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

C. Berge Thierry (1) , F. Wang (1) , C. Feau (1) , I. Zentner (2) , F. Voldoire (2) , F. Lopez-Caballero (3) , A. Le Maoult (4) , M. Nicolas (4) , F. Ragueneau (5)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 EDF R&D - EDF R&D
3 MSSMat - Laboratoire de mécanique des sols, structures et matériaux
4 EMSI - Laboratoire d'Etudes de Mécanique Sismique
5 ENS Cachan - École normale supérieure - Cachan

Whatever the level of seismicity of a country, the seismic risk has to be assessed and accounted in the frame of nuclear plant safety, from its design, during its operational as well as dismantling phases. The seismic risk assessment combines the seismic hazard and the seismic vulnerability of the civil engineering and equipment estimates. Acceptable methods to perform seismic risk analyses are guided by international references, such as the Safety Guides and Requirements published by the International Atomic Energy Agency (IAEA) but also by national documents. The current methodologies used in France to assess the seismic hazard are firstly the scenario-based approach proposed in the French Fundamental Safety Rule (RFS 2001-01), and secondly the ASN/2/01 Guide providing design rules of nuclear civil engineering structures. These references were respectively updated by the Nuclear Safety Authority in 2001 and 2006. Since then, the 2011 Tohoku earthquake that triggered a huge tsunami caused the severe accident at the Fukushima Daïchi nuclear plant. The analysis of the observations demonstrated that the seismic and tsunami hazards were underestimated for this region. Consequently worldwide nuclear operators were asked by their authority to perform “stress tests” to estimate their plant 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 a multidisciplinary 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 physical phenomena (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 performed seismic risk assessment. This critical analysis conducted confronting methods, either deterministic or probabilistic, and available data to the international state of the art systematically addresses the uncertainties issue, should improve the seismic margins assessment. The present contribution will expose the first lessons learned from SINAPS@ few 18 months before its end.

Keywords: seismic risk analysis; uncertainties; seismic margin; nuclear safety

Domains: Nuclear Experiment [nucl-ex]; Nuclear Theory [nucl-th]

C. Berge Thierry, F. Wang, C. Feau, I. Zentner, F. Voldoire, et al.. The sinaps french research project first lessons of an integrated seismic risk assessment for nuclear plants safety. 16th World Conference on Earthquake - 16WCEE 2017, Jan 2017, Santiago, Chile. Paper N° 3553. ⟨cea-02438698⟩