Transplutonium Elements, By-Products of the Nuclear Fuel Cycle

3 Transplutonium Elements, By-Products of the Nuclear Fuel Cycle

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GÜNTER KOCH Institut für Heisse Chemie, Kernforschungszentrum Karlsruhe, D-7500 Karlsruhe, Germany WOLFGANG STOLL A L K E M GmbH, D-6450 Hanau, Germany

A r e s e a r c h and development program on the recovery and purification of p o t e n t i a l l y u s e f u l by-product a c t i n i d e s from the nuclear f u e l c y c l e was c a r r i e d out some years ago in the F e d e r a l Republic o f Germany as p a r t o f the " A c t i n i d e s P r o j e c t " (PACT). In the course o f this program, procedures f o r the recovery o f neptunium, americium and curium i s o t o p e s from power r e a c t o r f u e l s , as w e l l as procedures f o r the p r o c e s s i n g o f i r r a d i a t e d t a r g e t s o f neptunium and americium t o produce heat-source i s o t o p e s , have been developed. The h i s t o r y o f the PACT Program has been reviewed prev i o u s l y (1). Most o f the PACT activities were terminated towards the end o f 1973, when it became evident t h a t no major commercial market f o r the products in question was likely t o develop. L a t e r , development work in this field was done p r i m a r i l y with the g o a l o f removing transplutonium isotopes ( s p e c i f i c a l l y Am) and neptunium from c e r t a i n product and medium-active waste streams in order t o meet product s p e c i f i c a t i o n s , o r t o facilitate the handling o f those streams. In this regard, neptunium tends t o pose the more obvious o b s t a c l e s in nuclear f u e l r e p r o c e s s i n g flow schemes, and procedures t o improve decontamination from this e l e ment have t h e r e f o r e been q u i t e i n t e n s e l y s t u d i e d {2_, 3) . However, neptunium not being a transplutonium element, and t h e r e f o r e not f i t t i n g i n t o the scope o f this Symposium, this subject w i l l not be f u r t h e r d i s c u s s e d in this paper. Problems with ^ *Am in the 241

241 x

f u e l c y c l e o r i g i n a t e mainly from i t s build-up by decay o f ^ P u d u r i n g storage o f plutonium. Because o f i t s q u i t e intense gamma emission, ^Âm become a nuisance in plutonium f u e l s f a b r i c a t i o n by d i r e c t o r "hands-on" operations, and some decontaminat i o n from this i s o t o p e , before f u r t h e r p r o c e s s i n g o f s t o r e d p l u tonium, may become necessary in order t o reduce personnel exposure. c

a

n

Recovery o f Am and Cm from High-Level

Waste

Americium and curium i s o t o p e s formed during i r r a d i a t i o n o f nuclear r e a c t o r f u e l s are d i v e r t e d i n t o the h i g h - l e v e l waste (HLW) stream during f u e l r e p r o c e s s i n g . The HLW is thus the b i g g e s t

0097-6156/81/0161-0041$05.00/0 © 1981 American Chemical Society

Navratil and Schulz; Transplutonium Elements—Production and Recovery ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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TRANSPLUTONIUM

