05000293/LER-1980-038-01, /01T-0:on 800818,mode Switch in Shutdown Trip Function of Reactor Protection Sys Failed When B Vital Motor Generator Set Tripped.Caused by Relay 5A-K16B Being Energized & Relay 5A-K17B Being de-energized

/01T-0:on 800818,mode Switch in Shutdown Trip Function of Reactor Protection Sys Failed When B Vital Motor Generator Set Tripped.Caused by Relay 5A-K16B Being Energized & Relay 5A-K17B Being de-energized

ML19331D815
Person / Time
Site:	Pilgrim
Issue date:	08/29/1980
From:	Mathis C BOSTON EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19331D812	List: 05000293/LER-1980-038, Forwards LER 80-038/01T-0 05000293/LER-1980-038-01, /01T-0:on 800818,mode Switch in Shutdown Trip Function of Reactor Protection Sys Failed When B Vital Motor Generator Set Tripped.Caused by Relay 5A-K16B Being Energized & Relay 5A-K17B Being de-energized
References
LER-80-038-01T, LER-80-38-1T, NUDOCS 8009030607
Download: ML19331D815 (2)

LER-1980-038, /01T-0:on 800818,mode Switch in Shutdown Trip Function of Reactor Protection Sys Failed When B Vital Motor Generator Set Tripped.Caused by Relay 5A-K16B Being Energized & Relay 5A-K17B Being de-energized

Event date:
Report date:
2931980038R01 - NRC Website

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8 60 61 DOCK ET NUM8ER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES 01o 10121 l Contrary to Technical Specification, Table 3.1.1, the " Mode Switch in Shutdown" tri) l l function of the RPS failed when "B" vital MG set tripped.

Public health and safety l

o i3, lwere not affected since movement of the mode switch through startup to shutdown would l l 0 1.s l io l3i lhave scrammed the reactor on 15% APRM trip had a scram been necessary, g

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40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h 13 10 l ] Investigation showed that relay 5A-K16B was energized and relay 5A-K17B was de-energiz9d 11 I l The problem was resolved by mant ally picking up the SA-K17B which dropped out 5A-K16B l L1

,,,7, jand reset the logic. A design change is being processed to provide permanent correctipn iil3l l of the problem.

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% POWE R OTH ER STATUS CI RY DISCOVERY DESCRIPTION 11151 l E l@ l 0 l 9 l 8 l@l N.A.

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ACTIVITY CO TENT RELEASED OF RELEASE AMOUNT OF ACTIVITY LOCATION OF RELEASE l 1 l 6 l l Z l @ l Z l@l N.A.

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l PERSONNEL ExPOSSES NUMBER TYPE

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l PER$0NN E L INJURIES NUMBER

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8 9 11 12 80 LOSS OF OR DAMAGE TO FACILITY TYPE

DESCRIPTION

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7 8 9 10 Charles J. Mathis 617-746-7900 o

NAME OF PREPARER PHONE:

BOST0ff EDIS0!! C0:1pAI.T I'ILGRD! !."JCLEAR POWER STATIO!!

DOCKET No. 50-293 Attachment to LER 80-038/01T-0 On 8/18/80 at 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br /> the "B" vital MG set failed causing the associated reactor protection system bus to go dead. When the alternate power was applied, operations noted that the annunciator " shur.down scram reset permissive" came in and stayed in.

A request was made to investigate the problem with the alarm.

At 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br />, investigation showed that relay SA-K16B was energized, and relay SA-K17B was de-energized.

. With this configuratica, the mode switch channel "B3" manur,L scram by. going to the shutdown position was bypassed.

The scenario of this event follows:

1.

On loss of AC power 5A-K17B timed out in 2 seconds and closed contacts 1-2 and 3-4, 2.

When power was re-established to the "B" RPS bus, the 5A-K16B relay picked up immediately and opened contacts 1-2 preventing SA-K17B from resetting.

3.

With SA-K173 contacts 3-4 closed and SA-K16B contacts 3-4 closed, the shutdown position mode switch scram is precluded for channel "B3."

The immediate problem was resolved ar 1730 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.58265e-4 months <br /> by MR 80-3138 being generated to manually pick up 5A-K17B which dropped out 5A-K16B and reset the logic.

The final resolution, however, will require a design change.