By means of the isotopic exchange reaction between uranium dioxide powders with a normal 18O content, and carbon dioxide gas enriched in 18O, the self-diffusion of oxygen in the stoichiometric and non-stoichiometric dioxide was measured. For essentially stoichiometric UO2, the diffusion of oxygen at 550 to 780C was represented by:

D(cm2/s) = 1.2 x 103 exp[-65300/RT]

A.B.Auskern, J.Belle: Journal of Nuclear Materials, 1961, 3[3], 267-76