ELEMENTS

p o t e n t i a l source f o r these elements, and a c t i v i t i e s t o develop a process f o r the recovery o f Am and Cm from HLW were s t a r t e d in 1967. Major g u i d e l i n e s were t h a t the process t o be developed must not e s s e n t i a l l y i n c r e a s e the volume o f waste t o be processed f u r t h e r , must not use s t r o n g l y c o r r o s i v e reagents, and must be compatible with the f i n a l waste s o l i d i f i c a t i o n procedure. The development o f the recovery flowsheet, which was based on the ext r a c t i o n o f a lanthanides - a c t i n i d e s f r a c t i o n by d i ( 2 - e t h y l h e x y l ) phosphoric a c i d (HDEHP) and on a "reverse-TALSPEAK" s e p a r a t i o n o f Am and Cm from the r a r e earths, has r e c e n t l y been reviewed (J_) , so t h a t a short d e s c r i p t i o n may be s u f f i c i e n t at this p o i n t . The f i n a l v e r s i o n o f the flowsheet (4_,5_ §) is given in F i g . 1. The h i g h - l e v e l waste (designated "1WW" in F i g . 1) is d e n i t r a t e d with formic a c i d , with the goal (a) t o reduce the a c i d i t y o f the HLW down t o a value s u i t a b l e f o r HDEHP e x t r a c t i o n , and (b) t o remove "trouble-making" f i s s i o n and c o r r o s i o n products by p r e c i p i t a t i o n , thus e l i m i n a t i n g the need t o add organic complexants t o the e x t r a c t i o n feed. C o n d i t i o n s were chosen such t h a t Am, Cm and r a r e earths (R.E.) remained in s o l u t i o n while most o f the Zr, Nb, Mo, noble metals, and Fe were p r e c i p i t a t e d . The s o l i d sludge could be f i l t e r e d o f f and the f i l t r a t e fed t o the s o l v e n t e x t r a c t i o n c y c l e , u s i n g 0.3 M HDEHP (extractant) + 0.2 M TBP (modifier) in a n-alkane d i l u e n t as the s o l v e n t . Am, Cm and R.E.'s were e x t r a c t e d in the WA c o n t a c t o r from the non-complexed feed, Am and Cm were p a r t i t i o n e d from the R.E. s in the WB contactor i n t o 0.05 M d i e t h y l e n e t r i a m i n e pentaacetate (DTPA)/1M l a c t i c a c i d , R.E.'s were r e - e x t r a c t e d from the s o l v e n t in the WC contactor by 5 M n i t r i c a c i d , and the Am/Cm product s o l u t i o n from WB was f u r t h e r p u r i f i e d from R.E.' s by an a d d i t i o n a l organic s o l v e n t scrub stream in the WD c o n t a c t o r . F o r the f i n a l p u r i f i c a t i o n and c o n c e n t r a t i o n o f the Am + Cm product a c a t i o n exchange process was developed. Separation o f the Am from Cm, i f necessary, might be performed by the Hanford c a t i o n exchange process (7,8), by high-pressure c a t i o n exchange (9-11), o r by potassium americium (V) carbonate p r e c i p i t a t i o n (12); f o r reviews o f these procedures see r e f e r e n c e s 13 and 14. In l a b o r a t o r y t e s t s using simulated HLW s o l u t i o n spiked with f i s s i o n product t r a c e r s , Am and Cm, the d e n i t r a t i o n step proved t o be a s e n s i t i v e process, but Am/Cm r e c o v e r i e s o f ca. 90%inthe aqueous supernate c o u l d be r e a l i z e d under optimized c o n d i t i o n s . Decontamination f a c t o r s (DF) > 1000 f o r Zr, Nb, Mo, and ^ 100 f o r Ru and Fe were obtained in the p r e c i p i t a t i o n step. The s o l v e n t ext r a c t i o n c y c l e gave > 98% recovery o f Am/Cm and DF > 10^ f o r r a r e e a r t h s , Sr and Cs. Appreciable decontamination was a l s o obtained f o r Zr/Nb (DF = 20), Ru (50), U (650), Pu (250), Np (800) and Fe (420). The i o n exchange c y c l e served mainly f o r Am-Cm concentrat i o n and f o r removal o f DTPA and l a c t i c a c i d ; based on t e s t s with europium as a s t a n d - i n f o r t r i v a l e n t a c t i n i d e s , c o n c e n t r a t i o n f a c t o r s o f about 50 could be expected under optimized c o n d i t i o n s . Planning o f a p i l o t p l a n t f o r the recovery o f Am and Cm was s t a r t e d . The name ISAAC (from the German "Isolierungs-Anlage f u r r

1


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43

By-Products

to Off-gas Treatment

Glass Blocks, **to final Storage

to MAW Treatment

|WC(RE BQck-extroctkxi)| |WBRE}— v/—[WDX|

|WCRE|

|WCW1

lAqu Wash I I Liquor |

I WD(Purification) 1 [WDACJ[wow]

Solvent Clean-up

Τ - | w a s hyeà Sdventl >ea boiventj

S

p

e

n

t

A

q

u

to MAW Treatment

|Preporation|

^ têt

pÂW|

X

* *

11AAC f

to MAW Treatment

American Chemical Society

Figure 1. Flowsheet for Am-Cm recovery from high-level waste (1WW) solutions (1). For a list of compositions and flow rates of the process streams see References 4 and 5.


