ML20023C702

Forwards Updated LER 83-012/01T-1.Detailed Event Analysis Encl

ML20023C702
Person / Time
Site:	Oconee
Issue date:	05/05/1983
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20023C703	List: ML20023C702 ML20023C711
References
NUDOCS 8305170561
Download: ML20023C702 (2)

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DUKE POWER COMPq7gp3g ,

P.O. box 3d180 CHARLOTTE, N.C. 28242 HALB.ECKER TELEPHONE

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May 5, 1983 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulator'y Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303

Subject:

Oconee Nuclear Station Docket Nos. 50-269, -270, -287

Dear Mr. O'Reilly:

Please find attached the Reportable Occurrence Report R0-269/83-12 supplement.

This report is submitted pursuant to Oconee Nuclear Station Technical Specifica-tion 6.6.2.1.a(2) which concerns an operation subject to a limiting condition for operation which was less conservative than the least conservative aspect of the limiting condition for operation established in the Technical Specifica-tions, and describes an incident which is considered to be of no significance with respect to its effect on the health and safety of the public.

Also attached is a corrected copy of R0-269/83-12 which replaces in its entirety the report sent April 22, 1983. It mistakenly reported the incident as occurring on March 8, 1983 instead of on the correct date of April 8, 1983.

Very truly yours, s.e Hal B. Tucker JCP/php Attachment cc: Document Control Desk Mr. J. J. Bryant U. S. Nuclear Regulatory Commission NRC Resident Inspector Washington, D. C. 20555 Oconee Nuclear Station INPO Records Center Mr. John Suermann Office of Nuclear Reactor Regulation Suite 1500 1100 Circle 75 Parkway U. S. Nuclear Regulatory Commission Atlanta, Georgia 30339 Washington, D. C. 20555 0305170561 830505 DR ADOCK 05000269 PDR

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Duke Power Company Oconee Nuclear Station Report Number: RO-269/83-12 Supplement Report Date: May 5, 1983 Occurrence Date: April 21, 1983 Facility: Oconee Units 1, 2, and 3, Seneca, South Carolina Identification of Occurrence: Loss of Prime on Condenser Circulating Water (CCW) Emergency Discharge Line - Supplement Conditions Prior to Occurrence: Oconee 1 100% FP Oconee 2 100% FP Oconee 3 100% FP Description of Occurrence: On April 21, 1983 at 0935 while performing Corrective Actions for Report R0-269/83-12, both Control Rooms received indication that the Emergency Discharge Valve to the Keowee Tailrace, CCW-8, was partially open, without having had any open command. This resulted in the loas of prime to all three units' emergency discharge and rendered the Emergency Condenser Discharge System inoperable per Technical Specification 3.4.5.

Apparent Cause of Occurrence: This incident was caused by component failure /

malfunction. Investigation discovered the DC ground to be in the cable that goes to valve CCW-9 (the valve that allows emergency discharge to the Intake Canal). CCW-9 is interlocked with CCW-8 such that when CCW-9 is called on to be open and is not fully open, then CCW-8 will remain open. Apparently, the insulation on the CCW-9 cable is slowly degrading, and while searching for the ground as part of the Corrective Actions for R0-269/83-12, the meter used for this search completed a circuit through the ground and the CCW-8 open coil.

This caused CCW-8 to open.

Analysis of Occurrence: During the period of time the Emergency CCW System was inoperable, the normal mode of condenser cooling was in service using the CCW pumps. In the event of loss of all station power or Keowee Dam failure, the atmosphere relief valves were available to remove heat to the atmosphere until the CCW Emergency Discharge System could be returned to service. The probability of a loss of all station power or dam failure during the 75 minutes in question is very low. Therefore, the health and safety of the public were not affected by this incident.

Corrective Action: The valve CCW-8 was electrically closed from the Control Room, and the system was subsequently reprimed, thus returning the system to operability.

The cable is to be replaced. Future modifications will be made to physically protect the cable leading to CCW-8 and CCW-9. A procedure has been written that will provide a method of designating the location of underground cables.