05000338/LER-1980-107-03, /03L-0:on 801226,while Operating at 59% Power, Steam Generator 1B Steam Pressure Channel II Observed Indicating High,Resulting in Channel Being Locked In.Caused by Sensing Line for Pressure Transmitter 1484 Freezing

/03L-0:on 801226,while Operating at 59% Power, Steam Generator 1B Steam Pressure Channel II Observed Indicating High,Resulting in Channel Being Locked In.Caused by Sensing Line for Pressure Transmitter 1484 Freezing

ML20002D348
Person / Time
Site:	North Anna
Issue date:	01/14/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20002D344	List: 05000338/LER-1980-107, Forwards LER 80-107/03L-0 05000338/LER-1980-107-03, /03L-0:on 801226,while Operating at 59% Power, Steam Generator 1B Steam Pressure Channel II Observed Indicating High,Resulting in Channel Being Locked In.Caused by Sensing Line for Pressure Transmitter 1484 Freezing
References
LER-80-107-03L, LER-80-107-3L, NUDOCS 8101200437
Download: ML20002D348 (2)

LER-1980-107, /03L-0:on 801226,while Operating at 59% Power, Steam Generator 1B Steam Pressure Channel II Observed Indicating High,Resulting in Channel Being Locked In.Caused by Sensing Line for Pressure Transmitter 1484 Freezing

Event date:
Report date:
3381980107R03 - NRC Website

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U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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On December 26, 1980, while operating at 59% power steam generator IB steam

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pressure indicator was observed to be indicating high (1050 PSIG). Since the /

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affected channel was placed back in service within one hour, the health and

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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This event was caused by the sensing line for pressure transmitter 1484 freez- /

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from blowing in past the sensing line.

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NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 8101200 N

Virginia Electric and Power Company North Anna Power Station, Unit 1 Attachment: Page 1 of 1 i

Docket No. 50-338 Report No. LER 80-107/03L-0

Description of Event

On December 26, 1980, while operating at 59% power, steam generator 1B steam pressure channel II was observed to be indicating high (1050 PSIG) resulting in channel II of the steam line differential Safety Injection being locked in.

This occurrence is contrary to T.S. 3.3.2.1 and repor.~eable pursuant to T.S. 6.9.1.9.b.

Probable consequences of Occurrence Since the affected channel was back in service in lesa than one hour, and two redundant channels were available to initiate a safety injection if necessary, the health and safety of the public were not affected.

Cause of Event

The event was caused by cold air being drawn through the lower door of the Main Steam Valve House past the sensing lines for steam generator IB pressure transmitter 1484. This cold air caused the sensing lines to freeze up, thereby causing the pressure indication for PT-1484 to read high.

Immediate Corrective Action

i The immediate corrective action was to place a heat lamp on the sensing line and to block the air flow through the door.

Scheduled Corrective Action The scheduled corrective action is to install louvers on the Main Steam Valve House Lower Security door. A maintenance report has been issued for this work.

Actions Taken to Prevent Reccurrence No futher actions is required.

Generic Implications There are no generic implications to this event.