05000338/LER-1979-016-03, /03L-0 on 790213:main Steam trip,TV-MS-111A,valve Opened to Only 75% Capacity.Caused by Improperly Positioned Needle Valve Which Supplied Air to Valve Actuator.Valve Repositioned & Operation Restored

/03L-0 on 790213:main Steam trip,TV-MS-111A,valve Opened to Only 75% Capacity.Caused by Improperly Positioned Needle Valve Which Supplied Air to Valve Actuator.Valve Repositioned & Operation Restored

ML19273B548
Person / Time
Site:	North Anna
Issue date:	03/13/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19273B547	List: 05000338/LER-1979-016, Forwards LER 79-016/03L-0 05000338/LER-1979-016-03, /03L-0 on 790213:main Steam trip,TV-MS-111A,valve Opened to Only 75% Capacity.Caused by Improperly Positioned Needle Valve Which Supplied Air to Valve Actuator.Valve Repositioned & Operation Restored
References
LER-79-016-03L, LER-79-16-3L, NUDOCS 7904090157
Download: ML19273B548 (2)

LER-1979-016, /03L-0 on 790213:main Steam trip,TV-MS-111A,valve Opened to Only 75% Capacity.Caused by Improperly Positioned Needle Valve Which Supplied Air to Valve Actuator.Valve Repositioned & Operation Restored

Event date:
Report date:
3381979016R03 - NRC Website

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's Virginia Electric and Power Coacany North Anna Power Station, Unit fio. 1 Attachulent:

Page 1 of 1 Docket fio.

50-338 Report fio.

LER 79-016/03L-0

Description of Event

During normal po',;er opera tion, a t 90, it was discovered that the nain steam trip valve, TV-MS-111A would open only 75L.

This valve is located on the main steam line leading to the auxiliary stean driven 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 feeddater 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 />.

The other two motor driven feed pumps were operable and 1-FU-P-2 was returned to service within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

During repair of the trip valve, redundant valve 1-TV-MS-lllB remained operable, making the steam supply to the steam driven pump still available.

Therefore, the health and safety of the public were not endangered.

Cause

The needle valve in the air supply line to the valve actuator was impro-perly positioned.

The cause of the improper positioning of the valve is unknown.

Inmediate Corrective Action The needle valve was properly positioned.

The valve was found to work properly af ter the adjustment of the needle valve.

Scheduled Corrective Action No further action required.

Actions to Prevent P.ecurrence A means of preventing inadvertent movement of the needle valve is being investigated.