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PG&E DCPP SSHAC Study
LTSP SSHAC Level 3 Study Workshop 1 – SSHAC and Workshop Rules
William Lettis November 29, 2011
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• What is SSHAC?
- Objectives of the LTSP SSHAC Level 3 Study - Overview of SSHAC Process - SSHAC concept of (1) evaluation and (2) integration: capturing
views of informed technical community (ITC) and technically defensible interpretations (TDI)
- Workshop Structure and Ground Rules - Participant Roles and Responsibilities
SSHAC and Workshop Rules
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LTSP SSHAC Level 3 Objectives
(1) Develop fully hazard-informed SSC and GMC models for
update of the Diablo Canyon PSHA
(2) Provide increased regulatory assurance that the PSHA adequately captures uncertainties in data and scientific knowledge
(3) Identify important data needs for reducing uncertainties in significant SSC and GMC parameters that can be fulfilled by the ongoing LTSP field and research programs
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The SSHAC Process
A structured framework and procedure for conducting
multiple-expert assessments of input to PSHA
Procedures defined by the Senior Seismic Hazard
Analysis Committee (SSHAC)
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The SSHAC Process Several more recent updates on SSHAC Guidance (1) Hanks et al, 2009, Implementation of the SSHAC Guidelines for Level 3 and 4 PSHAs – Experience Gained from Actual Applications; USGS Open-File Report 2009-1093 (2) Coppersmith, Bommer, Kammerer and Ake, 2010, Implementation
Guidance for SSHAC Level 3 and 4 Processes; June 10, 2010 Probabilistic Safety Assessment and Management Conference
(3) Munson and Ake, 2010, Seismic Considerations for Western U.S. Sites June 16, 2010 ANS Conference (4) NRC, 2011, Practical Implementation Guidelines for SSHAC Level 3 and
4 Hazard Studies; Draft NUREG XXXX
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SSHAC Objective
Develop a methodology for obtaining reproducible, stable estimates of probabilistic seismic hazard at a site, including explicit quantification of uncertainty • Focused on Process for assessing uncertainty in the
PSHA model input assessments and for quantifying the uncertainty in PSHA results
• “Stability” is achieved by properly characterizing and quantifying uncertainty
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SSHAC Basic Principles for a PSHA
Principle 1: The goal of a SSHAC is “to represent the center, the body, and the range of technical interpretations that the larger technical community would have if they were to conduct the study”
Termed the “informed technical community” (ITC) by Budnitz et al (1997)
Termed the range of “technically defensible interpretations” (TDI) by NRC (2011, Draft)
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SSHAC Basic Principles for a PSHA (continued)
Principle 2: “It is absolutely necessary that there be a clear definition of ownership of the inputs into the PSHA, and hence ownership of the results of the PSHA”
• Ownership means intellectual responsibility • For SSHAC Level 3, Technical Integrator (TI) assumes
ownership – TI Team (Intellectual ownership) – As opposed to Owner/Sponsor (Project owner)
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Define specific roles of all participants Develop and disseminate complete database Consider range of TDI in evaluating alternative models and uncertainties Encourage interactive debate and learning in structured setting • Documented Workshops and Information
Build SSC and GMC modes to represent center, body, and range of technically defensible interpretations Provide hazard sensitivity feedback to understand implications of preliminary models and uncertainties Conduct participatory (continual) peer review
Key Features of a SSHAC Process
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Diablo Canyon – SSHAC Level 3 Seismic Source and Ground Motion Characterization Project
Ground Rules for Workshops - The workshops are an opportunity for the TI team to: • Exchange data • Present interpretations • Challenge and defend technical hypotheses • Gain information on the project • Interact and ask questions Therefore, the focus of each workshop is for the TI Team Conduct of the technical discussions at the workshops will be at the highest professional level -Discussions will be among the TI team, Presenters and Experts - No Niggling (petty criticism, unimportant issues) - PPRP observers at Workshops 1 & 2, active participants in Workshops 3 & 4 - Meeting with PPRP at end of workshop for informal comments; to be followed by written comments - TI team runs the workshops and is responsible for keeping schedule, logistics, etc.
