Finite element study of pressure-assisted diffusion of hydrogen in deformed zirconium polycrystals

Zirconium alloys, due to their high hardness, ductility and corrosion resistance, are commonly used as cladding for fuel rods in nuclear reactors, especially water reactors. Oxidative reaction of zirconium with water releases hydrogen gas, leading to brittle zirconium hydrides as a result of low hydrogen solubility and local concentration gradients. These brittle precipitates have a detrimental effect on the mechanical properties of the cladding, decided by various microstructural features. In this study, results from 3-dimensional finite element simulations of pressure-assisted diffusion of hydrogen in elastically deformed zirconium polycrystals are presented. Simulations are performed on digital microstructures and the variation of local hydrogen concentration with crystallographic texture, grain size and shape are depicted. Simulation results are validated with experimentally available results, where possible. (author)