IBP solution produoea mXeellar system- Table 1, Values of limiting distribution coefficient S° of HOI, difference of electric distribution potential Д У between systems containing ThCl4, FsCl, and HOI, and hydration and solvation energies differences ЛВ of these systems depending on TBP ooneenotratlon in C,H_C1 о 5 TBP, s°, дуть/н, • Д\рРе/Н, *V *h.> a/1 BC1 mV mV KJ/mol kJ/mol 3.6 0.036 50 160 6.6+2 -14.6+2 1.0 0.035 40 120 8.6+2 - 6.8+2 0.5 0.025 40 100 10,3+2 - 1.3+2 0.1 0.025 50 70 8.3+2 4.5+2 0.01 0.025 40 70 10.3+2 4.5+2 0.00 0,025 10 55 19.9+2 7.4+2 Prom the obtained values we oan see that in the investigated extraction systems thorium salts will gather in the aquecua phase in the whole range of concentration of TBP In ehlorbanzene solution. In the case of ferric ions the direotion of the passing depends on TBP concentration. In the oaee of 3,6 »: ) a,- and 0,5 a IBP ferrlo ions will gather j^ the organic phase, and for 0°1 о and smaller concentrations of TBP solution the ferric ions gather mostly la the aqueous phase of extraction systems. References 1. Karpren P.M., Randies J.B.B. // Trans. Faraday Soc. 1953. Vol. 49. P. e23. 2. Kaaienski В., Kulawik I., Kulawik J. at al. // Bull. Acad. Polon. Sci. 1967. Vol. 15. P. 249. 3. Kablwelt V., Strehlow B. // Z. Blektroohem. 1954. Vol. 53. P. 658. 4. Kaaienski в., Kulawik I., Kulswlk J. et al. // Bull. Acad. Folon. Sci. 1968. Vol. 16. P. 57. 5. Kulawik I., Kulawik J., Hlkulskl J. II ISEC'88, Hosoow, 1988. Vol. 1. P. 120. 297 DEPERMIHATION op COMPOSITION OF COHPOUJTOS TORMED IH EXTRACTION 5-41 SXSTH1 H20-HH03-DILUENI-TBP (TIAP)-BBP (DIAP)-Pu(IV) A.S.Solovkin, A.V.Looanov. Ail-Union Research Institute of Inorganic Materials, Moscow, USSR The authors have studied the influence of HHOj (agl2 mole/1), HA (rs3.2x10"*2 mole/1) ТВ? (HAP) (sl.1 mole/1) concentrations, the diluent na ture (CC1., n-decane) on Pu(IV) distribution ( 39Fu concentration In the ini tial solution Is 22 mg/1) in two-phase extraction ay stems HgO-HHOydlluent- TBP (TIAF)-HA-Pu(IV) where HA Is di-n-butyl phosphoric (DBF) or diieoamyl- phosphorio acids (DIAP), TBP and TIAP are tri-n-butyl phosphate and tril- soemylphosphate, respectively. It is found that on Pu(lV) extraction «1th HA-solutiona in n-deoane Pu(IV) interacts with HA to form a compound Insoluble or insignificantly soluble In n-decane end dilute aqueous solutions of HBO,. With a growth of the HBOj con centration in the aqueous phase the solubility of the Plutonium (IV) .HA com plex increases (the extent of Plutonium preolpltation la reduced). When TBP or TIAP are introduoed into the system insoluble oompounds are not formed. On Pu(IT) extraction with HA solutions In OBI. no prelolpitates result. ISP (TIAP) has an antagonistic effect on PutIV) extraction with DBP(DIAP). It can be seen from Table 1 that with an Increase of the W3P concentration in the organic phase the distribution coefficient (D) of Pu(IV) decreases on extraction with DBP solutions in n-decane. Table 1. Influenoe of TBP on Pu(IV) Extraction with 5.3x10~3 mole/1 Solution of DBP in n-Secane. Equilibrium concentration of HHOq in aqueous phase Is 3 mole/1, the temperature is 22+2°C TBP, vol.% D 5 50.5 10 37.2 20 24.5 30 20.9 lie data on the effect of НПО, on D of Pu(IV) in extraction with ШАР Table 2. Influenoe of HNOj on Pu(IV) Distribution la extraction with 1.5x10"3 mole/1 Solution of MAP In CCl^ The temperature is 22+2«C НПО,, s mra,, D mole/1 mole/ 1 0.24 44.3 6.6 0.4 0.57 56.7 8.8 0.1 1.1 35.0 10.6 0.004 3.1 4.5 5.6 0.6 298 It le established that Pu(IV) extraction vrith HA solutions proceeds according to the equation: Pu^Caq) + ZBOj'faq) + 2Ha KA(aqb=H+(aq) + A"(aq), (2) HA(aq)=-HA,(org), (3) 2HA(org)^= 2HA(org) + HK03(aq)^(HgA2).Hir03forgl, (Й) RA(org) + S(org)=rHA.S(org), (7) (H2A2).EH03(org) + Sforgj^rWjAjj.HBOj.S (org), (8) Where HHO.(aq) Is a nondissoolated moleoule of nitric acid /3.27, S is TBP or MAP, the thermodynamic constants have been found for the equilibrium of reactions О ) that permits a quantitative description of PutIV) distribution lit the systems studied in the HHO, concentration range in the equilibrium aqueous phase «^ 5 mole/1* The thermodynamic constant values were found taking aeoount of the acti vity coefficients for the ions and particles taking part in reactions (1) (8) tf,27. References 1. Zel'vensky H.Ya., Solovkin A.S. // Eadiokhimiya. 1980. Т. 2к. S. 642. 2. Solovkin A.S. Vysalivanle i kolichestvennoe opisanie ekstraktaiennykh ravnoveeiy* H. i Atomisdat, 19€9. THE EXTRACTIOH OP URANIUM AMD THORIUM BY THI-n-BUKLPHOSPHATE IH ГНЕ PRESENCE OP THE COMPLEXONS EDTA AMI DTPA V.V.Korolev, H.A.Afonin, V.M.Sedov, A.A.Kopyrin. Lensoviet Leningrad Technological Institute, Leningrad, USSR The employment of tbe complexons makes it possible to regulate the distri bution coefficients of uranium and thorium nitrates during tbe extraction by TBP from weak-acid mediums £]7> The distinction of the logaritfams of the sta bility constants of the actinides complexonatss is the determining factor. The distribution coefficients of uranyl and thorium nitrates were deter mined for model system, which contained by 0.025 mol/dm* each of the metals. The bensene solutions of TBP were employed as the extragent, the concentrati on of TBP ranging from 0.16? to 0.695 mol/dm*. The complexon concentrations were changed from 0 to 0.06 mol/dm , pH - from -1 to 2. The uranium (VI) concentration in water was determined by a colorimetry method using acetylacetone, which was developed in our laboratory: } ml of acetylacetone is added to the sample containing 5-25 mkg of uranylnitrate and the distilled water is added up to 50 ml. The aqueous solution of acetyl acetone of the same concentration is put Into %« comparison cell. The meas urements are carried out on 400 nm when pH is 1.8-2.?. The rare earths Ions do not prevent from the concentration of uraniiim being determined, the thori um 1опз are ma3ked easily by eouimolar quantity of ED2A after the prelimina ry determination. The general model of extraction of lanthanides by associated extractants in the ргэаепсе of complexons was taken as the basis of the mathematical mo del of the extraction system in question /£7. The dimerisation of IBP in ben zene /J7, the addition of the third TBP molecule to uranilnitrate 147, and the formation of complexes of uranil and thorium ions with nitrate ions and complexons in water phase fij were took into consideration besides the dir ect extraction reaction. References 1. &>rolev v.v. cv al.// Issledovanlya i practica extractii neorga nicheskih vesr-estv. Teslsy dokladov Vsesoyusnogo soveshanlya po prlmenenlyu extrac tii v tehnologii neorganieheskih veshestv. Apatity, 25-25 sentyabrya 1986. Apatity, 1986. a.53. 2. Kopyrin A.A. et al,// ISJ.;'88! Papers. Moscow. 1988. Vol.III. P.145-148. 5. Burtsev I.A. et al,// Ysesoyusnaya conferenciya po primeneniyu extractsi- onnyh i sorbtsionnyh metodov dlia vydeleniya i rasdeleniya aktinidov i lantanidov. Moskva. 24-26 sentiabria 1964: Tez. dokl. 11.; Hauka. 1984. 3.18. 4. Afonin 11.A., Smirnov A.V.// Ill Mezhvusovskoye sovesbaniye-seminar po extractii. Donetsk. 27-29 maya 1987. Tea. dofcl. Donetsk. 1987. 3.84. 5. Uartell Л.Е., Smith E.M.// Critical Stability Constants. Vol.1: Amino Acids. S.Y. ,-b.!Plenum Press, 1974.Vol.4.469 p.: Inorganic Complexes. N.r., J..: Plenum Press. 1979. 256 P. 300 SOKE FEATURES OP FORMATION AND DISSOLUTION OP A SERIES 5-43 OP Pu(IV) ADD Zr ALKYL- AND BUTYLALKYLPHOSPHATES IN THE SYSTEt TBP-n-DODECAHE-HITRIC ACID-WATER a. S. Markov, M. 11. Moshkov, S. A. Kokina. Khlopln Radium Institute, .Leningrad, USSR It Is of common knowledge that the main products or trl-n-butyl- phosphate (XBP) radiation-chemical decomposition - mono- and dibutyl phosphoric acids form with actlnldes and other heavy metals both soluble complex compounds and Insoluble precipitations which create dlfiloultiea in extraction processes £!/• It is also known that in the organic phase of extraction system as a result of different radiation-chemioal reactions other alkyl phosphoric acids Including alkyl radicals with more than four earboa atone are accumulated Д2.37. In this paper «e have studied the curditlons of formation and determi ned the composition of salts produoed on Interaction of a series of alkyl- and butylalkylphosphoric acids having' alkyl radical chain length from 0, to 01o with Pu (IV) and Zr in organic and aqueous phases of the system IBP - n-dodecane - nitric aoid - water. The synthesis of Pu (17} and Zr alkyl phosphate salts has been conducted, as e rule, in conditions of two-phase system, the formation of the main mass of salt precipitations occurring la the region of phase boundary* We have found that the compo sition of compounds depends on the conditions of their formation, and it is determined first of all by the HNO, concentration in aqueous and organio phase** for Pu (IV) monoalkylphospbates at НШ)~ concentration in aqueous phase 1-2.$ M the sals of PuOIAPjg.nHgO composition пате been produoed (n в 0, 1, 2; MAP - monoalkyl phosphate). When the concentration of HKO- is above 4-5 и the precipitates PuiNO ,.'2(ltAP)2 are rormed. It is found that a reversible variation of precipitate composition depending on НПО, concentration oocurs: 2.5 К ННО, рщдо,)„(щр)о.« гарццщ%.пн-о. * * * 4.> M HBO, d £ IR spectroscopy of the isolated Pu (IT) monoalkyl phosph. *es is indicative of different way of coordination of monoalkyl phosphate anion: the salts of Pu(lV)(IUP)2 type include the anion of dibasic 2 acid (IMP) '. 33>e salts of PuOT)(BO,)2(MAP)2 type oontain partially ionized group of acid anion /ЙЫАР7 with simultaneous coordination through phosphoryl oxygen atom. In the case of Zr salts only monoalkyl phosphates of ZrOttDg.nHgO type (a - 0,1) have been isolated. Acoording to IS spectroscopic data the anions of type prevail in their composition. Eownver IB. spectroscopic data evidence that in addition to the anion of dibasic acid the salts ZrWD-.nHgO include also acid anions /SHIP71"*. Die solubility of Pu (IV) and Zr monoalkyl phosphates depends on TBP concentration. Юг the salts of PU(IV)(H03)2(MAP)„ type the growth of IBP volume fraction in the organic phase leads to a sharp rise of Bolubility both in aqueous and in organic phases (Pig.). ЗЭ1 4 6 8 10 " 4 3 5~ Number of carbon atoms Dependence of Pu(IV) (Ж>,)2(ЫАР)2 solubility on the length of alkyl radical chain In the 3JIAP molecule In organic (a) and aqueous (b) рпавев of the system TBP - c-dodecane - 3 H НПО,. The composition of organic phase: 1-10СЙ TBP; 2 - 3056 TBP + 70% dodeeanes 3 - 10J6 TBP + 90S6 n-dodeoane In contrast, the solubility of the salts of PuCrvXiiO^JgCMAP)^ type decreas es. When passing from zirconium mono alky lphosphates to butyl alkylphosphates of Zr(B0,),(BAP)2 type (BAP - butyl alkyl phosphate), the effect of TBP con centration on solubility diminishes. The solubility of all salts falls with the increase of alkyl radical chain length. Data presented in this paper indicate that some features In the behaviour of different monoalkyl phosphates of Pu (IV) and Zr, in particular, the so lubility- ohange, the formation of gel-like precipitates etc. are connected first of all vith the existence of different type of alkyl phosphate anion coordination in the structure of salts. References 1. Solovkln A.S., Yladimirova II.v., Kulikov I.A. // Extraction of metal ions by mono- and di-n~butylphosphoric acids produced by hydrolysis and radio- lysis of trl-n-butyl phosphate. Ser. Inorg. Chem. VIHITI. M., 1985, vol. 12. P. 136 (in Russian). 2. Rochon A.M. // Radlochea. Radloanal. Letters. 1980. Vol. 44, N 5. P. 277- 286. 3. Beoker R. , Stetglitz Ь. // Atomkernenergie/Kerntechnik. 1985. Vol. 46, H 2. P. 76-80. 302 BCTRAOTIOH COEFFICIENTS OF Am, Cm, Cf, ЙЛ, IM AMD Eu IH THE 5-44 TETRABUTYbPYROPHOSHMTE (ТВРИ - HNO, System I. Kulaviilc, J. Kula«ik, J. Uikulalci, H.Hie«odniczanski Institute of Nuclear Physios, Огасоя, Poland The objective of tola work «as to investigate extraction properties of пев organopboephorus extractants. The compounds of interest are characterized by the presenoe of two phosphor? 1 groups in the molecule. In TBFF these groups are linked by the P-O-P bridge. Extraction coefficients of the elements of interest «ere calculated from chromatographic data, using Consden's &7 equation -fc (-k -')-—-fe 4 OJ chere Qv- cross section of the static phase, Qg- cross section of the mobil phase, assuming that (a) •here S - free volume of the column, in drops, F - peak position, in drops. The constant in Bq. (1) «as calculated for each column from the known va lues of BBa /measured under static conditions/ and from the appropriate Bf values for europium. The extraction coefficient of any other element can be calculated from Eqs Ш and (2) as D'DKuT^ (3) In Table the static extraction coefficients are compared with those calculated from the chromatographic data using Eq. (.?)• Extraction coeffi cients determined by means of static extraction agree well with those calcu lated from Eq. (?). Values of log D in the TBPP-HSO? system JfflO, Ea lb Фа Am ' Cm" Of Fm + lid 14.0 II 0.38 0.23 14.4 II 0.50 0.19 0.59" 0.77 1.28 0.23* 0.29 0.42 14-5 M 14.? 11 0.66 0.23 13.0 11 0.45 15.3 H 0.77 1.07 0.36 0.73 х st 0.77* 0.99 1.51 0.38 • 0.78 17.0 11 1-3 0.97 ш - the results obtained from static extraction. In Fig. 1 extraction coefficients of Eu, Am, Cm, Cf, ГВ and lid are pre sented as a function of the concentration of nitric acid. As expected, ex traction coefficients increase with the concentration of the acid. For the elements of study, the following sequence «as observed: 303 —•**g&mm~ Ha> "W*d>DOr> Di«. Jig. 2 illustrate» the dependence of extraction oesffleients of lanthanidas and actinldea on too atoalo number Z. Рог lanthanideB and aotlnidea /in and OB/ the relation is lintar «1th the slope 105 D/Л Z к0"12. For transourlun omenta the straight line breaks doen and the extraction coefficients of Of, Fa, and Hd lacioaae тегу little eith Z. ' « js 16 tj ia M HNOj Pig. 1. Dependence of log О on Fig. Э. Dependence of log D on the the concentration of nitrlo acid atomic number Z of rare earth and in the TBPP-HHOj system fox Bu, transuranium elemonte In the TBPP- ill, Cm, Of, Fa, and ltd syatem llendelevium «as measured by registering the products of spontane- ons flesion of its daugbter isotope. 256'Pa . The fission products «ere regis tered using the method of glass plates /27. Beferencoa 1. Conedan В., Gordon A.H., Martin i.J.P./'Biochem. J. 1944. Vol.je. P.244. 2. Psrelygin W.P., Iretiakova C.P., Zvara I. Preprint No 1325. Joint Insti tute fox Huolear Beoeaxch. Sanaa, 196?. 304 ACTINIDE COMPLEX FORMATION WITH BI- AHB TRIDEHTATE OROAWOPHOSPHORUsf 5-45 | COMPOUNDS (OB ANOMALOUS AMI STEEHGTHESIMG ЕРРБСГ) ' —I A.U.Rozen, Z.I.Nikolotova, N.A.Kartasheva, AU-unlon Research Institute of Inorganic Materials» Moscow* USSR Complex formation can be studied Ъу an ext'.aotion method alnoe the extrac tion equilibrium constant KQX is proportional to the complex formation cons tant in an organic phase В Q (i.e., the equilibrium constant of a reaction in a diluent HeA-t-qbdeAgL ). extraction? studies showed that the etrength and stability of the oomplexes of actinides with monodentate compoundo of the (ROJjJO-tROljRPO-HgSO-RORjPO.RjPO-H-Asa-R^NO saries(and correspondingly the extraction) decrease with an increase of the suhstituonts R eleotroncga- tivlty X and Increase with the extraotant basicity pK^ilgK^-A-BZJjjMi+bpK^O) where А, В, а, Ь are constants (/17, A7). Relation (1) la also fulfilled on the extraction of acids (HNOo, ВСЮ. and oth.) with bidentate compounds - diphosphlne dioxides R2P(0)CH2(0)PR2 (abbreviated 2R2R') and carbamoylphoe- phlne oxides E^P(0)CH2(0)CNR^ (abbreviated R2/RI) when complexes with a mo nodentate coordination are formed. But on actinide extraction when complexes with a bidentate coordination* six member and longer oyoles are formed (£57, £3 and A/) an anomaly was revealed. As it was expected on replacement of alkyl aubatituents (Xg-2.0) with more electronegative aryl-phenyl (Xj_»2.35), tolyl ones (I.e., on Sx growth) the compound basicity and the oxygen elect ron donor ability decrease (as evidenoed by the x-ray electron and IR-spectra, the decreased HMO- extraction) while the strength of actinide complexes (K •) is nevertheless lnoreased (by A G#£12 kJ/mole per 2Ph«goups) • The effect cal led anomalous aryl strengthening (AAS) shows up On extraction either as true AAS when In the Alk2P(0)CH2(O)PAli2-Ar7P(0)CH?(0)PAlk2-Ar2P(O)C»2(O)PAr2 se ries both the distribution coefficients <£ and the extraction constants (Am and other actinides and lanthanldas (III)) grow (Fig.1a,b,d)or as a visible effect when only the distribution coefficients grow but the extraction con stants decrease (aotlnldes (VI), (17) (Fig. 1c,d). This Is due to the fact that as oompared to actinides (113) for actinides (VI) and (IV) a stronger negative induction effect of substltuents is observed (the coefficient В In equation (1) is by a factor of 1.5 more for U(VI) and Pu(lV) than for Am)and the additional energy Д G is insufficient to compensate for it (however, due to A G a deorease of the constantв is very small-lees than by a factor of 2 per two aryl groups while on monodentate compound extraction a" 300 times decrease would be observed). In the above series the distribution coeffi cients J. f-y, J. yj grow through the suppression of the nitrio aold extraction (due to the Induction effect of electronegative aryl substltuents) and the corresponding growth of a free extraotant concentration L (remember that J. - X/HOj/3 A. On extraction with trldentate extraotants TDE-R ^» > II II • "••••A-"' 20.3aK.I607 305 when RaCB, la replaced with Hi true AAS is observed during extraction of both actinides and lanthanidefl ill) and actlnides (IV) Fa, Ир, since HNO, extrac tion (and correspondingly L) does not depend os the В nature, the observed Increase of ot also denotes the growth of К fi,57. ,„*o^flm »Mi МЯЛ « Pig. 1. Distribution coefficients vs /Wsop and Ки и J I and basicity (extraotant concentration! a-0.05 mole/1; b.c-0.01 II in dlchloroethane) Three cireunstaneas are important to understand the AAS nature. First, on replacement of aryl groups with others of the same electronegativity X, e.g., C1(CB2)2 AAS disappears, hence, it is not related to X, but to the Ar nature. Second, when aryl groups are separated from phosphorus with CHg-group inhibit ing the conjugation (tetrabenzyl dioxide) AAS disappears. This means that on closing a six member oyole with the metal the electron density is delocalized from phenyl rings la the cycle formed, which Is the oause of AAS. The third is the bridge length and structure influenos. In case of tetrsaryl dioxides an elongation of the bridge to the ethylene and propylene ones results in al most complete and full disappearance of AAS despite a growth of the ligand basicity (Pig. 2a). If the ethylene bridge is replaced with the vlnylene one CHiCH, for the els-conformation AAS la restored (Fig. 2a). It can be concluded that in the six member cycle a system of conjugated bonds results that is deatruoted by a seoond CHg-group but restored by the CH»0H group. The observ ed high nobility of methylene bridge protons (they become highly acidic) is also in favour of this assumption» The explanation of these phenomena by a change in the distance between oxygens does not work: in ease of tetrahexyl dioxides similar changes in bridges affoot extraction very weakly (uranium, Fig. 2b); the extraction maximum falling lot * *Ш.'М Fig. 2. Bridge influence on extraction «1th tetraphenyl (a - 0.01 mole/1) and tetrahexyl (Ъ - 0.05 mole/1) dioxydea The AAS effect can tie used for the extraction of aotlnldes from radioche mical process wastes up to a level require-) by the eoology. The dual effect of aryl groups proved to Ъе helpful; as donor ones on cycle formation (acti- nlde extraction) and simultaneously as electronegative ones on monodentate coordination (НПО, extraction). This doubles the effeott the eotinide distri bution coefficients grow due to both the AAS contribution to the complex strength and the НПО, extraction suppression. The use of tolyl groups makes it possible to ensure the compatibility «1th diluents (the test of 4 tol di oxide and tolg/bUg oxide see the papers by Nikiforov A.S. et al. at this con ference). References 1. Rozen А.Ц., Nikolotova Z.I. // Zhurn. neorg. khimli. 1964. T.9. S. 1725. 2. Rozen А.И. // ISEC'88. Papers. Moscow, 1988. Vol. 1. F. 62. 3. Rosen A.M., Hlkolotova Z.I., Kartaaheva N.A. // Dokl. AN SSSR. 1975. T. 222. S. 1151. 4. Idem // Radlokhlmlya. 1986. T. 28. 3. 407. 5. Idem // 1SEC-88. Papers. Moscow, 1988. Vol. IV. P. 118. 307 EFFECT OF THE REAGENTS STRUCTURE AHD THE SUBSTITUENTS ИАТГОР Г5-46 AT PHOSPHORUS ATOMS OK ACTINIDB EXTRACMOH BY BISXDIAIIHL(DIAHYL)J PHOSPHORYLMETHTCL] BENZENES H.K.Chmutova, G.V.Bodrir., M.N.bitvlna, L.A.Ivanove, M.I.Kabaehnilc. I'ernadaky Institute of Geocheiiilstry and Analytical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR Polydentatn neutral organophosphorug reagents in which the fragments of different aromatic compounds serve as the hard bridge connecting the P»0 fun ctional groups are effective and selective extractants for U(VI), Pu(IV),tri- valent transplutonium elements (TPE) and rare earth elements (REE). The effectivity and selectivity of phenylsubstituted reagents has been showa to be due to mutual location of P«0 groups in the bridge [1] • The nature of substituents at phosphorus atoms in bia [4ialkyl(diaryl)phos- phinylmethyl] bensenes has been established to influence differently the ex traction capacity and selectivity of ortho- and roeta-isomers. The extraction of HBO., TPE, REE, U(VI), Pu(IV), Ee(III) and some other elements was Investigated as a function of the acid concentration and of the nature of reagents of these structures: Ra(0)P-H2C-|j2^-CH2-P<0)R2 iS^ met» and -OHjPCOjRg -CHjP(0)R O 2 : ortho where R are phenyl(Ph), tolyl(Tol), anysol(As), mesityl(Mes), butyl (But), butoxy (BuO), phenylbutoxy(PhBuO ). The basicity of the reagents studied was determined, the extraction con stants of HHOj and Am(III) by chlorophorm solutions of reagents were calcu lated. The regular Increasing of НПО, and elements extraction was observed with the increase of the reagent basicity far ortho-lsomers. This regularity was observed only with respect to BHO-, U(VI), Pu(IV) for meta-isomers; it changed with respect to T?E and REE, and so the less basic arylaubatltuted reagents become more effective extractante the more basic alkylsubstituted ones (Fig. ). As a result the selectivity of ortho-isomers is independent from the na ture of substituents at phosphorus atoms unlike meta»iaomers. In the latter case the alkyl- and aryl-substltuted compounds have different selectivity with respect to pairs U/TPE.RES and Pu/TPB,REE. 308 i wfr-r . : . i . т .. ^-г lg[R].M Ti -i Lg[R].M pK: 5ua> Mes2 >ToL2 > Ph2 >Ph6uO >(BuO)2 O(VI), Pu(rv) and Am(III) Extraction from 3 И HHO, Solution as a Punetion of Concentration of the neta-reagentB in Chlorophorm Referenoe 1. Hyasoedov B.P, Bodrln 0.V., Cbmutova M.K., Koohetkova H.E., Medved'T.Ya., Polycarpov Yu.S., Kabachnik M.I.//Solv.Extr.Ion Ejceh.1983. Vol. 1,114.P.689. 309 EXTRACTION OP AMSRICIUH(IH) PROM PERCHLORIC ACID BY \ 5-47 DIALKY].(DIAHYL)[piALKYLCARBAMOXHIEITHYLlPHOSEHIN15 OXIDES M.N.Litvina, M.K.Chmutova, N.F.Neaterova, Vernadsky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR Dialkyl(diaril) [dialkylcarbamotlmethyll phosphine oxides (CMPO) are effec tive reagents for extraction and concentrating of TPE and R"E from nitric acid solutions. The extraction of Ara(IiI) from perchloric acid eolations by diphenyl-tdi- tolyl- and dibutil- [diethyloarbamoylmethyl] phosphine o:ides [Ph2Et2, ToljEt2 and BUpEt_] in different organic solvente was studied. The dependencies of DAmfIII) and ^HCIO on tne concentration of acid and reagent, and on the na ture of reagent ''and solvent was investigated. The distribution ratio D^ was shown to be much higher in CilPO-HClO, systems than in CMPO-hSO ones and to depend on the nature of reagent (Fig. 1). It is very high (—10 ) for arylsubstituted CMPO and lower (~10 ) for alkylsubstituted CMPO, -« -3 -a -< IglH.M Hg, Extraction of Am(III) from 4M HC10. and 3» НПО, Ъу CMPO in DCE It has been shown [1] that the substitution of alkyl-radicals by the more elektronegative aryl-radicals resulted in anomalous increasing of extraction of trivalent TP2 and RSE by alkylendiphosphine oxides unlike monodentate re- flgenta. In the present study it was shown that the anomalous effect observed ear- lijr in OMPO-HNO.systems M was greatly expressed in the CMP0-HC1O. systems. The anomalous effect doesn't occur in extraotion of HC10. by the same rea gents. Although CMPO «re nope effective extract ants than TBP and ТОГО the consumption of reagents is significant in concentrating processes of TP3 from nitric acid solutions. It was observed that the addition of small amount of HC10 to americium nitric acid solutions allowed us to enchance D... The dependency of Ara(III) extraction was investigated on the relatioehip of НЙ0- and HC10, in aqueous phase. In these mixtures the synergistic effect wasn't observed. The conditions of Am (III) extraction from HNO, with small amount of HC10. were found allowing to concentrate Am up to lOO-fold under icwer СИРО concentration than from HHO,. References 1. Rosen А.И., flikolotova Z.T., Kartasheva N.A.//Dokl. Acad. Nauk USER. 1975. voi.aaa. p.151. 2. Myaeoidov B.7., Ghmutova U.K., Kochetkova N.E., Koiro O.E., Pribylova G.A., Nestarovo N.P., Medved* T.Ya., Kabaohnii M.I.//Solv. Extr. Ion 1986. Vol.4, Ш. P.61. 310 EXTRACTION О? Am(iri) BS 01АЖ5Л,(01АЙИ)1)И1ЫЖ1/;АВВДМОПЛЕТНЯ.- 5-48 PHOSPHIHE OXIDES SOLUTIONS IN MIXED AND FLUOROCOHTAINING SOLVENTS G.A.Pribylova, M.K.Chmutova, V.A.Babain, A.Yu.Shadrin. Vernadaky Institute or Geochemistry and Analytical Chemistry, Academy of Sciences of the USSR, Moscow; Khlopln Radium Institute, Leningrad, USSR DialkylvdiarylMlslkylcarbamoylmethylphosphlne oxides (OMPO) are effective extraotante for trivalent aotlnldes and lanthanides, U(VI) and ?u(IV) from highly acidic solutions. The extraction of Am(III), Eu(III), D(VT) and Pu(IV) by oxides of diphenyldiethylaarDamoylmethylpb.ospb.ine (PhgEtg) and ditolyldl- ethylcarbemoylmethylphoaphine (TolgEtj) in various solvents from nitric acid solutions was studied. The substantial disadvantage of these extractante is a limited solubility both the extractanta and extracted metal complexes in many conventionally di luents used including aliphatic hydrocarbons using ш thechnology» Tiro methods for employment of aliphatic hydrooarbona as diluents for СИРО were tested: use of mixed diluents containing the high content of aliphatic hydrocar bons (hexane, heptanet octane, ete.) and low content of another diluent com patible with OMPO (1,2-dichloroethane (DOE), dichloroDenzene (DCB), trichlo- rooenzene (TUB), o-xylene, ets.), use of aliphatic hydrocarbon in the pre sense of tributyl phosphate (TBP) as a solvent modifier. Pig. shows that increasing the content of hexane results in third IgD, phase formation. The ocntent of he- xane dependB on the individuality of the second diluent. In the presenee of DOE, DCB, TCB can use approxima tely 70S hexane, in the presence of o-xylene-5058 hexane. Prom Fig.1 it is seen (curves ?-4) that the addi tion of TBF prevents third phase fo rmation. When TolgEt, is replaced by PhgEtg third phase forms at rather lower content of hydrocarbon. It was shown that the addition of '/„ Hexane TBF allows to use aliphatic hydrocar bons as diluents for СИРО on extrao- Pig. Dependence of S^ on hexane ting and concentrating of TBP from nl- content by 0.025M TolgEt2 in the mix- trie acid solutions. The addition of ture of hexane and BCEO,)"), nca^i,2^) IBP was notioe to result In nonadditl- TCB(3,3'). o-xylene(4,4*) in the ab- ve change In D^ (eynergistio and an- sence (I'-V) and presence of С5И TBP tagonistio effects). The value of sy- (1-4) end by 0.5M IBP (5) in the mix- nergistic effect (S) increases with ture of hexane and DCB from 3M HNO- increasing [TBP] : [CMPO] and [нНоЛ. The antagonistic effect takes place at high [СИРО] and low [HHO-] . These conditions are preferable in extraction and back-extraction processes. Kg.2. Dependence of Sgg (1) Fig>3. Dependence of D^ oa [HHO,] on (left ordinate) and [En] In org. extracting by 0.05H ToX^Btg In ОСЕ (1) and > phase (right ordinate) on [Bu] by 0.05И Tolggtg In Н-(С1 2)^-вЕ2О-(0?2>г. о. Ml IolgSt2«U5H IBP In hexane from 3* HMO,. Pig. 2. Illustrates the dependenoe of Baoroamounts of En on extracting by 0.tH Tol-Jt„ in hexane In the presence of 1.5И IBP on Initial concentration of Bu in 3H HHO,. In over ell range of En concentration in aqueous phase the third phase le not farmed» A nunber of fluorocontainlng compounds of different olasses including flu- oro-ethers, formlles and arrl-alkyl ethers ae diluents for СИРО were sugges ted as sell» She solubility of CHFO In the diluents studied ohanges over a wide range, some diluents allows to obtain the extraction mixture as solvents which are suitable in extraction ability, fare safety sad ohemieal stability for isola tion of IPE In radloohemloel theohnology. # 312 •••У "Sulla--- ACTINIDE5 Offlgr.KXKS Щ SOLVENT EXTRACTION. 1BE AMIDE TH1 OF EHACTANTS 5-49 \ C. HUSIKAS ; H. COfflMMTHKB ; H-C. CHARBONHEL , H. HUBERT Coaaissariat a 1*finergie Atoaique - IMI/DKHDCA/DCH/SHP/SCPH № n" 6 - 92265 Fontenay^aux-Воввв FRANCE 1. Introduction : The H.N-dialkylaraides (1 to 4) and the N.N'-tetraalkyl .2-alkyl 1,3-diamide propane (S)are two promising classes of extractanta which could replace advantageously the organophosphorus molecules for the separations of the actinide. The main advantages of the amides lie in their complete incinerability and the small interference of their radiolytic and h>drolytic degradation products for the pro cesses. The actinide extraction chemistry with various amides will be reviewed in thi3 paper. 2. N.H-dialfcvlamides (BBMCOR') actinides pitrato complexes 2.1. Hexavalent ions : We observed two kinds of U(VI) complexes in organic media U0a(Ko]J1(Aoide)1 and 00,(MOt))H(Araide) . The second species is favored by high aqueous HNO, concentrations and high dielectric constant of the organic phase. It has been cha- ио^но,), (и, влито*; ractererized by U-V visible spectrophotometry. The same technique allows (figure 1) the obser vation of a mixt complexe UO,(N0,1,DOBA. K^BA being the acronyme of respectively N,M-di(2- e thyl hexy 1) butyramide and N,H-di С 2-ethyl hexyUiso butyramide, 2.2. Tetravalent ions i Pu(IV) forms also neu n tral and acidic complexes Fu(HO,)k( OBA)a and Pu(NO3),Ha(D0BA) . With the more sterically hin- *™ dered DO.BA, the neutral complex-is hardly formed fig, i : U(VI) complexes into 1H and has the formula Ри(ЫОа)%(по^ВА)4 vhen the DOBA, DO.BA and 1/1 DOBA/DD.BA acidic complex is the same as the DOBA one. No into dodeean CC°^ в о.ОЗ) nixed DOBA, DO.BA complex is observed. 2.3 Trivalent and pentavalent ions : The actinide (V) and (III) ions are not ex tracted by N,N-dialylamides from acidic nitrate solutions. 3. Actinides complexes foraed by the diaaides i The extraction chemistry of the diaraides is governed by the number of CM, separating the two amides function. Hexa valent and tetravalent ions are extracted by all the diaaides when trivalent ions are only extracted by the malonamides (CRR'NCO)aCKa) and pentavalent ions are not extrac ted. UOa* forms the species "0,(110,), TBGA and ТО,(НО,),Н TBGA with N.H'-tetrabutyl- glutaramide (TBCA - ((С%Н,)аМСО),(СН,),). In the solid UOjtNO^jTBGA (figure 2) UO,* ions are linked by TBCA molecules. This solid is insoluMe in toluen, but an excess of TBGA solubilizes the complex probably by forming species like JO, (SO,) ,rBGA. (TBGA) where some TBGA are in the second coordination sphere of the complex. In both 313 UOaCNOs), 1BGA and Th(NOa), TBGA the two C«0 are linked to the metal as shown by IR spectroscopy. Actinides (III) ions are extracted by the malona- raides. With DHDOMA ((СН^Н^КСО^СН,) one obser ved Am (HOs),(im0DOHA),.(0HD0HA)a with probably two DHDOHA molecules in the second coordination sphere, 4. Conclusion s The actinide extraction che mistry of amides differ by many aspects from the organo phosphorus extractants. Two main points must be stressed out. The stronger influence of the C=0 and N substituents upon the metal ligand interaction ; because of the steric hindrance due to the rigidity of the partial П character of the amide bond. The formation of acidic complexes Fig. 2 s Chain structure in M(NO,) H [Amida)x due to the higher basicity of abides when compared with most of the organophos- UOj OIO, )a TBGA phocus extractanta (see Table 1). For the acidic complexes o£ UO, it has been observed that the order of stability is : UO^HOjJjHCTEGAl^UO^HOjJjHCDOBA)^)^,^»,)^ (Malonamide^vhen the order of basicity is TBGA > Malonamide > DOBA. Table 1 - pHy of various weak bases neutralization by HClOk into acetic anhydride- acetic acid Base and acxonyn tB% pKa Isobutyraroide (i&a) -5.45 0 K,:J.di(S.tmtyl)dodecananid«(DsBDA) -4.15 1.3 N,N' .dimethyldibutylmalonamide (DHD2DA) -2.0 3.45 N,N' .dimethyldibutylsuecinaraide (DMDBSA) -1.6 3.85 N.H'-tetrabucylgXutaramide (TBGA) -1.55 3.90 Trioctylphosphine oxide (TOFO) -2.95 2.5 Tributylphosphate (TBP) < -5.45 < 0 5. References : 1. Т.Н. Sidall III J. Phys. Chen. 64, 1863 (1960). 2. V.S. Solkolov, F.G. Teterin, N.N. Sesterkov, V.: Radiokhimiya 11, 5, 525 (1969). 3. G.M. Gasparini, G. Grossi Sep. Science and Technol. IS, 825 (1980). 4. С Husikas Inorg. Chira. Acta 140» 197 (1987). 5. C. Kusikas Sep. Sci. and Technol. 23 (12, 13) 1211 (1988). ШШП1Ш AMD OTHER ACTIHIDES BEHAVIOUR IH THE PSOOESS OP I • PHOSPHORIC ACID РГО1ЛСАТ10Н WITH EXTRAGEHT PH-1JOO I D.I.Skorovarov, V.S.U1'janov, L.I.Rusin, Z.S.Golynko, A.M.Hlrokhin, A.V.Lomonosov. All-Union Researoh Institute of Chemical Technology, MOSOOW, USSR The phosphate ores of sedimentary origin have been widely used In produc tion of fertilizers. Practically all phosphorites ores are radioactive, con taining uranium and produote of its radioactive decay, thus being sources of Irradiation. Fertilizers with low radloactivity(500-1000 Be/kg) oas be obtained only via extraction of uranium and other naturally ooeurrlng radionuclides out of phosphoric add while processing phosphorites. The moat effective means of that is the solvent extraction. Commercial uranium extraction from phosphoric add solutions by the mixtures of di2(ethylhexyl)phosphorio acid with trioctylphosphinoxlde (HDEHP+TOPO) has been well studied and used/1,3,47. Tio utilization of this mixture rocuiraa the uranium extracted to be in an hexavaleut form, at the same time its re-extraction calls for establishing conditions for reduc tion. In case of 232fh and " Th being present in the phosphoric aoid solut ions their removal by this mixture becomes problematic. The study on possible improvement of the purification process aimed at removing the natural radionuclides from the phosphoric acid oomprlsed test* int an extragent of the polyalkylphosphaeene class. FN-1200, consisting of a phosphonltrile group chain -Р-И- ajoiring to phosphorous oxygen, hydro- end alkoxyl groups fc]. The model test solution contained (g/l)t uranium 0.89; thorium 0.545; ferrum (III) 2.75' phosphoric acid 3O0.0j sulphuric aoid 50.0. The comparative evaluation of extraction efficiency for Pff-1200 and the mixture for phosphoric acid purification: KDEHP + TOTO, monoootylphenyl- phosphoric acid (MOPPA) with Т0Р0, dioctylpbenylphoaphoric acid (DOPPA) with T0F0 are presented in Table. Efficiency of phosphoric acid purification OiB 1:1; t>3 mln; t°»20+2°C Distribution coefficient (D) Extragent mol/1 uranium thorium ferrumdIT} 0.05 PN-1200 10.4 77.0 0.08 0.2 HDEHF 0.05 TQPO 2.6 0.17 0.016 0.2 MOPPA 0.05 TOPO 0.17 1.30 0.063 0.2 EOPPA 0.05 TQPO 2.70 29.30 0.051 The given results show that the efficiency of SB-1200 extragent, espe cially in regard of thorium extraction, is much greater than the efficiency of mixtures with proximate ratio B^/Dg for PH-1200 and HDEHP + TOPO. The high efficiency of thorium recovery will bring about a principal change in the distributing character of the natural radionuclides when purifying phosphoric acid. 315 The model solution with 0.1 g/1 uranium has proved a negative paired cor relation between the uranium distribution ooeffioient and the phosphoric acid concentration (mol/1) with coefficient r—0.961. The Interdependence obtained la deaorioed by the equation Dg-52-58-6.52 ФЦРОА- ^ne results have been obtained In the phosphoric acid concentrations interval 2.0*8*0 mol/1* The phosphoric aold formed In the process has temperature 70° С and re quires cooling ьв Оц for the "hot" solutions in oase of HDEHP + TOPO mix ture Is 2-3 times smaller than at 40-45°C /V. The extragent PN-1200 is less Influenced by temperature, though In the given temperatures Interval D*, Is also decreased 1*4 times» The model solution of the former composition has established a negative paired correlation between the uranium distribution coefficient and the aolution temperature in the interval -30~80°C with the coefficient r • -0.999. The relation obtained la desorlbed by the equation D„ . 9.57-O.0644t. The atudies on the efficiency of the extraction uranium and radlonuolides from phosphoric acid have shown that the extragents of polyalkylphosphasenas type have undeniable advantages over the conventional mixtures sf alkyl- слй aUylphenylphosphorio acids with tertiary phosphinoxides. References 1. Skorovarov D.I. HVdroaetallurgloal processing of uranium ores* M., Atom- lodat. 1979. P. 143. 2. Skorovarov D.I. et al. Application of organic phosphorue-nltrlgen complex forming agents in the prooese of solvent extraction for uranium and trans uranium elements. H. 1 Tsniatomlnfora, 1978. 3. Bunns P., Dumltresou ?. // Hydrometallurgy. 1986. 7ol. 16, N 2. P. 167. 4. Hurnt P. i:., Orouse B.Y. // Isd. Sag. Chen.' Prooese See. and Develop* 1974. Vol. 13, В" Э. P. 286. 316 ФЕБ MODELLING OF ACTINIDES AND IAHTHANIDEB EXTRACTION WITH А1Ш9Е5 P ^ ADD TRXBlTOCbEHOSPHATB (____— A.A.Kopyrln, I.A.Burtcev, V.M.Sedov, V.V.Proyoyev. Lenooviet Leningrad Technological Institute, Leningrad, USSR Am optimisation of extraction processes requires the thermodynamic mathe matical models of the extraction equilibria. In the case of the extraction of 'actinidee end lanthanides with alkylammonium. salts and trllmtilphosphata (SBF) a vast diversity of the intermolecular interactions in the organic sad water i&aees should be taken into account. The correct modelling of extraction equ- libria in these systems requires a special search for methods of description of organic and water phases imperfections. These methods have to Ъе theoreti cally strict, based on the minimal number of empirical parameterв and relati vely simple mathematical apparatus. For water phase it was found that Pitzer's £\J and Hikulin's /27 methods are most convenient for the calculation of the water phase components activi ty, as they make it possible to calculate the multicomponent solutions proper ties using the data obtaining for binary systems- Having analyzed the literature data for 29 binary solutions of 1-2 group me'£al nitrates as well as uranyl and thorium nitrates /V we found that Plt- zer's equation range of use could be widened up to saturation regions by tak ing Into consideration P coefficient recommended by Pitzer only for the sulfates of bivalent metals. The statistical significance of the coefficients was estimated according to Fisher's criterion. The experimental water isoactivatea in 7 ternaru systems С nitrate solu tions uranyl-thorium, uranyl-praseodymium, uranyl-lithium, uranyl-magnium, lithium-ammonium, тяgn 1 urn-ammonium, sodium-aluminium) could be described well by means of equation containing fl "% without using Pitzer triplet coeffici ents. ZdanovskJ-Hifculin* a equations determine water isoactivates in ternary sys tems with approximately the same accuracy as that of Pitzer's equations. How ever their application is limited because one has to use additional data on water activity in supersaturated binary solutions to make the calculations. While choosing a suitable theoretical model for the organic phase не have focused mainly on different versions of the theory of association equilibria which enable to: take account of (by means of association constants) the main interactions of the hydrogenbonds type or dipole interactions. We have considered 5 versions of associative equilibria theory differing in accuracy of the estimation of the associates mixture imperfection. Besides we have investigated two eemiempirical equations for the solvent activity co efficients (fe ). All the models end both aquations have been examined for 39 organic so lutions, the solvent activity data being obtained in our crioscopic and vap our pressure osmomatric (VPO) experiments or taken from literature &-&1 • Both in dilute and concentrated solutions the best results have been achieved by means of an ideal associative solution model without wHue en assumption that all association constants are the srme. 317 The equation 2 2 m ,/ In £ s * B0 • m^ + В л • m д «аз found to be the most correct in dilute solution* It oould be recommended for experimental determination ox extraction aotivity in binary solutions* Rranrfning the organic solutions of alfylamnonium salts and IBP contain ing lanthanide, uranil and thorium nitrates we have completed the literature data by our Ш-, НЩ- and VFO results and correlated compositions of metal- containing complexes. They were found to be solvated by free extractant mole cules. She values of additional constants were calculated. Pitzer'a coefficients ft- ', constants of the association ana the addition al solvatation have been used in the mathematical model of actlnid.es and lan- thanides extraction with amines and IBP. References 1. Pitzer K.S. // J. Amer. Chem. Soc. 1974. Vol.96, H 18. P.5701-5707. 2. Voprosy fizicheskoy Wiiml 1 rastvorov eleetrolytov.// L. : Khimiya, 1968. 418 P. 3. Bard J.A. et al.// Chem. Eng. Data. 1977. Vol.22, Я 4. P.337-347i Chem. Eng. Data. 1979. Vol.24, 14, P.348-354i Chem. Eng. Data. 1981. Vol.26, H 4. P.391-395» Cnem. Bug.. Data. 1962. Vol.27, H 4. P.454-462. 4. Ochkln A.V.// Ihesis Doct. Sci. Moskva. 1982. 247 -• 5,-Kraus C.A. .at al.// J. Amer. Cbem. Soc. 1954. Vol.56, IT J. P.511-516; J. Amer. Chem. Soc. 1934. Vol.56, N 10. F.2017-2020; J. Amer. Chem. Soc. 19J5. Vol.57, N 1. P.1-41 J. Amer. Chem. Soc. 1937. Vol.59. S 9. P.1699- 1703» J. Amer. Cnem. Soc. 1951- Vol.73, И 10. P.4557-45&1. E. Vdovenko V.H., Galkin G.Ia et al.// Badioknimia. 1961. Vol.?, К 4. P.448- 454. 