ML20087N198

Potential Significant Deficiency Rept SD-50 Re phase-to- Phase Electric Fault in Motor Control Ctr Supplied by Gould,Inc.Initially Reported on 840116.All Uninsulated Cable Adapters Removed.Next Rept by 840620

ML20087N198
Person / Time
Site:	Millstone
Issue date:	03/23/1984
From:	Counsil W NORTHEAST UTILITIES
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
F0493A, F493A, SD-50, NUDOCS 8404030209
Download: ML20087N198 (2)

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HARTFORD. CONNECTICUT 06141-0270 none,eas, evei seawa cowa=, (203) 666-6911 esamt.eas, es>ckf aA tadaGv Crwaare March 23,1984 Docket No. 50-423 F0493A Dr. Thomas E. Murley Regional Administrator Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406

Reference:

(1) W. G. Counsil letter to T. E. Murley, F0467A, dated February 15,1984.

Dear Dr. Murley:

Millstone Nuclear Power Station, Unit No. 3 Reporting of Potential Significant Deficiencies in Design and Construction:

Phase-to-Phase Electric Fault in a Motor Control Center (SD-50)

In a January 16, 1984 telephone conversation between the NRC Resident inspector, Mr. T. Rebelowski, and our Mr. D. B. Vail, Northeast Nuclear Energy Company (NNECO) reported a potential significant deficiency in the construction of Millstone Unit No. 3 as required by 10CFR50.55(e).

Subsequently, this was followed up with another telephone conversation with your Mr. T. Elsasser on January 17, 1984. The potential significant deficiency involves a phase-to-phase electrical fault which occurred in a motor control center (MCC) supplied by Gould, Inc. while a technician was testing with a clamp-on ammeter. The fault occurred between adjacent phases of the uninsulated cable adapters used to terminate oversized cables to MCC circuit breakers and starters.

We have initiated action to remove all uninsulated cable adapters on all safety-related and nonsafety-related MCC circuit breakers and starters. The criteria used for terminating the field cables to MCC breakers and starters is as follows:

1. Where the cable size is small enough to fit a breaker or starter, the cable will be terminated directly onto the breaker or starter.

2. Where the cable size is too large to fit a breaker or starter, the cable will be spliced down to We largest size cable able to fit onto the breaker or starter. O 8404030209 840323 PDR ADOCK 05000423 S PDR  %(y0

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We are currently awaiting the seismic qualification data from Gould, Inc. with regard to the cable adapters. Once this data is received, it will be reviewed by our architect-engineer, Stone & Webster Engineering Corporation, and Northeast Utilities.

Based on a discussion between Mr. R. Young and Mr. T. Rebelowski, this update is being provided on March 23,1984 rather than March 15,1984. We are not able to provide you with a final report at this time and are requesting an extension until June 20,1984.

Very truly yours,

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• W.'G. Counsil Senior Vice President cc: Mr. R. C. DeYoung, Director Division of Inspection and Enforcement U.S. Nuclear Regulatory Commission Phillips Building 7920 Norfolk Avenue Bethesda, MD 20014