ML21053A043
| ML21053A043 | |
| Person / Time | |
|---|---|
| Issue date: | 10/22/2020 |
| From: | Jon Ake, Miriam Juckett, Clifford Munson, Rathje E, Rodriguez-Marek A, Scott Stovall, Thomas Weaver Office of Nuclear Reactor Regulation, Office of Nuclear Regulatory Research, Southwest Research Institute, Univ of Texas, Virginia Tech |
| To: | Office of Nuclear Reactor Regulation, Office of Nuclear Regulatory Research |
| T. Weaver | |
| References | |
| Download: ML21053A043 (19) | |
Text
SSHAC Level 2 Site Response Project Adrian Rodriguez-Marek, PhD, Virginia Tech Ellen Rathje, PhD, PE, University of Texas Jon Ake, PhD, US NRC Cliff Munson, PhD, US NRC Scott Stovall, PhD, US NRC Thomas Weaver, PhD, PE, US NRC Miriam Juckett, Southwest Research Institute
Overview
- Project Purpose and Plan
- Study Sites
- Site Response Analysis Approach
- Site Response Logic Trees
- Implementation of Site Response Results 2
Project Purpose
- Perform pilot study implementing site response within a SSHAC process at two example sites
- Demonstrate characterization of site term (site response) epistemic uncertainty
- Address methods to differentiate between epistemic uncertainty and aleatory variability for site response
- Evaluate alternative approaches for incorporating site response results into the PSHA
- Downstream applications
- PRA 3
Project Plan
- Public Workshop, January 2020
- Input from technical experts
- Interviews with technical experts, March 2020
- Technical Integration Team Meetings, January 2020 - Present
- Sensitivity studies
- Developing logic tree
- Hazard evaluation
- Draft Project Report, December 2021
- PPRP Comments - January 2021
- Final Report - March 2021 5
Study Sites
- Savannah River Site
- Eastern US site
- Detailed site characterization
- Garner Valley Geotechnical Array
- Western US site
- Measured ground motions
- Kappa and site term
- Surface wave testing 6
Savannah River Site - CEUS Sources with NGA-East GMM Gulf Coast Zone ECC-AM ECC-AM PEZ-N SRS SRS Charleston M6 virtual ruptures 7
Garner Valley Site - San Jacinto Fault with SWUS GMM GV San Jacinto Fault Zone Length: about 244 km Predominantly Right Lateral Slip Overall Slip Rate about 10-12 mm/yr SWUS GMM 17 spectral periods and up to 31 median models Reference VS30 = 760 m/sec Reference 0 = 40 msec 8
Savannah River Site Response Approach
- Point source model used to develop input at reference rock (Vs = 3000 m/s)
- Equivalent linear, RVT
- One branch will kappa correct surface motion
- Non-linear analyses to inform amplification epistemic uncertainty Equivalent Linear Analysis 9
Input Motions Site AFs Surface Spectra
Garner Valley Site Response Approach 0
0.1 0.2 0.3 0.4 0.5 0.6 0.1 1
10 100 Sa (g)
Frequency (Hz) 0 0.2 0.4 0.6 0.8 1
1.2 0.1 1
10 100 Sa (g)
Frequency (Hz)
()
=
()
0 2000 4000 6000 8000 10000 12000 14000 0
2000 4000 6000 Depth (m)
Shear-Wave Velocity (m/s)
GMM Profile Site Profile Site and GMM Profile 0
50 100 150 200 250 300 350 400 450 500 0
2000 4000 6000 Depth (m)
Shear-Wave Velocity (m/s)
GMM Profile Site Profile 10
Savannah River Logic Tree 11
Garner Valley Logic Tree 12
MRD Curves Randomization Strength Correction 13
Site Kappa
- Savannah River use empirical relationships
- Garner Valley use site recordings 14
= 0exp()
0
Kappa Correction of Surface Spectra
- High frequency decay is independent of strain level (Xu and Rathje 2019)
- Target kappa
= 0 + 1 x
- Kappa corrected FAS
_=
15
- Kappa corrected amplification
Travel Time Randomization
- Travel time is lognormally distributed (Passeri et al. 2020)
- Implements Toro (1995) interlayer correlation model
- Travel time specific model parameters
- Site class independent 16 Elevation (m)
Implementation of AFs into Hazard Calculation 17 SRA Logic Tree Terminal Branches 7 Miller &Rice (1983)
Branches 5 Hz
Interpretation of Site Response Results
- The AFs computed for each branch of the logic tree can be used to explore contributors to the epistemic uncertainty (Rodriguez-Marek et al. 2020)
- Variance contribution plots
- Tornado plots
- Help identify which elements can be further characterized to reduce epistemic uncertainty 18 Deep Profile Rotation Shallow Profile Type Depth of Soil Kappa 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Percent of total variance 0.01s 0.05s 0.1s 0.2s 0.5s 0.8s 1.0s 5.0s 10.0s Variance contribution plot for a non-identified site, shown only as an example
Summary
- SSHAC site response pilot study is in progress
- Characterizes site term epistemic uncertainty using logic trees
- Approach 3 and 4 will be implemented
- Study to explore handoffs to downstream uses of site response analysis
- Lessons learned from this study will inform updates to RG 1.208 19