Part 21 Report - 1998-170

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 *** END OF DOCUMENT ***

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