Effects Of Adding U_RO_X Powder On Compacting And Sintering Performance In Pellet Manufacture Technology Using IDR Process UO₂

The surface quality of UO₂ pellet considerably affects its safety operation in a nuclear reactor .Various types of surface defects may occur in ceramic UO₂ pellet production, which can be avoided by adjusting and controlling process parameters.Aiming at the poor mouldability of IDR (The Integrated Dry Route) process UO₂ powder and the evident surface defects of the pellets manufactured by the UO₂ powder, U₃O₈ and U_RO_X powders were added to the UO₂ powder, which improved the agglomerate state of the UO₂ particles, reduced the mean density of the blepharoplast and sintered pellets and increased wearability. The chemical physical performance and surface quality of the pellets thus obtained met the specification of fuel UO₂ pellets.U₃O₈ powder used was prepared by oxidation of the waste pellets and grinding scrap from production process. In present paper preparation of U_RO_X powder from IDR process UO₂ powder was studied. Effects of oxidation temperature and oxidation duration on U_RO_X powder performance such as O/U ratio and specific surface area were investigated. These U_RO_X powder was added to the UO₂ powder and compacted, the wearability of the blepharoplast thus obtained was examined. Optimal oxidation temperature and time were determined to be 350℃and 5 hours, respectively.Effects of U_RO_X addition dosage on green density, green wearability and sintering density were investigated at a fixed U₃O₈ addition dosage. A optimal U_RO_X addition dosage was determined.The improvement of UO₂ powder compactibility is probably related to a variation of the powder size distribution, which makes the density distribution in the blepharoplast more homogeneous and reduces spring back. The experimental and batches productional statistics results show that by addition proper amounts of U₃O₈ and (or) U_RO_X powders the surface quality of UO₂ pellets meets the specification. There are no defects such as surface big crack and capping. The rejection of pellets due to surface defects was basically avoided.