ML19343C211

RO 50-219-76-19-1T:on 760805,while Performing APRM Surveillance Test,Channel 7 Failed to Trip Per Simulated High Power Conditions & Channels 3,5,6 & 8 Bypassed for Several Minutes.Caused by Loose Pin Receptacle in Chassis

ML19343C211
Person / Time
Site:	Oyster Creek
Issue date:	08/06/1976
From:	Rone A JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
RO-50-219-76-19, NUDOCS 8103020123
Download: ML19343C211 (3)

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Initial Telephone Date of Report Date: Occurrence: August 5, 1976 Initial Written Time of I Report Date: Occurrence: 1356 OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Reportable Occurrence Report No. 50-219-76-19-1T IDENTIFICATION OF OCCURRENCE: Violation of the Technical Specifications, Table 3.1.1, Section A Item 8 Note C when two APRM's in the same quadrant were concurrently bypassed and two APRM's in

, the same trip system were concurrently. inoperable.

This event is considered to be a Reportable Occurrence as defined in the Technical Specifications, paragraph 6.9.2.a.2.

CONDITIONS FRIOR TO OCCURRENCE: XX Steady State Power Routine Shutdown Hot Standby Operation Cold Shutdown Load Changes During Routine Refueling Shutdown Power Operation Routine Startup Other (Specify)

Operation POWER: Reactor 1819 MWt i Generator 610 MWe FLOW: Recirc. 58.3x106 b/Hr.

Feedwater 6.77x10 Lb/Hr.

STACK GAS: 12,E00 uci/sec.

i DESCRIPTION l OF OCCURRENCE: On Thursday, August 5, 1976 at 1415 hours0.0164 days <br />0.393 hours <br />0.00234 weeks <br />5.384075e-4 months <br /> while performing l the weekly APRM surveillance test and calibration, it was l observed that APRM channel 7 failed to trip under simulated i High power conditions. Prior to discovery, APRM channel 3 l which monitors reactor power in the same qua'drant as APRM cnannel 7, was bypassed for approximately 3 minutes. In addition, APRM channels 5, 6 and 8 which are in the same trip system as APRM channel 7were individually bypassed for l

a total time of approximately 14 minutes. Table One lists l the out of service times for each APRM.

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TABLE ONE OUT OF SERVICE TIMES OUT OF IN CHANNEL SERVICE SERVICE 1 .

1340 1346 2 1351 1356 3 1356 1359 4 1346 1351 5 1400 1404 6 1410 1415 7 1415 1911 8 1405 1410 Following discovery APRM channel 7 was removed from service, repaired, surveilled and returned to standby service at 1911 of the same day.

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Reportable Occurrence f50-219-76-19-1T '-

Pag 2 Two '

APPARENT CAUSE OF OCCURRENCE: Design Procedure Manufacture Unusual Service Condition Installation /. Inc. Environmental Construction Component Failure Operator XX Other (Specify)

The cause of the occurrence was traced to a loose pin receptacle in the APRM chassis. The trip bias unit plugs into this receptacle and normally transmits the APRM power signal to the trip unit. This resulted in a condition whereby the high power rod block and scram functions associated with APRM channel 7 were rendered inoperable.

ANALYSIS OF OCCURRENCE: Had a high power condition occurred in the core quadrant monitored by APRM channel 7 during the time APRM channel 3 was concurrently bypassed, a rod block or scram would not have resulted. It should be noted that the requirement for operability of one APRM in each quadrant is predicated on a rod withdrawal error causing a local high power con-dition and a rod b ock being initiated to prevent further rod withdrawal. This condition existed for approximately 3 minutes during which no control rods were withdrawn. Had a condition occurred causing an increase in bulk core power during the time APRM's 5, 6 or 8 were bypassed for testing the remaining operable APRMs would have acted to terminate the transient.

CORRECTIVE ACTION: The faulty pin receptacle was repaired and the APRM was surveilled successfully and returned to service.

FAILURE DATA: N/A PREPARED BY .

IPt{ DATE: August 6, 1976

~ A. H. Rone

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