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Title THE AMALGAMATION BEHAVIOR OF HEAVY ELEMENTS 4. THE TRACER CHEMISTRY OF DIVALENT MENDELEVIUM

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Author Maly, Jaromir.

Publication Date 1968

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UNIVERSITY OF CALIFORNIA.

La~rence Radiation Laboratory Berkeley California

AEC Contract No. W-7405-eng-48

THE AMALGAMATION BEHAVIOR OF HEAVY ELEMENTS

4 . THE TRA.CER CHEMISTRY OF DIVALENT MENDELEVIUM , , Jaromir Maly

January 1968 -iii- UCRL-18046

THE AMALGAMATION BEHAVIOR OF HEAVY ELEMENTS.

4. THE TRACER CHEMISTRY OF DIVALENT MENDELEVIUM* . ,t Jaromir Maly

Lawrence Radiation Laboratory . University of California • Berkeley~ California

January 1968

ABSTRACT

In this paper it is shown that the extraction of medelevium into sodium

amalgam from sodium acetate solutions results in about a ten fold enrichment

relative to the lighter actinides (fu, Am, Cm, Bk).

Separation of Md from the heavler actinides may be accomplished by either

of two methods: 1) an amalgam containing Md, Fm, Es, and Cf can be decomposed

in cold concentrated HCI and then the Md may be coprecipitated with EuCl with 2 . . one order of .magnitude enri'chmentfrom Fm; 2) Md can be separated by electrol-

ysis in acetate or citrate-acetate solution on an electrode of mercury amalga-

mated with sodium. In the lanthanide series method 2) is used to separate Eu

or Sm from the other rare earths. The sequence of electrodeposition of actinides

in acetate-citrate solution is Md > Fm >Es > Cf.

These separation methods probably depend on the formation of stable 2+ '. . 3+ 2+ Md . The potential of the Md + e-7 Md couple was estimated by a series

of reductions, using YbC1 , Zn, EuC1 , CrCI , VC1 , and TiCI , all in 2 !i HCI. 2 2 2 2 3 2 All except TiC1 appear to reduce Md3 + to Md +, which can then be coprecipi tated 3 with EuS0 or BaS04; Md ,thereby enriched 10";30 X in the precepitate, relative 4 is t.o the daughter isotope 256m in solution. -1- UCRL-18046

INTRODUCTION

A previous communication(l) reported preliminary results concerning the

possible separation of Md from higher actinides by extraction into sodium ,. amalgam from sodium acetate solutions, or by an electrolytic one step separation of Md and Fm from Es. This(l) and a subsequent p~blication(2) reported the 2 first experimental evidence of the Md + state, an oxidation state which now

appears to exist for other heavy actinides as well. This paper presents a more 2+ detailed study of Md

Because of the relatively short half life of the25~s target used for

Md production (T / 20 days for 253Es) experiments were limited to a period l 2 = of about 1.5 months. Some experiments could not be repeated more than twice,

and consequently the results are of low statistical accuracy. The present

experiments on Md and other heavier actinides were done in an attempt to repeat

the more interesting experiments on electrolysis, extraction and reduction of

Eu and Sm carried out earlier by a. nWliber of workers. (3-10) -2-.. UCRL-18046

EXPERIMENTAL PROCEDURE

Isotopes of Md, Fm, and Es Produced by Irradiation , :1'

256Md , produced by irradiation with ~46 MeV He ions of an einsteinium . 2 target, consisting of ~ 5 ~g 253Es mounted on 4 ~g/cm Be foil was used for the 4 .. work reported here. . The Estarget contained ~ 1% of 25 Es and 255Es , the latter

being in equilibrium with 255Fm . . . 2 Irradiation for ~ 30 min with a beam current of 50 - 100 ~A!cm (10 to

