Sintering densification of CaO-UO2-Gd2O3 nuclear fuel pellets

CaO-doped UO2-10 wt% Gd2O3 burnable poison fuel was prepared by co-precipitation reaction method. It was found that 0.3 wt% CaO-doping significantly improved the sintered density, grain sizes and crushing strength of UO2-Gd2O3 fuel pellets at the sintering temperature of 1650 °C in the sintering atmosphere of hydrogen for 3.5 h. In addition, homogeneous solid solution without precipitation of free phases of CaO and Gd2O3 was successfully achieved. CaO doping in UO2-Gd2O3 fuel pellet system accelerated the thermally activated material transport, so the onset temperature of densification as well as the temperature of the maximum densification rate shifted to a lower temperature region.