This report summarizes the treatment and waste form options for waste streams resulting from the electrochemical pyroprocessing of used oxide nuclear fuel. The waste treatment options presented reflect many years of research conducted both in the United States (U.S.) and South Korea (Republic of Korea -ROK). Both nations are evaluating similar advanced fuel cycles involving the treatment used nuclear fuel (UNF) for recycle, isolation of fission products for disposal, and collection of the transuranic elements (TRU) from the used fuel for transmutation in a 'burner' type fast reactor. South Korea and the U.S. have developed different management strategies for waste streams generated from the pyroprocessing of UNF. The U.S. approach involves immobilizing spent electrolytic salt containing oxidized fission products into a ceramic waste form (CWF) and both the contaminated cladding hulls and metallic fission products into a metal waste form (MWF). Both of these waste forms were developed as part of the Experimental Breeder-II (EBR-II) sodium-bonded metallic fuel treatment program. The ROK approach emphasizes product recycle and waste form volume minimization by segregating fission products recovered from process streams for immobilization in separate waste forms. This includes head-end thermal treatment of the UNF to collect volatile and semi-volatile fission products, cladding recycle, and fission product concentration or separation from LiCl or LiCl-KCl salt streams. This allows for salt recycle and for higher fission-product loading in the final waste form. A novel aspect of the ROK waste-steam management process is dechlorination of the salt waste stream performed either prior to or during waste form fabrication for a substantial reduction in waste volume.
Metal chloride waste is generated as a main waste streams in a series of electrolytic processes of a pyrochemical process. Different from carbonate or nitrate salt, metal chloride is not decomposed into oxide and chlorine but it is just vaporized. Also, it has low compatibility with conventional silicate glasses. Our research group adapted the dechlorination approach for the immobilization of waste salt. In this study, the composition of SAP (SiO 2 -Al 2 O 3 -P 2 O 5 ) was adjusted to enhance the reactivity and to simplify the solidification process as a subsequent research. The dechlorinate the LiCl-KCl waste and its reaction product could be consolidated as a monolithic form without a glass binder. The leaching test result indicated that U-SAP 1071 was more durable than other SAPs wasteform. By using U-SAP, 1 g of waste salt could generated 3 4 g of wasteform for final disposal. The final volume would be about 3 4 times lower than the glass-bonded sodalite. From these results, it could be concluded that the dechlorination approach using U-SAP would be one of prospective methods to manage the volatile waste salt.
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