20 ~A. through the target) yielded approximately 105 atoms of 256Md (and also 2 some 25L,li'm 25 Fm , 253Fm, 254Fm, 255Fm, and 256 Fm isotopes) which were collected

on a Be catcher foil, along with about 105 to 107 ad/m of 253Es , knocked out

from the target. The catcher foil was dissoived in 6 !'i HCl, containing ~ 500 ~g

l8.3+. This solution was treated with an excess of KOH to form La(OH)3 which

. . co-precepitated Md, Fm, and Es. Thel8.(OH)3 preCipitate, washed with 6 !'i KOH

and water, was usually dissolved in 200 f... of 2 !'iHCl, to form a IIstock Md"

solution. 4 The isotopes 252Md , 253Md , 25 Md which also were produced during

irradiation by (He,xn) reactions, could nbtbe 'detected. They are short lived

and decayed by K-capture totheii' Fm isotope-s. A few-7 .3~--MeV a-particles were

observed in t,he a spectrum due to 255Md (T / = 30 min). However this isotope l 2 was observed mainly after K-capture as 255Fm • A typical a-spectrum of "stock

Md" solution is shown in figure 1. A typical decay curve of 256Md , measured by

spontane~us fission of the 256Fm daughter isotope is shown in figure 2. -3- UCRL-18046

Radioactive Tracers

8 4 The tracer isotopes 23 U (in the U + state), 237Np (as NP4+) , 239pu 4+ 9 2 2 4 (Pu ), 241Axn, 244Cm , 24 Bk, 25 Cf, 253Es , 15 Eu, a~d 15 iEu (all 3+) were used in

. ~ 0.5 M HCl solution . " 2 4 25 Fm, 255Fm, and 25 Fm were used for measurement of the yield of Fnl 2 in chemical operations. In the case of 25 Fm its yield was corr~cted for the

growth of 255Fm from 255Es (measured 40 days after bombardment and compared

with the original 255Es present in the target) and for growth from 255Md (de­

termined from the amount of 255Md a s measured by it 1 s 7.34 ex energy and 30 min

11 half life). A known amount of the 11 stock Md solution wa s used for the chemical.

separation procedures (extraction, electrolysis, reduction, and coprecipitation),

and at the end of a particular procedure a part of each separate fraction was

electroplated and then counted by ex pulse analysis as described in references

11 and 1. The amount of 256Fmactivity was determined for each fraction either

by measuring the decay curve for spontaneous fission along with its ex spectrum,

or by utilizing a separate ex chamber and a surface barrier Si-A.u detector

employing a discrimiriatorforSF counts. At the same time SF and ex decay curves

were measured for a known amount of the stock solution in order to calculate

the yield of separated isotoPes in each fraction.

Chemicals

Chemicals used· were of reagent grade . The sodium amalgam wa s prepared jo' by dissolving freshly cut sodium metal in hot mercury. -4- UCRL-18046

Calculation of Md Yield

A.) Yield from decay curves. c The growth and decay curve of the SF activity (figure 2) is described

by the formula:

where (1)

The time t is measured from the end of bombardment, when Fm andMd are Fmo

and Mdo respectively. Because ~Md > ~Fm,for large values of t the curve in figure 2 becomes a fermium decay curve described by:

(2)

The yield of Md was calculated from the difference between the growth

curve for Fm described by equation (1) and the decay curve [equation (2)],

extrapolated to the time of separation.· For this difference:

t -'7m p 6 Fm(t ) = Fm( t ) - [(Fm + R -dMd ) e se ] sep sep 0 -M 0 ,

= R_ Md e -~tsep ~Md 0

6 Fm(t ) represents the difference between total fermium after decay of Md, sep and fermium before Md decay. Hence the difference may be used to calculate the

yield of Md. -5- UCRL-18046

6 5 B) Calculation of yield from the ratio SF of 25 Fm :a activity of 2 3Es

In the case of electrolysis, 'When the SF activity 'Was too lo'W to give

a good gro'Wth curve theactivi ty ratio SF /a 253Es 'Was follo'Wed for 3 to 6 hours,

