ORN L-2857

SOLUBILITY OF ZIRCON IUM DIBUTYL PHOSPHATE

IN SOLVENT EXTRACT ION SOLUTIONS

We Davis, dro H. H. Carmichael

OAK RIDGE NATIONAL LABORATORY operated by

UNION CARBIDE CORPORATION for the

U. 5. ATOMIC E N E R G Y COMMlSSlON

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

DISCLAIMER

Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

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C o n t r a c t NO. w-7405-eng-26 . . . .

. . . . . . . . . CHEMICAL 'IXCHNOLOGY D I V I S I O N

. .

' c h e m i c a l D e v e l o p m e n t Section B

. ..

SOLUBILITY OF ZIRCONIUM DIBUTYL PHOSPHATE I N SOLVENT EXTRACTION SOLUTIONS

W . D a v i s JP. 8 . H. C a r m i c h a e l

DATE ISSUED

JAN 2 0 1960

OAK RIDGE NATIONAL LABORATORY Oak R i d g e , T e n n e s s e e

O p e r a t e d by UNION CARBIDE CORPORATION

f o r the U . S. ATOMIC ENERGY COMMISSXON

ABSTRACT

The solubility of zirconium dibutyl phosphate in aqueous uranyl nitrate and nitric acid solutions was found to vary from 0.35 to 159 mg of zirconium per liter, ,increasing with increasing uranium con- centration. 'The. solubility in 1.126 M TBP in Amsco 125-82 equilibrated with uranyl nitrate-nitric acid aqueous solutions was found to vary from 0'.33 to 3.55 '& of zirconium per liter. Particularly in the ex- tractant solutions, the solubility of zirconium as zirconium dibutyl phosphate is well above the zirconium content of even extensively burned natural uranium fuels under Purex process conditions.

The zirconium dibutyl phosphate studied was prepared by direct synthesis in aqueous solution and found to have a variable composi- tion. Precipitation from 2 M HN03 at 40°c yielded a product which had the approximate compositTon ~r (.OH) (If03 ) (DBP)~.

C OfiTENTS . . . . . . .

Page

1.0 Introduction

. ,

2.0 Experimental Results . .

2.1 Solubi l i ty Data

. 2.2 Behavior of Zirconium Dibutyl Phospkte

2:3 preparation and Composition of zirconium Dibutyl Phosphate 7.

3.0 Experimental Procedures

4.0 Process Applicat,ions

5.0 References

1.0 INTRODUCTION

The work described in . t h i s . report was performed t o determine some of the p r o p e r t i e s o f zirconium dibutyl phosphate i n Purex solutions and t o elucidate the ro le of dibutyl phosphoric acid (HDBP), a product of the de- gradation of t r ib .uty1 phosphate (TBP), i n the behavior of zirconium i n the solvent-extract ion of nuclear fuels . Dibu y l phosphoric acid, which i s formed by ac id deallrylationl o r radiolysis2 of TBP, has been sh0wn2,~ t o cause the extract ion of zirconium in to TBP-kerosene extractant solutions. Uranium represses t h i s extract ion very markedly, but ~ u l c e s ~ found a dis- t r ibu t ion coe'fficient, DC:, of zirconium from a 3.0 M HN03 solution in to 30% TBP-dodecane of 0.44, at 70°C, with no dibutyl pEosphoric acid i n i - t i a l l y present. Thus, dibutyl phosphoric acid i s not the only factor involved i n low decontamination of uranium and plutonium from zirconium.

The scope of t h i s report includes measurements of the so lubi l i ty of zirconium dibutyl phosphate, by use of Zr-95 t racer , i n aqueous and 30% TBP-Amsco solutions containing uranyl n i t r a t e and n i t r i c acid i n concen- t r a t i o n ranges spanning those found i n the Purex process. These measure- ments a re probably accurate t o a fac tor of about 3. In addition, q d i - t a t i v e observations on the behavior of so l id zirconium dibutyl phosphate i n k o n t a c t with these and other solutions are described.

All chemical and radiochemical analyses described i n t h i s report , . ' i . . were performed by members of the groups of W. R. Laing, 0. Menis, P. F. ' I , . .. . . .. .

