ML13066A625

Email from S. Wong, NRR to J. Mitman, NRR Draft Letter to FERC

ML13066A625
Person / Time
Site:	Oconee
Issue date:	11/17/2010
From:	Wong S Office of Nuclear Reactor Regulation
To:	Jeffrey Mitman Office of Nuclear Reactor Regulation
References
FOIA/PA-2012-0325
Download: ML13066A625 (3)

Text

Mitman, Jeffrey From: Wong, See-Meng Sent: Wednesday, November 17, 2010 11:15 AM To: Mitman, Jeffrey

Subject:

RE: draft letter to FERC OK, thanks.

n e...i..a .e From: Mitman, Jeffrey 1 fVt_

Sent: Wednesday, November 17, 2010 11:13 AM To: Wong, See-Meng

Subject:

FW: draft letter to FERC See-Meng, I don't believe you received this email. I have not reviewed it yet, but will try to get to it shortly.

Jeff From: Wilson, George v"*.

Sent: Wednesday, November 17, 2010 7:09 AM To: Mitman, Jeffrey; Coleman, Neil; Wescott, Rex; Stang, John; Persinko, Andrew; Scott, Catherine; Khanna, Meena; Sexton, Kimberly; Simon, Marcia Cc: Hiland, Patrick; Cunningham, Mark

Subject:

draft letter to FERC Please look at the draft letter and provide comments George Wilson USNRC Acting Deputy Director, Division of Engineering Mail Stop 012H2 301-415-1711 1 .'

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Mitman, Jeffrey From: Wilson, George Sent: Wednesday, November 17, 2010 7:09 AM To: Mitman, Jeffrey; Coleman, Neil; Wescott, Rex; Stang, John; Persinko, Andrew; Scott, Catherine; Khanna, Meena; Sexton, Kimberly; Simon, Marcia Cc: Hiland, Patrick; Cunningham, Mark

Subject:

draft letter to FERC Attachments: FERC Letter - ONS temporary walls word doc.docx Follow Up Flag: Follow Up Flag Status: Completed Please look at the draft letter and provide comments George Wilson USNRC Acting Deputy Director, Division of Engineering Mail Stop 012H2 301-415-1711 1

Mr. Daniel J. Mahoney, Director Division of Dam Safety and Inspections Federal Energy Regulatory Commission Office of Energy Projects

SUBJECT:

Oconee Intake Dike - External Flood Diversion Barrier

Dear Mr. Mahoney:

By letter dated, September 13, 2010, the Federal Energy Regulatory Commission (FERC) requested that the U.S. Nuclear Regulatory Commission (NRC), confirm that the temporary structure on the Oconee Intake Dike, is a beneficial or prudent feature of the Oconee Nuclear Station (ONS) Safe Shutdown Facility (SSF) protection project that adds to the interim flood protection of the SSF.

Duke provided the NRC staff with 2D modeling runs of the flooding inundation study utilizing the existing temporary intake dike wall.. Those model runs showed that there would be a reduction in the water level from approximately 19 ft. to 5.5 ft. at the SSF on the ONS site. It is noted that the SSF is currently protected by a 7.5 ft. wall; therefore the current wall provides protection for the SSF, in the above scenario. The SSF provides equipment for additional accident mitigation at the site. The present intake dike wall structure is not designed to be water tight and does not meet FERC's design criteria. There is no positive upstream cutoff water barrier and uplift was not analyzed in the stability analysis. Based on this information, there is not an absolute assurance that the intake dike wall structure will perform in a manner that the analysis predicts; however there is a good likelihood that the intake dike wall act as a flood diversion barrier as depicted in the 2D modeling run. The NRC staff agrees that if the intake dike wall performs the function of a flood diversion barrier then it is beneficial for an interim flood protection measure at the ONS.

If you have any questions, please contact me at (301)415-1711.

Sincerely, George Wilson, Dam Safety Officer Division of Engineering Office of Nuclear Reactor Regulation US NRC cc: Charles Wagner, FERC