PRODUCTION METHOD COMPRISING CONVERTING URANIUM ALLOY TO UO2 POWDER AND PELLET

PROBLEM TO BE SOLVED: To provide a method for producing high-quality UO2 powder through such a process that an acid solution containing metallic impurities and uranium oxide formed by oxidizing uranium-contg. alloy powder at high temperatures is subjected to solvent extraction to afford ammonium diuranate which is then heated. SOLUTION: This method for producing UO2 powder comprises the following steps: uranium-contg. alloy powder ground by a jaw crusher is oxidized in a furnace at 350-550 deg.C and converted to an alloy comprising U3O8 and metallic impurities, the alloy is then dissolved in nitric acid to form a uranyl nitrate slurry, which is then refined through filtration and/or solvent extraction to form an acid solution containing uranyl nitrate and the resultant solid waste and liquid waste are removed; subsequently, ammonium hydroxide as precipitant is added to the above acid solution to precipitate ammonium diuranate which, in turn, is separated from the mixture by centrifugal separation and then reduced by calcination in the presence of hydrogen into uranium dioxide (UO2); the uranium dioxide powder thus obtained is subjected to mill grinding, slag conversion and granulation followed by pressing, sintering and polishing to produce pellets, which are then packed into fuel rods.