CASL Structural Mechanics Modeling of Grid-to-Rod Fretting (GTRF)

Fluid-induced grid-to-rod fretting (GTRF) wear is responsible for over 70% of fuel leaks in pressurized water reactors (PWRs) in the US. The Consortium for Advanced Simulation of Light Water Reactors (CASL) has identified GTRF as a challenge problem that is very important to nuclear plants. GTRF is a complex problem that involves multiple physical phenomena. This paper summarizes several GTRF-related problems being addressed by the University of Michigan and the Massachusetts Institute of Technology, CASL partners. These include analyses of cladding creep, wear, structural mechanics, and the effects of the rod-to-grid gap. Also outlined are additional aspects of material science and computational modeling that will be needed to realize the ultimate goal of high-fidelity predictive modeling and design tools to address GTRF.