Effect of Anisotropy on the Prediction of Behavior under Irradiation of a Nuclear Fuel Separator

Abstract

The Fuel Element Separator plays a crucial role in accompanying the geometric changes experienced by the Zircaloy cladding. This is particularly relevant during the various stages of fuel bundle burning, with it being essential for the separator to maintain its integrity and specific design function throughout this process to ensure burning efficiency. An elastic thermo-mechanical analysis is deemed insufficient, given the irradiation environment in which the materials are situated. This study proposes modeling a fuel cladding and separator cell in contact using 3D finite elements. Irradiation damage is described using a constitutive model based on an anisotropic viscoplastic formulation. The rate of diameter reduction of the cladding is assumed known and imposed, while a variable neutron flux is imposed. Finally, the evolution of the remaining contact force between both components and the value of the gap at end-of-life are obtained.