~hohason, G. R.. Wilson, and E. I. Wyatt of the ORNL Analytical ~ h e d s t r y ~ i v ' s ion. 3 0

2.1 Solubi l i ty Data

Solid zirconium dibutyl phosphate, i n i t i a l l y containing 3.71 mcurie of Zr-95 per gram of zirconium, was agi tated with 16 aqueous solutions, of i n i t i a l composition 0-3.96 M HNOj and 0-490 g of uranium per l i t e r , and with 16 extractant so lu t ions prepared by contacting portions of 1.126 M TBP i n Amsco 125-82 with s i x successive portions of each of the aqueous solutions. This exhaustive contacting w a s performed t o provide extrac- t a t ' s o l u t i o n s in equilibrium with the corresponding "as-prepared" aqueous solutions.

Quant i t ies of zirconium dibutyl phosphate dissolved i n the aqueous solut ions varied from.0.22 t o 159 mg of zirconium per l i t e r ; correspond- ing quant i t ies dissolved i n the extractant . solutions varied from 0.33 t o 3.55 g of zirconium per l i t e r a able 1). Although there was excess so l id i n contact with a l l solutions a% the time of sampling, the changes i n z i r - conium co t e n t with agi ta t ion time noted i n Table 1, and the observations f: of off at t h a t several days t o a week, o r more, a re required t o achieve

Table 1. Zirconium Dibutyl Phosphate Dissolved i n Aqueous. and. 30%. TBP-Amsco solutionsa

Aqueous Phase 30% TBP-Amsco Phase a t Equilibrium I n i t i a l Comp. Agitation Z r Init ial . Comp. Agitation Z r

Smple , u, Time, Content, Sample H+, u, Time, Content, NG . M hr mg/liter No. M - M - hr g / l i t e r - M -

126 M' TBP i n Amsco before contacting with aqueous solutions. b ~ d d i t i d time s t a t i c &cept for occasional shaking.

so lu t ion sa tura t ion in similar studies, suggest t h a t not . a l l the values of zirconium content are t r u e s o l u b i l i t i e s .

The reasons f o r the slow r a t e of dissolut ion of zirconium dibutyl phosphate i n t h e aqueous and organic solutions used i n the present study are no t c l ea r . It was observed t h a t as much a s two days were required t o w e t t he so l id i n a few of the aqueous solutions. After such wetting, most of t he so l id formed a f ro th on the top of the aqueous solut ion and only a small quant i ty s e t t l e d on standing. However, a l l organic solu- t i o n s appeared t o wet the zirconium dibuty l phosphate within a few hours.

Increasing the uranium concentration c lear ly increased the so lub i l i t y of zirconium dibuty l phosphate i n the aqueous phase. This e f f e c t of uranium may p e r s i s t i n the organic phase t o a small extent, as suggested by the de- creased zirconium content i n samples 13-0, 14-0, 15-0, and 16-0, i n which no uranium was present, below t h a t i n a l l other organic samples, i n which uranium was present. It should be noted t h a t the TBP i n samples 1-0 through 8-0 was saturated with uranyl n i t r a t e and n i t r i c acid, primarily the former, and t h a t samples 9-0 through 12-0 were nearly saturated with uranyl n i t r a t e ; t$us, these solut ions were so nearly of t he same composition t h a t only small

e ;.V - changes I , : s i n zirconium dibuty l phosphate so lub i l i t y would be expected. ..::-. , . . . . .: ..,. ,, .. . . $ 2 Behavior of ZirconiumDibutyl: Phosphate . .>.. ,/' .,>. . .I.; ..,,, ; . Air-dried .zirconium dLbutyl phosphate was wetted and dispersed by the

.. i:. i:: .

T$P-Amico solut ions . When the compound.ys added t o the aqueous solutions, .:, .* - .., i6me ;of it.. was: wetted .,and sett led, . .but .the..b.ulk formed a f r o t h on top of. the. :. 12quid .

., . .

' Preliminary s tud ies showed the zirconium dibutyl phO.S~ha.te t o be soluble to ' the order of 2% i n methanol and s l i g h t l y soluble i n ethanol and carbon t e t r ach lo r ide a t 25'~. It was qui te soluble i n ethanol on warming but r e - crJ is ta l l ized as a . p&~,&%: , mass which stuck t o the glassware. A small amount of water added t o a hot methanol solut ion caused precipi ta t ion, on cooling, of a m t e r i a l similar t o the or ig ina l p rec ip i ta te . This, too, turned t o a pasty mass on standing 48 h r .