•"' after 'Waiting more than 15 hours (t long t ) after the end of the bombardment = L 6 6 'When essentially all 25 present at t ,had decayed to 25 . From this . Md sep Fm ratio 9f SF/a 253Es in the original solution and in the separated fraction and

'With the aid of 253Es yield, the yield of SF in the fraction (ojoSF(t )) 'Was L

calculated. For the calculation of the yield of Md separated at t sep' 'We used the formula:

6 5 ojo SF(t) = 0j025 Fm (t. ) ~ + ojo 2 6Md (t ) 1 (4) L' sep A+l sep A+l

1 ~dMd(tse) 'Where A=. Fm{t } . , sep

6 255 and for 0j025 Fm (t ) we used the yield 0j0 Fm(t ), measured in a given frac- s~. s~ . tion and in the unseparated mixture •. The value of the factor A is read from

figure 2, a standard decay curve for the unseparated mixture, at t • -~t sep In the above equations, ~dMdo e is equal to that part of the SF 6 6 activity of 25 contributed by the of 25 at t ' 'While 256Fm(tsep) Fm dec~y Md sep in (4) represents that part coming from Fm present in the fraction at t l/A. sep is the ratio of SF activity fr~m Fm produced by mendeleviQ~ decay to Fm produced

directly. A/A+l is the fraction of SF activity from Fm produced directly. Multi­

plication by 100 gives the ojo of total SF activity originating from this source.

Measurement of a activity from. 253Es permitted a check on the yield of

total a's and consequently of total SF's through the chemical procedure. -6- UCRL-18046

Extraction Procedure

The extraction experiments usually ~ere carried out from a mixture of

20 A. of the "stock Md" solution in 0.15 ~ HC1, 25 A. of tracers in 1 ~ HC1, 9 A. 3 of 1 !1' HCl containing 120JJ.g of Sm3+ and 150 JJ.g each of Eu3+ and Yb +, 150 A. of

7 ~ sodium acetate, 5 A. of 8 !i ammonium acetate, and selected amounts of HC1, as shown later in table 1.

The extractions ~ere performed in a .3-:--llll cone using 250 'f... of sodium amalgam, containing ~ 3.5 milliequivalents Na/ml. The actinide 'elements ~ere back-extracted from part of the amalgam ~ith 6 ~ HC1, the extract neutralized by NH 0H, and then electroplated ona Pt disc.' Details of the extraction pro­ 4 cedure are described in reference (11) ..

~eremaining portion of the amalgam,after ~ashing ~ith H 0, was de­ 2 composed by ice cold concentrated HC1; NaCl crystals togetherw~thEuC12 were centrifuged out, washed with concentrated HC1, dis,solved in 1 ml of H 0 and 2 an aliquot ~as electroplated on a platinum plate, after neutralization with

NH40H.

The combined HCl supernatants were diluted to 2 ml. A known fraction

'of this solution was neutralized and electroplated as before.

Electrolytic Procedure '-.

The compositions of the solutions used in electrolysis were similar to those used foramalgaril extractions: 150 f... "stock Md"in 1 ~ HC1, (containing

~ 200 JJ.g La3+) 600 f... of 7 ~ sodi~ acetate, 20 f... of 8 ~ ammonium acetate, and

100 f... of 0.5 ~HCl in the first experiment; and 200 f... of "stock Md" in 3 ~ HC1,

25 f... of 0.5 ~ sodium citrate,300 f... of 7 ~ sodium acetate, and 50 f... of' 0.5 ~ HCl -77 UCRL-18046

in the second. In the first experiment 110 "- of tracer solution in 0.5 ~ HC1, 8 containing ~. ~ mg 23 U was also present.

11 The electrolyses were performed in the open air using 900 ,,-. and 300 "-

of pure mercury in the first and second experiments, respectively. The anode •.. consisted of a plat:i,.num spiral, held. at the surface of the .electrolyte . The

Md-rich fraction from electrolysis was subsequently used for experiments on

the reduction of Md3+ to Md2+.

