ML20199B620

Part 21 Interim Rept 21-97-055,identified Adverse Trend in Auxiliary Switch Operating Assembly Anomalies in W Dhp Circuit Breakers on 971120.Condition Rept 1-97-11-388 Initiated to Track Investigation & Resolution

ML20199B620
Person / Time
Site:	Clinton
Issue date:	01/16/1998
From:	Walter MacFarland ILLINOIS POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-98 U-602910, NUDOCS 9801280333
Download: ML20199B620 (2)

Text

Ilknois Power Company Ch ton t Staten Chnton. IL 61727 Tel 217 935-5623.

, Fax 217 935-4632 Walter G. MacFarland IV Chet Nuclear officer P4p M R u.6o29io

- An imnove company 4F.140 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 Operatina 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 breakea.1 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 oflower 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

/

g the supplier to determine the cause for them and actions to prevent recurrence.

s 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.

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Additional information about this (Asue may be obtained by contacting D. G.

Lukach, Plant Engineer, at (217) 935-8881, ntw, ion 3952.

Sincerely yours, N" &

Walter G. MacFarland, W ChiefNuclear Officer RSF/krk cc: NRC Clinton Licensing Project Manager NRC Resident Office, V.690 Regional Administrator, Region Ill, USNRC G. C. Wright, Region III, USNRC lilinois Deprtment of Nuclear Safety INPO Records Center Westir; house Nuclear Services Division k

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