05000254/LER-1979-023-03, /03L-0 on 790717:high Pressure Switch in Safety Relief Valve Controller Found Inoperable During Reactor High Pressure Automatic Blowdown Functional test,QIS-40.Caused by Loosened Lead Wire from Switch to Terminal

/03L-0 on 790717:high Pressure Switch in Safety Relief Valve Controller Found Inoperable During Reactor High Pressure Automatic Blowdown Functional test,QIS-40.Caused by Loosened Lead Wire from Switch to Terminal

ML19242D210
Person / Time
Site:	Quad Cities
Issue date:	07/30/1979
From:	Dunesia Clark COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19242D201	List: 05000254/LER-1979-023, Forwards LER 79-023/03L-0 05000254/LER-1979-023-03, /03L-0 on 790717:high Pressure Switch in Safety Relief Valve Controller Found Inoperable During Reactor High Pressure Automatic Blowdown Functional test,QIS-40.Caused by Loosened Lead Wire from Switch to Terminal
References
LER-79-023-03L-02, LER-79-23-3L-2, NUDOCS 7908140690
Download: ML19242D210 (3)

LER-1979-023, /03L-0 on 790717:high Pressure Switch in Safety Relief Valve Controller Found Inoperable During Reactor High Pressure Automatic Blowdown Functional test,QIS-40.Caused by Loosened Lead Wire from Switch to Terminal

Event date:
Report date:
2541979023R03 - NRC Website

text

NRC FORM 366 U.S. NUCLEAR REGULATORY CoMMISSloN (7 77)

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tea 61 DOCKET NUMBER 63 69 EVENT DATE 74 75 PEPORT DATE 80 EVENT DESCRIPTION AND PROBA8LE CONSEQUENCES h F6 T il l W h i l e performing reactor high pressure automatic blowtown funct ional J

test, QlS 40, the hi 3n pressure switch in the Target Rock safety / relief o

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valve con t ro l l E. r wa s found inoperable (T.S.

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manual, and safety functions of the valve were still operable.

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o ]The lead wire from the switch to tha terminal had come loose.

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gleadwire had not been securely tighted to the terminal when the switch 3

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had been replaced and tested during the last surveillance.

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LER NUMBER 79-23/03L-0 11.

LICENSEE NAME COMMONWEALTH EDIS0N COMPANY QUAD-CITIES NUCLEAR POWER STATION lli.

FACILITY NAME UNIT ONE IV.

DOCKET NUMBER 050-254 V.

EVENT DESCRIPTION

On July 7, 1979, the instrument maintenance department pe r fo rme d the reactor high pres s ure a utoma t i c b lowdown func-tional test, QlS 40.

While performing the test, the mechanic fcund the high pre,sure switch in the Target Rock safety /

relief valve controller was inoperable.

This condition made the high p res s ure relief function of the 1-203-3A relief valve inoperable,ahich is contrary to Technical Specification 3 5.D.I.

The a u'.o -b l ow dow n, manual, and safety valve functions of the valve were still operable.

The fcur remaining relief valves were fun.tional tested satisfactorily.

An immediate investigation was begun to determine the problem.

The only problems previously encountered with the controller pr essure switches is setpoint drift; the most recent of wh;ch is documented in LER/R0 78-21/03L-0.

VI.

PROBABLE COLSEQUENCES OF THE OCCURRENCE One function of the Target Rock safety / relief valve is to protect the reactor vessel from overpressurization.

The valve utilizes a pressure sensing switch which operates an air-operated pilot valve.

The open pilot valve will cause the main disc to open and relieve the reactor pressure.

When the high pressure switch is inoperable, the relief pro-tection provided by this valve is lost.

However, since the safety mode was operable and is set at the same actuation pressure as the relief high pressure switch, overpressure protection was still in effect.

The automatic bic.down and manual modes of the valve were still operable and would have pe r fo rme d as designed unde r a ECCS initiation.

The four remaining electromatic relief valves and all nine reactor vessel safety valves were capable of keeping the reactor cool-ant boundary intact.

The high pressure coolant injection system was also operable throughout the duration of the occurrence.

Since the remainder of the system was operable and capable of controiling any abnormal transient; the primary coolant boundary integrity was not jeopardized as a result of this occurrence.

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CAUSE

The cause of this occurrence has been attributed to personnel pe r fo rmance.

The pressure switch had been replaced and tested during the last surveillance.

Since that time, the lead wire from the switch to the terminal came loose, rende ri ng the high pressure switch inoperable.

The lead wire had not been securely tightened to the terminal when the switch was replaced.

The pressure switch i s an intergral part of the Consoli-dated Electromatic Relief Valve Con t rol le r type 1539 VX.

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CORRECTIVE ACTION

The loose lead wire was found and reconnected to the proper te rmi na l.

The connector was tightened sufficiently to prevent the lead from coming loose again.

The high pressure switch was then retested satisfactorily.

A discussion was held with tha personnel involved in replacing the switch about the imr ance of cf.ecking over his work before finishing a job _nd performing work in a p ro f e s s i ona l manner.

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