The electrolyses were carried out for 35 min, with periodic inter-

ruption at 5 min intervals for sampling the mercury phase. Following any 5-min

period of electrolysis, the current was stopped,' and after 1 min of mixing of

both phases, 5 "-of mercury were withdrawn by pipeting. This sample was washed

thre~ times with water, transferred to a platinium disc, the mercury driven off

by heating, and the residue counted for Md and Es as in the extraction experiments.

Reduction Procedure

tl The Md tlstock solutiori was reduc~d by adding 4-:5 mg of YbC1 or EuC1 , 2 2

or else with amalgamated zinc in the presence of ~ 5 mgEuC1 . In other experi­ 3 I 2 2 I ments solutions of Cr +, V + and Ti3+ were prepared by reduction with amalgamated

zinc. In atypical experimeIlt, the reducing solution was prepared by adding a

0.1 Msolutionof the oxidized species in 2 ~ HCl to ~ 0.5 gm of amalgamated

zinc (20 mesh), contained in a l-ml cone. The solution was heated and repeatedly 2+ mixed by pipeting for 5 min. The concentration of HCl after reduction to Cr , ~+, or Ti3+ was about· 1 ~, because of the Zn dissolution during reduction. One ml of this freshly prepared reducing solutiQnwasadded to a 2 ml cone tl 3+ . 2+ containing 50 A; of tlstock Md , ~ 6 mg Eu ,and 300 ~g of Ba . in 100 "-

of 0.5 ~ HCl. After 1 to 2 min of reduction, BaS0 was precipitated by the 4 -10- UCRL~18046

For a comparison with other data reported in the literature, we recal- '()

culatedthe data of figure 4 to obtain the "amount left in solution," shown in

figure 6. After finishing the second electrolys is we replaced the mere ury phase

by 300 A. of freshHg and proceeded in the electrolysis of 253Es and 255Fm with 2 30 rnA/cm current density,. with results shown in figure 7. Both figures 6 and .... (13 14) 7 show, in agreement with the literattire ' an approximately linear relation.

I ., . between these qua,ntities. One can read from these curves the "periods of amal­ I gamation" introduced by Boussieres et al. (13) The results are ~. 100 rnA min for

Md, from figure 6 and ~ 300 rnA min for Fm and ~ 800 rnA min for Es from figure

7. The c,urves for 256Md in figure 6 and 255Fm in figure 7 show deviations

from a straight line (dropping faster when more charge is passed, as observed

by Onstott in the case of rare earths electrolyses. (8)

2 Potential of the Md3+ - Md + Couple

Although a correlation between the amount of extraction into sodiUm

amalgam and the formation of a chemically stable +2 state has been established

for the 4f elements, (3,15) a simil~r correlation has not been demonstrated for

the 5f series.

'J;'he expected analogy betweenTm and Md led Seaborg (16) in 1949 to pre-

dict that Md might have a +2 state.

Accordingly, we sought direct evidence for a dipositive state of men-

deleviQ~, and have attempted to establish rough limits for the potential of . 3+ 2+ the Md + e = Md couple~ To this end, various reducing agents were added

to the "stock Md" solution, and BaS0 or EuS04 was precipitated from the mix­ 4 6 ture. The distribution of 253Es , 256Fm and 25 Md activities between the pre-

eipitate and supernatant was then determineq. -11- UCRL-18046

Typical decay curves of the original solution and the EuS04 or BaS04

fractions, are shown in figure 8 (for reduction by amalgamated zinc - in the 2 2 presence of Eu +), figure 9 (reduction with Cr +) , figure 10 (reduction with 2 V +) ,and figure 11 (attempt at reduction with Ti3+). The curves in figures

8, 9, 10 show good evidence of growth of SF activity from 256Md separated in

the EuS0 or BaS04 fractions. For the case of Ti3+ only slight growth of 256Fm 4 was observed relative to the original solution, which indicated incomplete 2 reduction of Md3 + to Md + by Ti3+.

