ML19256A692

LER 78-128/03L-0 on 781214: After Main Steam Trip Valve 1-TV-MS-111A Was Opened During Reactor Trip It Failed to Close Fully.Caused by Washer Stuck in Mechanism

ML19256A692
Person / Time
Site:	North Anna
Issue date:	01/03/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19256A683	List: ML19256A682 ML19256A685 ML19256A692 ML19256A697 ML19256A701 ML19256A704
References
LER-78-128-03L, LER-78-128-3L, NUDOCS 7901090209
Download: ML19256A692 (2)

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14 7,a HE PO't T D AT E 80 b 00 61 DOCh ET NUYtll B E VENT DESCRIPTION AND PROB ABLE CONSEQUENCES n 7 After main steam trip valve 1-TV-MS- 1 A was opened during a reactor trip, it failed l g ,  ; to close fully and was isolated for repair. This valve is located on the main steam l g ,, ;1ine leading to the steam-driven steam generator auxiliary feedwater pump (1-FW-P-2). I

Isolation of the valve made the pump inoperable. Reportable pursuant to I g ;T.S. 6.9.1.9.b. J I

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44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i o lThe valve failed to close due to a washer stuck in the nechanism. The valve was 1

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Virginia Electric and Power Company North Anna Power Station, Unit No. 1

Attachment:

Page 1 of 1 Docket No. 50-338 Report No. LER 78-128/03-L Description of Event:

After main steam trip valve 1-TV-MS-lllA was opened during a reactor trip, it failed to close fully and was isolated for repair. At this time, it was discovered the valve would not cycle. This valve is located on the main steam line leading to the steam driven steam generator auxiliary feedwater pump (1-FW-P-2). A maintenance report was submitted on the valve to effect a repair which required isolating the valve and the steam supply to the pump.

Probable Consequences of Event-The steam line to the feedwater pump required isolation, thereby bringing into effect the action statement of T.S. 3.7.1.2. This calls for one of three auxiliary feedwater pumps to be powered by an operable steam supply within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of shutoff or to be in Hot Shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. However, parallel redundant valve 1-TV-MS-lllB leading to the pump remained operable.

The other two motor driven feed pumps were also operable. Therefore, the health and safety of the public was not endangered.

Cause:

The valve failed to close due to a washer stuck in the mechanism.

Immediate Corrective Action:

The valve was isolated and repaired.

Scheduled corrective Action:

No further action required.

Action Taken to Prevent Recurrence:

No further action required.