ML20115E021

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Responds to Preliminary Accident Sequence Precursor Analysis of 820613 Loss of Vital I&C Power Bus & Trip Event at McGuire Unit 1
ML20115E021
Person / Time
Site: McGuire Duke energy icon.png
Issue date: 07/09/1996
From: Mcmeekin T
DUKE POWER CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9607160064
Download: ML20115E021 (10)
v • d • e


Text

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11 l DukeIbwerCornpany T. C McMaus McGuint Nudear Generation Deparonent Vice President

. J2700Hagen ferryRoad(MG0lVP) (704)87S4800 Huntersville,NC28078D35 (704)8754809 Fax l

DUKdPOWER I

July 9,1996 U. S. Nuclear Regulator Commission

'ATI'N: Document Control Desk Washington, D. C. 20555

Subject:

McGuire Nuclear Station Docket No. 50-369 Response to the Preliminary Accident Sequence Precursor Analysis i

of Loss of Vital I&C Bus and Trip Event at McGuire Unit i 1 I

Thank you for the opportunity to provide comments on Oak Ridge National Laboratory's  ;

preliminary Accident Sequence Precursor analysis of the June 13,1982 loss of ac vital power bus and trip event at McGuire Unit 1.

For your consideration, Attachment A provides Duke's response on the subject analysis.

Also enclosed are Attachment I (ReactorTrip Initiated Core Damage Sequences With Nominal Main Feedwater Recovery) and Attachment 2 (Reactor Trip Initiated Core Damage Sequences Assuming No Main Feedwater Recovery), which are referenced by Attachment A.

If there are any questions regarding this response, please contact Kay Crane, McGuire Regulatory Compliance, at (803) 875-4306.

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Very Tmly Yours, '  !

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T. C. McMeekin, Vice President j McGuire Nuclear Station

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U.S. Nuclear Regulatory Commission '

Document Control Desk July 9,1996 Page 2 I l

cc: Mr. Victor Nerses  !

U. S. Nuclear Regulatory Commission l

Office of Nuclear Reactor Regulation

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Washington, D.C. 20555 Mr. S. D. Ebneter, Regional Administrator, Region II i U. S. Nuclear Regulatory Commission 101 Marietta St., N.W. Suite 2900 Atlanta,GA 30323 j

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Mr. Scott Schaeffer !

Senior Resident Inspector McGuire Nuclear Station l

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ATTACIIMENT A Response to the Preliminary Accident Sequence Precursor Analysis of Loss of Vital I&C Bus and Trip Event at McGuire Nuclear Station, Unit 1 Comment 1. Event Quantification The draft ASP report " Summary" section states that typical channel A vital 120 Vac loads would possiblyinclude a train of ESF slave relays. This is indeed the case for McGuire, since the train A slave relays are powered from 120 Vac vital power bus IEKVA. Thus automatic initiation of ESF train A loads was unavailable while bus IEKVA was unavailable. However, ESF train A loads could still have been actuated manually from the control room. This action is proceduralized and trained on, and is considered to be highly reliable.

The McGuire PRA model does not include loss of a 120 Vac vital power bus as an initiator, since this event is considered to be bounded by the loss of 125 Vdc power panelboard IEVDD. From the McGuire PRA, the loss of 125 Vdc power panelboard j IEVDD initiator is not risk-signiDeant, since there are no cut sets associated with this initiator in the Gnal core damage sequences. I The risk associated with the loss of 120 We vital power bus IEKVA can be estimated by considering reactor trip initiated sequences, cJong with any sequences in which loss of auto-initiation of a train of ESF loads could be expected to have an impact.

The reactor trip initiating event has a conditional core damage probability of 4.2E-7, or 0.6% of the nominal CDF of 7.4E-5. From Attachment 1, the dominant sequence (TQsU) involves an induced seal LOCA failure and failure ofinjection. Other sequences involve loss of secondary side cooling and either a failure to establish feed-and-bleed (TBP) or high pressure recirculation (TBX).

l These results were generated assuming that Main Feedwater is recovered at the historical i I

rate of 0.8. McGuire's Reportable Occurrence Report No. 82-52 refers to the i overpressurization of the condensate-feedwater system but states "through operator action l 1

these adverse effects were soon controlled and a stable hot standby condition was then i l

maintained." For example, a rupture on reheater IDI relief line piping could be mitigated  !

by closing ICM190 and ICM223, the reheater inlet and outlet motor-operated valves.

