Enthalpy measurement and evaluation of heat capacity on (U, Pu)O in high temperature region

Morimoto, Kyoichi ; Ogasawara, Masahiro*

The heat capacity of MOX fuel is one of important thermophysical properties for the evaluation of its thermal conductivity and for the evaluations of transient event and severe accident of nuclear reactor. In this study, MOX sample with Pu-content of nearly 50% (50%Pu-MOX) was measured because it was predicted that the influence of Pu addition appeared to be significant. The raw material powder was cold-pressed and was sintered to make pellet. The oxygen to metal ratio of this pellet was adjusted to 2.00. The enthalpy of this sample was measured with drop calorimeter in high temperature range. The rhenium container was used to prevent the reaction between the sample and the sample container. It was found that the enthalpy increased at a nearly constant rate up to about 1900K with increasing temperature and that its rate rose at about 1900K or more. It means that the heat capacity is approximately constant up to 1900K and starts to rise at about 1900K.