ML19343C211
| 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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p 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 w