ML053290025

Enclosure 2, Meeting Summary, Tornado Mitigation Methodology

ML053290025
Person / Time
Site:	Oconee
Issue date:	11/14/2005
From:	Duke Energy Corp
To:	Office of Nuclear Reactor Regulation
Olshan L N, NRR/DLPM, 415-1419
Shared Package
ML053290022	List: ML053290020 ML053290025 ML053290041
References
Download: ML053290025 (16)

Text

ONS Tornado Mitigation Methodology NRR Presentation November 14, 2005 1

ONS Tornado Mitigation Introduction Review of project objective Status of Tornado Method Changes based on Duke review Details not previously discussed Summary 2

ONS Tornado Mitigation Review Objective Develop and submit method Develop report documenting compliance with methodology Incorporate method and report into UFSAR by reference 3

ONS Tornado Mitigation Project Status Method development nearing completion Site review of draft method- complete Incorporation of site comments-complete 4

ONS Tornado Mitigation Project Status Transmit method by the end of Jan 2006 Complete final site review- Dec. 2005 Finalize V&V package- Beginning of Jan. 2006 PORC review of method- Mid Jan. 2006 NSRB review of method- End Jan. 2006 5

ONS Tornado Mitigation Methodology Scope of Method Reflects current configuration Largely deterministic Incorporates risk insights Wind and P TORMIS Concurrent events CEOG RCP seal model 6

ONS Tornado Mitigation Changes Process LAR will include UFSAR mark-ups Once NRC approves, Duke will classify implementation activities as NRC commitments using our corrective action program 7

ONS Tornado Mitigation Changes Content Include TDEFW as defense-in-depth Continuity Available for most likely tornado scenarios 8

ONS Tornado Mitigation Additional Details Inputs and Assumptions Power is lost to main feeder buses Safe shutdown equipment TDEFW (for most likely scenarios)

Station ASW HPI powered from Station ASW SWGR SSF ASW and Reactor Makeup Branch lines isolate on loss of power or manually per EPs 9

ONS Tornado Mitigation Additional Details Defense-in-Depth TDEFW for most likely scenarios Primary and alternate paths for design basis tornado SSF is primary path Station ASW/HPI is alternate path Note that SBO and Appendix R rely on single success path 10

ONS Tornado Mitigation Additional Details Reliability and availability Per maintenance rule ONS maintenance rule expert panel establishes criteria based on PRA and expert judgment 11

ONS Tornado Mitigation Additional Details Tornado Preparations Monitor tone alert radios During tornado warning, pre-stage operators A tornado warning means a tornado has been sighted by spotters or indicated by weather surveillance radar in the warning area.

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ONS Tornado Mitigation Additional Details Procedures Operating procedures developed to pre-stage for tornado APs and EPs developed to restore secondary heat removal and reactor makeup/RCPseal cooling Tech Support Center Guidelines developed to direct activities subsequent to 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> mission time 13

ONS Tornado Mitigation Summary Deterministic w/risk insights method Risk insights Wind and P TORMIS Concurrent events CEOG RCP seal model Consistent with SBO and SSE 14

ONS Tornado Mitigation Summary Defense-in-Depth SSF primary defense for design basis tornado Station ASW backup TDEFW good for most likely scenarios More extensive than SBO and App R 15

ONS Tornado Mitigation Summary Additional commitments Provide Station ASW/HPI control and indication power past 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> Refine guidance for cooling down when using Station ASW/HPI Develop guidelines for safe shutdown past 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> mission time 16