Countercurrent Extraction Test with Continuous Flow of Molten LiCl-KCl Salt and Liquid Cd for Pyro-Reprocessing of Metal FBR Fuel

Abstract

The three-stage countercurrent extraction test with molten LiCl-KCl and liquid Cd was carried out for the development of spent salt treatment process in pyrometallurgical reprocessing of metal FBR fuel. Both salt and Cd solvent were supplied successively from each feed tank into the extractor at a constant flow rate and recovered separately into individual recovery tanks. Uranium, transuranic elements, and rareearth elements were substituted by Ce, Gd, and Y, respectively. More than 98% of Ce and 93% of Gd were recovered, and 27% of Y was corecovered in the Cd solvent. The separation factors of Gd and Y against Ce were evaluated to be 0.28–0.29 and 0.0057–0.0073, respectively. The former is almost equal to and the latter is better than that in the equilibrium. As the connecting part between each stage had a simple structure, a small amount of Cd in each stage mixed with that in the neighboring stage, which made the separation efficiency lower than expected. A calculation study showed the relationship between the Cd mixing rate and recovery yield or separation factor, and it showed that the recovery yield and separation efficiency were expected to be much improved by the modification of the connecting part to prevent Cd from mixing.