Dr. Annie Kammerer
IAEA International Workshop on Seismic Safety of Nuclear Installations
March 2010
With key slides on ASCE43-05 by:
Dr. Robert Budnitz, LBNL
Dr. Dave McCallan, LLNL
US Regulatory Guide 1.208
Performance-Based Approach to Define the
Site-Specific Earthquake Ground Motion
Safety Standards Series hierarchy
Safety Guides
Requirements
Safety Fundamentals
US Code of
Federal
Regulations
Regulatory
Guides
IAEA
US & IAEA documentation
International Atomic Energy Agency3/17/2010 12
Safety GuidesGuides
NRC
NUREGsSafety Reports &
TECDOCs
10 CFR Part 50 Appendix S defines SSE as
“Safe-shutdown earthquake ground motion is
the vibratory ground motion for which
certain structures, systems, and components
must be designed to remain functional”
10 CFR Part 50 also states that “The nuclear
power plant must be designed so that, if the
US Code of Federal Regulations
Safe Shutdown Earthquake Ground Motion
occurs, certain structures, systems, and
components will remain functional and within
applicable stress, strain, and deformation
limits.”
10 CFR Part 50 Appendix A states “Structures, systems, and components important to safety shall be designed to withstand the effects of natural
10 CFR Part 100.23 “Geologic and Seismic SitingCriteria” requires that the applicant determine the SSE and its uncertainty, the potential for surface tectonic and nontectonic deformations.
US Code of Federal Regulations
be designed to withstand the effects of natural phenomena such as earthquakes, …., without loss of capability to perform their safety functions”.
IAEA
US documentation and regulations
Seismic
Hazard
NS-G-3.3
NRC
Regulatory
Guide 1.208
STANDARD REVIEW PLAN(NUREG 0-800)
US documentation and regulations
Standard Review Plan
NRC NUREG 0-800 NRC DC/COL-ISG-017
(site response & SSI)
Interim Staff Guidance
• A Performance-Based Approach to Definethe Site-Specific Earthquake Ground Motion
• Hazard x Performance Risk
• NRC is “Risk Informed” as per 1997 commission directive and uses probabilistic inputs and performance-based design
• Ground motion and SSC performance target risk goals (core damage ~10-6/year)
• Overall plant risk assessed through Seismic Probabilistic Risk Assessment (SPRA)
Risk-Informed Regulation
To be withdrawn
Hazard + Adequate
Performance
Acceptable
Risk
Key Documents for Understanding
Technical Basis of Approach
Performance Based Design
Risk Reduction Ratio reduces
performance goals below hazard
Hazard Modified to Obtain SSE
DF=0.6 (AR)0.8
AR=UHRS at 10-5
UHRS at 10-4
Slope of the
hazard
curve
with a minimum of 1
Outcome of the NRC 1x10-5 Frequency of Onset
of Significant Inelastic Deformation (FOSID)
• Now the key is to appropriately define the Hazard…which is the goal of RG1.208
• The Ground Motion Response Spectrum (GMRS) is the site-specific uniform hazard response spectrum with an annual probability of 10-4 spectrum for an elevation in the soil or rock column that is meaningful for the facility
Use of RG1.208 to Determine Hazard
rock column that is meaningful for the facility
• GMRS should be developed for horizontal and vertical components
• Determination of GMRS requires many inputs:
– Seismic source characterization
– Ground motion prediction equations (GMPE)
– Dynamic site properties for site response
• And appropriate approaches to develop and combine them:
- SSHAC guidelines for determination of source
characterization and GMPEs (NUREG/CR-6372)
- PSHA techniques
- Integrated site response (NUREG/CR-6728)
Use of RG1.208 to Determine Hazard
Source
Characterization
Ground motion
prediction equations
Central and Eastern US Seismic
Source Characterization project for
Nuclear Facilities (CEUS SSC)
Next Generation Attenuation
Relationships for the Central and
Eastern (NGA-East)
Framework for large
PSHA studies
Eastern (NGA-East)
Recommendations for Application
of the SSHAC Guidelines
NRC application of RG1.208
• Appropriate data collection and field investigation efforts to meet 10 CFR 100.23 requirements
Site (>1km)
Site Area (>8 km)
Site Vicinity (>40 km)
Increasing level of
effort close to site.
However, any seismic
sources that may
impact hazard should
be appropriately
Data Collection in RG1.208
Site Vicinity (>40 km)
Site Region (>320 km)
be appropriately
assessed.
Regional source
models (e.g. new CEUS SSC model)
must still be refined
with site-specific
information
SSHAC Guidelines
• NUREG/CR-6372, “Recommendations for
Probabilistic Seismic Hazard Analysis: Guidance
on Uncertainty and Use of Experts”
• SSHAC provides a framework for incorporating
experts into scientific assessments through
18
experts into scientific assessments through
structured processes and interactions
• Fundamental concepts behind guidelines• Views of the larger technical community are fundamental inputs
• Competing scientific hypotheses can be considered and uncertainties captured
• PSHA is a snapshot in time of our knowledge and uncertainties
Goals of SSHAC
• “To represent the center, the body, and the range of the technical interpretations that the larger informed technical community would have if they were to conduct the study”
19
conduct the study”
– Increases assurance that uncertainties have
been captured
– Leads to regulatory stability
– Can be peer reviewed by those with
comparable knowledge of the community
SSHAC Guidelines
• NRC Undertaking Program to develop NUREG
on “Implementation of SSHAC Guidelines for
Level 3 and 4 Processes”
– NRC Sponsored USGS
Workshops resulting in USGS
20
Workshops resulting in USGS
OFR 2009-1093
– Draft NUREG (exp. 2010)
– Public Workshop on Level 3
studies to capture additional
lessons learned
– Finalize NUREG
• Geotechnical hazards beyond ground shaking (e.g. liquefaction, direct fault rupture)
• Choice of epsilon cutoff in PSHA
• Site response approaches and application of de-aggregation for simplified methods (e.g. NUREG/CR-6728 method 2a)
• Earthquake record development for time-history based analyses
Additional topics in RG1.208
Certified Seismic Design
Response Spectrum (CSDRS)
Horizontal Design Response Spectra
Design: AP1000
2% Damping
3% Damping
4% Damping
5% Damping
7% Damping
Slides provided by NRC Office of New Reactors
Certified Seismic Design
Response Spectrum (CSDRS)
Horizontal SSE Design Spectra
Design: ABWR
Slides provided by NRC Office of New Reactors
Site SSE (GRMS) compared to CSDRS
GRMS is based on
site characterization
and it is determined
from detailed
seismic hazard Certified
Design seismic hazard
studies
CSDRS is based
on engineering
design of a plant.
CSDRS is chosen
by the vendor and
used as review
spectrum Slides provided by NRC
Office of New Reactors
CSDRS
Site Spectrum
GRMS
Thank You
Title Goes Here
US Regulatory Guide 1.208
Performance-Based Approach to Define the
Site-Specific Earthquake Ground Motion
HCLPF