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
- Garner Valley Geotechnical Array
- Eastern US site
- Western US site
- Detailed site characterization
- Measured ground motions
- Kappa and site term
- Surface wave testing 6
Savannah River Site - CEUS Sources with NGA-East GMM PEZ-N ECC-AM ECC-AM SRS SRS Charleston M6 virtual ruptures Gulf Coast Zone 7
Garner Valley Site - San Jacinto Fault with SWUS GMM San Jacinto Fault Zone Length: about 244 km Predominantly Right Lateral Slip Overall Slip Rate about 10-12 mm/yr SWUS GMM GV 17 spectral periods and up to 31 median models Reference VS30 = 760 m/sec Reference 0 = 40 msec 8
Equivalent Linear Analysis Savannah River Site Surface Spectra Response Approach Site AFs
- 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 Input Motions 9
Garner Valley Site Response Approach
=
Shear-Wave Velocity (m/s) Shear-Wave Velocity (m/s) ( )
GMM Profile Site Profile GMM Profile Site Profile 1.2 0
0 2000 4000 6000 0
0 2000 4000 6000 1 ( )
0.8 Sa (g) 0.6 50 0.4 2000 0.2 100 0 0.1 1 10 100 4000 Frequency (Hz) 150 6000 200 Depth (m) Depth (m) 250 8000 Site and GMM Profile 300 10000 0.6 350 0.5 0.4 12000 400 Sa (g) 0.3 0.2 0.1 450 14000 0 0.1 1 10 100 500 Frequency (Hz) 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
= 0 exp() 0 14
Kappa Correction of Surface Spectra
- High frequency decay is independent
- Kappa corrected amplification of strain level (Xu and Rathje 2019)
- Target kappa
= 0 + 1 x
- Kappa corrected FAS
_ =
15
Travel Time Randomization
- Travel time is lognormally distributed (Passeri et al. 2020)
- Implements Toro (1995) interlayer correlation model
- Travel time specific model Elevation (m) parameters
- Site class independent 16
Implementation of AFs into Hazard Calculation 5 Hz SRA Logic Tree 7 Miller &Rice (1983)
Terminal Branches Branches 17
Interpretation of Site Response Results 1
- The AFs computed for each 0.01s 0.9 0.05s 0.1s 0.2s branch of the logic tree can be 0.8 0.5s 0.7 0.8s 1.0s used to explore contributors to 0.6 5.0s Percent of total variance 10.0s 0.5 the epistemic uncertainty (Rodriguez-0.4 0.3 Marek et al. 2020) 0.2
- Variance contribution plots 0.1 0
- Tornado plots ppa oil pe of Ka Ro S tatio Ty pt n ile h of De ile Pr of
- Help identify which elements can Pr llow De Sh a ep be further characterized to Variance contribution plot for a non-identified site, shown only as an example reduce epistemic uncertainty 18
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