05000254/LER-1979-007-03, /03L-0 on 790201:main Steam Line Leak Detection Temp Switches TS 1-261-16A,MTS 1-261-18A & TS 1-261-15C Tripped in Excess of Setpoint.Caused by Instrument Setpoint Drift.Temp Switches Recalibrated

/03L-0 on 790201:main Steam Line Leak Detection Temp Switches TS 1-261-16A,MTS 1-261-18A & TS 1-261-15C Tripped in Excess of Setpoint.Caused by Instrument Setpoint Drift.Temp Switches Recalibrated

ML19289D725
Person / Time
Site:	Quad Cities
Issue date:	02/20/1979
From:	Hannum D COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19289D720	List: 05000254/LER-1979-007, Forwards LER 79-007/03L-0 05000254/LER-1979-007-03, /03L-0 on 790201:main Steam Line Leak Detection Temp Switches TS 1-261-16A,MTS 1-261-18A & TS 1-261-15C Tripped in Excess of Setpoint.Caused by Instrument Setpoint Drift.Temp Switches Recalibrated
References
LER-79-007-03L, LER-79-7-3L, NUDOCS 7903140286
Download: ML19289D725 (2)

LER-1979-007, /03L-0 on 790201:main Steam Line Leak Detection Temp Switches TS 1-261-16A,MTS 1-261-18A & TS 1-261-15C Tripped in Excess of Setpoint.Caused by Instrument Setpoint Drift.Temp Switches Recalibrated

Event date:
Report date:
2541979007R03 - NRC Website

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switches TS 1-261-16A, TS 1-261-18A, and TS 1-261-15c were found to trip _at 210 F l

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NAME OF PREPARER PHONE:

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LER NUMBER:

LER/R0 79-07/03L-0 11.

LICENSEE NAME: Commonwealth Edison Company Quad-Cities Nuclear Power Station Ill.

FACILITY NAME: Unit One IV.

DOCKET NUMBER: 050-254 V.

EVENT DESCRIPTION

On February 1, 1979, with Unit One in the REFUEL mode, routine surveillance QlS-26 was performed on the main steam line high temperature switches.

During the surveillance TS 1-261-16A, TS 1261-18A and TS 1-261-15C were found to trip in excess of <~~

200 F setpoint as specified in Table 3 2.1 of the Technical Specification. All other switches were found to trip within limits.

VI.

PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The purpose of these temperature switches is ao initiate a closure of the main steam isolation valves, steam drain valves, and primary sample valves in the event of a Group I isolation condition. Due to the fail safe logic of any one out of the four temperature switches de-energizing the primary relay in the logic circuit, a Group i isolation would have occurred at or below the 200 F setpoint as specified in Table 3.2.1. of the Technical Specifications.

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CAUSE

Instrument drift caused the setpoints to exceed the Technical Specification limitation.

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CORRECTIVE ACTION

The switches were recalibrated and tested satisfactorily. The "as found" and "recalibrated" setpoints are as follows:

EQUIPMENT PIECE NUMBER AS FOUND (OF)

RECALIBRATED ( F)

TS 1-261-16A 210 180 TS 1-261-18A 210 180 TS 1-261-15C 210 181