Development and demonstration of ATR-MOX fuel

Japan Nuclear Cycle Development Institute (JNC) has developed plutonium and uranium mixed oxide (MOX) fuels for an advanced thermal reactor (ATR) to provide a flexible utilization of plutonium. JNC endeavored to obtain well-homogenized MOX pellets by a ball mill mixing method with a variety of raw powders; one of these powders included MOX powder prepared by a microwave-heating denitration process. A total of 772 MOX fuel assemblies were utilized in the ATR prototype reactor 'FUGEN' with no failures throughout its entire operation period. The adequacy of the fuel fabrication system, including fuel design and quality control, was demonstrated by theses remarkable irradiation results. JNC also developed an advanced MOX fuel assembly for a demonstration ATR. The integrity of the advanced fuel assembly under in-core conditions was proven by various irradiation experiments. The demonstration ATR was unfortunately canceled as part of governmental economy measures, but extensive irradiation data of MOX fuels have contributed to develop LWR-MOX fuels. (authors)