Thermal conductivity measurements on 10 wt% Gd2O3 doped UO2+x

In order to evaluate the thermal conductivity of oxidized fuel pellets of leaker fuel rods, 10 wt% Gd2O3 doped UO2+x samples with x between 0 and 0.15 were prepared by the oxidation method and their thermal conductivities were estimated from their thermal diffusivity measurements. The thermal conductivity decreased with increasing hyperstoichiometry. The summation rule was valid for the phonon scattering parameter of U5+ ions and that of Gd3+ ions. The thermal conductivities of (U, Gd)O2+x pellets were evaluated as a function of their hyperstoichiometry. (orig.)