Multiphysics Modeling of the Role of Iodine in Environmentally Assisted Cracking of Zirconium via Pellet-Clad Interaction

This paper reviews the development of a multiphysics approach to studying the environmentally assisted cracking of zirconium as induced by iodine, a failure mechanism pertinent to the degradation of clad materials encasing nuclear fuel rod assemblies. The phenomenological model of Lewis is reviewed, along with atomistic modeling of surface and grain boundary effects. The paper then surveys the modeling work performed in the authors’ own research group to model the physical and chemical effects surrounding Lewis’ phenomenological model, culminating in a molecular dynamics simulation of intergranular failure. Then, recent trends in modeling are surveyed that will lead to the next steps in the multiphysics simulation of iodine-induced stress corrosion cracking of zirconium and Zircaloy materials, and potentially other systems in which intergranular corrosion cracking is a key mechanism.