ML20154Q454

Final Significant Deficiency Repts 230-2 & 231-2 Re Failures of Aluminum Vertical Bus & Belleville Washers in Cutler-Hammer Motor Control Ctrs.Aluminum Vertical Bus Replaced W/Tin Plated Copper Bus

ML20154Q454
Person / Time
Site:	Limerick
Issue date:	09/28/1988
From:	Kowalski S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Russell W NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
SDR-230-2, SDR-231-2, NUDOCS 8810030403
Download: ML20154Q454 (2)

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PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET P.O. BOX 8699 PHILADELPHIA. PA.19101 (zis) e414502 S. J. KOWALSKI vICs PnselDsNT

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Mr. W. T. Russell, Administrator U.S. Nuclear Regulatory Ccnmisslor., Region 1 Attn: Doctment Control Desk Mall Station No. P1-137 Washington, DC 20555

Subject:

Significant Deficiency Report Nos. 230-2 and 231-2 Final Report for Failures of Aluninun Vertical Bus and Belleville Washers in Cutler-Hanmer MCCs Limerick Generating Station, Unit 2 NRC Construction Permit No. CPPR-107

References:

1. Letter frcm S. J. Kowalski to W. T. Russel (NRC) dated July 15,1988 (SDR tb. 230-2) ,

2. Letter frcm S. J. Kowalski to W. T. Russell (NRC) dated July 15, 1988 (SDR No. 231-2)

Flie: QUAL 2-10-2 (SDR Nos. 230-2 and 231-2)

Dear Sir:

This letter Is our final response as ccmr'tted to In our previous correspondence, References 1 and 2, that were forwarded In accordance i with 10CFR Part 50.55(e) requirements. These deficiencies were j determined to be reportable por 10CFR Part 50.55(e).

Our evaluation of the subject deficiencies has been completed and corrective action determined as follows:

! SDR tb. 230-2 The tronufacturer has recenmended replacement of altminun vertical l

bus with tin plated copper bus on MCC vertical sections feeding size 3 and 4 rnotor starters and/or feeder breakers rated 70 amp or greater. We are taking a trore conservative approach and are ,

replacing a11 of the altmlntm vertical bus with tin plated copper  !

bus.

The use of tin plated copper bus will preclude bus failures at the connection point between the carpartment stab block and the vertical bus because of copper's greater heat transfer capability.

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8810030403 880993 PDR ADOCK 0500u353 ffb 1 o i s PDC

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SUR No. 231-2 To resolve the deficiercy with the Belleville washers and to preclude its recurrence we are replacing the existing plated carbon steel washers, used at the vertical bus to horizontal bus connection point, with stainless steel Belleville washers. These new washers are functionally similar to the original design and are not as susceptible to hydrogen onbrittictrent because a plating process is not involved.

The rework associated with both deficiencies discussed above will be completed prior to Limerick Generating Station, Unit 2 startup.

In conclusion, we consider SDR tbs. 230-2 and 231-2 closed with the issuance of this report. If you have any further questions, please contact us.

Sincerely, DSM/sw/09208801 Copy to: W. Y. Russell, Administrator United States Nuclear Regulatory Conmission Region 1 631 Park Avenuo King of Prussia, PA 19406 R. A. Gramm, Senior Resident inspector Limerick Generating Station, Unit 2 U.S. Nuclear Regulaf.ory Conmission Sanatoga, PA 19464 l

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