Analysing hydrogen behaviour in liner claddings using OFFBEAT fuel performance code

• Hydrogen behaviour models have been implemented in OFFBEAT. • Models for hydrogen solubility in liner claddings implemented. • Validation study against out-of-pile experiments has been conducted. • The simulated results are in good agreement with experiments and Falcon code. Hydrogen generated during the waterside corrosion of zirconium claddings can diffuse within the material, forming hydrides that alter the mechanical properties of the claddings. These hydrides may lead to detrimental effects such as delayed hydride cracking and embrittlement, compromising the integrity of the claddings. Liner claddings, which have been particularly used in Swiss reactors, have been shown to aid in minimizing these detrimental effects of hydrogen behaviour on zirconium claddings. In this paper, hydrogen behaviour models for liner claddings have been incorporated into the multi-dimensional, thermo-mechanical fuel performance code, OFFBEAT. Numerical analyses using OFFBEAT are then compared to out-of-pile experimental data on two liner cladding types commonly used in Swiss reactors. The findings indicate that OFFBEAT’s predictions closely align with experimental observations, demonstrating hydrogen migration toward the substrate-liner interface (SLI). This research confirms OFFBEAT’s capability to simulate hydrogen behavior in liner claddings, supporting further exploration of alternative cladding configurations moving forward towards more advanced technological fuels for nuclear safety.