35 Recent Savannah River Experience and Development With Actinide Separations M. C. THOMPSON, G. A. BURNEY, and J. M. McKIBBEN Savannah River Laboratory, Ε. I. du Pont de Nemours and Company, Aiken, SC 29801
Savannah River Laboratory (SRL) and Savannah River Plant (SRP) have been i n v o l v e d in a c t i n i d e separations f o r 25 years. Work continues to upgrade processes and to initiate new processes. This r e p o r t summarizes the work since 1971 (1) except f o r the changes in enriched uranium processing reported in 1977 (2). The f o l l o w i n g t o p i c s are discussed: recovery o f americium and curium; r e d u c t i o n o f wastes by s u b s t i t u t i n g hydroxylamine n i t r a t e (HAN) f o r ferrous sulfamate (FeSA) during p a r t i t i o n i n g o f plutonium and uranium; a s o l v e n t e x t r a c t i o n flowsheet f o r recovery of Pu and Np; and improved s e p a r a t i o n o f Pu and Np with macroporous i o n exchange r e s i n s . 238
237
238
237
Recovery of Americium and Curium Large-scale p u r i f i c a t i o n of americium, curium, and cali fornium with p r e s s u r i z e d c a t i o n exchange has been planned at SRP f o r many years (1). I n i t i a l work i n v o l v e d SRP batch e x t r a c t i o n s to i s o l a t e a crude a c t i n i d e - l a n t h a n i d e f r a c t i o n followed by solvent e x t r a c t i o n and i o n exchange in the SRL high l e v e l caves (1). For l a r g e - s c a l e p u r i f i c a t i o n , a s i n g l e step was s u b s t i t u t e d f o r batch e x t r a c t i o n and s o l v e n t e x t r a c t i o n . Plant Purex solvent (30 v o l % t r i - n - b u t y l phosphate in n - p a r a f f i n ) was used to minimize f l u s h time and cross-contamination of s o l v e n t . Laboratory
Tests
A solvent e x t r a c t i o n c y c l e s i m i l a r to that used in the earlier work was s e l e c t e d (1). The flowsheet (Figure 1) was first demonstrated in l a b o r a t o r y miniature m i x e r - s e t t l e r s . Before solvent e x t r a c t i o n , the feed was t r e a t e d with manganous n i t r a t e and less than equivalent permanganate to convert plutonium to Pu(VI). Tests in miniature m i x e r - s e t t l e r s with s y n t h e t i c feed s o l u t i o n but not c o n t a i n i n g Cf showed accept ably small concentrations o f a c t i n i d e s in the aqueous waste (1AW) and organic r a f f i n a t e (1CW) streams, and a l s o acceptable s e p a r a t i o n o f plutonium from curium and americium. 0-8412-0527-2/80/47-117-515$05.00/0 © 1980 American Chemical Society
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ACTINIDE SEPARATIONS
These r e s u l t s (Table 1) show t h a t a d d i t i o n a l valence a d j u s t ment o f the feed t o reduce Pu from Pu(VI) t o the more e x t r a c t a b l e Pu(IV) was not necessary. Plutonium in the Cm-Am stream (IBP) v a r i e d from 2 t o 7.8% o f feed Pu. I n the 1C m i x e r - s e t t l e r , O.OIM HAN back-extracted Pu e f f i c i e n t l y , even when the flow o f HAN was reduced 50%, and although the feed c o n c e n t r a t i o n o f Puinthe t e s t s o l u t i o n s was M O times t h a t expected in p l a n t o p e r a t i o n .
1AF 1.5M
AI(N0 )
O.6M
HNO3
3
O.01 g / L
1AX 30%
Pu(VJ)
"(225Hii
TBP
IAS NaN0
3
1A -(loo)*
IBS AI(IM0) Να(Ν0 ) 3
30%
ICW
TBP
Waste Solvent
3
IB
(325)
IBP
IBX
Am Cm HNO3
O.1M H N O 3
1CX
ICU Pu O.3M H N O 3
O.OIM O.05M
HAN HNO3
Figure 1. Solvent extractionflowsheetfor laboratory miniature mixer settlers
Table 1.
Laboratory Tests of Am and Cm Recovery With Synthetic Feed Solution Pu
Raffinâtes Aqueous 1AW Organic Product Solutions Cm-Am IBP Pu ICU
