ML20004F908

Forwards Revised Response to Draft Power Sys Branch Position 8.3.5 Re Reactor Containment Electrical Penetrations

ML20004F908
Person / Time
Site:	Fermi
Issue date:	06/24/1981
From:	Colbert W DETROIT EDISON CO.
To:	Kintner L Office of Nuclear Reactor Regulation
References
EF2-53793, NUDOCS 8106260164
Download: ML20004F908 (3)

Text

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Mr. L. L. Kintner N p/,g -

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6 Division of Project Management Office of Nuclear Reactor Regulation Q

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S. Nuclear Regulatory Commission Washington, D. C.

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Reference:

Enrico Fermi Atomic Power Plant Unit #2 NRC Docket No. 50-341

Subject:

PSB Position (8.3.5)

Reactor Containment Electrical Penetrations

Dear Mr. Kintner:

Please find attached Detroit Edison's revised response to the draf t PSB position (PSB-2) on Reactor Containment Elect 1Acal Penetrations.

Sincerely, 7M f b

William F. Colbert Technical Director Enric Fermi Unit #2 RB/w OOl lll

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4' Juna 22, 1981 EF2-53793 Rev. A

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ATTACHMENT.

POSITION ON REACTOR CONTAINMENT PRIMARY ELECTRICAL PENETRATION PROTECTION

-The. Detroit Edison. Company Fermi 2 Project,.has made a review of the

-Reactor' Containment Primary Electrical. Penetrations. The main objective Lof this' review wassto-determine that the electricalipenetration1 0

assembliescare designed to withstand, without the;1oss of mechanical integrity, the ' maximum available. fault current versus time ' conditions that could occur,~given single random failures of circuit overload-

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. devices-as recommended by Regulatory Guide 1.63, Revision 1.

'" Electrical Penetration Assemblies in Containment Structures for

. Water-Cooled Nuclear Power Plants".

In making the review,'the fol?owing assumption was primary:

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-The I t characteristics of the penetration conductors as #urnished by Conax Corp. were used as a basis #or determining integrity. It is that the I t' curves as furnished by Conax Corp.

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-are conservative in nature and that the I t curve points are not necessarily r

1the points of damage to the mechanical integrity of the penetrations.

However,-in our. review, we followed this conservatism, giving additional assurance that-potential-damage ~to the penetration is thereby reduced to nilJif properly protected.

- -The lfollowing positions. are taken by Detroit Edison, based on the results of this review. These positions are in line with the guidelines set forth 'in Regulatory Guide'l.63..

For-low-energy penetrations, maximum fault current does not approach the 2I tsof the penetration conductor;'no, backup or redundant protection is provided.

On;1ow-voltage oower penetrations where maximum fault current versus time will i

exceed the I t of the penetration conductor (considering single random failure l-of the primary pcocection) backup protection will be provided by one of the two following methods:

1. cIf adequate backup pratection can be obtained from the feeder

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. position and the fault can be cleared in sufficient time to 2

prevent reaching the I t of the penetration conductor - no

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L additional ~ redundant protective devices will be provided.

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'Juna 22, 1981 EF2-53793 Rev. A 2.

Where the feeder position cannot provide adequate clearing time, an additional protective device, fuse or breaker'as necessary, will be provided.

~ There are only two medium voltage power penetrations. These are used for the Reactor Recirculation Pump Motor MG set output from the generator to

- the pump motors. In ?hese cases the primary protection is provided by tripping the main MG set motor drive incoming circuit breaker. positions.

- Backup protection is provided by tripping che generator field breakers.

-Proper relaying assures operati.on of the field breaker.

Loads 'to the primary containment not necessary for reactor operation, i.e.,

lighting and welding will be naintained in a deenergized condition.

Although every effort will be made to complete the installation of necessary-redundant devices in time for fuel load, we do commit to completing all such work by. time of the first refueling outage.

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