Surface diffusion on UO2 was measured by the spreading of 234U tracer on the surface of a duplex diffusion couple which consisted of wafers of depleted and enriched UO2; joined by a bond of U metal. Spurious gas-phase transport was eliminated by using a masking technique. The surface diffusion coefficients, measured at 1760 to 2110C, ranged from 0.1 to 2cm2/s. The results could be described by:

D (cm2/s) = 5 x 106 exp[-72(kcal/mol)/RT]

No significant effect of the atomic weight of the inert species in the gaseous environment at 1atm pressure was detected.

S.Y.Zhou, D.R.Olander: Surface Science, 1984, 136[1], 82-102