318 SOMB ASPECTS OP AHHUCHM EXTRACTION SEPARATION ИНЯ1 | j„ | RAMOACMVE SOLUTIONS OP LAHTHAHOIDES 1—1-—I \r. Jedinakova, Z.Dvorak. Prague Institute of Chemical Technology, CSSEt The results of the systematic study of extraction systems properties enabled to formulate some general as well as specific rules governing extrac tion separations. The conclusions that have been made are Illustrated on examples of some radionuclides extraction! especially lanthanoides and ameri- cium by means of tertiary amines and quaternary ammonium salts containing benzyl radical* The general characteristics of these extraction processes have been pre sented and the effects of both phases composition on the extraction proper ties of the systems have been discussed. The theoretical basis of extracted elements interaction has been demonstrated on an example of americium extrac tion in the presence of laathanoides by the mathematical expression of the dependence of the distribution ratios of the macro- and the microcomponente on macrocomponent concentration. On the basis of distribution dependencies, an analysis of the effect of the macrocomponent (la) on the extraction of the miorooomponent (Am) by ben- zyldialtylamlnes and benzyltrialkylammonium salts has been made. Assuming the validity of Dj^ a f(oJa) and Dj « ffo^), the power function of the general expression log • В « -log P-q log о1л has been calculated, the constants have been determined for the equations applying to individual extraction systems. Their physical and chemical characteristics are discussed. The description of some specific phenomena discovered in extraction sys- teme, generalization of some characteristics and assumptions enable to pred ict the effects of the individual components of the organic end aqueous phases during the extraction separation of metal salts. In practioal application it means the possibility to choose optimum extraction systems on the basis of the strongly limited number of necessary experiments. 319 STUDIES ON AMBRICIUM(IV) EXTRACTION BY SECONDARY ALKYLAMINES PROM 5-53 MINERAL ACID SOLUTIONS ' M.S.Milyufcova, D.A.Malikov, E./.Kuzovkina. Vernadsky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR Simple and rapid method of oxidation and stabilization of araericium (IV) in mineral acid solutions, containing unsaturated heteropolycorapound K10P2W17°61 and oxidizer, suggested earlier by us [i] permitted for the first time to find conditions of americium extraction in its tetravalent state of oxidation 12 J. The principles of americium (IV) extraction by hlghmolecular weight secondary amines from mineral acid solutions containing unsaturated netегоpolycompounds of different composition have been studied* Investigati ons of the influence of the structure of hetегоpolyanionв and nature of their central atom on the extraction of americium (IVJ have shown that americium (IV) is extracted quantitatively from nitric and sulfuric acid solutions con I W 0 aad tbe 11 п taining heteropolycompounds of the 17-th member (K1Q '2 17 61^ "* member (KgSiW^O-jo) of the series. In the presence of 11-th member of the se ries phoephotungstate KnFV^.O«g americium (IV) is reduced to americium (III) during contact with a secondary amine. Logarithmic plots of distribution coef ficients for americium (IV) vs sulfuric acid concentration in case of extrac tion by ^% (w/ff) solutions of secondary amines with varying length of alfcyl chain in diluents carbon tetrachloride and dlchloroethane are shown in Pig*1. Similar plots were obtained for ameri cium (IV) extraction from nitric acid solutions. These plots have been found Wb to be linear with a slope equal to 4 in dicating that anions contributed from four molecules of mineral acids have been involved in forming of the extracted complex. Logarithmic plots of distribu to tion coefficients for americium (IV) vs concentration of potassium phoephotung state are straight lines with a slope equal to 2. Consequently americium (IV) passes into organic phase in the form of complex anionJAa(P2W^Ogi^l • Lengthening of alkyl chain in the amines from Cg Pig.1. Extraction of americium (IV) by'.distributio n coefficients of americium secondary amines from sulfuric acid (IV) (Fig.1). This may be attributed to 3 solutions containing 10~ M Ka P VTr ^ n u decr6aae of "IOift 0 2 17 6l *° solubl^-ty aeti-ne salt with lengthening of carbon chains in consequence of which change in the distribution of americium 320 forming extracted compound» Only derivatives of aliphatic alkylchloridea namely carbon tetrachloride and dichloroethane have been found to be the beat diluents. Thus stoichiometry of the extracted compound has been established. It is shown that extraction of americium (IV) proceeds based on an Ion-exchan ge mechanism.On the basis of the data obtained method of separation of ameri cium (IV) from other TPS's, REE's ала some fission products лае been worked out. Separation factors of americium (IV) and some other elements for extrac tion by 153 (W/W) didecylamine in carbon tetrachloride from 1.25 H HgSO. so lution containing 10~3 M K.QSgW^Og, are listed in the Table. Distribution Coefficients (D) and separation Factors (S) Am/I.i 2 1 г 2 1 90 1 10 гэт 249cf гззп M * Al» «с» 53Es 5*Eu Sr 370e «HU яр D гг.5 o.oo7 0.083 о.обо о.ого 0.012 о.010 г.422 о.ооб о.о}б 3 Э.1'103 2.7-Ю2 3.7-102 1.1.Ю3 1.8.103 2.2-Ю3 9.3 3-7И03 6.2-102 The у-spectra of Am(IV), Cm(III) and Of (ill) in 1.25 (I H2S04 solution con 3 taining 10"* II K1QP2W1-0g1 and J-specti^ of aqueous and organic phase after emericium (IV) extraction by 1% (ff/W) didecylamine in carbon tetrachloride are presented in Fig.2. As can be seen from Fig.2 americium (IV) passes quan titatively into the organic phase while curium and californium remain initial solution in the aqueous phase. The extraction system allows 5-10 fold concentra Cm Cm tion of amerioium (IV) over a wide region of its concentrations (10~ - 10~3 M). Quantitative reextraction Am !!— organic phase of americiURi can be carried on by 2M ,l \- aqueous phase solution of nitric acid, americium thus being isolated from the complex 11 /I» Cm Cm forming agents at this stage. "50 в(Г 250 SSO 4S0 E.KeV Pig.2. jf-spectra of initial solu tion of Am. Cm, Cf and У-spectra of aqueous and organic phase after extraction References LMilyukova M.S., Litvina М.И., Jtyasoedov B.F.//Radiokhimiya. 1985.Vol.27. P.73fi. 2.Myasoedov B.P., Milyukova M.S., Kuzovtina E.V., Malikov D.A.//DAN USSR.1985. Vol.283. P.64-0. 321 2I.3aK.I607 USE OP UNSATURATED HETEROPOMANIONS FOR ISOLATION OF TRIVALENT 5-54 TRABSPLUTONIUM AND RARE 3ARTH ELEMENTS BY EXTRACTION II.S.ltLlyukova, N.S.Vareshkina. Vernadsky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, tlosoow, USSR The problem of isolation and separation of transplutonium elements (TPE) from rare earth elements (REE) is of high priority nowadays. The use of the stable trivalent state of the TPZ is still of great interest. ?or this reason the extraction behaviour of the TPE by some high molecular primary amines has been studied from solutiona of mineral acids in the presence of heteropoly- anions. Some data concerning this question have been reported previously (l,3 . Prisiaiy amines have been shown to extract TFE and REfi from solutions uf nit ric and hydrochloric acids containing heteropolyanions (see Fig.1 a,b). In ail cases extraction of TPE by primary amines is bet Lev than that of tl3E. .a a 0 Ив. Effect of mine ?*. 4^V ral acid concentration •»L^ and composition of 11- « 3+ та gand on Am (1,3,5) s* and Bu t2,4,6) extra i- JV 4 ction «-* 1.8-K10P2W17061 «f V^J 3,4-K8siwno33 as 15 г L5 05 <.S w s.e-^Pw^Ojg JHNOj"] ,H 3 31>'" [» Ф Distribution coefficients versus ionic radii of the ТРИ and Rii.v has been stu died. Distribution coefficients (D) of the TPK are constant and independent of ionic radii for extraction from НПО-, but they are not constant for extraction from HC1., De ^ being lower than Damer>iclum no matter what ia the concentra tion of UC1. Dependence of э on the ionic radii of KSE is non-linear both in H!X)-a and HC1 solutions. According to their extraction behaviour ЗЁЫ can be put into two groups: cerium groi^p. and europium group. Distribution coeffici ent з of both ?PE and RiilS have been found to increase with increasing concen tration of potassium phosphotungatate in initial aqueous solutions. The de pendence of lg D vs» lg Ki(vp2'l'l706l is described by a linear equation vn+v the slope of ?. (extraction from nitric acid) or 1 (extraction from hydrochlo ric acid). These indicate that trivalent TPK and RES are extracted as complex aniong MeCPgVZ-yOg-) I'" or Ш{?ЛК~0г^) ^- from nitric acid or hydrochloric acid, respectively* extraction of TPE and 11BE is strongly affected by the nature of an organic solvent. Chloroform has been found to be the best one. Effect of the length of the alkyl chain of a prinnry amine (Cy-C,g) on ex traction of the elements has been studied. Distribution coefficients a2 TFB and П13И are nearly constant when using amines with С«-С12 chains and nitric acid, but they decrease gi-adually when using hydrochloric acid. The decrease in distribution coefficients appears to depend an both the decrease in solu bility of primary amines and on the nature of extracted species. The etox- chiometry of extraction of Me,(III) he.s been studied and compositions of ex- 322 tracted species have been determined* Effectiveness and aeleotivity of ex traction of the TPE and REE have been found to depend on the structure add composition of a heteropolyanion (aee Fig,1 a,b). Distribution coefficients of the TPE decrease in such an order; K8siw11039>K10P2W17O61>K7Pff11°39 (1* Ш<У K8siw, ,o39^ K,0P2W,7O51 >K7P»„O39 cm HOI) The data obtained allotted ua to devalope an extraction procedure for se - paration and purification of TEE from other actinldea, rare earth elements and some fission produote (see Scheme)* Extraction of trivalent TPE from BC1 solutiona containing ЮтРЯ_Одо шакеа it possible to separate TPE and REE (see Fig», curves 5,6 )• For example, separation factors Sjmn„ of americium from europium are equal 68 and 37 whan extracting from 0.75 M and 1И HOI, respectively. The system under consideration makes it possible to separate REE toofll Scheme for separation ТЕБ EXTRACTION 0.5 -1M HNQjflq,10'3M HPS,3%AAinCHq aqueous phase. organic phase Sr,Cr,Cb,Np(v),U(Vi) TPE,Zr.Nb.Fe,Pu(lV) REEXTRACTION 5 MHO. aqueous phase orqamc pnase. TRE ZrTNb.Fe.PudvXHPC References 1. Uilyukova К .a.., Tarezhklna U.S., Myaaoedov B.P.//J.Radloanal. Chem.,Letters. 1986. Vol.1U5. P.249. 2. Milyukova U.S., Varezhkina U.S., Ilyasoedov B.P. //J.Radioanal. Chem., Articles. 1988. Vol.121. P.403. 323 AGGRESATIOH AND DISSOCIATION OF THE THORIUM, URAHIUM(VI) AND 5-55*1 RASE EARTH ELEMEHTS COMPOUNDS WITH TRI-N-OCTYLAUaLAMMOKlHM >-— ' SALTS IN ORGANIC SOLVENTS S.O.Popov, V.V.Bagreev, Veraadsky Institute of Geochemistry and Analytical Chemistry of the USSR Academy of Sciences, Moscow, USSR Thorium, uranlum(VI) ana rare earth elements compounds with trlcotylmethyl (ТОМА), trioctylpropyl (ТОРА) and tetraoctylammonium (TeOA< chlorides and nitrates i.jre investigated Ъу теапв of measurements of conductivity and cryo- scopic observations. The dissociation and aggregation conata. -a for various species in benzene end nitrobenzene were calculated with the help of tha Fuoas-Oasager theory /l/"i the generalized theory of associative equilibriums №TAE) £2/ and the aggregation and dissociation common model (ADOi) /J/, in accordance rith assumption /5/, the Fuoss-Onsager equations were reduced within the frame» ork of the ADOM to the form of 1/2 3/2 2 a-Ao-s(e(oa1) ^E(otoe1)log(c 1 2 ,/a logCfJ - -A(olOa1) '' /(1+aB(otOa,) ), where Ъ is the equivalent conductivity of solution and Л is It at infinite dilution, Ca la the extractant concentration and С ^ is the concentration of the monomerlc alkylammonium species present in the solution, e< and Kd are the dissociation degrae and the dissociation constant of the dissolved compound, a is the Intereionic distanoe parameter in an Ion pair, f is the mean ionic activity coefficient, and s, E, J , J2, A and в are numerical coefficients. In their turn, the equations of GTAE model were transformed for ADCM aims by the substitutions' H4,-Ma-^Ma1 Ms » HB + (Ra + Oo Us, Ha and Ma1 are the concentrations of the diluent, alkylammonium salt and its monomers, respectively, in molality units, and Я is the ratio of the molar volumes of the dissolved compound and the solvent. Concentration of the monomeric molecules of the aU&lammonium salt in solution (c ,) can be cal culated from equation 2 1/a o,-ca1 . The data obtained are listed In Table. Comparison of the f> and KQ values given in the Table has shown ADOM to produoe higher values of aggregation and dissociation constants. As a result of calculations it was established that dissociation constants of triootylalkylammonium compounds with the same anion increase with increas ing length of the п-elVyl radical in the extrectant molecule, and aggregation constants decrease in the same direction. It has also been found that dis sociation constants of simple and metal-cortaining compounds differ between one another la chloride systems to a higher extent than in nitrate systems. 324 Aggregation and dissociation constante for alkylammonium oompounds in benzene and nitrobenzene calculated with the help of ADCM» GTAE and PUOBS-Oneager model (PO) Benzeae Nitrohenzene Anion Cation GTAE ADCM PO ADCM Kd 10> K 10* P> I* d к„ w* J> ТОМА 27 37 5.9 1.2 3.2 1.8 ТОМА Er(No3) Ji 39 42 70 3.2 9.4 3.6 ТОМА ll. (ш3>§~ 87 119 0.99 0.11 0.63 5.2 том 002(N03)|~ 73 77 51 2.0 5.0 4.7 ТОМА 01" 21 26 0.049 0.25 0.03 0.69 ТОМА stoif- 30 36 104 10.2 9.9 2.2. ТОНА ThCl|" 66 93 81 1.1 4.4 5.0 ТОНА uo2ci|" 53 58 59 2.8 6.3 4.1 ТОРА MOJ 17 -- 1.5 -- ТОРА Th References 1. Kopyrin A. A., Proyayev V.V., Konarov E. V., Burtzev 1. A. // Z. Pays. Chim. 15-4. Vol. 58. P. 386. 2. Marcuo Y., Kertes A.S. Ion Exchange and Solvent Extraction of Metal Cora- pounds. London: Wiley-Intereclence, 1969. 3. Bagreev V. V., Zolotov Yu.A., Fischer C., Kaidivarenko L.M. , Popov S.O. // ISEO'88! Papers, Moscow. 1988. Vol. 1. P. 87. 325 Инн ииАькямвгеишмоипш CARBONATE I S.I.Stepanov, M.B.Bolotin, A.H.Chekmarev. Mendeleev Institute or Chemical Technology, IIOBCOW, USSR Quaternery ammonium salts (QAS) and In particular trlallsylir.etylammonium carbonate (TAMAC) are effeotlve extraotans of uranium(YX) from alkaline and carbonate solutions. There are a lot of different publications in literature abou*- the composition of uranium compounds extracted from carbonate solutions by QAS. They can be extracted from hydrolyzed eompouns (И.Ю2п+т_2Ш2(С0,)в (OH) [1} , to the polynuclear ones of the follwing type (R.NJ-D^^^, iw2-6 [2] , where R,H - is a quaternary ammonium cation. The extraction of tricarbonatouranilate complex Is well known and its field of extraction can be properly defined [3j . The results of systematic etudes in the field of solvent extraction che mistry of uranium carbonate compounds with TAVAC in wide range of CO?" - HCO~ ions and metal concentration variations in Kater solution, are presented in this paper. We used solutions of TAHAfi (the length of alkyl substltuent equals 7-9 carbon atoms) in toluen as an extractant. The initial water solu tions were prepared on the basis of natrium or kalium tricarbonatouranilate. The correction of water solutions pH was made with COg or HCL. For determi nation of extracted compounds composition were applied different investiga tion methods, including the spectrophotometry method of absorbing complexes number determination in water and organic solutions, interfacial distribu tion, loading of organic phase, potentiometrical titration of extracts, IR- spectroscopy, polarography and ofaemical analysis of phases. The solvent extraction of uranium(YI) from oarbonate solution in the range of pH 7.0 - 12.5 was Investigated In detail. It was found, that under pH>9-0 in the presence of small excess of carbonate anions In water solutions tri carbonatouranilate anion is extracted exclusively, forming (E.K).UOjCOO,), compound in organic phase. It was interesting to study the pH interval 7.0 - 9,0 for carbonate solution, since in this Interval the extraction of dicarbo- natouranilate or polynuclear carbonate complexes of uranium oould take place. The above investigation methods together with analysis of initial water solutions for the determination of absorbing complexes number and with refe rence data about its composition under conditions of extraction by ТДМАС showed, that main extracted forms are tricarbonatouranilate, dicarbonatoura- nilate and polynuclear carbonate complex, with supposed composition (UO ) (C0,)g . The method of initial water solution pH correction with C02 or HCb does sot Influence the composition of the extraoted complexes. It was find, that the ratio between concentrations of extracting tricarbonatourani late and dicarhonatouranllate depend on the solution pH (with pH Increase the share of extraoted tricarbonatouranilate anions Increases as well), metal concentration, phase ratio (0:W) and extractant concentration. Complex with the higher stability constant in water solution is preferably extracted Into the organic phase under other equal conditions, folynuclear carbonate uranium coplez with the supposed composition (иог),(СО,);?", is extraoted mainly near pH 7.0 and In small quantity. At higher pH this complex can not be deter- Э26 mined in initial water solution and in the corresponding extract. The sum mary data about uranium(YI) extracted compounds composition for carbonate solutions in the range 7.0 - 12.5 (Т411ЛС ae extractant) are given in the Table. Composition of Carbonate Solutions and Uranium(VI) Extracted Complexes (TAMAC as extractant) •1 Composition of Number of 0:» Number of Extracted complex trailer Bolutlon particular extracted composition in water particular solution -3 1. Cu=2.36-10 m/1 1 1:1 1 (R4N)4U02(C03)3 pH 12.5 3 2. Cu=4.83-10" m/1 2 1:2 1 (R4M)4U02C003)3 pH 9.9-7.e 1:5 1 Са4н)2ио2(оо3)2 pH var C02 3 3. 0u-6.34'10~ m/l (н4н)4ио2(со3)3 pH. 10.0-7.0 2 1:7 2 (E H) U0 (C0 ) pH var HCL 4 2 2 3 2 2 4. Cu=2.23'10" - (Е4Ю4ио2(со3)3 0.428.10_2m/l 3 1:2 3 co2 (Е4Н)6(П02)3(003)6 2 0U=2.88.10" - 1:6 5. 3 3 (й4н)4ио2(оо3)3 0.29'10"2m/l (в4Югио2(оо3)2 pH 7.0 HCL (Е4Ю6(П02)э(003)6 Data in the Table show, that only complexes wich are present in initial water solution are extracted by TAMAC. Uranium carbonate complexes with the lower stability constant can be found in organic phase only in case of their concentrating with the phase ratio increase. Extraction equilibrium constants were calculated for (R.K) U02(00,)3 - (1) and (E4N)2U02(C0,)2 - (2) compounds using partition data in the system with TAMAC. This constants were calculated taking into account the hydration of organic phase components. They were: ^=1.47.10 and Kg=1.48-10 accodingly. References 1. Polomino V., Sedano C.J.A. et al// An. gaim.realsoc. esp., fia. у gaim. 1970. Vol.66, H 11. P.901-910. 2. Suxian L., Xianghao lu. He huaxue yu fangshe huaxue. 1984. Vol.6,111. F.3. 3. Phedotov O.H., Stepanov S.I. et al. Irudi MChTI. 1982, Vol.125. P.30-33. 327 PREDICTIONS OP THE MUTUAL 1НШ1ЕНСБ OP THORIUM, URAHim(VI) AMD 5-57 IAMTHAHIDES IN 3XTRACTI0N SYSTEMS WITH TRlOCTlLALlCtLAMMOinUM SALTS v.V.Bagreev, S.O.Popov, Xu.A.Zolotov, Vernadsky Institute of Geoche mistry and Analytical Chemistry of the USSR Academy of Sciences, Moscow, USSR The salts of quaternary ammonium bases (QAB) are efficient extractante for actlnides and lanthanides. It la very important to know now the extraction of one of the metals affects the recovery of another one. In those cases when one of the extracted netals is present in solution In a much higher concentration (macroelement) than another one (microelement) their mutual influence often results in the suppression of the microelement extraction. Generally, the character of the Influence of all factors on the behaviour of the microelement in the presence of the macroelement during the extraction can be analysed Ъу application of the following equation s ^ М^^МП^ЛР/Г! *»(1-/il.i.ti''([Vl74''3i»'' S D 1 % [R4HB]2 I(1-Лов1>,)(ик^яЧ-Чк (,. дса1# t)-i([н^+р-рI" where S is the extent of extraction suppression! D, and Dg are the distribut ion coefficients of the metal investigated in the presence and in absence of the macroelement in the organic phase, respectively, п.. and n are the stoi- ihiometry coefficients for micro and maoroelement extraction, С , is the concentration of the alkylaamonium species present in the solution, C& is the analytical concentration of the alkylammonlum salt, [RjHBj is the concentrat ion of the free extraotant in the organic phase, ("Йд"^l e *be concentration of the alfcylamnonium cations, Cm and Cm, are the concentrations of the micro and macroelement in the organio phase, ^and К are the aggregation and dis sociation constants, respectively, of the extractant, K_ and K_, are the dis sociation constants of the metal-containing compound of micro and macroele , 1 K R HI + ments. In above mentioned equation the value Гн4Н' ']" + [В"3 • ( aT 4 0 + 2 + + + [S4N ] )/(Ka[R+Jffijj"R4M J), and [я4Н ] can he calculated from equation + [R4N ] . (K.. 0..+ КЛ - n2 \W* The value of 0al in main equation was determined from the following relation ship! °a1 A 2(0a - V> "c a1(1+a fi °„ - >fi°m^ + °a -2 V • ° We used these equations to predict the extent of extraction suppression of lanthanides in the presence of urenlum(vT) and thorium. Some results of calculating axe shown in Table. A satisfactory correspondence between the theoretical and the experimental S values is seen to have been obtained. The presented model thue makes possible a quantitative description of the simultaneous extraction of traces in the presence of uranium and thorium by using solutions of such aggregated extractante as QAB nitrates and chlorides. 328 Theoretical calculation of the degree of erbium extreation suppression in the presence of thorium and uranlim(Vl) In the simultaneous extrac tion of metals «1th 0.2 M trioctylmethylammonium chloride end nitrate solutions in benaene f 3 c tt P It Ь»в ЕГ ». °a1' * calculation experiment ТЬог.'лия nltrat« 0 0.00344 0.0187 0 0 0.01 0.00327 0.0179 0.13 0.14 0.05 0.0253 0.0I32 0.81 0.82 Uranyl nitrate 0 0.003*4 0.0187 0 0 0.01 0.00390 0.0179 0.14 0.14 0.05 0.00543 0.0135 0.83 0.84 Thorium ohlortd! 0 0.00029 0.0249 0 0 o.oi 0.00248 0.02Э9 0.63 0.69 0.05 0.00598 0.0178 1.37 1.40 Ur&nyl ohlorj.de 0 0.00029 0.0249 0 0 0.01 0.00217 0.0239 0.61 0.69 0.05 0.00515 0.0178 1.37 1.44 329 ON THE GROUT I^ARATION OF TRANSPLUTONIUM AND HARE-EARTH ELEMENTS __„ I Hf DI-(2-BIHnBKS3rL)rHOSPHORIO ACID, CONTAINED COHPLEXING AGENT I 1 I.K.Shveteov, P.S.Trukhlyaev, V.A.Kalistratov, ».M.Dyatlova, N.V.Tsyryulnikova« Zil.Taareva. Kurchatov Institute of Atonic Energy. All-Unlon Research Institute of Reagents and Specifically Pure Substances» Hosoow, USSR The purpose of the present paper is the search for such extraction sys tems of the group separation of transplutonium (TPE) and rare-earth elements (RKB) in which a oomplexlng reagent is introduced not into an aqueous phase» as it ia performed tradltionBllyt but directly into an organic phase (sol vent). The extraction and extraotion-chromatoaraphic separation of some TPE and RBE is studied in the paper by means of di-2-ethylhexylphosphoric acid (D2EHPA) containing a pentaoctyl ether of diethylenetriamlnpentaaeetio aoid (POMPA) and a dioctyl ether of lalnodiaoetic acid (DOJDA) as additional conple- xlng reagents. PODTPA was synthesized by etherification of corresponding conplexons by an oetyl alcohol in the presence of thionyl chloride by the Brenner method. DOIDA пае purified by passing a benzol solution through a column with AljO-j and Identified by element analysis data end melting temperature of its picrate /V- Trivalent amerlcium, curium! berkelium, californium, cerium, promsthium, europiuml thuliun, were used as TPE and RES spacimeas. The set of distribution and separation coefficient в of eight TPE and SEE specimens makes it possible to select oonditlons for extraction separation of these elements. Separation factors of various element pairs in certain extrac tion systems lie within the limits of 1.0-90.0. She extraction systems with the complexing reagent introduced into extra- gent (D2BHPA) are distinguished adcantageously from extraction systems with complexon in an aqueous phase by following factors' a) TPB and REE extraction can be accomplished from real technological so lutions without change in their volume and salt composition; b) lack of additional operations such as a release of the aqueous phase from oomplexons (in TAlSPIK-prooeas) or from salting-out agents (in TRAJIEKS- prooess); c) ТРЕ and REE separation can be performed in a more acidic region of aqu eous solutions (0.1-1.0 II KNOj) as compared with the known extraction pro cesses (pH«2-3). Reference 1. Dyatlova N.M., Temklna V,Ya., Isareva Z.I., Yaroshenko G.F. // Trudy IREA, 1976. N 88. S.18-24. 330 ЕИНА0Т10» О* САЫРОЮШШ(ГИ) PROM AQUEOUS PYROPHOSPHATE I AND TPIPObYFHOSPHATB SOMJTIOMS I V.Chakravortty. Department of Chemistry, Utkal University, Vanx Vihar» Bhubaneswar, India S.A.Ferevalov, Yu.M,Kulyako, Vernadsky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the U3L?K, Moscow, USSR Although higher oxidation states of californium are rather unstable^/, californium(III) was chemically oxidized, stabilizing califomium(IV) in pbosphotungstate solutions^/ and, el ec trochaic ally oxidized^3,47 in carbonate solutions. While attempting at oacL.dr.tian of californium(in) from pyrophosphate and tripolyphosphate solutions the problem of its extraction from such media was encountered for its regeneration from various redox experiments due to the limited availability of californium-24-9. Monographs ^1,57 having review articles relating to extraction chemistry of califor nium show that there has been no study on the extraction of this transpl- utonium element(TPE) .from such media. In view of the above and in order to know the nature of the extracted species, studies on extraction of Cf^**- from aqueous solutions of these complexants by di(-2-ethylhexyl)phoaphoric Bcid(HDEHEA) have been, undertaken. A comparison of liquid-liquid extraction behaviour of calirornium(lll) rrom aqueous pyrophosphate and tripolyphosphate solutions(0.1 M) by HDBEPACl.O M) in n-heptane as a function of the equilibrium pH in the range 0*5 shows that extraction from tripolyphosphate media is less than that from pyrophosphate solutions at any aqueous acidity. Again,extraction from pyro phosphate media is almost quantitative in the equilibrium pH range 4-5. However,for extraction from tripolyphosphate solutions two to three conse cutive extractions in the equil.pH range 3-5 can only isolate Cf^* complet ely. The equil.pH value has been found to be lower than the pH value befo re extraction for pH^ 2. The slopes of the linear log D vs. pE plot (D is the distribution ratio) in the equil.pH range 0-2 are I.? +, 0.06 and 2.0 *_ 0,2 for extraction from pyrophosphate and tripolyphosphate media,respecti- velyj The slopes of the linear plots of log D vs.log HDEHPA are 0.7 + 0.0? and 1.65 ± 0.2 for pyrophosphate and tripolyphosphate solutions,respective ly concentration of НШША was varied from 10 to 0.2 M and at constant equilibrium pH в of aqueous phase). From various considerations, the follo wing extraction mechanism has been proposed: 5 (i) extraction of Cf by HDEHPA( represented as (HA)2, a dimer) «&,.) • » <»>a («».> - C£A3-5 ^Ors.) "'н(вс.); (I> (ii) complex formation of Cf'+ with pyrophosphate/tripolyphosphate (the corresponding acid is H_L,a polybasic acid) + B 2 «ft».) *V(4.) - «Vi^T' <*""> (iii) extraction of the complexes by HDEHPA 331 CfHL(5~n*m) + (3-n+m) (НА), , , CfHL.A,, „ ..(З-ш-т)НА 2 ^ Cf (H-PgOr,)* + (HA), - Cf(H2P20-)A.HA ч- Н+ (5) ' 2+ + Cf(H.P,0T») + 2 (HA), - Cf(KaP,0T.0A,.2HA + 2 H Э 10 2 * (aq.) (org.) * 3 Ю 2 (org) (a(j). (6) Backextraction experiments show that even I II HgSO^ solution can reextr- act Cf^+ while two to three consecutive reextractione with 5 M HNO, solut ions can only isolate californium(III). Quantitative extractions from pyro phosphate solutions Dufferred at pB 4.0 and 3-56. and quantitative reextra ctione with 2 M HgSO^ solution were achieved. Thus, this IPS can be extra cted from pyrophosphate solution in the presence of various oxidants such 9S XeOg- , S,0g ,etc, under identical conditions. Reversed phase partition chromatography experiments(the column for which waa prepared by impregnating porous Teflon with HDEltPA) were performed to recover 300 «g of californium- 249 from various redox experiments. References 1. Katz J.J.,Seaborg 6.Т.,Moras L.R./eds./ The Chemistry of the Actinide Elements.Chapman & Hall,1936. 2. Ityasoedov Б.Р. in Actinidee in Perspective/ed. Edelstein B.li. Hew York: Pergamon,I982 (references cited therein). 3. Irenkel V.Ya.Kulyako Tu.ll. ,ChiBtyakov V.ll. .Lebedev I.A. ,Hyasoedov B.F., Timofeev G.A.,Erin E.A.// J.Badioanal.Hucl.Chem.Lett.I9B6.Vol.ICW.P. 191- «. Vyaaoedov B.F. .bebedev I.A.,Khiznyak F.L.,TiDDfeev G.A.,£renkel V.Ta// J.Less. Common Metals.I9S6.Vol.122.P.189. 5. Navratil J.D.,Schulz W.W./eds./ Actinide Separations/Acs Symp.Ser.I17/; Transplutonium Elements-Production and Recovery/ACS Symp.Ser.I6I/. Washington D.c.:American Chemical Society, I960 & 1981. 332 COORDINATION PEATURES OP TETRAVALENT BERKEblUM AMD METHODS OP ПВГ j_6o RECOVERY AND PURIFICATION V.N.Kosyakov, N.G.Yakovlev. Kurohetov Institute of Atomic Energy, Moscow, USSR The detail analyses of the date, on the complex formation of actinides and some other elements in tetravalent state shoves, that the coordination properties of tetravalent berkeliuxi should be sufficiently different from that of other tetravalent actinidee and cerium, due to its small ionic ra dius. The most significant difference can be expected in the interaction of the tetravalent cations with weak complex-formating Uganda, such as nitra te-ions, which form mainly outersphere complexes. This conclusion is comple tely confirmed by the results of potentiometrlc studies carried out with both berkelium and cerium in a wide range of nitric acid concentrations/I/ (Fig.1), as well as by electromigratlon experiments with Bk(IV), Pu(IV), Th(IV) and Ce(IV) in nitele acid solutions /27, (Fig.2). 1.7 «Г 15 . « Ч Ю . Я»- *» • 5 VTBktlV) S"b -5 . T-ftl(IV) й -,0 • Ce(IV)^ 1.4 ' • ' | ' • • ' | ' ' • ' | I I I I | l 1 1 I 1 ' 10 °HHOj,M ,M тлю.3 le.J. Formal Potentials of Bk(IV)-Bk(III), Ce(lV)-Oe(III) in nitric acisid sosolutioni s Pi£.S. Electromigration of Bk(IV), Oe(lV), Fu(IV), Th(IV) in HNOj The observed difference between Pk(IV) and other Me(IV) in their inter action with nitrate-ions must be displaied in the solvent extraction beha vior of these cations from nitrate solutions. Systematic researches of Bk(IV) solvent extraction by neutral (TBF, TOPO) and acidic (HBEHJ) phos- phororganic extractants from nitric acid solutions have been carried out. The regularities end mechanism of the Bk(IV) extraction by these solvents have been determined. Some common and different characteristics is Bk(IV) lolvent extraction behaviour in comparison with the other tetravalent acti- nide, Ce(IV) and Zr{IV) have been established. The moat significant diffe rence in the solvent extraction of Bk(lV) and other tetravalent cations is appeared in concentrated nitric acid solutions. It la well seen from the Pig.3, where the extraction of Bk(IV), Pu(IV) and Ce(IV) by 0.002 II HDEHP is shown as example. Similar picture is observed in the extraction by IBP and TOPO. With the Increasing of HNO, concentration the distribution ooef- 333 Fig.3. Bk(IV), Oe(IV) ana Pu(IW extraction by 0.002 M KDEHF (decane) 2- ^^^ ^ Q Q from HNO- solutions CWr"^ Bk(IT) 1 - fioients of Ce(IV) and Put IV) pass through the maxima and sharply decre lg S ase In all eases, while theBk(IV) о- ^EL-I*"^ distribution coefficient increases continuously. It results In a situa -1 . \ tion, when, for example, in a system ae(iv) >L. of IS M НПО,- 0.002 11 HDEHP the sepa -2- ration factor between Bk(IV) and '•'•{''•-•)•' ^]Q Ce(IV) is'higher than 21Ю3 and the 10 15 efficient separation of these two ele "НПО,* ments become possible directly at the extraction stage. High degree of berkellum purification from trivalent TPE and REE is achieved at the same time. The results obtained allowed to develope -some new extraction-chromatog- raphy techniques for recovery of * Bk from irradiated targets, providing a high degree of purification from the other actinidee and lantanides inc luding cerium for one cycle. The technique with HDEHP Д7 we usually apply 249 'in recovery of ^?Bk from irradiated targets and in analytical determinati on of herkelium. TBP Д7 is mainly used in large scale treatments of irra diates targets in a combination with HDEHP, The technique with TOPO /57 is * ' 249 249 usually applied for the purification of "Cf froa the traces of "Bk. References Kosyakov V.N. et al.//Bsdiokhimiya. 1977. T.19. 1. Slmakin О.Л. S.366-372. , Fridkin A.M. et al.//J.Radioanel.Chem. 1979. Vol.53. 2. Makarova T.P P.17-24. , Yakovleir N.O. et el.// Radiokhimiye, 1977. T.T9. 3. Kosyakov V.S, S.486-492. Yakovlev N.G., K&zakova G, //J.Radioanal Chem. 1982. 4. Vol.75Kosyako,v H V.N1-2, . P. 113-120. Kosyskov V.N., Yakovlev N.G.//Hadlokhimiya. 1983 T.25. .183-137. 334 THE INFLUENCE OF RARE EARIB MBMBNTS ON EXTRACTION О? АСТВШЛ1 i 5-61 WITH DI-(2-BTHYiaBXSL) PHOSPHORIC ACID FROM INORGANIC ACID SOLUTIONIS Z.Szeglowski, B.Kuoloa. Institute of Nuoloar Physios, Craoow, Poland Investigations of actinium liquid-liquid extraction by di-<2-ethyIhexyl) phosphoric gold (BDSSF) are relatively rare /л-3- They show that the extrac tion of actlniuia oonsiderably'depends on the physicochemical processes occurr ing in the extraction system. This paper describes soae studies on the extraction of actlnium-228 with a BDEHP solution in n-heptane from aqueous solutions of nitric, hydrochloric and sulphuric acids. Ibis research was performed under the conditions of high purity of the extraction system in order to avoid the presence1-of trace motala whloh are subject to bydrolyeia. In a previous равег /37 it was found that the presence of micxoquantities of some metals in the extraction systems changed the extraction of actinium to a considerable extent. Pure HDKBJ (93.6*) was employed. All other chemicals were of analytical reagent grade. Extraction of actinium was performed ae a function of the mineral acids and some HBB concentrations in aqueous solutions (see Tigs. 1 and 2). In Pig.1 is presented actinium extraction by 0.1Ы BDBBP in n-heptane f 0 \ 10 - V 4 '^ 5 \A 0.1 6^"% 001 \ • \ , . . , \ m <" [NNOj*1 •> [HCl].H Pig.1.The Influence of la(H0,), Fig.2.nie influence of 0.025* in various concentrations on actini LaClj (1), HaCl3 (2) and SmClj (3) um extraction from HMO, solutions: on extraction of aotlnium fron 1.-without La(N03)3, 2.-О.0О2, 3.- HC1 solutions. 0.1И HDKHP 0.005, 4.-0,010, 5.-0.025, 6.- 0.050H La(N0j)3. 0.1U HDEHP as a function of HHO, and La(N0,), concentration in the aqueous phase. The extraction ooeffiolant of Ac in the absence of lanthanum decreased linearly with nitric acid concentration with slope -3 in the whole range of its concentration. In the presence of lanthanum at a low acid concentration «0.111) the extraction coefficient values for actinium decreased with smaller slope than without the presence of La. As oaa be seen in fig.1, this slope decreased with Ia(H0,)~ concentration. 335 At a high acid concentration ( }0.111) the D-valuoa for Ac decreased «1th slope -3 Independent of la(NO-) concentration* In the case of actinium extraction from hydrochlorio, perohlorio and eulphuric acid solutions a similar result was observed. Pig. 2 illustrates the influence of lanthanum, neodynlum and samarium on the extraction of actinium from hydrochloric add solutions* All the rare earth elenents changed the extraotion of actinium from acid solutions in the sane way. The results of the present experiments indicate that the rare earth elements in diluted acid solutions was subjeot to hydrolysis and formed aicrocolloidal hydroxides* Hie products of hydrolysis sorted actinium on their surface and thus changed actinium extraction* Above the 0*111 concentra tion of acids the hydrolysis of rare earth elements did not occur and the extraction of actinium proceeded normally. Bbattaoharyya and Ganguly observed a similar dependence for neodymivni and terbium extraction by HDBB? from nitric acid solutions /17» Aotlnium In diluted acid solutions does not precipitate as an actinium hydroxide beoause it is dissolved in water much better than the hydroxides of RUB. References 1. D.P.Peppard, S.C.Haaon. W.J.Sriscoll. R.J.Slronen^J. Inorg. Duel. Chem. 1958. Vol. 7. P. 273* 2. Z.K.Karalova, L.K.Bodionova, Z.I.Pyzhova, B.P.Hyasoedov//Radioldiliii. 1978. Vol. 20* P. 42. 3* Z.SBff^owski, B.Kuoica, Institute of Nuclear Physics, Cracow, Report Ho. 142'9/C 1988. 4- a.H.Bhattaoharyya, K.M.Ganeuly//Radiochimioa Acta 1986. Vol. 39. P. 199. 33d STUDY ON EXTRACTION 0? URANIUM(VT) WITH MIXTURES OP I l PHOSPHOROROANIC HXTRACTANTS BY KMH 31P METHOD LJL I E.A.Flllppov, IT.II.Mescheryakov, V.A.bagutenkov, M. V.Mlkheyev. All-Union Research Institute of Chemical Technology, Moscow, USSR A considerable part of literature on extraction is attributed to actinidea processed with phosphororganic compounds mixtures. However, the mechanism of synergistic extraction is not enough developed. Due to experimental difficul ties of metal complexes stoichiometry in the solutions containing mixtures cf phosphorcrganic compounds (РОС) interpreting results of extraction equilib rium and the conclusions of complexes composition still have no self-evident conception. It was the object of the present work to establish stoichiometry and con centration of the associates existing in extraction systems as dt-2-ethyl- hexylpnosphoric acid (D2H1PA) - tribui/lphosphate (TBP) (trioctylphosphino- xide (TOPO)), as well as complexes formed after extraction of uraniumCVl} from sulphuric acid solutions. For this purpose the HMR spectrometric stu dies on extracts and model solutions of the D2HJPA-TBP(TDP0)-U0.,S0. system 41 ^ (001. as solvent) were carried out. The "P HAR spectra were recorded with CXP-100 Bruker spectrometer, with 80% H.PO. as the standard. The problem of the mechanism of phosphororganic extractants coordination was solved with the account of hypothesis that quadrl-coordinated phosphorus atom takes part in bond-forming of its 3 orbitals. It was established for S2EHPA, TBP and other phosphates containing PO.-group that complex formation may be accompanied by screening intensification of-the phosphorus atom due to filling out its 3-d level by 2дг^З-.У electrons of the oxygen atoms.whicb do not directly participate in bond formation with an electron acceptor, e.g. 31P (КаВгВНР) • -1.0 ppm, 31P (TBP HNOj) . -2.5 ppm ( 31P (D2fflPA) • = 1.9 ppm 31P (TBP) с 0.5 ppm). The study on molecular association in the extraction system D2BHPA-T0P0 has shown that equilibrium existence of such complexes as TOP0-2D2EHPA, T0PO- D2EHPA and D2H№A* 2T0P0 takes place in CC1. solution depending on the com ponent relative contents in the mixture. In this case the formation of the hydrogen bound between D2EHPA and TOPO is accompanied by 31P acid signal shift towards the' stronger field region, similar measurements of the elect ron screening of D2EHPA and TBP functional groups of the phosphorus atoms let us deduce that the acid-base interaction is practically absent in thie system. 31 Analysis of P ЯМа spectra of the simulated systems Ho2(D2EHP)2(uranyl- di-2-ethylhexylphosphate)-TBP and иог(В2ШРЯ)г-ТОРО regarding the chemical shift and the relative integral intensity of phosphorus signals allows to determine the stoichiometry and the contents of the forming oompounds. The cited data show that in a solution containing uranyl di-2-ethylhexylpboe- phate and a neutral phosphororgattie base HPOC molecules take part in addi tional solvation of the salt molecules, stability and stoichiometry of the newly formed solvates considerably depend on electrodonating ability of the п phosphororganlo base (TBP or TOPO). Is the case о" и02( 2внР)г-ТВР system a comparatively low stability (K-20) of B02(D2EHP).TBP and U0j(D2EHP)j.2TBP complexes is the reason that a greater part of U02(D2EHP)2 salt and TBP are гг.Зак.1607 »» In a non-coordinated form in the solution. А «ее of TOPO as solvating addi tive leads to the complete shift of equilibrium towards formation of 2 4 UO2(D2EHP)2-T0P0 (K-10 ) and U02(D2*HP>2^-2TOPO (K*10 ) complete. At that time the appearance of signal in P NMR spectra of U02(D2EHP)-T0P0 system in a strong field region (-1*0 ppm) arid its intensity symbate variation regarding solvates concentration allows to suppose existence of complexes in two tauto meric forms: 2+ UO.• 2(D2EHP)2'nT0P0=S ^02«nTOP07 (D2EHR)g", where n» 1.2; with covalent and ion bonded D2EHPA acid residues. In the presence of TOPO excels an Increase of the medium polarity leads to intensification if ex change between the ionic and molecular forms of UO_..{D2EHP) *2T0P0 complex and to simultaneous Increase in.the ionic form-part /U022T0PQ7 •(D2HHP)|~• As compared with simulated systems in the real extracts prepared by shak ing of the organic phase with the uranyl sulphate water solution (pH * 2, £0(.Vl\/ a 20 g/dnr) some cisrepances in P ЫШ* spectra are observed only for D2EHPA-T0P0 system. In this case beside the main extractable U(VI) forms typical for simulated systems (IT02(D2KHP)2*T0P0 and U02(D2SIP)2'2T0P0 sol vates) one can also observe formation of TJO2(HS0.)2-2T0P0 and 0*0,,(D2EHP) (HS04)'2TOPO complexes. The analysis results of chemical shifts and phosphorus signals integral intensity of U02(D2EHP)2-D2EHPA system have been further on used to inter pret -3 P NMR spectra of the extracts with different uranium (VI) equilibric concentration in the organic phaee* It has been established that D2EHPA mo lecule polarization owing to P«0 group coordination to uranyl ion leade to intensifying its proton-donating properties, and, as the result, to format ion of a strong hydrogen bond. 338 PRECIPITATION AND SObVBMT КИНАОИОМ OP DBAHIUll (VI) И №•: 5_6j V.AvXazenko, V.V.Bagreev, L.M.Kardlvarenlco, V.A ?Macbuls!cii, OaB.Pavlovleh Industrial Mrm UHIEROHED, Sverdlovsk, Urals Politechnlcal Institute, Sverdlovsk, Vernadeky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Xoscow, USSR To Increase the effeciency of uranium recovery from acid hlghac- tive »sta of complex composition it is necessary to search the more se lective, bllghtly toxio and simply sinthesized organic reagents with im ported phyaJcal-chemicsl properties as compared to those used at present time. Host of the known extractants are not fit for the solving of these task, except for the some hi- and polyfunctions!, organopnosphorus and phoaphsrua-nltrogen-ceritalnlng compounds [1-3] • Some bifunctional phosphorus-nitrogen-containing compounds (PHCC) have been sintheeised whichhave proved to he effeetive reagents for ura nium (VI)« The composition of these compounds have been established by means of elementary analysis, thin layer chromatography and UV-, IR- end ШК-spectroeoovy ^го(он)2 "%о(он)г The interaction of PHCC «1th uranium (VI) it. sulfuric acid solu tions has been investigated. It has been found that PHOO precipitate uranium'(VI) selectively in presence of large amounts of lithium, cal cium, aluminium, iron, cadmium. The conditions of uranium extraction from sulfuric acid media tilth the solutions of PHOO in toluene, isoamil alcochol, tributylphoanhate have been established. The best results we re obtained tor the solutions of PHOC «ith octyl-radlcal in mixture of tributyl-phoephate and iooamyl alcochol. It has bean shorten that PHCC can be used for the Separation of uranium from rare earths, which are'nt precipitated with these reagents. References 1. Sohulz W.W., Navratil J.D.