Study on the Sintering of Gd_2O_3-UO_2 Mixed with U_3O_8 Powder

Gd2O3-UO2 is widely used as burnable absorber in nuclear power plants in recent years. It is traditionally considered that the density of Gd2O3-UO2 pellets will decrease with the adding of U3O8 powder. The original density of Gd2O3-UO2 pellets is about 94%TD in this paper. U3O8 made by incineration of AUC powder is mixed with Gd2O3 and UO2 powder, and powder mixtures with various U3O8 contents are pressed into compacts and sintered at 1750℃ in H2/H2O atmosphere. However, it is observed that the Gd2O3-UO2 pellet density increases with the adding of U3O8 powder. When the adding amount is more than 40wt% U3O8, the Gd2O3-UO2 pellet density is about 97%TD, and the U3O8 played a role as sintering additives. This phe-nomenon is contrary to the traditional knowledge that adding U3O8 will decrease the pellet density. The aver-age grain size of the pellets is about 8μm.