ML19347E615

Forwards Util 810427 Memo Re Concerns on Closing of Switchboard Breaker W/O Dc Control Power.Memo Provides Methods That Could Be Utilized to Perform Task

ML19347E615
Person / Time
Site:	Waterford
Issue date:	05/12/1981
From:	Maurin L LOUISIANA POWER & LIGHT CO.
To:	Trehan N NRC
References
W3P81-1204, NUDOCS 8105130132
Download: ML19347E615 (3)

Text

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.. . fo-SP I l OUISIANA 142 crunouce stater P O W E R & L i G H T! P O. box 6008 . NEW ORLEANS. LOU'SIANA 70174 . (504) 366-2345 l

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W3P81-1204 3-A12.05 3-A1.01.04 3-M1

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SUBJECT:

Closing the Switchyard Breaker O - U with Loss of DC Control Power

Dear Mr. Trehan:

Please note tha attached letter referring to the subject question that ,

was asked ,at the Power Systems Branch Review Meeting on April,20,1981.

The letter states some of the reasons why Louisiana Power & Light would be very concerned about the ci,*9'.ng of a switchyard breaker without DC control power. Purthennore, m letter provides methods, from two different manufactures that could e utilized to perform the subject task.

If you have any additional questions or require more information on this subject, please contact E. J. Senac at 504-363-8781.

Yours very truly, L. V. urin Assistant V'.ce-President Nuclear Op ;ations LVM/EJS/dt Attachments cc: 7. J. Drumond, M. I. Meyer, R. W. Pr.idos , T. P. Brennan, g i D. Sandiforth, J. Hart, Central Records, Nuclear Records p00/

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April 27, 1981 RECEIVED NUCLEAR RECOROS Mr. T. P. Brennan Waterford #3 APR 281981

Dear Tim:

ILN: M Aff 3 -

In regard to the question, "other means of closing the Switch-yard breaker if the DC control power supply for the closing coil of the circuit breaker fails "I have the following response.

The primary purpose of a circuit breaker is to provide a means of opening a circuit. Breakers are designed with a stored energy system that provides the capability of opening a closed breaker by releasing a latch (electrically or manually). No provisions are normally made to provide for closing after loss of control power. This DC control power is also used by the protective relaying. Thus, closing of a circuit breaker after loss of DC control power would be quite risky since all protective relaying would be ineffective.

We have, however, checked with the breaker manufacturers and there is a procedure which can be utilized to close the breaker w_thout DC control power. In the case of the McGraw Edison IPO OCB there is a manual lever on the closing solenoid that will operate the breaker providing there is still pressure in the accumulator.

If there is no pressure, a portable AC source will be needed to run the pumping equipment (this is a hydralic system). They also indicated that the accumulator can be manually pumped, but as of yet we are not certain of the time required for this manual pumping.

In the case of the Westinghouse IPO OCB there is a manual operate button on the pilot valve (this is a. pnuematic system) that can be used to close the breaker providing there is sufficient pressure to accomplish this. Westinghouse indicates that at a leakage rate of 2 to 5 psi per hour, the breaker could be operated as described above from 10-20 hours'after loss of power. If there is insufficient pressure to close the breaker, the tanks could be pressurized using a bottle of dry air or nitrogen. There ia no means provided to manually pressurize the tanks.

On both the McGraw-Edison and the Westinghouse breakers this procedure must be repeated for each phase since each phase has an independent mechanism.

.. Irr .- T . P . B r o n n e n April 27, 1981 Page 2 If we are required to include such a procedure in our operating instructions we would like the opportunity to participate in the writing of any document because of the safety considerations of closing a breaker over which we have no control. This is not a normal operating practice.

Yours very rul

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• W. J. Lan e WJL/wam cc: J. J. Saacks G. M. Woods R. T. Carter R. P. Taylor e

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