Diffusion couples with polycrystalline urania and Am-MOX discs were annealed for 4.5 h at 1600C under constant oxygen partial pressures. Concentrations of Pu and Am across the interfaces of the couples were measured using electron probe micro-analysis. The average diffusion coefficients of Pu and Am were estimated to be 10−15 and 10−14 m2/s by fitting their concentration profiles to Fick's law, and the difference between them was not significant. Grain boundary diffusion made the largest contribution to the diffusion coefficients. From the analysis of the diffusion depth based on a diffusion type classification, lattice diffusion coefficients were expected to be less than 10−17m2/s at 1600C.

Diffusion Behaviors of Plutonium and Americium in Polycrystalline Urania. I.Sato, K.Tanaka, T.Arima: IOP Conference Series - Materials Science and Engineering, 2010, 9[1], 012005