ML20043A869

LER 90-004-00:on 900418,ground Fault on Motor Control Ctr Feeder Breaker Occurred & Resulted in de-energization of Reactor B Protection Sys.Cause Not Determined.Feeder Breaker & Trip Device replaced.W/900516 Ltr

ML20043A869
Person / Time
Site:	Hope Creek
Issue date:	05/16/1990
From:	Cowles R, Hagan J Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-004-02, LER-90-4-2, NUDOCS 9005230216
Download: ML20043A869 (5)

Text

L O PSEG Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jon.ey 08038 Hope Creek Generating Station May 16, 1990 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear Sir:

HOPE CREEK GENERATING STATION DOCKET NO. 50-354 UNIT NO. 1 LICENCEE EVENT REPORT 90-004-00 This Licensee Event Report is being submitted pursuant to the requirements of 10CFR50.73(a) (2) (iv) .

Sincerely,

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.J. gan General Manager - ' I' Hope Creek Operat. dons RBC/

Attachment SORC Mtg.90-046 C Distribution 9005230216 900516 PDR ADOCK 05000354 /

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On 4/18/90 at 0740, control room personnel received indication of a channel "B" Reactor Protection System (RPS) half scram and various channel "B" and "D" huclear Steam Supply Shutoff System (NS4) isolations.

l Investigation determined that the motor generator set'(MG set) for the "B" channel RPS buo had tripped due to de-energization of its associated Motor control Center (MCC) when the MCC feeder breaker tripped on a spurious "

ground fault. Extensive troubleshooting by Maintenance Department and Systems Engineering could not pinpoint a definitive cause for the ground fault in the feeder breaker. As corrective actions, the feeder breaker and its associated solid state trip device were replaced. Additionally, Systems Engineering will continue to track similar failures under the station performance monitoring program and take further action if a trend' ,

of similar failures emerges.

LIGNSEE DIhT RDORT (IIR) 'lIXT OWTINUhTlm FACIII!Y NME: (1) D0%E'l N'MER (2) IIR NLMER (6) PNE (3)

YEAR ** NUPEER ** RtV ID'E: OHX GDURhTING LTATICN 0500054 90 -

0 0 4 -

0 0 0 2 0F 0 4 ELANT AND SYSTEM IDENTIFICATION ,

General Electric - Boiling Water Reactor (BWR/4) '

Reactor Protection System (EIIS Designation: JC) ,

Nuclear Steam Supply shutoff System (EIIS Designation: JM)

IDENTIFICATION OF OCCURRENCE 3

Ground Fault on Motor Control Center Feeder Breaker Results In.

De-energization of "B" Reactor Protection System Motor

• Generator Set and Various Containment Isolations j Event Date: 4/18/90 Event Time: 0740 This LER was initiated by Incident Report No.90-040 CONDITIONS PRIOR TO OCCURRENCE Plant in OPERATIONAL CONDITION 1 (Power Operation), Reactor Power 100%, Unit Load ll19MWe,

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DESCRIPTION OF OCCURRENCE At 0740 on 4/18/90, control room personnel received indication of a channel "B" Reactor Protection System (RPS) half scram and the following channel "B" and "D" Nuclear Steam Supply Shutoff .

System (NS4) containment isolations: '

BG-HV-F004, Reactor Water Cleanup Inboard Isolation-Valve  ;

BB-SV-4311, Reactor Recire System Sample Valve AB-IIV-F067A through D, Main Steam Isolation Valve (MSIV)

Sealing Steam Supply Valves >

AB-HV-F019, Outboard MSIV Drain Line Iholation Valve Investigation determined that the motor. generator (MG) set for 5 the "B" RPS bus had tripped due to~de-energization of its associated Motor Control Center (MCC) when the MCC feeder breaker tripped on a ground fault. The "B" RPS was.then placed [

on alternate power, the channel "B" RPS half scram was reset, and the above listed NS4 isolations were verified and reset. A four hour non-emergency report.was made to the NRC Operations Center IAW 10CFR50.72.

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IACILTIY NME (1) IOCllT MPEHi (2) in MPEER (6) PAGE (3)

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APPARENT CAUSE OF OCCURRENCE i

Indeterminate. Extensive troubleshooting of the MCC feeder breaker and associated.colid state trip (SST) device could not '

pinpoint a definitive cause for the ground fault trip of the breaker.

ANALYSIS OF OCCURRENCF4 5 i

Troubleshooting, including bench testing of the feeder breaker and ground fault isolation on the ' subject MCC, was conducted by Systems Engineering and the station Maintenance Department.  ;

-All associated control power circuits and the SST for the feeder breaker were checked, with no apparent problems noted.

The MCC and "B" RPS MG set were placed back in service with no  ;

further problems.-

MANUFACTURER INFORMATION Manufacturert General Electric ,

Breaker Type: 480VAC AKR PREVIOUS OCCURRENCES A review of past station incident ~ reports indicates no previous occurrences of spurious power source ground faults resulting in any plant transients. A review of the MCC and  ;

feeder breaker component history indicates no past history of  !

problems with either the MCC or the breaker.- 6 SAFETY SIGNIFICANCE This occurrence had no potential impact on plant safety or the i health and safety of the public. The RPS and NS4 systems functioned as designed,. and redundant channels were available in both systems to miticate the consequences of this incident i had the plant been in a more limiting condition at' the outset of the transient.  :

CORRECTI_VE ACTIONS

1. The feeder breaker and associated SST were replaced, s

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CORRECTIVE ACTIONS. CONT'D

2. Systems Engineering will continue to track similar failures under the station performance monitoring program and take further action if a trend of similar failures-emerges.

Sinc rely, ,

. gan General Manager - ,

llope Creek Operations RBC/

SORC Mtg.90-046 1

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