Thermal conductivity measurement of (Pu_1-xAm_x)O₂ (x = 0.028, 0.072)

The thermal diffusivity of (Pu,Am)O₂ was measured by the laser flash method in the temperature range from 750 K to 1450 K, and the thermal conductivity was estimated from the measured thermal diffusivity, the bulk density and the heat capacity obtained from the Kopp-Neumann rule. In the measurements up to 1250 K, the O/M ratio of the specimens was kept almost constant at 2, and it could be concluded that the thermal conductivity of stoichiometric (Pu,Am)O₂ with a small Am content was insensitive to Am content. However, the O/M ratio of the specimen with 7.2 mol% Am content might be reduced at high temperatures, and it might lead to a small decrease in thermal conductivity. These Am content dependences of thermal conductivity were well explained by the phonon scattering model for thermal resistivity.