Physical properties and irradiation behavior analysis of Np- and Am-bearing MOX fuels

Kato, Masato   ; Maeda, Koji  ; Ozawa, Takayuki   ; Kashimura, Motoaki; Kihara, Yoshiyuki

Physical properties and irradiation behavior of minor actinide-bearing MOX were evaluated for the development of advanced fast reactor fuels. The physical properties of the fuels were described as functions of minor actinide content and oxygen-to-metal (/) ratio, and the effect of minor actinide addition into MOX on those properties was found to be negligibly small. The irradiation tests of fuel pellets having / ratios of 1.98 or 1.96 were carried out at high linear heat rate of about 430W/cm. The redistribution of actinide element and oxygen were analyzed by using the evaluated properties, and maximum temperatures of the pellets were estimated. The maximum temperature of the pellets of /=1.96 was estimated to reach 2680K which was 130K higher than that of /=1.98 pellets. The maximum temperature of the pellet was lower as compared with its melting temperature of higher than 3000K. In the results of post-irradiation examination, no trace of melting was observed.