A geometrical model to describe the alpha dose rates from particulates of UO2 in water

A model investigating the role of geometry on the alpha dose rate of spent nuclear fuel has been devel-oped. This novel approach utilises a new piecewise function to describe the probability of alpha escapeas a function of particulate radius, decay range within the material, and position from the surface. Thealpha dose rates were produced for particulates of radii 1μm to 10 mm, showing considerable changesin the 1μm to 50μm range. Results indicate that for decreasing particulate sizes, approaching radiiequal to or less than the range of theα-particle within the fuel, there is a significant increase in therate of energy emitted per unit mass of fuel material. The influence of geometry is more significantfor smaller radii, showing clear differences in dose rate curves below 50μm. These considerations areessential for any future accurate prediction of the dissolution rates and hydrogen gas release, drivenby the radiolytic yields of particulate spent nuclear fuel.