ML20150C624

/03L-0 on 780914:an Inadvertent SI Occurred When 1A Diesel Generator Was Started Due to Bent Plunger Spring Causing Failure of Engine Trip Lockout Solenoid Valve (Asco 8320).Valves Replaced & Springs Checked

ML20150C624
Person / Time
Site:	Zion File:ZionSolutions icon.png
Issue date:	10/13/1978
From:	Ainger K COMMONWEALTH EDISON CO.
To:
Shared Package
ML20150C622	List: ML20150C620 ML20150C624
References
LER-78-092-03L, LER-78-92-3L, NUDOCS 7811240129
Download: ML20150C624 (2)

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? MJ 01 DOCKET NtRauEn 68 69 EVENT DATE 74 7b 8tPO3T DAT L W1 EVENT DESCRIPTION AND PROBABl.E CONSEQUENCES h 10121 1 Following a reactor trip f rom 61% power, the 1A diesel generator was j lo la l l started for turbine protection. The diesel came up to speed & then triPt L(LI.iJ l ped. 12 minutes later an inadvertent SI occurred. At the onset of the I lo lbi l SI, the 1A diesel came up to speed & trippe d. It tried to start 5 times l Fo lc i l be fore the SI was reset, but was not success ful. This was the firs t l 10171 Loccurrence of this type. The health & safety of the public were not l i o is l l af fected because 1B &O diesels came up to speed & voltage as required by l 7 eo the SI.n SYST E M CAUSE CAUSE COMP. VALVE CODE CODE SUDCODE COMPONENT CODE SUBCODE SUBCODE lo191 7 8 l E lE j@ lE l@ l B l@ lE l Nl G lI lN l El@ l Zl@ l Zl@

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l i l o I l Cause was failure of engine trip lockout solenoid valve (ASCO 8320) to I li li I l, block out low lube oil pressure trip present during SI start. Failure of 1i 121 I solenoid valve due to bent-plunger spring. Rag found in oil strainer j I i l a I [_ caused low oil pressure . Rag was removed from strainer. Valve was re- l

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a ATTACIIMENT TO LER No. _13 92_ / D1_ _L__

O COMMONNEALTl! EDISON CO. I 1

ZION GENERATING STATION 50-295 l

Description of Event Following a reactor trip from 61% power, the 1A diesel generator was started manually for turbine coastdown protection. The diesel came up to speed and then tripped. Twelve minutes later an inadvertent safety injection occurred. At the onset of the SI, the 1A diesel cane up to speed and tripped. It tried to start' 5 times be fore the SI was reset, but was not successful. This was the first occurrence of this type.

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Consequences of Occurrence, The health and safety of the public were not affected because 1B and 0 diesels came up to speed and voltage as required by the SI . Of fsite AC power was also available at the time.

Cause of Occurrence The cause of the event was a failure of the engine trip lockout solenoid valve to block out the low lube oil pressure trip that was present during the SI start. The solenoid valve could not perform its lockout function because a bent spring prevented the plunger from fully retracting into the plunger sleeve. With the plunger only partially retracted, the valve could not seat completely and block out the trip. The low lube oil pres-sure trip was present because the engine oil pressure never got above the trip setpoint. A rag that was trapped in the lube oil strainer prevented ge ecbe# M#cns i from reaching setpoint of the trip.

The rag was removed from the oil strainer and the failed solenoid valve was replaced. In addition, the lockout solenoid valves on other diesels were inspected and found to be satis factory. No further corrective action is warranted at this time.