The available information on this event does not suggest that any other system (AFW, ECCS, etc.) was unavailable at the time of this event. However,if the analysis assumes that Main Feedwater is not recovered, then the reactor trip initiating event conditional core damage probability increases to 5.6E-7, or 0.8% of the nominal CDF.

A scenario involving a large-break LOCA is an example of a sequence which might be impacted by the loss of auto-initiation of a train of ESF loads, since the time available for manual action is relatively short. However, the likelihood of experiencing a large LOCA following a reactor trip is remote, since McGuire's large LOCA frequency is estimated at 3E-4/ reactor-yr.

In summary, this event is very similar to a routine reactor trip event and does not appear to meet the precursor threshold of IE-6.

It is recommended that the preliminary ORNL analysis be reviewed to take into account the comment provided herein.

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l 4

i

Sequence Percent Event .

Name Frecuency of CDF M Event Name Event Descriction TOsU 1.40E-6 0.2% 1.00E+1 T1 ReactorTrip initiating Event

  • 1.40E-5 WRNABPRCOM Common Cause Run Failure of Both RN Pumps 1.00E-0 WRNRVBKREC Operators Fail to Align RV Backup to RN TOsU 7.60E-7 0.1 % 1.00E+1 T1 Reactor Trip Initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 2.00E-0 JDG001ADGR Diesel Generator 1 A Fails to Run 2.00E-0 JDG001BDGR Diesel Generator 1B Fails to Run 1.90E-2 ACO2DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 2 Run TOsU 6.10E-7 0.0% 1.00E+1 T1 ReactorTrip Initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 4.36E-1 JDG001ATRM Diesel Generator 1 A in Maintenance or Testing 2.00E-0 JDG001BDGR Diesel Generator 1B Fails to Run 7.00E-2 AC01DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 1 Run TOsU 6.10E-7 0.0% 1.00E+1 T1 Reactor Trip initiating Event 1.00E-2 PACBOFTDEX Blackout Fo!!owing Trip 4.36E-1 JDG001BTRM Diesel Generator 1B in Maintenance or Testing 2.00E-0 JDG001ADGR Diesel Generator 1 A Fails to Run 7.00E-2 AC01DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 1 Run TOsU 3.92E-7 0.0% 1.00E+1 T1 Reactor Trip initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 2.80E-1 WRNTRNBTRM RN Train 1B Unavailable Due to Maintenance or Testing 1.40E-2 WRN001AWPS RN Pump 1 A Fails to Start TBP 1.80E-7 0.0% 1.00E+1 T1 ReactorTrip initiating Event 9.00E-0 -TNCOSRVDEX Pressurizer SRV Fails to Reseat After Relieving Liquid 2.00E-0 TCF0001 REC Failure to Restore Main Feedwater After Plant Trip 1.00E-1 FCACLMSCOM Common Cause Failure of CA Assured Sources 1.00E-2 FCAHOTWDHE Failure to Throttle During CA Suction From the Hotwell 1.00E-1 TFBLD01DHE Operators Fail To Establish Feed-and-Bleed Cooling TBX 1.80E-7 0.0% 1.00E+1 T1 Reactor Trip Initiating Event 9.00E-0 -TNCOSRVDEX Pressurizer SRV Fails to Reseat After Relieving Liquid 2.00E-0 TCF0001 REC Failure to Restore Main Feedwater After Plant Trip 1.00E-1 FCACLMSCOM Common Cause Failure of CA Assured Sources 1.00E-2 FCAHOTWDHE Failure to Throttle During CA Suction From the Hotwell 1.00E-1 TRECIRCDHE Operators Fail to Establish High Pressure Recirculation

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Sequence Percent Event ,

Name Frecuency gf C_D_E Prob. Event Name Event Description TOsU 1.74E-8 0.0% 1.00E+1 T1 Reactor Trip initiating Event 1.40E-S WRNABPRCOM Common Cause Run Failure of Both RN Pumps 1.24E-1 NNVRCPSLHE Latent Human Error Fails Reactor Coolant Pump injection  ;

