Effect of grain-boundaries on uranium and oxygen diffusion in polycrystalline UO2.

Abstract

The influence of grain-boundaries on uranium and oxygen difusion in polycrystalline UO2 has been investigated. Our results show that between 1498°C and 1697°C, in H2 atmosphere, uranium difusion in UO2 grain-boundaries is about ®ve orders of magnitude greater than uranium volume di€usion, in the same experimental conditions. Between 605°C and 750°C, in H2/N2/H2O atmosphere, the oxygen difusion coe cients measured in polycrystalline and single crystalline UO2 are similar, and correspond to the volume difusion.