Molecular dynamics study of radiation effects on tritium diffusion in zirconium tritides (δ-ZrT2-x)

Abstract

Tritium diffusivity in zirconium tritides is key to tritium storage in tritium-producing burnable absorber rods. Experiments struggle with assessing tritium diffusivity in reactor environments because irradiated defects alter diffusion. Here molecular dynamics simulations are used to investigate the irradiation effects on tritium diffusion in δ-ZrT2-x. We found that for defect-free δ-ZrT2-x, diffusivity can be described by a single Arrhenius equation for composition range x = 0.01–0.07. The irradiated vacancies slightly increase diffusivity although have no effects on diffusion energy barriers. Interestingly, irradiated self-interstitial atoms substantially increase diffusivity and reduce the energy barriers due to a lattice expansion effect.