// Recent Development in Separation Scien ce/ Ed. Horroan H.Vol. 7. 6RC Press inc. Soca Raton, 1983. P. 31* 2. Ohmutova U.K.// Theory and Practice of Solvent extraction Hethods./ Ed.Alimarm I.P., Bagreev V.V. M.: Hauka, 1985.P.120. 3. Hyaaoedov B.P.// ISEC'SBi Papers. Moscow, 1968. Vol. IV. P.118. 339 ISOLATION OF NEPTUNIUM TRACES FROM URANIUM COMPOUNDS 5-64 BEHOVING THE MATRIX BY EXTRACTION WITH 1-PHEB]fL-3-araiHYL-4-BENZOY№YRAZOLONE-5 P. Zantuti, Та jura Nuclear Research Center P.O. Box 30878 lajura (Tripoli) Libya Yu.P.Hovikov, S.A.Ivanova, B.F.Hyasoedov, Vernadsty Institute of Geoohemletry and Analytical Chemistry of the Academy of Sciences of the USSR, ttoseow, USSR When determining the traces of JIp In uranium compounds by means of spectrophotometry and orystallopnosphoroue luminescence the chemloal treat ment of samples Is neoesaary union Includes either Isolation of neptunium or removal of the uranium maeroamounta. The paper illustrates the advantages of matrix removal whloh can be done Ъу extraction with 1-phenyl-3-uethyl-4-ben- zoylpyrazolone-5 (PHBP). Uranium and neptunium behaviour during the extraction by benzene solutions of PHBP from nitrate and sulphate solutions characterized by a high uranium concentrations was investigated. To prevent formation of a solid phase when contacting with РЫВ? solutions and in order to increase the factors of uran ium and neptunium separation synergic mixture of PHBP and di-2-ethylhexyl- phosphoric acid (02StPA) was proposed for uranium extraction. The following factors influencing uranium and neptunium separation were considered t solvent nature, molar relations and extragents' concentrations depending on the con centration of uranlub and acids. On the basis of the results achieved optimal conditions for uranium re covery were chosen and techniques for uranium maoroamounts' removal from nitrate and sulphate solutions were suggested. The techniques baaed on uran ium extraction by a mixture of- 0.1 Ы РИВ? and 0.1 H D2HIPA In amylacetate with preliminary neptunium stabilization in Rp(V)-atate. To separate neptunium along with its purification from Plutonium and uran ium fission products, for example, when isolating **Bp from neutron irra diated uranium, the reduction neptunium into Hp(IV) in aqeoua phase end ite extraction by 0.1 H РЯВР solution in Ъепгепе is applied. 340 LIQUID-LIQUID EXTRACTION OP THOHIUM(IV) ADD ШШИШСШ 5-65 Ж COMMERCIAL СНЕЫТШв EXTRACTAHTS s.Singh, C.R.Panda, V. Chakravortty, K.C. Dash.Department of Chemistry, utkal University, Vani Vihar, Bhubaneswsr-751O04, India The technique of solvent extraction is of great importance in the atomic energy Industry. Although alkaline leaoh process for uranium ores produces a good grade of mill precipitate, there are few satisfactory extractants for the extraction of uranium(VI) In presence of large salt concentration» at high aqueous pB /1/. Sons commercially available ohelating extractante, viz., Ш 26 (an alkylated 8-hydroxyquinollne) Л7, LIZ 54 (e j$-diketone deriva tive) /3,47 ап<3 ы' 84 (an oxlme-based reagent) /§/ have been auooessfully employed in the solvent extraction of thorium(IV) and uranium(VT). Extraction of uranium(VI) by 10$ Ш 26 and 10$ n-BuOH in benzene becomes quantitative at pH 5,0, The pH0 - values for the extraction of Th(IV) and U(VI) are 4*95 and 3.35, respectively. Quantitative extraction of Th(IV) by the mixture of О. Ш oxine and О. Ш salioylio add In ШВК «as observed at pH 5.0. From the results of studies on extraction of Th(IV) and U(VI) by mix tures of LIZ 26 (HQ) and DPSO the extracted species seem to be of the type iSbe2(I>PS0)2(SC3J)27 and /U02Q2(DPS0)7, respectively. The solvent extraction of U(TI) by Ш 54 (HA) and its mixtures with tri- n-butyl phosphate (TBP) show quantitative extraction by mixture of 5% Ш 54 and 5% TBP at pH 4.3. Prom regression analyses, the composition of the ex tracted species seem to be /UOg(CH)(A)(HA)(1BP)7. Quantitative extraotion of Th(IV) by the mixture of 10S6 LIZ 54 and 0.1И TQPO was noticed at pH 2.6. In fluence of various concentrations of HT1A and TOPO In their mixtures with LIZ 54 паз been investigated and pronounced synergism was notioed. Slopes of the linear plots using regression analysis indicate the extracted species to be possibly of the type ^Th(TxA)2(A)g7. Quantitative extraction has been observed for IJ(VT) by mixture of 10$ lit 84 and 0.1H dlbenzoylmethane at pH 4.2. However, only very little extraction has been observed 1л oase of Th(IT) by LIX B4 or its mixtures with other chelating extractaute or neutral donors. References 1. Rltoey e.H., Aahbrook A.W. Uranium and Thorium, Mineral Review H 53, Mineral Resources Branch of Car. // Dept. Energy, Vines and Resouroen. 1968. 2. Singh S., Panda C.R., Chakravortty V., Dash К. С // J. Radioanal. Bud. Chem. Articles. 1988. Vol. 120. P. 65. 3. Singh S., Chakravortty V., Dash K.C. // J. Radioanal. Duel. Chem. Ar ticles. 1988. Vol. 122. P. 137. 4. Singh S., Chakravortty V., Cash K.C. // J. Radioanul. Duel. Chnm. betters. 198a. Vol. 127. P. 349. 5. Mohanty R.H., Singh S., Chakravortty V., Dash K.C. // Solvent Extraction and Ion Exchange (oommunlcated). 341 SPECTROSCOPIC DATA OF TFS EXTRACTS IH CHLORINATE COBALT DIOAHBOLTOE (COD) ABB MATHEMATICAL DESIGN OP EXTRACTION PROCESS M.A.Afonin, T.V.Dronova, V.V.Korolev, L.N.Laaarev, Yu.A.Pokhitonov, V.V.Romanovsky, V.H.Romanovsky. Lensaviet Leningrad Technological Institute, Leningrad, USSR In CQ the similarity is the behaviour of three valence americium, cerium and europium on extraction by CCD is shorn. Since tiie study of macroconcen- tration of americium is accompanied by radiolyais of solutions, extracts, containing macroconcentrations of cerium (111) and microconcentrations of europium were used, as tile objects of study. The dependences of a chemical shift of two proton peaks of C-H bond of CCS on metal concentration in solution is determined by НШ-spectroscopy. The growth of metal concentration makes 7*02 m.p. peak to split into two peaks -4,36 m.p. and 6-7 sup, and to linear decrease of chemical shift of initial peak 7.02 m.p. The ESCA-spectroscopy showed, that in the complex with metal the bond energy of cobalt and chlorine electrons of CCS O.J eV higher, than that in H- form of CCD, the increase of the bond energy of cobalt and chlorine electrons is explained by the participation of the electron shell of these particular atoms in the formation of the chemical bond with Ce(III). The average number of Uganda in the complex n=3.01+-0.o2 паз determined by the quantitative m-epectroseopy at 1420 am band. Electrolytic conductivity of B-form of CCS and frequency-concontratior de pendence of dielectric permeability was determined by methods of high frequen cy dielectrometry and electrolytic conduction. It was found that the increase of С32 concentration from 0 to 0.; moVdir results in the decrease of dielec tric permeability of solution from J5.7 to 14.J, which was probably, a conse quence c.C destruction of hydrogen bonds between nitrobenzene molecules in the presence of dissolved water. Incidentally, the electrolytic conductivity in creased from 0.018 to 0.54 Oa m/mol. The rise of the metal concentration in the extract did not change dielect ric permeability of the 0,1 mol/dm' CCS solution higher than 4%. The dissociation constants Of nitrobenzene solutions of Ce(CCD}>were ob tained by the results of electrolytic conduction measurings. The dependence of the constants on the solution dielectric permeability was approximated by the equation ф*г> = S.6 * *.o f*f. *s -£) The frequency - temperature dependece of the Ce(CCD). solutions dielectric permeability In nitrobenzene wae also studied. Frequency (0.5-110 MHz) - cui- ceatratlon Ce(CCD), (0.0-0.0333 aol/dnr) - temperature (293-353 K) diagrams were obtained. Matrix registration of chemical equilibria, that are observed in the extra ction system, and stoiehiometrj data received by spectral and saturation me thods make up the basis of our mathematical model, Water phase contains the extracted metal ions, protons ana. nitric ions. She following reactions take place between Шеье species i л /*''•*/**%' ш Me/bo,), -*" fs) #*+ А%-ж tfrt?3 ft) The extraction of metals proceeds according to the ion exchange mechaaiam: 342 where В**is the CCD anion. Assuming that a est of extracted complexes is formed in the organic phase, the extraction of metal ions, that takes place according to the_ion exchange mechanism, may Ъе represented by the equation.- Mr*** *Mg"+*Л» =/*/«•£*,*'4!«s In the presence of polyethylene glycols the following reactions may take place j*fi«w- •* **& - /S2Ig **•**, A) *t>**lZ+j?M-*44'j»'*/b) Recording the equation (1)46) in a matrix form and using experimental concentration dependencies of metal distribution coefficients the system of material balance equations is solved. Determination of the concentration ex traction constants is carried out by the minimization of the aim function by Fletcher-Powell method CIS using experimental and rated values of metal distribution coefficients. !Ehe extraction constants of investigated metals that enable to carry out adequate description of the distribution in the wide interval of the reagent concentrations, were determined. The widening of the conditions of the extraction processes and the incre ased extent of mutual separation of components obtained from HA! require im provement and extention of suggested equilibrium model. One can see the ap proximate character of the model from the logarithmic rare earths distribu tion coefficients dependence upon the extragent concentration, which are the straight lines with slope 2. Such a dependence may be expressed by the following equilibrium (not tak en into account for in the modefli _/fe*S * Г = /*/.? - #+ » where /W^is the complex whose one hydrogen atom from the polyethylene gly col molecule or from the hydrate metal cation sphere is depleted. Moreover it is necessary to note that the composition of ttoe polyethylene glycol complexes in the organic phase may depend on both the type of polyet hylene glycol and its concentration /*/• Thus for low PEG concentrations in the organic phase the Heir*, HeI2£|* rare earths complexes predominate. For higher PEG concentrations these complexes further react with 1-2 PEG molecu les forming probably Mel|*, Mel^H^*, Bell*. Xhe increase of the rare earths concentration, for example, on concentra ting HAW also results in the change of the metal extracted forms concentrations. Thus one may come to a conclusion that further improvement of the extrac tion equilibrium model in the rare-earthe and Ф1Б separation processes by CSD extregents requires thorough studying the metal complex composition in the organic phase taking into consideration the above-mentioned factors. References 1. Benezova II. et al.// Beprint from "llangement of alphacontaminated waster" IAEA-S11-246/72. Vienna. 1981. IAEA. 2. Vanura P. et al.// Collect. Chechosl. Chem. Commun. 198$. Vol.50, IT J. P.581-599. 3. Fletcher В., Powell H.J.P.// Computer J. 196$. Vol.6, H 2. P.16J-168. 4. Vanura P. et al.// Collect. Chechosl. Chem. Commun. 1982. Vol.4?, IT 5. p.1444-1464.. 343 THB PITZBR BqUATIOH APPLICATION FOR THE OTROUHSCRIWIOS OP I g THE RARE EARTHS AKD IBS BXTRACIIOH BY THE CHLORINATED COBALT I Z DICAHBOLYDB ЗОЫрт'ОНЗ I.A.Burteev, V.V.Korolev, V.w.Romanovsky, V.M.Sedov. Leneoviet Leningrad Technological Institute, Leningrad, USSR She chlorinated cobalt dioarbolyde (COD) solutions in nltrobensene are used for selective extraction of cesium, strontium, rare earths and TIE from nitrio acid solutions П?. Sue extraction of metals proceeds according to the cation exchange mechanism with the formation of HeBncomplexee in the organic phase, «here В is the CCD anion /27. She traditional approach to the circum scription of equilibria in such extraction systems Is based on the joint ana lyses of the systems of the active masses la* and the material balance equa tions, which describe both the heterogenous extraction reaction and the total combination of the homogeneous interactions, which exercise the essential in fluence on the deviation of the organic and water phases properties from the ideal behaviour Ci!. She difficulty of the quantitative calculation of the dissociation processes In the organic phase Л7, the necessity of the employ ment of large number of the concentration constants of the nitrate complexes formation in the inter phase, and also the bulky mathematical apparatus, whloh takes much machine time are to be attributed to the shortcomings of such an approach.. In the present work it la shown that the indicated difficulties may be avoided if the average ion activity coefficient» are used for the circumscri ption of the reaction of the extraction. She dependence of the average ion aotivlty coefficients from the concent ration composition of the equilibrium phases may be circumscribed by the Fit ter equations Й7. She Pltser equations parameters, which take the properties of the metal nitrates water solutions into consideration have already been dlscribed {§-&!. In the present work the Pltser equations are used for the calculation of average ion activity coefficients in the organic phase. She methods of eearch of the corresponding parameters whloh are based both on the results of the extraction measurements and cm the application of the Independent analysis methods ware developed. It is shown that the developed mathematical model satisfactorily olrcumsribes the extraction of rare earths and 115 in macro- quantities. She thermodynamic extraction constants of the individual elements are calculated. Deferences 1. OalklnB.Xa. et al.// ISBC'88t Papers. Moscow. 1988. Vol.17. P.215-218. 2. Podslmek I. et al.// J.Inorg. BTucl. chea. 1980. Vol.42, S 10. P.1481-1486. J. Bvseyev Д.И., Hikolayova £.8/Vatematieheskoye modelirovanie himicheakUi ravnoveily. *.: ПОП, 1988. 192 e. *. Kakrllk 1., Tenure P.// Salanta, 1985. Vol.32, Я 5. F.42J-429. 5. Pltser K.8. et al.// J*amer. Chen. Boc. 197». Vol.96, H 18. P.5701-5707. 6. Pitaer K.8., Mayorda G.// 3. Fhys. Cham. 197?. Vol.77, Я 19- P.2300-2J08. 7. Pitaer t.8. et al.// 3. Sol. Cham. 1978. Vol.7, IT 1. P.45-56. 8. Burtsev IU.. et al.// Badlokhimlya. 1988. T.JO, (J 6. S.857-86S. 344 SEPARATION OP THE ACTHJIDES PROM CARBONATE SOLUTIONS BY EXTRACTIOK 5-68 AND EXTRACTION CHROMATOGRAPHY Z.K.KsrslOVa, T.I.Bukina, E.A.Lavrinovlch. Vernadsky Institute of Geochemistry and Analytical Chemistry of the Academy of Scienoee of the USSR, Moscow, USSR Actin!dee in carbonate solutions form various complex compounds, the con tent and the stability of which being affected the concentration and rela tion of the components, the pH value and other factors» The formation of the anion complexes of the following composition is typical for TfE: [Am(CO,)2j~ 2 3 (lg^»11.44h [Ат(С0э)2(ОН)] " (lg/«15.56>» [Am(C03)3] " (lg/=13); 4 € 6 [Am(CO3)3T0H)J "j [Am of ion associates of (RNH4)3[M(C03)31 composition including metal tricarbo- nate complex as anion {2], Arainomethylderivstives of alkylphenols (DEAF, СААР), allorlpyrocetecholes (DOP, TAPJ^-diketones (PhMBP, HTTA) extract tri- valent TPE in the form of intracomplex of the type of M(PhMBP),nHaO; ИСТТА),- 2 n ла nH20i NagfMDOPgCOHXHgOjJ " /2-3/. * * * oase carbonate-ion is not the necessary component of the extracted compounds, but only a completing agent, which confines the hydralizing elements in the low alkaline media in the so luble form. Since the extraction process of the intracomplex compounds and the disintegration of the complex compounds in the aqueous phase same time, "the role of the kinetic factors, especially in metals with alkylpyrocatechoi, is essentially increased £ 2j« As the experimental data show, the rate of mass transfer is determined by slow chemical reactions, which take place both in the volume of the aqueous phase and at the phase boundary. Although the in crease in the pH of the initial solution facilitates these reactions, the possibility of the formation of the interphase film grows. To avoid the accu mulation of the products of hydrolytic polymerization in the zone of the re action the extraction should be conducted with high content of the alkaline metal carbonate. The most part of the studied extractants rather highly ex tract both macro- and microemounts of elements from carbonate solutions. At the same time the extracts, saturated with metals, based on DA, PhMBP, TAP, with the concentration of the order of n*10~ M, can only be obtained by con centration, since TPE carbonate compounds are comparatively poorly soluble in carbonate solutions. Extraction from carbonate solutions can be ueed not only for TPE isolation,but also for their separation.Like in the case with alkaline solutions, the sequence Of actinide isolation from carbonate solutions is de creased in the series M(IXX^M(XV^M(V)J>]l(VI)s according to the degree of oxidation* It is clearly manifested in Bigs.1-3 where the comparison is made between the metal extraction with alkylpyrocatechol, y$-diketon and condensed alkylaminophenol. Since hexavalent and tetravalent elements are extracted worse than trivalent elements, in these systems rather high separation fac tors 345 lOgD logD JSSZr—' —*Am" C J-°5 K2C03 Fig. extraction of metals from KPCO, (?;') solutions and the mixture of and ГЛ KOH ("**) by 0.04 Г.1 DOP in toluene Pig. Extraction of metals from K2C0, solutions with 0*1 К PhfiOP in. ГЯВК Pig, extraction of metals from K20O-j solutions (pH 13-4) 0.1 M СААР in CC1. tion in the systems DEAP-KgCO^ (KOH) and DOP-KgCO., (KOH) one can enhance both the factors of TP3 separation from fission elements and also the factors of americiura separation from berkelium, cerium and other elements* except europium (DAm/Dgu^2). Among the agents tested for the extraction separation of Ara-Cm, TAP is practically the only agent, which extracts curium and californium from carbonate solutions better than americium (Б- /D.=2»2)»- Additional possibility of separating these elements occurs during the re-extraction by potassium car bonate mixture and salts of arainopolycarbonic acids. It was established that the DTPA content effect the rate of the re-extraction of the elements essenti ally. The increase in its concentration at constant KgCO-j content leads to a sharper increase in the rate of curium re-extraction against amerioium. The ef ficiency of the separation of trivalent elements grows during the transfer from a single static extraction to extraction chromatography* By varying the content and the rate of the penetration of the solution through the column with fluoro- plaat-4, impregnated with 5/S-TAP in toluene, the fractions were obtained at the stages of sorption, washing and desorption, containing 86.3$ of curium and 1 .as of americium. In the system DEAF (CAAP)-K2C03 (KOH) one can separate TPE in the various oxidation states /Cm(III)-Am(VT)/. The extraction chromatography gives a chance to separate elements at the stage of filtration of the initial solution through the column with fluoroplast-4, impregnated with 0.3 M DHAF or 0.5 СААР in hexane* Under these conditions Am(VI) is reduced to Am(V) and penetrated into filtrate, while Cm(III) is remained on the immovable phase. The fraction was ob tained at the stage of elution, containing ~-99«67& Cm and 0.1?$ Am from initial amount. Referencee 1. Bidoglio G.H. //Radiochem. and Hadioanal. Lett. 1982. Vol.53. P.45. 2. Karalova Z.K.«Myasoedov B*F..Bukina T.I.,Lavrinovich E.A. //Solvent and Ion Exchange. 1988. Vol.6. P. 3. Karalove Й.кГ et al. /ЛЗЕС'88: Papers. Moscow, 1988. Vol.IV. P. 150. 346 ISOLATION OP RADIOCHailCALLY РШШ 239Mp PROM j 5-69 NEUTRON IRRADIATED URAHIUM BY COMBINED BXTRACTIClT" CHROMATOGRAPHY AND AKION-SCCHANGE METHOD S.H.E1 ffaer, A.V.Ananyev. Tajoura Nuclear Research Center, P.O.Box 30878, Tajoura (Tripoli) Libya in neutron flux of nuclear reactor. Being isolated in a radiochemically 239 237 pure state carrier-free Np can be used as a model of longlived Np for carrying out separation experiments and study of some chemical 239 properties. .We worked out the method for quick Isolation of Np from irradiated uranium. The method consists of two steps: Extraction cinematography isolation of neptunium with 2-thenoyltrif luoroacetone 1НГЕА) and finally anion exchange purification. A few grams of ttx. 13 -2 -Л irradiated in neutron flux 5.10 n. en sec. during ю hours were dissolved in nitric acid after 14 h. cooling. Acidity was adjusted to 2 mol/1 HNO. and neptunium was stabilized in tetravalent state with hydroxylamine. Then the solution was passed through the column with 0.S nol/1 HTIA in xylene an silanized eilicagel. After washing the column with 2 mol/1 HNO, neptunium was desorbed with 6-9 mol/1 «JO,. Oesorbate which still contains a noticeable amount of 2ircanium was passed without preliminary adjustment through the second colum with anionite Dowex 1. The colum was washed with 8 aol/1 HNO, and neptuniura was desorbed 239 with 0.5 mol/1 tW>r PurificaUon of Np from Zirconium and other fission products was controlled by У -spectrometry method. Radic- chemical purity of the obtained Np samples is 98-99%. Chemical yield of neptunium not less than 90%. The laboratory set up for reprocessing of gram amounts of irradiated uranium with the 347 TUB STUD* 0? IS01ATI0H ABB SBPAHATIOH mOCESSES OF THS TRAH3PbUT0Bimi|"~—[ H.¥u.Krenliakova, K-V.Bareukova, A.P.Hovilcov. Varaadaky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Moscow, OSSH The use of TVH (copolymeric matrix containing eitractants In drop-liquid state) far element isolation and separation is considered to be perspective Д7- It Is due to their Ugh capacity, simplicity of column preparation and to the possibility of durable usage without a loss of capacity properties of •orbents. In tola work the extraction chromatographic behaviour of trivalent ameri- CIUH, curium, berkelium, californium and europium, as well as tetravalent be- rkeliua and plutoniun and hezavalent uranium on TVBZ, containing tributylphos- phate(TEP), trioctylphosphine oxide (TOSO), di-2-etbylhexylpbosphonic aoid (HDBBP), mixture of IBP and ШЯВР (1:1), polyalcylphoephonitril acid (PAIHA) and trioetylanise (I0A) In nitric acid solutions ( 0.01-12.0 M/1 ) have been studied. The possibility of trivalent Bk and Of separation from Am and Cm on IVBI- ШШНР is demonstrated in Mg.1. In sta tic conditions at Qffl0^»0.2 m/1 вера- ration factors of Bk/Jm and Of/Am pairs are equal to 20 and 17, correspondingly and separation factors of Bk/Am and Of/ Cm pairs are equal to 17 and 11.; as well-During the proeese of gradient elutlon from the column of 6.5 am leng th and 0*4 em diametre the separation factor of Am and Cm from Bk and Of con sisted 4-102. The separation of Am and Flg.1. Separation of Am from Bk and Bit is better to carry out on 1ТШ-ТВР: Cf on TVBX-HDEHP in 0.2 И HHOj HDBBF, americium fraction containing less than 1 К of europium during elu tlon process by 0.05 M/1 HHOj. IVBZ, containing IBP, ТОР0, HDBHP can Ъе ap- plyed for isolation and separation of tetravalent Pu and Bk and U(VI) from other transplutoniua and rare-earth e- lementB. For example, static separation factors of Pu(IV)/Am(III),Bu(III) at 2 [НВ033»7,0 M/l IS more than 10 and 10? for TVBX, containing IBP and Х0Р0, cor respondingly» This permits to carry out 2 A 6 8 10 12 ННЛЛ a high effective purification of Pu from aaaosiating impurities in dynamic Pig.2. Dependence of Pu distribution conditions. coefficients on BNO. concentration Several simple» of TVHC-TOA with эх- tractaub content equal to 65-70 % of tott.l weight were synthesized for the 348 first time- The photographs of mieroetruoture of TVKX wars made and it was es- tabliehed that TOA «as la drop-liquid state in ЭТИ pores. It *as shown that during the synthesis of IVK1-T0A with the use of solvent, the introducing of extractant in matrix took place» there what deaorbing eharaetertatlca of VVK decreased* TVBX-TOA is quite seleotiYe in respaot to Pu(IT) (Pig.2) and is con sidered to Ъе тагу perspective for its usage in purillcation of waste solutions and plutoniua determination in waste and natural waters. For the purposes of waste solutions purification fro» radioactive elements ТУЫ-РАРЯА can be also used. Distribution coefficients for all studied ele ments during the sorption by thia ТУШ are very high: fromlO to 10^. TYsX- PAPHA can be also recommended for concentrating from strong acidio ( to 18 M/l) solutions. The main phislco-obemleal charactherlatia of styren-divlnylbenzene matrix were discussed in Г27. In the present work the equations in spheric coordina- nates describing mass transfer from the center of IVEX nuclear in extra- and intar-dlffisios areas have bean obtained on the base of differential equations solution of non-stationary diffusion with the uae of approximate Prank-Kamsne- taky method /3/. Holeoular diffusion coefficients of europium di-2-ethylhexyl phosphonate in pure HDEHP Jias been calculated on the baas of these equations. Its value consists M ОГ'в what in the first approximation corresponds to that obtained by Horwitz fy/. This supplementary proves the drop-liquid state of extractant in TTBX pores. Thus, the present work shows that TYBX containing extractants of different classes can be successfuly applied for the isolation and concentration and se paration of transplutonium and rare-earth elements from nitric acid solutions of wide range of concentration both for analytical purposes and for technolo gical tasks. References 1. Bolotov A.I., Kusovov lu.I., Kodubanko L.K. et al.Avt.avid.476279 (1975). Bul.izoor.N 25 (1975). 2. Korovin V.Yu. et al.//Proc. ISEO-SS. 1988. Moscow. Vol.3. P.159-162. 3. Taxaaov V.V. at al. //Klnetika extraktsii neorganiohesklh'veaoheatv. Itogi nauki i tekhniki. Ser.Ifeorgan.khimiya. B.: VMITI, 1984- Т.Н. S.85. 4> Borwitz B.P. and Bloomquist A.A.//J.Inorg. Nucl. Chem. 1973. Vol.34, Я 12. P. 3851-3873. # 349 SEPARATIOH OP AOTnriDBS BY USISG 0? TWO-PHASE AOUBODS SYSTEM BASED-—Г OH POLY(ETHYLBHE 8LYC0L) I L- D.P.UoloahniJcova, V.U.Shklnev, V.Ya.Krenk*:., Vernadsky .Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR Two-phase aqueous systems based on poly (ethylene glycol) (PEG) пате Ъееп used for the extraction of actinid.ee from various media. Only few extractanta are known that extract the aetlnidaa from their Airbonmte solutions. Aqueous systems based on PEG have Ъееп found to Ъе capable of effectively isolating and separating elements from carbonate solutions of vary high concentrations ("3.0 H) is the presence of conplexing agents of the phthalaxone type. In the presence of allzerine-oomplexone (AC) as ohelacing agent, plutonlum is extrac ted quantitatively into the PEG phase from sodium and potassium solutions Table 1. Distribution coefficients Ctable ' >• ^ ««*•»•««» *•> «» deg- of aotinides by extraction with PBO "9 of №<**»* extraction from po- from carbonate solutions in the pre- ta3elum aa4 eodlun «Л»"*» is, pro- sence of compHxing agents ЬвЬ1У» «»l«inea by. different salting -out action of the cations. Trivalent AC ZO transplutonium elements are extracted Element most effectively under these conditi NttjOO-j KpOO, K2oo3 ons, A weak extraction of penta- and Ill l 138.0 31.5 68.0 hexavalent aotinidee allows to sepa 77.4 13.4 0.05 rate plutoniua from uranium and nep 2.04 0.15 0.09 tunium with separation factors of ca* 0.46 0.05 0.02 3.102 and 90, respectively. Under these conditions, neptunium ean be separated from trivalent actinides and lanthanides with separation factor more than 3.10 . It can especially effectively be separated from curium and einste inium. Seperation of neptunium and Plutonium from trivalent sctinidea oan most effectively be performed in the presenoe of one more phthalexone, xylenol orange (ZO) (Table 1). She separation factors for these elements are then equal to 1.3. 103 and 8.10 , respectively. A low degree of neptunium extrac tion fro& carbonate solutions in the presence of xylenol orange has been ta ken an opportunity to develope an effective prooedure for separation of ame- rlctum-243 from Its dauther deoay product, neptunium-239. The epectral datai obtained show that all americium being transferred into the PES phase. Pure neptunium remains in the carbonate solution after the extraction by PES In the presence of xylenol orange (2.1'0~2 H). The separation factor for ameri cium and neptunium is 3.9.TO2. The higher degree of amerlcium-243 purification, from dauther neptunlum- 239 has been achieved using a PES <- ammonium sulfate - water— Inorganic co- mplexing agent (potassium phosphotungatate) system. Using this system allows to obtain an Isotope generator of naptunium-239. The f-spectra of the initial solution and PEG sad the salt solution after the extraction are sbown in Pig. 1. The separation factor of amerioiua. from neptunium is ea. 2.10-5'. Ren* tunium accumulated in the PEC phase oan be stripped using aqueous smmonlum 350 sulfate solution (Pig. 1. •j-apectnun dl. In the presence of potassium phospho- tungstate, tetravalent aetinides alongside with trivalent ones are quantita tively transferred into the PEG phase from sulfate solutions, however, with lower distribution coefficients (Table 2). For this reason Plutonium la вера- Table 2. Distribution coeffici i ents of aotinides by extraction with PEG from salt solutions in the presence of 1.10--5 И pw Element Salt solution (»H4)2SO4 (нн4)гНР04 An (III) 131.5 6.66 4 LAA PU.CIV) 4.5 0.25 B.KeV 64 126 Hp(T) 0.06 0.02 0(VI) 0.19 0.44 4 о Separation factor Am/Up 2200 370 Am/D 690 15 Am/Pu 27 Pu/Jftl 75 Pu/B 24 rated from neptunium less effectily. Fig. 1. j-Spectra of the initial 2 3 The possibility of separating ac- * Am solution (a), (HH4)2so4 solution •tlnldes in various oxidation states (b) after extraction by FES in the pre has been studied пв1пв both sulfate sence of PW. PEG solution (c), sulfate and phosphate systems in the presen- solution with accumulated гэ%р strip об of potassium phosphqtungstate ped from the PEG phase (d) (Table 2). The results obtained show that the extraction of aotinides Pu(IV) from phosphate media is far lower than from sulfate ones* Using arsenazo III as a comple- Xing agent in FEB - ammonium sulfate - water system makes it possible to extract plutonium quantitatively еы. 98% into the PEG phase over a wide range of рЯ values (Fig. 2) -and se parate it from trivalent actixildes -1 and lanthanides with separation fac 2 3 4 5 pH г tors of 10 at pH a 3. Fig. 2. Extraction of elements by PEG in thj presence of 1.1o—' M arse- паго Ш as a function of sulfate so lution pB Thus, two-phase aqueous systems based on poly(ethylene glyool) and contai ned various water-soluble complexing agents are effective for quantitative extraction of the actlnldee and their separation from different solutions. 351 ACHIEVEMENTS AND PROBLEMS IN INVESTIGATION OP REDOX REACTIONS OP I . -2 TRANSURANIUM ELEMENTS 1_ N.N. Krot. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR The redox reactions of the transuranium elements (TUE) have been and remain up to nowadays an important trend of investigations in the actinide chemistry* There are significant achievements as well as many unsolved problems in this field. A short dieCUBSion of some of them ia Just a subject of the present report. First of all it is necessary to note that a greet experimental data have been published and they concern the determination of kinetic characteris tics of the TUE redox reactions with the different reagents in the water mo derate aoid solutions. These data present a base for certain conclusions about probable reaction ways and chemical nature of intermediate products of the reductant. and oxidant transmutations. A subsequent development of views on the charge transfer mechanism and the influence of the TUB ion forms and the composition of solutions on this meohanism represent an important problem in this field* A number of publications deals with the study of the TUE redox reactions in media containing strong complexing reagents or high concentrations of salts. The stabilization of unusual TUE oxidation states and change of the process of redox reaction have been often observed under such conditions. Very interes ting results have been recently obtained by investigation of the TUE redox processes in organic solutions in the pre в en с в of strong Uganda. This ap proach веете to be very successful but it is insufficiently explored. In particular ii is desirable to study more thoroughly the TUB exis tent forms in organic solutions, the oxidation potential systems of diffe rent ion pares, the influence of small water concentrations on kinetics and mechanism of the redox reactions. Concerning other investigation trends of the TUE redox reactions, where many unsolved ргоЫетв exist» it should be noted: 1. The study of the TUE redox processes in the presence of the homogeneous and heterogeneous catalysts. 2. The investigation of the influence of the TUE redox transformation on kinetics and meohanism in different media under light and ultrasonic action. 3. The study of the TUE via lent transition in solid compounds and hetero geneous systems. Realisation of the mentioned investigations will promote further develop ment of actinide chemistry and the solution of a number of practical tasks. 352 KINETICS OP SOME OXIDATIOH-REDUCTIOH REACTIONS OF ШАНГПИ AND 5-73 NEPTuHIUM IH ORGANIC TEIALKYL PHOSPHATB SOLUTIONS V.S.Koltunov, 7.I.Hexoh.enko, K.M.Prolov, H.Yu.Sinev, K.P.Shepel'kova, S.P.Rodyushkin, 0.1.Zhuravleva. All-Onion Research Institute of Inorganic Hater ials, Moscow, DSSR Investigations into valence changes of IT, Up and Fa in an extractant phase can serve the basis of a neif principle of the separation of these elements in the process of spent fuel reprocessing* This paper discusses the kinetics data on the reactions of 0(IV) and Up(IV) oxidation with nltrlo and nitrous acids in TBP solutionis as «ell as the U(IV)-Hp(VI) reaction in triisoaayl phosphate (TIAP). The u(IV)-HK02 reaction in a perchloric acid solution of TBP obeys the equation of the first order in both the reagents and the dependence of its rate on H*—ion concentration is similar to that observed in the aqueous so lution of H0104 ЛЛ -d/6(iv)7/dt - ^u(ivE?./HBoa7.(K1/^a:t7 + V&'!7. <" then KIt., -— (0\V.. m0.06)min"I IJrtWO/UUU 1 anBUdU K«lg- . ( 4.68+0.21)l2/m /H,0/ • 3.0 mole/1. Kinetic equation (l) agrees with the meohanlsm postulat ed for a reaotion in an aqueous solution £lj and involving the slow stages: 3+ U0H + HN02 -» UO^ + NO + 2H* (2) U*+ + NU+ + 2HgO-t- UOJ + Я0 + 2N0 + HH03 + HgO ;£ 3HH0g С 5) to the elde of НПО* formation. The kinetic equation of reaction (4! has the form of: 8 -a<5?(iv>j/dt - E1-Zu(ivJ7-/so5/-/&t/ + х2Д><пг27чФног//2и+7, (б) where K., • (4±1)-Ю"г l^nol&.min and Kg - (1.95±0.23)т1п_1 at 55°C and ZH2Q7 • 3.0 mole/1. The variation of К with a temperature corresponds to the activation energy Eg • (70.7+З.В)Ы/шо1е. Hoxavalent neptunium Is stable in nitric acid solutions of TBP in dodecane including the presenoe of nitrous acid as opposed to the aqueous solution in which the Hp(VD-HH0g reaction proceeds at an appreciable rate /17. In nitric acid solutions of TBP neptunium (IV) oxidizes to Hp(V) and Bp(VI). The rate of this reaotion is expressed by the equation: -d^p(r/)J/dt . К-Д1р(11Г)/-/5вР7//ШЮэ7 (7) where К - (2.45±0.75>-10"* min"1 at 60°c. The activation energy of the reac tion is E . (107+14)kJ/n»le. гз,3ак.1607 353 Os interaction between Up(VI) and uranium (IV) in nitric acid solutions of MAP dodecane a quick change of Kp(Vi) to tip(V) ia observed that is follow ed Ъу а alow stage of the reduction of Hp(V) to ITp(tV) the rate of which obeys the equation of the second order: d^p(iv)7/dt • k'./5fp(v)7.Z6(iv}7. (e) The dependence of the rate constant K' on the HHO- ooncentr&tion ia given by the extreme function with a minimum At 25°C and ^5lA?7 • 35%): £S№^, 0.09 0.14 0.20 0.24 0.28 0.45 0.56 0.65 0.79 0.83 mole/1 It', 4.6 4.1 2.9 3.3 2.1 2.0 2.4 3.8 4.3 5.7 1/mole.min The activation energy of the reaction is В • (45.S+15-9)W/mole. The NptV)-U(IV) reaction has been also studied in an aqueous solution with the aim of refining the kinetios parameters and comparing the latter to the data obtained in MAP. It io established that in the QsoJ range « 1.25- 6.0 mole/1 the reaction rate is described by the equation: 3 dZSp 354 FORMS OP EXISTENCE ADD STABIblTY IP HIGHER VAbEHT STATES I OP TRAHSURANHIM ELEMENTS IH ALKALINE MEDIA I ' I.G.Tananaev. Institute of Physical Chemistry of the Academy of Sciences of the USSR, tloaoow, USSR The discovery of heptavalent forms of actinldes has given a new impetus to the studies of the behaviour, of transuranium elements (TUB) in alkaline media* However, despite the progress made in the (study of the forms of existence and redox reactions of TUB in alkalis many problems in the given field remain unsolved. This refers, mainly, to hexa-and jsentavalent forms of the elements. Taking into account these facts, we performed additional studies of the behaviour of higher valent forms of Tti> in aqueous and aqueous-organic solutions. The elucidation of the forms of existence of An(VI) and (V) («here An=Np, Pu and AD) in media with different concentration of alkalis, the study of the stability of Ир(VI) as regards its self-oxidation and self-reduction in alkalis of various nature, in the presence of organic solvents and in alkaline melts «ere the objects of our research. The stability of Hp(VII) in alkaline aqueous-organic media and in some solid compounds during a long storage was also under study. Plutonium (VI) and americium (VI) in alakline media over a wide range of COK~/ have been established to exist in the form of AnO,(OH)|~ ions. Fenta- valent neptunium and americium have the analogous ionic form, but with a different oharge. The study of the reaction, of disproportionation of neptunium (VI) showed, that the degree of the completion of this reaction depended considerably on the chemical nature of alkali. In KOH and CsOH the equilibrium constant of the above-mentioned reaction is noticeably lower than that in HaOH. This is accounted for by the difference in the hydration energy of Ions of alkaline elements and by the change of the thermodynamic activity of neptunium ions. Upon the introduction of the organio solvent, e.g. methanol, to the reaction medium the equilibrium of the disproportionation reaction shifts to the right. This leads to the appearance in the Bolution of Np(VII) already at relatively low concentration (~5 mol/1) of KOH. In alkaline solutions the reduction rate of Np(VII) by alcoholu strongly depends on their chemical nature. Secondary alcohols are more aotive ae oxidizers, while tertiary aloohole- reaot slowly with Np(VII). It was shown by the method of measuring magnetic permeability, that the compounds of the type ШрО^.п^О (where itWLi, Na, К and Cs) were rather stable during, air storage. The accumulation of neptunium (71) in CsNpO. after a 3 months "storage was not observed. In the case of IilSp0..2Il~0 and HaHpO.. H,0 2-3SS Hp(VII) transform into the hexavalent state after a month's storage, 355 ACTINIDE VALENCE STABILITY IK SLUORIDE MEDIA i-75J F.Gary Slier, K.D.Abney, L.R.Avene, W.H.smith, S.A.Klnkead. Los АЙйоБГ National Laboratory, Los Alamos, New Mexico, 87545 VSA T.A.O'Donnell. University of Melbourne, Parkville, Victoria, Australia Recently It has been shown that concentrated actiniae solutions can be formed over a wide range of valence states (III-VI) in fluoride-based media. High solubilities are favored by extreme acidity (E.G., SbFg/HP) or basi city (E.G., blfluorlds melts) and significant differences in metal ion coordination and ohemistry accompany the enormous acidity differences. In this paper we will discuss recent experimental results pertaining to actlnide reaction chemistry and electrochemistry in such media with particular emphasis on valence stability as a function of acidity. 356 •^5i_ THIPBRATURE AND IONIC STREWGHT INFLUENCE ON U(VI/V) ^f$ AND U(IV/III) 1— REDOX POTENTIAXS IH ACIDIC AW) CARBONATE AQUEOUS SOLUTIONS H.Capdevila, «P.Vitorge. Laboratoire de Chimie CBA IRDI/DKRDCA/DRDD/SESD/SCPCS- 92265 Pontenay-aux-Soaea cedex France - The redox potentials of -Uranium fl) nave recently been reviewed and measured to assess the behaviour of tills radioelement in the environment, inside and around waste disposals (in geological stable formations). The ionic strength of aqueous solutions used for the electrochenical measurements of redox - potentials is much higher then in deep groundwaters : the Single Interaction Theory (SIT) can aadelise the activity coefficients |1-2) of cations with reasonable precision (except, perhaps, for the highly charged tetravalent ones [2]). Cranium has been used to validate the method (cyclic volСашеtry) and to modelise the behaviour oC the other aetinides [1] ; these predictions have then been verified experimentaly for Plutonium and Neptunium (2). In several types of groundwaters, actiniae soluble species (that can migrate) should oxlst as oarbonate complexes [3] : there are very few experimental evidence [4] that the SIT can be used for these anionic species. The poor precision of published results on the entropy of actinide cations induces important uncertainties on the redox potentials at temperature higher Chan 25'C [2] (as in groundwaters). Ue have then decided to measure (using cyclic voltametry} : + + the redox potential of Uuf / H0£ and U* /Uncouple in НСЮ4 1Н solutions versus temperature to verify entropy values ; the jedox potential of UO^CO^^/UOgtCO,)!" to test the SIT (at different temperatures) with these highly charged anionic limiting complexes of hexavalent and pentavalcut uranium that exist Ln concentrated carbonate solutions [**5J. The experimental set up for cyclic voltametry measurements [1-2], the method to prepare the solutions in acidic [1] and carbonate media [4) have been previously described. Uranium total concentration was 1 iH ; it was hexavalent in the bulk solution even to neasure the cedox potential of reduced species, as In (2). In acidic medium (HC104 IK), we verified the published normal potentials: E"IU0|V U0£] • 60*j mV/HHE E"(u*+/U5+| - -63OT4 nV/NHE * to whom correspondence should be adreased. 