Effect of Gd2O3 dispersion on the thermal conductivity of UO2

Abstract

10wt% Gd2O3-dispersed UO2 pellets, in which Gd2O3 particles are dispersed in UO2 matrix, were prepared, and the thermal conductivity was investigated. The Gd2O3-dispersed UO2 pellets consisted of Gd2O3, UO2, and a Gd-U-O phase that was formed by diffusion of U ions into Gd2O3 particles during the sintering process. In addition, pores were mainly distributed at the boundary between the Gd2O3 particles and the UO2 matrix. The thermal conductivity of 10wt% Gd2O3-dispersed UO 2 decreased with temperature (5.8-2.7 W m-1K-1 from 300 to 1273 K) and was larger than that of (U,Gd)O2 solid solutions (3.8-2.6Wm-1K-1) with the same Gd 2O3 content. The increase in the thermal conductivity by Gd2O3 dispersion was attributable to the reduction in phonon-point defect scattering in the UO2 matrix. Dispersion of Gd2O3 particles was effective in improving the thermal conductivity of Gd2O3-UO2 fuel pellets. © Atomic Energy Society of Japan.