05000483/LER-2002-010, Re Potential for Fire Induced Common Cause Failure
| ML022540242 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 08/30/2002 |
| From: | Witt W AmerenUE |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ULNRC-04720 LER 02-010-00 | |
| Download: ML022540242 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition |
| 4832002010R00 - NRC Website | |
text
Union Electric PO Box 620
- CallawayPlant Fulton, MlO 65251 August 30, 2002 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 AmerenULNRC-04720 Ladies and Gentlemen:
DOCKET NUMBER 50-483 Callaway PLANT UNIT 1 UNION ELECTRIC CO.
FACILITY OPERATING LICENSE NPF-30 LICENSEE EVENT REPORT 2002-010-00 Potential for fire induced common cause failure.
The enclosed licensee event report is submitted in accordance with 10CFR50.73(a)(2)(ii)(B) to report a licensee-identified potential for a common cause failure if a fire were to occur in Fire Area A-1.
Warren A. Witt Manager, Callaway Plant WAW/ewh Enclosure Cl?
a subsidiary of Ameren Corporation
ULNRC-04720 August 30, 2002 Page 2 cc:
Mr. Ellis W. Merschoff Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Jack N. Donohew (2 copies)
Licensing Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 7E1 Washington, DC 20555-2738 Manager, Electric Department Missouri Public Service Commission PO Box 360 Jefferson City, MO 65102 Mr. John O'Neill Shaw, Pittman, Potts & Trowbridge 2300 N. Street N.W.
Washington, DC 20037 Records Center Institute of Nuclear Power Operations 700 Galleria Parkway Atlanta, GA 30339 Mr. Scott Bauer Regulatory Affairs Palo Verde Nuclear Generating Station Arizona Public Service Company P.O. Box 52034-Mail Station 7636 Phoenix, AZ 85072-2034
_ULNRC-04720 August 30, 2002 Page 3 Mr. Dennis Buschbaum Comanche Peak SES Farm Road 56 P. 0. Box 1002 Glen Rose, TX 76043 Mr. Scott Head Supervisor, Licensing South Texas Project NOC Mail Code N5014 P.O. Box 289 Wadsworth, TX 77483 Mr. Pat Nugent Supervisor, Licensing PG&E Mail Stop 104/5/536 P.O. Box 56 Avila Beach, CA 93424
Abstract
On 6/25/02, with Callaway Plant in Mode I at 100 percent power, testing was being conducted involving "A" Train Ultimate Heat Sink (UHS) sump heater, SEF02A. When energized, the motor control center (MCC) feeder breaker, NG0705, tripped.
Investigation revealed that SEF02A was grounded and that its feeder breaker protection was not properly coordinated with the MCC feeder breaker. The next closest breaker with ground fault protection was NG0705.
An extent of condition review was completed that revealed a potential for safety related components and load centers to experience a common cause failure if a single fire were to occur in Auxiliary Building Fire Area A-1. MCC's NGO1 A and NG02A could experience a fire induced ground fault condition due to cable damage on downstream loads, which could cause the loss of either, or both, NGO1 A and NG02A.
In addition, cables in Fire Area A-1 for "A" and "B" Residual Heat Removal pump room coolers have less than the required 20 feet of horizontal separation per FSAR Table 9.5E-1.
Compensatory actions taken include establishment of hourly firewatches in affected areas, isolation of circuit breakers for UHS sump heaters pending completion of an electrical design change, issuing an Operations Night Order detailing actions to be taken to restore NGO IA andlor NG02A in the event of a fire, and evaluating revisions to Fire Area Pre-plans.
NRC FORM 366 (7-2001)
J1RC =
(If more space is required, use additional copies of SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES On 6/25/02, with Callaway Plant in Mode I at 100 percent power, a Non-Licensed Operator (NLO) was testing the "A" Train Ultimate Heat Sink (UHS) sump heater, SEF02A. When the NLO energized SEF02A, the motor control center (MCC) feeder breaker, NG0705, tripped. Investigation revealed that SEF02A was grounded and that its feeder breaker over current protection was not properly coordinated with the upstream MCC feeder breaker ground fault protection. The next closest breaker with ground fault protection was NG0705.
An extent of condition review was completed that revealed the potential for Safety Related components and electrical load centers to experience a common cause failure due to the miscoordination if a fire were to occur in the 1974' Auxiliary Building Fire Area A-I. Safety related MCC's NGOIA and NG02A (opposite trains) could experience a fire induced ground fault condition due to cable damage on downstream loads. This ground fault condition could cause the loss of either or both NGOIA and NG02A which supply post fire safe shutdown equipment like "A" and "B" Residual Heat Removal (RHR) pump room-coolers. It was concluded this scenario could impact post fire safe shutdown equipment.
In addition, it was identified that cables in Fire Area A-1 for the "A" and "B" Residual Heat Removal (RHR) pump room coolers, which are post fire safe shutdown equipment, have less than 20 feet of horizontal separation and do not meet the separation commitments documented in FSAR Table 9.5E-I.
The following compensatory actions have been taken:
. An hourly firewatch was established for the affected area on 7/2/02 as the evaluations were completed.
. Circuit Breakers associated with Essential Service Water Sump Heaters have been isolated, pending completion of a design change to address electrical coordination consistent with the FSAR.
- An Operations Night Order detailing actions to be taken to restore NGO1A and/or NGO2A if a fire were to occur that affected these load centers. Actions include measures to isolate faulted circuits.
. Revisions to Fire Area Pre-plans have incorporated the guidance of the Operations Night Order.
E. METHOD OF DISCOVERY OF EACH COMPONENT, SYSTEM FAILURE, OR PROCEDURAL ERROR The fire protection separation violation of FSAR Table 9.5E-1 commitments was discovered during an extent of condition review related to the ground fault failure of UHS sump heater SEF02A.
(If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
VI.
ADDITIONAL INFORMATION
The system and component codes listed below are from the IEEE Standard 805-1984 and IEEE Standard 803A-1984 respectively.
System:
ED Component: