ML19282B837

LER 79-008/03L-0 on 790202:temp Switch TS-1-1360-15D Had Trip Setpoint in Excess of Tech Spec Limit.Caused by Setpoint Drift.Switch Recalibrated & Satisfactorily Tested

ML19282B837
Person / Time
Site:	Quad Cities
Issue date:	02/24/1979
From:	Reed M COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19282B831	List: ML19282B830 ML19282B837
References
LER-79-008-03L-02, LER-79-8-3L-2, NUDOCS 7903160246
Download: ML19282B837 (2)

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• w sc: Act: ;ct:c A7. cts 't c p i;, I tlhile performing procedure QlS 26-1 RCIC Turbine Area High Temperature Calibration) ,

-q{ temperature switch TS-1-1360-150 was found to have a trip setpoint of 204 F. This is j in excess of the Technical Specification Table 3.2-1 limit of less than or equal to  ;

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200 F. The remaining 15 RCIC temperature switches were found to trip below the limit.  ;

9 Because each sct of temperature switches is wired in a one-out-of-two-twice logic ,

scheme, the "D" set containing TS-1-1360-15D would have tripped at 180 F. ,

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g,g,gl setpoint drift. The switch was recalibrated and tested satisfactory by tripping l

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l. LER NUMBER: LER/R0 79-08/03L-0

11. LICENSEE NAME: Commonwealth Edison Company Quad-Cities Nuclear Power Station 111. FACILITY NAME: Unit One IV. DOCKET NUMBER: 050-254 V. EVENT DESCRIPTION:

On February 2, 1979 while performing procedure QlS 28-1 (RCIC Turbine Area High Temperature Calibration) temperature switch TS-1-1360-15D was found to have a trip setpoint of 204 F.

This is in excess of the Technical Specification limit of <

200 F. Unit One was in the Refuel Mode at the time of this occurrence. The remaining RCIC temperature switches were found to trip below the limit.

VI. PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The RCIC Area Temperature Monitoring System consists of sixteen temperature switches arranged in four sets of four. Each set is wired in a one-out-of-two-twice logic scheme. The "D" set of temperature switches, containing the TS-1-1360-15D switch, would have given a trip signal at 180 F, thus below the 200 F limit. Bes ides the redundan t "A", "B", and "C" channel s ,

additional protection was provided by the RCIC steam line high flow instrumentation.

Vll. CAUSE:

The TS-1-1360-15D swi tch exceeded the Technical Speci fication limit due to instrument setpoint drift. The temperature switch is model 17023-6 manufactured by Fenwall, Inc.

Vill. CORRECTIVE ACTION:

The TS-1-136015D switch was recalibrated and tested satisfactory.

The switch tripped at 188 F.