ML19209D190

LER 79-122/03L-0:on 791019,steam Generator C Support Temp Went Below Tech Spec Limit of 225 F.Caused by Operating Personnel Failing to Reconize Low Support Temp Until Lower Limit Was Exceeded.Heaters Energized to Increase Temp

ML19209D190
Person / Time
Site:	North Anna
Issue date:	10/18/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19209D187	List: ML19209D186 ML19209D190 ML19209D193
References
LER-79-122-03L, LER-79-122-3L, NUDOCS 7910190518
Download: ML19209D190 (2)

Text

NRC FORM 366 U. S. NUCLEAR REGULATORY COMMISSION (7-17)

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/ 8 W 61 DOCKET NUMBEN 68 09 EVENT O ATE REPOR T DAT E EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 lOn September 19, 1979, during nonnal power operation, the "C" steam generator support 1 o 3  ; temperature went below the Technical Specification limit of 225 F. The temperature o 4 lof the support was returned to greater than 225*F within the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> time 1imit I o s iallowed by the ACTION statement, therefore the health and safety of the general 1 0 6 lpublic were not affected by this event. Reportable pursuant to T.S. 6.9.1.9.b. l 0 7 ,  !

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, ,o j The support heaters were being operated in manual due to problems with Control l

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, , , system. Operating personnel failed to recognize the low support temperature until  !

the lower limit was exceeded. All support heaters were immediately energized to l increase the temperature above 225 F.

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Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 1 Docket No. 50-338 Report No. LER 79-122/03L-0 Description of Event On September 19, 19 79 , during steady state operation at 58% power, the "C" steam generator support temperature dropped below-the Technical Specifi-cation limit of 225'F. This event is contrary to T.S. 3.4.10.2.a.

Probable Consequences of Occurrence The consequences of this event were minimal because the temperature of the "C" steam generator support was restored to greater than 225'F within the time limit allowed by the ACTION statement. As a result, the public health and safety were not af fected by this event.

Cause ,

The support heaters were being operated in manual ene to problems with the RIJ's which provide feedback to the control system. Operating personnel failed to recognize the low support temperature until the low limit was exceeded. ,,

Immediate Corrective Action 4

All of the "C" steam generator support heaters were immediately energized to increase the temperature above 225'F.

Scheduled Corrective Action The defective P"D's will be replaced during the current refueling outage throu;M implementation of a' design change ifaterial m becomes available.

Otherwise =aintenance will repair the existing system. .

Actions Taken To Prevent Recurrence Operations personnel were instructed to monitor temperatures more closely and check for trends while taking logs.

4 1175 035

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