Thermal conductivity of UO2 and U3O8 (JNM)

P. B. Weisensee, J. P. Feser, D. G. Cahill, “Effect of ion irradiation on the thermal conductivity of UO2 and U3O8 epitaxial layers“, J. Nucl. Mat. 443 (2013) 212-217

The effect of 2 MeV Ar+-ion irradiation on the thermal conductivity of epitaxial layers of UO2 and U3O8 was studied with time-domain thermoreflectance (TDTR) at temperatures between 323 and 658 K. The thermal conductivity of unirradiated UO2 is 10.2 W/m.K at 323 K and scales with temperature like 1/T. Upon irradiation with doses >0.7 x10^15 Ar+ cm², the thermal conductivity decreases to a nearly constant value <4 W/m.K. By comparing the data to an analytic model, we report the point-scattering strength of irradiation induced defects in UO2. Unirradiated U3O8 has a thermal conductivity of 1.6 W/m.K at 333 K. Low and medium doses of Ar-ion irradiation decrease the thermal conductivity of U3O8 to <1.0 W/m.K. Unexpectedly, it is found that higher doses of Ar+ irradiation increased the conductivity of U3O8 to 2.0 W/m.K.