Burn-up effect on MOX fuel thermal conductivity

Ikusawa, Yoshihisa   ; Morimoto, Kyoichi ; Maeda, Seiichiro ; Ogasawara, Masahiro*

Thermal conductivity of oxide fuel is important for fuel design and performance analyses. The thermal conductivity of oxide fuel would decrease with burn-up increase and irradiated UO fuels have been measured in various laboratories. In this study, burn-up effect on MOX fuel thermal conductivity was discussed. The influence of burn-up on the thermal conductivity of irradiated and un-irradiated MOX fuels with plutonium content of 2.54.5 wt% were evaluated by means of the thermal diffusivity measurement. The evaluated thermal conductivities showed the tendency of decrease with burn-up. Such decrease of thermal conductivity with burn-up can be explained in terms of phonon conduction model. In addition, the decrease of MOX fuel thermal conductivity would be smaller than that of UO.