Part 21 Report - 1997-620

 
 

ACCESSION #: 9706190261



                                             GPU Nuclear, Inc.

G P U                                        One Upper Pond Road

     NUCLEAR                                 Parsippany, NJ 07054-1095

                                             Tel 201-316-7000



                              June 12, 1997

                              6730-97-2176



U. S. Nuclear Regulatory Commission

Attention: Document Control Desk

Washington, DC 20555



Gentlemen:



     Subject   10CFR Part 21 30-Day Report

               Oyster Creek Nuclear Generating Station

               Docket No. 50-219

               Potential Failure of General Electric Type CR120AD Relays



Oyster Creek has experienced failures of the General Electric Type

CR120AD relays.  The failure mechanism was identified as a manufacturing

defect; specifically, part of the start-end pigtail of the relay coils

was off the insulating lead pad and, therefore, lying directly on the

outer layer of the winding.  This configuration placed insulation on the

affected length of magnet wire in a high-electrical-stress condition that

led to dielectric breakdown at the failure site, thus effectively short

circuiting the coil.



Although our evaluation of all ten potentially defective relays installed

at Oyster Creek concluded that their fail-safe mode does not impact plant

safety, this potential defect is being conservatively reported in

accordance with 10 CFR Part 21.21, (d) (3) (ii).



Should you have questions regarding this matter, please contact Yosh

Nagai of our staff at (201) 316-7974.



                                   Sincerely,



                                   T. G. Broughton

                                   President



YN/plp



c:   Administrator, Region I

     NRC Resident Inspector

     Oyster Creek NRC Project Manager



                    10 CFR 21 - 30 DAY WRITTEN REPORT

                     CONCERNING POTENTIAL FAILURE OF

                  GENERAL ELECTRIC TYPE CR120AD RELAYS



1.   Name and Address Of The Individual Informing The Commission:



     Name:     T. G. Broughton

               President



     Address:  GPU Nuclear, Inc.

               One Upper Pond Road

               Parsippany, NJ 07054-1149



II.  Basic Component Affected:



     General Electric Type CR120AD Relays



III. Firm Supplying Components:,



     General Electric Nuclear Energy

     175 Curtner Avenue

     San Jose, California 95125



IV.  Nature of the Potential Defect:



     On March 26, 1996 Oyster Creek Generating Station issued a deviation

     report which identified an open coil in three CR120AD relays

     dedicated for safety-related use: one relay failed immediately after

     the installation when energized, another relay failed within two

     days during startup test and a third failed some months later during

     a surveillance test.  Following these incidents a coil from one of

     the failed relays was sent to General Electric (GE) for analysis and

     the two remaining relays were sent intact to an independent research

     laboratory (Southwest Research Institute) for failure analysis.



     After the analysis, Southwest Research Institute concluded that the

     principal problem observed in both relay coils was a manufacturing

     defect: specifically, part of the start-end pigtail of the coil was

     off the insulating lead pad and, therefore, lying directly on the

     outer layer of the winding, which was near the finish end of the

     coil.  This configuration placed insulation on the affected length

     of magnet wire in a high-electrical-stress condition that led to

     dielectric breakdown at the failure site, thus effectively short

     circuiting the coil.  Resulting high current through the short

     circuit caused the magnet wire to fuse and produced an energetic arc

     at the failure site.



     There are ten (10) potentially defective relays installed at Oyster

     Creek.  GPU Nuclear has concluded that their fail-safe mode does not

     Impact plant safety.  However, there may be other nuclear facilities

     with these relays installed or kept in their warehouse without

     knowing of or about this potential failure.



V.   Date on which Potential Defect Was Identified.



     We determined on May 9, 1997 that this potential failure of the GE

     relay CR120AD could have a generic implication and it was reported

     to NRC Operations Center, by phone, on May 9, 1997.



VI.  Number and Location of Components.



     There are ten (10) potentially defective relays installed at Oyster

     Creek.



VII. Corrective Actions Taken



     If a premature failure of any of these relays occurs, with an "open"

     coil as the failure mechanism, we may consider replacing the

     remaining nine relays.  However, replacement of the ten relays is

     not scheduled at this time for the following reasons:



     i)   The previous failures of the CR120AD relays at Oyster Creek

          occurred either immediately upon energization or within a few

          months of operation.  Also, none of the installed relays have

          failed since their installation approximately seven months ago.

     ii)  The probability of these relays having a potential

          manufacturing defect is extremely low.

     iii) Our evaluation concluded that there is no impact to plant

          safety due to their fail-safe mode feature.



