The potential to use fission gas release experiments to measure lattice and grain boundary diffusion in metallic fuels

We have applied a model for lattice and grain boundary diffusion in polycrystalline materials to assess the potential for the use of fission gas release experiments to measure the lattice and grain boundary diffusion coefficients in metallic nuclear fuel materials. Our assessment is that, assuming that grain boundary diffusion in metallic fuels is similar to that in other metals, it is reasonable to expect that lattice diffusion coefficients can be determined from short time gas release experiments and the product of the grain boundary diffusion coefficient, the segregation factor, and the boundary width can be extracted from gas release experiments at longer times. Under the same assumption, activation energies can be deduced from the temperature dependence of the measured diffusivities.