Behavior of Several Rare Earth Metal Oxide Dispersions in U_O2 at High Temperature

Abstract

Several rare earth metal oxide dispersions in UO₂-Eu₂O₃, Dy₂O₃ and Sm₂O₃ were subjected to steep temperature gradient at near melting temperature of UO₂ to investigate the compatibility of rare earth metal oxides with UO₂.
The principal results obtained are as follows :
(1) Grains of massive form having a directional growth tendency were formed in the central region of the UO₂ containing the dispersions of rare earth metal oxides. No signs of columnar grain growth were observed, such as have been reported in UO₂ free of added elements.
(2) The original shapes of all three rare earth metal oxide particles were lost in the massive grain region.
(3) Various particular characteristics were observed in the microstructure of the different rare earth metal oxide-UO₂ systems.