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

/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

ML19209C620
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-79-118-03L, LER-79-118-3L, NUDOCS 7910160496
Download: ML19209C620 (2)

LER-1979-118, /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

Event date:
Report date:
3381979118R03 - NRC Website

text

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On September 14, 1979, during Mode 1 operation, the temperature of the "B" steam I

Since Lgenerator support was less than the Technical Specification limit of 225 F.

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[the temperature of the support was restored to greater than 225 F within the time I

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Attachment:

Page 1 of 1 North Anna Power Station, Unit #1 Docket No. 50-338 Report No. LER 79-Il8/03L-0

Description of Event

On September 14, 1979, during steady state operation at 34% power, the temperature of the "B" steam generator support decreased below the Technical Specification limit of 225'F.

Probable Consequences of Occurretice The consequences of this event were minimal because the steam generator support temperature was returned to greater than 255"F within the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> time limit allowed by the ACTION statement. As a resalt, the public health and safety were not affected by this event.

Cause

The support heaters were being operated in manual due to probicas with the RTD's which provide feedback to the control system.

Operating perconnel failed to recognize the low support temperature until the low limit was exceeded.

Immediate Corrective Action

All the steam generator support heaters were immediately energized to increase the temperature above 225*F.

Scheduled Corrective Action A design change will be implemented during the current refueling outage to replace the defective RTD's if material becomes available.

Otherwise, naintenance will repair the existing system.

Actions Taken to Prevent Recit rrence Operations personnel were reminded to check for trends while taking logs, i

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