Review of fuel safety criteria in France

Fuel safety criteria for the first barrier, based on state-of-the-art at the time, were first defined in the 1970s and came from the United States, when the French nuclear program was initiated. Since then, there has been continuous progress in knowledge and in collecting experimental results thanks to the experiments carried out by utilities and research institutes, to the operating experience, as well as to the generic R and D programs, which aim notably at improving computation methodologies, especially in Reactivity-Initiated accident and Loss-of-Coolant Accident conditions. In this context, the French utility EDF proposed new fuel safety criteria, or reviewed and completed existing safety demonstration covering the normal operating, incidental and accidental conditions of Pressurised Water Reactors. IRSN assessed EDF's proposals and presented its conclusions to the Advisory Committee for Reactors Safety of the Nuclear Safety Authority in June 2017. This review focused on the relevance of historical limit values or parameters of fuel safety criteria and their adequacy with the state-of-the-art concerning fuel physical phenomena (e.g. Pellet-Cladding Mechanical Interaction in incidental conditions, clad embrittlement due to high temperature oxidation in accidental conditions, clad ballooning and burst during boiling crisis and fuel melting).