The reduction data are collected in table 2. The enrichment factor

of Md in the EuS0 or BaS04 fraction [defined as the ratio 4

-MRdMd( t sep ) ppt fraction Fm(t ) . sep

~dMd(tsep) original solution] Fm(t ) sep

2+ 2+ .2+ in all reduction runs with Zn, Eu ,Cr ,and y-.- was.between 10 and 90, as :;;;hown. 2 The yield of Md + coprecipitated with BaS04 was from 50-100%, but with EuS0 4

the yield was only ~ 5-10% when theEuS0 yield was also 5~10%. The reduction 4

with YbC1 gave the same result as with EuC1 , with an enrichment factor ~ 20. 2 2 , 3+ . . 2+ . 2+ 2+ 2+ These results show that Md . was reduced to Md by Yb ,Zn, Eu ,Cr and

y2+, but with Ti3+ the reduction was low. Since partial reduction occurred 2 ,.; with T)+ (EO == - 0.09y(1'7\n LM RC1) the Ma?+ + e---7 Md + reduction poten-

tial allparently is about -O.lV. -12- UCRL-18046

CONCLUSION '. The results presented in table 1 indicate that Md is extracted by sodiu.rn amalgam somewhat more readily than is einsteiniu.rn, and on comparison with results presented previously, (1) it appears thatMd is extracted more 2 2 readily than californiu.rn. This suggests that Md + is more stable than Cf + or 2+ E s • Additional data in table 1 show that in the separation of EuC12 from SmC1 , by treating these amalgams with ice cold concentrated HCl all of the Md 2 is carried by the solid EuC1 fraction. This suggests ,the existence of a 2 solid, slightly soluble MdC1 (in'conc. HC1), isostructural with EuC1 . 2 2 Figures 4 and 5 demonstrate'a very substantial separation of Md from

Es and Fm by electrolysis. The maximum separation observed was 0.8% Es:4% Fm:

90% Md by electrodeposition in merdury during the first electrolysis (figure 4) .

The maximum ratio of spontaneous fission activity due to 256Fm , to a activity of 253Es and 255Fm was reached after passage of ~ 9 Cof electric 6 charge.· The enrichment of 25 Fmin the mercury phase by a factor ~ 30 is due 6 to preferential electrodeposition of 25 Md on the cathode, while Es and also

Fm remain mostly in solution. This result is similar to the well-known electro..,.. lytic separation of Eu and 8m from other rare earths on a lithium-amalgamated cathode. (8,9,10) The observed large separation of Es from Md by electrolysis suggests that a substantial difference exists in the potentials of their 3+ -

2+ couples. To prove this difference, the reduction experiments sUIll.rnarized in .. . 3+ 2+ table 2 were carried out. These data ~nd~cate that Md. can be reduced to Md and then precipitated with EuS04 or BaS04, usually with an enrichment factor > 10 (in comparison to Es) with any of the following reducing agents: YbC1 , Zn 2 3+ 2+ 2+2+ (Jones' Reductor in the presence of Eu ), Eu ,Cr ,or V in 2 M in HCl solution. -13- UCRL-18046

2 I~\ follows that the reduction potential for the Es3+ - Es + couple 2 must be more negative than for the Md3+ - Md + couple by ~ 1 V or more. 2 The oxidation potential of Md3+ ~ Md + couple is close to the oxidation 3+ 4+ potential of Ti ~ Ti in 1 .~ HC1, about -0.1 V.

The results suggest that the +2 state of mendelevium is more stable

than the dipositive state of ytterbium, and eVen of europium. The substantially

greater ease of reduction of Md as compared to Es affords a basis for a rapid

and efficient separation of the elements as shown by the reduction experiments. 3+ . The Md can be separately reduced, for instance by zinc using a Jones 1 2 Reductor, to Md +, while Es and Fm remain in the 3+ state.

