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
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