Zirconium dibuty l phosphate i s an e f f ec t ive c a r r i e r f o r niobium. Only 4%- of t he microscopic amount of niobium remained i n t he f i l t r a t e from the o r i g i n a l p rec ip i ta t ion , while 18.5% of the zirconium did not p rec ip i ta te . From the amount of c a r r i e r zirconium, the l o s s t o the f i l t r a t e , and the z i r - conium content of t he prec ip i ta te , a t heo re t i ca l yie ld of 14.5 g oras ca l - culated f o r the prec ip i ta t ion containing Zr-95. The l@ difference between t h i s and t h e ac tua l 13.0-g y ie ld can probably be explained by the zirconium ana lys i s being low. This sample did not dissolve i n perchlor ic-sulfur ic ac id but required t h e addi t ion of hydrofluoric acid . The -or ig ina l t r a c e r had a niobium/zirconium rad ioac t iv i ty r a t i o of 1.7. The f i l t e r e d solveqt solut ions had r a t i o s varying from 0.37 t o 106 with 14 of 46 samples having r a t i o s below 2.0, t h e value calculated f o r the so l id . Onlyztwo had r a t i o s above 10.

Two organic solutions contacted with 4 M HN03 became discolored on equi l ibrat ion with zirconium dibutyl phospha?e.

The so lub i l i t y of zirconium dibutyl phosphate has been reported by Moffat and Whitener4 as 0.0 and 3.6 g of zirconium per l i ter i n water and 3$ TBP i n Amsco, respectively. The values found i n the present work a r e 0.22 mg per l i t e r of water and 1.34 g per l i t e r of 30$ TBP i n Amsco. The value f o r the so lub i l i t y i n 3% TBP i n Amsco was obtained with an equ i l i - brat ion of more than 1 week.

Preparation and Composition of Zirconium- Dibutyl Phosphate

Four inact ive and one Zr-95 labeled samples of zirconium dibutyl phos- phate were made. The f i r s t precipi ta t ion, C-18-2, was performed by adding 1.3 m l of dibutyl phosphoric acid, HDBP, t o 100 ml of a hot, 60-7o0c, solu- t i o n adjusted t o 0.064 - M zirconium i n 3 M HNO . This sample was f i l t e r e d and dr ied under vacuum. The second prec ip i ta 2 ion, C-19-1, was performed by adding 100 m l of 13.7% solut ion of HDBP i n ethanol t o 100 ml of a hot, F165'~, 0 ~ 0 6 5 _M zirconium i n 3 M HNO . The prec ip i ta te was f i l t e r e d and dr ied under vacuum. The t h i r d p r e c 9 pi ta t ion, C-21-1, was performed by dropwise simultaneous addi t ion of equal volumes of 0.130 M NaDBP and 0.065 _M zirconium i n 3 M HNO3 t o 2 M RN03 solution. During t h i s gddit ion vigorous s t i r r i n g was usgd and the sku t ion -p rec ip i t a t e was heated t o 40'~. The prec ip i ta te was f i l t e r ed , then redispersed i n 200 m l of 2 M HNO and s t i r r e d

- a fo r 20 min, and f i n a l l y r e f i l t e r e d and dr ied under vacuum. Con i t i o n s of the fourth precipi ta t ion, C-27-1, were the same as those of the t h i r d ex- cept t h a t the solut ion was not heated.

The Zr-95 t r ace r used i n t h i s work was received as 10 mcur&es of Zr-95 and. 17. ~ , ~ & q . g . of Nb-95 i n 6.9 m l of oxalate solut ion. This solu- t i o n was d i l u t e d ' t o 47 m l , the oxalate destroyed by addi t ion of a small excess of potassium peraanganate solution, and the excess of the l a t t e r jus t destroyed with hydroxylaraine hydrochloride solut ion. Water and a stock solution of 5.89 M H+, 0.71 3 Zr, 0.35 M Na, and 8.20 M NOS were added t o the Zr-95 sol iz ion t o make 100 m l cof;taining 0.25 M-zr and 2.80 - M HN03 . This solution and 250 ml of 0.20 - M NaDBP wereadded drop- wise, with slow s t i r r i ng , t o 100 m l of 2 M HN03. The zirconium was added mch more rapidly than the NaDBP sorution, which was added over a period .of 30 min. After digest ing -for 30 min, t he prec ip i ta te was f i l t e r e d and washed with 100 m l of d i s t i l l e d water. The l i qu id was '

pulled out of the f i l t e r cake by vacuum f i l t r a t i o n and t h e so l id dr ied fo r .24 h r under a heat lamp. This material was labeled C-32-1.

