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 2008

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History •  Atomic Energy Commission (1954) •  Energy Reorganization Act of 1974

–  Department of Energy •  Nuclear weapons, promotion of nuclear power, care of low-

level 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

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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

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Organization Congressional

Oversight

Existing and New Reactor

Licensing

Yucca Mountain

Nuclear Facility Research

Presidential Appointees

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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

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New Regulatory Guide 1.208 •  “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

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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

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For each spectral frequency

+ + =

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For each spectral frequency

+ + = Chapter 2 Earth Science & Natural Hazards

Chapter 3 Earthquake Engineering

Cha

pter

4 In

tern

atio

nal A

ctiv

ities

Cha

pter

5 R

egul

ator

y G

uide

s

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For each spectral frequency

+ + = 2.3

2.4

2.6 2.7

3.1 3.2

2.8 2.10

2.2 2.5

2.9

3.33.43.5

3.6 3.7 3.8 3.11 3.13 3.9

3.10 3.12

Integrated Planning for Multidisciplinary work

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For each spectral frequency

+ + = 2.3

2.4

2.6 2.7

3.1 3.2

2.8 2.10

2.2 2.5

2.9

3.33.43.5

3.6 3.7 3.8 3.11 3.13 3.9

3.10 3.12

Active (07)

Upcoming (08)

Monitoring (09+)

Awaiting NGA (09+)

Long term (09+)

Long-Term Planning of current and future projects

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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

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•  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

Workshops and “Next Generation” approaches

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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

Incoherency Research

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Scattering

•  Function of distance and frequency

•  Function of material hardness?

•  Only one hard

rock site (w/ multiple events)

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Pinyon Flat Seismograph Array in Plan View

arrows show seismograph locations

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Example of Set of Array Data

Anomalous records were removed (See the funny red one?)

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Updated ITF Model from 12/06 “Common Understanding”

Frequency (Hz)

Coh

eren

cy

Phase angles of Fourier spectra stay coherent

Phase angles of Fourier spectra

are random

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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

Z

Y

CIS

SCVASB

150'

150'l

l lX

4011 5

NodeNumber Location401 Base of Steel Containment Vessel406 Low on Steel Containment Vessel417 Top of Steel Containment Vessel417out Steel Containment Vessel Outrigger1 Foundation of Auxiliary Shield Building80 Low on Auxiliary Shield Building80mc Low on Auxiliary Shield Building Mass Center120 Top of Auxiliary Building120out Top of Auxiliary Building Outrigger120mc Top of Auxiliary Building Mass Center310 Top of Shield Building310out Shield Building Outrigger5 Base of Containment Internal Structure535 Low on Containment Internal Structure535mc Low on Containment Internal Structure Mass Center538 Top of Containment Internal Structure538out Top of Containment Internal Structure Outrigger538mc Top of Containment Internal Structure Mass Center

l

l

l

l

l

401

406

417 l

80

310 l

417out

120mc

120out

310out

65'

1

l120

-20'

-10'

l5

l75'-10'

-10'

535

538out

535mc

538mc

80mc

-20'

-10'

538

-10'-10'

75'

l

l

l

l

l

l

l

l

SCV

ASB

CIS75'

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Implementation in SSI

Cross correlation of every foundation node point using

incoherency matrix based on ITF

(includes non-diagonal

elements)

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Free-Field vs. SSI and Incoherency

Response Spectra, Foundation, x-Direction

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0.1 1 10 100

Frequency (Hz)

Spec

tral

Acc

eler

atio

n (g

)

SSI, Incoherent FIM, x-direction

Fixed Base, x-direction

ITF & SSI

Horizontal Motion

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Impact of Incoherency in SSI

Response Spectra, Foundation, x-Direction

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0.1 1 10 100

Frequency (Hz)

Spec

tral A

ccel

erat

ion

(g)

SSI, Coherent, x-direction

SSI, Incoherent, x-direction

SSI, Incoherent FIM, x-direction

Fixed Base, x-direction

Horizontal Motion

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Vertical Translation & Rocking Transfer Functions

Rock Site, 150x150 fdn, Vertical & Rocking

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 10 20 30 40 50 60 70 80Frequency

Inco

here

ncy

Tran

sfer

Fun

ctio

n

CLASSI Vertical Translation CLASSI Translation due to RockingSASSI Vertical Translation SASSI Translation due to Rocking

KEY POINT:

Incoherency increases rocking and rotation in SSI

Is not accounting for incoherency really

conservative?

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For each spectral frequency

+ + = 2.3

2.4

2.6 2.7

2.8 2.10

2.2 2.5

2.9

Active (07)

Upcoming (08)

Monitoring (09+)

Awaiting NGA (09+)

Long term (09+)

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)

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NGA-East Before NGA-West After

1997 Attenuation Relations, SS, M=7, Generic Rock

0.01

0.1

1

1 10 100 1000Distance (km)

Peak

Acc

eler

atio

n (g

)

Boore, Joyner, Fumal

Campbell

Abrahamson and Silva

Sadigh et al.

NGA 2006, SS, M=7, Vs=760

0.01

0.1

1

1 10 100 1000Distance (km)

Peak

Acc

eler

atio

n (g

)

Campbell and BozorginiaChiou and YoungsAbrahamson and SilvaBoore and Atkinson

•  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)

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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

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Mmax Workshop

•  Mmax 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

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Northeast (NESZ)

Charleston (CSZ)

Eastern Tennessee

(ETSZ)

New Madrid (NMSZ)

Key Seismic Zone Updates

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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)

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3.1 3.2

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

understanding

•  Multiple modeling tools currently in use –  Non-linear, SHAKE, and RVT

methods –  Comparison of methods –  Developing public RVT

software with PEER Active Projects

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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

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Data Collection

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Past Landslides

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Past Landslides

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Tsunami Model of Slide H

eigh

t (m

)

-20

-1

0

0

10

2

0

-200 -100 0 100 200

Distance (km)

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Debris Thickness

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Seismic Sources

Puerto Rico

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Generation and Propagation Modeling

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US Tsunami Mapping?

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NRC/USGS Collaborative Program

•  NGA East Program Development •  Inter-plate Mmax workshops •  East Tennessee Seismic Zone Studies •  PSHA Epsilon values

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Integrated PSHA & Site Response

Find effects of all possible earthquakes, weight each by the likelihood will actually

happen in a given year, combine the events

For each spectral frequency

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Integrated PSHA & Site Response

Integration of Site

Response

For each spectral frequency

•  What is the best method?

•  When does it matter?

•  How do we increase availability of software & knowledge?

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NRC Research: CAV Filtering

0

1

2

0.1 1 10 100Frequency (Hz)

Spec

tral A

ccel

erat

ion

(g)

Mean Rock UHRS 1 E-6/yr

•  Cumulative Absolute Velocity

•  Better predictor of damage than peak acceleration

•  Removes quakes too short to cause damage

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Questions?