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Reviewa PapeB5 , rMb

Status of Transactinium Evaluated Neutro Energne Datth n yai Range

10"3 eV to 15 MeV

S. Yiftah, Y. Gur and M. Caner Department of Nuclear Engineering Technion-Israel Institut Technologf eo y Haifa, Israel and Israel Atomic Energy Commission Soreq Nuclear Research Centre Yavne, Israel

Abstract

Large amounts of transactinium elements will be produced in the next 2S years in thermal power reactors, fast breeders, test reactors, special purpose reactors, thermonuclear explosions and improved heavy- accelerators e ablb o evaluateo t e T . , predict, compute and judge the effects and uses of these elements, the nuclear commu- nity needs fully evaluated nuclea re use b dats nuclea a do t a r input to all computations and evaluations. The sixteen transactinium ele- ments and two hundred known to-date are divided into three groups eighd an , t main application area e mentionear s d from which needs can be derived for measurements and evaluations. Existing evaluations are tabulated and analysed, and following a WRENDA minus

CINDA descriptive equation, nine main conclusion recommendationd an s s are derived, amongst which a "world transactinium nuclear data evaluation program" and other specific items for IAEA future actions in this field.

1. INTRODUCTION

Large amounts somn ,i e cases tonhundredd an s f kilogramso s f o , transactinium elements will be produced, whether we like it or not, in 165 the nex year5 t2 therman si l power reactors, fast power reactors, test reactors and special-purpose reactors. These elements will affect the behavior and operation of the reactors, the cost of the power produced, the content and disposal of the radioactive waste, Some of these elements will be used in space missions, cardiac pacemakers, artificial hearts, various industries, and remote unattended sources of power.

On the other hand, improved heavy-ion accelerators capable of accelerating of all elements up to will enable the pro- duction of new and heavier translawrencium and transkurchatovium elements and enlarge the . Finally intense ,th e burst especiallf so y designed underground thermonuclear explosions will again serve to produce, instantly,

severaTransactiniue th f lo m isotopes.

able b evaluateo t eo T , predict, comput judgd effecte an eth f so these new elements, optimise their production, optimise their benefici- ary effects on reactors, evaluate their uses in different applications, minimise their contamination effects, minimis r canceeo l their long- term radioactive effect in nuclear wastes, the nuclear community needs fully evaluated nuclear data to be used as nuclear input to all these computations and evaluations.

2. SIXTEEN TRANSACTINIUM ELEMENT HUNDREO TW D SDAN ISOTOPES

Actinium being element number 89, sixteen transactinium elements are known to date, from 90 to 105. The sixteen transactinium elements include three naturally* occurring elements, , protactiniu uraniumd an m ,

* Evidence for the occurrence of -244 in nature has been obtained in U.S.A e 197th n 1.i Minute amount Pu-24f so 4 were e founth n di natural "as mined" bastnasite ore, a rare earth fluorocarbonate mineral. 166 eleven man-made transuranium elements, from o (Not ) .93

(No. 103), that complete the fourteen elements of the

series, in which the filling of the 5f shell takes place, and two

translawrencium elements, kurchatovium (No. 104) and hahnium (? , No. 105)

that continue the periodic table below hafnium and .

The sixteen transactinium elements, together with predicted locations elementsw ne f e o showa conventionaar , n o n e lperiodi th for f mo c table

in figure 1^.

s seei t nI thaactinidee th te considere b "heava n e ca sb yo t drare - earth- like" serie f elemento s s analogou e lighth to t srare-eart h series, the f electro4 whicn i ,e th h n shel s i filledl iden a , a con-

ceived by Seaborg in 1944 which was the key to the discovery of several

of these elements. Some of the names reflect the actinide-

analogy. The actinide versus the lanthanide ;

after Pierre and Mary Curie, by analogy with , after the Finnish

rare-earth chemist . J Gadolin, ; after Berkeley, California,

analogous to ,, derived from , Sweden, where so many of the

early rare-earth minerals were found.

Figure 1 also shows a possible "super-actinide" family, starting

with element No. 122 which can again be considered as a superheavy-rare

earth-like serie f elementso s , resultin- g4 1 fro e filline mth th f o g

membe f subshel6 r f electronso l .

It can be noted in Fig. 1 that all the transactinium elements known

today, wit e exceptioth h (Nou K a (Nof . 104no H d . 105))an , belono t g

the actinide series.

About 200 isotopes of the 16 transactinium elements are known to

date. Onl isotopes2 7 y r abouo , a thirdt , have half-lives higher than

one day. Out of these last 72 isotopes again a third, 24 isotopes, have (2) evaluated neutron data reporte . n CINDThesdi 5 7 Ae las isotope4 2 t s

167 include the 5 main fissile and fertile isotopes (Th-232, U-233, U-235, U-238, Pu-239 t subjec)no discussioo t prograe presene th th n f i no m t meeting.

Numerically speaking ) transactiniu24 have - ,w 2 e (7 the 8 4 nm isotopes with half-lives higher than one day that do not have any evaluated data, at least any that are reported in the last issue of CINDA,

published April 1975.

Several questions arise.

1) Are available evaluations not reported in CINDA 1975? 2) Are the evaluations fairly recent and do they contain all experi- mental information? Do some of these evaluations need updating?

) 3 Doenucleae th s r community need evaluation existint sno g today? With what priorities? e thesAr e ) need4 s world-known, documente d coordinatedan d d relatean , d

directl o specifit y c applications?

5) Are evaluations needed for isotopes having half-lives shorter than

one day?

6) Can a consensus be reached as to what evaluations are needed, with what priorities a coordinated als n an ,o d international "division of labor" on performing the needed evaluations within a specified

of time?

enougo D h) 7 experimental measurements exist whic forn basise ca hth m , together with theoretical model calculation d systematicsan s e th f ,o needed evaluations?

This lis questionsf o t , whic probabln ca h e extendedyb , wil e deallb t with during the whole of this meeting, and presumably also after the meeting.

168 This paper is an attempt to give partial answers to some of the above

questions.

