Methods for Recovering Molybdenum from High-Level Raffinate of Extraction Reprocessing of NPP Spent Fuel

A large set of experimental data obtained previously with real industrial products and model solutions were analyzed, and problems related to formation of precipitates of fission molybdenum compounds in various steps of NPP spent fuel reprocessing were outlined. Molybdenum-containing precipitates prevent partitioning of long-lived radionuclides from the raffinate of the first extraction cycle of spent fuel reprocessing. Comparative analysis of methods (precipitation, sorption, extraction) for removing molybdenum from this raffinate was performed, and flowsheets involving localization of Mo using a TBP-compatible extractant with acid additives were suggested. An experimental study was made on precipitation of molybdenum from its backwash, followed by preparation of nonvolatile forms suitable for incorporation by hot pressing, together with the other long-lived radionuclides, into polycrystalline matrices for long-term storage.