05000270/LER-1983-006, Forwards LER 83-006/03L-0.Detailed Event Analysis Encl

Forwards LER 83-006/03L-0.Detailed Event Analysis Encl

ML20079P949
Person / Time
Site:	Oconee
Issue date:	04/29/1983
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20079P951	List: 05000270/LER-1983-006, Forwards LER 83-006/03L-0.Detailed Event Analysis Encl
References
NUDOCS 8305110323
Download: ML20079P949 (3)

LER-2083-006, Forwards LER 83-006/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2702083006R00 - NRC Website

text

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Dunn Pownn Goduwxy 18.0. ISOX 331 TID CilAltl OTTIO. N.C. 215242 II AL 11. TUCKER TE I.E PH ON E WM E PSFhtDFRT (704) OMB-4 Nlt

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Mr. James P. O'Reilly, Regional Administrator N t.' ...

U. S. Nuc1 car Regulatory Commission co 7 '3 Region II  :, O 101 Marietta Street, NW, Suite 2900 g ]

o Atlanta, Georgia 30303 ?J z .

Re: Oconee Nuclear Station C

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Docket No. 50-270

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-270/83-06. This report is submitted pursuant to Oconee Nuclear Station Technical Specification 6.6.2.1.b(2) which concerns operation in a degraded mode permitted by a limiting condition for operation, 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.

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

, .; rnpy 8305110323 030429 PDR ADOCK 05000270 S

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o Duke Power Company Oconee Nuclear Station Report Number: R0-270/83-06 Report Date: April 29, 1983 Occurrence Date: April 1, 1983 Facility: Oconee Unit 2, Seneca, South Carolina Identification of Occurrence: Valve 2 LWD-1 was observed to be cycling open and shut, and was declared inoperable.

Conditions Prior to occurrence: 100% FP Description of Occurrence: On April 1, 1983, from the valve position indication, it appeared that containment isolation valve 2 LWD-1 (Liquid Waste Disposal) was cycling open and shut without operator action. Valve 2 LWD-1 was declared inoperable, thus placing the unit in a degraded mode per Technical Specification (T.S.) 3.6.

The affected penetration was isolated within four hours by the use of a deactivated automatic valve (2 LWD-2) which was secured and locked in the isolated position.

This assured operation of the unit in compliance with T.S. 3.6.3.b.(2) which states that a containment isolation valve may be inoperable provided those particular actions are taken.

Moments after the Reactor Building normal sump pump was automatically secured, valves 2 LWD-1 and 2 LWD-2 were closed from the Control Room. They had been opened in order to pump down the RB normal sump level. About two hours later, it was observed on the alarm typer that 2 LWD-1 had been cycling open and shut since it was first closed. The air supply to pneumatic valve 2 LWD-2 was isolated so that 2 LWD-2 could not be opened, l Apparent Cause of Occurrence: The cause of this occurrence is attributed to l component failure, even though the reason for the cyclic behavior of the valve cannot yet conclusively be explained. When valve 2 LWD-1 was first inspected, the yoke nut and locking sleeve were found on the floor while the valve motor was still running. There are two possible explanations of why the valve appeared to be cycling.

1) With the yoke nut off there was nothing holding the stem down, so as the water level changed in the sump, it would cause the valve to open to relieve pressure on the valve, or

2) With the motor running, the worn shaft would continue to turn, which would cause the limit switch to continuously open and shut.

After replacing the yoke nut and locking sleeve, and manually operating the valve, personnel were unsuccessful in setting the limit switch. While watching the valve stem, it was observed that it was rotating instead of functioning normally up and down. It was decided that the valve would need to be disassembled to find the root cause, and to make additional repairs to restore operability to the valve.

Analysis of Occurrence: During the time that valve 2 LWD-1 was inoperative and cycling open and shut, 2 LWD-2 was shut. Further, when people realized that 2 LWD-1 was cycling open and shut, action was taken to ensure that 2 LWD-2 would not and could not be opened, thus complying with T.S. 3.6.3.b.(2).

In addition, the section of pipe between the Reactor Building and 2 LWD-2 discharge, which includes 2 LWD-1, is seismic, so in the event of an earthquake or severe transient, the line should not break. The likelihood of an earthquake or severe transient in conjunction with a Loss of Coolant Accident (LOCA) is very small.

The health and safety of the general public were not endangered by this incident.

Corrective Actions: The immediate corrective action was to verify valve 2 LWD-2 as being shut and to take administrative control of 2 LWD-2 so it could not be operated. The valve operator for valve 2 LWD-1 was reassembled. The yoke nut and locking sleeve were installed and the threads above the locking sleeve were " staked"; damaging the threads in the drive sleeve; which should prevent the locking sleeve from unscrewing. The limit switch was adjusted and a terminal block was replaced. Those actions were still unsuccessful in making valve 2 LWD-1 operational. During an upcoming outage, 2 LWD-1 will be disassembled to determine why it presently will not operate.

An Operations precedure was revised so the Reactor Building Normal Sump could be drained without opening 2 LWD-2. A five year preventive maintenance (PM) program will be done on 2 LWD-1 during an upcoming outage. This PM consists of replacing the valve diaphragm.

I I