ML100060063

Licensee Slides from 1/5/2010 Meeting Regarding Shoreline Fault Regarding Diablo Canyon Power Plant, Unit Nos. 1 and 2

ML100060063
Person / Time
Site:	Diablo Canyon
Issue date:	01/05/2010
From:	Pacific Gas & Electric Co
To:	Office of Nuclear Reactor Regulation
Wang, A B, NRR/DORL/LPLIV, 415-1445
References
Download: ML100060063 (77)

Text

Shoreline Fault Evaluation Lloyd Cluff & Norm Abrahamson PG&E Geosciences 2009 progress briefing January 5, 2010 Methods used to estimate and constrain Shoreline fault:

Location Variations in seismicity alignment Geophysical profiling Mapping offshore wave-cut platforms Style of faulting Constraints on activity (fault slip-rate)

Length and rupture area Magnitude of potential earthquakes Ground motions Primary surface fault rupture; secondary fault deformation?

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DCPP (PG&E 1988)

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J. Hardebeck (USGS)

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Alignment of small earthquakes (M < 1 to 3.5) z ult i fa sgr Ho one

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Nov 2008 Preliminary Evaluation 2008 Assumptions y Length and Width Full length of the seismicity alignment (25 km)

Depth of Seismicity of 12 km Maximum magnitude: M=6.5 y Distance offshore DCPP 1 km Results y Deterministic (84th percentile) ground motions lower than 1991 LTSP ground motion

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Issues Identified in 2008 Length and Width y Does Shoreline fault zone extend to Hosgri?

y How far does the Shoreline fault zone extend to the SE?

y Is the fault zone continuous over its length Fault zone may be broken into small discontinuous segments Closest distance offshore DCPP y What is the distance offshore?

Activity Rate y Appear to be low, but not well constrained

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.fugro.com Seismicity Alignment Cross-Sections

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No rt h ern Ce ntr al So uth e rn Point Buchon area with respect to Hardebecks (2009) microseismicity lineament pparent segmentation

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2008 aeromagnetic survey tracklines along the central California Coast Ranges

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New Fill In DCPP 2009 USGS Marine Survey Area New

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Blue = tracks of high resolution marine seismic reflection and magnetic data were collected at 800 m spacing.

Red = additional marine magnetics tracks for a net 400 m spacing (Watt et al., 2009).

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oundaries of 2009 helicopter magnetic survey flown with 150 m line spacing at a nominal altitude of 100 m.

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ded area offshore

t. Buchon ected in 2007 track lines = areas ected in 2009 2009 atial resolution 2007

= water depths < 50 m

= water depths > 50 m DCPP 2009

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. Buchon ultibeam Bathymetry llected as part of State Waters Mapping Program CSU Monterey Bay afloor Mapping Lab 2006-2007

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Tectonic strain gauge 120,000 Terrace

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.fugro.com DCPP

.fugro.com Paleoshorelines in Point Buchon area

Details of Geologic Map North of Point Buchon

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.fugro.com Geologic map of Point Buchon area N40W Faults

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50,000-year-old wavecut platform across the N40W Faults

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.fugro.com Evidence of No Faulting in Past 50 to 60,000 Years Seismic line PBS-32 across the N40W Faults

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Hosgri fault

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.fugro.com USGS Gravity data

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Hosgri Shoreline From Cluff and Olson/ San Luis Bay Cluff, 1985

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Summary of 2009 Study Results Microseismicity lineament defined by Hardebeck (USGS) a real feature During 2008 and 2009 we collected extensive geophysical data to characterize the Shoreline fault Shoreline fault zone is expressed in seafloor bathymetry and has 3 segments Central and southern segments of the Shoreline fault zone are coincident with the microseismicity lineament Microseismicity lineament diverges from the northern segment of the Shoreline fault zone and trends to the Hosgri fault zone with evidence of no surface faulting within at least 50,000 years The Shoreline fault is a vertical, strike-slip fault that extends to

~ 10 km depth Slip rate on the Shoreline fault zone is currently uncertain and is judged to be between 0.01 and 0.3 mm/yr The geomorphic expression of the Shoreline fault zone is dominated by differential erosion The Shoreline fault zone is 300 meters from the Intake structure and 600 meters from the Power Block

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Secondary Fault Rupture Given short distance (0.6 km) to power block, secondary fault rupture hazard is considered

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Lessons Learned From Investigating Strike-Slip Fault Ruptures Application of knowledge from experience in the investigation of historic and paleoseismic fault ruptures results in an understanding of the relationship between primary and secondary surface faulting hazards The threshold of surface faulting effects occur at

~ magnitude > 5.5 earthquakes Style of faulting is most important Near vertical Strike-slip faults result in simple narrow zones of surface rupture, except where the fault makes significant changes in strike direction Geometry of fault strike and changes in strike direction is very important

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Summary of First-Hand Experience with Strike-Slip Surface Fault Rupture Effects (primary fault rupture and secondary fault rupture) 1812 Bocono, Venezuela

