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 pre-dicts that for pressure values found in the experiments, fission gas bubbles do not act as sinks for diffusing rare-gas atoms.