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MONTHYEARML22112A0062022-04-20020 April 2022 (Public Version) Oconee SLRA - Final RCI 3.5.2.2.2.6-L ML21323A1152021-11-23023 November 2021 Subsequent License Renewal Environmental Review Requests for Additional and Subsequent Information - Enclosure ML18060A0282018-02-28028 February 2018 Noncurrence Process - Alternative to Codes and Standards ML16055A1882016-01-15015 January 2016 FOIA/PA-2016-0071 - Resp 3 - Interim, Continuing to Process Request. Part 2 of 2 ML16055A1872016-01-15015 January 2016 FOIA/PA-2016-0071 - Resp 3 - Interim, Continuing to Process Request. Part 1 of 2 ML15224A7792015-08-0707 August 2015 FOIA/PA-2015-0393 - Resp 2 - Final, Part 1 of 1 ML15162A0842015-06-11011 June 2015 GTCC Disposals at the Barnwell Low-Level Radioactive Waste Facility from 1998 to Present ML14135A4082014-05-0707 May 2014 FOIA/PA-2013-0213 - Resp 3 - Final, Group Letter D. Part 1 of 1 ML14058A0822014-02-0404 February 2014 Questions and Answers Related to the Oconee External Flooding Issue ML14058A0522014-02-0404 February 2014 Use of FERC Inundation Calculation Parameters ML14058A0502014-02-0404 February 2014 Questions and Answers Related to Oconee Flood Barrier ML14058A0492014-02-0404 February 2014 Site Adequate Protection Backfit Documented Evaluation ML14058A0212014-02-0404 February 2014 Request for Opinion on the Safe Shutdown Facility Added to the License Basis for the Oconee Units in an SER ML14058A0202014-02-0404 February 2014 Nancy Ssf Flooding URI Number 1 ML14058A0192014-02-0404 February 2014 TIA, Answers to Questions in Relation to Licensing Basis for Flooding for the Safe Shutdown Facility at Oconee Station ML14058A0152014-02-0404 February 2014 Site Adequate Protection Backfit Documented Evaluation ML14049A2872013-08-28028 August 2013 Meeting Feedback Form Meeting No. 20140354 ML16070A2882013-04-24024 April 2013 Jocassee and Keowee Dams, Breach Parameter Review, Dated April 24, 2013 (Redacted) ML13240A0162013-03-0606 March 2013 Report, Enclosure Oconee Nuclear Station Flooding Hazard Reevaluation Report ML13052A7852013-02-26026 February 2013 Flood Licensing Basis Evaluation Open Items ML13056A1052013-02-0606 February 2013 Comparison of Approaches for Calculating a Jocassee Dam Failure Frequency ML13052A7802013-02-0606 February 2013 Options for Revising Oconee Flood CAL Due Dates ML13052A7812013-02-0606 February 2013 Timeline - Summary of Events ML13052A7832013-02-0606 February 2013 Draft NRC Information Notice on Dam Failure Frequency in Probabilistic Risk Assessments ML13052A7872013-02-0606 February 2013 Justification for Continued Operation of Oconee Nuclear Station ML13056A1002013-02-0606 February 2013 Resolution of Oconee Flooding Issue ML13052A7862013-02-0606 February 2013 Jocassee Dame Failure Frequency Components ML12121A6382012-04-30030 April 2012 Response to Nuclear Regulatory Commission Standard Steam Generator Questions for Oconee Unit 3 ML12056A0522012-03-12012 March 2012 Enclosure 6 - List of Power Reactor Licensees and Holders of Construction Permits in Active or Deferred Status ML12003A0632011-12-16016 December 2011 Tornado and High Energy Line Break (HELB) Mitigation License Amendment Requests (Lars) - Responses to Request for Additional Information, Part 2 of 6 ML12003A0672011-12-16016 December 2011 Tornado and High Energy Line Break (HELB) Mitigation License Amendment Requests (Lars) - Responses to Request for Additional Information, Part 4 of 6 ML12003A0682011-12-16016 December 2011 Tornado and High Energy Line Break (HELB) Mitigation License Amendment Requests (Lars) - Responses to Request for Additional Information, Part 5 of 6 ML12003A0692011-12-16016 December 2011 Tornado and High Energy Line Break (HELB) Mitigation License Amendment Requests (Lars) - Responses to Request for Additional Information, Part 6 of 6 ML1131406132011-11-0101 November 2011 Enclosure 3 - Regulatory Enforcement Conference - Resubmittal of Supplement ML11279A2532011-10-0606 October 2011 NRC Pre-submittal Meeting - Proposed Tornado Mitigation Flowchart Revision 6 Oconee Nuclear Station, Units 1, 2, and 3 ML11279A2522011-10-0606 October 2011 NRC Pre-submittal Meeting- Proposed Turbine Building HELB Mitigation Flow Chart Revision 5 Oconee Nuclear Station, Units 1, 2, and 3 ML1101907492011-01-18018 January 2011 Enclosure 3 - List of Attendees ML1035103792010-12-17017 December 2010 NFPA 805 Transition Pilot Plant FAQ 08-0054, Revision 1 ML1026404582010-09-13013 September 2010 Enclosure 2 - Redacted Version of Request for Additional Information Re the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (2001 Edition) ML1035100122010-08-19019 August 2010 NRC Staff Response to NFPA 805 Transition Pilot Plant FAQ 08-0054, Revision 0 (Updated) ML1023705812010-08-19019 August 2010 NFPA 805 Transition Pilot Plant FAQ 08-0054 ML1019301982010-06-0909 June 2010 Onsite Ground/Surface Water Monitoring Questionnaire for Oconee Nuclear Station ML14058A0612010-04-13013 April 2010 Draft Oconee Nuclear Site Adequate Protection Backfit Documented Evaluation ML1019304602010-03-25025 March 2010 List of Historical Leaks and Spills at Us Commercial Nuclear Power Plants ML1019305442010-02-0808 February 2010 Ground Water Communication Supplemental Information Questions and Answers ML1100606662009-10-0909 October 2009 Photographs of Ssf Asw Leak and Piping Replacement Project Taken Between August 20, 2009 and October 9, 2009, by Oconee Resident Inspectors. Part 2 of 14 ML0927103442009-09-25025 September 2009 Site Visit Observation on 09/25/2009 by Joel Munday for Oconee ML1100404352009-09-15015 September 2009 Plant Issue Tracking Application; Plant Status Daily - Oconee Information for 09/15/2009 ML1100309332009-07-13013 July 2009 Congressional Staff Briefing: Monday July 13, 2009, 3:30 Pm, Room 2108 Rayburn Bldg; Topic: Follow-Up Questions Regarding Chairman'S June 17, 2009 Response Regarding a IP2 Buried Pipe Leak ML0909004332009-04-0606 April 2009 Enclosure 2 - Oconee Nuclear Station Regulatory Audit - Documents Reviewed 2022-04-20
