Study on factors affecting sintering density of Gd2O3-UO2 pellets

The sintered density of Gd2O3-UO2 burnable poison fuel pellets is an important quality index and is one of main QC items. Therefore, the efforts were made to investigate the factors affecting the sintered density of Gd2O3-UO2, that is, the influences of pre-treatment of Gd2O3 powder, additives, mixing methods and time, sintering atmosphere, sintering temperature and time on the final density of Gd2O3UO2 pellets contained 0, 3%, 7% and 10% (mass percentage) Gd2O3. The results show: the pre-treatment is useful for improving the distribution of Gd2O3; the additive of ammonium oxalate will effectively adjust the density of pellets; 1750 degree C is the suitable sintering temperature. The proper process parameters have been obtained, and the Gd2O3-UO2 pellets prepared for in-pile irradiation test meet the design requirements for the density (93.5%∼96.5% of T.D.), homogeneity, microstructure, etc. (8 refs., 3 figs., 8 tabs.)