Diffusion of fission product tritium in irradiated UO2

The effect of temperature on the rate of release of tritium from neutron-irradiated polycrystalline and single-crystal UO2 has been studied. The diffusion coefficients for tritium from 500-10000C are found to be several orders of magnitude lower than those reported for molecular hydrogen in U02 single crystals. Fractional release curves are indicative of classical diffusion and the Arrhenius plots for both polycrystalline and single crystal materials can be fitted by the diffusion equation: D = 0.12 (+0.21 - 0.07) X exp(-43 600 +- 1800 cal/RT)cm2/s. (Auth.)