The sinaps french research project first lessons of an integrated seismic risk assessment for nuclear plants safety

International audienceWhatever the level of seismicity of a country, the seismic risk has to be assessed and accounted in the frame ofnuclear plant safety, from its design, during its operational as well as dismantling phases. The seismic risk assessmentcombines the seismic hazard and the seismic vulnerability of the civil engineering and equipment estimates. Acceptablemethods to perform seismic risk analyses are guided by international references, such as the Safety Guides andRequirements published by the International Atomic Energy Agency (IAEA) but also by national documents. The currentmethodologies used in France to assess the seismic hazard are firstly the scenario-based approach proposed in the FrenchFundamental Safety Rule (RFS 2001-01), and secondly the ASN/2/01 Guide providing design rules of nuclear civilengineering structures. These references were respectively updated by the Nuclear Safety Authority in 2001 and 2006. Sincethen, the 2011 Tohoku earthquake that triggered a huge tsunami caused the severe accident at the Fukushima Daïchi nuclearplant. The analysis of the observations demonstrated that the seismic and tsunami hazards were underestimated for thisregion. Consequently worldwide nuclear operators were asked by their authority to perform “stress tests” to estimate theirplant capacity sustaining extreme seismic loadings. In this framework, an 5 years research project called SINAPS@(Earthquake and Nuclear Installations: Ensuring and Sustaining Safety) is on-going in France. SINAPS@ brings together amultidisciplinary community of researchers and engineers, funding also 12 Ph.D. and 19 post-doctoral researchers.SINAPS@ aims at conducting a continuous analysis of completeness and gaps in data bases (all data types, from geology,seismology, site characterization and materials), of the reliability or deficiency of models available to describe physicalphenomena (prediction of seismic motion, site effects, soil and structure interaction, linear and nonlinear wave propagation,materials constitutive laws in nonlinear domain), and of the relevance or weakness of methodologies used to performedseismic risk assessment. This critical analysis conducted confronting methods, either deterministic or probabilistic, andavailable data to the international state of the art systematically addresses the uncertainties issue, should improve theseismic margins assessment. The present contribution will expose the first lessons learned from SINAPS@ few 18 monthsbefore its end