3. THREE GROUPS OF TRANSACT1NIUM ELEMENTS

The sixteen transactinium elements known to date can be divided into three groups, as shown in Table I.

Group I - 5 elements, 90 - 94, thorium to plutonium. elements6 Grou- I - 100I p 5 ,9 , americiu fermiumo t m . III - 5 elements, 101 - 105, mendelevium to hahnium.

Group I , (90 - 94), includes the main fissile and fertile isotopes that presene forbasie th th mf o st nuclear technology. Thorium, protactiniud an m

uraniu naturalle ar m y occurring. Neptuniu plutoniud an m m were discovered in 1940 - 1941, when the whole present nuclear technology was born. The five elements of this group include 82 known isotopes of which 37 have half-lives highe f theso risotope7 9 3 e1 tha e dayr on nFo .s evaluations exist.

Group II , (95 - 100), includes six elements which were discovered three bth y e basic method f transactiniuso m elements productionse ,th firs yieldino tw t g neutron-ric thire th dd neutron-deficienan h t :

) Multipl(a e neutron captur resula s a eintensf to e neutron bombardment over long period f tim o sn differen i e t type nucleaf o s r reactors (power reactors, test reactors, special-purpose reactors).

) (b Refinemen thermonulceae th f to r explosion method where suitable targets are subjected to intense bursts of in a very short period of time (milliseconds).

Fluxe d integratean s d fluxe r transactiniufo s m nuclides productioy nb successive neutron captur showe ar eTabln no e II.

169 ) (c Bombardment with heavy ions, from heavy-ion accelerators.

x elementsi e O th f fgrou o s p II, one, americium discoveres wa , d

(1945a resul s a f )irradiatio o t f plutoniuno m with neutron nucleaa n i s r

reactor (method a). Three, curium, berkeliu californiud man m were dis-

covered, respectively, by bombardment of plutonium with ions

(1944), bombardmen f americiuo t m with helium ions (1949 bombardmend an ) t

of curium with helium ions (1950) (method c). and , on the other hand, were discovered unexpectedly in 1952 in investigations of e corath l e bottoBikinth f mo i atoll afte e firsth r t bomb test

(method b). The six elements of group II include eighty known isotopes, of

which thirty-four have half-lives higher than one day. For only five

of these (Am-241, Am-243, Cm-243, Cm-244, Cf-252) evaluations exist.

, Grou(101-105) I II p , includes five elements f whico l hal ,wer e discovered by bombardment with heavy ions. Medelevium (101) was

discovere n bombardmeny 195i db 5 f einsteiniuo t m with helium ions. s discovere(102wa ) n 195i dbombardmeny b 8 f curiuo t m with

ions. Lawrencium s discovere(103wa ) n bombardmen196i dy b 1 t of with boron ions. Kurchatovium (104) was discovered in

196bombardmeny b 4 f californiuo t m with carbon iond alsan so curium with -18 ions. Hahnium (105) was discovered in 1970 by bom- bardmen f californiuo t m with -15 ionalsd an so berkelium with oxygen-16 and oxygen-18 ions.

The five elements of group III include 33 known isotopes, of

which only one, mendelevium - 258, has a half-life of more than one day, actually 53 days. This surprisingly long half-life for this groumaky t i epossiblpma e eventuall o isolatt y e elementh e t mendelevium in macroscopic quantities. Three other isotopes, Md - 257 has a half- minutese 7 5 th l 9 minutes7 lifAl 7 25 f . 5. o - e 6 d 1 25 M , - d M , others have half-lives of or less. 170 Table I

The Three Group f Transactiniuo s m Elements

Number Known No. of Isotopes Atomic of isotopes iso- Evaluated Group .No. number known with topes Element evalua- (CIND) A75 iso- T >ld topes l/2i/ ^ ted (CINDA 75)

1 90 Thorium (Th) 20 7 1 232

2 91 Protactinium 18 6 2 3 23123 , (Pa)

3 92 Uranium (U) 15 9 7 232, 233, 234, 235, 236, 237, 238 I 4 93 Neptunium (Np) 14 6 3 237, 2389 ,23

5 94 Plutonium (Pu) 15 9 6 236, 238, 239, (82) (37) (19) 240, 241, 242

6 95 Americium (Am) 13 4 2 241, 243

7 96 Curium (Cm) 13 10 2 4 24324 ,

8 97 Berkelium (Bk) 9 5 II - 9 98 Californium (Cf) 16 8 1 252

10 99 Einsteinium (Es) 14 5

11 100 Fermium (Fm) 15 2 (80) (34) (5)

171 Number Known No. of Isotopes Atomic of isotopes iso- Evaluated Group No. number Element known with topes iso- evalua- (CINDA 75) topes Tl/2>ld ted (CINDA 75)

12 101 Mendelevium (Md) 10 1 13 102 Nobelium (No) 9

III 14 103 Lawrencium (Lr) 6

15 104 Kurchatovium (Ku) 5 16 105 Hahnium (Ha) 3 (33)

Totals 195 72 24

s cleaIi t r froe abov th md fro ean m glancin Tablt a g thaI ee th t main evaluation work to be done is in group II.

4. MAIN HBED^FOR^RANSACTINI^NUCLEAR^ATA obvious i t i sf I thamaie th tn bi e reasogth efforr nfo produco t e transactinium elements and to discover new ones has been to increase our

understanding of atomic and nuclear structure, it should be as clear that a big effort in measuring transactinium cross sections and performing complete nuclear data evaluation thesr sfo e isotope bee s wild s ha nmotivatean e l b d neede b th yactuaf so l specific applications.

After sketching the large-scale panorama of the 200 known isotopes of the transactinium elements therefors i t ,i e logica introduco lt e eth

dimension of actual applications.

