Strategic Separation of Technetium and Rare Metal Fission Products in Spent Nuclear Fuel: Solvent Extraction Behavior and Partitioning by Catalytic Electrolytic Extraction

Extraction behavior of Tc in the PUREX process was discussed on the basis of the observations at TRP, a semi-industrial scale reprocessing plant for spent LWR fuel in Tokai-mura. The Tc extraction in the HA/HS banks of the TRP was significantly enhanced by the coextraction with Zr(IV), while more than 99% of Tc was finally acccumulated in HLLW. Catalytic electrolytic extraction (CEE) was studied to separate Pd, Ru, Rh, Tc, Te, and Se, categorized as rare metal fission products (RMFP) in the HLLW. Cyclic reaction of metallic cations such as Pd2+ or Fe2+ can accelerate the electrochemical deposition of RuNO3+, Rh3+, and ReO4- owing, e.g., to the promoting effect of Pd adatoms or to behavior of Pd as mediator. Apart from being the first step for transmutation or other selective strategies for radioactive waste management containing long-lived fission products, the RMFP separation also offers alternative material resources to meet expanding demands for catalysts in fuel cell/hydrogen soft energy systems. Extended recycling of RMFPs is proposed as a new strategy on nuclear fuel reprocessing.