05000338/LER-1979-106-03, /03L-0:on 790904,during Normal Operation,Steam Generator C Support Temp Dropped Below Tech Specs.Cause Unknown.Temp Returned to Normal within 4-h Time Limit. Heaters & Control Circuits Checked,But No Faults Found

/03L-0:on 790904,during Normal Operation,Steam Generator C Support Temp Dropped Below Tech Specs.Cause Unknown.Temp Returned to Normal within 4-h Time Limit. Heaters & Control Circuits Checked,But No Faults Found

ML19209B229
Person / Time
Site:	North Anna
Issue date:	10/03/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19209B227	List: 05000338/LER-1979-106, Forwards LER 79-106/03L-0 05000338/LER-1979-106-03, /03L-0:on 790904,during Normal Operation,Steam Generator C Support Temp Dropped Below Tech Specs.Cause Unknown.Temp Returned to Normal within 4-h Time Limit. Heaters & Control Circuits Checked,But No Faults Found
References
LER-79-106-03L, LER-79-106-3L, NUDOCS 7910090356
Download: ML19209B229 (2)

LER-1979-106, /03L-0:on 790904,during Normal Operation,Steam Generator C Support Temp Dropped Below Tech Specs.Cause Unknown.Temp Returned to Normal within 4-h Time Limit. Heaters & Control Circuits Checked,But No Faults Found

Event date:
Report date:
3381979106R03 - NRC Website

text

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60 61 DOCKET NUMBER fid 63 EVENT DATE 74 74 HEPORT DATE SO EVENT DESCRIPTION AND PRODABLE CONSEQUENCES h f5"T21 10n September 4, 1979, durine normal power operation. the "C" steam eenerator 1

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Page 1 of 1 Docket ha. 50-338 Report No. LER 79-106/03tc0

Description of Event

on September 4,1979, during normal operation at 90% power, the temperature of the "C" steam generator support decreased below the Technical Specification limit of 225'F.

This event is contrary to T.S. 3.3.10.2.a and reportabic pursuant to T.S. 6.9.1.9.b.

Probabic Consequences of Occurrence The consequences of this event were minimal because the tempera ture of the steam generator support was returned to greater than 225'F vithin 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 resul t, the health and safety of the general public were not af fected by this occurrence.

At present, this event does not appear to be a generic proble.

Cause of Occurrence The cause for the decrease in support temperature is unknown at this time.

Immediate Corrective Action

Electrical maintenance personnel were called in to investigate and correct thc problem. Af ter approximately 30 minutes, the support temperature began to increase for no apparent reason and it eventually returned to acceptable limits.

The electricians found no fault with the heaters or heater control circuits.

Scheduled Corrective Action The steam generator support temperatures are presently being closely monitored to detect erratic behavior.

Actions Taken To Prevent Recurrence No further actions are required at this time.

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