1.00E-0 WRNRVBKREC Operators Fail to Align RV Backup to RN '

TOsU 7.60E-9 0.0% 1.00E+1 T1 Reactor Trip Initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 2.00E-0 JDG001ADGR Diesel Generator 1 A Fails to Run 2.00E-0 JDG001BDGR Diesel Generator 1B Fails to Run '

1.00E-1 ZWLM221DHE Failure to Correct M221 Valves Being Left Open 1.90E-2 . ACO2DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 2 Run TOsU 6.10E-9 0.0% 1.00E+1 T1 Reactor Trip Initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 4.36E-1 JDG001BTRM Diesel Generator 1B in Maintenance or Testing 2.00E-0 JDG001ADGR Diesel Generator 1 A Fails to Run '

1.00E-1 ZWLM221DHE Failure to Correct M221 Valves Being Left Open 7.00E-2 AC01DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 1 Run i TOsU 6.10E-9 0.0% 1.00E+1 T1 Reactor Trip initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip t 4.36E-1 JDG001ATRM Diesel Generator 1 A in Maintenance or Testing 2.00E-0 JDG001BDGR Diesel Generator 1B Fails to Run 1.00E-1 ZWLM221DHE Failure to Correct M221 Valves Being Left Open i 7.00E-2 AC01DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 1 Run TOsU 3.92E-9 0.0% 1.00E+1 T1 Reactor Trip initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 2.80E-1 WRNTRNBTRM RN Train 1B Unavailable Due to Maintenance or Testing 1.40E-2 WRN001AWPS RN Pump 1A Fails to Start 1.00E-1 ZWLM221DHE Failure to Correct M221 Valves Being Left Open

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Sequ nca Pzrcent Event Name Frecuency of CDF Prob. Event Name Event Description ,

TOsU 1.74E-10 0.0% 1.00E+1 T1 Reactor Trip initiating Event ,

1.40E-5 WRNABPRCOM Corrmon Cause Run Failure of Both RN Pumps 1.24E-1 NNVRCPSLHE Latent Human Error Fails Reactor Coolant Pump Injection * '

1.00E-0 WRNRVBKREC Operators Fail to Align RV Backup to RN '

1.00E-1 ' ZWLM221DHE Failure to Correct M221 Valves Being Left Open 2_=-- ,

==

Total: 4.17E-6 0.6% of Total CDF of 7.41 E-05 Secuence Percent of Total TOsU 91 %

TBP 4%

TBX 4%  ;

Attachment-2 0

Sequence Percent Event .

Name Frecuency f QCDF Prob. Event Name Event Description TOsU 1.40E-6 0.2% 1.00E+1 T1 . Reactor Trip initiating Event 1.40E-5 WRNABPRCOM Common Cause Run Failure of Both RN Pumps 1.00E-0 WRNRVBKREC Operators Fail to Align RV Backup to RN TBP 9.00E-7 0.1 % 1.00E+1 T1 ReactorTrip initiating Event 9.00E-0 -TNCOSRVDEX Pressurizer SRV Fails to Reseat After Relieving Liquid 1.00E+1 TCF0001 REC Failure to Restore Main Feedwater After Plant Trip 1.00E-1 FCACLMSCOM Common Cause Failure of CA Assured Sources

~ 1.00E-2 FCAHOTWDHE Failure to Throttle During CA Suction From the Hotwell 1.00E-1 TFBLD01DHE Operators Fail To Establish Feed-and-Bleed Cooling