Chemical and thermogravimetric analyses (Table 2 and Fig. 1 ) of the zirconium dibutyl phosphate preparatfczn.s indicate t h a t d i f f e r en t compounds were formed under the various conditions of precipi ta t ion, neglecting d i f - ferences i n the amounts of water and n i t r i c ac id of solvolysis. Thus, the atomic r a t i o P / z ~ , varying from 1 t o 3, indicates a d ibuty l phosphate' anion t o zirconium ra t ion r a t i o of 1 t o 3 since a l l phosphorus was added a s , t h e . hydrogen o r sodium dibutyl phosphate. Since the thermogravimetric weight loss a t 200°c, a temperature a t which, sorbed solvent was removed ( ~ i g . l ) ,

Table 2. Analyses of Zirconium Dibutyl

Phosphate Preparations

. Loss on Chemical. Analyses, Mole Ratios Heat in6

w t $ t o 200 C, Sample Z r P C NO3 P/Zr C/Zr N O ~ / Z ~ C/P wt $

'?Phis value should b e 14.3% on t h e bas is of a Zr-95 material balance and the the weight of the dr ied prec ip i ta te .

TEMPERATURE, PC

Fig. 1. Thermogravimetric curves for zirconium dibutyl phosphates.

does not account fo r all t he n i t r a t e anion, each preparation contained at l e a s t one n i t r a t e ion. In , view of the r a t i o (DBP- + NO' ) /Z~ being between .

2 and 4, i t i s -evident., that t h e precipitate's: d i d n t coJ ta in , . the i i rconyl (zrO++) grouping but contained zirconium as the Zr8+c'ation. :The varying compositions can be explained by a general formula Z ~ ( O H ) ~ ( N O ) ( D B P ) ~ i n which the only r e s t r i c t i o n i s t h a t :x + y + z = 4. The chemichyanalyses: and thermogravimetric weight l o s s of preparation C-21-1 correspond: very closely t o the formula Z ~ ( O H ) (No3) (DB~)k*l/2 H20-112 HNO . The water and 1 n i t r i c acid may be combined as ~ o l v a t e s , or, more probab y, may be merely sorbed:on and i n the solid. I n the l a t t e r case it is .fortuitous that ex- cess water and n i t r i ' c acid a re equal and add up t o 1 mole-per mole of z i r - conium dibutyl phosphiitte. , ,

The present in terpre ta t ion of analyses of zirconium dibutyl phosphate preparations i s consistent with tha t of Moffatj3 who has prepared, by adding an acetone solution of HDBP t o a 2 M HN03 solution of zirconium, a compoimd containing 14.46 Z r , 18.0% N O j , 2 9 . v C, and 5.0% H, which are very close t o , ' the theore t ica l values f o r Z r ( N O ~ ) , ~ ( D B P ) ~ .

. ,. :.+:- Only zirconium i n the Zr-95 labeled zirconium dibutyl. phosphoric adid

.<.>.I.

.preparation w a s determined. Since t h i s material, C-32-1, was prepared i n . . ,:a manner very nearly l i k e that used i n preparing- materials C-21-1 and C-27-1, . .. . . ': except t h a t C-.32-l w a s . d r ied with an - infrared lamp f o r ' 6 hr; it is. believed ,. . . . t h a t ' i t s composition corresponds t o Z r ( o H ) ( N o ~ ) ( D B P ) ~ . he theore t ica l z i r - . . .:.conium content of t h i s compound i s 15.50 wt $ as compared with the analyt ical

.', value of 12.81 wt $ zirconium i n preparation C-32-1. However,. the l a t t e r '' .. . ; . :iapzdue i s too low'on the bas i s of the Zr-95 material balance.

. '. &. . . . .I v ,.-.

. : . .

