ML20236E799

Final Part 21 Rept Re W Dhp Circuit Breaker Auxillary Switch Operating Assembly Anomalies.Caused by Loss of Breaker Safety Function.Dhp Circuit Will Be Inspected

ML20236E799
Person / Time
Site:	Clinton
Issue date:	05/26/1998
From:	Walter MacFarland ILLINOIS POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-98 NUDOCS 9806010284
Download: ML20236E799 (5)

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e.ia May 26, 1998 Docket No. 50-461 10CFR21.21 Document Control Desk Nuclear Regulatory Commission Washington, D. C. 20555

Subject:

10CFR21 Final Report 21-97-055: Westinghouse Dh[P Circuit Breaker Auxiliary Switch Operating Assembly Anomalies

Dear Madam or Sir:

On January 16,1998, Illinois Power (IP) issued 10CFR21 Interim Report 21 055 in letter U-602910 to notify the NRC that an evaluation under the provisions of 10CFR, Part 21 was not complete for anomalies in safety-related Westinghouse DHP circuit breaker auxiliary switch operating assemblies. IP provided an update to the NRC on the continuing evaluation of this issue in IP letter U-602968, dated March 24,1998.

IP has now completed the eva!uation of this issue and concludes that it should be reported under the provisions of 10CFR21. The basis for this conclusion is that the anomatics could cause a failure of the auxiliary switch operating assembly during

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breaker operation, resulting in loss of the breaker safety function. //

On November 20,1997, IP identi6cd an adverse trend of auxiliary switch ,-

operating assembly anomalies in Westinghouse DHP circuit breakers. The anomalies q were found in Clinton Power Station (CPS) circuit breakers during maintenance - I activities performed at both CPS and a circuit breaker refurbishment services supplier.

The auxiliary switch operating assembly includes the auxiliary switches, the operating link, and the operating cam (if applicable). Anomalies found included 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 auxthary switch links appeared to be caused by the length of the link. The "E" clips appeared 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.

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9806010284 980526 PDR ADOCK 05000461 g PDR

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, Condition report 1-97-11-388 was initiated to track an investigation and resolution of this adverse trend issue. On November 20,1997, IP determined this issue was potentially reportable under the provisions of 10CFR21.

IP is providing the following infonnation in accordance with 10CFR21.2I(d)(4).

Initial notification of this matter will be provided by facsimile of this letter to the NRC Operations Center in accordance with 10CFR21.21(d)(3) within two days of the date the responsible officer signs this letter.

(i) Walter G. MacFarland, IV, Senior Vice President and ChiefNudear OfBeer ofIP, Clinton Power Station, Highway 54, 6 Miles East, Clinton, Illinois, 61727, is informing the Nuc! car Regulatory Commission of a condition reportable under the provisions of10CFR, Part 21.

(ii) The basic component involved in this condition is the auxiliary switch operating assembly, including the auxiliary switches, the operating link, and the operating cam (if applicable), for Westinghouse Model DHP 4160-volt and 6900-volt circuit breakers.

(iii) The auxiliary switch operating assembly, including the auxiliary switches, the operating link, and the operating cam (if applicable), were supplied to Clinton Power Station by Westinghouse, Pittsburgh, PA, as part of Model DHP circuit l breakers.

(iv) The deviations identi6cd include four cases of bent auxthary switch links including two links exhibiting cracks, and two cases of missing "E" clips (auxiliary switch link pin retaining clip). The anomalies appear to be caused by stacked manufacturing tolerances associated with the auxiliary switch operating assembly.

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.

IP has concluded that this issue should be reported under the provisions of 10CFR21. The basis for this conclusion is that the deviations 'could cause a failure of the auxiliary switch operating assembly during breaker operation and result in loss of the breaker safety function and loss of safety function of associated equipment loads.

The circuit breaker could fail to trip or could fail to close. The closing and/or tripping function can be adversely impacted depending on when the auxiliary switch operating assembly fails during the operating cycle and the position of the auxiliary switch during or after the failure.

(v) The auxiliary switch operating assembly condition was identified and determined to be potentially reportable under the provisions of 10CFR21 on November 20,1997.

Q u.4030c7 Page 3 IP. notified the NRC in letters dated January 16,1998, and March 24,1998, that the evaluation of the issue was not complete, and additional time was needed for completing the evaluation.

' (vi)

' CPS has 43 DHP breakers ins'alled in safety-related applications and 2 sp.tre safety-related DHP circuit breakers potentially affected by the numliary switch operating assembly deficiencies. Other facilities using DHP circuit breakers could be aff'ected by this deficiency.