172 TablI I e Fluxe d Integratean s d Fluxe Transactiniur fo s m Nuclides

Production by Successive

Irradia- Integrated flux tion time flux Method _2 Remarks , -1 2 - <|>(nc±r m sec ) At 4>At(nc) m

Power typical PWR iox 15 31. 1 year 4.7X1020 thermal Reactors typical BWR iox 3 13 1 year 9.45x I02° neutrons typical HWR 0.5 x io14 1 year 1.58x IO21 relatively

Special HFIR iox 3 15 1 year 9.45x IO22 higher * Reactors Savannah x io6 15 1 year 1.89x IO23 capture (thermal cross - high -flux mode section operation)

Thermonuclear 31 6 25 fast neutrons >io <10" sec io relatively Explosion lower °Y 26 27 Cosmological s Process MO16 'vlO year io -io Nucleosynthesis 27 27 Production r Process <\>>io 1-100 sec >io

Production of Cf-252 requires of at least 1 - 2 - 15 3 x 10 ncm sec . The flux value for HFIR is the central region perturbed flux (with Pu-242 target material, for instance). In five reactor experiments performed at SRL for testing and adjustment of their consistent transplutonium multigroup cross sectio t (sese n e below), integrated fluxe betweef o s n 2.40 1 7 x 20 23 2 and 1.2 0 1 n/c2 x m have been reported (with exposure times ranging from 165 to 850 days).

Of course the main applications are the uses of the main fissile and fertile isotopes in thermal power reactors and nuclear explosives, which whole forbasie th mth ef s o presen t nuclear technology. 173 r thFo e purpos thif eo s meetin orden i gaio d rt g an n perspectivee ,w mentio followine th n g eight main areas from which derive e needb n r sca dfo

nuclear data measurements and evaluations for a large number of the trans- actinium isotopes.

a) The nuclear fuel charge for fast reactors; plutonium produced as by-

product from thermal power reactor operation, will consist of maybe 50 % of

the higher plutonium isotopes Put Pu, Pu. A typical 1000 MWe fast power reactor core contains 3 tons of plutonium. Half of this plutonium, that

is 1.5 tons, will consist of Pu, Pu and Pu. If the plutonium has been

stored for a few years, waiting for the fast reactors, there is an appreciable buildup of Am because of the 15-years half-life of Pu. The presence of O>1T Am in the fuel implies that O/1OA m and O/IOCm will be produced during reactor operation. These facts and figures illustrate the major importance of fully evaluated nuclear data of these actinide isotopes for the study, design, static d dynamicsan fasf so t reactors v '', right frovere (3-7mth y) beginning.

(b) Long burn-Up Fuels (up to 100,000 MWD/T) of fast reactors will

accumulate relatively large amounts of transplutonium elementss as these increase with the burn-up.

The effec thesf to e element behavioe th n o sfasf ro t reactors should and woul e carefulldb y studienecessare th f di y nuclear data become available.

) (c Long-lived containe radioactive th n di e wastes thermaf *o l reactors, fast reactor reprocessind an s g plants could possibl transe yb - muted into fission product other o s r elements thereby helping solve th e radioactive waste problem. This "actinide wastes recycle" requires a neutron source which might be the same reactor producing the wastes or a specially designed burner reacto ever ro fusiona n reactor ' 1 24 3 (2

See Appendix 174 Evaluated data are needed to predict in advance the amount and nature of

actinide wastes that will be generated and to analyse and test the pro-

posed recycle schemes, much before we have any proven technology for se-

parating and recycling actinides. alpha-particle-emittine (dTh ) g 238Pu, 242 244 d beinCe Cman d mar an g wil widele lb y use heas a d t source auxiliarn i s y electrical power systems for satellites, space probes, cardiac pacemakers, artificial heartsd ,an remote unattended applications. One interesting example occurred in 1967 on the moon. The surveyor V spacecraft landed on the moon and performed a chemical analysis of the lunar surface. The analysis was done using a 242 100 mCi Cm alpha-particle source produced by neutron irradiation of ?41 "Am energs A . y detectioe markerth r sfo n equipment 6.alphae V 4,th Me - particl sourcs smala E f uses eo l e wa d ^ ' .

havin, Pu Th specifia ge 238 c power W/5 outpug0. whicf o t h drops

very slowly becaus lons it g f halfo e -year6 8 lif f so euses ,i hig n i d h power radionuclide batteries in remote locations and in very low power batteries for cardiac pacemakers .

Pu can be produced in a reactor in two ways, by irradiating either O *?"7N p or "741 Am, The two 2 *^8Pu production chains which emphasize the cross sections significant to the production process are shown in figure 2 (8).

(e) Californiu 2 constitute25 - m mose th st intense, compact sourcf eo neutrons known spontaneoue Th . s fissio nucleis it n f o abouf deca)o % t(3 y

fj r o Q 2 mg (1 Curie) of Cf yields 4.4 * 10 neutrons per . 1 gram of 2 25 oco 19 Cf emits over 10 fission neutrons per second. Cf, which has a half lif f 2.6o e 5 yearswild an widele lb s ,i y use varioun i d s fields including cancer radiotherapy, neutron radiography, neutron activation

analysis and hydrology.

175 productiof C e Th n chai252n showin crose th g s sections significano t ro-\ the production process is shown in figure 3 ^ J „

) (f Starting material productior fo s usefuf no l actinides

We have already mentione7 23 d 241A m and Np as starting materials for o "z o the production of Pu. Am is extracted from stored reactor plutonium. During storages convertei u P ,bety d b rate a f th decao e t a y m A into 244 abou t m i r yearC s5- pe sproduce . d mainl y speciayb l irradiatiof no reactor plutonium where Pu, Pu and Pu fission or are converted into Pu. After separation of the fission products Pu becomes the 3 24 244 starting materia r irradiatiofo l d an d conversiou P an n a vi n m C into Am. Cm and Cm can also be formed from Am by successive neu- tron formes i capture f C d m afteC fro. mr 25eigh2 t consecutive neutro244 n 252 captures. Under neutron irradiation yieldf C ,s einsteiniua n i d man second step, fermium,

257Fm decays predominantl alphy yb a particle emission wit halfa h -

life of about 100 days which makes it a convenient isotope to study.

o r7 Fm is the heaviest isotope both in and which is available in sufficient quantity to obtain reliable counting statis-

C9 Q tics. The 380 microseconds half-life of Fm leads to the conclusion

that nuclei heavie cannorm F that n effectivel257 producee b y n nucleai d r

reactors .