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Probabilistic Seismic Hazard Analysis (PSHA)
Reiter (1990)
Source Geometry
Earthquake Recurrence
Seismic Source Characterization:
SSC Model
Ground Motion Characterization:
GMC Model
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SSHAC Participants and Roles
SSHAC defines several key concepts and roles (Budnitz et al, 1997; NRC, 2011, Draft)
• Project Technical Integrator • Technical Integrator (TI) • Expert roles:
– Evaluator expert – Resource expert – Proponent expert – Hazard analyst – Database manager
• Participatory Peer Review Panel 8
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Expert Roles
Project Technical Integrator An individual that serves as coordinator/facilitator of combined
SSC and GMC SSHAC Study; Interface with Project Manager and Project Sponsor
Technical Integrator An individual or small team of evaluator experts that serves as
integrator for the technical assessments Structures and documents information exchanges Stages effective debates and interactions in critical areas Responsible for capturing range of TDI and considering them in
the evaluation process Responsible for documentation Intellectual ownership of final model
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TI Team Responsibilities
Evaluation • Identification of important issues and applicable data • Interaction with proponent and resource experts • Evaluate existing data, alternative models and methods from the
larger technical community, and need for additional information
Integration • Develop range of alternative models and uncertainties, given
available data and proponent viewpoints, that represent the center, body, and range of technically defensible interpretations
• Imagine community’s views if they had gone through the same evaluation process
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Expert Roles (continued)
Resource Expert Personal knowledge of a particular data set, interpretation and/or hypothesis Active or past participant in research of a particular topic (issue or data set) Participates in professional community through meetings and literature Presents data and information without proponent bias
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Expert Roles (continued)
Proponent Expert An expert who advocates a particular hypothesis, interpretation or model Common role in science Peer review in professional meetings and literature Opinions may range from mainstream to extreme (or outlier) views
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Participatory Peer Review Panel
Participatory Peer Review Panel (PPRP) Panel of individuals with SSHAC and/or PSHA experience
that provide peer review of the SSHAC implementation process
PPRP need not necessarily have prior technical knowledge of the site but provides technical review of the PSHA input parameters and uncertainties
PPRP assures that the range of TDI is considered and evaluated through implementation of the SSHAC process
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PPRP Responsibilities
Continual review of technical and process aspects of the project Technical • Quality of the databases developed or compiled? • Have all data, models, and methods within the techncial community
been considered? • Is the evaluation of the available data reasonable? • Has uncertainty been properly evaluated and captured in the
integration process? • Are models and assessments defensible and justified? Process • Are activities consistent with SSHAC-3 process? • Have available data, models, and methods been considered? • Is documentation complete and clear? Endorsement
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Process and Technical R
eview
PPRP
Evaluation of M
odels to Form C
omposite D
istribution
TI Team Hazard
sensitivity calculations
Preliminary database
WORKSHOP 1: Significant Issues, Available Data and
Data Needs Resource Experts
Additional data collection & analysis
WORKSHOP 2: Alternative Models
Resource Experts (?)
Proponent Experts
Final database Preliminary SSC and GMC models
WORKSHOP 3: Presentation of Models and Hazard Sensitivity Feedback
Database C
ompilation
Technical Staff & Contractors
Evaluation Integration Workshop 4: Final Briefing SSC and GMC models, then final hazard
calculations, Documentation of all technical bases
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LTSP SSHAC Level 3 Study
Activities Performed to Date Completion of Draft and Final Project Plan - Scope and Schedule - Including PPRP Review and Comment Identification of Project Participants/Contracts Completion of Initial Data Compilation and Sensitivity Analysis Completion of Workshop 0 – “Kickoff meeting, Project Plan and Significant Issues” Preparation for Workshop 1 – “Significant Issues, Available Data and Data Needs” - Document SSC V0 Model and GMC V0 Model - Identify Resource Experts and Discussion Topics - PPRP Review - Convene several SSC and GMC Working Meetings
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Diablo canyon SSHAC Level 3 Project Plan
Project Plan includes (1) Formal Structured Workshops with Resource and
Proponent Experts (2) Working Meetings of the SSC and GMC TI Teams (3) Interface opportunities between the GMC and SSC TI
Teams and ongoing DCPP field and research programs (4) Comprehensive documented SSC and GMC database (5) Explicit process of Evaluation and Integration (6) Continual participatory peer review
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Workshop 0 – Kick-off Meeting, Project Plan, Significant Issues
Workshop 1 – Significant Issues, Available Data, Data Needs - Resource Experts Workshop 2 – Alternative Models and Proponent Interpretations
- Proponent Experts
Workshop 3a, b, c – Preliminary Model and Hazard Sensitivity
Workshop 4 – Final Model Briefing
LTSP SSHAC Level 3 Workshops
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LTSP SSHAC Level 3 Study
Workshop 1 – Significant Issues, Available Data and Data Needs • Goals Identify significant technical issues important to hazard Provide an opportunity for the TI team to understand available data
relevant significant technical issues Identify additional data needs or data gaps to address significant
issues or uncertainties
- Presentations of data and interpretations directly from the Resource Experts, including discussion topics requested by the TI team
- Question/answer period
Attendees: TI Staff, Evaluator Team, PPRP, Resource Experts and Hazard Analyst.
Length: 3 days.
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PG&E DCPP SSHAC Study
Diablo Canyon SSHAC Level 3 Study
Workshop 1 – SSHAC Training
Questions and Comments?