~/ -14- UCRL-18o~·6

ACKNOWLEDGMENTS • The author is grateful to Dr. A. Ghiorso for conducting the bombard- ments and to Dr. K. Hulet of the Lawrence Radiation Laboratory, Livermore, whose einsteinium samples served as target material for the preparation of the men- deleviu.TJl used in these experiments. The author would like to express his deep gyatitude to Professor B. B.Cunninghamfor his continuous support, criticism and valuable assistance during this work. To Dr. N. Edelstein the author is indebted for valuable editing assistance. Appreciation is expressed also to the operating staff of the HILAC. Finally, I would like to express my grati- tude to IAEA, Vienna, for financial support of this work in the form of an

IAEA research grant at the Lawrence Radiation Laboratory. -15- UCRL-180l.j·6

FOOTNOTES AND REFERENCES

-)(- This -work performed under the auspices of the U. S. Atomic Energy

Commission. t . Permanent address: The Nuclear Research Institute of Czechoslovak

v \,I Academy of Sciences, Rez u Prahy, Czechoslovakia ..

(1) J. Maly, B. B. Cunningham, Inorg.Nucl. Chem. Letters 2, 445 (1967).

(2) E. K. Hulet, R. W. Lougheed,J . D. Brady, R. E. Stone, M. S . Coops,

Science 158, 486 (1967).

(3) J. K. Marsh, J. Chem; Soc., 398 (1942).

(4) J. K. Marsh, J. Chem. Soc., 523 (1942).

(5) J. K. Marsh, J. Chem. Soc., 8 (1943).

(6) J. K. Marsh, J. Chern. Soc., 531 (1943).

(7) E.1. Onstott, J. A1'Jl. Chern. Soc., 77,2129 (1955).

(8 ) E. 1. Onstbtt~ .. J. Am. Chern. Soc. 78,2070 (1956).

(9) E.1. Onstott, J. Am. Chem. Soc., 81,4451 (1959).

(10) J. K. Marsh, Syn. 2., 22 (1957). -, (11) J. Maly, Inorg. Nucl. Chern. tetters 2, 373 (1967) •

. (12) Jaromir Maly, University of California La-wrence Radiation

Laboratory Report UCRL-17987.

(13) F. David and G. Bouissieres, Bull. Soc. Chim. France, 1001 (1965).

(14) F. David and G. Bouissi~res, Inorg. Nucl. Chem. Letters, in press. ," (15) . W. Noddack and A. Brukl:;Ange-w. Chern. 50, 20, 302 (1937).

(16) G. T. Seaborg, J. J. Katz, and W. M.Manning, The TransuraJiium

Elements, Part II,National Nuclear Energy Series, Vol. 14B,

Paper 21.1, Mc Grm/-Hill Book Company, Inc., Ne-w York, 1949. -16- UCRL-1So46

(17) J. J. Lingane, ElectroanalyticalChemistry, Interscience Publishers, r;

Inc., New York, Second Edition, 1964. " (lS) A. Ghiorso, private communication. ':'17- UCRL-18046

~. SODIUM AMALGAM EXTRACTION OF ACTINIDES AND SEPARATION WITR EuC1 Table 1. 2 - .. SmC1 BY CONC RCl . . 3 ~' ,. .. .. 237 . 239 241A 246 252 253 255 256 Element Np pu m em Cf . Es Fm Md .." A) 15 A ~ RCl added before extraction:

% extracted 4.0 5·3 5·65· 6.8 58.1 89 ""100 ""95 : !, intosodilun

.- ~ amalgam

% in 0·33 0·37 0.25 0.15 1.5 1.4 3·1 ~5 EuC12 (s) 3+ % inSm 3:6 4.9 5·9 6.6 56.6 87.5 97 ""10 fraction

:8) 75 A. l!i RCl added before extraction:

% extracted 18.2 19·3 20.6 12.0 96.2 ""100 ""100 ""100 into sodi u..rn amalgam

%·.in 1.0 0·95 4.7 0.65 5.6 2.6 4.4 97 EuC12(s) 3 % in Sm + .17·2 18.3 15·9 11.3 90·5 97.4 95.6 3 fraction

