Study of the densification of uranium-erbium system

Abstract

The sintering process of UO2-Er2O3 pellets has been investigated because of its importance in the nuclear industry and the complex behavior during sintering. The present study includes the development of nuclear fuel for power reactor in order to increase the efficiency of the fuel trough longer refueling intervals. The erbium is indicated for longer cycles, which means less stops to refueling and less waste. In this work, we studied the use of erbium oxide by varying the concentrations in the range of 1-9.8%, which was added to UO2 powder through mechanical mixing, aiming to check the rate of densification and a possible sintering blockage. The powders were pressed and sintered at 1700 C under hydrogen atmosphere. The results show a sintering blockage in the UO2-Er2O3 system that occurs in the range of 1500- 1700 C temperature. Dilatometric tests indicate a retraction of 21.9% when used Er2O3 at 1 wt. % concentration. This shrinkage is greater than is observed with higher concentrations or even without the addition of the burnable poison, providing us with a better degree of incorporation of the element erbium, resulting in pellets with density suitable for use as nuclear fuel.