ML20079H178

Final Deficiency Rept U-57 Re Cutler Hammer Control Switches.Initially Reported on 830627.Comsip,main Control Board Vendor,Directed to Discontinue Practice of Bending Switch Contact Block Terminal Lugs

ML20079H178
Person / Time
Site:	Callaway
Issue date:	01/10/1984
From:	Schnell D UNION ELECTRIC CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
U-57, ULNRC-720, NUDOCS 8401230350
Download: ML20079H178 (2)

Text

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UNION ELECTRIC COMPANY tsOf GRATIOT STREET ST. LOulE MassOURI coNALD SP. .CHN.LL .ON 9 .

vi. . .... e January 10, 1984 er. 6ou. ui..oum .. ..

Mr. James G. Keppler Regional Administrator U. S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 ULNRC-720

Dear Mr. Keppler:

FINAL 10CFR50.55(e) REPORT U-57 CUTLER HAMMER CONTROL SWITCHES CALLAWAY PLANT On June 27, 1983, Union Electric informed the NRC Region III office of a potential 10CFR50.55(e) regarding Cutler Hammer E-30 control switches utilized in the main control board.

The rear contact block casings of certain switches were found to be cracked, which could have caused open circuits in the switches.

Union Electric has determined that the damage was caused by the main control-board vendor's (Comsip) procedure of bending terminal lugs after attachment to the switch contact block. The switch is structurally adequate to withstand the normal loads imposed by the weight and tension of terminated conductors.

The main control board vendor has been directed to discontinue the practice of bending switch contact block terminal lugs and is currently supplying 90 degree pre-bent terminal lugs as required. Union Electric feels that the use of the 90 degree lugs will prevent recurrence of the problem.

Union Electric has completed a 100 percent inspection of Cutler Hammer E-30 switches on the main control board. No broken switch contact blocks were found other than the nine previously identified and replaced. In addition, normal start-up testing has not identified any recurring problems that can be attributed to broken contact blocks on the E-30 switches.

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Regarding 10CFR50.55(e) reportability, Union Electric feels that a switch failure resulting from a broken contact block could have been adverse to plant safety, had it gone undetected.

Therefore, we consider this item reportable under the guidelines of 10CFR50.55 (e) . This is Union Electric's final report on this subject.

Very truly yours, Donald F. Schnell MAC/DWC/sla cc: J. E.-Konklin, NRC Region III Richard DeYoung, Director I&E NRC Resident Inspectors, Callaway Plant (2)

Missouri Public Service Commission