New fabrication process of large grain pellet for LWR

'Oxidation-sintering pellets' and 'Al2O3/SiO2 additive pellets' were developed. Both pellets will be used for high burnup due to their good FGR and PCI properties. In the 'oxidation-reduction sintering process', U3O8 powder is added to UO2 powder as a source of oxygen to produce U4O9 and to get large grain pellets. Atmosphere of the oxidation sintering process is O2+N2 and the sintering temperatures for both the oxidation and the reduction processes are relatively low compared with that for the standard sintering process. In Al2O3/SiO2 addition, Al2O3/SiO2 covers UO2 grain and enhances its grain growth. Contents of Al2O3 and SiO2 are very low (∼50,50 PPM), therefore there is little impact on a reprocessing process. Both type of pellets are under irradiation in test reactors and a commercial reactor as demonstration fuels. We will choose one type of pellet after PIE, and will use it for high burnup (55 GWd/t) as commercial fuels. (author)