05000346/LER-1980-092-03, /03L-0:on 801219,isolation Valve from Main Steam Line to Auxiliary Feed Pump Turbine Failed to Close W/Simulated Low Pressure.Caused by Failed Couch Relay R1. New Relay Installed

/03L-0:on 801219,isolation Valve from Main Steam Line to Auxiliary Feed Pump Turbine Failed to Close W/Simulated Low Pressure.Caused by Failed Couch Relay R1. New Relay Installed

ML19341A244
Person / Time
Site:	Davis Besse
Issue date:	01/16/1981
From:	Frohne R TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19341A241	List: 05000346/LER-1980-092, Forwards LER 80-092/03L-0 05000346/LER-1980-092-03, /03L-0:on 801219,isolation Valve from Main Steam Line to Auxiliary Feed Pump Turbine Failed to Close W/Simulated Low Pressure.Caused by Failed Couch Relay R1. New Relay Installed
References
LER-80-092-03L, LER-80-92-3L, NUDOCS 8101220429
Download: ML19341A244 (2)

LER-1980-092, /03L-0:on 801219,isolation Valve from Main Steam Line to Auxiliary Feed Pump Turbine Failed to Close W/Simulated Low Pressure.Caused by Failed Couch Relay R1. New Relay Installed

Event date:
Report date:
3461980092R03 - NRC Website

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T NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (7 77) a LICENSEE EVENT REPORT

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o i i-8 60 61 DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 I (NP-33-80-116) On 12/19/80 during the performance of ST 5071.04, Auxiliary Feedwater l l System Functional Test, MS-106, the isolation valve from the main steam line to the l

o 3 l auxiliary feed pump turbine failed to close with a simulated low pressure. Aux Feed-l o 4 l water Train 1-1 was declared inoperable, and the station entered the action statement l o s l c i s 1 l of T.S. 3. 7.1. 2.

There was no danger to the health and safety of the public or sta-l [o TTl I tion personnel. MS-106 would have closed by the redundant instrumentation.

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33 34 35 Wa 31 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h M lThe cause was a failed Couch relay R1.

Ttis relav closes when it senses the actuatient l of pressure switches PSL106A and PSL106C. When low pressure was simuinted ne ebne:n I

i s l switches, the relay did not close. Under MWO 80-4105. a new relay was installed. At 1 i 7 3 3 l 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> on 12/19/80 MS-106 was retested per applicable steps of ST 5071.04, and thel y l Station was removed from the action statement.

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-ll6 r

DATE OF EVENT: December 19, 1980 FACILITY: Davis-Besse Unit 1 I

IDENTIFICATION OF OCCURRENCE: Failure of MS-106 to shut on a simulated low steam pressure Conditions Prior to Occurrence: The unit was in Mode 1,'with Power (MWT) = 1515 and Load (Gross MWE) = 492.

Description of Occurrence: On December 19, 1980, operations personnel were perform-ing ST 5071.04, Auxiliary Feedwater System Channel Functional Test. Portions of this test consist of simulating low steam pressure conditions and insuring that the appro-priate steam inlet valve (MS-106) shuts. At 1240 hours0.0144 days <br />0.344 hours <br />0.00205 weeks <br />4.7182e-4 months <br />, MS-106 failed to close on a low steam pressure condition, and the station entered Action Statement (a) of Techni-cal Specification 3.7.1.2.

This statemenc requires that the inoperable feedwater train be restored to service within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or the plant be placed in a hot shutdown status within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. MS-106 was then shut by means of the control room pushbutton HIS196A.

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Designation of Apparent Cause of Occurrence: The improper operation of MS-106 is apparently due to the intermittent failure of Couch relay, R1.

This relay will cause MS-106 to close when it senses the actuation of pressure switches PSL106A and PSL106C.

When a low pressure condition was simultated at both switches, R1 did not close.

In a like manner, MS-106 will also close when R3 senses the actuation of pressure switches PSL106B and PSL106D. When low pressure was simulated at these switches, R3 did close and cause MS-106 to close as designed. Therefore, the problem was isolated to Couch relay Rl.

The replacement of R1 with a new relay resulted in the proper operation of MS-106. The failure of R1 is attributed to the component failure in the relay.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. Auxiliary Feedwater Train 2 had been verified operable prior to testing Train 1.

Corre'ctive Action: Couch relay R1 was replaced under Maintenance Work Order' 80-4105.

MS-106 was twice retested satisfactorily per the applicable steps of ST 5071.04. At i

1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> on December 19,1980, MS-106 was declared operable, and the station was removed from the action statement of Technical Specification 3.7.1.2.

Facility Change Request 79-361 has been written to evaluate the use of Couch relays in the Auxiliary j

Feedwater System.

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- Failure Data: Previous Couch relay problems were repcrted in Licensee Event Renorts NP-33-80-62 (80-051), NP-33-79-126 (79-109), NP-33-79-121 (79-104), NP-33-79-94 (79-077),

and NP-33-79-39 (79-036).

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LER #80-092 I