ML040050112

Phase 3 SDP Analysis with Handwritten Notes

ML040050112
Person / Time
Site:	Arkansas Nuclear
Issue date:	12/12/2003
From:	NRC Region 4
To:
References
FOIA/PA-2003-0358
Download: ML040050112 (3)

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Phase 3 SDP Analysis Performance Deficiency.

ANO Unit 1 fire zone 99-M (North Electrical Switchgear Room) di 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 100-N, which is adjacent to fire zone 99-M Heat release rates of 200-500 kW'n fire modeling of duration and severity 0 )

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..1 I 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 (I\5?/

- Transformers->

- Ventilation Subsystems

Human Reliability Screening Analysis.

o 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 po er:

• Human error probability (HEP) estimates determined using NRC ASP methodology, INEEL/EXT-99-0041, "Revision of the 1994 ASP HRA Methodology (Draft)," January 1999.

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