HEU Minimization on Research Reactors in JAEA

Conversion of the research reactors (RRs) from use of highly enriched uranium (HEU) fuel to low enriched uranium (LEU) fuel is one of the most effective measures to minimize HEU and recently world widely accelerated due to growing nuclear security concerns. In international community, HEU/LEU conversion of RRs is placed one of the missions of Global Threat Reduction Initiative(GTRI), initiated in 2004, and at the 2010/2012 Nuclear Security Summit (NSS), the Participating States agreed "encourage the conversion of reactors from HEU to LEU fuel and minimization of use of HEU, where technically and economically feasible." The Japan Atomic Energy Agency (JAEA) has been operating many RRs and has already started a study on reducing of enrichment of RRs in 1979, with creating of a fuel enrichment reduction plan. These RRs were successfully converted to LEU or reduced to 45% (then shut down). According to the Foreign Research Reactor Spent Nuclear Fuel Acceptance Program (FRRSNF AP), about 97% of HEU from these RRs were shipped back to the United States (U.S.) since 1997. In this paper, HEU minimization effort in JAEA, including conversion of RRs, reduction of enrichment and HEU return status is described. (author)