GRAIN-GROWTH AND OSTWALD RIPENING IN CHROMIA-DOPED URANIUM-DIOXIDE

The use of solid solution additives such as ''corundum'' types oxides is a practical mean for enhancing grain growth of stoichiometric urani um dioxide. The present paper deals with chromia-doped UO2 samples. La rge-grain sized fuels can be produce by addition of less than 1000 ppm of chromia to UO2 powder prior to sintering. Above the solubility lim it, excess of insoluble Cr2O3 precipitates from solid solution to crea te second phase inclusions in UO2 matrix. These inclusions coalesce by an Ostwald ripening phenomenon.