Alpha dose rate calculations for UO2 based materials using stopping power models

Artikel i vetenskaplig tidskrift, 2020

Accurate dose rate models for UO2 based materials in contact with water are important in the modeling of the radiolytically promoted dissolution of spent fuel. Dose rates of α-doped UO2 and un-irradiated MOX fuel were modelled using the ASTAR and SRIM stopping power databases. Dose rates were calculated as a function of distance from the active surface. Comparisons with common dose rate calculation models and the combined Bethe-Bloch and Lindhard–Scharff (LS) equation were performed. It was shown that the ASTAR and SRIM databases could more accurately simulate an α-spectrum compared to the Bethe-Bloch-LS equation. A comparison between the continuous slowing down approximation (CSDA) and the radial projection algorithm in the SRIM program was performed, and it was shown that CSDA overestimates the range of the α-particles by a few percent. This leads to an overestimation of the α-dose rate at distances close to the maximum range of the α-particle in water. A relationship between the average dose rate to specific α-activity ratio as a function of α-energy was obtained from the calculations, which can easily be implemented in alpha dose rate calculations of a UO2 based materials.