Recently it has been suggested that dislocations, generated by radiation
damage, may increase the rate of fission gas diffusion from the fuel grains,
an affect which is at present not incorporated into fuel performance codes.
Therefore, we perform molecular dynamics simulations employing empirical
potentials to investigate the diffusion of Xe atoms around edge dislocations
in UO2 to establish the importance of this pathway for fission gas release.
The results suggest that for isolated atoms near the dislocation the activation
energy for Xe diffusion is dramatically reduced relative to the bulk. However,
Xe atoms diffusing along the dislocation cluster together to form small bubbles,
these bubbles incorporate all of the isolated mobile Xe atoms thereby
inhibiting fast diffusion of Xe along the dislocation core.