Development of Hybrid Reprocessing Technology Based on Solvent Extraction and Pyrochemical Electrolysis

Abstract

Toshiba has been proposing a new fuel cycle concept for a transition period from LWR to FR. This concept has a higher proliferation resistance for a fuel cycle than for a conventional cycle because plutonium could be recovered with minor actinides. Toshiba has been developing a new advanced hybrid process technology with solvent extraction and pyrochemical electrolysis of spent fuel reprocessing for a transition period from LWR to FR. The advanced hybrid process combines the solvent extraction of the LWR spent fuel in nitric acid to recover pure uranium and the pyrochemical electrolysis in molten salts to recover impure plutonium with minor actinides. Highly pure uranium is used for LWR fuel and impure plutonium with minor actinides for metallic FR fuel. The pyrochemical process for the FR fuel recycle system is based on the research on the electrorefining process in molten salts since 1988 in cooperation with Central Research Institute of Electric Power Industry (CRIEPI). The solvent extraction test with an electrolytic reduction test using actual LWR spent fuel and an oxalate precipitation test were carried out to confirm the feasibility of the new advanced hybrid process. The electrolytic reduction test was conducted to investigate the impurity of uranium recovery and the oxalate precipitation test to evaluate the recovery yield of plutonium with minor actinides. The results suggest that the purity of recovered uranium (U) and the recovery yield of plutonium with a minor actinide (Pu+MA) could achieve the target value in a stage (U purity: 99.97%, Pu+MA recovery yield: 99.9%).