Arent Fox Kintner Plotkin & Kahn, PLLC
Method of manufacturing large-grained uranium dioxide fuel pellets containing U3O8
 Disclosed is a method of manufacturing large-grained uranium dioxide pellets through the use of U.sub.3 O.sub.8 single crystals. The method consists of two main steps; producing U.sub.3 O.sub.8 single crystals and manufacturing large-grained UO.sub.2 pellets. The U.sub.3 O.sub.8 single crystals are produced by annealing U.sub.3 O.sub.8 powder to make U.sub.3 O.sub.8 polycrystalline aggregates having a large crystal size, and by dividing the U.sub.3 O.sub.8 polycrystalline aggregate into its constituent U.sub.3 O.sub.8 single crystals. Large-grained UO.sub.2 pellets are produced by forming a mixture comprising UO.sub.2 powder and the U.sub.3 O.sub.8 single crystals, making granules of the mixture, pressing the granules into green pellets, and sintering the green pellets above 1600.degree. C. for more than one hour in a reducing gas. The U.sub.3 O.sub.8 powder is produced preferably by heating defective UO.sub.2 pellets in air to oxidize UO.sub.2 to U.sub.3 O.sub.8. The invention provides a method of manufacturing a large-grained UO.sub.2 pellet with defective pellets reused. 
Korea Atomic Energy Research Institute Korea Electric Power Corporation
G Y G
G21C Y02E G21C
inventional additional inventional
Keon-Sik Youn-Ho Jong-Hun Kun-Woo Ki-Won
Kim Jung Kim Song Kang