ML19329G309

Followup Deficiency Rept Re Loose Limit Switches on GE Circuit Breakers.Caused by Mounting Screws Backing Out. Screws Will Be Secured W/Std Strength lock-tite & Insp Will Be Revised

ML19329G309
Person / Time
Site:	Shoreham File:Long Island Lighting Company icon.png
Issue date:	07/01/1980
From:	Novarro J LONG ISLAND LIGHTING CO.
To:
References
SNRC-483, NUDOCS 8007140390
Download: ML19329G309 (3)

Text

f. m LONG ISLAND LIGH TING COM PANY CBC@

. fpfa.was, sf SHOREHAM NUCLEAR POWER STATION _

P.O. BOX 618, NORTH CP JNTRY ROAD e WAQiNG RIVER. N.Y.11792 SNRC-483 . .

July 1, 1980 Mr. Boyce H. Grier Office of Inspection and Enforcement, Region 1 U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406 LONG ISLAND LIGHTING COMPANY SHOREHAM NUCLEAR POWER STATION - UNIT 1 DOCKET No. 50-322

Dear Mr. Grier:

On February 6, 1980, in accordance with 10CFR50.55 (e), we re-ported verbally to Region 1 a deficiency with limit switches associated with General Electric 4160 volt circuit breakers.

A 30 day written report of this deficiency was submitted on March 5, 1980 (Ref. SNRC-466). This letter serves as a follow-up report.

Description of Deficiency The 4160 volt circuit breakers are General Electric type 1200 and 2000 ampere magne-blast breakers with ML-13 mechanisms, as manufactured by GE in their Philadelphia facilities.

During field checkout of the subject circuit breakers, it was noted that various limit switches on several breakers had be-come loose during operation of the breakers. The breakers had been recently returned by GE after rework for other deficiencies (Ref. SNRC-335, November 17, 1978). Those breakers surveyed and found to have this deficiency had undergone an average of 32 to 125 operations since their return to Shoreham.

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8007.140 39 o cc.nu

Mr. Grier ,

July 1, 1980 Page Two The loose switches were caused by backing out of the mounting screws. This enabled the limit switches to back away from their operating levers and permitted the limit switch contacts to re-turn to their normally open state. The resulting loss of con-tinuity in the breaker control would result in the inability of the breaker to close.

This deficiency was noted on safety and non-safety related breakers. However, circuit breakers presently installed in non-safety related cubicles have been qualified for Category I use, and therefore, circuit breaker substitutions may be made.

Routine breaker inspections do not require limit switch inspec-tion.

Failure of a Category I breaker to close will prevent. actuation  ;

of safety related equipment.

Corrective Action General Electric engineering and quality assurance have been ap-prised of this problem.

General Electric has informed LILCO that the switches used on the Shoreham breakers are standard and have been in use on the ML-13 mechanisms for over 15 years with excellent field experi-ence. Presumably the loosening of the switches, initiated as 1 result of vibration during the handling and shipping of the breakers to and from the factory, caused deterioration during subsequent operations.

General Electric does not routinely use adhesives, such as Lock-tite, to secure the mounting screws for these switches. However, as a result of our discussions with them, they have concurred with its use in our application.

Corrective Action to Prevent Recurrence The mounting screws of all limit switches of safety and non-safety related 4160V General Electric Type 1200 and 2000 ampere magne-blast breakers will be secured in place with standard strength lock-tite. Station breaker inspection procedures will be revised to re. quire inspection and, as necessary, service of the limit switches.

Mr. Grier July 1, 1980 .

Page Three Date of Full Compliance . .

The work involving application of Lock-tite and tightening of the limit switch screws will be completed by December, 1980.

Very truly yours, crl;i:::1 -9 ri by' l',1 P.1:0'ic.S J. P. Novarr'o

• Proj ect Manager Shoreham Nuclear Power Station ADMf/mt cc: Mr. Victor Stello, Director NRC Office of Inspection and Enforcement p/ Division of Reactor Operations Inspection Washington, D.C. 20555 cc: Mr. J. Higgins Site NRC Trailer bec: Distribution 14 SR2/Eng. File A21.500 e

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