05000338/LER-1979-117-03, /03L-0:on 790913,excessive Steam Observed Leaking Past Seat of Trip Valve TV-MS111A.Caused by Valve Not Fully Seating.Seating Surfaces Were Cleaned & Gaskets Replaced

/03L-0:on 790913,excessive Steam Observed Leaking Past Seat of Trip Valve TV-MS111A.Caused by Valve Not Fully Seating.Seating Surfaces Were Cleaned & Gaskets Replaced

ML19209C619
Person / Time
Site:	North Anna
Issue date:	10/12/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19209C617	List: 05000338/LER-1979-115-03, /03L-0:on 790913,loop B Steam Indicator Read Lower than Redundant Indicator.Caused by Leaking of Transmitter Root Valves Resulting in Loss of Ref Leg Level.Steam Flow Channel Tripped & Loop Calibr 05000338/LER-1979-117-03, /03L-0:on 790913,excessive Steam Observed Leaking Past Seat of Trip Valve TV-MS111A.Caused by Valve Not Fully Seating.Seating Surfaces Were Cleaned & Gaskets Replaced 05000338/LER-1979-118-03, /03L-0:on 790914,temp of Steam Generator B Support Fell Below Tech Spec Limit.Caused by Personnel Error While Operating Support Heaters Manually.Heaters Energized to Increase Temp 05000338/LER-1979-119-03, /03L-0:on 790914,high Steam Line Differential Pressure Loop 2 Channel II Bistable Failed to Trip During Surveillance Test.Caused by Loose Lead on Signal Comparator Card.Card Replaced & New One Calibr ML19209C616
References
LER-79-117-03L, LER-79-117-3L, NUDOCS 7910160493
Download: ML19209C619 (2)

LER-1979-117, /03L-0:on 790913,excessive Steam Observed Leaking Past Seat of Trip Valve TV-MS111A.Caused by Valve Not Fully Seating.Seating Surfaces Were Cleaned & Gaskets Replaced

Event date:
Report date:
3381979117R03 - NRC Website

text

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Virginia Electric and Power Company

?! orth Anna Power Station, Unit #1 Attachments:

Page 1 of 1 Docket flo. 50-338 Report No. LER 79-ll7/03L-0

Description of Event

On September 13, 1979, steam was observed leaking past the seat of trip valve TV-MSillA.

During Mode 1 operation at 35% power, TV-MS111A was isolated for repair. This valve is located on the steam line leading to the steam driven steam generator auxiliary feedwater pump 1-FW-P-2.

Probable Consequences of Occurrence The steam supply line to the auxiliary 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 /> or 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 />.

Since the redundant valve TV-MSillB remained operable to supply steam to 1-FW-P-2 and both motor driven auxiliary feed pumps were available for operation, the health and safety of the general public were not affected by this event.

Potential generic implications exist because of past probicms encountered with these valves.

Cause of Occurrence The steam leak was caused by the valve not seating properly.

Immediate Corrective Action

After the valve was isolated, it was disassembled and the seating surfaces were inspected and cleaned. The trip valve was then reassembled with a new gasket set.

Scheduled Corrective Action No scheduled corrective action is required.

Actions Taken to Prevent Recurrence Causes of failure are being evaluated. The vendor has been contacted and his recommendations will be evaluated and implemented, as appropriate, during the refueling outage.

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