ML20128R065

Potential Significant Deficiency Rept SD-79 Re Westinghouse 7300 Protection Sys.Initially Reported on 850408.S&W Redesigning Configuration.Next Rept Will Be Submitted by 850619

ML20128R065
Person / Time
Site:	Millstone
Issue date:	05/08/1985
From:	Opeka J, Sears C NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
F0735A, F735A, SD-79, NUDOCS 8506040394
Download: ML20128R065 (2)

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(20a 665-5000 May 8,1985 Docket No. 50-423 F0735A Dr. Thomas E. Murley Regional Administrator U.S. Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA.19406

Dear Dr. Murley:

Millstone Nuclear Power Station, Unit No. 3 Reporting of Potential Significant Deficiencies in Accordance with 10CFR50.55(e):

Westinghouse 7300 Protection System (SD-79)

In an April 8,1985 telephone conversation between your Mr. T. Rebelowski and our Mr. G. Olsen, Northeast Nuclear Energy Company reported a potential significant deficiency in the construction of Millstone Unit No. 3 in accordance with 10CFR50.55(e).

The potential significant deficiency involves the Westinghouse 7300 protection system.

Interconnection cabling for the 24 volt DC' power supply system between the 7300 protection rack sets was designed and installed as nonsafety-related cable within the same cable tray. Since the 24 volt DC is used as an auctioneered power supply for the 26 volt DC power supply, the cabling should have been safety-related and installed in accordance with Millstone Unit No. 3's separation criteria. Hence, this represents a significant deficiency in the final design for Millstone Unit No. 3.

Our architect-engineer, Stone & Webster Engineering Corporation, is in the process of redesigning this configuration. We will provide you with an update on this matter by June 19,1985.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY i

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3. F. Opeka Senior Vice President L

By: C. F. Sears Vice President 850604039485050g23 PDR ADOCK 0500 10 [

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