                                             GPU Nuclear, Inc.

G P U                                        One Upper Pond Road

NUCLEAR                                      Parsippany, NJ 07054-1095

                                             Tel 201-316-7000



                                   June 12, 1997

                                   6730-97-2176



U. S. Nuclear Regulatory Commission

Attention: Document Control Desk

Washington, DC 20555



Gentlemen:



     Subject:  10 CFR Part 21 30-Day Report

               Oyster Creek Nuclear Generating Station

               Docket No. 50-219

               Potential Failure of General Electric Type CR120AD Relays



Oyster Creek has experienced failures of the General Electric Type

CR120AD relays.  The failure mechanism was identified as a manufacturing

defect; specifically, part of the start-end pigtail of the relay coils

was off the insulating lead pad and, therefore, lying directly on the

outer layer of the winding.  This configuration placed insulation on the

affected length of magnet wire in a high-electrical-stress condition that

led to dielectric breakdown at the failure site, thus effectively short

circuiting the coil.



Although our evaluation of all ten potentially defective relays installed

at Oyster Creek concluded that their fail-safe mode does not impact plant

safety, this potential defect is being conservatively reported in

accordance with 10 CFR Part 21.21, (d) (3) (ii).



Should you have questions regarding this matter, please contact Yosh

Nagai of our staff at (201) 316-7974.



                                   Sincerely,



                                   T. G. Broughton

                                   President

YN/plp



c:   Administrator, Region 1

     NRC Resident Inspector

     Oyster Creek NRC Project Manager



                    10 CFR 21 - 30 DAY WRITTEN REPORT

                     CONCERNING POTENTIAL FAILURE OF

                  GENERAL ELECTRIC TYPE CR120AD RELAYS



1.   Name and Address Of The Individual Informing The Commission:



     Name:     T. G. Broughton

               President



     Address:  GPU Nuclear, Inc.

               One Upper Pond Road

               Parsippany, NJ 07054-1149



II.  Basic Component Affected:



     General Electric Type CR120AD Relays



III. Firm Supplying Components:



     General Electric Nuclear Energy

     175 Curtner Avenue

     San Jose, California 95125



IV.  Nature of the Potential Defect:



     On March 26, 1996 Oyster Creek Generating Station issued a deviation

     report which identified an open coil in three CR120AD relays

     dedicated for safety-related use: one relay failed immediately after

     the installation when energized, another relay failed within two

     days during startup test and a third failed some months later during

     a surveillance test.  Following these incidents a coil from one of

     the failed relays was sent to General Electric (GE) for analysis and

     the two remaining relays were sent intact to an independent research

     laboratory (Southwest Research Institute) for failure analysis.



     After the analysis, Southwest Research Institute concluded that the

     principal problem observed in both relay coils was a manufacturing

     defect: specifically, part of the start-end pigtail of the coil was

     off the insulating lead pad and, therefore, lying directly on the

     outer layer of the winding, which was near the finish end of the

     coil.  This configuration placed insulation on the affected length

     of magnet wire in a high-electrical-stress condition that led to

     dielectric breakdown at the failure site, thus effectively short

     circuiting the coil.  Resulting high current through the short

     circuit caused the magnet wire to fuse and produced an energetic

     arc at the failure site.



     There are ten (10) potentially defective relays installed at Oyster

     Creek.  GPU Nuclear has concluded that their fail-safe mode does not

     impact plant safety.  However, there may be other nuclear facilities

     with these relays installed or kept in their warehouse without

     knowing of or about this potential failure.



V.   Date on which Potential Defect Was Identified.



     We determined on May 8, 1997 that this potential failure of the GE

     relay CR120AD could have a generic implication and it was reported

     to NRC Operations Center, by phone, on May 9, 1997.



VI.  Number and Location of Components.



     There are ten (10) potentially defective relays installed at Oyster

     Creek.



VII. Corrective Actions Taken



     If a premature failure of any of these relays occurs, with an "open"

     coil as the failure mechanism, we may consider replacing the

     remaining nine relays.  However, replacement of the ten relays is

     not scheduled at this time for the following reasons:



     i)   The previous failures of the CR120AD relays at Oyster Creek

          occurred either immediately upon energization or within a few

          months of operation.  Also, none of the installed relays have

          failed since their installation approximately seven months ago.

     ii)  The probability of these relays having a potential

          manufacturing defect is extremely low.

     iii) Our evaluation concluded that there is no impact to plant

          safety due to their fail-safe mode feature.



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