Q O O O T O 'ZfiO (g) Radioactive contamination chain Pu, U, Th

9 \f\ 2^2 99 R A well known radioactive chain is Pu a ^ U a^ Th a ^ 2.85y 72y 1.91y

224 220 216 212 RD a q RD n q DPo q 212Pb 3 /1ZBi 3.64d 56s" 0.15s 10.641i 60.6m

212n 20 8n, 46s

176 sees Ii t n tha nuclidel tal s following e shorTar h t lived. 22Man8 y of these are powerful gamma emitters, and raise important contamination 9 l^f) *? ^f\ J *^R problems due to U in spent reactor fuel, Pu in Pu heat sources, Pu in recycled Pu for thermal and fast reactors, U in U. Materials contaminated with surprisingly small amount f thiso s radio- active chain require remote handling behind shielding.

Diffusion cascades can be contaminated by spent reactor fuel con- 232 taining U. Members of the chain are formed and deposited on process surfaces.

238 , , . ,. __. 237., . ^ ... 236 Pn u made by irradiating Np in a reactor is accompanied by PDu

e forme(n,2nth y b d) reaction.

237 236,, „ 236 XN7 p n,2n0 ^ Np g nPu a *" * 2.85y an s i thereford e unsuitabl r cardiafo e c pacemakers r thiFo s . application 238 241 the alternative route of Pu production via Am should be used.

970 9 •?/: Cross section requirements for the production of U and Pu are the 2 (n,2n23 ) cros 3 s23 sectio 2 23 n o f7 23 Np, U, Pa and Th with an accuracy

"77 9 ?£9 *Z9 9 of 10% (5% for Th), U(n,Y) with an accuracy of 5%, U(n,Y), with an accuracy of 10% and (n,cx) of U and Pu with an accuracy of 10%.

(h) Criticality of actinide elements

heas a tm C sources d e application welan Th s ,a s u a lP f o s application americiuf so othed man r actinides require knowledge th f eo criticality limits, especiall effecte th y moderatinf o s g materialst I . n TO bees ha n calculated r instance,fo , tha e criticas tth i u P l mas f o s 9 TO about half that of Pu.

For criticality evaluations one needs to know the Pu and Cm (n,f), u, (n,y)j (n,n'), (n,naccuracn amerie a th o )t d -abouf an o y % t5 cium isotopes cross section accuracn a o t s maybf yo e 10%.

177 These requirements become more important if one takes into account the large amounts of actinide isotopes to be produced in the future. One such estimate, for illustration purposes, is given in Table III ^ .

TablI II e

Annual Productio Actinidf no e Isotope 198- s 7 (91

U.S. (tonnes/year) World (tonnes/year)

0 43 0 16 Fission Products

0 6 U-23 2 U-23n 2 (i 6 U-238$ 5 )

Np - 237 2.3 6.3

Pu - 238 0.6 1.6 Pu - 239 40 110

Pu - 240 13 36

Pu - 241 6.7 18 5 2. 9 0. 1 24 A- m

1 4. 5 1. 2 24 - u P 2 24 C- m 0.03 0.08 Am - 243 0.6 1.7 3 0. 1 0. 4 24 C- m

o finT d evaluation f transactiniuo s m shoule on s d first look g evaluatebi e ath t d nuclear dat avarioue fileth f o ss countrie d laboraan s - tories working with actinides, thas i t

) ENDF/B-IV1 , U.S.A.

2) UKNDL, United Kingdom

3) KEDAK, Germany

4) LLL, Lawrence Livermore Laboratory, U.S.A. 5) SRL, Savannah River Laboratory, U.S.A.

178 Table IV

Actinide Evaluations

1 No. Nuclide Half-Life ENDF/ UKNDL 1 KEDAK^ LLL^ SRL<3> OTHER T B-IV | i-L / /-z> j i ;i " 1 Pa-231* 3,,25>104y 1 +(1970) GA-7462 \ i (1967) [ *• 2 Pa- 2 33 27d + (1970) i GA-7462 \ (1967) I ——————————— ————— > —— . — * t ' -' 3 U-232 72y + (1970) i * n 4 U-234' 2,44x10 y -(1967 + (1970) +•(1972) 1

„ Q x 5 U-236 2i,342 10 y + (1971) + (1970 + (1972)

* 6 U-237 6.75d + (1970) + (1972)

7 U-239 23.5m + (1972)

6 8 Np-237* 2J14xl0 y + (1973) +(1970) +(1973) it 9 Np-238 2.12d + (1970) * 10 Np-239 2.35d

•it 11 Pu-236 „2 85y + (1970) A 12 Pu-238 87.8y + (1967) + (1967) + (1974) +(1972) % 13 Pu-240 6540y +(1970) +(1972) + (1972) * 14 Pu-241 15y K1973) +•(1970) + (1973) + (1972)

15 Pu-242* 3.87xl05y + (1967) + (1973) + (1975)

16 Pu-243 4.96h + * 17 Am-241 433y +(1966) +(1970)

18 Am- 242 16o02h •t

19 Am-242m 152y + (1972) - sere e mark NO. 4 * 20 Am-243 7370y +(1966) + (1975)

179 No. Niiclide Half-Life ENDF/ UKNDL KEDAK^1-1 LLLC2> SRL(3^ OTHER T B-IV 1/2

21 Cm- 242 163d +(1970)

22 Cm- 2 43* 28y

23 Cm- 244* 17.9y + (1967) +

24 Cm-245 8.5><103y +(1974) +

25 Cm- 2 46 4.76xl03y +

26 Cm-247 1.54x!07y +

27 Cm- 248 3.5><105y +

28 Bk-249 Slid +

29 Cf-249 35 2y +

30 Cf-250 13, ly +

31 Cf-251 ^ 900y +

32 Cf-252 2.63y ' + (1974) + 33 Cf-253 17. 8d +

34 Es-253 20.47d

Remarks: * nuclide9 1 e Th s marken asterisa y db k have evaluations listed

in CINDA 75.

