ML20154E464

Part 21 & Deficiency Rept Re Belleville Washer Failures in Cutler-Hammer Motor Control Ctrs.Initially Reported During 880415 Telcon.Exam of Failed Washers Showed Failure Due to Intergranular Decohesion.Detailed Rept Expected by 880715

ML20154E464
Person / Time
Site:	Limerick
Issue date:	05/13/1988
From:	Kowalski S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
REF-PT21-88-080-000 PT21-88-080-000, PT21-88-80, NUDOCS 8805200225
Download: ML20154E464 (2)

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PHILADELPHIA ELECTRIC COMPANY-2301 MARKET STREET P.O. BOX 8699 PHILADELPHI A. PA.19101 (2:5) e414 sot S. J. KoWALSKI v lC E-P R E SI D E N T u u u . . . .. u . ...

May 13, 1988 United States Nuclear Regulatory Con nission Attn: Doctment Control Desk Washington, DC 20555 4'

SUBJECT:

Interim Report for Limerick Generating Station, Unit 2 .

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Belleville Washer Failures in Cutler Hararer MCCs Limerick Generating Station, Unit 2 I J

NRC Construction Permit No. CPPR-107

REFERENCE:

Telecon of PECo to NRC dated 4/15/88 FILE: QUAL 2-10-2 (SDR 6231-2) l r

Dear Sir:

i In ecmpilance with 10CFR Part 50.55Ce), we are hereby submitting l

an interim report of failures of, the Belleville washers in Cutler-Hanmer MCCs at Limerick Generating Station Unit 2. The Philadelphia Electric J

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• Company (PECo) discussed these failures by telephone with the USNRC Regional Office of Inspection and Enforcement on Apell 15, 1988, after  !

It was determined that the failures are reportable.

f On 10/21/87, during checkout for eteanliness of nonsafety-related  :

nutor control centers (MCC) our Architect Engineer (AE)/ Constructor  ;

Identified cracked Belleville washers. The washers are used at the  :

connection point between the vertical and horizontal bus sections for i the purpose of traintaining pressure on the connection. Our AE installed  ;

replacement washers supplied by Cutler-Hamrer on all Unit 2 r r'onsafety-related MCCs. Washers on MCCs comon to Unit 1 and 2 have not been replaced.

l After this discovery our AE inspected all Unit 2 safety-relatec MCCs which are of the same design and manufacturer, for similar washer failures and found no visible cracks.  :

Subsecuent to the failed washer discovery, samples of the failed washers and other supplied washers were sent to our Metallurgical ,

Laboratory to ascertain their tretallurgical charscteristics and [

i deterinine the probable cause for failure. Results of this examination l

are docurented in Metallurgical Laboratory Note No.87-293 dated f

March 11, 1988. The extinination concluded the washers failed due to I 6  !

I 8805200225 880513 8lf i PDR ADOCK 05000353 j j $ DCD i

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1 Intergranular decohesion due to hydrogen erbritticcent. The ecbrittlecent vas induced during the manufactut ing prccess, specifically the cleaning and plating operation, as a result of a deficiency in quality control by the manufacturer, in addition the lab discovered cracks that did not penetrate the surface coating cnd therefore surface visual examination in the fleId is not a reliable inspection method.

Although no failures have been identified to date on safety-related MCCs at Limerick Generating Station Unit 2, based on the laboratory's conclusion and the fact that the safety-related MCCs were nanufactured by the sane manufacturer, we believe the condition to be reoortable.

The renufacturer has been contacted and reauested to provide additional inforrat ion regarding instances of failures, and his evaluation of the entire problan including reconrendations.

A detailed report will be filed after the evaivat ton of the problen is completed and ccrrective action determined. It is expected that the detailed report will be canpleted by July 15, 1988.

Sincerely,

.& 5'

. , a m.~w DSM/ghr/05118802 Copy to: USNRC Site Resident inspector United States Nuclear Regulatory Comnission Region I 631 Park Aver.ue King of Prussia, PA 19L06