Experimental evaluation of the high temperature thermophysical properties of UO₂

High temperature properties of UO₂ are reported, in particular thermal conductivity, specific heat capacity, thermal diffusivity and melting point. All are measured with a single laser flash apparatus coupled with a numerical inverse method. The thermal conductivity, spectral emissivity, specific heat capacity, thermal diffusivity and melting point are in very good agreement with established literature values indicating the validity of the methodology and its potential for measuring these properties up to melting. The melting point was identified to be 3118 K ± 28 K. The thermal conductivity exhibits a minimum between 1800 K and 2100 K due to the competition between phonon scattering and an increase in the concentration of free charge carriers. The substantial increase in specific heat can be predominantly attributed to the formation of oxygen Frenkel pairs.