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LTSP SSHAC Level 3 Study Workshop 0 – Kick-off Meeting, Project Plan and Significant Issues
Goals of the workshop - Introduce participants - Introduce projects goals, expectations, schedule - Review Project Plan - Identify key hazard-significant SSC and GMC issues - Review available data, including availability, formats, quality, and uncertainties - Identify Resource Experts for Workshop 1 and Tentative Proponent Experts for Workshop 2 - Identify the project path forward - PPRP feedback and comments
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Regulatory Basis for SSHAC SSHAC Provides an Accepted Assessment Process
The principal geologic and seismic considerations for site suitability and engineering criteria are given in 10 CFR 100.23 and Appendix S to Part 50. -- 10 CFR 100.23 identifies a PSHA as an acceptable means to address the - uncertainties in determination of the SSE.
Regulatory Guide 1.208 provides more detailed guidance on: - Investigations and applications of PSHA and development of the ground motion
response spectra (GMRS). - Application of the Senior Seismic Hazard Analysis Committee (SSHAC)
guidelines for determination of source characterization and GMPEs (NUREG/CR-6372)
- Integrated site response (NUREG/CR-6728) - RG 1.208 states: “The guidelines detailed in NUREG/CR-6372 should be
incorporated into the PSHA process to the extent possible.”
ANS/ANSI Standards 2.27 (Criteria for Investigations of Nuclear Facility Sites for Seismic Hazard Assessments) and 2.29 (Probabilistic Seismic Hazards Analysis) have been issued subsequent to the publication of RG 1.208 Detailed implementation guidance for Study Level 3 and 4 projects (NRC 2011, NUREG, in draft)
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PG&E DCPP SSHAC Study
William Lettis November 29, 2011
Diablo Canyon SSHAC Level 3 Study
Workshop 1 – Project plan and
Schedule
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Diablo Canyon SSHAC Level 3 Scope Review of Draft Project Plan and Schedule
Outline of project plan • Objectives • Description of SSHAC Methodology • Selection of SSHAC Level • Project Organization • Work Plan • Schedule • Quality Assurance
Conforms to Kammerer and Ake (2011) Draft NUREG Subject to PPRP Review and Revision
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Diablo Canyon SSHAC Level 3 Objectives
(1) Develop fully hazard-informed SSC and GMC models for use in
the Blue Castle PSHA for development of site GMRS (2) Provide regulatory assurance that the site PSHA adequately
captures uncertainties in data and scientific knowledge (3) Identify important data needs for reducing uncertainties in
significant SSC and GMC parameters that can be fulfilled by the ongoing Diablo Canyon field and research program
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Selection of SSHAC Level 3 (1) SSHAC Methodology defines four different levels of study distinguished
by increasing level of sophistication, resources, and participation by technical experts
(2) NRC expectations are that a SSHAC Level 3 or 4 study will be performed for sites in the WUS in areas where a similar level study has not previously been performed and accepted by the NRC
(3) A SSHAC Level 3 or 4 study should be performed in regions of - active, complex tectonic settings
- Potential for significant public impact/scrutiny - Significant Regulatory scrutiny
(4) Based on this guidance a SSHAC Level 3 study has been selected for the DCPP LTSP Update
(5) A SSHAC Level 4 study is not being used because of (1) significantly increased schedule requirement, (2) Iterative process of Evaluation and Integration, and (3) relatively minor increase in regulatory assurance associated with a Level 4 study
(6) - “From the regulatory perspective of the NRC, there is no essential difference between Level 3 and 4 studies” (NRC, 2011, Draft NUREG)
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SSHAC Level 3 Workshops (cont’d)
Workshops 2a, b and c – Preliminary Model and Hazard Feedback Workshops - Present preliminary logic tree of alternative models including discussion of epistemic uncertainty - Iterative process of data acquisition, evaluation and integration for each workshop - Present sensitivity analyses by Hazard Analyst - Identify additional sensitivity analyses to be performed by Hazard Analyst (if any) Attendees: Same as Workshop 1 (selected Resource and Proponent Experts only) Length: 1 to 2 days - Working meetings to develop V2, V3 and Final models and for Hazard Analyst to perform sensitivity analyses
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SSHAC Level 3 Workshops (cont’d)
Workshop 3 – Final Model and Hazard Feedback Workshop - Present Final SSC V4 and GMC V2 Models - Present final hazard sensitivity results - Finalize fault data sheets and SSC and GMC documentation Attendees: TI Staff, Evaluator team, PPRP, Hazard Analyst and selected resource and/or proponent expert observers Length: 1 to 2 days - Working meetings to develop Final Model (incorporating final PPRP comments)
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SSHAC Level 3 Workshops (cont’d) Final Briefing Meeting – Presentation of Final Model - Present Final logic tree of alternative models for SSC and GMC for use in the LTSP PSHA Update Attendees: TI Staff, Evaluator team, PPRP Length: 1 day
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