Assessing the safety of new nuclear fuels – Focus on degradation behaviors

•The paper addresses safety-credential assessment for new, accident-tolerant fuels.•Current guidance is specific for Zr-clad UOX fuel and may not be fully applicable.•Twelve generic in-core fuel behaviours are proposed as a safety screening tool.•Focus needs to be on degradation processes at the ‘fuel meat’–cladding–coolant level.

New nuclear fuels offering enhanced operational safety levels are being developed. A tool for qualitatively assessing their safety credentials is proposed in the form of twelve key “behavioral characteristics” at the level of the 'fuel meat'-cladding-coolant system. The assessment of safety credentials for new fuel variants should be made using guidelines that are more generic than the industry criteria for standard Zr-clad uranium oxide fuels, otherwise safety margin benefits may not be adequately recognized.