ML12041A447

E-mail from G. Wilson, NRR to G. Wilson, NRR Et Al. (Shakecast Report)

ML12041A447
Person / Time
Site:	North Anna
Issue date:	08/24/2011
From:	George Wilson Office of Nuclear Reactor Regulation
To:	Boger B, Grobe J, George Wilson Office of Nuclear Reactor Regulation
References
FOIA/PA-2011-0357
Download: ML12041A447 (3)

Text

• __. U From: Wilson. Georoe To: Wilson, George; Groe, Jack; Boger, Bruce; Leeds. Eric; Ruland. William; McGintv. Tim; Lund. Louise; Pruett.

Troy; Lubinski, John; Wiggins, Jim; Dapas. Marc; McCree. Victor; Croteau, Rick; Jones. William; Brown.

Frederick; Gitter. Joseoh; Howe, Allen; Evans, Michele; Holian. Brian; Skeen. David; Galloway. Melanie; Cheok.

Michael; Nelson. Robert; Bahadur. Sher; Andersen. James; Dean Bill; Virgilio. Martin; Borchardt. Bill; Weber, Michael; Johnson, Michael; Holahan. Gary; Merzke, Daniel Cc: Ui Yong; Karas. Rebecca; Khanna. Meena; Munson. Clifford; Kammerer. Annie; Manoly. Kamal

Subject:

RE:

Date: Wednesday, August 24, 2011 1:53:29 PM Attachments: shakecast report nrc.odf This email contains an update of the ground motion estimate of the North Anna site based on the latest USGS data. The current best estimate of the PGA for the rock is 0.2g, which contains significant uncertainty. The SSE of the North Anna NPP is 0.12g.

It should be noted that the initial estimate from. Version 1 of the ShakeCast report was based on very preliminary information. The present Version 6 is attached. As information has become available,- the ground motion estimate, particularly the location and magnitude of earthquake has become better constrained. This is due to aftershock information and intensity information from the USGS "Did You Feel It?" system, which provides a level of "ground truthing". We just spoke to the USGS and they think that the numbers have stabilized, however we will provide further updates as we receive them.

The underlying data comes from something called a ShakeMap, which is the information that the USGS puts out to the public. North Anna is on hard rock which may further amplify the incoming motions. It appears that the are many indications that the SSE was exceeded.

Currently, the licensee is retrieving their seismic recording instrumentation. However, we do not yet know the type and quality of the recording data that will be available to the NRC. Information from the NPP will be used to evaluate the USGS estimates of ground motion and to compare with FSAR design basis. The data will also inform the staff if additional analysis is needed.

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Message -----

From: Wilson, George Sent: Wednesday, August 24, 2011 10:35 AM To: Grobe, Jack; Boger, Bruce; Leeds, Eric; Ruland, William; McGinty, Tim; Lund, Louise; Pruett, Troy; Lubinski, John; Wiggins, Jim; Dapas, Marc; McCree, Victor; Croteau, Rick; Jones, William; Brown, Frederick; Guitter, Joseph; Howe, Allen; Evans, Michele; Holian, Brian; Skeen, David; Galloway, Melanie; Cheok, Michael; Nelson, Robert; Bahadur, Sher; Andersen, James; Dean, Bill; Virgilio, Martin; Borchardt, Bill; Weber, Michael; Johnson, Michael; Holahan, Gary Cc: Li, Yong; Karas, Rebecca; Khanna, Meena; Munson, Clifford; Kammerer, Annie; Manoly, Kamal

Subject:

FW:

The following attachment includes the following The latest shake cast report from the USGS - this shows that the peak ground motion was .16g The Design for North Anna is .12g The North Anna Spectral curve from Numark/FSAR and spectral curve from earthquake. You can see where the data from the earthquake exceeds design curve above 10hz.

The next pictures shows the same curve outlay from the IPEEE submittal..

Reg Guide 1.166 for the after earthquake guidance.

This info is still draft and preliminary.

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From: GEORGE.WILSON@NRC.GOV [1]

/77

Sent: Wednesday, August 24, 2011 9:44 AM To: Wilson, George

Subject:

H-RU`SNRcl ShakeCast Report Magnitude 5.8 - VIRGINIA Version 6 Origin Time: 2011-08-23 17:51:04 GMT Created: 2011-08-24 15:11:29 GMT Latitude: 37.9360 Longitude: -77.9330 Depth: 6.0 km These results are from an automated system and users should consider the preliminary nature of this information when making decisions relating to public safety. ShakeCast results are often updated as additional or more accurate earthquake information is reported or derived.

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• - MMI level may extend beyond map boundary; some facilities may not appear on the map due to space restriction