ML21272A014
| ML21272A014 | |
| Person / Time | |
|---|---|
| Issue date: | 01/28/2020 |
| From: | Jon Ake, Miriam Juckett Office of Nuclear Regulatory Research, Southwest Research Institute |
| To: | |
| S. Stovall | |
| Shared Package | |
| ML21272A001 | List: |
| References | |
| Download: ML21272A014 (14) | |
Text
U.S. Nuclear Regulator y Commission SSHAC Level 2 Workshop:
Site Response
Introduction and Objectives Presentation Miriam Juckett,SwRI Jon Ake, NRC Januar y 28, 2020
1 Outline
Workshop Logistics Over view of SSHAC Motivation and Objective for this Project Direction and Scope Workshop Logistics
On-site logistics
- Emergency exits
- Restrooms
- WiFi
- Parking
- Snacks/Drinks/Coffee
- Lunches - order form
- Dinners - update and locations Workshop Materials Sign-in Sheet and Introductions What is SSHAC?
Senior Seismic Hazard Analysis Committee (SSHAC) - a group established in the 1990s with the goal of investigating the reason(s) for differences in two major probabilistic seismic hazard analysis studies for the central and eastern U.S. conducted in the 1980s.
The SSHAC concluded the primar y reason for the differences were procedural rather than technical.
In their repor t (NUREG-6372) the group made a number of suggestions for conducting future studies that would (hopefully) minimize the impact of procedural issues.
The guidance has been applied in a number of studies throughout the world.
Guidance subsequently expanded and updated in NUREG-2117 and 2213.
Goal of a SSHAC Process
The fundamental goal of a SSHAC process is to properly carr y out and completely document the activities of evaluation and integration, defined as:
Evaluation:The consideration of the complete set of data, models, and methods proposed by the larger technical community that are relevant to the hazard analysis.
Integration: Representing the center, body, and range of technically defensible interpretations [CBR of the TDI] in light of the evaluation process (i.e., informed by the assessment of existing data, models, and methods). N U REG-2117/2213
5 Key SSHAC Concepts
These five features are essential for all SSHAC hazard studies regardless of the SSHAC Level and distinguish SSHAC studies from non-SSHAC studies Clearly defined roles for all par ticipants,associated with each role. including the responsibilities and attributes
Objective evaluation of all available data,the characterization of the hazard at the site. models, and methods that could be relevant to
Integration of the outcome of the evaluation process into models that reflect both the best estimate of each element of the hazard input with the current state of knowledge and the associated uncer tainty. This distribution is referred to as the Center, Body, and Range of Technically-Defensible Interpretations, or the CBR of the TDI.
Documentation of the study with sufficient detail to allow reproduction of the hazard analyses.
Independent par ticipator y peer review is required to confirm that the evaluation did consider relevant data, models, and methods, and that the evaluation was conducted objectively and without bias. The peer review is conducted following a par ticipator y or continual process throughout the entire project.
Key SSHAC Concepts
Capturing the Center, Body and Range of Technically Defensible interpretations
(the CBR of TDI)
SSHAC Level 2 Workflow
Note: replace SSC and GMC with SRA Participant Role (Organization) Responsibilities SSHAC Team Roles Project Manager Miriam Juckett (CNWRA)Provides overall coordination and responsibility for organizational and administrative aspects of the project. Is the liaison between the Sponsor and the project participants, as needed.
Technical Integration Team Dr. Adrian Rodriguez-Marek (TI Responsible for developing the models and Lead and Members Lead; Independent Consultant) final recommendations for incorporation of Dr. Jon Ake (NRC) site response.
Dr. Cliff Munson (NRC)
Dr. Ellen Rathje (Independent Consultant)
Hazard Analysts and Dr. Scott Stovall (NRC) Responsible for establishing and managing Database Managers Dr. Thomas Weaver (NRC) necessary data sets and executing calculations and sensitivity studies and documenting the final results according to the inputs developed by the TI Team.
Sponsor Represented by NRC Contracting Funds the study and provides input as Officers Representative, Dr. Scott requested on the Project Plan; works with Stovall (NRC) Project Manager to ensure that the purpose, process, and outcomes of the study will meet Sponsor goals.
Participatory Peer Review Dr. Dogan Seber (NRC) Responsible for technical and process Panel (PPRP) Dr. John Stamatakos (CNWRA) reviews to ensure the SSHAC approach is Dr. Jeff Kimball (Independent implemented per regulatory guidance At Consultant) the end of the study, if acceptable, documents approval in a closure letter.
Seismic Design/Analysis For Nuclear Plants
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2 Motivation
All recent PSHA studies for commercial nuclear facilities in the U.S.motion characterization (GMC) and seismic source characterization (SSC) studies carried have included ground out following the SSHAC framework and guidance (generally Level 3).
However, site response analyses (SRA) have typically been conducted as a discrete activity outside of the SSHAC framework.
Is it practical and effective to conduct the SRA following the SSHAC guidance as well and receive the enhanced regulator y assurance that comes with that process?
Given the enhanced focus on risk informed decision making,for incorporating uncer tainties into the site-specific hazard calculations? what are the best method(s)
Current practice for PSHAs conducted for critical facilities often incorporates the concept of par tially non-ergodic PSHA, incorporating a single-station sigma as the aleator y variability in the reference rock PSHA.
- Single-station sigma removes the site -to -site variability por tion of the fully ergodic sigma necessitating the proper characterization of epistemic or knowledge-based uncer tainties in the site term (e.g., in site response) in the final hazard calculations.
Objective and Caveat
Objective: To evaluate how site response analysis results are integrated into the PSHA to properly account for the epistemic uncer tainty and aleator y variability of relevant site response data, models, and methods.
- Focus on identifying epistemic uncer tainty vs. aleator y variability, then quantify each in the site term (for each example site)
- Perform a Senior Seismic Hazard Analysis Committee (SSHAC) Level 2 study to investigate how site response inputs should be defined and quantified, and subsequently incorporated into PSHA computations.
Caveatpurpose of this study is not to re -:This project may utilize data from existing sites.evaluate the seismic hazard at a specific site, However, the or outcomes of any prior assessments. The outcomes will be used to inform future site response analyses and provide information to the Sponsor (NRC) for potential changes or enhancements to regulator y guidance.
Site Selection Criteria
Criterion WUS: Garner CEUS:
Valley Array Savannah River Site Suitable Site Properties for Nuclear Facility Potential for Nonlinear Behavior Abundant Site Characterization*
Local Ground Motion Recordings X Realistic Reference Hazard Level X
- Site characterization data must be publicly available or available in a time frame consistent with project schedule Future Direction and Scope
Project Direction: This is a research project.
- Attempt to satisfy objective, answer motivating questions. H ow ev e r-direction will evolve (answers lead to new questions, comments/insights from PPRP and workshop).
- As direction evolves, tr y to capture in Project Plan updates Scope:This is a research project. Project resources will ultimately constrain the scope.
In addition to workshop,TI Team will be conducting interactions (phone inter views) with other exper ts not present at the WS.