ML14058A030

NRR ET Meeting on Oconee Flood Protection and the 10 CFR 50.54(f) Response

ML14058A030
Person / Time
Site:	Oconee
Issue date:	10/23/2008
From:	Office of Nuclear Reactor Regulation
To:
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References
FOIA/PA-2012-0325
Download: ML14058A030 (7)

Text

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""=I In nf6~ d'nOconee Flood Protection and the10 CFR 50,54() ResponseNRR ET MeetingOctober 23, 2008October 23, 2008 fri , i,, I knlxt -1 S caiuse )ensi ve(Ij2S.NRC

=naIUnatNifectil h~opfa and ihg &avironmw"I-Objectives Purposes-Summarize the licensee's responses

-Discuss the staff's evaluation

-Receive ET feedback on the merits ofproposed key messages to the licenseeOctober 23, 20082 unfici ausenai ensivUSNRC Ia Infar,Nwcing People and Ow Envronment

Background

, NRC inspections in 1994 and 2005Issues regarding Oconee external flooding licensing basis, FERC-required inundation study (1992)-Site flood height as high as 16.8 fp.et, Unclear demonstration of flood height foradequate protection s Underestimated Jocassee Dam failurefrequency

@ 10 CFR 50.54(f) letter to Duke to addressflooding concernsOctober 23, 20083

( USNRCP*fiq~an P"oPke : te £acwomwuld Principal 10 CFR 50.54(f Questions Regarding Oconee Flood1. Explain the bounding external flood hazard atOconee and the basis for excluding consideration ofother external flood hazards, such as those described in the Inundation Study, as the bounding case.2. Provide your assessment of the Inundation Study andwhy it does or does not represent the expected floodheight following a Jocassee Dam failure.3. Describe in detail the nuclear safety implications offloods that render unavailable the SSF andassociated support equipment with a concurrent lossof all Alternating Current power.October 23, 2008 Official ly -Se it e 4x,-~f'rnal Info 't~o iLicensee's ResponseWritten response-Assessed inundation levels based on current drought conditions

-Committed to increase current flood walls by 2.5 feet byFebruary 2009-Proposed further analysis by February 2010-Relied heavily on test and inspection of dam to support lowfrequency assumptions

-Asserted that seismic failure is "not credible"

-Asserted that other dam failure modes (i.e., overtopping)

"notcredible"

@ Oral response-Stated that watertight doors could be procured for the SSF-Stated that SSF walls can accommodate the impact of a 16.8foot floodOctober 23, 2008 0 ff'IUse -Sen sve 5Intr Inora ' n

(-ýUS.NRCC In omtReview of Licensee's Response@ Interim continued operation acceptable if:-Licensee commits to water management of Jocassee Lakelevels-Licensee addresses SSF availability

1. Insufficient basis for final resolution-current and future-Limited scope> Lack of adequate seismic analysisLack of a probable maximum precipitation (PMP) analysis-Inadequate dam failure modelingTime of failure> Size of breachAnalysis model-Inadequate probabilistic argumentOctober 23, 20086 I I?megdteEzRC Inm rngProposed Key Messages For November 5, 2008Meeting with Licensees Interim continued operation acceptable if:-Licensee commits to water management of Jocassee Lake levels-Licensee addresses SSF availability e Insufficient basis for final resolution-current and future-Limited scope> Lack of adequate seismic analysis> Lack of a probable maximum precipitation (PMP) analysis-Inadequate dam failure modeling> Time of failure> Size of breach> Analysis model-Inadequate probabilistic argument.SSF improvements

-Scope, timing, and commitment unclear.Emphasis on timely resolution

.Letter conveying these concerns will be issued by November 21, 2008October 23, 20087