Modeling of Zircaloy Oxidation Through Dynamic Mesh Deformation

Abstract

Zircaloy cladding corrosion in Light Water Reactors (LWRs) results in the formation of an outer oxide layer and in the thinning of the metallic portion of the cladding. At the École Polytechnique Fédérale de Lausanne (EPFL), we aim to investigate the impact of asymmetric oxide or crud layers and their feedback on thermal-hydraulics. To achieve this, we are implementing mechanistic capabilities for the treatment of corrosion within the open-source multi-dimensional code OFFBEAT. In this work, we outline our approach based on the combination of traditional laws for predicting the growth of the oxide layer with methods to dynamically modify the mesh points and topology. Specifically, our methodology employs routines available in the OpenFOAM library to add or remove layers of cells according to the growth of the oxide layer, along with a mesh motion solver to maintain mesh quality. We verify the methodologys against an analytical test case and then we demonstrate its potential for the study of non-uniform oxide distributions by modeling a simplified cladding ring with asymmetric temperature profile, mimicking the conditions of azimuthal power peaking in a Boiling Water Reactor (BWR).