ML070670331

Site Status, NuStart-NEI Seismic Workshop

ML070670331
Person / Time
Site:	Harris, Bellefonte, PROJ0740
Issue date:	03/01/2007
From:	Progress Energy Carolinas
To:	Office of Nuclear Reactor Regulation
References
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Download: ML070670331 (20)

Text

1 Progress Energy Harris Site Status NuStart-NEI Seismic Workshop March 1, 2007 2 Harris Project Summary*Existing Harris Nuclear Plant (HNP Unit 1) located 20 miles SW of Raleigh, NC*Two new AP1000 Units (HAR 2 and HAR

3) are planned adjacent (North) of HNP Unit 1*Site Investigation performed April through December 2006*PSHA and SSE work ongoing*COLA submittal in late 2007 3 Harris Site Location 4 Harris Location of New Units HAR 3 HAR 2 South 5 Harris Geotechnical Boring Layout SiteView NI 6 Harris Geotechnical Investigation Summary 4 Pairs of Profiles (depth < 100 ft)

SASW Surveys (Vs) 5 Profiles (depth < 70 ft)

MASW Surveys (Vs) 2 Boreholes (~200 ft depth)

Downhole Logging (Vp and Vs) 7 Boreholes (~150-200 ft depth)

P-S Suspension Logging (Compression and shear wave velocity [Vp and Vs])

~3200 Feet Seismic Refraction Surveys (Vp) 20 Groundwater Monitoring Wells

-50 at AP1000 Structures

-18 General Characterization

-15 at CTs and Conveyance Soil & Rock Borings 7 Harris Existing Subsurface Profile (Typical)

HAR-3 HAR-25 -20'0 -10'0 -10'15 -40'Top of Sound Rock10 -25'Top of Weathered Rock

-Transition Zone from Residual Soil

to Sound Rock0 -25'Residual Soils-Reddish Brown.

Typically lean clays (CL), sandy

silts (ML) and silty sand (SM) 8Harris -Unit 2 Fence Diagram with S-Wave Velocity Profiles 9Harris -Unit 3 Fence Diagram with S-Wave Velocity Profiles 10Harris -Unit 2 -S-Wave Velocity Profiles -Adjusted Elevations 11Harris -Unit 3 -S-Wave Velocity Profiles -Adjusted Elevations 12 Harris Rock Shear Wave Velocity*Shear Wave Velocity (V S) below Reactor Island Basemat Elevation (220 feet above MSL) -

based on 7 suspension logging profiles to depth

of ~200 feet bgs.

Standard Deviation Average Vs (fps)Unit 981 6,079 HAR-3 779 6,227 HAR-2 13 Harris Preliminary Construction Plans

• Plant Site Grades-Establish Plant Grade at Elevation = 260 feet.-Establish Nuclear Island Basemat Subgrade on Competent Rock at Elevation = 220 feet.

• Nuclear Island

-HAR-2: Rock Excavation (~1H:2V) to basemat subgrade.-HAR-3: Plan to excavate as so il (~2H:1V) to basemat subgrade.

Overexcavate clay seams at basemat subgrade, backfill/grout with concrete fill.

• Other Structures

-HAR-2: Excavate to Competent Rock and place Engineered Backfill (typically only 5 to 10 feet needed).-HAR-3: Overexcavateand place Structural Backfill (up to 30 feet needed), OR construct deep foundations (caissons). To be

finalized during detailed design.

14 Harris Site Seismicity*Site sits in a region of relatively low seismicity*Sources related to Charleston, East

Tennessee, Giles

County, and Central

Virginia at distances >

~ 100 km contribute to site hazard Charleston East Tennessee Central VirginiaHarrisSite Giles County 15 Harris Regional Physiographic Setting 16 Harris Site PSHA*Use UCSS (Vogtle) update of Charleston seismic source-Overlay reoccurring Charleston m b> ~6.5 earthquakes-Limit M max to m b6.5 for EPRI-SOG Charleston sources to prevent double counting*Use EPRI-SOG expert team assessments for all other seismic sources-No adjustments in rates needed-Minor adjustments in M max and source combinations 17 Harris Site PSHA (Cont'd)*Use EPRI (2004) Ground Motion Models*Use EPRI (2006) (G1.3) Aleatory Variability (Sigma)*Consider use of EPRI (2006) CAV filter (G1.2)-Not expected to produce a large change in hazard-Implementation will incorporate site response 18 Harris Site Geology*Site sits in Durham subbasinof the Deep

River basin*Approximately 5,000 ft of Triassic sediments*Shallow sediments consist of interbedded

siltstones and sandstones

• V S 4,000-5000 ft/sec at foundation level, quickly rising to 6,000-7,000 ft/sec 19 Harris Site Response*Compute amplification of Triassic sediments using NUREG/CR 6728 method 2B*Shallow velocity profile based on site data to a depth of ~200 ft*Deeper profile based on nearby deep bore hole and refraction lines 20 Harris Site SSE Ground Motions*Use performance-based ASCE 43-05 methodology*Define SSE at outcrop of weathered Triassic rocks -elevation ~250 ft*Simultaneously compute motions at foundation level -elevation 220 ft