ML14058A041
| ML14058A041 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/25/2010 |
| From: | Jeffrey Mitman Office of Nuclear Reactor Regulation |
| To: | Ferrante F Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2012-0325 | |
| Download: ML14058A041 (9) | |
Text
Mitman, Jeffrey From: Mitman, Jeffrey I\ (l (L Sent: Tuesday, May 25, 2010 6:18 PM To: Ferrante, Fernando
Subject:
FW: OUO/Security-Related Information - Briefing to Commissioner Apostolakis on Oconee External Flooding Event Attachments: Commr Briefing on Oconee External Flooding Event (2).ppt FYI From: Khanna, Meena Sent: Tuesday, May 25, 010 4:26 PM To: Wescott, Rex; Coleman, Neil; Uribe, Juan; Hoang, Dan; Mitman, Jeffrey; James, Lois; Kulesa, Gloria; Shoop, Undine Cc: Stang, John; Wilson, George
Subject:
FW: OUO/Security-Related Information - Briefing to Commissioner Apostolakis on Oconee External Flooding Event Just an fyi... here are the slides that we used at Commr. Apostolakis' briefing today on Oconee External Flooding... itwent really well and I thank all of you who supported John and I with the briefing!
George and I will schedule a safety review group meeting as well as an oversight group meeting in the very near future to get everyone up to speed on where we are at with this issue so that everyone is on the same page.
- Thanks, Meena From: Khanna, Meena i "U.
Sent: Monday, May 24, 2010 7:14 PM To: Sosa, Belkys; Snodderly, Michael Cc: Skeen, David; Glitter, Joseph; Stang, John
Subject:
Briefing to Commissioner Apostolakis on Oconee External Flooding Event Belkys and Mike, Since it got a bit late in the evening, Dave Skeen requested that I send you the slides that we will be presenting to Commissioner Apostolakis at Tuesday's briefing at 10:00 am on the Oconee External Flooding Issue. We will also bring pictures and diagrams to the briefing. Please note that this information is OUO/Security-Related Information.
Ijust dropped off copies of the slides and pictures with Margie as well.
Please contact us if you have any questions.
- Thanks, Meena Khanna, Branch Chief Mechanical and Civil Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation (301)415-2150 meena.khanna@nrc.aov D-35
2U.S.NRC UNITED STATES NUCLEAR REGULATORY COMMISSION ProtectingPeople and the Environment Commissioner Briefing on Oconee External Flooding Issue May 25, 2010 1
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Background
In2006, while performing a Reactor Oversight Process (ROP) evaluation, the staff questioned Duke's maintenance of the flood protection barrier for the standby shutdown facility (SSF).
@Based on staff's concerns with external flooding at the Oconee site, pursuant to 10 CFR 50.54(f), the NRC issued a request for information on August 15, 2008.
e The licensee responded September 26, 2008.
- Inresponse to this letter, Duke stated that this inundation will lead to core damage, containment failure, and loss of spent fuel pool cooling at all three units, ifno mitigating actions are taken.
s Duke's response did not provide sufficient information to demonstrate that the Oconee site had adequate protection from an external flooding event.
e NRC staff conducted numerous closed meetings and telecons with Duke to achieve a common understanding of the technical issues.,
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1'oteka Peopl and IeEwmiiumwnl s NRC then issued a letter on April 30, 2009, requesting additional information on Oconee external flooding issue.
s Duke provided a response on November 30, 2009.
o NRC staff determined that although Duke provided a more accurate estimate of flooding caused by failure of Jocassee Dam, additional information was still needed.
a The NRC issued another round of questions on January 29, 2010.
s Duke provided a partial response on March 5,2010 and is on track to submit afinal response by the end of June 2010.
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VU.S.NRC Interim Compensatory h :,d aten;asalEavigrent Measures Being Taken Duke submitted letter to staff on January 15, 2010, committing to implement interim compensatory measures to ensure that Oconee site will be adequately protected from external flooding events prior to final resolution.
- Region II,with NRR support, will conduct an inspection of the interim compensatory measures during the week of June 7,2010.
- Quarterly NRC/Duke senior management meetings are held to continue effective communications.
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3jU,.SNRC Potential Failure of Jocassee Dam UN111D Rk(,ULA70KYM CUML~UCLI.AR riOKJ' Nkicbit ltple sad tke Eiwiramnent The most likely failure scenario for the Jocassee Dam isa piping failure near the west abutment.
Ifdam failure occurs, the Oconee site could be inundated within 3hours.
Duke did not address aJocassee Dam random failure and the resulting inundation of the Oconee site when itwas licensed in1973.
- Probable maximum precipitation/probable maximum flood (i.e., overtopping of the dam) and seismic considerations were reviewed by the staff and found acceptable during original licensing, W~S.R-ate0F !ma~j 5
2UNRC Flood Effects on Oconee Site
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UN MEFAUN l'rvNectiqgiop Ind tke Emiwromrent 18.5 ft of water (based on latest model) will result inunavailability of equipment for accident mitigation.
- Loss of Keowee hydro-generators, which are emergency AC onsite power supplies
- Switchyard would be unavailable, which isoffsite AC power source.
o Renders all pumps and valves with AC motors unavailable.
- Loss of emergency core cooling system and emergency feedwater pumps inturbine building basement for all three units.
- Normal and alternate methods for providing reactor coolant makeup, decay heat removal, and associated power to shutdown all three Oconee units will be unavailable.
Leaves only the SSF to mitigate the flooding event and to provide cooling to the reactor coolant pump seals.
- The SSF would also be lost due to flooding waters of approximately 18.5 ft., since presently only protected by 7.5 ft. wall.
- With loss of all equipment, flooding inundation would lead to core damage, containment failure and loss of spent fuel pool cooling at all three units within approximately 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br />.
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DIU.S.NRC Generic Failure Rate Evaluation VNIMTWEArIUCLLA RIG(ULA UKY LO&(N1IV of Large Rockmfilled Dams
- Staff approach inderiving generic failure rate of large rock-filled dams:
- Assessment of overall US dam population for those with similar features to Jocassee Dam,
- Study of US dam performance information for failure events that may be applicable to this subset of overall population.
e Staff used two databases to obtain information about the population of dams inthe US.
- National Inventory of Dams (NIDs)
- National Performance of Dams Program (NPDP) e Staff estimated generic dam failure rate for large rock-filled dams to be 2.8E-4/dam-year.
e Literature review corroborated this conclusion.
, Duke intends to complete amore detailed failure rate evaluation specifically for the Jocassee Dam next year, which isbeing conducted by Utah State.
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~US*NRC Next Steps
@ Region II,with NRR support, will conduct an inspection of the interim compensatory measures (week of June 7, 2010).
e Duke to submit final responses to staffs questions regarding potential flooding by end of June.
s Staff iscompleting Adequate Protection Backfit Analysis.
s Staff plans to issue an Order inthe near term to confirm the compensatory measures, and Duke's schedule for the final resolution.
a Staff has entered this issue into RES Generic Issues Program.
@NRC/Duke Sr. management and staff meetings and telecons will continue to ensure effective communications.
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