Direct alpha spectrometry for analysing leached ThO2 pellets

Abstract The next generation application of nuclear energy has shown an interest towards ThO 2 or mixed oxides fuels. However, more knowledge is needed, for example, on the microstructural and matrix dissolution behaviour of ThO 2 . The objective of this study was to examine surface properties of thick ThO 2 pellets by non-destructive alpha analysis method accompanied with Monte Carlo simulations before and after a leaching experiment. This study has been conducted to investigate the contents, and surface layer thickness of crystalline 232 ThO 2 pellet leached in aqueous solution with excess of 229 Th tracer in the beginning of the experiment. The simulation results have suggested a maximum 0.1 μm concentrated layer of 229 Th on the pellet surface. The presence of this layer suppresses further dissolution of the pellet.