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Abstract

There is provided a method of producing UOpowder having large surface area and small particle size by oxidizing defective UOpellets and manufacturing nuclear fuel pellets which are stable in a pore structure and high in density through the use of a mixture comprising UOpowder and UOpowder. The method includes producing an U308 powder having a surface area of at least 1 m/g by oxidizing defective UOpellets at a temperature of 300 to 370° C. in such a way that a maximum weight increase rate per 1 g of the UOpellets is up to 0.06 wt %/min; producing a mixed powder by mixing the UOpowder with an UOpowder by 2 to 15 wt %; producing a compact by compression molding the mixed powder; and sintering the compact in a reducing gas atmosphere at a temperature of 1600 to 1800° C. In addition, a small amount of an Al-compound may be added to the oxidized UOpowder before the UOpowder is mixed with the UOpowder. The additive such as Al is mixed with the UOpowder and then mixed with the UOpowder to produce the pellets by a conventional production method. This ensures a stable pore structure, high density and a considerable increase in a crystal grain size.