Development and validation of models for fuel rod oxidation and hydrogen pick-up behaviors in pressurized water reactor

BackgroundDuring the long-term operation of a nuclear reactor, the contact between zirconium alloy cladding and cooling water results in oxidation reactions and hydrogen uptake-induced embrittlement behavior, which deteriorates the thermal and mechanical properties of the cladding, posing a threat to the safety characteristics of fuel elements. Therefore, conducting research on the oxidation and hydrogen uptake behavior of rod-shaped fuels is of significant importance. MOOSE is an object-oriented finite element multi-physics coupling platform developed using the C++ programming language. BEEs, developed based on MOOSE, is programmed in C++ and operates under the Linux system.PurposeThis study aims to integrate a corrosion model into MOOSE-BEEs fuel performance code and verify its adaptability, consisting of an oxidation corrosion model and a hydrogen absorption corrosion model.MethodsFirstly, a corrosion calculation model for pressurized water reactor rod-shaped fuel in the MOOSE-BEEs program was developed and integrated into the MOOSE platform to enhance the functionality of the BEEs program. The corrosion model primarily included an oxidation corrosion model and a hydrogen absorption corrosion model. The oxidation model served as the boundary of the hydrogen absorption model to provide hydrogen uptake. The hydrogen at the boundary diffused under the action of concentration gradient and temperature gradient. Then, according to the relationship between the concentration in the region and the terminal solid solubility, predictions was made regarding the occurrence of precipitation phenomena at this location. The terminal solid solubility and precipitation rate are related to temperature. Subsequently, simple geometric structures were established to perform coupled calculations of fuel thermal conductivity, oxidation, hydrogen absorption corrosion, hydrogen diffusion and precipitation. Finally, the calculated results were compared with the BISON program and experimental values, and the hydrogen precipitation was verified in terms of terminal solid solubility and precipitation rate.ResultsBased on experimental data and computational results from the BISON program, separate models and coupled models for oxidation corrosion, hydrogen diffusion and hydrogen precipitation have been validated. The oxidation corrosion model is in good agreement with REP Na10 experiment results and Katheren calculation results. Hydrogen diffusion verification includes concentration gradient verification and temperature gradient verification. The diffusion model and hydrogen precipitation model are in good agreement with the results of BISON simulation and Kammenzind experiment. The coupling model of oxidation and hydrogen absorption corrosion is in good agreement with the results of BISON simulation and Gravelines reactor experiment. The difference between the calculated results of most corrosion models and the experimental values and BISON program is less than 10%.ConclusionsThe validation results demonstrate that the BEEs predictions are in good agreement with the experimental data and BISON program, indicating that BEEs is capable of accurately simulating the oxidation and hydrogen absorption behavior of fuel rods.