• 1968 Borrego Mountain, CA 1855 Wairarapa, New Zealand

• 1968 Dashet-et-Bayez, Iran 1888 Hope, New Zealand

• 1979 ImperialValley, CA 1872 Owens Valley, Nevada

• 1979 Tabas, Iran 1906 San Andreas, CA

• 1979 Calaveras, CA 1939 Ercincan, Turkey

• 1976 Motagua, Guatemala 1940 Imperial Valley, CA

• 1992 Landers, CA 1942 Erbaa-Niksar, Turkey

• 1999 Izmit, Turkey 1943 Tosya, Turkey

• 1999 Duzce, Turkey 1944 Gerede-Bolu, Turkey

• 2001 Kunlun, Tibet 1954 Fairview Peak, NV

• 2002 Denli, Alaska 1958 Fairweather, Alaska

• 2006 Parkfield, CA 1966 Parkfield, CA

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trike-Slip Surface Fault Rupture n Andreas fault, Central California Offset stream channels

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.fugro.com 7.5, Rupture length otagua fault, (1m to 3m LL)

School

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1.5 m left slip

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.fugro.com Nojima fault Japan 1995

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jima fault rface fault rupture 95 Kobe Earthquake 6.9 rike-Slip ~ 2 m RL p-rate ~ 6 mm/yr secondary faulting

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pture Effects:

m P. faulting o sec. faulting ong shaking ll-built house hout damage

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Slip-rate ~10 mm/yr

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Right-slip 5.2 m

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.fugro.com Buildings close to fault not damaged by faulting

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Surface rupture length: 85 km Maximum riight-slip offset: 6 m

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= 7.3 L = 2 m to 6 m

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.fugro.com Landers Earthquake Kickapoo Fault

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.fugro.com Landers Earthquake 1992 Complex step-over between Johnson Valley and Homestead Valley faults

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.fugro.com Denali Fault Alaska

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. Cluff, Cluff, 1972

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Multiple Surface Rupture Events

< 1 m width of surface rupture L. Cluff, Cluff, 1972

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Denali Fault Paleo Surface Rupture Zone Width of Multiple Ruptures During Past 12 to 15 Surface Rupturing Events

~ 10 m

Cluff, Cluff, 1972

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Fault rupture released the M7.9 Denali fault earthquake picenter TAPS sitna Glacier fault Den ali f au lt Rupture length ~ 336 km Maximum right slip ~ 8.9 m To Rupture propagation speed ~ 4 to 6 km/sec ts ch un d a fa u lt

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.fugro.com L. Cluff 1973

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8.2 m luff, 2003

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.fugro.com L. Cluff 2003

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Denali Fault 2002, 8.5 m Strike-Slip surface rupture constrained within 1.5 m width, except at strike change where surface rupture effects were

~ 20 m wide L. Cluff 2003

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enali lose -up larged rface pture fects due fault rike ange

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surface rupture constrained within 1.5 m width

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.fugro.com trike-Slip Width of urface Rupture ~ 1 m 8.5 m

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Impacts at DCPP Ground Motion y Deterministic 84th percentile (margin approach) y Assumed Fault Rupture Models Central segment

{ Length = 8-9 km, width = 10-12 km

{ M = 5.9 - 6.0 Central & southern segments

{ Length = 14-15 km, width = 10-12 km

{ M = 6.1 - 6.25 y Distance from DCPP 0.6 km from powerblock

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.fugro.com Impacts at DCPP Secondary Fault Deformation y Probabilistic approach (PRA approach)

Follows methodology of Petersen et al (2004)

Straight segment offshore DCPP, reduces chance of secondary ruptures

{ Used below average range of probability of secondary rupture from empirical models given by Petersen et al (2004) which is based on all strike-slip faults Location of potential secondary rupture

{ Shale unit is a zone of weaker rock y Assumed slip-rate 0.01 to 0.3 mm/yr y Assumed Fault Rupture Models Same as for ground motion

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.fugro.com ASW pipes only safety-related SSC Annual Probability of impacted by secondary deformation Secondary Deformation at in shale unit Susceptible Segments of y 8 Dresser couplings ASW Pipes Secondary deformation at susceptible segments of ASW pipes Disp Central Central &

is very unlikely (cm) (M6.0) Southern (M6.25)

NRC allows exclusion of very unlikely events y For Yucca Mtn post-closure: exclude events with annual chance < 1E-8 1.0 4.2E 8.0E 1.3E-7 2.4E-7 y 10 CFR 63.342 Impact on DCPP seismic CDF is negligible 2.0 1.7E 2.3E 5.1E-10 6.9E-8 y Seismic CDF = 3.7E-5 (LTSP, 1988)

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Shoreline Fault Investigations in 2010 Activities:

Integrate USGS geophysical data with multibeam data Complete interpretations of Shoreline fault with respect to location, association with regional structures, segmentation, activity rate, and earthquake magnitude and surface faulting potential

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