Main Achievements of the Multidisciplinary SINAPS@ Research Project: Towards an Integrated Approach to Perform Seismic Safety Analysis of Nuclear Facilities

Abstract

This contribution provides an overview of the SINAPS@ French research project and its main achievements. SINAPS@ stands for ''Earthquake and Nuclear Facility: Improving and Sustaining Safety'', and it has gathered the broad research community together to propose an innovative seismic safety analysis for nuclear facilities. This five-year project was funded by the French government after the 2011 Japanese Tohoku large earthquake and associated tsunami that caused a major accident at the Fukushima Daïchi nuclear power plant. Soon after this disaster, the international community involved in nuclear safety questioned the current methodologies used to define and to account for seismic loadings for nuclear facilities during the design and periodic assessment review phases. Within this framework, worldwide nuclear authorities asked nuclear licensees to perform 'stress tests' to estimate the capacity of their existing facilities for sustaining extreme seismic motions. As an introduction, the French nuclear regulatory framework is presented here, to emphasize the key issues and the scientific challenges. An analysis of the current French practices and the need to better assess the seismic margin of nuclear facilities contributed to the shaping of the scientific roadmap of SINAPS@. SINAPS@ was aimed at conducting a continuous analysis of completeness and gaps in databases (for all data types, including geology, seismology, site characterization, materials), of reliability or deficiency of models available to describe physical phenomena (i.e., prediction of seismic motion, site effects, soil and structure interactions, linear and nonlinear wave propagation, material constitutive laws in the nonlinear domain for structural analysis), and of the relevance or weakness of methodologies used for seismic safety assessment. This critical analysis that confronts the methods (either deterministic or probabilistic) and the available data in terms of the international state of the art systematically addresses the uncertainty issues. We present the key results achieved in SINAPS@ at each step of the full seismic analysis, with a focus on uncertainty identification, quantification, and propagation. The main lessons learned from SINAPS@ are highlighted. SINAPS@ promotes an innovative integrated approach that is consistent with Guidelines #22, as recently published by the French Nuclear Safety Authority (Guidelines ASN #22 2017), and opens the perspectives to improve current French practice.

SEM3D: A 3D High-Fidelity Numerical Earthquake Simulator for Broadband (0–10 Hz) Seismic Response Prediction at a Regional Scale

“…This explains the fact that the PSA predicted by F5 and O2 simulations at those locations are the same. Such control points were introduced, as suggested by Berge-Thierry et al [105], in order to check that the regional ground motion model was not affected by the change in mechanical properties within the basin and that the incident wave-field remained unchanged from one simulation to another. The large dispersion in Figure 12 may be essentially linked to two major aspects: (1) the directivity effects engendered by this particular realization of the source scenario and (2) the arbitrary slip patch adopted for the blind prediction.…”

A New Generation of Earthquake Recurrence Models Based on The Extreme Value Theory and Impact on Probabilistic Seismic Hazard Assessments

“…To elaborate the Random Gutenberg-Richter model, we considered the distribution of the quantile of order (1 − 10 −4 ) of the GPD-imp model to randomize the upper bound of the Exponential distribution. From (8) and 12 Its asymptotic distribution is Normal, with mean 6.75 and variance 7.63 10 −2 calculated from (9), that we truncated to the lower bound equal to the maximum magnitude contained in the catalog m max,cat = 6.69 M w : Figure 13 shows the pdf of the distribution ofq N . Figure 2 shows the final distribution of magnitudes and Figure 3 shows the associated recurrence model compared to the Gutenberg-Richter straight line.…”

“…Probabilistic Seismic Hazard Analysis (PSHA) has become a fundamental tool in assessing seismic hazards and seismic input motions to evaluate critical facilities ( [2], [3]) and in developping codes at national or regional scale ( [15], [19]). Over the last 15 years, the PSHA practice has greatly improved, mainly motivated by research programs launched around the world ( [8], [29], [32], [33]).…”

Enhanced Seismic Response Prediction of Critical Structures via 3D Regional Scale Physics-Based Earthquake Simulation

“…State of the art recommendations, based on recent research works, state that the seismic motion has to be controlled at the "reference bedrock" in depth, or at least at the outcropping bedrock, in order to reduce the consequences of geological conformation and site-specific parameters uncertainties, instead of the free-field motion. In such a way, the site effects can be easier analyzed separately from the analysis of the seismic hazard (1 ). To this end, the development of physics-based 3D models for the simulation of earthquake ground motion has been largely increased with the exponential increase of the computational power.…”