THERMAL-DIFFUSIVITY OF UO2-GD2O3 PELLETS

Thermal diffusivities of UO2 and UO2-10 wt% Gd2O3 were measured over the temperature range from 298 to 2000 K by a laser flash method, paying special attention to the chemical and geometrical sample characteristics. Thermal diffusivities of UO2-10 wt% Gd2O3 were about 50% lower than those of UO2 at low temperatures, while at high temperatures the effect of Gd2O3 addition on thermal diffusivity was negligibly small. The thermal diffusivity drop at low temperatures was attributed to the large effect of phonon-point defect scattering. Thermal diffusivities of microcracked UO2-10 wt% Gd2O3 samples were about 30% lower than those of microcrack-free samples. © 1990.