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To be withdrawn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