. i }.I '. ) . -18- UCRL-18046

Table 2. RESULTS OF REDUCTION OF Md " Reducing Precipi- Reduction Corresponding Experi- ~dMd(\e ) Enriching Ion tate Potential Reaction ment factor in Fm(t ) " (volts) No. sep precipi- tate of of input reduc- tion 2+ . Zn + Eu?+ EuS04 -0.763 Zn' + 2e -+ Zn 1. 0.6 19·0 31. 7 (Jones I Reductor) 2. 0.22 4.0 18.2

3· " 1~00 90.0 90.0

-0.43 0.21 5.25 25.0

2. 0.25 5.0 20.0

2.00 35.0 17·5

2+ Cr -0.41 0.15 1.54 10·3

2. 0.086 3.0 34.8

3+ _2+ ~+ -0.255 V +e-+V 0.107 2.0 18.6

2. 0.67 9.0 13.4

3. 0.28 5.7 20.4

3 Ti + BaS04 -0.09 TiOC1+ + 2H+ 1. 0.26 0.8 3·1 + 3Cl- +e -+ T1C1 +·H O 2. 0.24 1.15 4.8 4 2 \,i 11- -19- UCRL-1S046

FIGURE CAPTIONS

Fig. 1- Typical ex pulse height analysis spectra of "stock Md" solution. (", 256 Fig. 2. Typical decay curves of Md measured by the spontaneous fission of 6 J' the 25 Fm daughter isotope.(lS) Fig. 3. Spontaneous fission activity present in the EuC1 fraction (precipitate) 2 and 'the SmC1 fraction (Bupernatant) . The SF data for the EuC1 fract ion 3 2 represented by ••• ; the data for the SmC1 fraction by AU, the SmC1 data 3 3 corrected for background by 000. A small amount of the "stock Md" solution

is represented by~~~.

Fig. 4. Percentage of actinide tracers electrodeposited in mercury as a function 2 of time and passed charge. Current density used in this experiment was 5 rnA/cm .

, Fig. 5. Percentage of actinide tracers electrodeposited in mercury as a fun,ction

of time and passed charge. Current density used in this experiment was 2 10 rnA/cm .

Fig. 6. Percentage of actinide tracers left in solution as a ,function of time ~', 2 and passed charge (5rnA/cm ) . Fig. 7· Percentage of actinide tracers left in solution as a function of time 2 and passed charge. Current density used in this experiment was 30 rnA/cm .

Fig. S. Decay curves for the original solution·and the EuS04 fraction o. The

reducing agent used was amalgamated zinc.

Fig. Decay curves for the original solution 0 and the BaS0 fraction \7, 9. 4 o. 2+ The reducing agent used was Cr .

Fig. 10. Decay curves for the original solution 0 and the BaS0 fraction ,~, 4 The reducing agent used was ~+.

Fig. 11. Decay curves for the original solution ~ and the BaS04 fraction 0.

The reducing agent used was Ti3+. -20- UCRL ....18046

280~~~----r------~---~------~------r----~------.----~

253Es 240 6.63 MeV

.' :.~'. 200 7.20 MeV .-c:: E 160 0 ,."

'"VI .... 120 c:: ::::J 0 .~' u

60 70 80 90 100 110 120 130 No. of channels

XBL685-2665

Fig. 1 -21- UCRL-18046

(""t, 5 10

J' c c E E 0 4 0 10 r0 ...... (/) (/) +- +- c C ::J ::J 0 0 U ...... U - 3 c 10 c 0 0 (/) (/) (/) (/)

(/) - -(/) /' ::J ::J 0 0 Q) 2 Q) c 10 c 0 0 +- +- c c 0 a. a.0 CJ) • • CJ)

10 0 200 400 600 800 1000 1200 1400 Minutes

XBL685-2659

\, /;

Fig. 2 -22- UCRL-18046

.-c: E lO ...... If) +- c: ::l 0 -0 c: 0 10 If) If)

-If) ::l 0 T = 2.8 hr Q) 112 c: 0 +- c: 0 0. en

t sep (extraction) 0.1 10 12 14 16 18 20 22 24 2 4 6 8 10 12 14 16 18 20 June 1,1967 June 2 Hours

XBL6B5-2663

Fig. 3 -23- UCRL-18046

256 2 Md 10 .'"

~ r SF 0~ 10 ~ J: .-c:: 255 Fm "0 Q) +- (/) 0 Co Q) "0 .. 0 ~ +- u 253 E S Q) W

10 20 30 40 50 60 min 50 100 150 200 250 300 mA min

XBL685-2666

Fig. 4 -24~ UCRL-18046

0~ 10 0' :I: .-c: "0 Q.) +- f/) 0 c.. Q.) "0 0 253 "- Es +- 0 u 0 0 0 Q.) 0 W

· ?[

0.1 o 5 10 15 20 25 30 min o 50100 150 200 250300 m Ami n

XBL685-2667

Fig. 5 'j , } ) -25- UCRL-18046

• • 253 255 Es Fm

SF

I o

,f, -'*" c: o +­ ::J o II) c:

+­ -Q) ...J

10 o 10 20 30 40 50 60 min o 50 100 150 200 250 300 mA min

XBL685-2668

; ,rj

Fig. 6 -26~ UCRL-18046

10

0~

.,'

:·,1 I C 0 +- ~ 0 (/) c:

+- " , -Q) ...J

0.1 ~ __~ __~~ __~ __~ ____L- __~ ______~ o 40 60 80 100 120 min o 1200 1800 2400 3000 3600 mA min

XSL685-2669

Fig. 7 -27-

... 2 ..c. 10 ...... (/) +-c ::) 0 (.) hr c 0 (/) Background (/) 10 • • • • •

-(/) , ::) I 0 , (l) I C I c +- Start of c It 0 I counti ng 0.. en B ackg round o 0 0 0

~ .. Tim e of E u S 04 precipitation

12 June 1, June 2 , June 3, 1967 Hours • XBL685-2660 t./

Fig. 8 -28- UCRL-18046

c E 0 2 ...... 10 fI) +- C :::J 0 -U C 0 fI) ....fI)

fI) CO :::J 0 CI). c 0 10 +- c 0 Q. (f)

.. 2 4 6 8 10 12 14 16 18 20 H OU r s

XBL6 85 - 2661

Fig. 9 "}·' -29- UCRL-18046

.-c E 0 2 ...... I 0 In +- C ::3 0 ()

c 0 In In

-In ::3 0 Q) c c I 0 i c -0 0- en

·t.: ~ ". ;

, ., .~ '~ ~,( '1., j 2 4 6 8 10 12 14 16 18 20

Hou rs • XBL685-2662

Fig. 10 -30- UCRL-18046

.-c E 0 2 ...... 10 , (/) +- C :J 0 U

C 0 (/)' (/)

-(/) :J 0 Q) c 0 10 +- tin c em 0 Q. (f)

tsep , o tsep 15.

6 10 12 14 16 18 20 .. Hours

XBL685-2664

Fig. 11 • This report was prepared as an account of Government l sponsored work. Neither the United States, nor the Com­ • mISSIon, nor any person acting on behalf of the Commission:

A. Makes any warranty or representation, expressed or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, appa­ ratus, method, or process disclosed in this report may not infringe privately owned rights; or

B. Assumes any liabilities with respect to the use of, or for damages resulting from the use of any infor­ mation, apparatus, method, or process disclosed in this report.

As used in the above, "person acting on behalf of the Commission" includes any employee or contractor of the Com­ mission, or employee of such contractor, to the extent that such employee or contractor of the Commission, or employee of such contractor prepares, disseminates, or provides access to, any information pursuant to his employment or contract with the Commission, or his employment with such contractor. • ~

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