ML053290025
| 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: |
| References | |
| Download: ML053290025 (16) | |
Text
1 ONS Tornado Mitigation Methodology NRR Presentation November 14, 2005
2 ONS Tornado Mitigation Introduction Review of project objective Status of Tornado Method Changes based on Duke review Details not previously discussed Summary
3 ONS Tornado Mitigation Review Objective Develop and submit method Develop report documenting compliance with methodology Incorporate method and report into UFSAR by reference
4 ONS Tornado Mitigation Project Status Method development nearing completion Site review of draft method-complete Incorporation of site comments-complete
5 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
6 ONS Tornado Mitigation Methodology
Scope of Method
Reflects current configuration
Largely deterministic
Incorporates risk insights
Wind and P
Concurrent events
7 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
8 ONS Tornado Mitigation Changes Content Include TDEFW as defense-in-depth Continuity Available for most likely tornado scenarios
9 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
10 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
11 ONS Tornado Mitigation Additional Details Reliability and availability Per maintenance rule ONS maintenance rule expert panel establishes criteria based on PRA and expert judgment
12 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.
13 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
14 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
15 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
16 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