Fuel and Blanket Processing Development for Molten Salt Breeder Reactors.

Abstract

Evaluations of Molten Salt Breeder Reactors have pointed t h e direction of desirable design, research, and development f o r improving t h e economic and breeding performance of these systems, In design, t h e conventional concept of processing f u e l i n f a c i l i t i e s t h a t are separate from t h e reactor plant needs t o be abandoned i n favor of integrating t h e processing operations d i r e c t l y i n t o the reactor building. For the MSBR, only a small spaoe i s required adjacent t o the reactor c e l l s f o r processing c e l l s . This arrangement allows significant savings i n capital, operating;, shipping, and inventory costs.Research and development have shown t h a t i r r a d i a t e d MSBR f u e l can be decontaminated i n a f our-step process consisting of fluorination, UF6 sorption, vacuum d i s t f l l a t i o n , and reduction-reconstitution, These operations recover not only the uranium but a l s o the LiF-BeF2 c a r r i e r , Fluorination and sorption technologies are well developed f o r batchwise operation, having; advanced through the p i l o t plant stage. However, f o r MSBR application, these two steps, a s well a s d i s t i l l a t i o n and reduction-reconstituti~n~must be developed f o r continuous operation. These four unit processes a r e rather simple and straightforward; however, vacuum d i s t i l l a t i o n requires a higher temperature (-1000" C ) than has been encountered previously i n molten salt processing . DISCLAIMERThis 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. DISCLAIMERPortions of this document may be illegible in electronic image products. Images are produced from the best available original document. 1 2 I F e r t i l e stream processing s t e p s c o n s i s t of protactinium removal, f l u o r i n a t i o n , and UF6 sorption, Protactinium removal i s s i n g u l a r l y important because of t h e improved breeding performancewithlow protactinium concentrations i n t h e f e r t i l e stream. R e l a t i v e l y high processing r a t e s a r e required. Xenon poisoning i s kept low by i n j e c t i n g a purge gas d i r e c t l y i n t o t h e c i r c u l a t i n g f u e l stream. An i n -l i n e s t r i p p e r removes the gases, ...

Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

“…75 Results from these experiments were used to inform the design of the waste handling system of the MSBR. 76 Vacuum distillation achieves better separation at lower temperatures.…”

Gas-phase molybdenum-99 separation from uranium dioxide by fluoride volatility using nitrogen trifluoride

“…In most of the proposed uorination methods such as the FLUOREX process, 4 or those described earlier by workers in the Czech Republic, 5 the former Soviet Union, 6 or the US, [7][8][9] uorine gas is used to rapidly form volatile UF 6 from an irradiated matrix, generally UO 2 or U metal 10 A large set of volatile uoride products such as PuF 6 , NpF 6 , IF x (for x ¼ 3, 5, 7), TeF 6 , TcF 6 , etc., can be binned cryogenically, or can be sorbed onto solid traps that have specic capture affinities for the volatile products. 10,11 Regardless of the exact process used, uorination requires the use of rigorously closed reactor and trapping systems. These systems are thus more suited to complete trapping of volatile ssion products than the liquid digestion processes currently in use.…”