(2") A second referenc o studt e y woul e CINDdb 5 ^ 7 Ae Compute th , r Index of Neutron £ata, which contains bibliographical references to measurements, calculations, reviews and evaluations of neutron cross-sections and other microscopic neutron data. CINDA is published yearly on behalf of the USA National Neutron Cross-Section Center, the USSR Nuclear Data Centre, the

NEA Neutron Data Compilatio nIAEe Centrth A d Nucleaan e r Data Section. In future, it will apparently be published once every two years. Table IV lists the actinide evaluations known to the authors to be

180 included in five evaluated files as well as those listed in CINDA 75. e yeaTh r afte sige rth nindicate+ evaluatione th e dat f th so e . Where mentio o theryear-authorn e s th i e f no s coul t ascertaidno evalue nth - ation date. This omissio easiln ca n e correcteyb d later.

Another paper prepared for the present meeting entitled "A Survey of Cross Section Evaluation Methods for Heavy Isotopes" gives details of the nuclea re formalism modelth d an s se thermal th use n i d , resolved reso- nances, unresolved resonances and fast energy ranges, in some recent

evaluations.

(1) The KEDAK column includes evaluations of Pa-231, U-232, U-234, U-236, U-237, Np-237, Np-238, Pu-236, Pu-238, Am-241 and Cm-242

done by B. Hinkelmann , and evaluations of Pu-2381-238, PPu-240u s (12, ,13 Pu-24 Pu-24d 1an 2Yifta , Cane S . donM d y heran b

) (2 Lawrence Livermore revisionL LaboratorLL e th . n i s y

evaluations: a,f, of U-234 revised 1974; a,,r and a n,3,n of U-236 revised 1974; a. a and a . of Pu-238 revised Jan. 1975 \ f, n,y e£

) (3 Savannah River Laboratory

(4) A partial evaluation of fisssion and capture cross sections form 0 to 5 MeV has been done in Saclay, France. The results are given

imultigroua n p form adapte thermao t d l reactor study. These cross sectionw checkeno e sdar with irradiated fuel analysis C17)

Examining Table IV some general remarks are in order.

It can be seen clearly that ENDF/B-IV includes evaluations of 11 actinides

of which only three have been performed after 1972 (similarly KEDAK includes

evaluation actinide4 1 f so whicf so h only four have been performed after 1972). bees ha nt I therefore recognised (see also Hainan's review paper A-l) thae tth

ENDF/B-IV data files for Americium, Curium, Berkelium and Californium are ina-

dequate or nonexistent. New actinide evaluations are underway at SRL, Hanford

181 (Schenter) and LLL (Howerton). These are shown in table IV and will be included

in ENDF/B-V whicr ,fo filha Actinidf eo e Nuclear Dat currentls ai y being pre-

pared. This file will also include evaluated decay data by Dr. Reich.

ThL (LawrenceLL e Livermore Laboratory) library doe contait sno n resonance parameters.

The SRL (Savannah River Laboratory) library is more than an evaluated libra- nuclide5 1 productioe e th th n si f r o y n chai nthroug u ActuallP . froEs m h y 3 25 2 24

the proces gon s stee sha eon p furtheevaluaten a d ran d consistent transplutonium

multigroup cross section set has been obtained '

The data are currently in a format similar to the HAMMER format and consist of

resolved and unresolved resonance parameters (up to 10 keV) and smooth 84-group

cross sections that span the energy range from 0 to 10 MeV with a thermal cutoff

at 0.625 eV. The 30-group THERMOS structure is used for the thermal region and the

54-group MUFT structur epithermae th uses r ei fo d l region 84-groue .Th p sets have

also been collapse group7 3 therma2 o epitherma5 t d2 (1 s d lan l groups) whicy hma

be used to reduce computer time. The data have been tested through comparison of

measure calculated dan d production yield therman si nead lan r thermal neutron

spectra. Available data above 10 keV have been included, but have been neither

evaluate testedr dno date bein.s Th ai g put, along with some additional actinides,

intENDF/e oth B forma wild tan l probabl made yb e available throug Nationae hth l

Neutron Cross Section Center, Brookhaven.

Generally, the concentrations of actinide nuclides predicted with the

newly-formulated consistent set are within ±10% of the experimentally-

measured concentrations.

/ T Q\ Table V lists the values of the 2200 m/s fission and capture cross

sections, the g-factor which is a convenient measure of the departure from 1/v

dependenc resonance th d ean e integral Id an wit sI thermaha l cutoff fo C J- grouo tw pr calculation0.62Fo . 5eV thermae sth l value used proe shoulth -e db

duct of the 2200 m/s cross section and the g-factor.

182 Table V

Characteristic Cross Sections from the SRL

Multigroup Data Sets *• ' I a2200 2200 c c °£ >0.625 eV >0.625 eV (barns) (barns) g- factor (barns) (barns) Isotope

242Pu 18.7 0 1.0 1,280 4.74

243Pu 87.4 180 1.0 264 541

243Am 74.4 0 1.015 2,159 3.4

244Cm 10.0 1.5 0.995 585 17.1

245Cm 383 2161 0.971 104 766 246 Cm 1.4 0.17 1.0 119 10.0 247 Cm 58.0 72.3 1.0 500 761 248 Cm 2.89 0.11 1.0 251 14.7 249 Bk 1600 0 1.0 4,000 0

249Cf 495 1720 0.969 111 1863 250 Cf 1701 0 1.0 11,000 0 251 Cf 2849 4801 1.0 1,600 5400 252 Cf 20.4 32.0 1.0 43.5 110

253, 12.0 1100 1.0 12.0 2000 253 Es 155 0 1.0 7,300 0

Another general remark concernin e followingth g Tabls i V I e : while some nuclides have been evaluated only once and appear in only one of the big evaluated data files, others have evaluations in two, sometimes three, of the big files. In this case several problems arise: what are the differences betwee e evaluationth n betweed an s e multigrouth n p sets obtained from them? Will physics and other parameters of the reactors calculated using the different files be different? How big is the difference?

