Oxygen diffusion in UO2 single crystal and polycrystal

Oxygen diffusion has been measured in UO2 single crystal and polycrystal. The experiments were performed using the isotope exchange method. The diffusion profiles were measured by secondary ion mass spectrometry (SIMS). Between 605 deg C and 750 deg C, the diffusion coefficients obtained in single crystals and polycrystals were similar and ranged from 7.90 x 10-4 to 3.60 x 10-12 for the single crystals and between 8.90 x 10-14 and 2.30 x 10-12 cm2/s for the polycrystals. Our results show that there is no preferential oxygen diffusion in the grain boundaries of UO2. (author)