{ TBX 9.00E-7 0.1 % 1.00E+1 T1 Reactor Trip initiating Event 9.00E-0 -TNCOSRVDEX Pressurizer SRV Fails to Reseat After Relieving Liquid 1.00E+1 TCF0001 REC Failure to Restore Main Feedwater After Plant Trip 1.00E-1 FCACLMSCOM Common Cause Failure of CA Assured Sources 1.00E-2 FCAHOTWDHE Failure to Throttle During CA Suction From the Hotwell 1.00E-1 TRECIRCDHE Operators Fail to Establish High Pressure Recirculation TOsU 7.60E-7 0.1% 1.00E+1 T1 ReactorTrip initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 2.00E-0 JDG001ADGR Diesel Generator 1A Fails to Run 2.00E-0 JDG001BDGR Diesel Generator 1B Fails to Run 1.90E-2 ACO2DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 2 Run TOsU 6.10E-7 0.0% 1.00E+1 T1 . ReactorTrip initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 4.36E-1 JDG001ATRM Diesel Generator 1 A in Maintenance or Testing 2.00E-0 JDG001BDGR Diesel Generator 1B Fails to Run 7.00E-2 AC01DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 1 Run TOsU 6.10E-7 0.0% 1.00E+1 T1 ReactorTrip initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 4.36E-1 JDG001BTRM Diesel Generator 1B in Maintenance or Testing 2.00E-0 'JDG001ADGR Diesel Generator 1A Fails to Run 7.00E-2 AC01DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 1 Run f

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Sequence Percent Event Name Freauency of CDF Prob. Event Name Event Description TOsU 3.92E-7 0.0% 1.00E+1 T1 Reactor Trip initiating Event .

1.00E-2 PACBOFTDEX Blackout Fo!!owing Trip 2.80E-1 WRNTRNBTRM RN Train 1B Unavailable Due to Maintenance or Testing 1.40E-2 WRN001AWPS RN Pump 1 A Fails to Start TOsU 1.74E-8 0.0% 1.00E+1 T1 ReactorTrip Initiating Event ,

1.40E-5 WRNABPRCOM Common Cause Run Failure of Both RN Pumps 1.24E-1 NNVRCPSLHE Latent Human Error Fails Reactor Coolant Pump Injection 1.00E-0 WRNRVBKREC Operators Fail to Align RV Backup to RN TOsU 7.60E-9 0.0% 1.00E+1 T1 Reactor TripInitiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 2.00E-0 JDG001ADGR Diesel Generator 1 A Fails to Run 2.00E-0 JDG001BDGR Diesel Gerierator 1B Fails to Run 1.00E-1 ZWLM221DHE Failure to Correct M221 Valves Being Left Open 1.90E-2 ACO2DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 2 Run TOsU 3.92E-9 0.0% 1.00E+1 T1 Reactor Trip Initiating Event 1.00E-2 PACBOFTDEX Blackout Fo!!owing Trip 2.80E-1 WRNTRNBTRM RN Train 1B Unavailable Due to Maintenance or Testing 1.40E-2 WRN001AWPS RN Pump 1 A Fails to Start 1.00E-1 ZWLM221DHE Failure to Correct M221 Valves Being Left Open TOsU 6.10E-9 0.0% 1.00E+1 T1 Reactor Trip initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 4.36E-1 JDG001BTRM Diesel Generator 1B in Maintenance or Testing 2.00E-6 JDG001ADGR Diesel Generator 1 A Fails to Run 1.00E-1 ZWLM221DHE Failure to Correct M221 Valves Being Left Open 7.00E-2 AC01DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 1 Run TOsU 6.10E-9 0.G% 1.00E+1 T1 ReactorTrip Initiating Event 1.00E-2 PACBOFTDEX Blackout Following Trip 4.36E-1 JDG001ATRM Diesel Generator 1 A in Maintenance or Testing  ;

2.00E-0 JDG001BDGR Diesel Generator 1B Fails to Run 1.00E-1 ZWLM221DHE Failure to Correct M221 Valves Being Left Open 7.00E-2 AC01DGRREC Off-site Power Not Restored Prior to Seal LOCA CM - 1 Run

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Sequence Percent Event

  • Name Freauency of CDF Prob. Event Name Event Descriotion

' ~

TOsU 1.74E-10 0.0% 1.00E+1 T1 1.40E-5 WRNABPRCOM Reactor Trip initiating Event Common Cause Run Failure of Both RN Pumps i*

1.24E-1 NNVRCPSLHE- Latent Human Error Fails Reactor Coolant Pump Injection -

1.00E-0 WRNRVBKREC Operators Fail to Align RV Backup to RN 1.00E-1 ZWLM221DHE Failure to Correct M221 Valves Being Left Open

==

Total: 5.61 E-6 0.8% of Total CDF of 7.41 E-05 Secuence Percent of Total TOsU 68 %

TBP 16%

TBX 16 %

-.._%

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