An Overview of Seismic Research and Regulations at the US NRC

Transcription

1 Preparing for the Nuclear Renaissance: An Overview of Seismic Research and Regulations at the US NRC UC Davis Dr. Annie Kammerer, P.E. January

2 History Atomic Energy Commission (1954) Energy Reorganization Act of 1974 Department of Energy Nuclear weapons, promotion of nuclear power, care of lowlevel radioactive waste, and other energy-related work Nuclear Regulatory Commission Regulation of the civilian uses of nuclear materials including power production, medical and other uses Nuclear Non-Proliferation Act of 1978 Limits the spread of nuclear weapons. Established criteria governing U.S. nuclear exports licensed by the NRC and strengthened international safeguards system 2

3 History 1950s to 1970s US built plants 1979 Three Mile Island Accident 1986 Chernobyl Nuclear Disaster 435 nuclear plants in 30 countries generating 16% of total power (104 in US) New financial incentives in US energy policy 3

4 Organization Presidential Appointees Congressional Oversight Existing and New Reactor Licensing Yucca Mountain Nuclear Facility Research 4

5 Regulations Code of Federal Regulations Regulatory Guidance Guidance on how regulations are interpreted by NRC staff Not required but closely followed by industry (de facto regulations) Standard Review Plan Checklist that regulators use during reviews NUREG and NUREG/CR Reports that provide technical basis 5

6 New Regulatory Guide A Performance-Based Approach to Define the Site-Specific Earthquake Ground Motion Safe Shutdown Earthquake Ground Motion (SSE) 10,000 year probabilistic motion with design factors Targets frequency of onset of inelastic behavior Operating-Basis Earthquake Ground Motion (OBE) Half of SSE loading plant must be closed and inspected Soil-Structure-Interaction Guidance under development 6

7 Certified Plant Design Standardization of plant designs Use of certified design spectrum Site-specific spectrum compared with certified design spectrum Floor spectra from SSI used for design of contents 7

8 For each spectral frequency + + = 8

9 For each spectral frequency + + = Chapter 2 Earth Science & Natural Hazards Chapter 3 Earthquake Engineering Chapter 4 International Activities Chapter 5 Regulatory Guides 9

10 = For each spectral frequency Integrated Planning for Multidisciplinary work 10

11 Active (07) Upcoming (08) Monitoring (09+) Awaiting NGA (09+) Long term (09+) = For each spectral frequency Long-Term Planning of current and future projects 11

12 Workshops and Next Generation approaches NRC initiated early seismic hazard work Seismic research moving from the development of individual tools and methods Different databases, gray literature, proprietary reports, proprietary software The now mature field is moving to integration through workshops, working groups and next generation approaches Common databases & inputs, community consensus, documentation of thought processes, outliers & uncertainties better understood 12

13 Workshops and Next Generation approaches Consistent, complete, and agreed upon data sets and information All key experts in the research area involved Next Generation implies fundamental redevelopment of technical tools or approaches Both best estimates & estimates of uncertainties 13

14 Incoherency Research Key Ideas Wave Passage Effects Scattering Effects coherency = cross correlation of the phase angles of the Fourier spectra of two motions Fourier amplitude doesn t matter 14

15 Scattering Function of distance and frequency Function of material hardness? Only one hard rock site (w/ multiple events) 15

16 Pinyon Flat Seismograph Array in Plan View arrows show seismograph locations 16

17 Example of Set of Array Data Anomalous records were removed (See the funny red one?) 17

18 Updated ITF Model from 12/06 Common Understanding Phase angles of Fourier spectra stay coherent Coherency Phase angles of Fourier spectra are random Frequency (Hz) 18

19 Structure Stick Model with Outriggers and Offset Mass Centers Based on Westinghouse AP1000 Plants Outriggers and offset masses explore rocking and torsion Sticks linked above foundation SCV 417l 65' l 417out -20' 120mc 406 l -20' l mcl Z ASB SCV Y CIS l 401 l l 150' ' l -10' 310l -10' l 80 l 1 X ASB 75' 120 l 75' l 310out l 120out -10' 538mcl -10' 535mcl -10' 538 l -10' l 535 Node Number Location 401 Base of Steel Containment Vessel 406 Low on Steel Containment Vessel 417 Top of Steel Containment Vessel 417out Steel Containment Vessel Outrigger 1 Foundation of Auxiliary Shield Building 80 Low on Auxiliary Shield Building 80mc Low on Auxiliary Shield Building Mass Center 120 Top of Auxiliary Building 120out Top of Auxiliary Building Outrigger 120mc Top of Auxiliary Building Mass Center 310 Top of Shield Building 310out Shield Building Outrigger 5 Base of Containment Internal Structure 535 Low on Containment Internal Structure 535mc Low on Containment Internal Structure Mass Center 538 Top of Containment Internal Structure 538out Top of Containment Internal Structure Outrigger 538mc Top of Containment Internal Structure Mass Center l 5 CIS 538out l 75' 19

