A method of eliminating the surface defect in low-temperature oxidation powder added UO2 pellet

A study on methods to eliminate surface defect shown in low-temperature oxidation powder added UO2 pellet has been performed. Powders oxidized at 350 .deg. C for 4 hrs were prepared and mixed with UO2 powder after crushing them. After being sintered, surfaces of the pellet were inspected both visually and optically. A large number of defects were observed on the surface of the specimens in which low-temperature oxidation powders were directly mixed or master mixed with UO2 powder while both specimens produced from mixed powders including milled oxidation powders and powders that were milled totally after mixing had clean surfaces. However, optical examination showed considerably large defected pores in the milled oxidation powder added pellet and it was confirmed that the inner defects can be eliminated completely only when milling the entire mixture on UO2 and low-temperature oxidation powder, but not by crushing only oxidation powder