357 From S to 55°С the variations of the potentials of these couples, measured against Ag/AgCl electrode, are linear ; the entropies are then constant : (^[II0§+/ Oof) - US[Ag/AgCl])/F = 0.050.3 nV/'C (U5[U*+/U*+] - USlAg/AgCl])/F = 1.5*0.3 mV/'C In carbonate medium (Ne^COj 0.2H), the SIT Is confirmed from 5 со 5S*C and up to X = 2M, the redox potential o£ U02 (CO^'/IK^ (C03)|~ couple is : E(T,I) = E(T.O) + ( dfi(T) m + 9 ».(T) чТ/(1+1. 5\IT> )RT/F where a is the molality of Na+ (mole/1%), I the ionic strength due to Na2COj and NaC10£, T the temperature. RT/F = 59,16 mV at 25*C. a(25> - 0.5091 at 25*C and vary with T [6]. E(T,0) and u£(T> are fitted : Б£25,0> = E'[00eCC0s)|"/U02 + + Ле(25) = cIU02(COj)5",Na ]-€|UOzCC05)|~,Na ] = 0.92 kg/mole aStUOjtCOj^/UO^COj)!-] /F = -1.8+0.5 mV/'C te'(T) = ££ References 1. Ch. Riglec ; P. Vltorge ; I. Grenthe.Inorg. ctiim. acta. 133. 323-329 (1987). 2. Ch. Riglet ; P. Robouch ; P. Vicorge. accepted for publication in Radiochlm. Acta. 3. P. Robouch. R CEA 5473 (1988). u. I. Grenthe. J. Chem. Soe. Dalton Trans. (1964) 5. I. Crenthe ; P. Robouch ; P. Vitorge. J. Less. Common Metals, 1£2, 2S5-31 (1986). 6. I. Grenthe, H. Wanner. Thermodynamic Data Bank, 0CDE HEA TDB Guidelines for the Extrapolation to Zero Ionic Strength, to be published in the first volume of Т0Д (Uranium). 358 •V,»<1??6*» THE INPLUENCB OF ULTRASOUND ON REDOX REACTIONS 0? ACTINIDE IONS IN AQUA SOLUTION [wf] M.V. Hikonov, V.P. Shilov, N.H. Krot. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR During the systematic lavestigstion of eoDochemieal reactions of actini- des in aqua solutions it has been found, that Np(V) and Pu(IV) in perchloric acid media under ultresound influence (frequence 44kHz, intensity- 1W/cnr) at 18-20°C transform slowly into +6 oxidation state. The reaction rate increases according to the increase of HC10. concentration* It a chives 1.2.10 mol/dm .h end 0.6 mol/dm3«h for Np(V) and Pu(IV) respectively in 6 mol/dm3 of HClO^.Tbe reaction order approximates to zero in both cases* Np (V) also oxidates slowly Np(VI) in э mol/dm3 of НЫО. under ultrasonic influence. In the ease of Pu(IV) in HHO., media this pro сева is absent. 10"3 mol/dm-3 solutions of Am(V) in 0.5 mol/dm^of HC10. or HNO- reduce slowly to Am(III) (about 10# in HN03 and about 20# in HC10. during 2 hours). The stability of Am(V) increases due to the inc rease of acid concentrations. Am(VI) under such conditions reduces to Am(V) faster than for 10 minutes» The ozone barbotage through 5.10~3 mol/dm3 of plutonium solution and ultra sound influence together at 18-20°C provoke oxidation of Pu(IV) to Pu(VI) in 1-8 mol/dm3 of HNO.,. Under the influence of ultrasonic waves the reaction process is three times faster than without ultrasound in 1 mol/dm of HNO,. In 1 mol/dm3 of HNCU Am(V) also oxidates to Am(VI) by ozone. The rates of both sonochemical reactions are of zero order by metal and have been found as 2.16.10-3 mol/dm3h and 1«92.103 mol/dm3h for plutonium and etnericium respectively. The attempts of sonocbemical oxidation of Am(III> by O^ and XeO. in HC10., 3 HNO., H2SO. (0.01-1 mol/dm ) and concentrated b\P0. have been unsuccessful. 2- The addition of Mn04" and Or^Oy for distraction of Hg02, formed by sonoly- se of water, doea not contribute to this process either. These facts can be connected with high oxidation ability of Am(IV) in acidic media and rapid re ducing of Am(IV) by eonolyee distraction components. The influence of ultrasonic vibrations for reduction of Pu(IV) by N?H. in HNO- and HC1 media at 18-20°C has been also investigated. It has been found that the rate of these processea increases in 10 times and equals to the first order by plutonium and M9H4 and -1 by H+ concentration* Thus the observed facts show, that under the ultrasound influence the behaviour of ectinide ions differs considerably from their behaviour under normal conditions! 359 THE REDUCTION REACTION OP NEPTUNIUM AND PLUTONIUM IONS 5-78] IN THE PRESENCE OP SOLID PHASE CATALYSTS '—" ' I.G.Tananaev, V.P.Shilov, N.N.Krot. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR The given communication reports the results of the studies of the inter action of neptunium (VI), (V) and plutonium (IV) with hydrazine in nitric acid medium in the preaenoe of solid phase catalysta. Dispersed metallic platinum and ruthenium deposited on an inert carrier were used as catalysts» In nitric acid eolrfcions, containing 1-100 mmol/1 of hydrazine at 15-25°С neptunium is known +J be slowly reduced to the pentavalent state. The intro duction to the solution of platinum on silica gel considerably accelerates the process. Neptunium (V) in similar media reacte with excess hydrazine only at temperatures above 70eC. The presence of the catalyst decreases the tempera pe rat u re to 30-40°C. Other conditions being equal, the catalytic reaction rate increases linearly with the increased concentration of the acid. The catalytic reduction of neptunium (V) is accompanied by the parallel oxida tion of neptunium (IV) by nitric acid. Increasing the concentration of nitric acid up to 4-6 mol/1 prevents the catalytic oxidation of neptunium (IV). The reduction of plutonium (IV) by hydrazine is also accelerated when using silica-base platinum and silica-base ruthenium catalysts. Increasing the content of the acid does not influence the reaction rate in the case of the platinum catalyst» and hinders it in the presence of the ruthenium catalyst. Data on the catalytic reduction of neptunium and plutonium by the reducers other than hydrazine in various systems are reported. Mechanisms suggesting the sorption of one of the reacting particles on the catalysts surface, have been considered. 360 FLOW-THROUGH ELECTROCHEMICAL REDUCTION OP URASIUM IN WET PROCESS 5_?g PHOSPHORIC ACID I—_ V.N.Kosyakov, P.E.Piskarev, Kurchatov Institute of Atomic Energy, Moscow, USSR A.A.Kist, I.I.Orestova. Institute of Huclear Physios of the UzbekSSR Academy of Sciences, Tashkent, USSR Phosphorites being main saw materials for produotion of phosphoric ferti lisers contain comparatively much uranium (up to 20bg/t). It follows from the analysis of uranium distribution in the technological chain of this pro duotion that In the dlhydrate proooss more than 9556 of uranium goes into wet process phosphoric acid (WfrA) and then Into the end product - amophoe. It is no osinoldenoe that more than 20 countries have developed the national programs on organization of the uranium recovery parallel to pro cessing of phosphorites [1] . For an average uranium content of phosphori tes equal to 50 g/t the realization of such a program at all phosphorites processing plants In the USSR could give to the country tens thousands tons of uranium per year. Though the ourrent teohnology of the uranium recovery from phosphorites being processed Is relatively expensive (122-24 per kg OjOg at plants with an annual output of SOO.OOOt PgO- [1] ). However, i t only economic t but also ecological reasons should be taken into considerati on. The use of phosphoric fertilisers unpurified from uranium leads to conta mination of soil with radionuclides, such as «4 232Thi 226Rei to an inc reased level of radioactive background and, ultimately, to accumulation of these radionuclides in the ecological chain: soil-orops-aan. All available processes of uranium recovery from WPPA oan be divided into two categories. Xn one oategory uranium is recovered in the hexavalent state and its comple te reoovery involves a stage of additional oxidation. Prereduction is nee ded for the processes of the second oategory where uranium is recovered in the tetravalent state, majority of the methods recently developed refer to the second category, as the recovery teohniquee (both extraction and sorp tion) used in this oase have an essentially higher efficiency [2] . uranium is reduced to the tetravalent state usually by introduction of powdery me tallic Iron (about 8g/l) Into SPA 13] , thus causing an additional contami nation of the fertilisers. To obtain the tetravalent uranium in ИА we used the electrochemical me thod allowing the quantitative reduction of uranium under flow-through con ditions. The reduction was made In a flow-through three-compartment eleat- rolyser, the cathode and anode spaces of which were separated by an ion-ex change membrane. Carbon fibrous material (CM) with a nonwoven structure filling the whole volume of the working zone was used as a working electro de. A spiral made of platinum wire served as a oounter eleotrodo. The volt- smmetrlo dependences of the 00?*—*ip* transition In WFPA were taken. The oondltlon of eleotroohemloal reduction were, chosen on their basis. Фае dependences of the 0** yield on the working eleotrode potential were obtained in the range of -0.7 to +0.25V at a solution flow rate of Iml/min per cm of the CBf overall surface and on the flow rate of WPPA in 361 in the range of 0.2 to 40 ml/Onin.om )• The degree of uranium reduction was determined spectrophotometrlcally from the oharaoterletio absorption peaks of D(IV) and U ID 20 v/a^elength. nm Absorption Spectrum of Uranium in WPPA before (1) and after (2) Electrolyses References l.Efimova Z.I., Smirnov Yu.V. et al.// Atom.Takhnika га rubezhom. 1985. H 10, s. 3-10. S.Efimova Z.I.. Smimov YU.v.,Sokolova I.D.//Atom. Takhnika га rubezhom. 1987. H 4. s. 3-10. 3.Deleon A., Lazareric M.//Proc.of Sao Paulo Symp. The Recovery of Uranium. IABA. Vienna. 1971. P. 351-362. 362 FLOW ELECTROLYSIS TECHNIQUE FOB PRODUCTION AKD STABILIZATION 5-80 OF BEPTUHIW ADD PLUTOHIUM IB СВЙ1АШ OIIDAMOH STATES V.N.Kosyakov, N.G.Xakovlev, ll.ll.Vlasov. F.B.Pisksrev. Kurchatov Institute of Atomic Energy, aosoow, USSR The electrochemical processes sufficiently recognized in the technology of irradiated nuclear fuel reprocessing oan prove also to Ъе very useful in solving any other problems, both fundamental and applied, ia chemistry of ac> tlnides «here stabilisation of the elements oxidized to a certain valent state is required. This work concerns some issues of electrochemical produc tion and stabilization of various oxidation states of neptunium and Plutoni um In nitric aoid solutions under stationery end flow-through conditions as well as investigates the examples of applying suoh a technique to the extra ction chromatography. The apace electrode is considered to be most suitable to realise the re duction-oxidation reaction in solution flow. For thle purpose we used colum nar porous electrodes made of carbon fibrous material (CSV). The cells were designed like those described earlier [l] . The working electrode was sta cked of Э-шт-thick pellets out out of nonwoven CPU (suoh as felt). The volume of the working section separated, as a rule, with a diaphragm was 0.25 to 0.5 ml. The use of GfH in the oolumnar electrodes has two evident advantages over other materials. Firstly, due to small size of the solution-filled ca vities in the electrode volume diffusion effects are essentially absent and suoh a oell works as a "space" thin-layer cell* Seoondly, the great specifio surface of the material allows« if necessary, a considerable amount of ex- tractsnt to be easily retained and oan be a good electrically conduotlve oarrler for the extraction chromatography. Voltammetry with suoh volume CPU eleotrodes makes It possible to obtain the information about formal potentials and kinetics of reduction-oxidation transitions of neptunium and plutonium. The potentials were Investigated in the range from - 0.2 to 1.5 V (SHE). 1 mol/1 - nitric aold was used. It was found for neptunium that every degree of oxidation from +3 to +6 can be ob tained If we start from HpoJ or Hpo|t Once all neptunium has been converted into Jfp4* (or Bp3+), it takes a long time to produce SpOg or HpO?+ even at E • 1.5 V. The rates of the reversible Нр4+/Нр3+ and Spo|+/NpO| transi tions are great enough to easily realize these transitions under flow con ditions. In the case of plutonium only the Pu4+/Pu3+ transition is easily and revereibly realized, if we start from Pu . The feed rate of solutions under flow conditions was varied from 0.2 to 5 ml/Gnin.cm2). Hpo|* and Hp4+ oan be easily produced and stabilized in ca se of proceeding from HpoJ. The SpOg range covers the values of potentials from 0.2 to 1.2 V. All neptunium turns Into Hpo|* at E > 1.3 V and Into Hp4+ at S < -0.2V. The reoxldation of Hp4+ under flow conditions tailed. Production of sir* is diffioult beoause of its spontaneous oxidation. Reali zation of the reversible Pu4+/Fu3* transition in flow does not present a problem, other transitions ere absent. за Separation of Sp(V) and Fu(IV) «Ш •№ by th« extraotlon-chroinatagraphic method. CIH coated with dl-S-ethgrlnexyl phosphoric «old (HBBHP) with CHt HCSHP • 10i1 by weight was used as a sorbent. Sorption of neptunium and Plu tonium from 1 aol/1 НЯ03 was investigated a* a funotion of the potential applied to the aorbent. ом starting solution contained IP and la In the form of HpOj and Pu**. the resulta are shown la Pig. Su(XV) and Bp(VI) are •orbed on the oolumn, Pu(III) and Bp(V) remain In filtrate. Jig. Sorption of neptunium and Sorbtlon, Plutonium In the oolumn with СИ : HDEHF. • 10t1 from 1 mol/1 HIQj aa a funotion of the oarrl- er potential* The starting ata- te«, apoi and So** 0.4 0.8 1.2 E, V(HHB) The optimal Talus for the potential to separate яр and Pu is E . O.BV (HUE). After passing 3 ml of the starting solution of the both elements through the ooltam and washing it with 1 mol/1 ГОТО, О ml) at 8 • 0.8 У the potential waa deoreaaed to Б - 0.0У and plutonlum was eluated with 5 ml of 1 mol/1 HBOj. The degree of purifioatian of Hp from Pu emounte to 35, the yield of ар being 98*. She alallar values for purification of Pu from Hp equal to 10* and 70* respectively» Separation of Pu(IV) and Om(III) waa performed on ОРИ modified with tri- oetylphosphlne oxide (TuPO) at a weight ratio of CPU» TOPO - 100i1. The ata rtlng solution of the both elements In 1 mol/1 no, was passed thBough the oolumn at В « 0.9 Т. After washing ths reducing elution of plutonlum waa made with 5 ml of 1 mol/1 НТО* at a potential of 0.0V. The degree of puri fication of plutonlua from ourium waa better than 10, the yield of Pluto nium being 85*. Reference 1. Koejrakov V.B., Vekovlev H.O., Пакт М.М.АпШ оИНаяув. 1986. Т. 28, В 4. S.547. 364 ELECTROCHEMICAL REDUCTION OP ACTIKIDE IONS TO AMALGAMS IN J I AQUEOUS SOLUTION ABD SOME EXAMPLES OF ITS APPLICATION I I P.David. Institut de Physique Nucleaire, 914-06 Orsay^ France A.G.Uaalennilcov, V.F.Peretrukhin. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moaoow, USSH Electrochemical reauctlon of heavy elements from aqueous solution to amalgams was studied by radiopolarogrephy and radiocoulometry methods• Mechanism of actinide reduction on a mercury pool is discussed through simulation technics. Special emphasis is pointed out to redox reactions and potentials, kinetics of the process and effect of acetate and ci- tiate ions as complexing agents* Three groups of actinides have been found out. The first group represents actinium and from uranium to her- kelium. Reduction ocoure in the experimental conditions via an irrever sible 3-0 process* Xhe second group oenaists of the elements from fer- raium to no be Hum» which are reduced in non completing solutions, or with acetate lone, similarly as barium and radium via a reversible 2-0 reaction. Finally» californium and einsteinium behave as intermediate elements. It is noticeable that such groups are also observed In the actinide series by studying tbe structure of the trivalent aqua ions. On tbe basis of the above mentioned investigations of actinidee and lenthanidea several examples of electrochemical application are presented* Californium has been separated from precedent transuranium and lanthanides (except europium) by elecroohemical reduction to amal gams la aeedic solution* Separation f~u±ors from 25-90 are achieved with appropriate cathodic potentials* Similarly, this element could be separated from several heavier aotinidea with oitrio media* Tbe electrochemical preparation of mixed uranium-nickel and ura nium-tin amalgams from aqueous acetate solutions is Investigated. The dependence of redox potentials of mixed amalgams on different atomic ratio UtHi and U:Sn in amalgams is measured. The big shift of redox potential of mixed amalgams to tbe positive direotlon is detected when the atomic ratio UsNi or UtSn in amalgams reaches 1:5* The ther mic distillation of mercury from mixed amalgams with different atomic ratios UiNi and U:Sn is carried out and the products are Identified by chemical analysis and X-ray diffraction* The intermetallies UMie and USn~ are prepared from mixed amalgems with the atomic ratio rJiHi- 1:5 and U:Sn- 1*3- The uranium and neptunium amalgams are prepared by electrolysis of aqueous acetate solutions and are processed into metals or nit rides UgN,, HpH by thertnic distillation of mercury in vacuum or in nitrogen atmosphere* 365 OXIDATION OP AHERrCIUH(III) IN SOLUTIOTS OF OOHBBNSED 5-82 PHOSPHATES T.I.Trofimov, Yu.M.Kulyato, I.A.Leoeaov. Vernadsky Institute of Geochemistry and Analytical Chemistry of the Academy of Soienees of the USSR, Moscow,USSR Separation and determination of transpluionium alements(TPB) based on methods using their "unusual oxidation states" are known to Ъе the most effective. Some of the TPBs in unusual oxidation states are generated and stabilized in various madia such as solutions of alkali motal carbonates Л7. aqueous and aeetonitrilio solutions of phosphoric acid 12-47» phospho- tungstate solutions Z3-67, etc. Therefore, there has been a continued search for new media in which suoh oxidation states of TPEa would be obtained and stabilized. It has been reported that the TPE amerioium(IV) can be stabiliz ed by dissolving Att(OH). in solutions of potassium pyrophosphate, one of the condensed phosphates, in presence of ammonium fluoride /3?. However, there has been no report on studies on direot oxidation of amerlcium(III) In so lutions of various condensed phosphates. The present investigations show that solutions of condensed phosphates provide suitable media for such pur poses. The present work has been devoted to investigations on electroohemical ^_ and ohemieol oxidation of americium(III) in aqueous solutions of pyro-tPgO- ) tripoly-CP.O-jjJ), trimeta- The chemical oxidation of Am(III) by Na^Og, Ha.XeOg'B HjO, K,Fe(CN)£ and H,0„ in solutions of condensed phosphates naff been studied at various pH (1-13) of solutions. The result of oxidation has been found to depend 366 upon pH of solution, nature of condensed phosphate and oxidant, and ratio of concentration of ameriolun to oondensed phosphate. Thus conditions of ob taining Am(VI), Am(V) and Am(IV) In the oondensed phosphate media have been established. References 1» Hobart D. E., Samhoun K., Peterson J-K. // Badloehlm. Acta. 1982. Vol. 31» К 314. P. 139-145. 2. Xanir E., Given И., Harouo J. // Inorg. Ifuol. Chen. Lett. 1969. Vol. 5. P. 369-372. 3. Цгаеоеоот B.F., Lebedev I.A.,,Mikhailov V.M. // Dokl. Aked. №uk. SS3R. 1973. Vol. 211. P. 1Э51-1Э53'. 4. Kulyako Yu.K., Pejevalov S.A., ^renkel V.Xa.• Lebedev I.A., Hyasoedov, КЫайпуак P.L. // Radioehem. Sadioanal. Lett. 19B3. Vol. $9. P. 235-244. 5. Saprykln A.S., Spltsyn V.I., Krot H.H. // Dokl. Akad. Sauk. S33R. 1976. Voll 226. P. 853-856. 6. Kulyako Zu.U., Leoadev I.Ai,, Srenkel V.Ya., Xroflmov T.I., IQraaoedov B.?. // Radlokhimiya. 1981. Vol. 23. P. 1*37-843. 367 USE 0? THIN-LAYER CHROMATOGRAPHY METHOD FOR ПЖКТ1Р1САТ10Н OP 5-83 AHERICIUM IN VARIOUS OXIDATION STATES N.P.Holoohnikova, Т. V.Dubrova,NLP.Volynets. Veraadsky Institute of Geochemistry and Analytical Chemistry ,of the Academy of Scienees of the USSR, Moscow, USSR Thin-layer chromatography (TLC) using for the isolation and separation of traoe elements is a perspective method for radiochemical studies including various ionic forms of elements coexisting in the solution. The advantages of TLC (simplicity and rapidity of the separation, the high relation In combina tion with high-sensitive radiometric and autoradiographic detection methods, etc.) make it effective for investigation of trace transplutonium elements behaviour in various oxidation states. Sarlier /1,3/ TLC was used for quan titative separation of Pu(IV), (VI) from Pu(III) and U(VI) from Pu(IV) and Am(IIX). The chromatographic behaviour of amerioium in the highor oxidation states during TLC had not been investigated previously. All chromatographic developments were carried out on silioa gel commerci ally codted TLC plates "Silufol" (Czechoslovakia) by ascending technique. The optimal conditions were obtained for the extraction isolation of americium in various oxidation states by the isobutanol solution of 1 -phenyl-3-methyl-4- benzoylpyrazolone-5 (PHBP) earlier /3.4/. Therefore, this organic solution was used as a mobile phase. The procedure of obtaining of americium in the highar oxidation states was published /4/- The chromatographic mobility of americium was investigated in the dependen ce on concentration of nitric acid solutions, oxidant /ammonium persulfi.te) and complexlng agent (potassium phosphotungstate) (Pff)- It is <&own that ame- ricium(III) L-ovee with mobile phase front from 0.1 - 0.001 и НПО, but the ac- tinides in the oxidation state +5, inoluding americium(V), remain on the start in these conditions. That allows to separate these elements (Pig. 1}. The be % haviour of amerlcium(VI) is similar to to* AmIVI this of amerlciun(V) and differs from the Amtvi} WD, distribution of uranium(VI) moving with mobile phase (Fig* 1, годе 5). That allows to suggest that ooerioium(VI) is reduced PaM to the more stable amerioium(V) in these /torn conditions. On the basis of the data ob tained the conditions for separation of amerlcium(V) and (VI) from the trivalent aetinidea, europium and uranium from nit rate solutions con be found (Fig. 1). It is possible to separate saeriolua- 243 from its daughter product naptunium- 239 in these conditions. Pig. 2 shows the 368 see from the data obtained there is pure neptunlum-239 in the spectrum of the original none. Americlua(III) la located sear the start in the presence of ammonium psr- aulfate, that's why the Identification of enorleium oxidation state by TLC in nitrate solutions is possible only using the electroohemloal oxidation of aaerloiuiB. the separation of aaerlciua in various oxidation states takes pla- ee in acetate solutions at pH «.5 - 5.0 in the presence of oomploxlng agent - potassium phosphotungstate. imerioium(III) and (IV) remain quantitatively on the start in these conditions, compared to americiuu(V) and (VI) moving with the mobile phase front (Pig. 2). Cranium(VI) moves also with organic phase, It makes possible to separate trl- and tetravalent actinldee from penta- and hexavalent elements* Thus» the method of thin-layer chromatography can be used for isolation of americlum in various oxidation states and for separation of amerieium(V} and :VI) i'rom other aotinides. *%« 250 Euttlll AnU) Amlm £150 Ьф1) 50 • Ч 'Ь Ь I < I 5 || 100 150 100 150 start m. ph. front Channel number zones of TLO plate Pig. 2. Referenoes 1. Valjmcts II. P. Ouseva L.I.//2h. Analit. Xhlq. 1968. 1.23. S.947. 2. Volynets H.P. Hilyukova H.S.//Radiokhii»iya. 1971. 1.13. S.72. 3. Myasoedov Б.Р. Xoloehnikova S. P.//Eadlocbem. Radloanal. Lett. 1974. i.ia. s.33. 4. Holoehnlkova If.P., Fretful V.J л., Myasoedov B.P. et al.//Radlokhlmlya. 1982. T.24. 3.303. Z4.3an.I607 369 KINETICS ASPECTS OF ACTIHIDB EXTRACTION AND SEPARATION IN 5-84 EXTRACTIOB PROCESS V.S.Koltunov. A17-.Union Research Institute of Inorganic Materials, Moscow, USSR The modern methods of nuolear fuel reprocessing are baaed on extraction processes using oxidatlon-reuuotion reactions to stabilize Pu and Np in the required oxidation states. In this connection the successful distinct sepa ration of U, Pu and Np is mainly determined by the rate and completeness of these reactions. The paper discusses the kinetic and thermodynamic data on the indicated reactions ав applied to the principal operations of the extrac tion process. Prior to the first extraction cycle the sutoatabllizatlen of the Pu(IV)- Bp(TI) valence pair with nitrous acid resulting from HBO, radialysis sea a disadvantage as Hp is ohlefly stabilized In the pentavalent state, and its transfer to the organic phase is determined by the reaction rate of the slow Hp(T) oxidation with nitrate ions. This disadvantage is eliminated when V(V) ions are added to the solution as In this case all the forms of Pu and lip qulokly oonvert to Pu(IV) and Up(VI), respectively.The paper discusses the kinetics data on reactions of Pu and Kp ions with V(V) sad V(IV) lone. The use of hydrazine and particularly some of its organic derivatives to prepare the Pu(III)-Np(V) pair during reducing re-extraction has some advan tages over Pe(II) and U(IV); the principal one is the non-salt forming nature of these reducing agents and the distinct stabilization of the indicated ion pair. Consideration is also given to the: attributes of the usage of hydroxyl- amlne and aseorblo acid to re-extract Pit and Np. The paper dieeueaes the in fluence of Tc ions on *4e oxidation-reduction reactions of U, Pu and Kp. The full kinetic data are given for all the reactions considered. Affinage operations the aim of which Is to separate Pu and Np and to ulti mately purify from fission produots are based on oxidation-reduction reacti ons resulting in the stabilization of Pu(III)-Hp(IT), PuCIY)-Np(IV) and PudV)-Np(VI) ion pairs. Consideration is given to the peculiar kinetics of these reactions and the optimized conditions of the stabilization of the in dicated ion pairs. 370 KINETICS Of CUBIOU MB EUHOPIDH ИМНАСТ10И BIIH 2-ВТНЗаНЕШДаЕ1НЬ PHOSSHONXC ACID IN CENTRIFUGAL EXTRACTOR [TeT] G.I.Kusnetsov, F.2>.Kasiinov, A.A.PushkoV, V.A.Beaepov. Mendeleev Institute of Chemical Technology, Moscow, USSR Cne of the most perspective type of equipment for transplutonium elements extraction from high level radioactive solutions ie a centrifugal extractor. The centrifugel extractor for radiochemical processes ECR-33 (pig.1), has been developed the base designs [1], Feed solutions are fed through pipes 1 to a labyrinth mixer-blower 2 and forced into a nrimng chamber 3. Emultion is fed to rotor 4» «here it is divided under the action of centri fugal forces. The oivided liquids are directed into circular collectors of a fixed body 5, then they gravitate from the extractor. Rotor unit 4 with dri ve в is remotely replaced by a reserve one. The extractor has following technical characteristics: capacity - up to 0,007 1/sec, rotor diameter- 33 mm, operational rotor s volume - 0.021 1, drive power - 0.04 кв, length* ^°- - width«height (together with eleotrio motor) - ) 7 90 mm * 105 mm * 320 mm, mass - 5.8 kg. Operation "fr al volume of the пИтчт,е chamber is 0.025 It that 1 provides the contact time between phases 3,6 sec. в The «<^ис chamber volume may be enlarged more than ten times for processes with slow rate or may y&Sd i_j be reduced for fast proonsses [2] , з*ч5ш5!Э?я To calculate the optimal regimes of the process it is necessary to know the'masstransfer kinotios of the different elements in the centrifugal ex tractors. Kinetics of Cm and Eu extraction with 2-EHPPA in centrifugal extractor was studied in accordance with the prescription [З]. Curium had 2 2 the following isotopic composition! Cm * -23-2S, M.g.1. Centrifugal CmZ4*-75.3». Am241-1.5SS and Eu had 20* of Eu15* extractor and 80? of Eu'J-'. The rate of extraction and stripping of Cm and Eu with 2-EHW?A In Di-КГШП. ВИВОЬ (ВВВ) under the intensive mixing of liquids in the centrifugal extractor is rather high (Pig.2), and depends on the rotor speed (n) and volumetric flow rate ratio of organic to water phases («£ ). The dependence of the masstransfar efficiency (E) on the contact time ( V ) In the mixing chamber is being described satisfactorily by the equation of the full mixing model in two phases: S • 1 + 1 1 +€ К • P 'V where i. - extraction coefficient; V - organic phase volume; \, - mass- transfer coefficient, calculated through the phase у; Р - Interphase surface. Thus, In the Investigated conditions Cm and Eu extraction kinetics is determined by the diffusion processes efficiency of whloh depends on the 371 mixing intensity and phases flow rate ratio in ite turn effecting the value of the interphase surface (P). the fact that -these processes proceed in the diffusion field has been additionally conformed by independence of the rate from temperature (f-s 5 - 45°0) and nitric acid concentration (see Pig.2). Pig.2. Dependence of Cm and Ea extraction and stripping efficiency (B) from the time (t) of phases contact in centrifugal extractor. The systems З'Ю-8)! Си, 7О0"8» Eu in HMO, - 0-5И 2-ШРРА in BEB. _1 1 a)e - Ош;0.эН HS03;«t»0.65i n»25a h)e - Сщ;2И fflTOy.l-5.4t n-SOs" 1 1 О - Ви;0.6И НМ03;Л.0.65; n»25s" О - Euj4H HH03J«t-5.4j n-50s" 1 1 •J- Cm;0.2~1H HN0.i4-o.65; n-50s~ • - Cm;1-2H ШК>35-г-»0.65> n»50s~ 1 _1 П- Еи»0.6-2И HH0jj.t-O.65i ПР50В" • - Eu|2-4l! HH03Joi«0.65; n»50e References I.Kuznetbov a,I., Pusbkor A.A., Belyakov S.M//Att>mnaya Bnergia. 1986.Vol.61.P.23. 2.Kuznetsov 6.1., Belyafcov 8.U., Shklyar 1.Д., PuehkOT ii.Xj/^SC-SO, Vol.1. Liege, Belgium. J.SchepetiluUcoT H.M., KusnetBov G.I., Pushlenkov K.S.t Yakovlev G.M.# Eadioenemistry.1972. Vol.14. P.345- 372 KINETICS OF AQHBXDB VALEHCY THANSFOBMATIOT ЦГ ALPHA-RADIOLYSIS 5-66 OF NITRATE- ADD PERCHLORATE SOLUTIONS A.A.Prolov, N.N.Andreychuk, X.v.Rotmanov, L.M.Frolova, V.Ya.Vasil'ev. Lenin Research Institute of Atomic Reactors,Dimltrovgrad, USSR This paper presents the results of the systematic studied kinetics of valency transformation of uranium, neptunium/ plutonium, americium, berke- Lium in nitrate-and perchlorate solutions under the effect of the inten- 244 ive internal alpha-radiation emitted by Cm nuclides.The high dose rate i solutions (D=1-8Gy/s) provided the sufficient yield of H-O-» HN02 and СЮ3- the main products of the alpha-radiolysis of water, nitrate-and perchlorate ions, respectively- that allowed to be determined by the spectrophotometry methods immediately in the course of the process under study. As the performed studies established the actinide behavior dependences on the experimental conditions as well as on the nature of actinide itself. Thus the oxidation processes are observed in uranium-contained solutions [XJ and the reduction processes are noted in americium-or berkelium-con- tained solutions £Q, These processes all proceed to completion and only one valency form of the elements mentioned presents in the equilibrated solutions.On the other hand both the oxidation and reduction processes were observed in neptunium Qttf- or Plutonium /S,57-contained solutions resulting in equilibrium among the various valency forms of the elements mentioned. The equilibrated state of these systems is independent of the starting actinide valency form. Hot only the studied actlnides all differ .',n direction and equilib rium state of the process but in effect of 'the kinetic curves observed and time of their completion.Thus at the same experimental conditions (CHKO =1 mo1'1' ^*3Gy/s) in systems with starting Pu and hours but in systems with starting Np(IVrV,VI>, Pu(IVrVI) and Am(V) £1-57 *^е Process is over in tens, hundreds and even thousands of hours. The kinetic dependence of the recent processes are of complex nature due to the availability of minimums-maximume on the curves of Up (V)-and Np(VT)-changed concentrations /37, the appearance of Inductive periods and following autocatalysis process (in case of pu(HI) and Pu(VI) £$,Zf)w the transformation of the law of rate with changing the dose rate and solution composition (especially In the case of Am(V) /k7- Thc analysis of the obtained data £T-6/ shows that elevation of the initial rate fvQ, with increasing the dose rate Is a total feature for all actinldes and depending on the- solution composi Hw and cl0 fonaed tion the change of v is similar to that of B2°2' °2 2 yields. The kinetics of the actinide radiation transformations In nitrate- and perchlorate solutions is affected by the radiolysis products as evidenced by all the above mentioned. To describe the obtained results the kinetic scheme considering the effect of the dose rate and changed solution composition is suggested. In each separate case the constant rate values of single reactions included in the scheme are estimated. The kinetics of the radiation transformations in the alpha-radiolysis of nitrate-and perchlorate solutions has been carried out by the special programmes £)r87 on theE3CM-6 computer. The examples of these calculations are shown in „3,97, References 1. Andreychuk H.H., Frolov A. A., Vasil'ev B.Ya.//Radiokhimiya. 1987- T.29. S.417-421. 8. Prolov A.A., Prolova b.M., Vaail'ev V.Ya.//Ibid. S.79-87. 3. Prolova L.H., Frolov A.A., Vasil'ev ir.YB.//Ibid. 1984. T.26. S.108-114. 4. Vesil'ev V.Ya., Andreychuk H.H., Proiova L.M. et al.//Ibid. 1985. S.327- 336. 5. Andreyenuk N.N., Rotmanov K.V., Prolov A.A., Vasil'ev V.ia.//Ibid. 1987. T.29. S.412-417. 6. Prolov A.A.Chistyakov V.M., Kornllov A.S., Vaail'ev V.ia.//Ibid. )og5. S.59-64. 7. Abramenkov A.V., Abramenkov* I.A.//Khlmiya vyaoklkh energy. 1979. T.13. С 557. 8. Bugaenl» V.L., Griahkin V.L. Paket programm dlya modellrovaniya proces ses khimlcheBkoi kinetikl. U.: Preprint ITEF, 1980. Я 54. 40 a. 9. Prolov A.A., Andreychuk N.H., Rotmanov K.V. et al.//III Vsesoyua.oonf. no khimii TPE. Dimitrovgrad, 1988. Tez.dokl. X., 1988. S.68-69. 374 KINETICS AND THERMODYNAMICS OF TETRAVALENT Aia,Cm,Cf IONS REDUCTION! _ I TH POTASSIUM PHOSPHOTUNGSTATE SOLUTIONS '— ' G.A.Timofeev, E.A.Erin, V.M.Chistyakov, A.A.Baranov, p.N.Karbovnichy, V.v.Kcpytov , Lenin Research Institute of Atomic Reactors, Dimitrovgrad, USSR Stabilization and investigation of actinides,in particular, of cm and Cx. in highest valency states are an important problem of modern radio- chemistry. First investigations on stability of cm and C£ ions with oxidation state +4 in a potassium phosphotungstate solution were carried out in the presence of an oxidant - S20Q ions and their decomposition products. Cm(IV) and Cf(IV) reduction was supposed to be due to radiolysis and reaction of interaction of these ions with water. In the present work there axe given the investigation results of tetra- valent Am,cm,cf(Me(lV)J ions behaviour in KPW solutions that do not con tain an oxidant. The experiments were performed with isotopically pure +7,14 24 Cm + o,o3% 244cm and 99,4% 243Am + o,6% 241Am. Actinides with oxidation state +4 were prepared by dissolving the double complex phospho- tungstate salt He(IV) with Cs in a fresh portion of potassium phospho tungstate. Spectre-photometric investigations showed that in all cases reduction of Me(iV)into Metlll) was observed- The rate law is the follow ing: StelivV dt ~ Xo + k1 * *Т1е(1У) The analysis of kinetic curves allowed to define the values of effec- tive k. and к rate constants for various experimental conditions. The increase of doze rate for internal solution «с-irradiation causes the increase of the k0 rate constant value. This demonstrates that Me(iv) re duction according to zero order reaction in KPW solutions is mainly due to radiolytic processes taking place in the solution. It is also indicated by practical stability of kQ with changing KPW concentration. At the same time there is no correlation between k1 values and doze rate of internal solution et-lrradiation which gives evidence in favour of chemical nature of Me(IV) reduction process according to the first order reaction. Within ;he whole studied pH (1-6.5) values interval the reduction rate of Me(iv) ions by this way increases in Am-Cm-Cf row. on the other hand,the k.,~pH ratio is of extreme character with minimum shift into alkaline region while transfering from Am to cf that might indicate the stability decrease of complex He(IV) Ion forms resulting from protonization process.Besides, 375 S2£: it should be noted that the reduction rate of Cm(IV) and Cf(IV) according to the first order reaction grouswith the KPW concentration increase when the reduction rate of Am(IV) falls. The reasons for such difference in these ions behaviour are still not clear. Study of temperature effects on the reduction rate of Me(IV) ions made it possible to calculate the thermodynamic activation parameters of Me(IV) ions reduction reaction by the chemical way (Table)» it is obvious that stability of the activated complex formed by Me(IV) ions under the studied conditions decreases in Am-Cm-Cf row.This decrease is generally connected with the entropy change. -3 pH 3,0; CKpw=6,V10 mol/l Am Cm Cf AG299^ , kJ/raol 92.1 79.9 71 .9 iH i- , kJ/mol -59*> 60.3 58.2 1 »S r , J/K-mol -(104-113)*) -67 -46 *) - evaluation •••Ч- KINETIC ISOTOPE EFFECTS IN THE REACTIONS OP ACTINIDES Г£5Г1 S.I» Nikitenko. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR The influence of the complexation of Pu (IV) and Pu(III) with nitrate-,chlo- ride- end sulphate ions on the rate of the isotope exchange (IE) between Pu(IV) and Fu(III) has been studied by the method of oi -spectrometry. It has been shown, that during the increase of concentration of NO,~ or CI*" the IE rate > 2- uecreases and in the sulphate .media the rate dependenoe on SO. is described by the curve with minimum. It is assumed* that in accordance with the Frunk- Condon principle in chloride and nitrate media the exchange proceeds between aqua ions of Pu(III) and Pu(IV). In sulphate solutions, together with aqua ions» their monoaulphate complexes take part in the exchange process. Kinetics of IE between five and six valent actinides has been studied on the example of reaction between Np(V) and Np(VI) in the presence of oxalate. It has + been found, that the exchange process between bis-oxalate complexes of Np0o and NpOg proceeds much slower than between aqua-ions. In a number of cases the formation of the weak diaaocoative complexes brings to practically full exclusion of the isotope exchange. Thus, the rate of the IE reaction between 17- Am(P2Wl706l)2 and AmL~, where H4L a EDTA, is rather small in comparison with the rate of Uganda exchange between Am(P2W1„0^1)_ '" and H.L~. Besides the Investigation in homogeneous media, the kinetics of IE between Pu(III) and Pu(IV) has been also studied in nitrate solutions in the presence of anionite VP-1AP» TBP in a polymer matrix (TVEX) and also ТБР and TTA, co vering the surface of the hydrophobizad silica gel. It has been shown that in the system with TVEX the IE rate is determined by diffusion inside the particles of a solid phase, and in other ayeterns the exchange process in-the solution represents a limiting stage. To study the isotope effects in the reactions of actinldes mass-, el and Y -spectrometry has been used. It was found theft for the mixture of " Pu and 4 Pu, in the disproportions- tlon reactions of Pu(V) the non-reacting part is enriched by light isotope; moreover, the value of the elementary coefficient of isotope separation ( oL ) for 242/238 Pu equalB to 1.023» To prevent the IE between Pu(V) and Pu(VI) and also for exclusion of the side redox-reaction between Pu(IV) and Pu{V) the process was performed in a colomn, filled with silica gel, covered by D2EGPA, Tbe part, containing Pu(V), was going along the colomn and the products of disproportionstion were extracted from tbe solution rather rapidly. Using the same principle kinetic isotope effects were studied in the oxi dation reaction of Pu(III) to Pu(IV) by a number of oxldiaers (nitric acid, persulphate and etc.). The kinetic isotope effect was found in the reaction of ligand exchange 17 243 241 between Am(PgW1706l )2 ~ and H^L. Tbe evaluation of aC fbr ' Am equalB to 1.025. 377 ISOTOPE EXCHANGE REACTION IH URANOUS-URAHYL- 5-Э9 SUUHURIC ACID SySTHS* Ling Daren, Yue Tingsheng, Hu Dehai and Wang Yanl. Department of Modern Physios, Lanzhou University, Lanzhou, China The kinetics of the electron exchange reaction between U(IV) and O(VT) hae been the subject of several investigations under a variety of experimen tal conditions* The reactions were studied in particular detail in hydro chloric acid medium /i-£7« The reaction in sulphuric acid medium are received only limited attention f€J* The present work was undertaken to find the ef fects of acidity, temperature and catalysts on the isotope exchange rate in uranoue-uranyl-eulpiiuxie acid system to maximise the lnorease of the rate of the Isotope exchange of U(IV)-U(VI) Ions. Reaction. Kinetic experiments were carried out In a darkened vessel hav ing purged with high purity nitrogen gas and thermoetated to 0.1°C at the desired temperature. Uranyl stock solutions were prepared by dissolving U.Og, which contained 3*06 and 0.46% 35U, respectively, In the appropriate amount of sulphuric aoid. The flash uranous sulphuric aoid solutions were prepared by electrochemical reduction. Effect of acidity on R. The leotope exchange rate wae calculated with Mckay's rate equation. The effect of acidity on R was studied over the range 0.07-0.5 M at 25+0.IеC. The results are presented in Tab. 1. The minimum of R appears at 0.25 M and the half-live t 1/2- corresponding to the acidity, is 58 mis t- /2 is 10.2 s when the acid concentration Is 0.5 M. A probable me onanism is suggested that two activated complexes might be presented in the reaction solution: the oxygen-bridge activated complexes occupy at first a dominant position but the stability of the species rapidly reduces with in creasing the acidity, at the same time, the activated complexes containing acidic radical increase as increasing of H„S04 concentration, so that the minimum appears at the plot of IgR via lg/ЙЛ Table 1. Effect of acidity on R H SO R D(IV) B(VI) 2 4 *1/2 10% 10% Ы (mole/s) min. 5.07 4.59 0.07 5.92-10"5 0.46 5.21 5.20 0.15 1.44MO"3 2.06 6 5.И 4.75 0.21 1.67-Ю" 17.0 5.21 5.20 0.25 5.20-10"7 57.7 5.17 4.36 0.29 2.73* 10"6 10.0 5.00 4.83 0.35 1.35- Ю'5 2.08 5-46 5.44 0.50 1.BV10"* 0.17 Effect of temperature on R, Prom the results of Tab. 2 the temperature enhancee from 20°C to 35°C,tbe half-live, t, .g, 60 tinea decreases. The spe cific veJ-jity constant, K, was calculated Ъу the expression: R • K/U(IV)7 /D(VI}7, and apparent active energy to be 86 kcal/mole. The high value of The project is supported by the aolence fund of the Chinese Academy of Sciences. 378 the Active energy shows that the activated complexes hardly form in the range of the acidity, which is Identical with that mentioned above. Table 2. Effect of temperature on R U(IV) UCVI) T R *1/2 10% 10% И К (mole/s) rain. 5.28 5.28 0.28 293 2.99.10"6 10. 