3.0 EXPERIMEWrAL PROCEDURES d

Commercial dibutyl phosphoric acid from Victor Chemicd. Company, con- t a in ing 87.7% HDBP (dibutyl phosphoric acid) and 1.8% H@P (monobutyl phosphoric acid:) with most of the remainder being water', was purif ied a s follows. ' Forty-seven m i l l i l i t e r s of,HDBP w a s heated with.10 g of act i - . vated. charcoal. 'Th i s was.diluted with 10 ml of carbon tetrachloride and f i l t e r e d . After .d i lu t ing the f i l t e r e d solution with 250 ml of car- bon tetrachloride, the HDBP was scrubbed four times with 50-ml portions. of d i s t i l l e d water t o remove. the H@P. The HJJBP was then contacted with th ree 70-ml volumes of 1.0 N NaOH, each of which converted one ' t h i rd 'of the o r ig ina l acid t o the wacer-soluble sodium .$alt. .The t h i r d extrac- t i o n yielded a . yellowish s6lu'tion with brown in te r fac ia l solids. The first two extracts , both ac id ic t o pH paper, were combined and scrubbed four times with 32-ml portions of ether t o remove organic-soluble.com- ponents. Ninety percent of the equivalent amount of n i t r i c acid and 32 m l of e ther were added and mixed. The organic phase w a s separated and the e ther ' removed under vacuum. Similarly .prepared 'materials had 'equivalent weights of 233.5, water contents of 10.8 t o 16.3$, and l e s s tlian '0.2% H$BP.

A zirconium stock solution was prepared by'.dissolving 40 g ofl A. D. McKay "pure zirconium hydroxide" i n 50 ml of hot concentrated

n i$ r i c acid . After .adding another 50 m l of acid and r&fluxing, the so l ids were allowed t o s e t t l e . The supernatant was f i l t e red . and di luted t o 200 m l . Less than 1 g. of undissolved so l ids remained. This solut ion contained 5089 M If, 0.71 M . Z r , 0.35 M Na+, and 8.20 M NO;. The sodium, as w e l l as s ~ l l - q u a n t i t i e s o f aluminuz, boron, cadmium, copper, iron, and lead, was introduced . .. from.the zirconium hydroxide.

The solutions (Table' 3 ) . in which the so lub i l i t y of zirconium dibutyl phosphate was t o be measured were .prepared from a t tock solution, contain- ing 408 'g of uranium per l i t e r and 1.02 M HEJO c :pe n i t r i c .acid,, drum

'

grade Amsco 125-82; and -sodium carbonate=-waszid. t r i b u t y l phosphate (T33P) Since some of t he solutions were t o have-higher uraniuxi/acid mole r a t i o s th.an were avai lable .in' the stock solution, UO was- prepared'.by thermal de- composition of.U04. The UO wasadded t o por ions of t he stock solut ion Z Z t o decrease the acid.concen ra t ion or t o raise the uranium concentration.

solutions with very low a c i d i t i e s were prepared from recrys ta l l i zed uranyl n i t r a t e hexahydrate . Thirty-six milliliters of 1.126 M TBP. i n &mco

- (300 g of TBP per l i t e r ) was equi l ib ra ted with f i v e succes s iv~~20-ml batches

. . of each of the 16 aque:ous soliitions. After a s ix th equi l ib ra t ion with 35 m l of aqueous solution, the phases were separated and f i l t e r e d t o remove en-.

b~ t ra ined material . P

The concentration. of zirconium dissolved i n each of the t e s t solutions .

t was. calculated from experimental gamma counting data5 and the known specif ic a c t i v i t y of Zr-95 i n preparation C-32-1.

Equilibration of the Zr-95 labeled zirconium dibutyl phosphate with .

the various solut ions was carr ied out 'as follows. About 65 mg of the dried s6,lid was added, as a mixture of powder and- small lumps, t o 20-ml portions of each aqueous or organic solution, which was contained i n a 25-ml glass- stoppered graduated >cglinder. The so l ids dispersed well i n the organic solutions but not i n ' the aqueous, solutions. An addi t iona l 130 mg was added t o each of the organic solutions a f t e r they had stood f o r 72 hr. The solut ions were then tumbled a t room temperature (20-26O~) and 2.0 rpm for 48 t o 96 hr . Samples of t he tumbled solutions were pipet ted and f i l t e r e d t4rough Whatman No.,1 f i l ter paper and analyzed. Samples IA and 2A were returned t o the tumbler af'ter sampling and tumbled f o r an addi t iona l 168 hr. Acditional so l id was added t o samples 8A, 1-0, 6-0, and 7-0 a f t e r sampling, and they, too,, were returned t o the tumblec.

