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.

Highlights

  • The second BESTPSHANI workshop was a great opportunity to present the progress made through the SINAPS@ project to the international community involved in seismic risk research and its management, in the framework of nuclear safety

  • The long experience of French nuclear facilities safety reviews that faced the lack of any approved dedicated documentation that described acceptable practices for existing facilities;

  • The scientific challenges raised by recent mega earthquakes in Japan that struck nuclear power plants, and the unavoidable questions of the engineering practices, especially to assess the seismic margins of nuclear facilities

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Summary

Introduction

In France in particular, there was no consensual rationale (and at the time, no regulatory documents), this lack of approved practice for assessing of the ultimate seismic capacity of structures, systems and components has resulted in notably increased difficulties since the introduction of the ‘beyond design’ seismic levels, such as associated with the hard core in France These difficulties happened in France during the post-Fukushima complementary safety studies, and even though every seismic expert agreed on the existence of these margins, there was no confidence in their values.

Seismic Risk Regulatory Framework in France for Nuclear Facilities
Preamble
Quality Assurance
Basic Data in Metropolitan France
Seismic Source Characteristics
Seismic Source Characterization in Metropolitan France
Seismic Motion Prediction
Toward Physical Based Strong Motion Prediction
Bayesian Tool as an Objective Alternative to Expert Judgment
Site-Specific SHA
The Scientific Context
Objectives of WP2
New seismic data acquisition to validate:
Soil-Structure Coupling
Validation of Nonlinear Soil Models for Strong Ground Motion
Validation Site and Data Acquisition at the Argostoli Test Site
Numerical Developments Performed in WP2
Synthesis and Recommendations
Scientific Challenges of WP3
Structure Modeling
Structural Applications
WP4 Seismic Risk Assessment
Scientific Challenges of WP4
Main Scientific Advances from WP4 Actions
Proposals for Recommendations from WP4 Achievements
Scientific Challenges of WP5
Scientific Context
Objectives
Work Performed
Main Achievements
Outlook
WP 6 Dissemination of Knowledge
Conclusions and Perspectives
Findings
Synthesis
Full Text
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