CATIONIC DIFFUSION AND CRYSTAL-GROWTH AT THE UO2-PUO2 INTERFACE

Interdiffusion coefficients of plutonium and uranium have been calcula ted from electron microprobe analysis of diffusion couples UO2 (green compact) / PuO2 (green compact) or UO2 (green compact) / UO2+PuO2 (gre en compact). A series of these diffusion couples was sintered at 1773, 1873 and 2023 K during 0 to 50 hours and under controlled oxygen pote ntial (-88, -95 and -125 kcal/mol). The results show that grain-bounda ry diffusion predominates in the overall diffusion process, even durin g sintering and that lattice diffusion is very slow. The sintering pro cess enhances the interdiffusion coefficients which are greater by one order of magnitude compared to those of polycrystalline diffusion cou ples.