ML033020148
| ML033020148 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 10/10/2003 |
| From: | - No Known Affiliation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2003-0358 | |
| Download: ML033020148 (3) | |
Text
Phase 3 SDP Analysis Performance Deficiency ANO Unit 1 fire zone 99-M (North Electrical Switchgear Room) did not meet regulatory requirements for separation of electric cables and equipment of. redundant trains of systems necessary to achieve post-fire safe shutdown, and there was lack of adequate procedures for manual actions to achieve post-fire safe shutdown following a fire in fire zone 99-M (or other identified fire zones equivalent to 99-M)
Assumptions Red train cables are not protected with one-hour rated barrier, and are not separated from the Green train cables by a minimum of 20 feet distance free of intervening combustibles No automatic fixed fire suppression system Ionization detection system provides alarm in Main Control Room Credit for fire brigade response and arrival at fire zone 1 00-N, which is adjacent to fire zone 99-M Heat release rates of 200-500 kW in fire modeling of duration and severity 49
Integrated Assessment of Fire-induced CDF Fire Risk Equation:
FCDF =F.*Sf*Pl *P2*P3 where:
F. = Fire ignition frequency of ignition source Sf = Severity factor for a challenging fire P1 =
Probability of automatic fire suppression system being unavailable P2 =
Failure probability of manual suppression by fire brigade P3 =
Conditional core damage probability (CCDP), with or without recovery actions Identified Ignition Source Scenarios Electrical Switchgear Cabinets L Transformers Ventilation Subsystems
Human Reliability Screening Analysis Categories of Important Operator Recovery Actions Manual alignment of emergency feedwater to the steam generators Restoration of service water to affected diesel generators Isolation of letdown flow and inventory control Local start of a diesel generator without dc control power Human error probability (HEP) estimates determined using NRC methodology, INEEUEXT-99-0041, "Revision of the 1994 ASP HRA Methodology (Draft)," January 1999.