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I Use of FERC Inundation Calculation Parameters Issue: Are the inundation study parameters that Duke presented in its 50.54(f) letter response appropriate for any future inundation study? Are the current parameters sufficient to compute the flood height that the Oconee units need to be protected against?Concern: The parameters developed were used for the licensing of Jocassee Dam with FERC as required by 18 CFR 12D. Although these parameters are appropriate for licensing the dam, they might lack the necessary margins required to satisfy the licensing criteria for external flood protection for the Oconee Nuclear Site.Agency Mission Statements:
The Federal Energy Regulatory Commission (FERC) mission statement is: "Regulate and oversee energy industries in the economic, environmental, and safety interests of the American public." The NRC mission statement is: "The mission of the NRC is to license and regulate the Nation's civilian use of byproduct, source, and special nuclear materials to ensure adequate protection of public health and safety, promote the common defense and security, and protect the environment." Oconee Nuclear Site Requirements:
The licensing basis for external flooding for Oconee follows a draft version of GDC-2 presented in the Federal Register Notice of July 11, 1967: "Those systems and components of reactor facilities which are essential to the prevention of accidents which could affect the public health and safety or to mitigation of their consequences shall be designed, fabricated, and erected to performance standards that will enable the facility to withstand, without loss of the capability to protect the public, the additional forces that might be imposed by natural phenomena such as earthquakes, tornadoes, flooding conditions, winds, ice, and other local site effects. The design bases so established shall reflect: (a) appropriate consideration for the most severe of these natural phenomena that have been recorded for the site and the surrounding areas and (b) an appropriate margin for withstanding forces greater than those recorded to reflect uncertainties about the historical data and their suitability as a basis for design." Regulatory Guide 1.59, "Design Basis Floods for Nuclear Power Plants", states that, "In addition to floods produced by severe hydrometerological conditions, the most severe seismically induced floods reasonably possible should be considered for each site. Along streams and estuaries, seismically induced floods may be produced by dam failures or landslides. " .. "Flood conditions that could be caused by dam failures from earthquakes should also be considered in establishing the design basis flood." The most severe impact must be considered for dam failure with an appropriate margin to withstand higher forces.
FERC Guidance on Dams: In conducting dam break studies, FERC suggests 1 for rockfill dams that an average breach width of between one and five times the height of the dam should be used. The time-to-failure should be within 0.1 hrs (6-minutes) to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. The guidance goes on to state, "For a worst-case scenario, the average breach width should be in the upper portion of the recommended range, the time to failure should be in the lower portion of the range, and the Manning's "n" value 2 should be in the upper portion of the recommended range. In order to fully evaluate the impacts of a failure on downstream areas, a sensitivity analysis is required to estimate the confidence and relative differences resulting from varying assumptions." To account for high degree of uncertainty, FERC recommends that the upper breach width along with shorter times be adopted assuming that the dam fails catastrophically.
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Conclusion:==
In its response to the 10 CFR 50.54(f) letter, Duke argued that the parameters that were used in the FERC inundation study were conservative.
However, NRC review of the FERC regulations and quidance shows that the parameters are not conservative.
The 575-ft breach width chosen by Duke is at the lower end ot the guidance range, or less than twice the height of the dam. The time-to-failure chosen by Duke of 4-hours is four times higher at the less conservative end of the maximum time of one hour. To account for the high degree of uncertainty, FERC recommends a higher breach width and lower time-to-failure.
1 Federal Energy Regulatory Commission, FERC Engineering Guidelines, Appendix Il-A, "Dambreak Studies", October 1993.2 Manning's equation is an empirical formula which measures flow velocity across the open channel created by the dam breach. The "n" factor is an empirical factor which represents roughness of the channel which is inversely proportional to the velocity.