Thermal Conductivity of UO2–BeO–Gd2O3 Nuclear Fuel Pellets

In the present paper, the influence of the beryllium oxide addition to increase the thermal conductivity in uranium dioxide fuel pellets containing gadolinium oxide as burnable poison was investigated. Fuel pellets of UO2, UO2–BeO–Gd2O3, and UO2–Gd2O3 were obtained in concentrations of 2–3 wt % of BeO and 6 wt % of Gd2O3. The thermal diffusivity was determined at room temperature and until 773 K by Laser Flash and Thermal Quadrupole methods, respectively. The thermal diffusivity and thermal conductivity were normalized to 95 % TD (theoretical density). The maximum relative expanded uncertainties of the thermal diffusivity and thermal conductivity measurements were estimated to be 7.5 % and 8.0 %, respectively. In addition, the obtained results were compared with the theoretical models and experimental data given in the literature. The results showed an increase in the thermal diffusivity and conductivity of the UO2 pellets with additions of BeO as compared to the values obtained with UO2 and UO2–Gd2O3 pellets.