Molten fluoride salt and liquid metal multistage extraction model

Abstract

A multistage extraction model based on the distribution of actinides and rare earths between two phases of lithium activated bismuth and molten LiFBeF2 (66 mole % LiF) has been developed. The model shows that the distribution across the cascade is affected by the concentration of Li in the metal phase, system temperature, flow rates of each phase, and the presence and concentration of other elements in the molten salt phase. Based on the model, it is predicted that an online molten salt coolant purification system could be used to separate both rare earths and actinides from the primary salt coolant in fluoride salt-cooled high-temperature reactors (FHRs). Additionally, the results provide sufficient evidence that this extraction method can separate primarily actinides prior to extraction of other rare earth elements, which would allow for fission products and other reactor poisons to be discarded, while fuel materials (U and Pu) can be recycled back into a reactor system.