Thermodynamics of the Zr–H binary system related to nuclear fuel sheathing and pressure tube hydriding

The thermodynamic database of the Zr–H system was updated using Density Functional Theory (DFT). In the present work, the first-principles calculations were performed using VASP (Vienna ab initio Simulation Package), which is based on pseudo-potentials and a plane wave basis set. The enthalpies of formation of ɛ-ZrH2, δ-ZrH2−x, and γ-ZrH were calculated at 0 K and it is shown that the formation of all three hydrides is spontaneous, under predicted PWR and CANDU reactor core electrochemical conditions.