(vii) DHP circuit breakers will be inspected and reworked / refurbished as necessary

, prior to startup from the current outage. These activities include inspecting and correcting any auxiliary switch operating assembly deficiencies identified.

Currently, IP personnel are performing the inspection and rework activities, and a vendor is performing the refurbishment activity. In addition, DHP circuit breakers are currently inspected and reworked on a 3-year periodicity and refurbished on a 6 year periodicity under the preventive maintenance program.

(viii) IP has no advice about this issue for other purchasers or licensees.

Additionalinformation about this issue may be obtained by contacting R. A.

Philipps, Plant Engineer, at (217) 935.d881, extension 3464.

Sincerely yours, O

fu & '

Walter.G. MacFarland, IV Senior Vice President and ChiefNuclear Officer RSF/ndh cc: NRC Clinton Licensing Project Manager NRC Resident Office, V.690 Regional Administrator, Region III, USNRC Illinois Department ofNuclear Safety INPO Records Center Westinghouse

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• POWER REACTOR EVENT NUMBER: 34294 l

FACILITY: CLINTO!? REGION: 3 NOTIFICATION DATE: 05/28/98

, UNIT: [1] [] [] STATE: IL NOTIFICATION TIME: 12:15 [ET]

RX TYPE: [1] GE-6 EVENT DATE: 05/28/98 EVENT TIME: 10:00[CDT]

l NRC NOTIFIED BY: R.S. FRANTZ LAST UPDATE DATE: 05/28/98 HQ OPS OFFICER: FANGIE JONES NOTIFICATIONS EMERGENCY CLASS: NOT APPLICABLE 10 CFR SECTION: JOHN MADERA RDO l CDEG 21.21(c) (3) (i) DEFECTS / NONCOMPLIANCE VERN HODGE NRR i

UNIT SCRAM CODE RX CRIT INIT PWR INIT RX MODE CURR PWR CURR RX MODE 1 N N 0 COLD SHUTDOWN 0 COLD SHUTDOWN l

EVENT TEXT 10 CFR PART 21 FINAL REPORT REGARDING WESTINGHOUSE DHP CIRCUIT BREAKER AUXILIARY SWITCH OPERATING ASSEMBLY ANOMALIES ON JANUARY 16, 1998, ILLINOIS POWER (IP) ISSUED 10CFR21 INTERIM REPORT 21-97-055 IN LETTER U-602910. THIS NOTIFIED THE NRC THAT AN EVALUATION UNDER THE PROVISIONS OF PART 21 OF 10CFR WAS NOT COMPLETE FOR ANOMALIES IN l SAFETY-RELATED WESTINGHOUSE DHP CIRCUIT BREAKER AUXILIARY SWITCH OPERATING ASSEMBLIES. IP PROVIDED AN UPDATE IN LETTER U-602968 ON MARCH 24, 1998 TO THE NRC. IP HAS COMPLETED THE EVALUATION OF THIS ISSUE AND CONCLUDES THAT IT SHOULD BE REPORTED UNDER THE PROVISIONS OF 10CFR21. THE BASIS FOR THIS CONCLUSION IS THAT THE ANOMALIES COULD CAUSE A FAILURE OF THE AUXILIARY SWITCH OPERATING ASSEMBLY DURING BREAKER OPERATION, RESULTING IN LOSS OF THE BREAKER SAFETY FUNCTION.

THE ANOMALIES INCLUDED FOUR CASES OF BENT AUXILIARY SWITCH LINK AND TWO CASES OF MISSING "E" CLIPS. THE BASIC COMPONENT INVOLVED IN THIS CONDITION ,

IS THE AUXILIARY SWITCH OPERATING ASSEMBLY, INCLUDING THE AUXILIARY SWITCHES, THE OPERATING LINK, AND THE OPERATING CAM (IF APPLICABLE), FOR WESTINGHOUSE MODEL DHP 4160-VOLT AND 6900-VOLT CIRCUIT BREAKERS. THE ASSEMBLY WAS SUPPLIED BY WESTINGHOUSE, PITTSBURGH, PA, AS PART OF MODEL DHP CIRCUIT BREAKERS. l CLINTON POWER STATION HAS 43 DHP BREAKERS INSTALLED IN SAFETY-RELATED APPLICATIONS AND 2 SPARE SAFETY-RELATED DHP BREAKERS POTENTIALLY AFFECTED BY THE AUXILIARY SWITCH OPERATING ASSEMBLY DEFICIENCIES. DHP CIRCUIT I

BREAKERS WILL BE INSPECTED AND REWORKED / REFURBISHED AS NECESSARY PRIOR TO STARTUP FROM THE CURRENT OUTAGE.

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