ML20083N264
| ML20083N264 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 05/16/1995 |
| From: | Di Rito P NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLS950124, NUDOCS 9505230001 | |
| Download: ML20083N264 (3) | |
Text
4 COOPER NUC'_ EAR STATION P.o. box 98, BRoWNVILLE. NEBRASKA 64321 x
Nebraska Public Power District "tMMW" G.
r NLS950124 May 16, 1995 U.
S.
Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C.
20555
Subject:
Special Report Pursuant to Technical Specification 3.15.C.2 Cooper Nuclear Station, NRC Docket 50-298, DPR-46 Gentlemen:
On May 15, 1995, a loss of switchyard 12.5 KV power resulted in temporary inoperability of the Fire Suppression Water (FSW) System. Cooper Nuclear Station (CNS) Technical Specification 3.15.C.2 requires the submittal of a Special Report within one working day whenever the FSW System is inoperable.
The report is to discuss the cause of the inoperability, action taken, and plans and schedule for restoring the system to operable status.
Cause of the Inoperability Flow for the CNS FSW System is provided by one electric-driven pump (FP-P-E) and one diesel-driven pump (FP-P-D).
An additional electric pump (FP-P-C) is available as an installed backup. The Fire Water Pumps auto-start on low fire water header pressure. An "ectric jockey pump maintains the header pressurized to prevent inadvertent pump starts.
On May 15, 1995, at 1510 a phase-to-phase short circuit on a 12.5 KV power line occurred due to a failed shield wire.
Initially, the extent of the fault in the 12.5 KV System was not known and Abnormal Procedure 2.4.6.14, " Loss of 12.5 KV Power" was entered. This procedure required the primary electric fire water pump and the diesel-driven fire water pump to be rendered inoperable by placing their control switches in the pull-to-lock position (thereby defeating the auto-start feature).
This procedural step is required to prevent pump damage due to erroneous pump starts resulting from system pressure decay (the jockey pump loses power in this transient).
This configuration left FP-P-D and FP-P-E availab.e for manual initiation.
The backup electric pump (which was unaffected by tne transient) was available for providing alternate FSW System capability.
Action Taken Shortly after the Abnormal Procedure was entered, investigations determined that the plant experienced only a partial loss of 12.5 KV System power which did not, in fact, impact the Fire Water Pumps.
Accordingly, the pumps were restored to their normal switch configurations and returned to operability at 1522 that day.
The NRC was informed of this event by telephone within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of occurrence, as specified in the CNS Technical Specifications.
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' Plans and Schedule for Restoring System to Operability As discussed in the previous paragraph, the Fire Suppression Water System has been restored to operability. Owing to the short period of system inoperability, the availability of the primary electric and diesel-driven fire pumps for manual actuation, and the availability of the backup electric fire pump, the safety significance of this event was low.
Sincerely, P.
J.
Di Rito Operations Manager
/nr cc:
L.
J.
Callan G.
R.
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H.
Mueller.
R.
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Jones i
R. A.
Sessoms K.
C. Walden INPO Records NRC Resident Inspector R.
J.
Singer CNS Training CNS Quality Assurance b
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LIST OF NRC COMMITMENTS l ATTACHMENT 3 l
Correspondence No: NLS950124 The following table identifies those actions committed to by the District in this document.
Any other actions discussed in the submittal represent intended or planned actions by the District. They are described to the NRC for the NRC's information and are not regulatory commitments.
Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.
COMMITTED DATE COMMITMENT OR OUTAGE N/A NONE l
PROCEDURE NUMBER 0.42 l
REVISION NUMBER 0 l
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