.4.0.. PROCESS AP.PLICATI0NS

4 The present data and thosk of ~ ~ f f a t and Whitener . on the s o l u b i l i t y of zirconium dibutyl phosphate i n uranium nitrate-nitr ic, . :acid aqueous or .TBP-

'

hydrocarbon solutions have an immediate use in predicting the behavior'' 'o'f . zirconium i n radiochemiq31 reprocessing of nuclear fue ls . For example, a f t e r extended burnup, the r a t i o of t o t a l atoms of zirconium t o atoms of U-235 fissioned fo r na tura l uranium f i e 1 reaches a l imi t ing value7 of 0.32, corres- ponding t o 29 mg of t o t a l zirconium per mole of na tura l uranium. I f t h i s

. : . . . . .. .

Table. 3. ~ompos.itions' of ~ ~ u e o u s , and 0r&nic ~ o l u t i o n s . Pr ior t o . . .I

contacting with 'Zirconium Dibutyl' Phosphate . . . . . .

. . 0 .

Aqueous: Phase 30$ TBP-Amsco. Phase a t Equilibrium H+ ' u " H+ ' . U . ' . H Q O

L

Sample Conc, ., Conc, Density, .Sample Conc, Conc, Conc, Density, No. M - g l l No o - M g/l . 411 &/I

uranium is reprocessed i n the Purex process, the uranium content of the 1A.F stream i s about 1 . 5 M; t he associated zirconium content would be, a t most, 44 mg of zirconium l i t e r . Since the r a t i o of solvent t o feed flow r a t e i s about 5, t he zirconium content would be equivalent t o 8.8 mg of zirconium

' p e r l i t e r of solvent. Thus, t he 44 mg of zirconium per l i t e r , maximum, i n t h e feed would be close t o the so lub i l i t y l i m i t i n the aqueous phase a able 1 ) but t h e 8.8 mg per l i t e r of solvent would be well below the so lub i l i t y value of 1 t o 5 g / l i t e r . Hence, zirconium dibutyl phosphate would not prec ip i ta te from t h e extractant ; it might prec ip i ta te at the feed p la t e of a solvent ex- t r a c t i o n un i t i f the uranium concentration i s decreased suf f ic ien t ly by scrub solut ion.

1. Burger, L. L., "The Decomposition Reactions of Tributyl Phosphate and Its Diluents and ~ h e i r ' E f f e c t on Uranium Recovery Processes," Chap. 7-5 i n "Process Chemistry," Prog. i n Nuclear Energy Series 111, Pergamon Press, New York, 1958.

2. Dukes, E. K., "The Formation and Effects of Dibutyl Phosphate i n Solvent Extraction, " DP-250 (~ovember 1957).

3 - Moffat, A. Je, I h h o Chemical Processing Plant, personal communica- t ion, Aug. l b , 1959.

Moffat, A. J., and E. M. Whitener i n "Technical Progress Report for October-December 1958:'- IDO-14467 (May 19, 1959) . Reynolds, So A ., "Gamma Counting Efficiencies, " ORNL-CF-56-1-87 a an. 18, 1956) .- Rigg,,. T., and W. Wild, "Radiation Effects i n Solvent Extraction Processe.s," Ch. 7-6 i n "Process Chemistry," Frog. i n Nuclear Energy Series 111, Pergamon Press, New York, 1958.

Robinson, M. T., and J. F, Krause, Nuclear Science and Engineering, 1: 216-221' (1956).

Siddall, T. H., III, and R. M. Wallace, "Effect of Solvknt Degradation on the Purex Process," DP-286 (May 1958).

Notebook Reference

Carmichael, H. H., ORNL Notebook no. A-1737, pp. '1-54.

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27. Laboratory Records, ORNL R.C. 28. A. M. Weinberg 29. L. B. Emlet (K-25) 30. J. P. Murray (Y-12) 31. J. A. Swartout 32. E. H. Taylor 33. E. D. sh ipley

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9.6. Hanford Atomic Products Operations (L. L. Burger) 97. Idaho operat ions Office (A. J, Moffat) 98. Division of Research and Development, AEC, OR0

99-655. Given d i s t r i bu t i on as shown i n TID-4500 (15th ed,) under chemis t ry -~enera l . ca tegory (75 copies - OTS)