Seismic Hazard Assessment for French Nuclear Facilities: Current Practices and Future Research Needs

Maria Lancieri (introduction: A. Walpersdorf) - IRSN - Institut de radioprotection et de sûreté nucléaire
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Seismic Hazard Assessment for French Nuclear Facilities: Current Practices and Future Research Needs Seismic hazard assessment for French nuclear facilities (NFs) is currently based on the 2001 nuclear code (RFS 2001-01), which prescribes a deterministic seismic hazard analysis (DSHA) approach. The goal is to determine the expected ground motion at a given NF by considering the maximum plausible historical earthquake(s) in the seismotectonic zones surrounding the facility. This requires a deep understanding of the geology and seismic activity of these sources, which can be particularly challenging in a low to moderate seismic region like mainland France. Two decades after the publication of this regulatory framework, an update appears necessary. In the initial stage, a critical review of the existing RFS is needed to identify elements worth retaining and those requiring significant revision, while also incorporating lessons learned from recent seismic events in mainland France, such as the Le Teil earthquake. Additionally, it is essential to strike the right balance between the advances in the state of the art in every step of the hazard assessment methods and ensuring compatibility with industrial and operational constraints. To address these challenges, the Institut de Radioprotection et de Sûreté Nucléaire (IRSN) is engaged in research programs aimed at gathering geological and geophysical data, as well as developing new methods—or improving the existing ones—for hazard assessments. These research efforts are conducted alongside the review of safety reports submitted by nuclear operators to the regulatory authorities, placing IRSN at the intersection of academic research and regulatory decision-making in the field of nuclear safety. In this seminar, I will introduce the fundamental principles of French nuclear safety. I will then provide an overview of current seismic hazard assessment practices for nuclear power plants, highlighting the stages that require discussion or revision. The seminar will conclude with an examination of unresolved technical and scientific questions, emphasizing the role of academic research in supporting future regulatory code updates.