183 To shed some light on these problems a comparative analysis of the

various evaluated files should be performed. The results of the analysis

ca ne detaile th the a tooe user nb s fo a ld d examinatio f discrepano n t data.

Examples of comparative analyses of this type are given in references (19-221

Generally speaking, it seems reasonable to assume that most evalua- tions performed before 1972 should be reevaluated, taking into account

new experimental measurements and better theoretical model calculation

techniques.

6- WRENDA_-=CINDA_=_?

As is well known, since 1972 a World Request List for Nuclear Data Measurements (WRENDA issues )i d annuall e IAEth A y Nucleayb r Data Section on behalf of the U.S.A. National Center, Brookhaven, the European (NEA) Neutron Data Compilation Centre, Saclay, the IAEA Nuclear Data Section ,USSe Viennth R d Nucleaaan r Data Center, Obninsk. e firsth tWRENDs editiowa printe4 e 7 b A o t n d frocomputerizee mth d data request file maintaine e IAEth A y Nucleadb r Data Section.

IAEA also publishes CINDA, the Computer Index of Neutron Data, the

last issue being the two volume CINDA 75. CINDA contains bibliographical references to measurements, calculations, reviews and evaluations.

In principle, if the two IAEA publications, WRENDA and CINDA, are

complete and up-to-date, the complicated - sophisticated equation of

WRENDA - CINDA = NUNDA

should constitute a guide for the needed and unavailable nuclear d_ata.

e firsTh t conclusio jusf no t lookinequatioe th t glancingd a nan g o recentw e tath t issue WRENDf o s d CINDan A s thai A t ther soms i e e

184 assymetry. While CINDA contains also evaluation nucleaf o s r data, WRENDA lists only measurements.

We recommend WRENDo therefort "quantityd e ad Ath o t e " EVALUATION and put under this heading evaluation requests recommended by the present panel and in future by Member States, This way WRENDA will become also a World Request List for Evaluated Nuclear Data.

Another assymetry is in the opposite direction. WRENDA rightly lists mucn ,i h detail accuraciee ,th s require varioue th f o ds requests. Whe e lookmeasuremena on np u s t report liste CINDAn i d e finds,h , usually, listed explicitly, the uncertainties attached to the measure- ments. Not so if one looks up evaluated data listed in CINDA. Also the main big evaluated nuclear data files do not contain uncertainties.

s beeItha n recommended before that evaluations should contain rough estimate uncertaintiee th f o s recommendee th n i s d data agree W . e with this opinio furthed an n r sugges te futur th tha n ei t these estimates be included in the "general information" section of the evaluated data files.

As examples of recent requests in WRENDA, we mention the requests of G.A. Cowan, Los Alamos Scientific Laboratory, for the fission cross sectio isotope2 1 e energ f th o n n yi s range 10-10 witV n accurac0ke a h y isotope2 1 prioritd e an Th % s o , 10 f1 yare : Fm-2S7f Fm-255, Es-2S3,

Cf-252, Cf-250, Cf-249s Cm-248, Cm-247s Cm-246, Cm-245, Cm-244, Cm-243, Som thesf o e e cross section needee ar s evaluato t d productionf C e , while the cross section of Cm-243 is needed to evaluate Cm-244 production.

As another exampl mentioe ew requeste nth Dessawe. G e f th o s f ro Savannah River Laborator capture th r efo y cross sectio isotope3 1 f o n s in the energy range 25,3 meV to 10 keV with an accuracy of 10% and priority 1 or 2„ The 13 isotopes are: Cf-253, Cf-252, Cf-251, Cf-250, Bk-249, Cm-248, Cm-247, Cm-246, Cm-245, Cm-243, Cm-242, Am-242 (152 year isomer), Am-241 Dessawe. G . r also request totae th s l cross sectiof o n 185 several californium, berkelium, curium and americium isotopes in the same energy prioritied rangan , 2 e % r o wit20 n 1 accuracs- a h 0 1 f o y

As a third example, again a large bundle of requests, we mention e request th . Matsunob. YumotH R d f o san o e f fissioJapano th u r fo n,

and capture cross section isotopes2 2 f o s , from Pu-24 o Cf-254t 3 n i ,

e energth y range from therma MeV0 1 o ,t lwit h accuracie - 20% 5 .f o s Fourteen of the isotopes requests have priority 1 and eight priority 2,

These request e motivatear s reactoy db r burnup calculation estimad an s -

tio f trans-uraniuo n m nuclide build-u n speni p t fuelneutrod an , n

shieldin f spent-fuego l transport cask.

The WRENDA definitio f prioritieo n e followingth s i s :

Priority 1 - Nuclear data which satisfy the criteria of priority 2 and which have been selected for maximum practicable attention, taking

into accoun e urgencth t f nucleao y r energy programme requirements. Priority 2 - Nuclear data which will be required during the next few e applieyearth n i sd nuclear energy program. Priority 3 - Nuclear data of more general interest and data required e bod f informatioth o y o t fil t ou l n neede r nucleafo d r technology.

The above accuracies of 10 - 20% can be compared with much greater ones, in the range of 2% - 1% and even as great as 0.1%, requested for v in the of Cf-252, and for the energy spectrum

of Cf-252 neutrons, as illustrated in the following short tables.

?• Conclusions

(1) Becaus f theio e r major importanc s fuer a fase fo l t reactore th s

higher plutonium isotopes Pu-240, Pu-241 and Pu-242 (together with Pu-239 and U-238) should have at all times exact reliable up-to-date evaluations, to be revised and updated at regular intervals of two

o thret e years accurace e higheTh th . f yo r plutonium isotopes should 239 238 not be less than that of Pu and U.

186 maie (2Th n ) evaluatio e fouth r n i e don elementb wor s i eo t k f o s

Group II, americium, curium, berkelium and californium. Group I

elements have been extensively evaluated. Grou I elementII p s have extremely short half-lives and exist in minute atom quantities. For

Einsteinium and Fermium, the heaviest elements of Group II, few

requests and relatively few measurements exist. The four elements,

americium, curium, berkeliu d californiuman m combine th som f o e major application need f lono s g burnup fuels, long-lived actinides n radioactivi e wastes, heat source n auxiliari s y electrical power * * system r spacfo s , emedica l useremotd an s e unattended application, s

e anmultiplth d e use f californium-252o s , together wit s productioit h n

chain.

