PNO-II-86-069, on 861002,Units 1 & 2 Shut Down Due to Loss of Low Pressure Svc Water Pump Suction After Surveillance Test. Caused by Air Leakage in Pump Flange Seals.Leakage Areas Wrapped.All Units Shutdown Until Exact Cause Determined

PNO-II-86-069:on 861002,Units 1 & 2 Shut Down Due to Loss of Low Pressure Svc Water Pump Suction After Surveillance Test. Caused by Air Leakage in Pump Flange Seals.Leakage Areas Wrapped.All Units Shutdown Until Exact Cause Determined

ML20214G114
Person / Time
Site:	Oconee, 05002698
Issue date:	10/03/1986
From:	Brownlee V, Reyes L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
References
PNO-II-86-069, PNO-II-86-69, NUDOCS 8611250578
Download: ML20214G114 (2)

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October 3, 1986 PRELIMINARY NOTIFICATION OF. EVENT OR UNUSUAL OCCURRENCE PN0-II-86-47 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verifi-cation or evaluation, and is basically all that is known by the Region II staff on this date.

FACILITY: Duke Power Company Licensee Emergency Classification:

Oconee, Units 1, 2 & 3 Notification of Unusual Event Docket Nos. 50-269/270/287 Alert Seneca, South Carolina Site Area Emergency General Emergtncy X Not Applicable F

SUBJECT:

SHUTDOWN TO VERIFY OPERABILITY OF LOW PRESSURE SERVICE WATER SYSTEM DURING POSTULATED EMERGENCY OPERATING CONDITIONS The licensee began shutting down Oconee Units 1 and 3 at 9:00 a.m. (EDT) on October 2 after.a surveillance test of load shed circuits conducted during the afternoon and evening of October revealed that low pressure service water (LPSW) pump suction was lost after about two hours' operation.

The test was conducted on Unit 2 while down for refueling. Units 1 and 3 were each at 100 percent power.

Technical specifications require that the units be in hot shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> of LPSW pump inoperability and in cold shutdown within an additional 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

At 10:00 a.m. (EDT) on October 3, the company reported that overnight tests indicated that the problem appears to be associated with the fact that circulating cooling water pump flanges with metal-to-metal seals experienced inward air leakage thereby breaking the syphon effect necessary to maintain gravity flow through the circulating cooling water (CCW) system when off-site and backup power supplies are lost.

During overnight tests, the licensee wrapped suspected leakage areas with polyethylene sheets, reducing inward air flow and supporting continous gravity flow.

Oconee's three units are supplied with off-site power via six 240-KV and three 500-KV lines. The units have no emergency diesels and rely upon backup power supplies from nearby Lake Keowee Hydro Plant via overhead (seismically qualified) electric power lines, backed up by redundant underground power lines of lesser capacity. Should the overhead power sources be lost, the plant's ultimate heat sink would utilize gravity flow from the lake at a higher elevation, down through the plant's condenser and into the river below. Gravity flow is maintained through a syphon effect which is lost when outside air leaks into the system.

The licensee plans to restart Unit 2, which has been down for refueling, by October 10.

Unit I will remain down for maintenance for about 13 days and Unit 3 for approximately 23 days. The company has agreed that no units will restart until, the exact cause of the problem has been identified and NRC concurrence with its resolution has been obtained.

Prior to restart, the licensee will meet with Region II management. The resident inspectors, with regional support, are closely monitoring licensee activities.

The licensee issued a news release on the afternoon of October 2, and local media interest has occurred.

B611250578 861003 I jI PDR ILE L PNO-II-86-OO9 PDR

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x The State of South Carolina has been notified.

The NRC received initial notification of this event via telephone from the licensee to the headquarters duty officer on October at 3:28 p.m. (EDT).

This information is current as of 10:00 a.m. (EDT) on October 3.

Contact:

V. Brownlee 242-5583 L. Reyes 242-5623 DISTRIBUTION:

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Licensee:

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