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Americium und C u r i u m ) was given t o this p i l o t p r o j e c t (4) . These p l a n s were abandoned when the PACT p r o j e c t was terminated in 1973. Thus, demonstration o f the s e p a r a t i o n process with a c t u a l HLW is l a c k i n g , and no judgement can be made on i t s performance. Recovery o f

Am from s t o r e d Plutonium

T h i s work was s t a r t e d with the aim o f r e c o v e r i n g some o f the *Am which is formed during storage o f plutonium, without impos i n g any t r o u b l e t o the f u e l element f a b r i c a t i o n process i t s e l f (J_). A p o s s i b l e source o f m a t e r i a l is the plutonium-fuel f a b r i c a t i o n scrap which at the ALKEM p l a n t is c o l l e c t e d f o r recovery o f p l u tonium values by anion exchange. The e f f l u e n t from the anion exchange column c o n t a i n s the americium, together with uranium, c o r r o s i o n products, r e s i d u e s from chemical reagents, and non-recovered plutonium. For the recovery o f Am (and Pu) from the conc e n t r a t e d e f f l u e n t s , a process based on o x a l a t e p r e c i p i t a t i o n and s o l v e n t e x t r a c t i o n with t r i c a p r y l methyl ammonium n i t r a t e , TCMAN ( n i t r a t e form o f Aliquat-336, a product o f General M i l l s Inc.) was operated f o r some time in a s m a l l - s c a l e facility equipped with p u l s e d g l a s s columns (15,16). The concentrated e f f l u e n t s were adj u s t e d t o 6 t o 7 M HNO3, and the U and Pu were e x t r a c t e d in the f i r s t column by 0.5 M TCMAN d i s s o l v e d in Sovesso-100, a h i g h b o i l i n g aromatic d i l u e n t produced by Exxon Co. U and Pu were backe x t r a c t e d in a second column i n t o an a c e t i c a c i d - hydroxylamine s u l f a t e s o l u t i o n . The e f f l u e n t from the f i r s t column was s a t u r a t e d with o x a l i c a c i d and n e u t r a l i z e d with ammonia t o pH = 2.5. A n e a r l y white p r e c i p i t a t e o f Am and Ca o x a l a t e s was obtained while most o f the m e t a l l i c contaminants (e.g., Fe, Cr, Al) r e mained in s o l u t i o n as s t a b l e o x a l a t o complexes. The p r e c i p i t a t e was f i l t e r e d o f f , dissoved in b o i l i n g concentrated n i t r i c a c i d t o d e s t r o y the o x a l a t e , n e u t r a l i z e d with ammonia t o pH = 2.5 t o 3, and the Am was e x t r a c t e d from the s t r o n g l y s a l t e d aqueous ammonium n i t r a t e s o l u t i o n by 0.5 M TCMAN/Solvesso. The loaded organic s o l vent was scrubbed with concentrated ammonium n i t r a t e s o l u t i o n , and the americium was back-extracted with d i l u t e n i t r i c a c i d , p r e c i p i t a t e d as the o x a l a t e , and converted i n t o Am0 by c a l c i n a t i o n at 800°C. Multi-gram amounts o f A m have been prepared with this procedure, with Am p u r i t i e s > 99%. 24

2

241

M o d i f i c a t i o n i n t o T e c h n i c a l - s c a l e Operation U t i l i z a t i o n o f plutonium in e a r l y research and commercial orders t o f a b r i c a t e thermal r e c y c l e and f a s t breeder f u e l s d i d not c o i n c i d e in t i m i n g with Pu a v a i l a b i l i t y from d i f f e r e n t sources. The plutonium comes mainly from high-exposure l i g h t - w a t e r r e a c t o r f u e l r e p r o c e s s i n g ; extended storage o f this Pu as a n i t r a t e s o l u t i o n leads t o A m contents up t o 3%. For hands-on o p e r a t i o n with this m a t e r i a l it is necessary t o reduce the Am content t o about 0.5%. I t was a l s o necessary t o minimize the l i q u i d waste streams from the p l a n t . In d e s i g n i n g a t e c h n i c a l - s c a l e process, it was 241


