Diffusion coefficient measurements of U4+ in stoichiometric UO2 were performed by using the surface activity decrease method. Uranium diffusion at 1450 to 1785C was represented by:

D(cm2/s) = 4.3 x 10-4 exp[-88000/RT]

A.B.Auskern, J.Belle: Journal of Nuclear Materials, 1961, 3[3], 311-9