United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #: 9801280333



                                        Illinois Power Company

                                        Clinton Power Station

                                        P.O. Box 678

                                        Clinton, IL 61727

                                        Tel 217 935-5623

                                        Fax 217 935-4632



                                        Walter G. MacFarland IV

                                        Chief Nuclear Officer



ILLINOIS

  POWER                                 U-602910

                                        4F.140

An Illinova Company

                                        January 16, 1998



Docket No. 50-461                       10CFR21.21



Document Control Desk

Nuclear Regulatory Commission

Washington, D.C.  20555



Subject:  10CFR21 Interim Report 21-97-055: Westinghouse DHP

          Circuit Breaker Auxiliary Switch Operating Assembly Anomalies



Dear Madam or Sir:



     On November 20, 1997, Illinois Power (IP) identified an adverse

trend in auxiliary switch operating assembly anomalies in Westinghouse

DHP circuit breakers.  The anomalies were found in Clinton Power Station

(CPS) circuit breakers during maintenance activities performed at CPS and

at a circuit breaker refurbishment services supplier.  The auxiliary

switch operating assembly includes the auxiliary switches, the operating

link, and the operating cam (if applicable).  The anomalies found include

four cases of bent auxiliary switch links including two links exhibiting

cracks, and two cases of missing "E" clips (auxiliary switch link pin

retaining clip).  The bent auxiliary switch links appear to be caused by

the length of the link.  The E clips appear to have come off the link

pins as a result of excessive force occurring as the links bowed.  A

broken auxiliary switch link pin and two cases of lower auxiliary switch

cracking due to apparent binding were also found.  In all cases, the

weakest component in the auxiliary switch operating assembly appears to

have been the part that failed.  The supplier has seen one of the bent

and cracked links.  CPS has been discussing these anomalies with the

supplier to determine the cause for them and actions to prevent

recurrence.



     IP determined this issue was potentially reportable under the

provisions of 10CFR21 on November 20, 1997.



     Condition Report 1-97-11-388 was initiated to track investigation

and resolution of this adverse trend issue.  IP's evaluation of this

issue under the provisions of 10CFR21 has not been completed.  IP does

not have a firm date for resolving this issue but will provide, as a

minimum, an update on the resolution progress by March 24, 1998.



                                                  U-602910

                                                  Page 2



     Additional information about this issue may be obtained by

contacting D. G. Lukach, Plant Engineer, at (217) 935-8881, extension

3952.



                                        Sincerely yours,



                                        Walter G. MacFarland, IV

                                        Chief Nuclear Officer



RSF/krk



cc:  NRC Clinton Licensing Project Manager

     NRC Resident Office, V-690

     Regional Administrator, Region III, USNRC

     G. C. Wright, Region III, USNRC

     Illinois Department of Nuclear Safety

     INPO Records Center

     Westinghouse Nuclear Services Division



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