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A N D STOLL

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45

e s s e n t i a l t o both u t i l i z e an e x i s t i n g p r e c i p i t a t o r and a v o i d flammable l i q u i d s f o r the main product stream. The flow scheme o f the process(17) is represented in F i g . 2 . The r e q u i r e d throughput r a t e o f 5 kg Pu/day is obtained in a batch-type o p e r a t i o n , where a 5 t o 10% substoichometric o x a l a t e p r e c i p i t a t i o n is performed by adding s o l i d o x a l i c a c i d t o a 3 M H N 0 - 100 g/L P u ( N 0 ) s o l u t i o n at 80°C in about 2 hours. Up t o 95% o f the Pu is p r e c i p i t a t e d as uniform c r y s t a l s o f 20 yum average s i z e and f i l t e r e d . A f t e r washing and c a l c i n a t i o n , the average a n a l y s i s o f this product shows l e s s than 1000 ppm t o t a l m e t a l l i c i m p u r i t i e s . When evaporating the f i l t r a t e t o about 5% o f i t s o r i g i n a l volume, n i t r i c a c i d is recovered, and most o f the o x a l i c a c i d is destroyed. T h i s r e s u l t s from sump temperatures o f up t o 123°C and the presence o f Pu(VI). The concentrated f i l t r a t e is adjusted t o 7 M HNO^ and passed over Permutit SK anion exchange r e s i n t o f i x the remaining Pu. Plutonium is e l u t e d with 0 . 6 M HNO3, evaporated, and added t o t h e main Pu stream. Americium p a s s i n g the r e s i n bed together with m e t a l l i c i m p u r i t i e s is evaporated t o a s o l u t i o n c o n t a i n i n g 20 g/L Am(III) n i t r a t e and all the c o r r o s i o n products and i m p u r i t i e s from storage and p r o c e s s i n g . T h i s s o l u t i o n is s a t u r a t e d with s o l i d o x a l i c a c i d (^ 20 f o l d the s t o i c h i o m e t r i c amount o f the contained Am) at pH = 1.5. The r e s u l t i n g p r e c i p i t a t e when s e t t l e d is r e d i s s o l v e d in concentrated n i t r i c a c i d , and is r e p r e c i p i t a t e d with ammonium o x a l a t e at pH = 1. S t i r r i n g the s e t t l e d o x a l a t e twice w i t h 0 . 2 M ammonium o x a l a t e s o l u t i o n at a pH o f about 10 reduces the m e t a l l i c i m p u r i t i e s ( e s p e c i a l l y N i , Fe and Zn) so t h a t > 99% pure Am0 is obtained a f t e r c a l c i n a t i o n . I t is noteworthy t h a t this process does not c r e a t e any a d d i t i o n a l s o l i d waste, as all c o n s t i t u e n t s o f the waste s o l u t i o n can e i t h e r be recovered by d e s t i n a t i o n , o r c h e m i c a l l y decomposed at r e l a t i v e l y moderate temperatures. C o r r o s i o n a t t a c k is small because no halogen compounds a r e i n v o l v e d , and the o n l y p o t e n t i a l l y hazardous m a t e r i a l is the i o n exchange r e s i n . When operated at room t e mperature, there are no d e t e c t a b l e s i g n s o f decompos i t i o n w i t h i n one t o two month's residence time. The spent r e s i n can be s t o r e d s a f e l y in a l k a l i n e media before i n c o r p o r a t i o n i n t o concrete. T h i s r e l a t i v e l y simple process has operated s u c c e s s f u l l y d u r i n g 6 years w i t h a t o t a l throughput o f about 500 kg Pu and about 3 kg Am. 3

3

4

2

Pu/Am Separation by E x t r a c t i o n Chromatography T h i s study was c a r r i e d out in order t o evaluate the a p p l i c a b i l i t y o f e x t r a c t i o n chromatography, with TBP as the e x t r a c t i n g agent, i n s t e a d o£ anion exchange f o r e f f i c i e n t p u r i f i c a t i o n o f plutonium from *Am (18,19). The r e s i n used was Levextrel-TBP, a product o f Bayer AG, Leverkusen, Germany. The L e v e x t r e l s a r e styrene - d i v i n y l b e n z e n e - based r e s i n s which are copolymerized 2


TRANSPLUTONIUM

(

PuHW ) 3

t

CONVERSION

)

(

Pu(N03); Solution

IC00H)

BOg/l Pu

Solid

Fv-Affi SEPARATION

)

(

Am

2

(C00H) Solid

2

Concentrate

3M HN03

)

I

»H3

1

20g/LAm

Prec pitotor O'C

Exchange Column (Permutit SK R« tin)

J

cone

Evaporotor

Precipitator pH-2.5

HNO 3 Settling tank |Reditîolver [•

PulN03Û|—I Solution Mg/LPu

[

(NHO2(C00)2

Filling

I

Evope rater

Settling tank

Sieving

I Solidification I Concrete

Evapo-

1 p»o? 1

Figure 2.

