Grain-boundary diffusion in uranium dioxide: The correlation between sintering and creep and a reinterpretation of creep mechanism

Abstract Previously published data on the final stage sintering kinetics of stoichiometric uranium dioxide are correlated with a reinterpretation of low-stress creep behaviour of identical material (data on both processes by the present authors). For both processes the rate-controlling diffusional flux is considered to be that of uranium ions along grain boundaries. The effective diffusion coefficient for uranium ion diffusion along grain boundaries, D GB , is estimated to be: D GB = 1.38( ÷ x 5) × 10 −6 exp − [(2.39 ± 0.8) × 10 5 /8.31T] m 2 /s . Comparisons are made between this value and those previously measured by radio-tracer methods.