ML19289D725

LER 79-007/03L-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

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: ML19289D719 ML19289D725
References
LER-79-007-03L, LER-79-7-3L, NUDOCS 7903140286
Download: ML19289D725 (2)

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v 2, .g I While performinq surveillance procedure 01S-26. Main Steam L'ne leak Detectinn Tempera t tire,

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

]l which is in excess of the _< 200 F setpoint as specified in Table 3.2.1 of_the Technical i

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j l Specification. All other main steam line temperature switches were found to trip l m-jm L.._at values within Technical Specification limits.

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O geg.'RO l 719 l l-l l0l0l7 l/l l 01 3l lLl l-! l0l 21 22 23 24 26 27 28 29 30 31 32 ACT ION FUTURE EFFECT SHUTDOWN ATTACHYENT N P R O.4 PRIME COMP. Cc'.tPON EN T TAKEN ACTION CN PLANT METHOO HOURS SUGMITT ED FORMbUB. SUFPLIE R MAN U F ACTU't E R IE l@lZl@ l Zl@ l Z lh l 0 l0 l0 l0 l [y_j@ l Nlh lN lh l F l 0 l 8 l1 Ih 33 34 SS 3G 31 40 48 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS lil0 l l The cause of this occurrence was instrument setpoint drift. The t emne ra t u re switches I li li l l 16A, 18A, and 15C were re calibrated to trip at setpoints of 180 0F. 1800F. and 1810r I m ;j j respectively. l i a i  !

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Dave Hannum 309654-2241, ext. 252 NAME OF PREPARER PHONE: {

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l. 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.

Vll. CAUSE:

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

Vill. 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