ML19256E482

LER 79-122/03L-0:on 790919,during Normal Operation,Steam Generator C Support Temp Fell Below Tech Specs Limit of 225 F.Caused by Personnel Failure to Recognize Low Support Temp Until Temp Exceeded.Support Heaters Energized

ML19256E482
Person / Time
Site:	North Anna
Issue date:	10/18/1979
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19256E479	List: ML19256E482
References
LER-79-122-031, LER-79-122-31, NUDOCS 7911070500
Download: ML19256E482 (2)

Text

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68 59 74 IS REPOR T OATE 60 7 61 DOCKET Nuve ER EVENT OATE EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h o 2 i On September 19, 1979, during nomal power operation, the "C" steam generator suoport I o 3, i teniperature went below the Technical Saecification limit of 225'F. The temperature l o ,  ; of 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 limit I o s i allowed by ths ACTION statement, therefore the health and safety of the general l F6Tdl Ipublic were not affected by thi event. Reportable pursuant to T.S. 6.9.1.9.b.

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

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D 0 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 Descriotion 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 millmal because the temperature of the "C" steam generator support was restored to greater than 225'F vithin the ti=e limit allowed by the ACTION statement. As a result, the public health and safety were not affected by this event.

Cause' s

Se support beaters were being operated in manual due to problems with the PC'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 All of the "C" steam generator support heaters were immediately energized to increase the temperature above 225'F.

Scheduled Corrective Action The defective RTD's will be replaced during the current re..ueling outage through implementation of a design change if e terial becomes available. ,

Otherwise maintenance vill repair the existing system.

• Actions Taken To Prevent Recurrence /

Operations personnel were instructed to monitor temperatures more closely und check for trends while taking logs.

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