Development of rock type plutonium fuel and its combustion treatment technology

At present, in Japanese nuclear fuel cycle, plutonium is made by the planned production, and is to be used as the fuel for LWRs and FBRs, therefore, the transparency of utilization is very high. However as reported by IAEA, 120 - 200 t of the separated plutonium of LWR class, the utilization of which is unclear, accumulates by the beginning of 21st century. Moreover, about 100 t of high purity Pu-239 is taken out by the disassembling of strategic nuclear weapons. In Japan Atomic Energy Research Institute, the basic research on the plutonium combustion system using rock type Pu fuel and LWRs was started in 1994. As to the concept of the plutonium combustion treatment system, rock type fuel and its combustion characteristics are described. The research plan is shown. In first period, basic research, in second period, engineering research, and in third period, actual operation and improvement are planned. The present state of the basic research in the first period is reported on the research of fuel development, the research of combustion technology, the improvement of Doppler coefficient and the amount of plutonium combustion treatment. (K.I.)