Am CONVERSION

ELEMENTS

rator

Pu - Am Concentrate -SOg/lPu -10g/LAm

Integrated flowsheet used at the ALKEM plant for plutonium nitrate conversion combined with A m separation and conversion 241


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in the presence o f the r e s p e c t i v e e x t r a c t a n t , e.g. TBP(20). These r e s i n s o f f e r the advantage t h a t the e x t r a c t i n g agent is b e t t e r f i x e d in the matrix m a t e r i a l than is the case with e x t r a c t a n t s simply sorbed on u s u a l c a r r i e r m a t e r i a l s ; this is o f p a r t i c u l a r importance when t e c h n i c a l - s c a l e a p p l i c a t i o n s o f e x t r a c t i o n chro matography are envisaged. S o l i d Pu0 is the p r e f e r r e d form f o r intermediate storage of plutonium . For d i s s o l u t i o n o f P U O 2 in n i t r i c a c i d , f l u o r i d e ion must be added as a c a t a l y s t . The d i s t r i b u t i o n c o e f f i c i e n t s o f Pu(IV) between Levextrel-TBP and n i t r i c acid(18) are c o n s i d e r a b l y reduced when F~ i o n is present. T h i s e f f e c t can be counteracted by a d d i t i o n o f Al3+ i o n f o r complexation o f F~; an A l 3 F ~ ratio of 1 is s u f f i c i e n t f o r a s a t i s f a c t o r y s o r p t i o n o f Pu (19). Maximum l o a d i n g s o f 140 g/L r e s i n have been obtained. L a b o r a t o r y - s c a l e column experiments, u s i n g two r e s i n columns in s e r i e s , were performed with feed s o l u t i o n s c o n t a i n i n g 25 g/L Pu, 90 mg/L Am, 6 M HNO3, Ο t o 0.55 M F , and Ο t o 0.19 Μ Α 1 ( Ν 0 ) · With a flow r a t e o f 5 mL/cm . min, l o a d i n g s o f 100 t o 120 g Pu/L r e s i n were obtained on the f i r s t column. The e f f l u e n t from the f i r s t column contained 11 t o 22% o f the Pu while t h a t from the 2nd column contained 0.02 t o 0.9% o f the Pu. Washing with 5 M HNO3/ 0.1 M Al(NO3)3 s o l u t i o n reduced the f l u o r i d e c o n c e n t r a t i o n t o the s p e c i f i e d value (< 100 ppm). E l u t i o n o f the 1st column with 3 bed volumes o f 0.3 t o 0.5 M HNO3 removed 69 t o 87% o f the Pu from the column, with Am contents c o n s i s t e n t l y lower than the s p e c i f i e d value o f 100 ppm. Decontamination f a c t o r s up t o 350 f o r Am and up t o 50 f o r F~ were measured. For t e c h n i c a l a p p l i c a t i o n s , knowledge o f the i r r a d i a t i o n be haviour o f the Levextrel-TBP r e s i n is important. A d e t a i l e d study c a r r i e d out at the Radiochemistry I n s t i t u t e o f the T e c h n i c a l Uni v e r s i t y , Munich(21,22), showed t h a t with gamma i r r a d i a t i o n the formation r a t e o f d i b u t y l phosphoric a c i d (HDBP) and o f "non-remo v a b l e " a c i d i c r a d i o l y s i s products ("do-bads") is 2 t o 5 times lower with Levextrel-TBP r e s i n than with pure TBP; the e f f e c t is a t t r i b u t e d t o the "scavanger" a c t i o n o f the aromatic groups in the matrix m a t e r i a l . In summary, a high r a d i a t i o n r e s i s t a n c e o f t h e r e s i n has become evident. A r e f e r e n c e flowsheet f o r t e c h n i c a l - s c a l e o p e r a t i o n o f this p r o c e s s , u s i n g t h r e e columns in s e r i e s , has been proposed(19). In Step 1 ( l o a d i n g ) , t h e feed s o l u t i o n (ca. 25 g/L Pu(IV), 3 t o 6 M HNO3, t r a c e s o f Am and F*, with A 1 ( N 0 ) added t o A l : F = 3) is fed at room temperature t o the bottom o f C o l . 1 with a f l o w - r a t e of < 3 mL/cm . min. The feed flow is stopped when the Pu concen t r a t i o n in the e f f l u e n t from C o l . 1 becomes > 70% o f t h a t o f the feed; a l o a d i n g o f 120 t o 140 g Pu/L r e s i n is obtained under this c o n d i t i o n . In Step 2 (scrub), 3 t o 5 bed volumes o f 5 M HNO3 is fed w i t h a flow r a t e < 3 mL/cm^ -min t o the bottom o f C o l . 1, with C o l s . 2 and 3 s t i l l in s e r i e s . In Step 3 ( e l u t i o n ) , C o l . 1 is d i s connected from C o l s . 2 and 3, and > 90% o f the plutonium is e l u t e d from C o l . 1 w i t h 3 t o 4 bed volumes o f 0.3 M HNO^ (50°C) in down2