1 4.36 5.17 0.29 298 2.73* Ю"6 10.0 5.12 5-41 0.25 303 1.79-Ю"5 1.66 4.46 4.97 0.26 308 i.49'10"5 0.18 Effect of catalysts on R. The effect of the catalyst Fe(Il) on R are chown in Гас. 3- The acceleration effect indicated by K/K can bring about 1000 times aa large an exchange rate as Is obtained without the presence of the accelerator when the Pe(II) concentration keeps 2-10*4 M. Thererfore, a probable mechanism* in which a middle act vat ed compound of U(V) may be form ed, for the acceleration action of the uranium isotope exchange by 7e(II/ at a constant concentration of eUlphuric acid is postulated.. Table 3. Effect of Pe(II) on isotope exchange of U(IV)-U(VI) (t*25±0.1*C) N /FeCII)/ /u(iv)7 /&CVI)/ К R K/K0 *V2 3 1.10"2 5.24 4.95 6.5-Ю*2 1.70.10"6 0.66 1038 4 !'10"3 5.43 5.12 1.2.10"1 3.29-Ю"6 1.2 540 11 5-10"* 5.25 5.41 3.6.101 1.04-10"3 366 1.7 6,10,14 2-10-4 5.26 5.06 9.6.101 2.55-10"3 980 0.7 12 5-10"5 5.25 5.21 4.7-101 1.3O-10"3 480 1.4 8 0 5.25 4.94 9.8-10"2 2.55-10"4 1 698 When the uranium Isotopes are enriched Ъу ion exchange, singer separation factor could be 1.001,thus) the half-live t1 ,2 should he leas than one second for the commercial application of the chemical method. 'Phis paper shows if the acidity and temperature of the system are resonably fitted, in addition, some catalysts are added to the system, an ion exchange system for the in* dustry application, which has a half-live leas than one second, should be established. References 1. Miyako Г. et al. // G.B. 2.053. 175A (1980). 2. Seko U. et al. // U.S. Pat. 4. 049. 769 (1977). 3. Kakihana H. et al* // Inter. Conf. Bud. Radioehem. China. 1986. P. 87. 4. Tomiyasu H. et al. // Bull. Chem. Soc. Jap. 1975. Vol. 48. P. 13. 5. Yang Enbo // Atom. Ener. Sci. Teohn. 1987. Vol. 3. P. 330. 6. Peckett J.W. // Radlochim. .Acta. 1975. Vol. 22. P. 106. Ф RADIAKOS СННПЗТНУ OP AOSIBIDES I , . i 5-90 M.V.Vlauimirova. All-Unlon Researoh Institute of Inorganic I Materials, Moscow, USSR Actinides, viz., neptunium, plutoniun, americium, curium, berkelium are valuable components of Irradiated nuclear materials. The extent of their extraction from an initial material end separation from each other and fiss ion products is an important problem. In practice the course of prooesses and actinide behaviour are strongly influenced by the ionizing radiation of the elements themselves and fission produota. To-day thanks to the efforts of different scientific groups a great body of experimental data on the radiation-chemical behaviour of II, Pu, Ир, Am and Bk in aqueous solutions Д/ as well as U, Np, Fu in organic extraction systems [г] have been obtained. Investigations perforated in the most extensi vely employed system 30% TBP+diluent show that the radiation-chemical beha viour of U(VI), Np(IV),Pu(IV) is defined by their interaction with IBF radio- lysis products, primarily, with di- and oiono-butylphosphoric acids. As a re sult complexes of several types are formed which at high irradiation doses (10° Gy) lead to precipitation. The radiation-chemical behaviour of Np, Fu, Am, Bk has been adequately studied in different aqueous solutions, nitric acid included. Ibis paper discusses the radiolysls of nitric acid solutions of actinldeB. Meptunium. During radiolysls Np(VI) is shown to reduce to Np(V), while Np(IV) oxidizes to Np(V). In HNO, solutions of the concentration more than 5 mole/1 due to HpCV) disproportionation three valencies of Np are always present in equilibrium. With the growth of ГштоЛ and dose rate (f) the equi librium concentrations of Np{VI) and Np(IV) increase and those of Slp(V) decrease. Plutonium. During radiolysls in 1-8 moWl НПО, Pu(VI) reduces to Pu(IV); the latter oxidizes to Pu(VI), Fu(VX) is observed to reduce at the concent ration more than 0.001-0.005 mole/1, at lower concentrations it is stable. The kinetic, dose curves of Pu(VI) reduction have an induction period which is the higher In the dose the higher is ПшоГ| and the doee rate. In pre sence of U(VI) and Hp(VI) the rate of PufVI) reduction increases. Pu(IV) oxidation in 1-8 mole/1 ЯИ0* is observed at its concentration less than 0.1 mole/1, at higher concentrations Pu(IV) is Table. The extent of the ra- diolytic reduction of Pu(VI) and oxidation of Pu(IV) depends оп[Ш»оЛ, fpu] and P. The higher are |"нН0-1 and P and the less is plutonium concentration the higher is the equilibrium concentration of Pu(Vl) and the leas is PuCIV). In preaence of uranium and neptunium the equilibrium concentration of PuCIV) increases. Amerlclum. In НПО, of the concentration less than 6 mole/1 the radiolytic reduction of Aa{V0 proceeds to Am(V), while in a more concentrated acid - to Am(III). The rate of Am(YI) - Am(V) reduction is considerably higher than the rate of Am(V)-Am(III) reduction. Berkelium. Under the action of radiation Bk(IV) reduces to Bk(III). The reduction rate depends on the berkelium concentration and the dose rate. 380 Reducing agents for PuCVI), Np(VI), Am(V.T) and Bk(IV) ere НПО,, ami H2°2' oxidizing agents for Np(IV) are HgOg and №. radicals, those for FuCIV) are NOj radicals. There is some progress in the theory of radiation prooeases in actinide solutions, particularly, in nitric acid solutions of plutonium. Work is beln? carried out on mathematical modelling [il* The model is a system of differen tial equations of the rates of formation and consumption of all the radio- lysis products (e", H, OH, KOj, JK>2, HK0g,Hz02) and Pu(III), lu(IV), Iu(V) and Fu(Vl) both in the absence and presence of U(VI). It is shown that In the absence and presence of uranium the rates of Pu(VI) reduction are descri bed by the expressions: _ _ _ 2 -djpu'vljj/at •= K^Pudlll ЦиОО] +K2jru(V)| - K3 |u(IV)l |H03J- 2 - K4pu(iv)T 2 -d[pu(vij]/dt = K^diiJ) [?u(vj] + K2[PU(VJ] + K5[PU(V7) (u(v5]- 8 - K^guCivgjsOj"]- K4j>u(ivf) The expressions for Pu(IV) oxidation rates are similar to those presented but have the opposite sign before the terms* It is shov/n that Pu(V) and FuClII) concentrations are determined by the rates of the reactions,- Pu(VI) + HM02, Pu(V) + M02, Pu(V) + NO , Eu HH02, Pu(IV) + Hg02, Su(III) + И0г, Pu(III) + H03; U(V) concentration is dictated by the rates of the reactions ru(VI) + U(V), ?u(IV) + U(V) and the Pu(III) • HO,, BCV) + SO, are responsible ala. Comparison between the calculated and experimental data on the kinetics of Pu(Vl) reduction in the presence and absence of uranium and on the kinetics of Pu(lV) oxidation as well as on the equilibrium concentrations of Pu(VI) and Pu(IV) made It possible to find the reaction rate constants early unknown for concentrated solutions of HNO, and reaction rate constants that cannot be determined experimentally: PuCV) + Pu(V), Pu(IV) + Pu(IV), Pu(III) +Pu(V). U(V)+Pu(VT),U(V)+PU 1. Vladiffiirova .'...V. iiadintsionnaya khimiya actinoidov, M.: Energoatom- izdat, 198Э- 2. SolovKin Л.Б., Vladimirova I'.V., Kulikov l.A. Itogi nauki i tekhniki. T.12. VIMITT, J 985. i. Vladimirova V.V., Golub B.A,/Radiokhimiya 1988. Т.ЗО, SI. S.54?, 381 RADIATION CHHHSTHY. BfflAVTODR OP PLUTONIUK, NEPTUNIUM AN» I ._. ' URANIUM IH ORGANIC SOLUTIONS OP EXTRACTIONS SYSTEMS I B. UFedoeeev, H.V.Vladimirova, I.A.Roraanovs!caya, Zi.A.Arteoov&, M.¥u. Gublna- All-Union Researoh Institute of Inorganic materials, Moscow, USSR The extraction technology of reprooessing Irradiated nuclear fuel assumes a joint extraction of plutonium, neptunium and uranium from nitric acid so lutions, containing the indicated actinldes and fission products.with solut ions of tri-n-butylphosphate (TBP) in diluents. The ionizing radiation of fission products substantially affects the extraction properties of the sys tems (distribution coefficients of actinides and fission products;hydroayna- ndc parameters) and finally results in a disturbance of a prooess regime of the extraction. In this^connection it becomes necessary to practically study the radiation ohemistry behaviour of actinides In organic solutions. At pre sent this field of the radiation ohemistry of actinidas is investigated least of all. We carry on systematical researches of radiation chemistry behaviour of Pu(IV,VI), Np(IY,V,vi) and U(VI) In the system ЗОЯ TBP+n-dodeeane under the aotion of the radiation of Co. In this report the results of this study are summarized. The radiation chemistry behaviour of aotinides «as studied both in the in dividual solutions of Fu(IV), Up(VI) and U(VI) and in the solutions, contain ing mixtures: Pu(IV)+U(VI), Pu(IV)+Mp(VI), PuClVHPuCVI), Pu(IV)+Si(IV), Pu(IV)+Pd(II), Np with di-n-butylphosphorio acid (HDB?)f which is a principal product of the radlolysls of TBP. The rate of the complex formation for Put IV) with HSBP' decreases in presence of tJ(VI), Zr(IV) practically does not change in pre sence of Np(VD-Si(IV} and increases in presence of Fd(II). The rate of comp lex formation of Sg(7l) with HUB? decreases in presence of Pu(IV), ZrdWand U(VI) and increases in presence of Pd(II). The Intermediate product of the reduction of Np(VX) is Hp(V). The dependence of the Np(V) concentration on D has a vibrational character. At the definite values of D the precipitates are formed in solutions. Conditions of the formation, the composition and the solubility cf the pre cipitates depend on the concentration of actlnldea, -radiation doze and the presence of other metals. 382 REACTIVITY OF ACTINIDE IONS TOWARDS INORGANIC FREE RADICALS 5-92 IN IRRADIATED AQUEOUS SOLUTIONS A.K. PikaeV, A.V. Gogdlev, V.P, Shilovt A-M.Fedoseev. Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR The results of the study.of reactivity of actinide ions towards inorga nic free radicals in aqueous solutions» obtained by the pulee radiolysia method with spectrophotometry registration of tbe Bhort-lived species, are presented. On the example of a number of the reactions of Cl^t Bl*2~ and Y2" radicalB with Pu(III) end Np(IIX) in acid solutions and reactions of CO " radicals with the Ara(III), PutHI) and Np(III) (and alBo Ce(III) as the analogue of Bk(III)) in carbonate solutions the possibility of of linear dependences of rate constants logarithm, difference of redox potentials of reacting a pedes is under discussion* It has been found, that such dependences are to take place in the rate of similar electro static interaction and analogous structural changes of reacting species. As a rule, the rate of reactions decreases in the row: SO." >NO^yClg"> Br2~>Y2~ > The results obtained allow to suppose that in* the reaction of electron transfer the diffusion limit of the rate is reached at difference of redox potentials of reacting speciee ^2,3 V. For reactions with the complex mechanism the rate is much lower than the diffusion limit. For example, the reaction of U(IV) with C0~" in the saturated bicarbonate solution the rate ie equal to 1.4x10' M-1a~1» The possible reason for the slowness of reactions of oxidation of fourvalent actinide ions is th-i structural changes during the reac tion. For reactions of Pu(III) and NpOg+ with Clg" the considerable Increa se of rate constants has been observed during tbe increase of concentra tion of HC1. Since such changes in concentrations of HC10., Lido, and HgSO. do not cause the same effect, the conclusion has been made that the reason of acceleration at reactions is the formation of intersphere chlorocomplexes* It has been shown that in alkaline solutions 0~~ radical reacts with Np(Vl) faster than with Np(VII) in spite of higher oxidation potential of tbe latter. It has been supposed that one of the reasons of this effect is higher negative charge of the Np(VII) ion. Tbe comparison of reactivity of OH radicals and secondary inorganic ones has been done. There are many differences in oxidation reactions of ions of four + valent aetlnides. In particular, OH radical oxidizers ions of Am02 and Pu(IV) with the rate constants 3x10е and 2.4xt08 M"1s"1, The influ ence of reconstruction in the structure of actinide ions does not take place during this process. It is possible that OH radical reacts via addition to the metal ion or it abstracts H atom from the coordina ted molecule,of water. This fact makes OH radical different from ra dicals S0^~, NQ-, Clg and others, for which these ways of reactions do not realize. 383 THE STUDY OF KINETICS OF 0" REACTIONS WITH PLUTONIUM (VI) AND AMERI CIUM (VI) IONS IN AQUEOUS SOLUTIONS BY PULSE HADIOLYSIS METHOD 5-9? A.V. Gogolev, A.M. Fedoseev, V.P. Shilov, A.K. Plkaev. Institute of Physical Chemi.etry of the Academy of Sciences of the USSR, Moscow, USSR In aqueous solutions» saturated by nitrous oxide, with the alkaline concentration 0.5-2.0 M the oxidation of neptunium (VI), plutonium (VI) and americium (VI) has been studied under the action of microsecond pulses of accelerated electrons with energy 5 MeV. It has been obser ved, that after the pulse action optical absorption, characteristic for the neptunium (VII), plutonium (VII) and americium (VII) ions, appears. From the increase of optical absorption of ions of hepta- valent actinidas ( in microsecond time range) the rate constants of reactions of the hexavalent actinlde ions with enion-radical 0" have been determined. From the decrease of optical absorption in millisecond time range the rate constants of reactions between pen- ta- and beptavalent actinides have been evaluated. The influence of redox potential of reacting species on the rate of reactions is under discussion. AH APPLICATION OF ACTIHIDES 10 HETEROGEHSOUS RADIATION- 5-94 CHEMICAL SYSTEKS H.A.Kalashnlkov, S.S.Kallnlchenko, I.K.Shvetaov. Kurohatov Institute of Atomic Energy, Mosoow, USSR The possibility of H20 thermal and radiation-thermal decomposition in he terogeneous systems at temperatures below 1000°K is considered in the paper. The results of preliminary investigations of the hydrogen formation rate de pendence on water steam density at irradiation of the system by U-235 fissi on fragments and without Irradiation are given. The problem of feasibility of IL>0 effective radlolysis in heterogeneous systems was considered as long ago as in early бо-th l\J . Later on ideas on possible ways to increase the water and water steam radiolysis effioienoy in heterogeneous systems on the basis of disperse oxides have gained wide ex tension [2,3J . However, hopes on a speedy attaining the H20 radiolysis high efficiency in studied systems were not justified for long» Only in the recent years a number of data indicating effective radiolysis potentialities has be en obtained. We succeeded in obtaining high efficiencies in various variants of organi zation of the HgO decomposition process than in homogeneous radiolysis of wa ter and steam; but the obtained G(Hg) values turned out to be Insufficiently high to be of practical use. Therefore, the search for conditions at which the Нг0 decomposition efficiency in heterogeneous systems can be increased, was continued. The following, logically evident step was carrying out investi gations of Hg0 behavior in heterogeneous systems at high temperatures and wa ter steam elevated pressures • In this case the thermal dissociation contribu tion, if any, should be taken into acoount. A convenient charaeterlstio of H20 molecules, stability in various conditions is the thermodynamic potential: A Cr = AH - Тле. (D Fig.1 shows the *G dependence on temperature for HgO. At low temperatures and under conditions when лЗ reaction is insufficient, the entropy term in formula (1) is practically not taken into account in determining the efficien cy of H20 decomposition. But, as it was shown in paper f47 • the entropy term role can be essential in heterogeneous systems at high temperatures. Conside ring the role which can be played by the change in entropy, it is of Interest to investigate the thermal and radiation-thermal decomposition of H20 in hete rogeneous systems where formation of intermediate compounds with great chan ge in entropy is possible. Based on publication data and results of investigations carried cut early, the authors have considered the possibility of thezmal and radiation-thermal HjO decomposition in heterogeneous systems at temperatures <1000°K. Here it should be noted that in a homogeneous system H20 begins to be decomposed at temperatures >2000°K. Therefore even the possibility of HgO decomposition at temperatures «1000CK Is of Interest too. In figs. 2 and 3 are given the results of relative rate measurements of H2 formation at the thermal H20 decomposition (in the Si02 presence at *Ы000*К) depending on an air amount in the system and water steam density, respectively. Ео.ЗакЛбО? 385 Fig.4 indicates the results of measurements of relative rate of H, release at the HgO radiation-thermal decomposition (in the SlOg presence at T-700°K).The intricate shape of the dependence of H„ release rate on the «rater steam densi ty isf probably, associated with an inclusion in the process of various adsor ption states «hose density of filling and efficiency of use is affected fil ling density by the water steam density.From the figure is seen that at the H20 radiolysis in heterogeneous systems the Kg release rate can be higher than in homogeneous ones under the same conditions.Based on tentative results of mposition is possible at T«1000 K; 2. hydrogen release rate at HgO decompositi on in heterogeneous systems (at T»1000°K) depends on air amount in the system; 3. Hydrogen release rate at Hg0 radiation-thermal expansion in heterogeneous systems depends on water steam density. The obtained results make it possi ble to expect to- get high rates of hydrogen release at an appropriate selecti on of the system's composition and conditions under which the H20 decompositi on is performed. - Vu ОЙН), kcal/mDle H2,rel.units -If го ULUHU Fig.1.Change of thermodynamic Fig. 3. Dependence of relative potential in HjO Vu on air amount (T a 1000 K) V„ , rel.units *?/W Fig. 2. Dependence of relative Vu on steam density Dependence of relative VH4 at H?0 radiation-termal decomposition (т = 700 к) References Veeelovskii V.I.,//Jroc. of the Inter Gonf. on Jeaoeful Utilisation of Atomio Energy. Geneva, 1955. .Strelko V.V. et al. Radiation-chemical prooessss in oxide-base hetero. geneoua systems. M.: Bnergoizdat, 1981. • Kotelnlkov V.A., Terenin A.M.//DAH SSSR. 1967.V«1.174. P .1366. ,Kasai P.H. et al. 113. of Ehys.Chem. 1977. Vol.81. Р.15ЭТ. ANALYTICAL CHEMISTRY THE LATEST ACHIEVEMENTS IN ANALYTICAL CHEMISTRY OF ACTINIDES 6-1 b,F,Myasoedov>l,A.Lebedev. Vernadsky Institute of Geochemistry end Analytical Chemistry of the Academy of Sciences of the USSR,Moscow,USSR This report presents a review on new methods for separation and determinat ion of actinides which methods are widely used in analysis of actinides in tec hnological and environmental samples. Special attention has been paid to obtai ning and stabilizing transplutonium elements(TPE) in extreme oxidation states, and their use in analytical practice resulted in expanding possibilities of methods for separation and determination of TPE. Solvent extraction,sorption and extraction-chromatography are the basic methods for separation of TPE. Methods of separation in gaseous phase and some other methods such as precipitation and coprecipitation are applied, however, to a lesser degree. Trends of development of these methods including those of various types of membrane extraction that succeeded in separation af TPE in both trivalent and other valent states have been shown. Attention has been paid mainly to consideration of up-to-date methods for determination of actinides«special distinction of such methods being low limits of determinationjhigh precision and selectivity. The cC- and У* spectrometric methods using semiconductor detectors have been the most developed among vario us methods based on registration of nuclear radiation. A tremendous success has been achieved in development of emissian-spectrometric methods for determi nation of trace amounts of actinides and various impure elements occurring in samples of actinides. Sensitive mass-spectrometric methods are widely used for determination of both isotope composition and content of elements in various samples including those which are highly radioactive. More simple and precise titrimetrie methods of analysis based on using oxidizing-reducing or complexi- ng agents are developed successfully. A large number of coulometric methods for determination of americium and berkelium characterizing high precision and sele ctivity as well as luminescence methods have been developed. Using lead molybd- ate as the matrix of erystallophosphors it ie possible to determine 0.01 ng of neptunium(vU= 1713 nm),0.5 ng of plutonium(U- = 1986 nm) and 0.5 ng of uranium UV = 507 nm). Determination of 0,1 ng of americium iX= 696 nm> can be underta ken with NaBHWO^}, crystallophosphor. References 1. Myasoedov B.F.W Inorg. Chim.Aeta. 49B6.Vol.llO.P.23i. 2. Myasaedov B.F.// Talanta. 1997. Vol.34. P.31. 388 THE GROWTH AND TRENDS OF THE ANALYTICAL CHEMISTRY OFl g_g | ACTINIDE ELEMENTS AS REFLECTED IN THE STATISTICAL •—- ' EVALUATION OF ITS SUBJECT LITERATURE T. BR A UN Institute of Inovgania and Analytical Chemistry, L. Edtvus University, 1443 Budapest, P.O.Box 283, Hungary This paper is an effort to identify the structure, distribution and sources of the analytical science of actinides. Based on the principle that the knowledge base of any science field is to be found in its published literature and that any new information builds upon past publications the statistical distribution of publications) citations and references is employed. It is shown that our present system of scientific .communication depends almost entirely on. the primary journal literature and in each field so also in the analytical chemistry of actinide elements the concept of the research front is prevalent. This, briefly, says that in any point in time there exists a set of articles belonging to the given subject literature which constitutes, the active state of the subject at that point in time. Based on these concepts the changes in the field of analytical chemistry of actinides are evaluated statistically and key areas of development are identified. 389 тяв озя о; SMIDABD нвлаюсв EWBBIALS П АЯАИИЫЬ [ТО] свжатзхвг or «витт АГО ялкжпт I Z—I I. У. Byzhlnskli, Л. V. 3topaaov, Ehlopin Radiol Institute, Leningrad, OS8B The procedure of earning out the quality control la analytical che mistry demands, the uae of certified analytical methods. On* of the main components of euoh control InoludM th» ива of standard reference matorl- al« (SB» for the purposes of calibration of the instrument», for measure ment aoouraey control and for direct use in eoaparative methods of analy sis* In the world praotlco or* known the 3RM produced by IBS, ЯВЬ (USA.), OBi. (Franco), СВИ (Buroatoa), XAIi. These SBB are In use for walysls of uraniun and Plutonium compounds. Considering the variety of nranlun and Plutonium ВВЦ* one oan divide them Into three groups* - SSM in which the content of main coapenent is certified. These are me- tallio uranlua and plutoniua, their oxides, tetra- and hexafluoMde of uranlun, plutonlum sulphate, the alloys U-ll, V-Ho, V-Pn, uranium car- hides, uraniun ores, the spike solutions of and - SBI In which the oontent of admixture elements Is certified. These are metallic uranium and plutonlum and their oxides, uranium tetrafluoride, the alloys of uranium with different metals; • SBH of ieotopio composition in the form of nitrate and sulphate of Plu tonium, metallic uranium and its oxides. In this communication the results of the work oaxrled out in the Radium Institute axe presented. Biis work «as oonneoted with the preparation of uranium and plutonlum SBH of the first group mentioned above. One of the possible methods of 3B> certification, 1. e. the determi nation of the certified values and their confidence limits, is the use of several Independent teohniques with the confidence lirt-lej of the ease range. It is desirable to perform the analyses in different laboratories. In this case the systematic errors of different methods can be considered as the random ones in the process of evaluation of the total error. By this method the content of uranium in 38m" of oxide-peroxide was certified. The analysis was carried out in 16 laboratories by means of different methods - peroxide gravimetry, poteutloaetrlo titration methods (a variants), oculometry, visual titration, inopotentiometrlo ooulometry. The BSD of these methods lies between 0.0002 and 0.0012. The certified value was determined as 84.80 % with the confidence limits * 0.02 %. Due to the vide use of aass-apeotrometric method with leotopie dilution for analysis of uranium and plutonlum materials the SSM of spike solutions are of great interest. Some prepared and certified SBm° are given In the Table. 390 The Spike SHU SBII Content of Certified Confidence Units of main isotope, the certified value, * «8/8 •8/8 233o >97 1,0761 0.0006 2350 >99.99 9.528 0.003 236„ >99-9 9.881 0.004 азе,, >99.9999 9.282 0.004 гз^азв,, 2.0080 0.0016 (1:1) 1.0174(233/236) 0.0006 2«Pu >94 0.9079 0.0010 236P» ^95 172.5 Bq/g 0.7 Bq/g 238Su >99 354.8 kBq/g 0.7 kBq/g Die 3S* of uranium spikes were certified mainly by means of two methods - ^avimetrieal potentionetrlc titration using Daries-Gray- -BBL technique with modification for aliquots in the range 5-10 ng of uranium end by means of isatopic dilation mass-speetrometry with double spikes and internal calibration procedure. She2 «Pu SBM was certified bj means of ooulonetric titration, end238 Pu were certified by means of oi -spectrometry. Several years ago a significant interest was shown to the method of mass-speotrometr? with internal calibration (internal standard). In this connection the Radius Institute and Analytical laboratory of азз 23 the IAEA, prepared and certified SMt which contained а, Ч 2«Pu and2 * 391 ЙНЮТЕ ягАыгтасль OOHTROL га ген ишь ЫИКШЕНТЛЬ I 6-4 I REPROCBSSIHO AT PILOT PLABTS '— A.G.Vradii.I.A.Korotkov, li.P.Halafeev, En.V.Henard, H.V.Heimoev, H.A.Haunov, A.U.Sirotinin, V.a.uetyugoy. All-Union Research Institute of Inorganic Material», Moscow, USSR An "on-line" system has been developed for remote analytical oontrol of the content of main components in eolations of aqueous extraction processes for spent FBR fuel reprocessing at pilot research plants. The system makes use of flow j'-absorptiometers with Cd-Te detectors to determine the total content of uranium and Plutonium in ertraots and reextraota in the concent ration range from 10 to 300 g/dm3 with an error of 1-2 g/dm3. Flo» Jf-apeot- rometers with Ge-deteators vere employed to oontrol у-emitting fission pro ducts, Pu239, n237 in extracts end to control Pu239, Hp237 in Plutonium and uranium concentrates. The lover level of detection of gamma-emitting fission products was approximately 100 Bq/dm3, that for Pu 39 was 200 ag/dm3 and that for Up2" was 20 mg/dm3. Immersion and flow 392 MtRACIIOH CHROMATOGRAPHY IN ANALYTICAL CHEMISTRY. OF ACIINIDES 6-5 V.K.Markov, V.I.Astafurov, A.V.Yablooiutin, V.N.Prolova. All-Union Research Institute of Inorganic Materials, Moscow, USSR Extraction chromatography ia a relatively new and apparently most effici ent method for an analytical separation of inorganio substances. This paper generalizes data on the use of extraction chromatography in the analytical chemistry of actinides, gives examples of separation of elements and their valent forms, extraction and purification of actinidea in the analysis of complexly composed samples- Consideration ia given to the main criteria used in the choice of extractants and carriers, sorbins layer sizes, waahup solut ions and eluents. Practical recommendations are given as to how to conduct investigations in extraction chromatography and to choose the optimized con ditions of actlnide separation. Consideration is given to the dynamics of the progress of extraction chro matography methods and the theoretical bases. The classical methods of ext raction chromatography retain their significance and are widely employed for the analytical control of spent nuclear fuel reprocessing, scientific rese arch , oontrol of environmental objects. In particular, chromatography sys tems with methyltrioctylammonium nitrate and di(2-ethylhexyl)phosphoric acid applied to a teflon surface allow the selective extraction of Hp and Pu from high radioactivity solutions and uranium concentrates as well as the separat ion of the valent forms of those elements. Recently "solid extraetants" - solexes that are a granulated porous poly mer impregnated with a liquid extraotant have found increasingly wider use as sorbents for extraction chromatography. She use of eolexea increases the potentialities of the instrumental remote separation of actinides when analy zing high radioactivity solutions. The paper presents the results of investi gations into solexes based on tributylphosphate, trilsoamylphosphate and tri- octylamine for the purposes of selective extraction of U and Pu from complex ly composed solutions* Data have been generalised on the analytical usage of aolexes of other types. An ever increasing significance is being acquired by combined methods of actinide determination on the basis of extraction chromatography in combinat ion with nuclear physics and physico-chemical methods of measurements. Consi deration is given to the examples of usage of such methods to determine tho rium, uranium, neptunium, Plutonium and americlum. Widespread potentialities for the automation of the analytical control of spent nuclear fuel solutions and effluents are opened up through the use of high-effioiency instrumental extraction chromatography. Detection of actini des at a ohrcmatographic oolumn outlet by their alpha-activity or light ab sorption of their complexes with organic reagents permits determination of the low contents of Th, If, Dp, Pu and An in complex composition solutions. Thus, with a sample volume of 5 ml and spectrophotometry detection the lower limit of detectable neptunium contents is equal to 1.10"' g/1. 393 РЯОТОИШИЕ30ЕНСЕ OF COTSTAIXOPHOSPHORS FOB THE DETERMINATION OF I ~~ шшш, шишига, рьтаяноы АНБ лшиохш >—-— Tu.P.Bovikov, s.A.Xvanova, V.B.Oliva. Veraadeky Institute of Oeoobemistry and Analytical Chemistry, Academy of Sciences of the USSR, •oseow, USSR TO» properties of uranium, neptunium» plutonlum and americium to cause luminesoenoe of some hard matrix** - orystallophosphors servo aa a base for too determination of these elements if their content in the sample is 10"*g and lower. For the practical purpoaee together with making sensitivity, se lectivity and expressiveness higher the photoluminescenoe methods ought to be worked out for the determination of several elements in their content in one sample. ТЫ в task of the determination of uranium, neptunium, plutonium and amepiolun was being solved hy searching for orystallophosphora, studying their properties, meohanien of luminescence, influence of the elements deter mined on the rightness of analyses. To prepare oryatallophosphora, chlorides, fluorides, molybdatds, tungatatea were used. Luminescence spectra have been found to hare some broad bands in the near l.r. region independently of the oxidation state of introduced elements and the conditions of u.v. Irradiation The bast conditions for the uranium, plutonium, neptunium and amerlclum de termination oan be established when you use crystallophosphora on the basis of lead molybdate and HaBi(W0.)2 /1,3/.The method that included introducing the solution studied into the powder matrix, further drying, blend calcina tion and measurement of the intensity of the luminescence has been suggested. This method presupposes the use of a SDL-1 luminescence spectrometer or a speoially designed photometer with interference light filters and two detec ting channels in the near i.r. region of the spectrum. The determination of neptunium and plutonium, the quantaties of which can not be differed iu one order, is possible in the presenoe of Kp quantatiea of uranium and lumines cence quenching elements up till 5 mg of salts in the 0.1 ml samples. That allows In many cases to analyse without preliminary separation of the impu rities from the elements determined. Using the crystallophosphor based on le ad molybdate, it is possible to determine in the same sample up to 0,01 ng ир(171ЭшО, 0.5 ng Pu(1986nm) and 0.1 ng U(507um), if NaBi(W0.)2 is taken as the crystallophosphor base americium can be determined up to 0.1 ng(696nm). Refsrenoes 1. Hovikov Yu.P., eilva V.B. et al.//J.Radioanal. Nuel. Chem., Letters. 1986. Vol.103, H 6. P.337. 2. Novikov Yu.P., Karyakin А.У. et al.//Speotroohimica Acta. 1986. Vol.41B, И 7. P.771. »4 lUMINESCBHT DBTERMIHATION OP NEPT'JNIUH Ш URANIUM | 6"? V.A.Rysbukhin, U.P.Volynets, S.A.Ivanova, Yu.P.HoviJcov. Yernadaky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR» Moscow, USSR Ultra-violet Irradiation induces infra-red charooterirtic lumineeceaod in erystallophoaphorea containing neptunium* It пае a Ъела for creating of cor responding determination method with the use. of calcium fluoride crystal!орпоя- phor flj. However it demanda previous removing of uranium because of its strong quenching influence on neptunium luminescence, when uranium being present in concentration of 3-4 orders more, than neptunium. Now this stage of analyseв is being carried out by liquid extraction, after what aqueous neptunium contained phase is applied to calcium fluofide powder with further evaporation and drying. To exclude a liquid extraction stage a direot filtration of nitric acid solutions contained uranium and neptunium was used through a calcium fluo ride powder bed In a form of pellet. Sorbtion of ohemically stabilized nep tunium as Np(IV) and removing of a bulk of uranium were achieved during fil tration at the seme time* Pellets prepared in a such way may be used direct ly for luminescent analyses after appropriate thermal treatKent. The influence of acid concentration, chemical stabilizers, pretreatement and followed washing of pellets, chromatographic filtration rate was studied on degree of neptunium sorbtion and uranium separation* Concentration factor 10* for neptunium-uranium pair was achieved. That allows to determine neptu nium in nanogramme amounts at initial uranium-neptunium ratio about 10 . Referring samples were prepared by addition of known neptunium amounts to analysed probes* Photometer conetracted in Vernadaky Institute was used with UV exitation of luminescence spectra and the disorete photon registration* Proposed method is simple* fast and does not need a special equipment. Reference 1. Novikov Yu.P., Karyakin A.V. et al.//Spectrochim. aota. 1986. Vol.41B, И 7. P.771. 395 ТКВ ШШЖЗСВЯТ AHALiZBR POR URAHH)H(VI) DETERmTHATIOH Г" e.I.Boaanevakaya, A.K.Ohlblaov, V.A.eorpenke, ll.A.Iebedeva. "~ Inatltute of Oeoeherlatry and Analytical Chemistry of tin Academy of Sciences of the USSR, Mosoov, USSR "!he luminescence method is widely used for determination of low concen trations of uranium In solutions and «olid materials. It» detection Halt for urnnyl is normally Ю g/ml and la limited by interf erring elements which any aot aa fluoreaoeaoe quenchers or exhibit the Intrinsic lumines cence. Seduction of the detection Holt la important for solving many geo- cbamlcal problems aa well aa for determination of uranium in natural water». A lower detection limit may be attained by using nigh Intensity pulsing aonroe and electronic system vbleh elesdaa\?s the background emission and increases the slgnal-to-nolse ratio. A new laser-induced fluoresoenoe method was developed for uranium deter mination with a low deteetlon limit baaed on use of a repetitive pulsed laser aa an Intense ezoltation aource, time discrimination with a gated deteetlon system for suppressing the background emission,and an averaging technique to increase slgnal-to-nolse ratio* lbs difference between the lifetime of t'a uranyl fluorescence and back ground «mission was found to be greatest for the uranyl complexes with phosphoric acid or aodium polysilicate. The luminescence lifetime of the uranyl complexes Is shortened la presence of certain Inorganic ions and organic substances. It was established that the quenching of uranyl fluo rescence by Inorganic ions can occur by both electron and energy transfer» The complexatlon of the uranyl Ions with phosphoric acid should be recom mended for determination of uranium In presence of cations (Ca , Hg , Cu etc. )• However the determination of traoe amounts of uranium in pre sence of anions (01", Br" etc.) should be performed for uranium complexes with sodium polyeilioate, The quenching action of organic sube*«noes oan be diminished by dilution of analysed solution and by addltior of perchlo ric acid (0.2 vol.*!). The laser-induced fluorescence method was utilised to dlsign the luml- nesoent analyser for uranlum(TO) determination. The analyzer consists of nitrogen pulse laser "ЛГИ-Я", photomultipler tube as photodetector($3y - 79), operated in the photon counting mode and ulorooonputer. Using the analyzer It made possible to perform the uranium determination both in static and dynamlo conditions in the concentration range Ю"7 - 10"'g/ml 10 J1 with Sr . 0.05 and W" - « g/ml with Sr » 0.1. Sample volume is 5 ml, the time wooded for analyses is I min. 396 ОП ГНРНШН0Е OP ACID-BASE EQUILIBRIUM ON CHARACTHilSTICS OF \~~6-9 siBcraapHOTaiBiHic HMHQDS OF UKABIDH SOWTIOH AHAISSIS I—— I.H. Asian' e?a, Bn.G.Teterln. All-Union Reaeax-oh Institute of Inorganio Material», Moaoo», USSR Uranyl Solution absorption Spectra have been measured in a aide range of uranium concentration», solution acidity and nitrate ion contents. It la shorn that in dilute eolations uranyl Ion la present as a free ion UOg .6HjO. The spectrin» of this form of uranyl ion exlateaoe (£4,5 • 7.88) la uaed to dateralne uranium In solution*. It la established that apeotrua changes depending on cold-base equilib rium condition-* oan be explained by the foraatlon of five different forms of uranyl Ion exiateooa. Their individuality i» confirmed by the preaanoe of individual apeetraj 1) partially hydrolyxed fore (fA1 g • 15.6); 25 free form ( £w+ • 6.99; £4,5 - 7.8a; 427." 6.09); 3) I** nitrate fore ( £W4 .8.14; S+15 • 9.74) £437 • 8.82); nd 4>- II nitrate form tei17 - 10.2» Sla8 • 10h r t№m (s^ m 11.б; ^да « 14.7; S+5l • 14.4; 467 • 8.6). It la ahown that no more thar two forms oan simultaneously shown up in a solution. A technique has been developed for a direct uranium determination beginn ing from 0.01 g/1 In solutions of any salt composition. The technique la based on measuring the optical density in the — 415 nm band range. The forms of uranyl ion existence and the total uranium content are determined from the relation between the intensities the components of that band. 397 THE ЕШЯЖОТНЕИШ, ATOMIC ABSORKTIOH SPBCTROUECRY TECHNIQUE FOR 6_10 DEIBMtraATIOB ОТ НОНМШ IH PRESENCE OP ШАИШКП) Ш HITBIC SO- ' IWTICff H.A,Abuswida, H.B.'fireesh. Radiochemical Department of Trajura Nuclear Reeetroh Casta? (Time-}. P.O.Box 30678 Tajnra, Tripoli, Libia A.G.Haelennikov. Institute of Physical Chemistry of the Academy ox Science, of the OSSR, Moscow, USSR Zu.G. Tatzy, Sall.Ku'zminr Yamadsly Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR She noble metals of Ru-subgroup are known to form in sufficient amount in the burn-up of the nuclear fuel» Nowadays the problem of their recovery is the problem of great edeutifle and practical interest. Therefor*, the deve lopment of new teohnlque of noble metal determination in solutions contai ning uranium пае become a subject of present reports* The atondo absorption technique is known to be usually used for noble metals determination. Kh-elec- trothermal ctomio absorption determination technique in nitrio uranyl soluti ons - 1Ы НТО- + 100jng/l U(YI) - was developed. FU-9000 Atomlo absorption spectrophotometer equipped with FU-9095 Video furaance programmer was used in all experiments. She signals were measured at the absorption peak maximum and slmultanloual7 recorded by chart reeorder. All the measurements were carried out In a pyrolitio coated graphite tubes, and the optimum conditions for the measurements «era ohosen experimentally: drying at 110°C, ashing 1350°C, ato- miration 2500°C. The detection limit for Rh determination Is nitric acid so lution was found to he ljwg/1 with Sr-0,05 in lOjul of 15jug/l solution. The calibration curve appeared to be linear in condition range 1-100 je/1 Rh. The effect of D(TI) on the analytical signal of 4jkl/l Rh was studied In nit ric acid media containing 1000jtg/l U(VI). uranium{VT) appeared to inhabit vaporisation of Eh to certain extent, when It's oontent In solution was more than 100*tg/l» xne Interaction of uranium oxide produced during ashing with graphite surfaoe seems to be the main reason of Rh signal quenching in this process. The surfaoe of graphite tube was found to be dlffloult to clean the further determination. Therefore, the electrothermal atomlo absorption spec trometry determination of Rh and other metals of Rn-snbgroun is possible af ter the reduction of the uranium content in the sample solution. 398 DERIVATIVE COULOGRAPHY AMD ITS APPLICAMOH IN ABALYTICAL 6-11 CHEMISTRY OP TRABSIIRAinUM ELBURTS V.N.Kosyakov. Kurchatov Institute of Atomic Energy, Moscow, USSR She derivative oculography is based an the recording of an electricity amount increment with a potential change unit 1а в system «Jure the rat* of potential scanning oapable to eneure the eleetroohemloal equilibrium. The eu- rve reoorded in these oonoitloaa corresponds to the equation attfcgo) do ш »T» exp RT nhere n - the number of the electrons participating in the rcdox-reaotion; F-Fareday ooastants m - the quantity of the element in the oell in gram- atomai К and Bg - the equilibrium potential of the system and the formal po tential of the reversible redox-reaotion respectively and represents a sym metric peak with a half-width 90/n mV, a night ь - a^ , (2) and the TiBTlmun positioning at BQ . Analysis of the curve dQ/dS versus E re sults in obtaining the important Information on the redox-reaotion under in vestigation (the value of the fomal redoz-potentlal; the number of the par ticipating electrons» degree of reversibility) and dlreot measuring of the quantity of the element in the cell. She maximum value of the potential scanning rate| required to ensure electrochemical equilibrium conditions, oan be used to ehanaoterize the redox-reaetlon klaetios. The potential range usually applied covers about 1.5 v9 allowing to study several redox-transitions of an element, or to determine the oontent of se veral elements at the some time. Formal redox potentials of many valant tra nsitions of V, Яр, Pu correspond to the range from 0 to 1.5 v. When strong coaplexing agents are used Am and Bk can be added to this series of elements. Spectrum like mode of recording made the results very descriptive and easi ly computable. Bw use of a special electrochemical cell In a combination with appropriate scanning and reoording instrumentation allow to realise all these possibilities. Several versions are possible there. 