Recovery of Transuranium Elements from Real High-Level Liquid Waste by Pyropartitioning Process

Abstract

A pyropartitioning process is under development to recover minor actinide elements from high-level liquid waste (HLLW) generated by Purex reprocessing. This pyropartitioning process consists of a denitration step that converts various elements in the HLLW into oxides, a chlorination step that converts the oxides into chlorides, and a reductive-extraction step that separates the actinide elements from fission products (FPs) in the chlorination product. The feasibility of each step was confirmed using simulating FPs and unirradiated transuranium elements (TRUs). In the present study, approximately 520 g of real HLLW was prepared to demonstrate the feasibility of the pyropartitioning process. Almost 100% of each TRU originally contained in the HLLW was recovered in the liquid cadmium phase in the reductive-extraction step, which showed that the expected chemical reactions were completed and the mass loss of TRUs was negligible in the denitration, chlorination, and reductive-extraction steps. The separation behaviors of actinide elements, including americium and curium, from FPs in the reductive-extraction step were quite similar to those observed in previous experiments using unirradiated materials. Hence, the pyropartitioning process was successfully verified.

Pyrochemical fuel cycle technologies for processing of spent nuclear fuels

“…The ion exchange behavior of zeolite with various cations was studied for efficient removal of FPs from the spent molten salt (Lexa and Johnson, 2001). The next step is to design an efficient and remotely applicable zeolite column for industrialized use (Uozumi et al, 2011b). Therefore, cations such as Na + must be present to compensate the charge in the framework structure.…”