Oxidation and hydrogen uptake in zirconium, Zircaloy-2 and Zircaloy-4: Computational thermodynamics and ab initio calculations

The “checker board” configuration for O atoms in octahedral interstitials. Zr atoms are shown in cyan, O in the first layer - in red, O in the second layer - in pink. Four non-equivalent groups of interstitials are indicated by numbers and yellow arrows. The formation of such “suboxide” ordered atomic structures was shown to slow down the uptake of hydrogen by different zirconium nuclear components.