05000254/LER-1981-012-03, /03L-0:on 810624,pressure Switch 1-5600-PS-3 Tripped Below Tech Spec Level During Loss of Electrohydraulic Fluid Pressure Calibr & Functional Test. Caused by Instrument Drift.Switch Recalibr & Tested

/03L-0:on 810624,pressure Switch 1-5600-PS-3 Tripped Below Tech Spec Level During Loss of Electrohydraulic Fluid Pressure Calibr & Functional Test. Caused by Instrument Drift.Switch Recalibr & Tested

ML20009E614
Person / Time
Site:	Quad Cities
Issue date:	07/10/1981
From:	Guest J COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20009E587	List: 05000254/LER-1981-012, Forwards LER 81-012/03L-0 05000254/LER-1981-012-03, /03L-0:on 810624,pressure Switch 1-5600-PS-3 Tripped Below Tech Spec Level During Loss of Electrohydraulic Fluid Pressure Calibr & Functional Test. Caused by Instrument Drift.Switch Recalibr & Tested
References
LER-81-012-03L-03, LER-81-12-3L-3, NUDOCS 8107280316
Download: ML20009E614 (2)

LER-1981-012, /03L-0:on 810624,pressure Switch 1-5600-PS-3 Tripped Below Tech Spec Level During Loss of Electrohydraulic Fluid Pressure Calibr & Functional Test. Caused by Instrument Drift.Switch Recalibr & Tested

Event date:
Report date:
2541981012R03 - NRC Website

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8 EVENT DESCRIPTION AND PROBA9LE CONSEQUENCES h o 2 l On June 24, 1981 wnile performing Q1S-39, Loss of Electrohydraulic Fluid Pressure l

Calibration and Functional Test, pressure switch 1-5600-PS-3 tripped at 887 psig.

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The Technical Specification Table 3 1-3 limit is greater than or equal to 900 psig.

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42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 27 lil0 j l The cause of this occurrence was instrument drift. The switch was recalibrated and functionally tested to verify the setpoint. The 1-5600-PS-3 has drifted l

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LER NUMBER:

LER/R0 81-12/03L-0 ll.

LICENSEE NAME:

Commonwealth Edison Company Quad-Cities Nuclear Power Station lit.

FACILITY NAME:

Unit One IV.

DOCKET NUMBER: 050-254 V.

EVENT DESCRIPTION

On June 24, 1981, at 2000 while performing routine surveillance test QlS-39, Loss of Electrohydraulic Fluid Pressure Calibration and Functional. Test, pressure switch 1-5600-PS-3 tripped at 887 Psig, which is 13 psi below the Technical Specification limit of greater than or equal to 900 psig. The three other pressure switches on the Unit were found to trip above 900 psig. The pressure switch was immediately recalibrated and tested satisfactorily.

VI.

PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The four pressure switches are arranged in a one out of two twice logic design. The three other switches were all within the Technical Specification limits. Therefore, an EHC low fluid pressure condition would have been detected above the Technical Specification limit, and a reactor scram would have been initiated. The safety of the plant was not af fected by this occurrence.

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CAUSE

The cause of the occurrence was instrument setpoint drif t.

The pressure switch is a mode: C9612-2, manufactured by Barksdale Company.

Vill. CORRECTIVE ACTION:

The immediate corrective action was to recalibrate the pressure switch to trip above the required setpoint. A functional test was then successfully performed. This switch had previously drif ted below the required setpoint during April 1980, but had perforred acceptably subsequent to that event until this failure.

No definite adverse trend has been exh:bited, hence no further corrective action is planned at this time.