Study On MOX Fuel Pellets Sintering Process And Device

The development of MOX (Mixed OXide) nuclear fuel,composed of UO2 and PuO2,can improve natural uranium utilization, lessen negative effects on nuclear power development in China resulting from the uranium resource shortage and the continue rising in uranium, reduce plutonium reserve to decrease the risk of nuclear proliferation, and ensure nuclear and environment safety. It plays an important role in promoting the large-scale, long-term , and sustainable development of nuclear power in China.Pressing and sintering of MOX pellets is the critical part in the process of MOX nuclear fuel production. Therefore the study on the MOX pellets sintering process and device has extensive application prospect.Considering inconvenience of MOX fuel preparation caused by the radioactivity and toxicity of plutonium, it is reasonable to use cerium,which has similar thermodynamic properties to Pu, to simulate Pu. The simulated MOX (UO2-x%CeO2) nuclear fuel pellet is prepared by blending, pressing and high temperature sintering. It shows that the simulated MOX (U-Ce-O) nuclear fuel pellet can meet the technical requirements. In this paper, we study on the key production equipment of MOX pellets. The use characteristics of ball mill,granulating machine,molding press and sintering furnace are studied respectively.MOX powder properties, pressing conditions and sintering characteristics are also studied. The results show that a favorable powder properties such as blending homogeneity,specific surface-area and grain size particle size distribution , can be obtained by optimizing milling parameters: hydrous ethanol blending/ dry blending; ball milling speed 300r·min-1;the ratio of ball/ raw materia 15:1 (g/g); the ratio of raw material/ mixing medium 5:2;milling time 2-4h. MOX pellet prepared under the condition of 400MPa (pressing force),1750?/4h (sintering temperature/ holding time), has high density (up to p>95%TD), fine grain size, homogenous microstructure, and appropriate open and close porosity. Finally, the O/M of the sintered MOX pellets is measured under different process conditions.Considering the reasonable errors, the results meet the technology standards.