1. She most reliable teohnlque Is reoording the value of dQ/d£ versus the Measured equilibrium potential. At least two versions are possible herei a) to measure Q versus Б with the following transformation with a oomputer and recording in a derivative form; b) to record the derivative ourves as &Q/aE versus B, ensuring dumping of Oe ooulometer indications in defini te intervals, aE, likewise in [1] . The redox reaction itself can be carri ed out in potentioetatic or galvanostatic conditions. A tetraelectrode cell must be applied in the first ease (potantioutatio) and a trieleotrode cell - In the second one. In version "b" the quantity of the element is determined by the equation 39» в • .Tim - (3) лВ.п 2. At tba eondltlon whan tha defined and •qullibriun potentials an •quel «cording of dQ/dB versus defined potential of th« working eleotrodo oan ha applied. Snob conditions oan *м achieved for exenple, by using of a spaeaporoue working electrode «Murine as extremely high rata of tht ele- otroehaaloal prooess and by controlling of th* potential scanning velocity. Suoh • teohniq.ua allows to study aeae irreversible redox tnmeitiona. At laaat two versions ara poaalbla hara aa wallt a) to raoord tba ourrent passing through the oall at potential soannlng with tta oonstant Taloolty ensuring tha fulfUacnt of tha above oondltlonai b) to record »в/ дВ v«- raus В at a nonlinear potantial scanning, whan tba «panning velocity it inversely proportional to tba ourrent intensity. Tha version "a" raaulta In routine Toltaaawtrlo «easurenente at an optimised potantial aaaaning velo city (Flg.Dc In thla oaaa tha quantity of tha eleaont in tha oall la de- temined by tha following aquation: .1.06.1n-0 6 (4) where v - tha potantial aoanning velocity. Я» version >b" requires a spe- olal lnatmawnt for nonlinear potantial aoanning. I, mil -0.4 Flg.1. Toltaaawtrlo Curvaa of tha Reversible Redox transitions of lap- tuulua (0.18 ag) In 1 aol/1 BBOj. Potantial Seaming Velocity - 10 ur/aI.. 1 - Bp4*/»3*! 2 - «POo***/«po/ | Reference I.Kosyakov V.B., Allasskov R.R.// Radiokhialya (Rusaian). 1986. V. 28. • 4. P. 533-538. 400 COULOHETRIC DETERMINATION OF URANIUK AND РТЛТОЯ1Ш1 CONTENT IN HIXBD FUEL DISSOLVED IN NITRIC ACID SOLUTIONS 6- I.G.Sentyurln, Yu.M.Kulyako. Vernadsky Ins ti tut о of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR* Moscow, USSR A high precision method for determination of uranium end plutonium, the main components oi nuclear fuel, has been developed with the help of controlled potential oculometry* The method being absolute, based on funda mental lhW5 of electrolysis, does not need the use of standard substances. Coulometric methods for determination of uranium as well as that of both uranium end plutonium used earlier never had a precision less than 0.2 % for samples containing upto 200 mg U. These methods Buffer from the main drawback of high corrosion activity of hydrochloric acid solutions» which have been used as as electrolyte in such methods, in respect of the Pt- electrode in the region of the positive potentials. The present report describes the coulometric method using nitric acid solutions as electrolyte for determination of uranium and plutonium in presence of each other. The special feature of this method is the use of a modified platinum-electrode prepared by specific adsorption of Pb ions for which the hydrogen deposition wave ehifts to the cathode region by 0.? V. The background signal decreases by 100 times in this region, and quantitat ive reduction of UO-j to tr"1" tafees place at potentials less than 150 mV (here and hereinafter all potentials are expressed with reference to silver chloride reference electrode). The mechanism for reduction of Uol+ ions on the modified electrode involves two stage's viz., a fast step of reduction of U(VI) to U(V) followed by slower stage of electrochemical reduction of U(V) to U(IV) t the rate constant for the latter step being fcQ- 2 X 10"^ ca s"1 f dl* 0.85, Jb* 0.15 and (ol + £) - 1.00 * 0.01 J. Diaproportionation reactions of U(V) to U(VI) and U(IV) donot seem to take place. Determination of plutonium has been carried out by using the easily reve rsible reaction; Pu + e *. Pu*+ at the potentialsWO +_ 180 mV. The Pu-determination can be undertaken before carrying out reduction of uranium as well as after that in which case the electrochemical oxidation of U(IV) to U(VI) has essentially been facilitated by the presence of Pu,since oxidation of U(IV) to U(VI) is caused by Pn(IV). Determinations have been made in I - 3 M HNO, containing O.05 И FbCNO,)^ and 0.05 M HHpSO-H. The error in determination of 10 mg Pu end 15 mg 0" has not been more than 0.1 %. Reproducibility in determination of the ratio of Pu/U has been achieved upto 0.0} %* All measurements have been made by the precision coulometric device AKT-IOI of 0.02 % precision. References 1. Davis W., Gray W,, McLeod K.C.// Talanta. 1970. Vol.17- P.957 - 944. 2. Kuperman А,Та.. Moiseev X.V., Gal kin a V.N. ,Nikitskaya V.N., Yakushina G.S.// fiadiokhimiya. 1979. Vol.21. P.2I5 - 227- 26»3ак,1б07 401 COWTRObLED-FOIBHTlAL CODXOMKPRIC DETERMINATION OP URANIUM AND 6-^3 PLUTONIUM OUT OP ONE SAMPLB I.S.Sklyarenko» T.mctmbufcova, vernadsky Institute of Geochemistry and Analytical Chemistry of the Academy of Sciences of the USSR, Moo cow, USSR The actualityof method for simultaneous determination of uranium and Pluto nium out of one sample le caused by using these elements in mixed nuclear fuel* Controlled—potential ooulometric method proved to be the most suitable one for solving this problem» The electrochemical behavior of systems РиШ)/Ри(1И) and'U 402 COULOMETRIC DETBHUnUATIQ» OP NEFTUHIUM 6.14 ) A.I.Karelin, E.N.SemenoY, N.A.Uichallova. Polysechnlcal Institute, Tomsk, USSR Application of the controlled-current oculometry with detection of the po ints of equivalence by aroperometry with two indicator electrodes allowed to determine neptunium 1л the presence of the 1000-fold amounts of plutonium and greater than 10 000-fold amounts of uranium, iron and some other elements. Electrolytic solution allowed repeated many times titration of neptunium in single volume with transition of valence from (VI) to (V) and its reverse oxi dation* The equipment made it possible to titrate in the range of 1:2J0 mkg neptu nium with the volume 3:5 ml* Platinum was used as electrodes. The accuracy of determination was 0,2% for pure solutions of neptunium and increased to вошь percent a with titration of 1:5 mkg neptunium in the presence of high content of plutonium ( 1000-fold), The high selectivity is justified theoretically, the equations of current of a polarized electrode and amperometry with two indicator electrodes are derived* Theoretical results are confirmed experimentally. Improvement of end-point detection methods allowed to automate recording the points of equivalence and eliminate graphical treatment of titration cur ves. Three new methods of end-point detection with use of continuous and al ternating current are proposed. These methods are differential, and the mea - sured parameters are currentt voltage and polarisation of electrodes. Slack dependence of measured signal during titration, which changes the sign with the ratio of neptunium (VI)/neptunium (V) being in the rang» of 1, ends ее its sharp change of the sign and the absolute value in points of equivalence. The methods have all the advantages of amperometry with two indicator electro des. DETERMINATION OP URANIUM AND PLUTONIUM BY DIRECT AHD STRIPPING I g_15 VOLTAMFEROMETRY IN ALKALY MEDIA AND IN ACETIC SOLUTIONS IN THE I— ... > PRESENCE OP CUPFERONB M.Abuswida, Tenure Nuclear Research Centre, Tripoli, Libya A.O.Maslennikov, V.F.Feretrukhin. Institute at Physical Chemistry of the Academy of Sciences of the USSR, Mcsoow, USSR The determination of the concentrations and chemJ~al state of uranium (VI) and Plutonium (VI,V) in alltallne solutions ere of interest for oertain pro cesses of the treatment and storage of liquid radloaotive wastes» Traditio nal optical methods of the uranium (VI) and Plutonium (VI,V) determination and investigation are insufficient for the alkaline solutions because these actinides have very luw molar adsorptlvity in alkaline media. The determination of the above mentioned elementB in aqueous solutions 0.4-4 II NaOH is elaborated by us using the methods of classical and diffe rent pulses voltamperometry. Dropping mercury electrode (dme) ie used for tbe uranium (VI), plutonium (V) determination and platinum rotating elect rode is used tor plutonium (VI/. Uranium Is determined due to limiting current or to peak of the reaction U(VI) + ё —U(V) at the potential of dme equal to -0.89 V v.s. Ag/AgCl. The limiting current or the peek height are striotly proportional to the uranium (VI) concentration in the range 1.10"7 - 3.10"'' M U(VI). Some deviation from proportionality is observed for the concentration higher than 3.10"* M U(VI) due to the polymerizati on of urenatee. Plutonium(V.VI)ls determined with dme due to the limiting current of the two-eleotrons wave Pu(V) + 2e-»-Pu(III) at the potential -0.98 V. The limiting current of both plutonium (VI) and (V) is proportio nal to concentration in the .ange 8.10" - 2.10-3 II Pa. Higher concen trations of plutenium (VI,V) give tbe deviation from linearity due to polymerization of plutonium ions in alkali. Plutonium (VI) and (V) in 0.5 - 4 M NaOH is determined with the platinum rotating electrode at tbe potential-0.20V due to the limiting current or peak of oathodio or ano dic one-electrode wave. Voltamperometric determination of uraniuia and plu tonium (VI,V) in 0.5-4 M NaOH is not interfered by the addition of the following substances KaNO^ (2M), Цаж> (2M),NaF(0.4H), phosphate (0.2 И) and the ions of Al(III), Mo(VI), Cr(III), Pd(II). Tbe presence of Cr(VI) and Fe(III) disturbs the analysis of uranium however contribution of tbe reaction Pe(III) + e-~Fe(II) to uranium peak can be calculated from tbe height of the second peak Pe(II) + 2ё—Fe (o). To determine the low concentrations of uranium in natural and sea wa ter the stripping voltamperometry of uranium (VI) is investigated in aqueous acetic solutions in the presence of cupferone» It has been shown 404 that electrochemical reduction of uranium (VI) in the acetic solution with the pH 4-9 and molar ratio of uranium to eupferon 0*1 is one electron and irreveittible and takes place at the potentials of the elect rode from -0.32 V at the pH* 4-5 to -0.54 V at the pH* 3.3* The aorb- tion of the uranium complexes with cupferone from acetic solution is in vestigated at tn« handling drop mercury (bdme) electrode ao a function potentials of electrode, pH and uranium concentration. Freconoentration of uranium г>зщ the acetic oupferone solutions on the hdne surfaoe and consequent difference pulse voltamperomfctry permit to decreaee the detec tion limit of the uranium determination. 405 ELECTHODEPOSITIOH 0? ACTINIDE TRACES FROM AQUEOUS ДЬКАЫИЕ SOLUTIONS AND TRIBUWLPHOSPHATE B.Al.Medehem, F.Zantuti. Tajura Nuclear Research Centre, Tripoli, Libya,. IM.Siltn, V.P.Peretrukhtn. Institute of Physical Chemistry of the Academy of Scienoes of the USSR, Moscow, USSR Eleotrodeposition and «£-spectrometry are final stage of many techniques for determination of actinides in radioactive wastes and environmental samples. The electrodepoeition of mlcrogranmes of uranium and trace quantities of plutonlum-239, tborium-234 and cerium-144 on the stainless steel disk have been investigated. The electrolysis «as carried out in aqueous solutions of 0.5 - 2.0 И NaOH and the two-phase systems extract of actinides in TBP-aqueo- us solution of NaOH. It «as shown, that the electrodepoeition from solution Of 0.5-2.0 M NaOH containing 10"6 - 10"5 Ы U(VI), traces quantities of гз9Ри, г^*№, '^*Ca reached 97-1008 during 40 mla of the electrolysis at the current density of 0.4-0.5 A/cm and epeed of mechanical stirrer of 120-200 r.p.m. The presence of sodium carbonate (0.5Ы), nitrate (2.0И), nitrite (2.0 M), phosphate (0.2 M), fluoride (0.2 M) in alkaline solutions does not deorease the eleotrodeposition yield. During eleotrolysie from the two-phaee system: extract of ectlnide in 30% TBF in kercasie-aqueous solution of 1-2 11 NaOH the neutralization of nitric acid contained in organic phase, the back extraction of actinides into aqueous phase and their electrodeposition take place. Under theee conditi ons the yield of the prooesa reaohed 97-99Я during 40 mln of electrolysis. Changing the ratio of aqueous to organic phase from 10:1 to 1:5 doee not affect the electrochemical yield. Films of uranium and other actlnldea on stainless steel disks after wa shing and calcination meet all the requirements of J. -spectrometry. They have strong adhesion to the stainless steel disk, regular thickness in all points and produce sharp and good reeolved «C -peaks of urenium-234,-23B, plutonium-239. These teobniques may Ъв used for >determlnatlons traces of uranium, Pluto nium and other actinldee in liquid alkaline radioactive wastes and a spent TBP. 406 USE 07 **£Qt РОЯ ELEMENTAL ANALYSIS 6-17 S.A«Baklyev, A.A.Klet, Zh.Rakhmanov, Sb.Khatamov, E^S.Flitsiyan, G.A.Aripov, R.M.Bevahanov. Institute of Nuelear Physics of the UoSSR Academy of Sciences, Tashkent, USSR The '2Cf-baaed neutron sources characterized by a higher neutron yieldв, compared to other ampoule sources» and by a relatively long half-life proved to he convenient for the use in the analytical laboratories located far from the large nuclear oentree. The studies based on the use of californium sources are being carried out at aome scientific centres of the USSR including the Institute of Buclear Physics of the UaSSR Academy of Sciences, where the recent investigations on the practical application of californium sources of various intensity in some branches of industry, first of all in geology &&d mining industry, have been undertaken. The possibility to study large samples and to irradiate eeveral of them at a time {while analysing by long-life nuclides) appears to be the peculiari ty of НАЛ based on neutron sources, which conditions the necessity to take into account the changes in neutron flux and spectrum. The study of the 5 Cf neutron field distribution pattern in various ma terials allowed one to choose water as on irradiation and protection medium, as well as to find the optimum parameters for irradiation construction and to elaborate the methods of calibration against a primary standard for mono- and multlelemental analyses* Radiation security problems posed by powerful sources have been solved and the means of their transport have been worked out* Irradiation devices for different types of analyses as well as the sys tems for sample transport and analysis process monitoring have been crea ted. The work done demonstrated wide functional possibilities of the ?"cf sources utilization for different scientific purposes: well logging, ra diographic studies, neutron activation analyaisCin flux as Well), regis tration of capture radiation and of delayed neutrons. Several laboratories based on neutron sources have been organized, where the analysis of ore samples, the products of their processing and some technological products are done. The elaborated methods based on the sources with the yield of 10 n/s allow the determination of Au, Ag, *, U, Sct V, La, 3b, As, S, Gu, Se, Al, Si, На, К and P. Besides, the methods of neutron radiation determina tion of Fe» Ti, Co, CI, Ca, 2fi, Cd, Gd and Hg have been developed. Seutron-autoradiograpbic techniques to study the distribution of gold, Silver and eome other elements in microsectlon and large powder-like samples have been elaborated. They allow the solution of some problems of practical geology, aa well as the determination of sample representa tive! ia the analysis for gold. The experience proved the possibility to carry out 100 th. elememt determinations of the basic, valuable associated, rock-forming and ad mixture elements by a laboratory using one 10 n/s californium source at a lower cost compared to othur methods. 407 NEUTRON ACTIVATION ANALYSIS FOR TRACE AMOUNTS OF I 6-18 THORIUM, URANIUM AND NEPTUNIUM Ursula Niese, Birgit Gleisberg, S. Niese Central Institute of Nuclear Research, Rossendorf P.O.Box 19, Dresden 8051, GDR The long lived nuclides of the actinides are alpha emitters, which may be determined by liquid scintillation counting or alpha spectrometry as well as by a number of chemical methods. Neutron activation analysis (NAA) is characteris tic of having low detection limits. It is not only a high sensitiv method, it is also suitable for yield determination in case of isotope dilution activation analysis (IDAA). NAA was used for the determination of thorium and urani ..n in ultramafic rocks and meteorites /1/, of uranium in semiconductor silicon /2/ and of uranium and neptunium in samples of the primary water circuit and in crud of a nuclear reactor /3/. Separation was cairied out after irradiation, in case of determina tion of neptunium before irradiation the sample was separated. In general a mixture of several acids (HNO^, H?F2 and HC10.) served for the chemical treatment of investigated samples. In case of rocks a dissolution procedure of the irradiated sample was performed in an autoclave at 450 K. The most important stups of further chemical operations are boiling in HC1, fjminc, of the acid and redissolving in a mixture of hydrochloric and oxalic acid, sep aration by cationic exchange: first eluate (0.1M oxalic acid), second eluate (2M HC1), third fraction <6M HNOj). 239Np was extracted with Т0Р0 in xylene ob tained from the first eluate. The remaining water phase was combined with the second eluate. In this solution Rb and Cs were precipitated together with к by sodium tetra phenyl borate. The third fraction was evaporated for measurement of the rare earth elements. Separation was controlled by radiotracers Y, Cs, and Np added to the samples before dissolution. Investigating samples of nuclear reactor water (2-51) taken from a bypass of the reactor vessel and crud samples obtained from the cover of a steam producer, dissolution was carried out in a mixture of HNO, and HF, Anionic exchange was used for separation after performance of the valency states UVI, NpIV and PuIII. Separation was controlled by the tracers: 23BNp, 239Np, z38Pu. In a spent fuel solution (1.37 * fima has been determined /4/. In this case separation was carried out by extraction with TTA 5 % in toluene 239 (neptunium in valency state NpIV), after dissolution in 3M HNO,. Np was used as tracer. Samples of irradiated semiconductor silicon were treated with a mixture o_ 40 % H-F* and 65 \ HNO, In a platinum vessel. After evaporation a «dissolution 239 in 8N HNO, was applied and the Np built up after the irradiation was sepa rated using an anionic .*':romatografic procedure. Valency state of neptunium has ?38 to be again NpIV, performed by adding Fe{NH250,)2. Np served as a tracer. 406 A summary of results is given in table in a shortend form. Actinide Element Concentrations in Different Materials Actinide Material Concentration, pg/g 2Э8 и ro<.. 238и reactor Mater 480 237Np reactor water 0.2 2J9*24a pu reactor water 3.6 "»Np reactor water 0.02 "8U crud o.oe ч 237Np crud 0.01 \ 237Np spent fuel (1.3? % f ima! 200 238u semiconductor silicon 578 References 1. B. Gleisberg, S. Niese, И. Kramer, Chem. Erde, 47 (1987) 231. 2. U. Niese, S. Niese, ZfK-510 09B3), S. Hi. 3. U. Niese, 5. Niese, Isotopenpraxis, 24 U9B8) 77. « U. Niese, S. Niese, 3. Trace and Microprobe Techniques, 1 (J) (1582-1983) # 409 NEUTRON ACTIVATION ANALYSIS FOR ULTRA LO» CONTENT OF URANIUM 6-19 AND THORIUM IN ALUMINIUM AND SILICA i.Hitsugaahira. Y.Koma. M.Yagi. S.liirai*. I.Okada* Institute for Materials Research. Tohoku University. Sendai 980 Japan «Atomic Energy Research Center, Musashi Institute of Technology. Ozenji. Kawasaki 215. Japan It is well known that even the very low content of uranium or thorium in semiconductor materials Bay cause damages against the function of semiconductor by internal irradiation of a-rays. Therefore, to develope the preparative method for high purity semiconductor materials, it is essential to establish an analytical method for uranium and thorium with the highest sensitivity. Neutron activation method seems to he promising for the highly sensitive analysis of uranium and thorium. That is, uranium and thorium can be detected easily through **BNp and "'Pa. respectively. The two product nuclides are gamma emitters and the determination of uranium and thorium through the gamma-emission rates of aSBNp and "'Pa till be performed easily by the use of conventional gamma-ray. spectrometric technique. The two product nuclides have farely long half-life values and. therefore, long irradiation see*- to be effective to enhance the sensitivity. On the other hand, long eradiation inevi tab Ну produces interfering gamma-emitters and increases the simultaneous production of fission products from uranium and thorium. If the materials for analysis and the impurities contained do not produce strong gamma-emitters, instrumental neutron activation analysis (INAA) technique will be useful for the determination of ppb level of uranium and thorium. But. to attain the sensitivity of ppt for uranium and thorium by heavy or long irradiation, the chemical separation of "*Np and ***Pa becomes to be necessary. The main objective of this research is to develope a simple and conventional method to separate "**Np and "'Pa which is useful for the determination uranium and thorium in semiconductor grade of silica and aluminum. Re used two reactors for neutron irradiation, the TRIGA-II in the Atomic Energy Research Center of tfusaahi Institute of Technology and the Japan Material Testing Reactor1JHTR) in the Oarai Laboratory of Japan Atomic Energy Research Institute. The neutrons of TRIGA-II are well- modelated with the flux of about 10"n/cm'/sec and those of JHTH have considerable epUhermal and fast components with the thermal flux of 410 about IQ'4n/cmVsec. He соцЫ apply more than 1 grai of a sample to the irradiation fay TFUGA II but the amount of the sample for JMTR irradiation is Hinted to be about 50umg. Thus, the sensitivity in JNTR irradiation nas expected to be about SO tiles larger than that in TRIGA-II irradiation. The Majority of interfering fission products {FP) and activation products(AP) were removed from ж**Рв and *"Wp by anion exchange chromatographic method in HC1-HF mixed acidic medium. The out-line of the separation procedure is given in Fig- 1. The oxidation states of Pa and Np are adjusted by dissolution of the evaporated residue in SN HCi with a saall peace of Al to be V and Irradited sample IV. respectively- 1 It is readily found that 0-01—0.1 Dissolution.by cone HF soln. ppb of uranium and thorium can be 1 Evaporated to dryness determined iith high accuracy by neutron activation analysis iith I chemical Beprartion(РИАЛ) shown in I +300mg Ai Fig. 1- Unfortunately, no reliable 1 standard sample for ppt level of Dissolution in 9N HCI uranium and thorium is available. 1 Thus, we can only estimate the Doiex 1x8 maximum sensitivity to be 1 —lOfpt 1200 —400nesh) extrapolating the sensitivity found 1 in the experiment using a stadard FP.AP - 9N HCI gash sample for ppb of uranium and thorium. 1 It means that 10"'4grams of 9N HC1-5H HF mash uranium and thorium in aluminum and 1 2 silica are responsible in RNAA "Pa.»"Np by the irradiation with high flux reactor such as JHTR- Fig. Separation Procedure for ав, Nb. Zr. and their activation "'Pa and йр from the products are not reaoved from Pa and irradiated Al and SiOi Np fraction by the separation procedures shovn in Fig. Thus, long life fission products such as "Zr. and ecNb interferes the detection of the gamma-rays of ea,Pa and "eNp separated from samples irradiated in long period. That is. short irradiation in high flux reactor is more preferable than long irradiation in low flux reactor, because the relative yields of the fission products to '"Pa and "eNp are smaller in short irradiation. 411 THE DStEMCHATIOH OP SrOHSAKEOUSIX M33I0KISG ACTINIDE ACTIVITY BY| 6_20 BSUTROH COBRELATIOH METHOD I A.E.Konyaev, T.P.Koeitsyn. All-Union Research Institute of Inorganic Materials, Moscow, USSR nondestructive methods of actinide spontaneous fission activity determi nation are widely employed in measuring practice. They enoompaes calonmet- ri. ones and the methods, based on the analysis of the instantaneous у -ra diation of fission and time correlations of fission neutrons» The last are to be prefered due to a high penetrating ability of neutrons, rapidity and relative complicity of their implementation. The methods are being develo ped along the ways of both improving the measuring Mans to analyse neutron correlations and oreating the models that suet adequately describe the de pendence of a unit response on the activity of actinide spontaneous fission, the correct accounting of the affecting factors and a search of calibration procedures, providing the accuracy of determination without loss of rapidity. The moat optimised approaches to the standards system of actinide spon taneous fission activity are considered. The meirological characteristics of etalone standards of and z58Cf spontaneous fission activity In the range from 20 to г*10° 5k are presented. The statistical constituent of the error of the reference specimen calibration does not exceed 0.5% and is deter mined by the activity of actinide spontaneous fission in a specimen. The sys tematic constituent makes a decisive contribution to the total calibration error and is equal to 2-356 whioh is mainly due to an error in the determi nation of the half-life of the spontaneous fission of the principal nuclide. However, in some cases, when reference specimens are used that were certi fied from the activity of the spontaneous fission of actinides having a si milar composition the systematic error of their certification may not be taken into aooount, A calibration procedure is suggested for neutron coin cidence units using reference specimens. Models have been developed that must adequately describe the response of measuring units by the iionte-Carlo method in different approximations taking account of the real distribution of the multiplicity of the neutrons of actinide epontaneoue fission and the influence of the effect of multiplica tion in the proper neutron field. Alao, for the specific types of composi tions analysed approximate models have been developed that make it possible to derive calibration dependences as analytical expressions. The service abi lity of the developed models has been shown experimentally. Different consti tuents of an error have been estimated. Specific examples are gives of the realization of the developed methods as applied to fu metal and oxide specimens of different isotopie compositi ons, mixed U-fu oxide fuel ИОХ-type as mil as isotope productions on 23SPu dioxide and ' Of base. The feaslbllty is discussed to determine the activi ty of "da spontaneous fission. The relative error of determinatlor actinide spontaneous fission activity varies in the range from 0.1 to 3,0$ depending on a compound type, iaotopic and chemical compositions etc. 412 DEOTROH METHODS OF ACTIHIDE ASSAY ADD THEIR IETRO10GIC SUPPORT I 6-21 A.E.Koayaev, Y.J?. Koaitaya, V. S.Pedorov. All-Union Research Institute of Inorganic Materials, Moscow, USSR Recently nondestructive methods of actiniae assay (primarily U, Pu and transplutonlum elements) nave been under Intensive developnent. They are ba sed on registration of intrinsic neutron radiation resulting from spontaneous fission events and { The paper outlines the measuring complex of the working standard of a neutron flux unit VET 10-5-86 in the flux range of 102-5» 10 s-1 and neutron energies from 0.3 HeV to 14.6 HeV based on standard radionuclide sources of the 238Pu-P, 238Pu-Li, ZAOta, 25Z0f, 238Pu-0 and 238Pu-Be types as well as SBN-1 spectrometer based on a stilbene monocrystal with the J" -background discrimination according to a pulse shape and comparators-radiometrlc units with a well type neutron detector. The error of the standard source certifi cation is 1.5-2. OSS at the confidence level of 0.99. The methodologlc error of the transfer of a flux magnitude quantity by comparators does not exceed 0.5%. Spectrometer SBH-1 is used to analyse the spectra of standards and compositions and if there is a difference, corrections for the efficiency of the registration of measuring instruments are Introduced. The differential error of the processing of the reooil proton experimental speotrum and the recovery of neutron spectra is 10-15%, whloh makes a contribution of no more than 0.5% to the total error of the flux measurement. Thus, neutron methods make it possible to determine aotlnides in different compositions and in waste with an error of 2-3S and 15-20%, respectively, at the confidence level of 0.95. 413 A METHOD FOR HYDROGEN CONTENT CONTROL OF IK>2 FUELS 6-22 O.K.Timonina, B.K.Zuev, B.F.Myasoeuov. Vernadsky Institute of Geochemis try and Analytical Cheralatry of the Aoaderay of Sciences of the USRR, Moscow, USSR N.E.Babulevieh, S.S.Yakiraov. Kurchatov Institute of Atomic Energy, Moscow, USSR Among impurities in ШК ceramic nuclear fuels, H„ content is an important quality feature. The total content of hydrogen (both molecular Hg and that from hydrogen containing compounds) in U02 fuel must be closely controlled to avoid damaging of the fuel element cladding tubes under the action of hydrogen released from UCU pellets in operating reactors of nuclear power stations» Currently used methods for H2 determination in UOg pellets are complicated and labour-consuming, e.g. vacuum extraction method with masa-spectroraetric detection [ij or ion chromatography with thermal conductivity detection [[2] . We have proposed a rather simple and fast Hg determination method which provides means for determining H2 content independently from its chemical form in the surface layers of the pellet and receiving the hydrogen concen tration profiles* The analytical method is baaed on laser microsampling in the inert gas flow. The depth of microsampling is about 500 m. The diameter of craters formed under the action of the laser beam in the chosen microregion is 400- 500 m with microsample volume being about 5x10 enr as considered equal to the crater volume* The gases released from the melted and evaporated microregion of the pellet into extraction cham'car are carried away by the inert gas flow to a detector* The hydrogen content can be detected in two ways. In one analytical procedure the analyzed gas mixture is transported to a separating chromatographic column and then to a solid electro!it cell (SEC) possessing practically uni-polar oxygen-ion conductivity and working in coulo- raetric mode* Hydrogen content in the microsample la determined by titration from the amount of used oxygen ions [3]. In the other analytical procedure hydrogen content is determined by means of the semiconductor gas sensor based on metal-insulator-aemiconductor (MIS) structure of Pd-SiO£-Si type £4], amount of hydrogen in the microsample be ing measured from the ahift of MIS voltxfarad characteristic whtoh is con ditioned by kinetics of hydrogen adsorption. The.both analytical procedures allow to determine the total hydrogen con tent independently from its chemical form in the pellet since under the ac tion of the laser beam KgO molecules decompose with H« release* The diagram of the setup as it was assembled for realization of the pre sent method is given in Fig. The use of a laser functioning both in single pulse and multipulse gene ration mode allows to carry out single local H2 determinations (for study ing H2 distribution in a pellet) as well as determinations of average H2 414 content in the pellet (while laser functioning in multipulse generation node at a frequency of about 20 Hz with pellet displacement)• 0Н5°НШЗ- dTromatooraphlc № coLumn extraction chamber N T- SECJ-^- sample MIS U0 2 SEKSOR . COMPU- 1 - T6R Pig. Schematic diagram of the setup for the determination of II, d content in U02 fuel pellets The setup allows to carry out -comparison between analysis data received by two independent transducers. The investigations didn't show considerable systematic discrepancy between the two ways of detection. The analysis time in case of a single determination amounts 2-3 minutes for the SEC with chromatographic column and about 30 seconds for the MIS. The limit of detection with the both meana of analytical signal registra tion is about 10" g H?. Relative standard deviation Sr of the local deter mination series for homogeneous UO- pellet doesn't exceed 0.2. References 1. Andrievsky R.A. et al. //Atomnaya energiya. 1981. Vol.51, M.2. P.129. 2. Dams '«. et al. //J. Hucl. Mater. 1968. Vol.153. P.10B, 3. Zuev B.K.,Bogdanov А.Л..Tiraonina O.K. //USSR Patent, sir 126144-5. 1987. 4. Lundstrom I.,3vensson Ch. Solid state chemical sensors* Acad. Press Inc. Janata and Huber. 1985. 415 A METHOD FOR DETERMINATION OF HYDROGEN CONTENT IN URANIUM 6-23 DIOXIDE SAMPLES USING SEMICONDUCTOR SENSOR N.r.Zvereva, S.D.Lazarev, N.E.Teterln, V.I.Fillppov, S.S.Yakimov, V.Ya.Goncharov. All-Union Research Institute of Inorganic Materials, Kurchatov Institute of Atomic Energy, Moscow, USSR The physical and chemical properties of uranium dioxide (UOu) ceramics are easentialy affected by the content of impurity hydrogen (H^), Thie prob lem becomes especially Important in connection with well-known technical ap plications of this ceramics. Separation of Hg from the U02 ceramics when the latter is used at real Industrial enterprises must be taken Into account to en sure their normal operation conditions. Currently the Hg content in UO* samp les Is determined using vacuum hot extraction and ion chromatography method, mass-spectrostetry method, coulometric method. All of them are time-consuming, require sophisticated instrumentation for their application or are low-sensi tive. In the present work a diagnostic method for determination of the H, content in U02 samples is developed. The method is based on use of small gas-sensiti ve sensors* A metal-insulator-semlconductor (MIS) structure of Pd-SiOg-SI-ty pe was used as the sensor. The structure was manufactured on the basis of mi croelectronic technology on the silicon crystal and had the dimensions 2x2x0,4 mm* When H2 is adsorbed on the catalytically active Pd surfaoe with subsequent diffusion to the metal-dielectric interface the structure capaci tance changes and this is registrated by the electric Instrument* The sensor had been calibrated on the gas-dynamical mixing facility which permitted desi red volumee of gas mixtures with different Hp concentrations to be produced. The sensor permitted the H« concentration to be reliably measured in the cham ber filled with a noble gas within the range 0.1-100 ppm, the characteris tic time of the аепзог*8 response depending on the H2 concentration and not exceeding 30 s. The gas-aeoeitive sensor temperature was chosen within the range 20-150°C and was specially thermostab!11zed. The sensor's gate, made of palladium, provides a high H2 selectivity. The facility for determination of H2 In U02 samples (with a mass of 5g) Included a high-temperature furnace where a beryllium dioxide ampoule with the sample was heated up to 1600°C. The gas releasing from the sample was accumulated in the chamber with the gas-sen sitive HlS-sensor set Inside It. The U0~ sample was previously outgassed by heating up to 300°C in vacuum. The measurements were carried out at sample temperatures of 400°C, 800°C and 16CO°C. The amount of H, released frot» the sample, determined from these measurements, Is equal to 8 ppb (mass) at T • 400°C, 32 ppb at T - 800°C and 102 ppb at T • 1600°0. In an independent experiment performed using the standard coulometric method the amounts of H2 released from a similar U0„ sample were measured at T • 800°C. The results ob tained from these measurements agree with the above data. It should be noted 416 that the amount of Hj released from the U02 sample at T • 1600°C me found to bo higher than that at T • 800°C. This faot is worth being studied separately. Xbe method for dlagaoatlos of the Hg oontent in item*' manufactured of V02 using semiconductor sense» aen be used, when somewhat Improved, for control of Industrial produots In nuoloar fuel fabrication. X high sensitivity reached using the new methods (minimum amount registra- ted Hg 10"10-1o"11g), its elmplloity and high sensitivity make it possible to use it extensively for determination of small quantities of gases dissol ved in aotlnlde ooapounde. 417 27.3ак.1607 DETERMINATION OP ACTINIDES ADMIXTURES IN URANIUM AND PLUTONIUM 6_2+ A.I.Karelin, V.I- Astafurov, V.D.Belyaev, V*I0Turkin, 0.P.Lobaa,V.V.smirnov Folytechnlcal Institute, Tomsk» USSR The report treats radiochemical and physical-chemical methods to determine thorium, neptunium and plutonium admixtures in uranium and thorium, uranium and neptunium admixtures in plutonium. Determination of Plutonium in uranium.The analized sample ie converted in to a nitrate solution,plutonium is stabilized in the oxidation level +4 and its extract-chromatographic isolation is made on the column with methyltrio- xilammonia nitrate (TOMAN) on the inert medium. After elution plutonium is electrically precipitated on a base out of stainless steel and alpha-spectro- metric analysis of the received specimen is made. With the sample mass of 1 g and time measuring сГ 1 h the lower limit of determined plutonium content is 7x10"*9#. There have been worked out some variants of this method with radio - metric finish ( the count of alpha-particles without deviding them according to their energies) and with isotope dilution. The ways of deep plutonium cleaning from uranium and thorium nuclides are proposed. Determination of neptunium in uranium. The analized sample is converted into a nitrate solution, neptunium is stabilized in oxidation level +4 and its extract-chromatographic isolation is made on the column with TOMAN. The quantity of neptunium in the eluate is determined with a spectrophotometry method* measuring light absorption of Up(IV) complex with arsen-aso indicators III or with a radiometric method. With the sample mass of 0.5 g the lower li mit of determined neptunium content is respectively 4-эсЮ % and 1x10" %,Elec- trochemical methods for determination of neptunium without its beforehand ex traction out of the analized sample are tret ted. When using changed poten - tial coulometry method the lower limit of determined content is 5x10 %, Determination of uranium in Plutonium.The analized sample is converted in to a hydrochloric acid solution, plutonium is stabilized in oxidation level +3 and extract-chromatographic isolation of U(VT) la made on the column with TAA. The uranium quantity in the eluate is defined with a spectrophotometry method in a medium of buffer solution, measuring light absorption of U0 complex with arsen-aso indicators III. With the sample mass of 0.1 g the low er limit of determined uranium content is 2x10~^%o There have been offered methods of direct spectrophotometry determination of microgram uranium quan tity in metal concentrates. While determining uranium in plutonium concentra tes we measured optical density of a solution in wave length range 810 ran ( the plutonium absorption proper in oxidation level +4) and 650 nm С the plu tonium absorption proper and absorption of Uo|+ complex with araen-аво indi cators (III).With the plutonium mass in a solution of 50 mg the lower limit of determined uranium content is 0*01%, Determination of neptunium in plutonium,of thorium in цтятИчт and pluto - ,.<2& nium. There have been considered radiochemical and physical-chemical methods for determination of neptunium in plutonium,of thorium in uranium and pluto nium, the characteristics of these methods are compared, the ways of selec tive extraction of determined elements out of uranium and plutonium solutions were offered. 418 DETERMINAIIOH OP РИЛОИ11Ш IH HIGH-ACTIVITY SObUMOUS Г1-25 B.F.Gromov, H.V.2akharov, V.I.Astafurov, A.A.Vashman, L.I.Moseev. Physical Snergy Institute. Ail-Union Research bistltute of Inorganic Materials, Moscow, USSB The paper discusses physioo-chemlosl and radiochemical methods of Plutoni um determination in high-activity solutions, compares the characteristics of the methods, gives recommendations on their usage in practice* Method of "tffi'W"1 p"tyt^al coulometrv (CPO). 'the main difficulty that faces the analysts using the CPC method is to have low background ourrents and retain high and reproduoible values of an analytical sign.*!. The techni que of sample pretreatment presented in the pa^er makes it possible to over come this difficulty and use the CPC method for the dlreot determination of Plutonium in nigh-activity solutions. Large amounts of Ih, U, 2r, Al, alkali and slksll-earth metals, yrecent in as electrolytic cell do not interfere with the analysis» The found out eequenoe of an electrochemical treatment of a sample, pre-eleotrolysie of plutonium and a potential change makes it pos sible to remotely determine plutonium in spent nuolear fuel solutions and effluents. Snectronhotometri с methods. The paper considers up-to-date methods of Plu tonium determination with spectrophotometry deteotion that are used in the practice of analytical laboratories. Conditions have been studied for stabi lisation of plutonium forms being detected. A spectrophotometry method has been suggested to determine plutonium in its concentrates by Pu(IV) light ab- aorption in a buffer solution, containing ammonium diethylenetriaminepenta- acetate. Magnetic resonance and matmetoohemioal methods. In solutions without pa ramagnetic impurities plutonium valence and concentration oan be determined from the data of high resolution HHR-speotroaoopy, nuolear magnetic relatat- ion and magnetoohemioal measurements. Plutonium ions of different charges can act as shifting or relaxation reagents that influence the ehemioal shift and relaxation of dissolvent moleoules and define the solution susceptibility Radiochemical methods. To improve the selectivity and aoouracy of determi nation of low plutonium contents in high-activity complexly composed solut ions it is recommended to oombine the methods of isotope dilution, extract ion chromatography and alnha-epectroaetry. Seep purification of plutonium from alpha-emitting nuclides of other elements makes it possible to measure Plutonium by a radiometrio method (alpha-partiole counting without separat ion according to the energy). Comparisons are made between the coefficients of plutonium purification from amerioium and fission products using different techniques of plutonium extraction from high-activity solutions. Methods of Plutonium extraction and purification. She paper presents the results of the investigation of solexea of different types designed for se lective isolation of plutonium from high-activity solutions and separation of its valent forms. 