Modeling of Cladding Failure During RIA: a new failure criteria
Research Poster Engineering 2025 Graduate ExhibitionPresentation by Katheren Nantes
Exhibition Number 164
Abstract
The increasing interest of the nuclear industry to use higher burnup fuels led different facilities to perform Reactivity-Initiated Accident (RIA) experiments on a wide range of burnup and power pulse conditions. The overall conclusion was that high burnup fuel rods could present brittle failure at deposited energies considerably lower than the current licensing criteria of 180 cal/g and 280 cal/g. This early failure can be attributed to the Zircaloy hydriding process in light water reactors and the hydrogen localization that happens during normal operation conditions, which decreases the cladding overall ductility. A thorough analysis of some failure criteria models available in the literature, showed that they are inefficient to predict hydrided cladding failure. This project presents the effort toward the development of strain-based low-temperature failure criteria for Zircaloy-4 claddings during RIA, capable of accounting for hydride rim and blister formation, besides the average hydrogen content. The new failure criteria were implemented in the nuclear fuel performance code BISON and validated against the CABRI REP-Na tests. The prediction of Pellet-Cladding Mechanical Interaction (PCMI) failure at an energy deposition within a 6.2% difference of the value reported in the experimental data proves the better accuracy of the new model.
Importance
The model developed can be used in the evaluation of the likelihood of low-temperature failures during transients, using coupled multiphysics simulations, including neutronics, thermal hydraulics, and materials behavior. Its results are validated against existing experimental data, so the model being developed is intended to improve the current licensing of nuclear power plants by providing more accurate failure criteria for high burnup fuels and be able to identify data gaps for the test reactor TREAT.