Framework model for hydrogen redistribution in Zircaloy sheathing

Models have been developed to describe secondary hydriding phenomena. Thermodynamic models for the Zr–H and Zr–O–H systems provide the terminal solubility of dissolved hydrogen and oxygen in the α-Zr phase as a function of temperature and partial pressure. A simulation of the Sawatzky and Vogt experiment, based on a finite-element kinetic model with the thermodynamic predictions as a boundary condition, is further developed to describe the redistribution of hydrogen in a Zircaloy-2 sample placed in a temperature gradient. This analysis confirms the hydrogen diffusion coefficient.