Computer simulation of hydrogen ingress and oxidation kinetics on ZR-NB pressure tubes

The oxide film which formed on the Zr-2.5% Nb pressure tube surface serves as a protective barrier against hydrogen ingress. Hydrogen ingress is a diffusion process and therefore is affected by oxide orientation, grain size, grain shape, and grain boundary distributions. Our earlier research has focused on understanding the oxidation mechanism and predicting the oxide texture and microstructure development. In this paper, we will demonstrate how to simulate the hydrogen ingress and oxidation kinetics by using the information obtained on the oxide texture and microstructure. The effects of the oxide and substrate texture, grain size, grain shape, and a phase distribution on hydrogen permeation and oxidation kinetics can be simulated. The program is designed for optimizing the resistance of the Zr tube against hydrogen permeation and oxidation. (author)