20 Implementation in SSI Cross correlation of every foundation node point using incoherency matrix based on ITF (includes non-diagonal elements) 20

21 Free-Field vs. SSI and Incoherency ITF & SSI 1.8 Response Spectra, Foundation, x-direction 1.6 SSI, Incoherent FIM, x-direction 1.4 Fixed Base, x-direction Spectral Acceleration (g) Horizontal Motion Frequency (Hz) 21

22 Impact of Incoherency in SSI SSI, Coherent, x-direction SSI, Incoherent, x-direction Response Spectra, Foundation, x-direction SSI, Incoherent FIM, x-direction 1.4 Fixed Base, x-direction Spectral Acceleration (g) Horizontal Motion Frequency (Hz) 22

23 Vertical Translation & Rocking Transfer Functions Rock Site, 150x150 fdn, Vertical & Rocking 1.0 Incoherency Transfer Function KEY POINT: Incoherency increases rocking and rotation in SSI Is not accounting for incoherency really conservative? Frequency CLASSI Vertical Translation SASSI Vertical Translation CLASSI Translation due to Rocking SASSI Translation due to Rocking 23

24 Active (07) Upcoming (08) Monitoring (09+) Awaiting NGA (09+) Long term (09+) = For each spectral frequency 2.2 Mmax ( 07) Key Seismic Zone Updates ( 08) Sensitivity & uncertainty study to address issues and prioritize research needs ( 08) 2.3 Next Generation Attenuation (NGA-East) ( 07) 2.4 Application of SSHAC Guidelines ( 07) 24

25 Before NGA-West After NGA-East Peak Acceleration (g) Attenuation Relations, SS, M=7, Generic Rock Boore, Joyner, Fumal Campbell Abrahamson and Silva Sadigh et al. Peak Acceleration (g) NGA 2006, SS, M=7, Vs=760 Campbell and Bozorginia Chiou and Youngs Abrahamson and Silva Boore and Atkinson Distance (km) Distance (km) Went from ad hoc relationship development to unified approach Mutually agreed upon databases, technical bases & assumptions Epistemic uncertainties reduced and characterized Broad community consensus (removed points of contention) 25

26 NGA-East Follows up on original NGA project Previous lack of systematic, integrated evaluation of existing models and new data Approach Standard agreed upon assumptions Standard and complete database Development program first to scope project and bring in multiple agencies Cooperative agreement USGS in-kind participation in development project Currently doing preliminary work Technical Basis for assumptions Development of earthquake record database 26

27 M max Workshop M max is largest magnitude for a source Issue for area sources in CEUS for long return periods Limited technical basis due to lack of systematic, integrated evaluation of existing models and new data Follows best practices for seismic workshops Sensitivity study Foundation document compiled & sent to participants before workshop for review. Also downloadable at USGS. All key researchers sponsored, but open to anyone Results incorporated into USGS database 27

28 Key Seismic Zone Updates Northeast (NESZ) Charleston (CSZ) New Madrid (NMSZ) Eastern Tennessee (ETSZ) 28

29 SSHAC Guidelines Recommendations for PSHA: Guidance on Uncertainty and Use of Experts NUREG/CR-6372 Senior Seismic Hazard Analysis Committee (SSHAC) sponsored by NRC, DOE & EPRI Need practical recommendations on how to apply and how to update General framework but limited practical details Much has been learned in trying to apply SSHAC Yucca Mountain (two level 4s seismic and volcano) PEGASOS (level 4) EPRI (level 3) 29

30 3.1 Random Vibration Theory 3.2 Site response methods Multiple methods accepted in NUREG 6728 Theoretical framework but few details Only recently used Implementation differs between practitioners Focus on better Active Projects understanding Multiple modeling tools currently in use Non-linear, SHAKE, and RVT methods Comparison of methods Developing public RVT software with PEER 30

31 Tsunami Hazard Research Collect existing data Investigate seismic sources Map past landslides Examine past landslides in geological context Model past landslides Map areas for potential future slides 31

32 Data Collection 32

33 Past Landslides 33

34 Past Landslides 34

35 Tsunami Model of Slide Height (m) Distance (km) 35

36 Debris Thickness 36

37 Seismic Sources Puerto Rico 37

38 Generation and Propagation Modeling 38

39 US Tsunami Mapping? 39

40 NRC/USGS Collaborative Program NGA East Program Development Inter-plate M max workshops East Tennessee Seismic Zone Studies PSHA Epsilon values 40

41 Integrated PSHA & Site Response For each spectral frequency Find effects of all possible earthquakes, weight each by the likelihood will actually happen in a given year, combine the events 41

42 Integrated PSHA & Site Response For each spectral frequency What is the best method? When does it matter? How do we increase availability of software & knowledge? Integration of Site Response 42

43 NRC Research: CAV Filtering Cumulative Absolute Velocity Better predictor of damage than peak acceleration Removes quakes too short to cause damage Spectral Acceleration (g) 2 1 Mean Rock UHRS 1 E-6/yr Frequency (Hz) 43

44 Questions? 44