(3) The four elements, americium, curium, berkelium and californium

have 51 known isotopes of which 27 have half-lives of more than one

day.

The complete nuclear data evaluation f theso s isotope7 2 e s should constitute "the world transactinium nuclear data evaluation program e sponsoreb o t " coordinated an d internationan a n do l basis

e Internationabth y l Atomic Energy Agency,

(4) From the point of view of applications, it seems that out of the

2_7_ nuclides of the "world program" the following 14_ nuclides are the

most important: Am-241, Am-242m, Am-243, Cm-242, Cm-244, Cm-245,

Cm-246, Cm-247, Cm-248, Bk-249, Cf-249, Cf-250, Cf-25 d Cf-252an 1 ,

If further priorities are necessary, first priority should be

assigne e evaluatioth o e t dfollowin th f o n g 6^ isotopes: Am-241,

Am-243, Cm-242, Cm-244, Cm-245 and Cf-252,

generaln I (5 )s i advisabl t i , e that two separate evaluation done b s e

o-c each rmclide e criticallb , o t thes o tw ey compare analysed an d n i d

* together with Pu-238 187 various ways, in order to discover inconsistent and discrepant data

and to improve future evaluations.

(6) Comparative critical analysi f differeno s t nuclear data filed an s

evaluations should be sponsored by the International Atomic Energy

e benefi l Agencusersth al r f o fo yt.

(7) At the present stage of nuclear technology and applications on

one hand, and the relatively important world-wide nuclear data measure-

ment programs on the other, it is reasonable to consider, in general,

that the half-life of a good reliable nuclear data evaluation should e morb t e no than three years l evaluationAl , s shoul e checkedb r fo d revision r completo s e reevaluatio t leasa t three-yeaa - t- n r

intervalso

(8) WRENDA e worlth , d request lisr nucleafo t r data measurements

should become a world list for evaluated and measured nuclear data.

Users should specifically request nuclear data evaluations needed.

The requests shoul e weldb l documente related an d o specifidt c

applications.

l evaluation(9Al ) s should contai t leasa n t rough estimatee th f o s

uncertainties^ in the recommended data. These estimates should be

included in the "general information" section of evaluated data files.

References

(1) G.T. Seaborg, "Annual Reviews of Nuclear Science", Vol. 18, p. 96, 136 (1968).

(2) CINDA 75, Vol. 2, IAEA, Vienna (1975).

(3) D. Saphier and S. Yiftah, Proceedings, International Symposium on Physics of Fast Reactors, Tokyo, Vol. Ill, pp. 1491 - 1512 (1973).

. Yiftah(4S ) , Physic f FasIntermediatd o s an t e Reactors, Vol, II . 0 (1962)27 - 7 . 25 IAEA . pp ,

188 . . ShaviYiftahS G d ) an v (5 , Nucl. Appl 3 (1967)21 . , _34 ,.

(6) D. Ilberg, D. Saphier and S. Yiftah, Nucl. Technol. 24_, 111 (1974).

(7) D. Ilberg, D. Saphier and S. Yiftah, Trans. Amer. Nucl. Soc. 21, 463 (1975).

) (8 R.W. Benjamin, DP-1324 (1973)L SR , .

(9) T.M. Snyder, CONF-660303, Book 2, 1025 (1966).

. YiftahS . Cane(10 M d ) an r , paper presente r IAEfo d A TND Advisory Group Meeting (Nov. 1975).

(11) B. Hinkelmann, KFK-1186 (1970).

(12) M. Caner and S. Yiftah, INDC (ISL)-2/L, IA-1301 (revised Jan. 1975).

(13) M. Caner and S. Yiftah, IA-1243 (1972), IA-1275 (1973) and IA-1276 (1973).

(14) M. Caner, S. Yiftah, B. Shatz and R. Meyer, Proceedings, International Symposium on Physics of Fast Reactors, Tokyo, Vol. II, pp. 683 - 702 (1973).

(15) R.J. Howerton, Livermore, U.S.A., private communication.

(16) R.W. Benjamin, Savannah, U.S.A., private communication.

(17) H. Tellier, Saclay, France, private communication.

(18) R.W. Benjamin . Vandervelde0 V , , T.C. Gorre d F.Jan l . McCrosson, DP-MS-74-61, presented at the Conference on Nuclear Cross Sections and Technology, Washington D.C. (March 1975).

. (19YiftahS ) , (also: D. . IlberYiftah)S d an g , "Neutron Nuclear data evaluation", IAEA-153 and IAEA Technical Report 6 (1973)Serie14 . No s.

. Yiftah(20S ) . Gur . GitterY L ,. Sege ,d M an v , Proceedings, International Symposiu Physicn mo f Faso s t Reactors, Tokyo, Vol. Ill, pp. 1479 - 1490 (1973).

. GitterL . Segevd (21M an . ),r Yiftah S ,Nuclea Gu . Y , r Sciencd an e Engineering, 55, pp. 103 - 104 (1974).

. Yiftah S . Cane (22M d )an r , Analysi d Comparisoan s f Plutonium-23o n 8 Nuclear Data, accepted for publication in Nuclear Scienc Engineerind an e g (1975).

189 (23) H.C. Clairborne, Neutron-Induced Transmutatio f High-leveo n l Radioactive Wastes, ORNL-TM-3964 (Dec. 1972).

. RamanS (24) , C.W. Nestor, Jr.d W.Tan , . Dabbse Studth A , f o y 23- 3U Th Reacto23 2burnea s Actinidr a rfo e Wastes, presente Conference th t a d Nuclean eo r Cross Sections and Technology, Washington D.C. (March 1975).

Table VI.