+

:

-

3

2

3+

3

3

2

Amerlcan Cfïemlcal Society Library 1155 Î6th St. N. Yi. Navratil and Schulz; Transplutonium Elements—Production and Recovery Washington, D. C* Society: 20030 Washington, DC, 1981. ACS Symposium Series; American Chemical

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flow d i r c t i o n , with a f l o w - r a t e < 1 c e n t r a t e d Pu p r o c u c t . The column is a d d i t i o n a l 0.3 M HNO^; the t a i l i n g s the feed to the next c y c l e in which column, e t c .

mL/cm^ · min, t o g i v e a conwashed f r e e from Pu with are r e c y c l e d and combined with C o l . 2 becomes the loaded

241 Processing of Neutron-irradiated

Am

Targets

In the scope o f the PACT p r o j e c t , a program was followed on the p r o d u c t i o n o f medical-grade ^ 8 p by neutron i r r a d i a t i o n o f Âm and glpha decay o f the C m produced. T h i s route would o f f e r a ^ Pu product which is e s s e n t i a l l y f r e e from 236p j is thus s u i t a b l e f o r l a r g e medical power sources, e.g., f o r an a r t i f i c i a l h e a r t . The process which was s t u d i e d f o r the chemical proc e s s i n g o f i r r a d i a t e d AmC>2 - A l cermet t a r g e t s (23) has r e c e n t l y been reviewed(1); it c o n s i s t e d of the f o l l o w i n g steps : 2

u

2

4

2 4 2

2

Uf

a

n

(

(a) Aluminum, is d i s s o l v e d with 8 M NaOH. (b) The NaOH s o l u t i o n is f i l t e r e d o f f , and the Am0 r e s i d u e is d i s s o l v e d with 9 M n i t r i c a c i d . (c) Pu is adjusted t o Pu(IV) and sorbed on Dowex 1X4 (< 400 mesh) r e s i n on a high-pressure ion-exchange column. The column is washed with 7 M n i t r i c a c i d , and the Pu is e l u t e d with 0.5 M n i t r i c acid. (d) Pu is f u r t h e r p u r i f i e d by a second high-pressure anion exchange c y c l e . (e) For recovery o f Am the e f f l u e n t o f the f i r s t anion exchange c y c l e is d e n i t r a t e d by formic a c i d t o 0.5 M hydrogen i o n (23). (f) Am is sorbed together with r a r e earths (R.E.) and r e s i d u a l Cm on a high-pressure c a t i o n exchange column u s i n g AG 50X12 r e s i n (21 t o 29 yam p a r t i c l e s i z e ) . The a d s o r p t i o n column is washed f r e e from other f i s s i o n products with 0.5 M NË^NO^ solution. (g) Am is separated from Cm and R.E.'s by chromatographic e l u t i o n w i t h 0.5 M α-hydroxy i s o b u t y r i c a c i d (pH = 3.45) through a high-pressure s e p a r a t i o n column loaded with AG 50X12 r e s i n (21 t o 29 yum) . 2

L a b o r a t o r y - s c a l e t e s t s with s i n g l e i r r a d i a t e d Am0 -Al cermet p e l l e t s showed t h a t the d i s s o l u t i o n gime o f the aluminum matrix must be kept t o a minimum because ^ Pu l o s s e s i n c r e a s e d s e v e r e l y w i t h i n c r e a s i n g c o n t a c t time o f the concentrated NaOH. Proper ad justment o f the plutonium valency was important t o minimize 238p l o s s e s in the anion exchange s e p a r a t i o n ; l o s s e s i n c r e a s e d with i n c r e a s i n g 242cm c o n c e n t r a t i o n and, hence, alpha i r r a d i a t i o n dose. Treatment of the feed s o l u t i o n with hydrogen peroxide followed by b o i l i n g f o r 1 h and immediate p r o c e s s i n g through the anion ex change column kept t h e ^ ^ S p u l o s s e s down to about 5%. 90 to 98% Âm and 85 t o 95% Cm were recovered in the high-pressure c a t i o n exchange step, with DF's o f lOO to 300 f o r ^ Z r - ^ Nb, 2

2

u

2

4

2

9


5

3.