419 DETSUGKAOTON OF ОДГ-НВТЛЪЫС IMPURITIES IH SOLID ADD ПОЛИВ 6 86 ACTUraDB-COHTAHTtBG MATERIALS SI IOH-EXCHABGB СЖОМАШЖАИЯ I- I АШ) 6AS OBKOJIATOSIUHHY T.I.Evaeeva, H.A.Zemlyanulthina, T.Xu.Chepohugova, T.A.Keruohenko, I.V.Iavlova, I.L.Foletaeva, B.S.Valyunln, A.H.Rybin. All-Vnion Research Institute of Inorganic Materials, Moscow, USSR The results of simultaneous determination of chlorine, fluorine and sul- pbur or oarbon and lulphur oontents (In the amount of 0.1»1)W In metals and uranium, Plutonium and thorium oxides aa «all as In solid and liquid oomplex materials containing transuranium elements ore presented. The techniques are baaed on the prinolple of preliminary separation of im purities from the material base during pyrohydrolysia or thermal oxidation In a stream of gas (oxygen, air, etc.) «1th subsequent condensate or gas mix ture analysis by two-column ion-exchange chromatography with oonduotoaetric detection or by gas chromatography (carbon dioxide and sulphur dioxide de tection by thermal conductivity). In ion-exchange chromatography (the chromatograph "Tevet 3906") the 200x4 mm separating column was filled with anion sorbent X KC-I «1th 0.025- 0.040 mm particle sices and having the exohange oapaclty of 0.03±0.01g/eq/cn/, the 100 i 6 mm suppressing column «as filled with catlonlta КУ-2ХВ4С. Sa?CO, (0.003 mole/1)-HaHCO, (0.0024 mole/1) «as uaed aa an eluting solution. In gas chromatography polysorb-I was used aa a sorbent. The conditions of fluorine, chlorine, sulphur and carbon quantitative separation from the in dicated materials have been determined. The pyrohydrolysia behaviour of alkaline-earth elements, strontium, ce sium, aluminium, niolrel, Iron, chromium (III), manganoze (II), ruthenium, zirconium, molybdenum and some rare earths baa bean studied. The results for fluorine, ohlorlne, sulphur and carbon in the amount of 0.1-1% aa determined by the above techniques are compared with the results of eaoh component in dividual determination by spectrophotometry and coulemetry or using ion-se lective electrodes. The model of a high temperature sample decomposition device has been work ed out. The + 'chniques are shown to ensure the precision of the results of measu rements. Confidence limits for random, systematic and total errors In the results of the impurity determination are found and evaluated. 420 IN-LINE AND NON-DESTRUCTIVE DETERMINATION OF TH, U AND PU, IN PROCESS STREAMS, AIR FILTERS, AND MOX-PELLETS 6-27 P. Hoffmann, N. Pilz, K.H. Lieser Fachbereich Anorganische Chemie und Kemchemier Technische Hochschule Darmstadt, D-6100 Darmstadt, FRG For in-line tnd non-destructive analysis XRF was proposed. The determination of the actinides by excitation of the K- lines by suitable radionuclides has several advantages : - no interferences with other X-lines in the spectrum - examination of great volumes by deep penetration of the K-lines of about 100 keV, - construction of a compact experimental device, - stability of the excitation intensity and of the measuring conditions. An experimental set-up consists of an excitation source, the sample and a suitable detector. For each analytical problem such a set-up can be optimized with respect to the following points : - decay mode, radiation energy, half-life, and radioactivity ot the radionuclide, - position of the sample, - suitable detector, - angle source-sample-detector. For the determination of Th and U in laboratory air filters a system was used consisting ot a Co source, a well col- limated sample position, and a HPGe-detector in an geometri cal arrangement with an angle of € 30 . The control measurements of various actinides in nuclear 1 33 process streams can be performed using а Вя source, directly fixed at the sample tube, and a HPGe-detector at an angle of about 45 . The u- and Pu-content in MOX-pellets and fuel rods can be determined using a high-radioactive (fc 10 Ci - 370 GBq) 1 QV Ir source, a narrow collimated and strong shielded sample position and a HPGe-detector of 13 mm thickness. Calibration curves were constructed, lower limits of detection were determined and reproducibility was chequed. nrrasiiSAiioHs o; THE SEPARATION OP нр, Ра, и, ть АНВ КЕБ ш ВЕОЬОСКАЪ B.Qlelsbsrg, B.U.Itf, B.Qorski. Joint Institute Ют Nuclear Research., Dubna, USSR The quantitative detexeAnation of trace amount» of Hi, О and EBB In very depleted reeks le necessary to get Information about geaetio ргоооевев in the investigated area. 0, Hi and BBS are used ae geoohemloal Indicators. On tbe other band, the Imowledge of the contents of them elements In natural materials le of Importance when they are rich enough for their use as raw materials. We treated two types of geological samples which differ considerably in their origin and in toe 0, la and BBS contents. BBB, V and Та oonteats in geological samples material I II Element Perldotltio reokm/l/ Bastnaesites СЯ Uonazites/3,47 3-15 ppm 73-76* 56-75* XI 0.04-0.8 ppm 0.02-0.1* 0.02-0.35* Th 0.15-0-7 ppm 0.1-1* 0.5-10* It is clear that the analytical methods and chemical separation procedur es should Ъе тегу different for these two types of materials. I. Ihe first part of our work represents some methods of radiochemical neutron aotivatlon analysis used for the determination of D-, Tu- and HEB- traoe amounts in peridotitio rocks and meteorites. The tracer nuclides of BBS, of 3*Rp and "Pa are separated from the interfering isotopes result ing from the great amounts of 7a, Or. Hi and Oo and from Sc-microanounts. The first method luvalves the selective sorption of BEB by cation exchange from a HOl/HjOgO^-solution. Up and Pa are extracted after passing cation exchange resin from 6H HBO, with ЮЮ-eyclohaxan /1?. The chemical yield of RBB was monitored using ^ and 1**0e and the Dp yield was observed according to In the second part of work which we used for the separation of such samples it is possible to oohieva an efficient purification of the REE fraction in a one-oyole prooess 0/- By extraction chromatography with TOPO in the presence of completing agents we can accomplish the separation of the ВВБ from almost any element eontalned in nacrooonoentrations and also from mlcrcamounts of Th, Pa, О, Яр and Sc. II. Baetnaesltes and mona&itae are very rich in light BEE. The IH&& of some bastaat*ltea allowed only the determination of the La, Oe, Bd, Sm, Bu end lb oontente. The analysis of Tm, lb and Xu in such samples requires their separation from matrix components and from large amounts of light BBB. Tery convenient is the use of extraction chromatography with HDBHP. For using this method the preliminary separation of V and Zh from the -RSB fraction is neoessary. the separation involves the sorption of V and Pe by 422 anion exchange the precipitation of ВДВ and Xh and the sorption of Ih either on a TOPO- or HDBHF-oontalnJng oolunn. The behaviour of II and Hi during the separation steps is observed using X-ray fluoreseenoe analysis. Particular investigations aimed to stud; the sorption and desoiptlon of V and Hh by the eitraotante used were controlled hy the " Tb and "u produced by "o"-irradietion on the microtron MI 25- References 1. B.Gleloberg, S.Hieae, f.Kramer. Chea. Erde 47 (1987). pp. £31-242. 2. B.eielesere, Zfk-Roaeendorf, 1987. 3. D.I.RyabchDcov, V.A.Ryabulchin. "Analytical ohemistry of rare-earth elements and yttrium" (In Hussian), Haul», Hoaoow, 1966. 4. K.Halgorelty. H.bevequo. Scienoes et techniques 1978, 32, 19-27. 5. B.Ooraki, Xu.S.Eorotkin, T.K.Xosyakov. Journ. ox Badlosnal. Hucl. Слот., (Articles), 121, 1 (1988) 73-81. # ^^.v^ij*»". STUDY OF URANIUM DISTRIBUTION IN BLACK SLATE SAMPLES 6-29 E.S.Flitaiyan. Institute of Nuclear Physics, UaSSR Academy of Sciebcee'," Tashkent, USSR Many geologloal phenomena, e.g. ore formation, were revalued ae a result of the intensive radiogeocherniatry development In the 60-fl. The elaboration of the local analysis methods for uranium and therium in our country and abroad [1,2] contributed a lot to the geological knowledge of the lavestiga-» tors. This research based on the registration of spontaneous and forces ura nium and thorium fieeion fragments elevated considerably the detection limits for these elements in a sample studied without breaking the natural associa tion of minerals. It is this factor that ensured the success of radiographic methods in geology and geochemistry. The method based on the registration of the О fission products in tbe process of neutron irradiation by an external track detector that ie placed close to the object studied has been used fur the radiographic analysis of the elate samples of a well core crossing the horizon studied. The detection limit of this method is restricted by the detector racistion resiatanoe and it makes 5*10 'g for lavsan film and 10 7g for mica. As a result of selective etching on track lavean detectors, only uranium and thorium fission products can be detected. However, thorium contribution may be neglected if its con centration dues not exceed that of uranium by more than 3 orders. The peculiarities of uranium dynamics end concentration process in slatea have been studied alongside with the determination of probable channel forma- tion connection with the regularities of the conventional mineral formation. The local analysis of the ore admixture concentration allowed the establish ment of its distribution pattern between the mineral phases and thus the evaluation of uranium bonding strength In rocks. The uranium admixture distribution pattern in slate samples of various metamorphlsm development degree haa been analysed. Estimation of uranium distribution pattern and its mode of occurrence allowed the solution of some genesis problems, in particular, it gave birth to the theory of the step-like dynamics in uranium redistribution in the preceding ore forma tion proceee[3j. References 1. Fleischer R.L., Priece P.B., Walker R.M.//J.Geophys.Ree.1964. Vol.6ft, N 122. P.4885-4889. 2. Flyorov G.N», Berzina I.G. RadiograpMa mineralov, gornikh porod 1 rud, M.:Atomiadat,1979. P.223. 3. Ermolayev N,P., Kist A.A., PI itstyил E.S.et al. Yavlenle etupencbatogo kontsentrirovania elementov prl obrazobanii rud v chernlkh slantsakb. Geologia rudnlkh meatorozhdeaii. 1933-N 3.P.86-91. 424 ACTINIDES IN ENVIRONMENT ACTIBTDE BEHAVIOUR IH HATURAL WATERS I—~—I Oregory R. Choppln, Department of Chemistry, Florida State ' university Tallahassee, Florida 32306-3006, USA The potential range of chemical reactions of aotinlde elements in natuial systems le unusually broad. This ia due to the existence of these elements in one or more of four different oxidation states, each with a different set of values for cosplexation. Hydrolysis, camplexation by carbonate, complexatlon and/or redox by hum!с materials, etc are the types of reactions which re sults In retention vs. mobility of the actinifaa in natural waters, For ex ample, if plutonium Is In the IV state, hydrolysis is dominant and leads to high sorption on solids, oolloids, etc.However, in the V state, Puo|, hydro lysis and eomplaxatlon is minimal and mobility should be high. Model calculations are presented to show the speeles expected In several, typical, natural water's. The quality of the data is discussed in terms of the implications to the geochemistry of the actinides. The preparation of this paper was assisted by a grant from the USDOB-OBES Division of Chemical Sclenoes. ACTINIDES IN THE BNVTROIOIENT Г"T~, j K.H.Lieser, R.Hill, U.Muhlonweg, Th.Steinkopff, Tu Shu-de, Fachberelch Anorganisobe Chemle und Kernehemie,Technirjche Hochschule Darmstadt, D-6100 Darmstadt, FRO The behaviour of actinides in the environment is governed by complexation, hydrolysis, colloid formation and sorption. The most important natural oomp- lexing agents are carbonate and humlc substances. The stability of 1:1 car bonate complexes of aotinides is decreasing in the order H** •> Mo|+ •> M'+5C «Hot. If the concentrations of the humic •substances are relatively high (e.g. in rivers and in the upper layers of the ground), complexes formed with these substances play an Important role. Hydrolysis leads to the formation of by- droxo complexes which exhibit high sorption ratios. At very low concentration U: 10~5 mol/1) polynucloar hydroxo complexes and intrinsic colloids are not formed, but sorption on carrier colloids Is preferred. Representatives of all relevant oxidation states at the actinides are in vestigated. In absence of high concentration of complexlng agents the beha viour of Ao'+ and of lb is governed by hydrolysis and sorption of the hy droxo complexes. Consequently, sorption ratios due to "hydrolytic adsorption" are relatively high. Carrier oolloids are of major Importance, in particular in groundwater of low salinity. KpOj is relatively mobile and the sorption vatioa are relatively low. At low redox potentials, however, Hp is formed which is Immobile and strongly sorbed. Experimental results for Ac'*, Th , HpOj/Bp and U0|+ are presented and discussed. THE BEHAVIOUR U? TRANSURAHIUH ELEMENTS in ТКЯ ENVIROHMENT 7-3 F.I.Favlatskaya, T.A.Goryachenfcova, B. P. Myasoedov Vemadsky Institute of Geochemistry and Analytical Chemistry of "\\e USSR Academy of Sciences, Moscow, USSR She transuranium elements (TUE) are important ecological long-term radio nuclides forming the human doses (human body) during long time after their environment entrance. In this review the sources and forme of TUB entering* distribution of these elements in the components of the surface blogeozeno- ses, the forms of their occurrence and the peculiarities of their migration in soils, accumulation in plants are considered. Falling from the atmosphere TDS are included in the biochemical cyclic migration with the following redistribution In the ground surface. For examp le, it was established, that in the geochemicelly linked elementary landsca pes and soils Plutonium distribution is independent in its source of penetrat ion and is determined by their location, soile type and their genetic struc ture, plant type as well as by other natural factors. The maximum concentrat ion of plutonium In soils is found on water-shed and on decreased element of landscape, the minimum one - on the slope. The common regularities of the distribution of plutonium in soils in various natural ones are: 1) concen tration in turf or litter with the gradual decrease of plutonium content with depth; if they are poor, it's ooncentrate at the top part of humus hori zon A; 2) carrying out of eluvial horizon A2; 31 secondary accumulation at the top level of llluvlal horizon B; 4) more even distribution on the profile of hydromorphoue and ploughed field soils. It is known, that decreased ele ments of landscape and llluvial horizons are the geochemical barriers on the way of oarrying out of chemical elements and radionuclides. Two types of Plutonium transfer is soils (prevailed slow and fast) are established; the coefficients of migration are calculated; estimating long-term prognosis of plutonium migration to depth various types of soils are given. The depth and intensity of migration increase in soils of more light mechanical composit ion and containing IOBS quantity of organic matter? chernozem <£ forest grey < soddy podzollo and sandy. TUB accumulation in plants depena on the type of soil and forms of ele ments occurrence in the soil, type of plants, conditions of their grow etc The concentration ratios of TUE in plants and soil are fluctuating in wide intervals (10-1). The been plants accumulated TUE more strongly than ce reals, vegetative organs more intensively than generative one. The concent ration ratios TUE in the plants, growing in field condition are several or ders higher than in model experiments because of deposition the radioactive aerosols and the particles of polluting soil on the surface of plants. The retention of TUE in overground parts of plants and their migration to the other organs are caused by the form of radionuclide deposition, zlse and solubility of particles, agrometeorologioal and other natural conditions. The intensity of accumulation of TUB in plants increases in the range: Pu с Am, Cm « Np. TUE in soils can exist in different forms: water-soluble, exchangable and lightly soluble, mobile, amorphous and silicate ones. Quantitative corre lations between them are caused first of all by the sources and the forms of 427 entering of these elements, physico-chemical composition of soils and property of radionuclides» The content of more mobile water-soluble and exohangable forms of Am and Cm several times more than Pu, Np. TUB are accumulated very quickly in soils and great bulk of Pu (96-98£J and Am(B530 is found in amor« phous compoundSs covering mineral specieB in film forme* Distribution among aeparete amorphous compounds depends on the types of soils. In first surface film (free humus acids and their compounds with chemical elemented content of Plutonium increases in the range: turf podsolic < grey forest < leached cher nozem (311 37 and 5456)* that correlates with the quantity of humus and ex- changable calcium in soils. In the next film (of hydroxydes iron and alumi nium? plutoniua content changes in inverse order (67, 59 and 43&)» that cor relates with the quantity of hydroxydes. Tbe low Plutonium content in mineral fraction of soils (< 1%)) indicates, that plutonium penetrates slowly in cristalllne lattice of soil minerals* Plutonium was found in all components of organic part of soils: humus acids, low molecular acids, their compounds with chemical elements and others. Distribution of these components is caused on the type of soil» and mainly on quantitative and qualitative composition of its organic BUDgtanoes f\J. On one hand, low soluble humio acid, humatee and hydroxides increase accu mulation and stability of plutonium bond with soil, followed by decrease of Plutonium mobility and its concentrating in humus and illuvlal horizons. On the other hand, organic compounds promote plutonium transition id mobile state and increase its mobility due to formation of negatively charged com plex compound with fulvic and low molecular acids, depositing in soil with the products of metabolism and destruction of plant and soil mtsofauna residues* The prevailed slow transfer represents plutoniua migration in high dis persed partioles during soil washing with atmospheric falloua and with solid run-off* Plutonium occurs there in composition of humic acids, humatee with calcium, humates and hydroxides with iron and aluminium (part of plutonium can migrate as oxide when it enters on ground surface in that form). Fast transfer of plutonium is caused by migration in the composition of soluble complex compounds of iron and aluminium with fulflc- and low molecular acids* Reference 1. Pavlotsteya F.I., doryacherikova Т.Д. // Badiochemletry. 1987- Vol- 29. P. 99. 428 OH THE EXISTENCE OP ACTHflBES Ш GALACTIC COSMIC HAYS f 7-4 Y.F.Ferelygin, S.G.Stetsenko, Joint Institute for Nuclear Research; ' Dubna, USSR H.J.Crawford, I.J.H.Syaons, Lawrence Berkeley Laboratory, Berkeley, USA The experimental study of fossil tracks due to the heaviest Galactic cosmic ray nuclei in meteoritic olivine oryatals has been performed at the Laboratory of Nuclear Reactions, JHJR, during 1980-1987 in order to identify anomalously long tracks from the Z#110 nuclei '1>2'3'. The crystals from the meteorites-pallasitea Msrjalagti and Eagle Station were used. Before etching, these crystals were annealed at 430°C during 32 h. Such a severe annealing procedure provided the complete elimination of a Pe group track background of 101 -1011 tr.om"-3 and also the reduction of the etchable track length and smoothening the track length spectra for cosmic ray nuclei with 2^54 СЯ The semiempirical dependence of the volume etchable track length 132, on atomic number Z was based on only one experimental point far Xe5 4 L=26.5±2.5 urn. In the first experiment '•^ in the track length spectra obtained under these annealing conditions (Fig. a) one can see the track groups at 120-140.urn, 190-220 um. /1/ These groups «ere attributed *•••* respectively, to Ft-Fb and Th-U cosmic ray nuclei; in addition one anomalously long track I»365 urn, has been found. In a f'lrther Btudy ^*, the number of tracks with L*-210 um exceeds 1100, and the number of tracks with L-S350JUD reaches 10 (Fig.b). As one can see from (Pigs, a, b)the groups with track length of 120-140 um and 190- 220 ^UD are clearly divided. This ia obviously due to the lack of sufficient ly stable nuclei in the region from Bi to Th (T-^g* !°5 years-). She anomalously long tracks exceed by a factor of about 1.7 the mean track length 210 fan, attributed to ТИ-и nuclei • The last circumstance is very interesting in connection with the hypo 400 thesis about the existence of superheavy elements in nature. But for solving the problem of identifying the C.R. nuclei tracks with L=-210 um and to clarify the k!00 origin of tracks with Lj>350yim it was necessary to calibrate meteoritic olivine crystals with Au, Fb and U nuclei accele rated to energiee-j>25 HeT/n. The first experiment of this kind was carried out ct the Bevalac accelerator (LBL, Berkeley) in November 1987. The energy of ^TT nuclei was *30 and «70 HeV/n, the angle of incidenoe was 25° and, for some cry в tale, 10» to the 300 L„. polished olivine surface. The fluence 429 of 2**8u was about 10 cm" . The annealing, etching and track measuring 2 procedures were the same, as in previous experiments />» /. тде results of track measurements in 83 crystals in the MarjalaJvti meteorite are shown in Fig. 5i the maximum of the track length spectrum corresponds to 230±25_nm. Both the shape and half-width of this spectrum agree with those for "fossil" track group 210-20 Jim In length (Figre. a, e). Some systematical shift by about 10$ of the mean track length In the 3^J spectrum could be explained by periodical heating during 180 M.Y. radiation age of the Marjalabti meteorite. It is necessary to point out that for 32 olivine crystals from Eagle Station pallasite one can see rather good incidence of the track length spectrum for ^su and the corresponding group of "fossil" tracks k 220 jm and = 210 Jim). The longest track in the 238ц spectrum has a length ox up to 350-370 31m their abundance is 2% of the total number of tracks in the spectrum that is nearly the same, as the abundance of the longest fossil tracks* But the analysis cf the crystals containing the longest 23% tracks shows that these tracks oriented very closely to the main crystal planes of the olivines. This does not take place for % 350 ^un fossil tracks- Thus, the problem of the origin of the longest fossil tracks still remains unsolved and needs further more detailed investigations* Basing on the results of this calibration experiment» one can confidently conclude that in paper *"•' there were first presented the tracks from galact ic cosmic-ray actinide nuclei. The calibrations of olivine crystals with 8U nuclei first provide a quantitative basis for a new method of investiga ting galactic cosmic-ray nuclei (Z>50) by studying fossil tracks in extra terrestrial crystals. This method surpasses in sensitivity all other known methods. References 1. Perelygin V.P., Stetsenko, S.G./felsma ZhEMV 1980. T.32.S.622. 2. Perelygin V.P., Stetsenko S.G., Plerov G.N. Rapid Comra. JINR Ко. 7-85, Dubna, 1985. p,5. 3- I&agvasuren D., Otgonsuren o.. Perelygin V.P., Stetsenko S.6.. Jakupi В., Fellas P., Perron С Solid State tfuclear Track Detectors /Ed* Francois et al. Fergamon Press. 1980, P. 997* 430 APPLICATION OF ACTIVITY RATIOS OF ACTINIDES IN THE 7-5 ANALYSTS OF ENVIRONMENTAL SAMPLES Ursula Niese*, H. Smulek**, M. Borkowski**, W. Helbig* * Central Institute of Nuclear Research, p.ossendorf, P.O.Box 19, Dresden 8051, GOR ** Institute of Nuclear Research and Technology, 03-195 Warszawa, Oorodna 16, PL Determination of actinides in environmental samples are necessary because of their long half lives and radiotoxicity. The occurrence of these elements in environment is a consequence of nuclear wapon tests, accidental releases from power stations or effluent discnarches from plutonium handling and processing facilities. Activity ratios can generally be usee; for identification of the source of radioactive contamination taking into account that the isotopic composition of the possible sources ere significantly different /1,2/. Especially in such cases, where the background of long lived nuclides is known. We have investigated grass, tun and soil samples collected in May 1986 from the north eastern part of Poland. After drying and ashing, the plutonium was leached out by boiling with nitric acid, addition of NaNO» is necessary, serv ing for valency states to. be Uvi, NpV and PuIV /3/. Afterwards we carried o»' . the extraction with thenoyl-tri-fluor-acetone, 5 % in benzene -or with tric-actyl-phosphine-oxide 1 % in cyclohexene form IN HND,. R-~ extraction was performed either with BN HNO, or with cone. H2S03 . Finally samples were prepared for alpha measurement by electroplating, Si(Li)- or surface barrier detectors in connection with a multichannel spectrometer have been applied for alpha-measurement. Measuring times are between 70.000 and 150.000 s. Table shows a survey of different plutonium activity ratios dependence on fuel composition and irradiation conditions. 239+24U , ./23B Plutonium Activity Ratios, 0 D Sample Activity Ratio Reference soil 1.13 this work Clothes af workers worked in Chernobyl 1986 2.13 /5/ output In environment 1.15 - 2.4 /4/ fallout weapon test 35.7 16/ reactor water (25 % U enrichment) 0.6 /г/ fallout (NAK) 1.85 - 25 /4/ spent fuel: reactor operation time 1.4 a (2 % 235u enrichment) 1.72 П1 43t The ratio is more than one urdBr of magnitude higher in case of fallout measure ments due to atomic bomb tests than in spent fuel from a nuclear reactor. The reason for the higher ratio is lower irradiation time of the fuel, the higher portion of "Bu in the fuel and this ratio depends on energy spectrum of the neutrons, which is quite another in case of atomic bombs than in a nuclear reac tor. {Neutron crass sections are supposed to be equal for transuranium elements /8/.) Also in case of investigating reactor output originating of different types of spent fuel the ratio found out is quite another, as to be seen from the table. References /1/ G. Rosner, J, of Radioanal. Chem. £4 U981) 55 III U. Niese, S. Niese, 3. of Radioanal. and Mucl. Chem. 21 (1985) 17 /3/ F.I. Pavlozkaja, Т.Д. Gorjatsehenkova, S.M. Federova, W. w. F.ml janov, B.F. Myasoedov, Radiochimia 4_ (19B4) 460 /4/ J.M. Godoy, H. Schuettelkopf, M. Pimpl, KfK 3531 1983 /5/ L.A. Koenig, H. Schuettelkopf, S. Erat, H. Fessler, S. Hempelmann, K. Maurer, M. Pimpi, KfK 4115 (19B6) /6/ H. Schuettelkopf, KfK 3035 <1981) /7/ U. Niese, J. von Borany, P. Urwank, S. Niese, Isotopenpraxis 20 (1984) 401 /B/ O.c. Alkofer, J.M.H. Hauser, Atomkernenergie _13" C1968) 39 432 DETERMINATION OP ACTINIDES IN THE ENVIRONMENT 7-6 V.N.Kosyakov, N.G.Yaltovlev, M.M.Vlasov, P.E.Plskarev. Kurohatov Institute of Atomic Energy, Moscow, USSR A prompt and reliable tei&nlque for the successive determination of ura nium, plutonlim, amerioium and ourlum in a single sample baa been developed. Uranium ia determined photematrloaUy, Plutonium, sMrioium and ourlwa - radiometrioally «itn a liquid scintillation oountar (ISC) or a gas-flow co unter involving Blpha-epeotrometry. To separate the elenenta u»e la made of extraotion and extraction chromatography with trlcotyephosphlne oxide (TOPO). Pretreatment of a prepared sample includes usually the double treatment with 7Ж HBUj in KBrOj addition and heating, washing «1th 7И HSO3 and evapo ration of the joint solution to «at salts. The salt residue is dissolved in 1H HBO* and the prepared solution is divided into '.wo equal parts. One part ia used in datoroinise Plutonium, the second one goes for the determi nation of uranium, amerioium and surium. Aluminium nitrate and hydrogen peroxide are added to too solution for the determination of plutoniun to stabilize. Pu(rv), isolating It by extraotion with 0.05M TOPO in benzene at a volume aqueous-to-oreanlo phase ratio of 3:1. The extract ia «ashed with 711 HHO, and transferred into a vial with a liquid scintillators its alpha-activity ia determined with the LSC. When "T4i is used as a tracer, plutonium is reaxtraoted with 10% NH.HCO, and de termined from the alpha-spectrum. Plutonium can be reeztraeted also from the liquid scintillator in the same «ay. KBrO? is introduced into the solution for the determination of amerioium, curium and uranium to obtain 0.231 solution. This solution is passed through an extraotion-chronntography oolumn with TOPO on powdered polyethylene.. She filtrate forms the An and Cm fraction. Then the reduction elution of ceri um with 4K4fflO- is performed, after which uranium ia desorbed with 10* HH.HCO,. The Am and Cm fraction is evaporated and dissolved in 1M HLact+ + 0.07H DTP A + in Al(Hq3)3 [1] j Am and Cm are extracted with 0.2И TOPO in benaene. After «ashing the extractant its total alpha-activity is mea sured with the LSC. Another variant involves reextraction of Am and Cm with 711 H50, followed by talcing the alpha-spectrum or measuring the alpha-acti vity with the How counter. Uranium is determined photometrically by the method [2], therefore the eff luent uranium fraction ia evaporated to dryness and dissolved in 3.10_4H eraenasc III + 2.10-3H MPA • 5.10"2* HHOj. The process ohart of the technique is presented in Fig. The technique «as checked with the samples of aoil, "hot" partloles and aerosols from the region of the Chernobyl IFF. 28.3ак.1607 433 Sample Protraatnant 7HHHO, V2 1/2 C.Q$ H TOJO +/U(B03)3 4Дг03 I 7 и дю3 2 4 К ШЮ + 5* HgOg Extraction of Pu 3 4 H 1 д4ао3 + IO* ш ноо i«oounting of ^SWaste s 4 3 Pu in ISO iittiл toat дн^нсо, Column Bsextraotlon polyethylene iTOPO» of Pu from scin «lOtl tillator evaporationX , Wastes X-apeot- dissolution Evaporation rum of in 1И Blact Pu +0.07K DTPA +1H AlCff03), 0.2 H TOPO 2,3,4 zr Ж extraction of Ла, О Wastes Sataxminatlon of ol-oountlng 'Sal uranium with of Aa,Cffl, in irsanazo III bSC ТИШЮ, BaaxtranUon of Am.Cm fron aointillator Waetes J,- apeotrum of Am, Co The Proeesa Chart of Determination of Actinide Contents References 1. Koayakov V.H., Yarln E.A., Vitutnev Т.Н.// J.Radioanal. Cham. 1980. 2. Levakov B.I., Mlehenev V.B. at al-Zifeadiottiimiya. 1986. T.28, H 6. S. 795-79B. 434 THE ССИРЪЕХ ACTIHIDB5 COHCEHTRATIMG PROM THE SAMPLES OP I ?_7 ENVTRONHE1STAL OBJECTS I • I.A.Sobolov, R.G.bukjanova, A.Y*Panchenco, 0»V.Shurlcus, I.I-Masurina. Scientific Industrial Corporation "Radon", Moscow, USSR It. is known, that actinides ooour mainly in pseudo-colloidal state in na ture and sewage. In the contrast to the americium plutonium has the characte ristic pseudo-colloidal state which.can be maintained even in the conditions of acidation and prolonged keeping of sample. There are some methodв of con centrating actinides elaborated for extraction of simple ionic forme in radio chemical assays but they frequently can't be directly used for nature water and sewage, A method was suggested for the> actinides complex concentrating by means of extracting into the ironhydroxldemiomphat (HHI) based on combination of some methods, such as precipitation of actlnldes on iron hydroxide, liquid extraction by the monoieooсtylmethyIphoaphonic acid (MIOMPA) and following floatation of dispersed phase into the solid extract of Bffll. The optimal con ditions for complex concentrating were also worked out. The proposed method consists in acidation of sample to IB 2 and following addition of iron chloride in concentration 30 mg Fe3+ per 11 of sample under intensive mixing, then diluted solution of alkali is added under constant mixing till the formation of brown precipitate. After that the monolsoocthyl- methylphoaphonic acid and toluene ar* added under mixing for the formation of largegranulated precipitate of МВТ. Then the precipitate is separated by filtration, dried in the air and used either in radiometric measuring after preliminary soluting In chloroform and mixing with lumlnophor or in spectro- metric measuring with preliminary covering of polished plate with aliquot of eolation of the solid extract in chloroform with the following burning to at/ a and heating. The proposed method allows to determine the volumetric activity of plutonium-239, amerlcium-241f thorium-232, uranium-238 in range of 10"11-1(Г12С1/1. This method was shown to be successful in preparing of thin-layer epectrometric samples (100 mcg/cra ) obtained from the aliquot of solution of solid extract in chloroform* The method is universal because of it's ability to measure the total o(-aotivity of aotlnldee in sample both the using the radiometers on the base BDZA-201 or BDIA-detectore and ionizeting chamber and semi-conductor detectors* The optimal conditions for ^-spectrometry of samples were proposed in this work. 435 MAIN PRINCIPLES DETERMINING IBS BEHAVIOUR OP ТЕАЛЗОЕАНПШ ELEMEHT3 m KATURAI MRBAlIOSa 7~B v.D.Halukova, E.P.Kaymin, Institute of Physical Chemistry of the Academy of Sciences of the USSR, Moscow, USSR Transuranium elements may penetrate Into natural systems mainly ая a result of an accident or when using a formation as a depository of radioactive wastes. The present communication reports the data on the behaviour of americium-241, neptunium-237 and plutonlua-239 in alumo- silicate formations with water flows existing in them. Ihe main regularities of the interphase distribution of the above elements depending on their concentration, aeid-basio properties of the medium, the presence of the components modifying the form of existence of а radionuclide, including complex forming reagents and other parameters of the geological medium are considered. She possibility and condi tions of changing the interphase redistribution of the components due to a number of factors, e.g. themoradiatlon action, special chemical treatment of the medium, introduction in the pore apaoe or natural water of additional reagents have been analysed. The methods of calculating the migration of transuranium elements in water bearing horizons and the possibility of its limitation are considered. Xhe values of the main parameters characterising the sorption-migration dependence are reported for a number of different conditions of natural media. 43e COHCEHTRATIOB Of MICRO- AND KAMOOHAM MASSES Of ACT1HIDES , 7_ —I IN ABALYSIS OF SEWAGE ADD miROHMBKEAX. OBJECTS ! 1 V.I.Astafurov, N.l.Polkanova. Scientific Industrial Corporation "Radon", All-Union Research Institute of Inorganic materials, Moscow, USSR Analytical oontrol of actinide contents in sewage and environmental ob- iects often involves preoonoentration as the main operation. As a result of this operation the reliability and aocuracy of the analysis are Improved and measurements are simplified. The paper reviews the methods of concentrating micro- and nanogram masses of Th, U, ffp, Pu and Аш, compares the characteris- tics of these methods, gives examples of their employment in analytical prac tice. A nen technique is suggested for Plutonium concentrating by oo-precipi- tation; consideration is given to the regularities of actinide concentrating by extraction chromatography* Techniques are discussed for the destruction of colloidal and polymer forms of neptunium and plutonium and for the conver sion of these elements into a required chemical state, Piiitfm^im oo-preoipitation witty mawmneae ultrria*. for many years HnOp has been used for sorption recovery of elements from liquid samples» In particu lar, co-precipitation with ?'30« makes it possible to concentrate plutonium from sea water samples up to 400 1 in volume [1]. For the production of » 02 KHnO. is added to the sample and is reduced with NaKSQy The authors show that for oo-precipitation it is advisable to use previously prepared solut ions of Hn(IV) stabilized with zirconium. Their sedimentation stability de pends on the state of zirconium in its initial solution, ZrsUn ratio and aci dity; at speclfio values of the two latter parameters it can be high [г]. Methods of the classic extraction chromatography are advisable for concen trating elements if an analysed liquid sample is relatively small and this is due to both static and dynamic faotors. The paper analyzes the possibilities of the olassic extraction chromatography methods for concentrating Th, II, Np, Pu from acid solutions. Anting.» gnncentration using monolBOOotylmethylphosphonic acid (И10МРА). The method of plutonium concentration from aqueous solutions by sorption with a precipitate of ferrum (III) monoisooctylmethylphosphonate is widely used. The authors have studied the potentialities of MIOttPA base solex for concent rating actlnides. The coefficients of Th(IV), Pu(IV) and Am(III) distribution are compared for the cases of using H10MPA in liquid extraction versions, of sorption with ferrum (III) monoisoootylmethylphosphonate precipitate and of sorption with solex containing UIOUPA and its salt. References 1. Wong K.H., Brown G.S., Iloshkin Т.Е. // J. Radioanal.Chem. 1976.Vol.42.P.7. г. Inventor's certificate 1117285(USSR). The Procedure for Preparation of Nitric Acid Solution of Hn(IV). // Astafurov V.I., Vaohman A.A., Kolya- da N.S. - Bull. Iaooret. (USSR). 1984. N 37. P.67. 437 PRECONCEHTRATION, SEPARATION ЛОТ DETERMIHATIOH OF ACTISIDES Гт-То! IH NATURAL WATERS USIHG MEMBRAME FILTRATION L__J A.P.Novikov, T.I.Trofimov, V.M.Shkinev. Vernadsky Institute of ОеосЬотгпnti-y and Analytical Chemistry of the Academy of Sciences of the USSR, Moscow,USSR K.Geckeler, E.Bayer. Institute of Organic Chemistry, Tubingen, PRO The determination of trace aotinides In natural waters requires their pre- concentration «nd separation from interfering constituents. "liquid-Phase Po lymer-Based Retention" (LPR) is an effective method of elements preconoentra- tion and separation /"1/. These procedures are based on toe retention of ions Ъу a membrane which separates low molecular mass compounds from macromolecu- lar complexes of aotinides. The water-soluble polymers are commercially avai lable now. Рог the preooncentration of aotinides Doly(ethyleneimlne )oxine (POX) was specially synthesized in the Institute of Organic Chemistry, Unive rsity of Tuebigea.POX and poly (ethylene imine) (PEI) used on the retention studies had a molecular mass in the range of 30000 to 4000C g/mol. Earlier POX was used for the study of retention of actinides Л/. Ve investigated the possibility of preconoentration of trace concentration of aetinideo from natural waters and their separation by POX using LPR method. The results of the retention of 1KVI), Pu(IV), Hp(V), Am(V), Am(III), Cm(III) Of (III) by 2% POX at different pH valaes as a function of the filtration fac tor (Z), which is defined as the ratio of the volumes of filtrate and oell solution, are presented in Fig. It is worth to mention, that polymer-base poly (ethylene imine) does not form oomplexes with actinides in above mentioned «8 A 6 8 10 Z Retention of Actinides by a 2*5 Solution of РОл at Different pH Values ranges ft/. It is seen from the figures that all the elements сед Ъе concen trated during the filtration of neutral solution with the retention degree of 99%. The», Bp(Y) and AmCV) can be eluted by solutions with pH»«. 0-5.0 and tervalent transplutonlum elements In consequence Am ^ Cm > Cf are eluted at pH-3.0-4.0. So, In order to separate Am/Cm pair it 1в better to apply washing by oxi dant solution (aomonls perxenate) or to oxidize Am(III) to AB(V) alectroche- mically, Am(IV) and Am(YI) prove to be unstable In these conditions* It is convenient to oarry. out selective separation of fu from и by EDTA solution washing, uranium can be effectively removed by 1И nitric acid solu tion. Taking into account simple apparatus availability, rather high productivi ty and ecological purity of ultrafiltration method, it can be used for ooti- nadea isolation and concentrating from river water. Thus, LFR with POX cen be used for Pu isolation from river water, containing radioactive colloids, the loss of Pu at Z.20 not «needing 3-4%, References 1. Splvakov В.Уа., Geokeler K., Bayer E./ZBetur». 1985. Vol.315, H.6017. P.313. 2. Beyer В., Kberhardt B. et al.//Israel J. Ghem. 1985. Vol.26. P.40. 3. Hovikov A.p., Shkinev V.M. et aW/Radiochlmloa Acta, 1989. Vol.46. P.35. 439 ACHBTDBS П IBS ПАВ BBLB1SE OF IBB CHffiHOBYl ЮТ ACOXDHMI 7_\:\ A. S. Krivokhatakii, Yu. V. Dubaaov, 8. А. Salraova, >. T. Skovorodkin, 7, G. savonenkor, Kulopln Badlua Institute, Leningrad, USSB Beginning from the first dors after the aocid»nt, samples of soil contaminated with radioactive substances at distenoee up to~15 km from the CMPP ana aerosol samples in CUR premises and on the 4-th unit ware taken and radloohamleolly analysed. loohnogenlo partlelea of finely dispersed fuel and graphite «are (eparated from aoll aamplee by petrograpnie analysis methods; aerosol filters «ere processed by standard methods. Uranium, plutonlum, aaericlum and ourim «ere de termined in the samples. t*-Mtrta«s in. fuel nartlolea. •inaralogloally pure fuel partieles sampled at a distance" 0.5 km have else up to 1 am, the also deorea- alng «1th the dlatanoet down to~3 mom at 12 km. the particles' den sity la 8.3 в/о» • »o traces of melting are aean; on rare particles there is little oruet, probably of silioatea from the backfilling. *»o phases «are identified by x-ray radiography: UOg and i Ine fuel partlolea* spaclflo activity Tarlea ralatlra to **0e from 2>10* up to 1.2.10 Bq/g for purest fuel particles, being 7.7-109 Bo/g on the average. The iaotope composition of uranium in one of the samples lai 23*0 - 0.016 *, a350 - 1.17 *, 2360 - 0.16 *, 2J80 - 98.65 %. On April 26, 1986, the content of Plutonium in the fuel matrix was 7.6O0 Bq/g, of nnerlclum-241, 8.7-105 Bq/g. the Isotope composition of plntonium (by activity): *ru - 30 *, 239+ НОрц _ 70 «^ jass-Bpeotrometrie analysis of Pu In one of the partlolaa samples shoved: 238Pu - 0.25 *, 239Pu - 67.74 *, 2*°Pu - - 24.02 X, ^Pn - 6.21 #, MZSu - 1.73 S. №e Isotope composition of uranlvai and Plutonium corresponds on the average to a burnup 10.5 kg/t of V, №e contribution of ^Pn by alpha activity aomemhat variesi the ratio Z3BPu/239 + a+0Pn.0.3-0.6, being mainly 0.4. Soring first days after the aocideat the alpha aotirity of the fuel partiolos «aa determined mainly by a420n. «he 2«вв/2Эв+ 239 + 240^,, „ • lot 1 by alpha aotirity on the day of the accident. The ratio 233 +2lo pu/1l*oe« 6.10"4 In the time of the aoeldant. i-уНгчл.я in graphite. Individual graphite particles have else up to 1 mm in samples at a dlstanoe of "I km from the 4-th unit. B»e particles1 density is 1.7 g/co3, oraoknass of the graphite la seen with a microscope. stleklngs and lnelualona of fuel are seen «1th a mlaroceope on the surface of the partloles and in the cracks, aa «ell aa by alpha radiography, the fuel nay be removed from the graphite particles by means of strsng aoida. The content of **0e and alpha emitters In the graphite is determined by the content ef fuel «bleb reaches 5 < of mass In Individual partides . 