Geometrical aspects of alpha dose rates from UO2 based fuels

Models for calculating dose rates of spherical particles as well as in fuel cracks are important for radionuclide source term estimations. Dose rates from UO2 based fuels were calculated for planar, spherical, and crack geometries. The escape probability for α-particles in spherical UO2 particles was derived as a continuous equation. The dose rate increased with increasing spherical radius due to the decreasing relative volume of the surrounding water layer. The model produced escape probabilities that were closely predicted by the theoretical derivation. It was shown that the dose rate in water filled fuel cracks with width smaller than the range of an α-particle led to dissolution rates that were lower per unit surface area. •Alpha dose rates of spherical and crack geometries of UO2 based fuel were studied.•An expression for escape probability as function of emission depth was derived.•Dissolution rates as a function of crack width and particle radius were modelled.•Comparison with empirical treatments of the stopping power spectrum was performed.