Cf-252 u spontaneous fission

Accuracies requested

U.S.A. 0.25% primary standard

Canada 0.5% to resolve discrepancies

France 0.3% to resolve discrepancies

U.S.S.R. 0.1% n n kefi d i 1.6 an % f 1 r fo breeding rati f faso t breeders

TablI VI e

Cf-252: energy spectrum of spontaneous fission neutrons Accuracies requested______

U.S.A. % 5 , 1%

U.K. 2%

France 2%

190 H HI

ll 1 C N 0 F Nl ,« i i u III Al SI P S Cl Ar ii V* it II IS ii ft Cl Sc II V Cl Ha Co Nl Cy ZB Gl Cl Sc Bl Kr ii 11 ii H il 14 ,," it li 1! it H )S fib Sr 1 Nb Mo Te Ru Rb Pd »r U III Sfl Sb Tl XI 11 n 11 41* 41 ii 4) 44 is it

Cl Ba Ii HI Tl W ll Ir PI Al Hi Tl Pb Bl Po At On SI H ii it 14 IS 1,°' n u 11 II * li ii 1! |i IS n Fi Rl Ac Oio) (112) (115) (in) (lit) n u n . — A

LANTHANIDES Cl Nd Pn Sn Gd Tb Ho Tin Vb U

ACTINIDES Tb Pa Pti Am Cm Bk Fm Md Nt

Pig .1 Conventional for Periodif mo c Table showing predicted locations of new elements. (1)

Appendix. Transactinium Nuclear Concentratio n Speni n t Fuels from

Thermal and Fast Reactors

As an example and illustration of the concentration of transac- tinium nuclide n speni s t fuels from therma fasd an lt reactorse w , reproduce below part of the results of a calculation (using the Oak

Ridge ORIGEN code e ORNL-4628se , , 1973) performe n Karlsruhi d e

(KFK-1945 , e purpos1974)th r f assistinfo o e, e developmenth n gi t and desig a larg f o ne fuel reprocessing plant r wast fo s wela ,s ea l disposal procedures.

Needless to emphasize these and similar calculations and pre- dictions e depenreliabilitth n o d accuracd e ycrosan th f syo sections that serve as input, where significant gaps exist.

The calculations were done for 1 GWe (= 1000 MWe) power reactors of the PWR type, with and without plutonium recycle, and also for a 1 GWe sodium-cooled fast breeder,

Sdme details about the reactors follow the table.

191 17.3

559^ J236pu! 238Pu 164*1 L —I _ J__ 22h\50% 0 2.1 d 2200

172 237Np 238Np 650

Cross Sections Indicated e Currenar t Best Estimates Numbers Above Arrows are Thermal Cross Sections; Those Below 690 th e r ResonancArrowfo e ar s e I860 Integrals. 1 r "^C-n 243fm —:- H 150 ? i U J

\ m 832 24lAm 242Am -j243Am; 1538 o v L__J

<300 I6h\l7% EC

J242PUJ ___ _L _ -) cr 2200 c Neutron Capture

I63Jd/d a !6\83%/9- (Half-Life and 7 \ Branching Ratios Indicated)

Appreciable Fission

238e FIGURPTh u . ProductioE2 n Chain) s(8

192 2830. 2200^

S IS 155 ilOJ?>,2 «ME, 264E, 7308 OS N

2018 - 14 342 1.3 60(?) 2<»4Cm 24SCm Z48Cm "7Cm 248Cm 606 102 120 800(?)

I0.lh\\26m J°L Neutron Capture Ic

\4.98h lO.IIA g" Deca d Half-Lifan y e

00 EjM»pJ cr," 1275 L..J ~j—— Appreciable Fission Cross Section e Currenar s t Best Estimates Numbers above arrows are thermal cross sections; those belor resonance arrowfo th we ar s e integrals.

FIGURE 3. The 252Cf Production Chain (8)

1 GW= 100( e 0 MWe) Reactors

LWR PWR equilibrium fuel cycle 3.3% enriched uranium annual fuel replacement 26.Ot U/GW a (loae d factor 0,8) refueling fraction 1/3 of core burnup 34000 MWD/t heavy metaspecifia t a l c powef o r 29,5 m

LWR equilibrium fuel cycle 4.5% enriched uranium burnup 45300 MWD/t HM

LWR first and second plutonium recycle, ^19% of fissile charge plutonium, burnup 34000 MWD/M H t

193 FBR oxide fueled sodium cooled fast breeder equilibrium fuel cycle annual fuel replacement 34.4 t HM/GWe a (load factor 0,8) burnup of core 70 000 MWD/t heavy , averaged burnup of core and blanket 34000 MWD/t HM

Actinide Nuclide Concentratio Spenn ni t Fuel Day0 15 ss after Reactor Discharge (Grams/) HM T

LWR LWR FBR Pu- re cycle Half -life 34 GWD/T 45 GWD/T 1 recycle 2 recycle core+blanket Nuclide Tl/2 34 GWD/T

U-234 247000 Y 119 389 105 108 0.9 U-235 7.10E+8 Y 7560 8210 6890 7070 2330 U-236 2.39E+7 Y 4580 6450 3600 3580 330 U-238 4.51E+9 Y 942000 927000 941000 942000 864000

Np-237 2.13E+6 Y 500 769 376 368 271 Pu-238 88.Y 9 180 304 237 260 30 Pu-239 24400 Y 5270 5260 5360 5360 75800 Pu-240 6760 Y 2200 2310 2610 2650 22100 Pu-241 14.6 Y 1050 1160 1440 1490 2210 Pu-242 38000Y 0 380 488 966 1230 627 Am-241 433 Y 47.2 51.5 79.9 85,5 220 Am-242M 151 Y 1.0 1.1 2,2 2.4 2,5 Am-243 7650 Y 105 155 462 686 36.8 Cm- 2 42 163 D 5,8 4.7 14,7 16.3 2.7 Cm- 2 43 32.0 Y 0,1 0.1 0.3 0.4 0.2 Cm- 2 44 18,1 Y 34.4 60.0 273 456 1.9 Cm- 2 45 8260 Y 2.3 4,4 24.2 42.0 0.04 Cm- 2 46 4710 Y 0.3 0,6 4.8 8.8

Total Trans- 9776 10568 11850 12655 101302 uranium elements

194