SEPARATION OF RARE METAL FISSION PRODUCTS AND ACTINIDES IN HIGH-LEVEL LIQUID WASTES - TOWARD THEIR NOVEL AND EXTENSIVE UTILIZATION

摘要

Hydrometallurgical separation methods such as ion exchange (IX) and electrolytic extraction (EE) are vital tools to expand reprocessing function to be capable of separation of the specific fission products (RMFP; Ru, Rh, Pd, Tc, Se and Te, etc.) and minor actinides (MA) in the spent nuclear fuel. The IX process using the tertiary pyridine resin was proposed as the novel reprocessing process with the recovery of Am and Cm individually as well as RMFP. The reprocessing experiment with a highly irradiated fast reactor MOX fuel was carried out to confirm its feasibility. The catalytic Electrolytic Extraction (CEE) method, using adding Pd{sup}(2+) cation, was applicable to recover the RMFP. The quaternary-, Pd-Ru-Rh-Re, deposit Pt electrodes showed the highest cathodic current corresponding to the hydrogen evolution reaction, ca. twice superior to that of the Pt electrode in artificial sea water as well as in alkaline solution. The recovery and separation of actinides and RMFP by IX and CEE processes will help to minimize either the amount or the quality of HLLW to be vitrified.