A study of xenon aggregates in uranium dioxide using X-ray absorption spectroscopy

X-ray absorption spectroscopy experiments were performed on a set of xenon implanted uranium dioxide samples. Results indicate that the gas forms highly pressurised inclusions as a result of temperature anneals or an external ion irradiation. Estimated bubble pressures were found to be in the region of 2–5 GPa at low temperature. The consequences of such high pressures developing within intra-granular bubbles in irradiated fuels are discussed. A model is given enabling the computation of the sink strengths of bubbles as a function of the pressure of the rare-gas they contain. The model predicts that for pressure values found in the experiments, fission gas bubbles do not act as sinks for diffusing rare-gas atoms.