KOCH A N D STOLL

i V J

> 200 f o r

Ru -

Nuclear

iW,J

Fuel

Cycle

49

By-Products

R u and > 10000 f o r other f i s s i o n products.

References 1.

Koch, G.; "Recovery o f by-product a c t i n i d e s from power r e a c t o r f u e l s and p r o d u c t i o n o f heat-source i s o t o p e s " , ACS Sympos. Ser. No. 117 (1980), p. 411.

2.

Ochsenfeld, W.; Baumgärtner, F.; Bauder, U.; B l e y l , H.J.; Ertel, D.; Koch, G.; Proc. I n t e r n a t . Solv. E x t r a c t . Conf. ISEC 1977, vol. 2, p. 605; German Report KFK-2558 (1977).

3.

K o l a r i k , Z.; Ochsenfeld, W.; KFK-Nachr. 11 (1979) No. 3,34

4.

Koch, G.; German r e p o r t KFK-1656 (1972) p. 1-10.

5.

Koch, G.; K o l a r i k , Z.; Haug, H.; H i l d , W.; Drobnik, S.; German r e p o r t KFK-1651 (1972).

6.

Koch, G.; K o l a r i k , Z.; Haug, H.; Radiochimiya (USSR) 17 (1975) 601; J. Inorg. Nucl. Chem., Suppl. 1976, 165.

7.

Wheelwright, E . J . ; Roberts, F.P.; Bray, L.A.; USA r e p o r t BNWL-SA-1492 (1968).

8.

Wheelwright,

9.

Campbell, D.O.; Ind. Eng. Chem. Process Design 9 (1970) 95.

10.

Hale, W.H.; Lowe, J.T.; Inorg. Nucl. Chem. L e t t e r s 5 (1969) 363.

11.

Lowe, J.T.; Hale, W.H.; Hallmann, D.F.; Ind. Eng. Chem. Process Design Develop. 10 (1971) 131.

12.

Burney, G.A.; Nucl. App. 4 (1968) 217.

13.

Vaughen, V.C.A.; "Recovery o f Americium and Curium", in: Koch, G. (ed.), "Transuranium Elements", P a r t A1 I I , System No. 71 o f "Gmelin Handbook o f Inorganic Chemistry", Supplement V o l . 7b, p. 315-326, Springer, B e r l i n - H e i d e l b e r g New York 1974.

14.

Schulz, W.W.; "The Chemistry o f Americium", ERDA Crit. Rev. Ser., TID 26971 (1976).

15.

Koch, G.; Schön, J.; German r e p o r t KFK-783

16.

S c h e f f l e r , K.; Kuhn, K.D.; Koch, G.; Schön, J.; Reaktortagung, B e r l i n 1970, Proceedings p. 534.

-

E . J . ; Roberts, F.P.; USA r e p o r t BNWL-1072

(1969).

Develop.

(1968).


50

TRANSPLUTONIUM ELEMENTS

17.

Schneider, V.; Koch, K.H. (ALKEM GmbH, Hanau); unpublished.

18.

Ochsenfeld, W.; Schön, J.; Smits, D.; Tullius, E.; Kerntechnik 18 (1976) 258. Ochsenfeld, W.; Schön, J.; Reaktortagung, Mannheim 1977, Proceedings p. 381.

19.

E s c h r i c h , H.; Ochsenfeld, W.; Separation Science and Technology

15 (1980) 697.

20.

Kroebel, R.; Meyer, A.; German patent a p p l i c a t i o n DE-OS 2.162.951 (18 Dec. 1971).

21.

de Waha, R.; Specht, S. (Technical U n i v e r s i t y , unpublished.

22.

Weh, R.; Specht, S. (Technical U n i v e r s i t y ,

23.

Weinländer, W.; B u m i l l e r , W.; German r e p o r t KFK-1849 (1974) p. 54, and unpublished work r e p o r t e d in r e f . (1).

RECEIVED

Munich);

Munich);

December 30, 1980.


Transplutonium Elements, By-Products of the Nuclear Fuel Cycle

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