Fig. 11-1 Flow of U, Pu, TRU and FP The concept of partitioning and trans-mutation involves separation of useful elements and long-lived radioactive nu-clides from high-level radioactive waste (HLW), utilization of useful elements, and nuclear transforma-tion of long-lived nu-clides into shorter-lived or stable ones. The development of partitioning and trans-mutation technology will offer the possi-bility of utilizing HLW as a useful resource and a promising option to further im-prove the efficiency and safety of future HLW management.

Operation of nuclear power reactors produces highly radioactive transuranic elements (TRU) and fission products within the fuel. After the reprocessing of spent fuel, these undesirable substances appear in the high-level radioactive waste(HLW). The radioactivity of HLW decreases naturally by radioactive decay, but it takes a very long time to reach a reasonably low level. Therefore, the management and disposal of HLW has become one of the most important issues in the development and utilization of nuclear power. Partitioning refers to a process or act to separate and recover the long-lived radioactive nuclides from HLW. Transmutation is nuclear transformation of long-lived radioactive nuclides into shorter-lived nuclides or stable (nonradioactive) nuclides. The development of partitioning and transmutation technology offers a promising option to further improve the efficiency and safety of HLW disposal. Partitioning and transmutation research, called for under the national "long-term research and development program on partitioning and transmutation technology," started in 1989. JAERI, PNC, and CRIEPI participate this program, known as the "OMEGA" program. The initiation of the Japanese OMEGA program has stimulated much global interest in partitioning and transmutation. France and other countries now have initiated their own similar national programs. Partitioning research at JAERI involves development of an aqueous process that separates HLW into four basic groups; the TRU group, the strontium and cesium group, the noble metals group, and the remaining elements (others) group. JAERI is pursuing transmutation with dedicated systems, accelerator-driven systems and burner reactors, that are specially designed to efficiently and effectively transmute a large quanity of long-lived radioactive nuclides within a short time period. In parallel, development of an intense proton accelerator and collection of a basic data base are ongoing. To conduct this research efficiently, JAERI has placed emphasis on domestic collaboration and international cooperation within the frameworks of OECD/NEA and IAEA.

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