05000366/LER-1981-058-03, /03L-0:on 810622,during steady-state Operation at 2,194 Mw,Reactor Bldg to Torus Vacuum Breaker Isolation Valve 2T48-F310 Failed Open.Cause Attributed to Torus Differential Pressure Switch Setpoint Drift.Switch Recalibr

/03L-0:on 810622,during steady-state Operation at 2,194 Mw,Reactor Bldg to Torus Vacuum Breaker Isolation Valve 2T48-F310 Failed Open.Cause Attributed to Torus Differential Pressure Switch Setpoint Drift.Switch Recalibr

ML20009E922
Person / Time
Site:	Hatch
Issue date:	07/15/1981
From:	Nix R GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009E910	List: 05000366/LER-1981-058, Forwards LER 81-058/03L-0 05000366/LER-1981-058-03, /03L-0:on 810622,during steady-state Operation at 2,194 Mw,Reactor Bldg to Torus Vacuum Breaker Isolation Valve 2T48-F310 Failed Open.Cause Attributed to Torus Differential Pressure Switch Setpoint Drift.Switch Recalibr
References
LER-81-058-03L, LER-81-58-3L, NUDOCS 8107280546
Download: ML20009E922 (2)

LER-1981-058, /03L-0:on 810622,during steady-state Operation at 2,194 Mw,Reactor Bldg to Torus Vacuum Breaker Isolation Valve 2T48-F310 Failed Open.Cause Attributed to Torus Differential Pressure Switch Setpoint Drift.Switch Recalibr

Event date:
Report date:
3661981058R03 - NRC Website

text

NRC FOIM 366 U. Lk MELGA] RTGULATE.Y COMMIO31oM (7-77)

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8 60 61 DOCKET NUVBER 68 69 EVENT DATE 14 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h IO I2I I While the olant was in steadv state coeration at 7194 MWt. Reactnr Ruild-1 10i3 1 ing to Torus Vacuum Breaker Isolation Valve. 2T48-F310. failed open.

I IO I4 l l Tech Specs 3.6.3 reauires that Primary Containment Isolation Valves be l

lo isi l operable. Redundant Reactor Building to Torus Vacuum Breaker Isolation l

10isl l Valve, 2T48-F311 was operable.

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Differential Pressure Switch. 2T48-N210_ setonint drift.

The switch wac I

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A new switch has been ordered I

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LER No.: 50-366/1981-058 Licensee: Georgia Power Company Facility:

Edwin I. Hatch Docket No. :

50-366

Narrative

Report for LER 50-366/1981-058.

On June 22, 1981, while the plant was in steady state operation at 2194 MWt, Reactor Building to Torus Vacuum Breaker Isolation Valve, 2T48-F310, failed open. Tech Specs 3.6.3 requires that primary containment isolation valves be operable.

Redundant Reactor Building to Torus Vacuum Breaker Isolation Valve, 2T48-F311, was operable. Neither plant operation nor public health and safety were affected.

This is a repetitive event as reported on Reportable Occurrence Report No. 50-366/1981-051.

The cause of the event has been attributed to Reactor Building to Torus Differential Pressure Switch, 2T48-N210, setpoint drift. The switch was found to actuate at 5" water column and 'it should be 14" water column.

The switch was recalibrated as per HNP-2-5240, Static "0" Ring Pressure Switch Calibration, and functionally tested successfully.

The switch was returned to service. A new switch has been ordered and will be installed when received.

A generic review revealed no inherent problems with this type switch, i

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