Influence of temperature and electronic stopping power of UO 2 irradiated with swift ions on Mo migration

Abstract Molybdenum migration was studied in polycrystalline UO 2 pellets under irradiation with swift ions. 95 Mo isotope was introduced in the samples by ion implantation at a maximum concentration of 0.8 at.%. Irradiation conditions were chosen in order to understand, from a fundamental point of view, the behaviour of Mo in nuclear fuel during reactor operation. In this paper, the effect of three electronic stopping power values (7, 15 and 30 keV.nm −1 ) were investigated at different temperatures (room temperature, 600 °C and 1000 °C). The Mo concentration profiles before and after irradiation were measured by SIMS (Secondary Ion Mass Spectrometry). Raman spectroscopy was used to probe the defect creation or annealing in the UO 2 microstructure. It was evidenced that Mo is very stable in the UO 2 matrix as it migrates only for irradiation conditions combining a S e value of 15 or 30 keV.nm −1 and a temperature value of 1000 °C.