440 Actinidae in aerosolB. Aerosol samples taken from air over the 4-th unit In 10-20 days after the accident also shoved 24SCm as the main alpha emitter. Besides, the aerosols were often enriched «1th uranium and plutoniun relative to **0e and 4 Co. She ratio U/Pu (mass) reached 1.5-10*, the ratio 239+ 2* 4, than Pu02 and U0gl during burning of graphite and soon afterwards. It may be connected with formation of chlorides due to the backfilling and plastics. Later the aerosols in the ground air layer were deter mined by wind lift of soil. The obtained data certificate that contamination of the soil and dust in the accident's area Is determined by long-lived alpb^-emitting isoto pes of Pu. The isotope * Cm has oractically decayed by 1989, but there is a fast accumulation of 4 Am and in the long-term outlook, also of 237Hp. STUDY ON THE ATMOSPHERIC ION COMPOSITION AT SOIL СОИТАМГНАДЮМ WITH THE DEBBIS FROM THE CHERNOBYL ACCIDENT 7-12 V.V.Smlrnov Scientific and Industrial Research Enterprise "Typhoon", USSR State Committee for Hydrometeorology, USSR The ion component state In the atmosphere of the Chernobyl Atomic Power Plant accidental area was experimentally studied for the period of 1986-1988. At the gamma-background level of several mllliroentgens per hour at 10 cm and 1500 cm above the contaminated soil surface the atmo spheric ion mobility spectrum forms (in the range of P^i.- 5 cm /V s ) do not significantly differ from the background spectra measured with the ваше spectrometrie devices over the European territory of the USSH, The increase of probability in occurrence of ions with intermediate mobility (0.05 ... 0*5 cm2/V-e ) is only noted. The ion mobility spectra inside the contaminated buildings are characterized by a wide variety of the forms. The content and altitude concentration profile ГЦ( ? ) of light ione ( /U-t= 0.5 ... 5 cm / V*s ) under these conditions markedly differ from the background ones for the ecologically uncontaminated regions* So, under weakly stable atmospheric stratification the profile fl±( 3 ) has its maximum at ^^Im independently of the ion polarity. The positive light ions are predominant near the ground and the negative ones at a height of 3 ... 5 m* At 2 > 10 ... 15 m the values of t%± and air electrical conductivity of A+ are close to the background ones 3 5 15 1 С ГЦ^Ю cm" , Л±-Ю" Я -^m" ) at the unipolarity coeffici ent of 0.8 ... I.I. The observed conductivity values characteristic of 2 > I m were 1 1 Я±= 600 4 200, Л_* 800 ± 150 Я" *"" . Heavy ion content < f&± ъ. 0,03 cm /V'S ) at points of measurements in the Chernobyl Atomic Fewer Plant area docs not markedly differ from the background one. The dis turbed atmospheric models and the possible ecological after-effect are discussed. 441 EXPRESS DETECTION OP PLUTONIUM I» ENVTHOHMEHTAli OBJECTS 7.13 I.K.Shvetaov, B.S.Kaliniohenko, V.G.Kulazhko, V.A.Kalistratov, N.A.Kslaahnikov, S.V.Pirozbiov, Y.A.lchelin, V.M.Shubko, Yu.P.Rodlonov. Kurchatov Institute of Atomic Energy, Moscow, USSB An express teohnique has been developed and Buooeasfully checked for the purpose of operative control and determination of the plutonium concentration in the vloinity of the Chernobyl №?• The technique la baaed on the incomple te dissolution of samples followed by extraction of the plutonium isotopes with the solution of tri-n-ootylamine (TOA) in O-xylene. This technique has the advantage reducing considerably the time of analy* sia over other methods that involve the oomplete dissolution of samples analy zed. The use of plutonium-236 аь a tracer makes it possible to control the chemical yield of the process. The basic stages of determining the plutonium oontent of soil are the fol lowing Sampling and preparation of samples * Leaohing of radionuclides 7И ШГО, • 0.2M KBrO, 3 i - Extraction of plutonium 1056 IDA I Preparation of *C -source f The degree of leaohing determined X -spectrometrically from the amounts of cerium-141 in a sample prior to and after leaching is not lees than 9056 The chemical yield amounts to 80-6596. The total time of the chemical analysis from the beginning of leaohing to radiometrio measurements does not exceed three hours. 442 FORMS OP OCCURRENCE OP PLUTONIUM XH SOILS 7-14. r.A.Goryachenkova, P.I.Pavlotskaya. Vernadsky Institute of Geochemistry and Analytical Chemistry of the Academy of Soiencea of the USSR, Moscow, USSR It is essential to know the forma of occurrence of plutonium in soils determining the intensity and trend of migration for the reliable control of the environmental pollution and prognosis of plutonium behaviour in the overground ecosystems. The investigation was carried out in model laboratory and field experi ments on typical soils of the forest and the forest-steppe zones as well as on various types of soil contaminations resulting from the reactor accident at Chernobyl. It was established that in soils the content of plu tonium in water-soluble, exchange and lightly soluble, mobile, acid-soluble and amorphous forms depended on the type of pollution and increased in the range: the fine-dispersed fuel of unaffected compositionс the fuel enriched by volatile products of ejection< fugitive compounds of plutonium (Table 1). The content of water-soluble plutonium in soils was not great (^1%) and only in carbonate soil it reached 3%. The influence of the type of soils on plutonium content in the lightly soluble and mobile forms attached to contamination of soils soluble compo unds of Plutonium were shown. It decreased while the content of humus and heavy fractions of mechanical composition increased. For instance, the quo ta of lightly soluble plutonium was estimated to be 14, 3 and 2% in soddy podzolic, forest grey soils and leached chernoaeni[ for the mobile plutonium -5, d and 1 per cent. The content of plutonium in the amorphous form (in compounds of chemical elements with natural organic substances and alumini um-iron hydroxides) was independent of the type of soil and sources of its occurrence in the environment (82-86;,?). The influence of the time and con ditions of plutonium occurrence in soils on distribution of this element between water-salable, lightly soluble» mobile end amorphous forms was not found- This fact showed a very quick accumulation of plutonium in soils. The careful investigation of plutonium distribution between the compo nents of inorganic and organic parts of the soils was considered* The main quantity of plutonium in soils was found to exist in the compounds of cal cium, iron and aluminium with humus and low-molecular acids and in hydroxi des of the two latter elements. Plutonium distribution between these groups of compounds was determined primarily by the physico-chemical properties of soils. The low Plutonium content in mineral fraction of soil species ( -£Л%) indicated that plutonium slowly penetrated into the crystal lattice of soil minerals. The data showed that plutonium is tied with all groups of organic compo unds in various types of soils. Plutonium content was found to be 16-71% in humic acids and their compounds with chemical elements; and 6-12% - in fulvic acids. In the group of humic acids the main quantity of plutonium was found in the composition of calcium humats (72-87%); 4-18% - in humic acids bound with relatively stable iron and alumlni.ni hydroxides, and 4-16% - in the composition of humic acids with mobile hydroxides. In the group of 443 fulvlc acids of soddy-podzolic soil*»5Q& of plutonlum was found In the free acids and their compounds with mobile hydroxides, while In leached chernozem it wee only 0.3#> The obtained data permitted to make a conclusion that plutoniuro occurrences exist in soils in various compounds differing in their solubility. This fact explained the observed conformant a of Its distribution and migration in soils. The elevated plutonium quantity was found in relatively soluble forms after the accident on ChAS. It permitted to conclude that the plutonium behaviour would be determined by the same law and mechanisms of migration as those previously established in case of other sources of plutonium occurrence in soils* Table*.Existence of Binding Pom of Plutonium in Sella, * Conditions and type Water-soluble Mobile Acid-soluble Amorphous ' of pollution ShASS, fine-fralned 0.1-0.3 0.4-1.4 4 10-21 luel invariable compo- litioo (type A) tael» enriching 0.8 2.1 15 60 >y fugitive products [type B) fugitive nroducte 2.7Z> II2» 55-88 692)-86 [type 0,D) lodel laboratory 0.1-0.2 1.6-4.5 81-99 85-88 txperimenta ixperimental plot 0.2 0.7 91 S2 Notes.1) Soluble in T зшш'в solution, 2) The soil «it i high carbonat s oontent. Table 2. Plutonium Distribution between Organic and Inorganic Components of Soils, % ioddy podzolic Potest grey Leached chernozem Compounds 1> 1) У 2> Free humus acids 31.0+1.1 35.6+1.2 54.3+1.6 47.0+1.3 and their compound »itb Ca.Fe.Al and other Hydroxide Fe and Al 66.6+1.9 59.4±1.3 43.4+1.9 50.0+1.1 Organic aubetances 1.4+0.2 1.5+0.2 0.8+0.07 1.2+0.5 released from bond •ith R203 Organic substances 0.5+0.08 1.6+0.2 0.5+0.05 1.2+0.5 connected with clay partioles illneral fraction 0.5+0.03 1.0+0.05 1.0+0.002 0.5+0.4 Notes.1) Laborat ory contamlnai ed soil» 2) Bxperim ental plot sol 1. THE CHERHQKfL РИЖШШ1 MIGRATION IN SOILS 7_,5 F.I.Pavlotskaya, I. B. Kazlnskaya, E.tt.Korobova, B-F.Myasoedov, V.V. Emelyanov. Vernadsky Institute of Geochemistry and Analytical Chemistry of the USSR Academy of Sciences, Moscow, USSR Radiation situation forecast needs the information not only about radio nuclides concentration but also about the plutonlum behaviour peculiarities in soil} the latter containing 82-99.98 of the whole eoosystem plutonlum pQ and being the food chain primary link. In 1987 a number of various geocheml- cally linked elementary landscapes were studied in order to investigate the Plutonium distribution in soils; the samples being tak-;n in 2-5 cm layers from the earth's surfacr up to the 20 om depth with due regard for the gene tic horizons. In 1986 the soil samples were taken with the help of a standar dized metal ring (H-14 cm, h*5 cm) and later devlded into the layers 0.5* 1.0 cm thick. The Plutonium content was determined radiochemical^ after the sample HF and НПО, treatment and 3 Pu tracer applying. The plutonlum concentrating and radiochemical purification were carried out with the help of the complex- forming sorbent polyarsenazo-n followed by the further cleaning at the small VP-UP anlonlt column. The isolated plutonium was detected at the ionization chamber. The detection limit was ~1.7»10~^ Bq. The natural factors influence upon the earth's surface plutonium distribut ion has proved to become apparent a year after the Chernobyl accident. The minimum plutonium content was found in the wet valley bottom alluvial soil, the maximum one - in the terraoe dry soil; the attaohed to the terrace low land sail obtaining the intermediate plutonium concentration. The element quantaty in the pine-forest soil appeared to be lower, the main plutonlum concentration part being found in the upper one-centimeter moss laysr (92%?. In all the investigated landscapes the 73-94$ of the plutonium were accu mulated in the upper 0-2 (3) cm soil layer, nevertheless the element vertical distribution varied and depended upon the soil type, genetic horizon and plantB cover type, in accordance with previous results Zg7. For example,less humle sandy soil differed from the more humic valley bottom soil, covered by the cereals near tbe roots bushing knots, by plutonlum more even vertical distribution. The carbonate soils appeared to show the most intensive pluto nium migration. The slow and fast soil plutonlum migration types were revealed; the for mer being ~ 90%, the migration ooefiolents coinsiding with those found before /27. The results prove the Chernobyl plutonlum has already bee» included in the blogeochemlcal cyclic migration and the element's behaviour in soils being the same as that of the plutonlum coming to the environment from the other eouroes. References 1, Pavlotskaya F.I., Follcarpov G.B. // Itogy nauky i tekhnlky. Radiatsyon- nay biologya. T. 4. Radioecology Problem's. Moscow: BIHITI, 1983. F. 99. 2. Favlotskaya F.I., Ooryaeheokova T.A., myasoedov B.F. // Atomnaya energla. 1986. Vol. 61. P. 195. 44S DETERMINATION OF THORIUM, URANIUM, PLUTOfllUM AKD AMERICIUM IN ENVIRONMENTAL OBJECTS, MAN'S BODY AMD BIOLOGICAL MATERIALS I " V.I.Astafurov, V.I.Bad'in, N.N.Kononykina, V.S.Gromov, I.D.Bulanova, V.V.Mordashova, I.D.Zabolotskaya, V.N.tfrolova. A13-Union Research Institute of Inorganic Materials, Biophysics Institute of the Ministry of Health, Moscow» USSR The intensive developments of nuclear power and an ever increasing use of radioactive species in cosmic engineering and scientific research require a reliable control of an environmental actinide content and actinide entry into bodies of men and animals. The paper considers the methods for the determi nation of Th, U, Pu, Am in invironmental objects, man's body and biological atmospheres, compares the characteristics of these methods and gives recom mendations as to how to use them in analytical practice. When determining plutonium analysts are faced with some difficulties due to diversified substances under study, their complex composition, low Pluto nium concentrations in a great number of objects being controlled and an ever increasing content of alpha-emitting nuclides of other elements* A high er Duraup of nuclear fuel, recycle of regenerated uranium and tranaplutonium element production lead to an increased entry of high, activity nuclides of Th, IT, Am, Cm into the environment. Their presence in objects being analyzed makes practically impossible a direct radiometric determination of plutonium and requires its isolation from alpha-emitting nuclides of other elements. The paper present high selectivity methods of plutonium determination in ef fluents and natural water, urea and uranium aerosols sorted on filters from air under control. A change in the radiochemical composition of impurities controlled leads to the fact that due to insufficient selectivity the majority of the methods presently employed for the determination of nano- and picogram masses of actinidea can be only recommended for the analysis of a limited number of ma terials. In this connection it is highly urgent to develop selective methods for determination of individual radionuclides! these methods must be suffi ciently rapid and simple so that they could be employed for routine analyses. The authors suggest some methods of thorium, uranium, americium determinat ion that have в high selectivity as compared to the ones employed. They com bine sorption concentration,liquid extraction and extraction chromatography in its classical version and in the version using solexes with radiometry, alpha- and gamma-ape с trome try, laser fluorometry and spectrophotometry. Con sideration is given to complex determination of actinidea using one sample of a material analysed and their direct determination with physico-chemical and nuclear physics methods of detection, in particular, employing whole body counters. Some peculiarities of a sample preparation are discussed in the radiochemical analysis of biosubstrates containing substances introduced into a body to accelerate radionuclide withdrawal. 446 DISTRIBUTION OF 237Np, Pu ISOTOPES AND 241Ara IN LAKE AND SEA SEDIMENTS 7-17 Masayoshi YAMAMOTO, Kazuhide CHATANI, Yoshiyashu YAMAUCHI, Kazuhisa KOMURA, Kaoru UENO and Masanobu SAKANOUE Low Level Radioactivity Laboratory, Kanazawa University Tatsunokuchi, Ishikawa 923-12, Japan With the importance of nuclear waste disposal problem, it becomes more and more indispensable to know deeply the behavior of transuranium elements in the environment. Among the transuranium elements, field investigations 237 6 on Np (half-life : 2.14x10 у, о) are very sparse as compared with those 241 on Pu isotopes and Am. 237 To understand the sedimentary behavior of these elements, Np in sediment cores collected from the Mikata Five Lakes (35°34'N,135°53'E) along the Japan Sea coast has been measured together with Pu isotopes and 241 Am. The Mikata Five Lakes have different characteristics in the narrow area : sea water (Lake Hiruga), brackish water (Lakes Kugushi, Suga and Suigetsu) and fresh water (Lake Mikata) (Fig. 1). Therefore, it is very interesting to study the sedimentary behavior of these elements from a viewpoint of effects of the environmental conditions. For the determination of these nuclides, the sequential separation of Np, Pu and Am was carried out, 239Np. 24ZPu (236Pu) and 243Am being used as yield tracer for each element. The alpha-ray activity of each electroplated source was measured by using an alpha-ray spectrometer with a Si(Au) surface barrier detector. The determination of Pu was also carried out by using a low background liquid scintillation counter. The activity ratio of 237Np/239,240Pu calculated from the total inventory in each sediment core is 0.1 - 0.2S! for Lakes Hiruga, Suigetsu, Kugushi and Suga, and about 0.3Ж for Lake Mikata, respectively. These values are lower than the values of 0.3 - 0.4? for the soils of 0 - 20 cm depth, except for Lake Mikata. A careful comparison of the distribution pattern of these actinides and their activity ratios will be presented together with data for the estuary or sea sediments along the Irish Sea. m was» тог С л WAKASABAV SM Fteirie p Ом» Lake A В С W V BJWSH1-.? L.HIRUGA 0.95 14.3 3S.5 L.KUGUSHI 1.4S 0.8 г.5 *|4 s ч L.SUIGETSU 5.02 14.3 34.0 ^ $ч "• "^ ^ w. ' L.SUGA 1.00 4.6 13.0 LAKE .• ^Х*-"-*¥ • SUM L.MIKATA 3.61 1.3 5.8 V „U1E4, A: Area (km) ^JQ HIKATA B: Mean depth (m) i К C: Max. depth (m) Fig.l Sampling locations of sediment cores in the Mikata Five Lakes and feature of these lakes. wa im IBM m» mi Oopth of Hdlfflent core ( cm l Depth of atament eoro ( en ) 237 239 240 241 137 Fig.2 Depth profiles of Np, ' pu, Am and Cs In sediment cores from Lakes Hiruga and Suga. QUICK DETERMINATION OP ALPHA-EmlTTINS NUCLIDE CONTENTS IN £m»UJ£NTS|l; 1 AND NATURE WATER USING ULTRAFILTRATION AND LARGE-AHKA SILICAN DETECTOR BiSE ALPHA-SPECTROMETRY V.A.Kichik, M.I.Kraplvin, N.P.Kuleehov, M.N.Maelova, V.G.Xudina. All-Union Research Institute of Inorganic Materials, Moscow, USSR Radiometric determination of alpha-emitting nuclide contents of natural water and low specific activity solutions maizes it necessary to concentrate considerable volumes of solutions to be analysed by evaporation and copreci- pitation. This» in its turn, results in a dry residue layer formation from alpha-specimen preparation making measurements difficult* To obviate labour-oonauming long-term operations of needless salt dis charge during thin dry specimen preparations for alpha-spectrometrie deter mination of alpha-emitting nuclide contents an analytical method has been worked out using ultrafiltration. Ultrafiltration used in combination with the selective binding of ions analyzed with soluble high molecular reagents made it possible to significantly simplify the analytical procedure* To a solution being analysed a selective water soluble polymer is added that binds actinides into macromolecular complexes. Water soluble polymers con taining inline and phoaphon groups of polyakrylphoaphonic acid and polyethy lene imlne types can be binding agents practically for all alpha-emitting nuclides. Using an ultrafiltration cell having a separation polysulphonamide dia phragm, alpha-emitting actinide elements are separated from the main salt mass of a solution. She diaphragm coated with an alpha-emitting nuclide con taining helium layer is dried a little and used for alpha-apectrometric mea surements t The amount of the dry matter on the diaphragm - target is hund reds of times less than that when the standard method is used and this con siderably improves the efficiency and resolution ability of alpha-spectro- metric measurements. Por measurements the use was made of an alpha-spectrometer based on a si- 2 llcon detector having the sensitive surface area of 20 cm and the energy resolution of 50-70 kev for Б *5*5 UeV. The lower limit of alpha-emitting nuclide detection in a solution was 0.1 Bq/1. The overall duration of the analysis using ultrafiltration and alpha-spectrometry was about 1 hour instead of 3.5 hours required by the standard method. The worked out method can be used as a standard one in the process cont rol of purification works employed by radiochemical industries and^research centres as 2440m, Z41Am nuclides. 2Э.ЗЛК.1607 ME USE OF ULTRA LOW-LEVEL LIQUID SCINTILLATION COUHTIBG IN | 7_,9 THE BETERIIINAIION OF ACTINIDES IN THE НПП»ОЮ1ШТ I . F.Schonhofer, Federal Institute for Food Control and Research, Radioehemistry, Kinderspitalgasae 15» A-1090 Vienna, Austria Liquid aaihtillatlon oountlng has teen applied «1th great success during the last years for measurement of several beta and alpha emitters. Liquid scintillation counting provides the big advantage of high efficiency . In the case of alpha emitters it is approximately 100%. Sample preparation is easier than in most other techniques, very often extraction methods are- employed which yield sample solutions which can he mixed directly «1th scintillators and counted. A drawback is the rather bat resolution compared with surface barrier detectors - full width half maximum is typically between £50 and 350 keV. The literature on determination of aetinidea by liquid scintillation counting at environmental. levels will be reviewed. The use of alpha-beta dis crimination will be dieoussed and data on the lower limits of detection which can be achieved will be presented. DETERMINATION OF LOW-LEVEL „d-EMITTERS Kt EXTRACTIVE II SCINTILLATION ' " I D.C.Lauria, Institute de Radioprotecao e Dosimetria, Rio de Janeiro/Srasil D.Xengi Institute of Nuclear Energy Technology, Tainghua University, Beljlng/P.R.Chlna S.Hobiue, C.Keller, School and Nuclear Teohnology, Nuclear Research Center, Karlsruhe/FRG A simple and rapid method la described which allows the enriohment and se lective determination of ^-emitting actinlde elements in environmental samp les, e.g. In filter dust. It Is based on the selective extraction of the in dividual element directly into a specifically selected scintillation coctail which also contains the completing extractant, e.g. tri-n-ootylphoaphine oxide (TOPO). To determine uranium and transuranium elements, the following procedure is used after dissolution of the sample: - extraction of U and Pu by 0,1 M TOPO/toluene from 4 И HNO,, - reextraction of Pu into 0,5 M ascorbic acid/1 м НС1, - extraction of Am/Cm by 0,3 И ВДРО/tolueue from the adjusted aqueous solution (pH ш 1) of u+Pu-extractlon. The advantages of this fast method are good extraction yields combined with high oountlng efficiency, even in the presence of larger quantities of P~ and ^-emitters. A detailed description of this analytical method le given together with same applications. Comparison of this method with the use of Gridded Ioni- sation Chamber for direct oounting is also provided. Presently, investigations are underway to extend this procedure also to include neptunium as well as other ^-emitting elements ooourrlng in envi ronmental samples, like thorium, radium and polonium. 450 ЛОТНПЭЗ 3IFPUSI0H IB GLASSES IHCOHPOIUTIHG MODEL RADIOACTIVE i 1 TM5TES 1 Ss2O-26,0; Al20,-24,6i Рг05~49,4. Glass 2: Na20-26,0; UOg-0,3; Zr02-1,4» Cr20j-1,8s Ho0j-1,1;Pe2O3-3,6f HiO-1,1; Al203-15,3; P205-49,4. Glass 3: Наг0-16,1; CaO-17,5( Al20,-16,6; B20?-20,0s SiOg-29,8. Glass 4: Mag0-l6,l! Cs20-2,1; MgO-0,9; Ca0-1,0j SrO-1,6; La203-9,O; Zr02-0,5} Fe20,-2,4s AlgO,- -16,6j B203-20,0( SiOg-29,8. Actinides теге found to be the least lees mobile radionuclides. In parti cular, diffusion coefficients of neptunium, plutonium and amerioium in alu minophosphate glasses at 673 К are similar and equal (1-2) 10" m s . In aluminoborosilicate glasses their diffusions! mobility at 773 К is still less and equals about 10 " m s . Actinide diffusion coefficients in the glasses investigated are 10-100 less than those of caesium and strontium. This evidently results from stron ger electrostatic interaction of actinide element cations with the nearest anionic surrounding as the values of actinide cations ionic potentials are higher than those of caesium and strontium cations. Glass devitrification is shown to increase the diffusions! mobility of radionuclides due to the formation of simpler migration paths through inter phase boundaries, micro- and macrocracks. This proves once more the necessi ty of vitrified radioactive waste storage at temperatures preventing the possibility of material crystallization. The influence of adsorbed moisture on low temperature neptunium migration in crystallized aluminophosphate glass 1 is revealed. References 1. Hatzke Hj.//Themodynamies of Nuclear HateriaLb 1979. Viemla:IAEA, 19S0. Vol.1. P.311. 2. Inoue T. et al.//J. Nucl. Sci. and Technol. 19B6. Vol.23. P.56. 3. Dunn T.113. Яоп-Cryst. Solids. 1987. Vol.92. P. 1. 4. Ivanov I. A. et al.//Heptuniura and Plutonium Chemistry. Theses of the 3 All-Union Conf. Septs, (Leningrad, Nov., 14-26, 1987}. L.: №uka. 19B7. P. 9 J. 451 METHODS TO STUDY HUMAN HAIR RADIOACTIVITY I - 22 L.I.Zhuk, A.D.Belyayev, A.A.Klst, T.P.Pikul, K.I.Hadyuk.Institute of" Nuclear Physics, UzSSR Academy of Sciences, Tashkent, USSR Human heir appear to b« s substrate providing the information about the external and internal environment. Besides, hair speciemn are easy to obtain. The conservative nature of the hair elemental composition la considered to be an important advantage for studies. Here, a 12 cm hair sample provides a year-long accumulated Information. In order to lnterprete the data obtained, the average hair growth rate was taken equal to 10.5-1? mm per month, although it may differ from individual to individual. Samples for removal of surface contaminants were prepared by the method recommended by IAEA. This includes double washing by acetone and by deionized water followed by drying in the air» The samples were weighed, placed In clean plastic bags, marked and analysed. Neutron-activation techniques to identify 24 elements. Including uranium, have been developed at the Institute of Nuclear Physios, Academy of Sciences of the UzSSR. Uranium was identified by neptuniuni~?39 following 15 hours of hair sample irradiation by a neutron flux of 5*10 ~Wcm sec. Induced radia tion was measured 5 days after the procedure.Irradiation was done on a Ce-I detector. The detection limit was 0*01 Ag/g. Cesium radionuclides are known to accumulate la human hair during the whole period of hair growth as a result of metabolism. The eeslum-137 speci fic activity in hair quickly achieves the dynamic equilibrium state in re ference to the specific activity in a human body. long life of hair, hard keratin structures in a hair trunk allow the preservation of most of the radionuclides for a longer period of time compared" to other tissues. A method to detect the specific hair /3-activity using a low-background device has been proposed.Isotopic composition was determined by genua-spe ctrometry using a semiconductor germanium-lithium detector. Radionuclide composition is quite diverse and may be used to estimate the levels and distribution zones in the environment. In order to detect eC -active radionuclides In hair a solid-state track technique using LR -445 track detector has been applied. Exposure time was 10-?5 days depending on the p£-activity value of the sample stu died. The overall hair эС-activity was measured in a vacuum chamber by a semiconductor detector. ^--Activity determined by these two methods has given satisfactory coincidence of values for the same samples. More information is provided by the distribution of elements, /b- and cL -emitters along the hair* It reflects, with some delay In time, the changes of their level of content In the environment as well as in the orgamiem. The Investigations carried out allow one to draw a conclusion about the possibility to use the information on the radionuclide and elemental hair composition in order to evaluate unfavourable impact of the environ ment on a human organism. 452 AUSHOBS ШВВХ Aalto Т. 40 Babulevieh H.E. 414 Aaltonen J. 40 Bagreev V.V. 324, 388, 339 АваишшМ Н.И. 155 Babaln V.A. 311 Abney E.O. 239. 356 Bad'in V.I. 446 Abraham Н.Ы. 84 ВаЮует S.A. 407 ADumida M.A. 398, 404 Ball D. 84 Afonin M.A. 254, 256, 300, 342 Balteneperger U. 235 Ahmed P.M. 181 Balukova Т.О. 436 Aleanbare Ж.Х. 197 Baran A. 144 Akella J. 111 Baraniak L. 249 Alezanarav B.M. 43 Baranov A.A. 126, 375 Allkhanyan A.S. 200 Barbanel'lfu.A. 89, 142 Anmerger Ы.-В. 75 Barsukova K.V. 348 Aaorettl G. 97 Batenkov 0.1.43 Anan'eva I.ll. 397 Batil V.G. 53 Ananthaelvan K. 164 Bayer В. 43В Ananyev A.V. 155, 181, 347 Baaela W. -149 Beauvy H. 107, 146 Andersen R.A. 203 Begun G.H. 93, 225 Andreev A.N. 48, 50, 130 Bebrens R.9. 166 Andreev A.V. 156 Belyayev A.D. 452 Andrew J.?, 212 Belyaev v.D. 418 Anireyohuk H.N. 373 Benedict U. 79, 167 Andrianov H.A. 213 Berg O.J. 203 Abo K. 40 Bergman J. 40 Antbonyaamy S. 164 Bettonville S. 201 Antropov V.P. 69, 70 Beyralehov A.G. 184, 193 Aral У, 162 Bevz A.S. 172 Artpov G.A. 407 Bhattaebaryya S.H. 258 Arlta Y. 113 Blsmondo A. 118 Artemova L.A. 382 Blaise A. 97 Aehavakeya B.O. 250 Bliaov A.B. 43 Aaprey L.B. 239 Blinov H.V. 43 АегаЛп-ov T.I. 393,418,419,437,446 Boatner Ь.А. Э4 Auurman L.H. 86 Avens L.B. 239, 356 453 Bodrin G.V, 3u8 Cooper B.H. 8i! Bogdanov D.D. 48, 50 Crawford H.J. 429 Bolotin M.G. 326 BomMeri G. 132 Daboa-Selgnon S. 79, 167 Boncella J.M. 203 Daaesi P.R, 263 Borin b.L. 128 Dash K.C. 341 Borkowskl H. 67, 249, 431 David P. 365 BoUcher P. 171 Davydov A.V. 197 Bxaun T. 389 Bedaonkar V,G. 277 Braverman I.B» 22 Dal Ool Q.D. 93 Brooks U.S. 12 Deulln G.I. 287 Brucnertaelfer H. 44, 47, 57, 233 Bevina O.A.120 Briichle W. 235 Dittrioh S. 263 Budantseva И.А. П9 Lmitriev V.D. 53 Bukina I.I, 345 D'Olieelager W. 170 Buklanov G.V.47,57,231,263,274,275 Domanov V.P, 227, 233 Bulaaova I.D. 446 O'Donnel T.A. 356 BuilitB E. 261 Dreyer Я. 263, 274, 275 Burtcev I.A. 317, 344 Dronova l.V. 342 Broznik Г.Р. 215, 219 Dubaeov Yu.v, 440 Caciuffo R, 97 Bubrova l.V. 368 Campbell G.M.213 Buabln R,B, 89 Capdevila H. 357 Dvorak Z. 319 Carnall W.l. 60, too Byatlova H.M. 330 Caearei H. 27 Caaallato U. 191 Cbakravortty V. 331, 341 Eccles H. 15 Charbonnel Ы.С. 313 Edelatein M.M. 75, 84, Chatani K. 447 Chaudfcuri U.K. 247 Bfimov И.В. 120 Chebotarev N.T. 213 Egunov V.P. 223 Caekmarev A,H. 326 Elchler B. 140 Chepahugova T.Yu. 420 ElbenovakyU. 104 Chepigln v.I, 48,50 Eller P.G. 239, 356 Cherezov S.K. 85 £1 Waer З.И. 347 Chlbissv Л.К. 396 Emelyanov V.V. 445 CMetyakov V.H. 126, 375 Eriksson 0. 12 Cluim-tova И.К. 308, 310, 311 Erin E.A, 126, 375 Choppin G.R. 426 Bryomin A.V. 48, 50 Chubukova Т.Н. 402 Evseeva T.I. 420 Qhuburkov Yu.T. 54, 227 Chndnovskaya G.P. 89 Chumaevakl N.A. 188 Ooddtna 0, 74 Paraglia G. 189 Fedorov G.B. 147 CondamlAee Я. 313 Fedorov V.S. 413 Conotantineecu 0. 47, 57 Fedorov iu.S. 294 Fedoseev A.M. 179, 241, 383 Soodman G.L.60, 100 Fedoseev D.A. 382 Gorbunov V.B. 120 Fedoeeev B.V. 197 Gorbunov V.P. 99 Fernando G.W. 82 Gorpenko V.A. 396 Figiel H. 144 Gorshkor I.Yu. 53 Filatov I.Yu. 200 Goreki B. 45, 47, 23*1, 422 И.Ш V.S1. 99 Goryachenkova T.A. 427, 443 Filippov E.A. 22, 31, 337 Gourier D. 203 lilippov V.I. 416 Grebenehohlkov H.P. 198 Finch C.B. 84 Gregorioh K.E. 235 Fliteiyan E.S. 407, 424 Grigoryev M.S. 208 Foamier J.B. ?'i Gromov B.F. 419 Fregona S. 189 Gromov V.S, 446 Frenkel V.Ya. 350 Groeei G. 27 Prldkin A.M. 53 Gromova E.A. 53 Frolov A.A. 373 Gubanov V.A. 69, 70, 76 Prolov K.H. 353 Subina M.Yu. 382 Frolova L.H. 373 Guerriro B. 189, 191 • 2&Ч Frolova, V.H. 393, 446 Guillaunont H. 230 Fuger J. 11 Gulin A.M. 451 Gureev E.S. 52 Fujino I. 114 Gurevieh V.M. 120 Puks L. 67 Gnseva b.I. 233, 279, 281 Fukushima S. 162 G'aggeler H. 235 Halre R.G. 17, 93, 215, 225 Gajek Z. 77 Ball H.L. 235 Galkin B.Ya. 243 Bands H. 162 Gangrokii S».P. 85 Bovelal. 130 Ganguly B. 258 Beerman L. 170 Gannett CM. 235 Heloig W. 431 Gasparini G.M. 27 Henderson R.A. 235 Gavrionev K.S. 120 Herrmann •>• 11 Gavxilov K.A. 227 Hlldebrand D.b. 211 Gavrish Yu.I. 89 Hill R. 426 Gavel W. 1«8 Binstsu Y.186 Gazlav 3.A. 236 Hlrai S. 410 Geckeler K. 438 Bernard L. 167 Hlrayama H. 206 Cibsoa J.X. 17 Hobart D.B. 225 Gilewski A. 158 Hoffman D.C.235 Glebov V.A. 87 Hoffman F. 421 Gleiaberg B. 233, 408, 422 Horiki M. 160 Gliva V.B. 394 Hubert H. 313 Gotfart J. 201 Huseonnoie H. 47, 57, 233 Gogolev A,V. 383 Hutchinga И. 97 Golovnya V.Ya. 53 Ichinooe N. 186 Golynko Z.8. 315 n-yahenkov V.A. 205 Goncharov V.Ya. 416 Inroto 8. 64 Ionov V.I. 34 Khatamov Sh. 407 lonova G.V. 65. 71, 83 Khlebnikov S.V. 53, 85 laoslmov I.N. 85, KhoaatovflHy I.L. 106, 120, 121 ttt4 J.P. 167 Xhujaev S. 52 Ivanov I.A. 451 Kichik T.A. 449 Ivaoov I.P. 121 Kim K.C, 81 Ivanov H.P. 57 Kim U Zin 227 Ivanov V.V. 221 King Ы.А. 166 Ivanova L.A. 308 Kinkeaa S.A, 239, 356 Ivanova S.A. 340, 394. 395 Kirihara I. 160 Iyer V.S. 116 Stat A.A, 361, 407, 452 Izmalkov А.Я, 223 Kleinachmidt p.D. 211 Jedlnakova' V. 319 Klyguln A. I. 33 Johansson B, 12 KOber V.I. 122 Jost D. 235 Kochergin S.ls. 209 Koklna S.A. 301 Jove J. 65 Kolin V.V. 89, 142 Juravlev K.G. 185 Koltunov V.S. 353, ->70 Kabachenko A.P. 48, SO Kolyada M.S. 33 Kabaob&lk H.I. 308 Kama X. 410 Kaczoroirekt D. 153 Komarov E.V. 108, 254, 25S Kalaabnikov H.A. 41, 385, 442 Komura K. 447 Kalevicb E.s. 223 Koaonykina N.N. 44S Kaliappan I. 164 Konovalov l.II. Kallslchenko B.S. 41, 385, 442 Konyaev А.Б. 412, 413 Kalietratov V.A. 330, 442 Kopylov B.A. 256 Kamenskaya, A.N. 135,238,252,260 Kopyrln A.A. 269, 300, 317 Kapranohik V.P. 269 Kcpytov V.V. 375 Kapehukov I.I. 172 Korobova E.M. 445 Karalova Z.K. 345 Korolev V.V. 256, 300, 342, 344 Kexbovnichy p.l). 375 Korotkov I.A. 392 Kardivarenko L.M. 339 Korpusov O.V.29 Karelin A.I, 31, 210, 403, 418 Kosltayn V,P. 412, 413 Karpyuk A.D. 33 Koayakov V.B. 2333, 361,363,399,433 Kartesheva N.A.305 Ket W. 84 Kaeimov P.O. 37f Kotlin v.P. 89, 142 Kattalnen a. 40 Kovalenko S.S.53, 85 Kaymin B.P. 436 Koslitin Е.Л. 286 Kazakevloh M.Z. 86 Kozlova fi.D. 210 Kazantsev G.H. 122 Krapivln M.I. 449 KaEinakaya I.E. 445 Kvasnodubakaya S.V. 200 Seller C. 450 Kratz J.V, 235 Keller 0.1. 95 Xremlyakova N.Yu. 348 Kern S. 62 Krlvokbatskli A.S. 43, 209, 440 Keruohenko T.A. 420 Krot H.M. 179,210,352,359,360 KhalUn V.A. 263, 274, 275 Kbaiitonov Yu.P. 4T Krupa J.-O. 100 456 Krupitskii S.V. 243 Machulskii V.A. 339 Krylov V.H. 287 Kublca B. 335 Malafeer И.Р. 392 Kulawik 1.296, 303 Malikov D.A. 320 Kulawii J. 296, 303 Marchenko V.I. 353 Kulazbko V.O. 442 Marechal Le 203 Kuleahov N.P. 449 Mareev I.Yu. 124, 125, 214 Kulyako Yu.M. 331, 366, 401 Markov B.N. 85 Kulyukhin S.A, 239, 252, 260 Markov Q.S. 301 Kurtaaov O.V, 200 Markov V.K. 393 JCuz'mln ll.U. 393 llarq.uet-El.lls H. 74 Kuznetsov G.I. 371 MasMrov L.G. 236 Kuznetsov N.I. 200 Maslennikov A.G. 365, 398, 4О4 Kuzovkina E.V. 320 Maalova M.N. 449 Hasurlna I.I. 435 Lagutenkov V.A. 337 Mathews O.K. 164 Lahalle H.F. 100 Matoo A. P. 194 Lander G.H. 62 Matsui H. 160 Larlna K.P. 287 Matsui I. 113 Larina V.И. 204 Matsumura M. 177 Larroque J. 97, 146 Matveev L.V. 35 Xau K.H. 211 Matyukba V.A. 210 Lauria D.c. 450 Matyuahin E.A. 253 Lavrinovloh B.A. 345 Medehem B.A1. 406 Lazarev L.N. 342 Мегг E.R. 23 Lazarev S.D. 416 Meacheryakov H.M. 337 Lebedeva L.a. 215, 219 Meuris P.170 Lebedev I.A. 245, 366, 388 Mezhov E.A. 272 Lebedev V.A. 110 Michailova N.A. 403 lebedeva И.А. 396 Mikhailov I.A. 39 Lee D.M. 235 Leonov M.R. 204, 205- Mikhailov Yu.H. 184, 185, 193 Id Den Doc 231 Mikhalina T.V. 83 Hiknalko V.K. Liechtenstein A.I. 69, 70 83 Lienert K.H.235 Hikheav N.B.61,86,135.238,252,260 Lieaer K.H. 421, 426 tlikheera H.N. 267 Ling Daren 378 Mikheyev M.V. 337 Litvina M.N. 308, 310 Mikulski J. 296,303 Lobanov A.V. 298 Uilanov H.263,274,275 Lobafl O.P. 31, 210, 418 Mile* A.231 lomonoaav A.V. 315 Milyukova M.S. 320,322 Loong O.K. 62 Kinaeva N.A. 188 Lougheed R.W. 46 Mirokhin A.M. 315 Ludwig it. 274. 275 Mironenko M.V. 166 Lukjanova R.G. 435 Mironov 7.S. 78 Lumpov A*A* 142 Mishina L.A. 31 luo H. '67 Vlstrjukov V.B. 184,185,193 by В.И. 422 Hitaugaebira Т.Н. 206,410 Lyalyuehkin M.V. 172 Miyake 0. 177,186 457 Miyake И. 175 Omelyanenko B.I» 121 Hoblus S. 450 Opila J. 144 Hohamed A.A. 181 Orsatova I.I. 361 Molochnikova N.P. 350,368 Orlova 1.И. 193 Moore J.R. 217 Orlova O.A. 48, 50 Mordashova V.V. 446 Morris D.B. 225 Oabcrn R. 97 Osetrov 0.1. 53 Moaeev L.I» 419 Moahkov M.M. 301 Fagea M. 79, 91 Mosyazh V.M. 37 Palewaki I. 158 Mu Dehai 378 Panohenoo A.V. 435 Jluhlenweg U. 426 Panda C.R. 341 Mukherjee M. 877 Papkov A.S. 31 Mulak J. 77 Patil S.K. 247 Huninov A.L. 52 Pavlotskaya P.I. 427,443,445 Murray G.M. 95, Pavlova I.V. 420 Musikaa С 313 Pavlovloh O.H. 339 Muzychka ЬА. 57 Pazukhln E.M. 209 Hyasoedov B.F. 197,267,340,388,427, Pchelin v.A. 442 Hydlarz T. 144,158 Perelygin V.P. 429 Perepecb K.V. 108 Baegele J.R.14 Nal-Qi Y. 235 Peretrukhin V.P. 365, 404, 406 Naito K. 113, 174 Perevalov S.A. 245, 331 Nave S.E. 217 Perehlna V.G. 65, 72 Navratil J.D. 25 Peahkov A.S. 286 Naumov M.A. 392 Peterson J.R. 93, 95 Naylor A. 15 Petrov V.G. 182 Mefedov V.S. 87 Pevtsov S.V. 34 Nenarokomov Eh.A. 34 Piehler S. 84 Neaterova H.P. 310 Pikaev A.K. 383 Neumoev N.V. 392 Plkul V.P. 452 Hiese s. 408 Pilz И. 421 Nieae U. 408,431 Pirozhkov S.V. 442 Jllkiforov A.S. 6, 20 Piakarev P.B. 361, 363, 433 Nikitenko S.I. 377 Pleekaohevakii i.A. 85 Hikolotova Z.I. 305 Pokbltonov Xu.A. 342 Hikonov M.V. 359 Poletaeva I.L. 420 Nltchkov I.P. 122 Polkatisva H.L. 437 Horman M.R. 133 Popov I.B. 221 Novikov A.P. 267,348, 438 Popov S.O. 324, 328 Novlkov Yu.P. 340, 394, 395 Popov Yu.S. 138 Nurmia M.J. 235 Poadnyakov S.V. 182 Prakashan P.K. 164 Pribylova O.A. 311 Prokoahln A.D. 253 Oganeselan Yu.Ja. 47, 57 Proyayev V.V. 269, 317 Ohraiohl T. 162 Pruaakov V.N. 214 Okada I. 410 Puabkov A.A. 371 Radchenko V.M. 215, 219, 223 Schelokov R.H. 184, 185, 193 Radyuk R.I. 452 Seherbskov V.A. 250, 256 Rakhraanov Zh. 407 Scherbakove l.L. 250 Raspopin S.P. 122 Scherer U.W, 235 Ravsbanov R.M. 407 Schonhof or S. 450 Reddmann H. 75 Schpunt L.B. 256 Rod'kin A.P. 121 Sechoveky V. 130 Rpimana Т. 26}, 274, 275 Sadov V.P. 269,300,317, 344, 451 Renard 6h.V. 20, 392 Seleznyov A.G. 215, 219 Rezepov V.A. 371 Seleznev V.P, 182 Simskii-Koreakov A.A. 85 Semenov E.N. 403 Rizzo L. 118 Setrtyurin I.G. 401 Room S.S. 39 Sergeev A.V. 184, 185 Rodionov Yu.F. 442 Sergeeva E.I.120, 121 Rodyushkin S.P. 353 Serik V.P. 124, 125, 214 Rogozhkin V.Yu. 35 Sevast'yanov V.G. 200 Romanov V.S. 39 Shadrin A.Yu.311 Romanovekaya I.A. 382 Snalimott G» 84 Romanovskaya G.I. 396 Shamin V.I. 31 Romanovskii V.S, 243. 344 Sharopov O.U. 188 Homanovaky V.7. 342 Shashukov B.A. 451 Rosen R.S. 203 Shatkov V.M. 451 Roech P. 263, 274, 27? Shepel'kova M.P. 353 Rossat-Mignod .7. 62 Shevehuk Yu.A. 147 Rossbach H. 140 Sbibani S. 181 Rotmanov K.V. 373 Shllov V.P. 359,360,383 Rozen Л.И. 6, 20, 289, 292. 305 Shimoarev E.V. 223 Shkinev V.M. 350, 43B Rubisov V.N. 292 Shlok A.B. 70, Rubteov Е.И. 195 Soiokawa Y. 102 Runer I.A 86, 135, 238,252 Shpunt 1.В. 10a Ruein L.I. 315 Shubko V.M. 442 Ryabinin И.А. 214, 219 Shurkus O.V. 435 RyabukMn V.A. ЗЭ5 Shuahakov V.D. 215,219 Rybln A.H.420 Shvetsov ХЛ. 41, 330, 385, 442 Ryklyuk A.V, 47 Sidorenko O.V. 198 Ryzblnskii M.V. 390 Siekierskl S. 67, 249 Ryzkov M.V. 76, Silin V.l. 406 Sakanoue Ы. 447 Simon A. 171 Salamatin L.I. 231 Sinev M.Yu. 353 Samatov A.V. 272 Singh S. 341 Sandman T.A. 212 Sipin V.V. 136 Santoe I. 194 Sirotinin A.N. 392 Sarrio R.V. 95 Si trail S. 1S9 Sawant R.M. 247 Sklyarenko D.I. 402 Savelyeva N.I. 121 Skorovarov J.I. 315 Savonenkov V.G. 440 Skovorodkin II.V. 440 Schadel И. 235 459 Smetanin Eh.Ya. 20 Teterin N.E. 416 Smirnov A.N. 53 Tikhomirova G.S. 233, 279 Smirnov A.V. 254 Timofeev G.A. 126, 138, 375 Smimov Б.А. 136, 147 Tlmofeev l.P. 136 Smirnov K.E, 136 Timokhin S.N. 227 Smimov S.N. 43 Timonlna O.K. 414 Smimov v.v. 418 lOBhev М.Г. 188 Smirnov V.V. 441 Tran V.H. 130, 151 Smirnova E.A. 440 Iran Kim Hung 275 Smith G.S. 111 Travnikov S.S. 197 Smith B.H. 356 Treesh M.B. 398 Smulek W.S. 431 Troo R. 130, 151, 153 Sobolev I.A. 435 Trofimov T.I. 366, 438 Sokol E.A. 57 Troyanovaky Z.V. 272 Solovkin A.S. 298 Trukhlyaev P.S. 330 Solovyev I.V. 69, 70 Tsalon S,I. 29 Solov'yova G.V. 204, 205 Sood S.D. 116 Taarenko A.P22 22 Soulie E. 74, 203 Tsareva z.I.330 Spirlet J.С 79 Tsuyi T. 174 Starehenko V.A.. 37 Tu Shu-de 426 Staun Olaea J. 167 Turek K. 144 Steinkoplf Ih. 426 Turfcin V.I.418 Stepanov A.V. 53, 85, 390 Tiirler A. 235 Stepanov S.I..326 Teyryulnikova N.v. 330 Steteenko S.G. 429 Stirling w.G. 62 Ueno P. 171 Sudakov L.V. 172 Ueno K. 447 Suglobov B.H. 198, 236 Ulanov S.A. 99 Suraeva N.I. 72 Ul'Janov V.S. 315 Suski W. 144 Ustinov O.A. 253 Suzuki K. 102 Ostyugov V.G. 392 Suzuki S. 102, 206 Symona T.J.U. 429 Szegloweki Z. 233, 335 Vakhruahin A.Yu. 271271 Szytula A. 14S Valyunln B.S. 420 Varezhkina U.S. 322 Vaehman A. A. 419 Takahashi II. 206 Vaeilyev V.I. 223 Taleb B.H. 286 Vasiliev V.Ya. 215, 219, 373 Tamaki M. 160 Vaaideva Rao P.R. 164 Tamburini S. 261 Venugopal Y. 116 Tananaev I.G. 355, 360 Vladimirova II. V. 380, 332 Tatzy Yu.G. 398 Vlasov B.H. 363, 433 Taylor A. 97 Vlasov V.S. 292 Telnoy V.L. 204 Vigato P.A. 191, 261 Ter-Akopian G.M. 48, 50, 57 Vitorge P. 357 Teterin Eh.G. 397 Vobecky II. 285 Vokhmin V.G. 71 Zabolotskaya I.D. 446 Volyneta M.P. 36a, 395 Zakharkin B.S. 20 Vradii A.G. 392 Zakharov H.V. 419 Zantuti P. 340, 406 Wang Luhuan 283 Zenuyanukhina fl.A. 420 Wang Yani 378 Zhang Yanlin 283 Williams O.w. 60 • Zhao Aimin 2S3 Wilmarth W*R. 93 Zhiganov A..H. J1 YaMoehkin A.V. 393 Zhitikov B.L. 87, 227 Yagi M. 102, 206, И0 Zhuk L.I. 452 Yakimjv S.S. 414, 416 Zburavleva 8.1. 353 Yakovlev И.О. 333. 363, +33 Zilberman E.Ya . 37, 294 Vamamnto M. 447 Ziiamermann P. 235 Yamanaka S. 175 Zolnierek Z. 151 Yamashita T. 114 Zolotov Yu.A. 328 Yamaucni Y. 447 Zotov A.V. 121 Yazenko V.A. 339 Zuev B.K. 414 Yang D. 450 Zvara I. 9,54, 07, 227, 233 You-Oong-Hao 82 Zvereva M.P.416 Young J. P. 225 Yuaina V.G. 449 Yue Tungsheng 378 Yusov A.P. 179. 240, 241 CONTESTS Preface 3 Plenary leoturee 5 large Soole Production and Application. Synthesis of Superheavy Element a in Keaotlons with Heavy lone. 19 Blaotronlc Structure and Speotroaoopy .$9 Xhexnooynamlc Properties. 105 Solid State Physios end Chemistry 129 Solution Chemistry. . 229 toaljtioel Chemistry...... ЭВ7 Aotlnldee in Environment 425 Authors Index. 453 ^•S-JIij,^. Научное издание СБОРНИК ТЕЗИСОВ ДОКЛАДОВ МЕВДУНАРОДШЯ КОНФЕРЕНЦИИ "АКТИНида-89" (на англ.яз.) Утверждено к печати Институтом геохимии и аналитической химии им. 3.И.Вернадского АН СССР Редактор издательства Л.С.К аляпкина Художник А.Г.К о б р и н Художественный редактор А.В.З д р и л ь к о Технический редактор Н.В.В ишневская # НТК Подписано к печати 22.05.89.Формат 70x100/16 Бумага офсетная # I.Печать офеетнчя Усл.печ.л.37,7.Усл.кр.-отт.Э7,9.Уч.-изд.л.30,7 Тирая 800 экз.Тип.зак.ТЮ? 'Денз вр.20к.Зчкаэ8О* Ордена Трудового Красного Знамени издательство "Наука" II7864 ГСП-7, Москва В-485,Профсоюзная ул.,д.90 Ордена Трудового Красного Знамени 1-я типография издательства "Наука" 199034.Ленинград В-34.9-Я линия, 12 h