ML20005B019
| ML20005B019 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 06/30/1981 |
| From: | Colbert W DETROIT EDISON CO. |
| To: | Kintner L Office of Nuclear Reactor Regulation |
| References | |
| EF2-53793-REV-B, NUDOCS 8107060225 | |
| Download: ML20005B019 (3) | |
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2000 Second Avenue f[b June 30, 1981 EF2-53793, Rev. B Mr. L. L. Kintner Division of Project Management Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D. C.
20555 I
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 attache <' Detroit Edison's revised response to the draft PSB position (PSB-2) on Reactor Containment Electrical Penetrations.
Sincerely, William F. Colbert Technical Director Enrico Fei ni bait #2 RB/vms cc:
B. Little (EF2)
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0107060225 81 PDR ADOCK 050 1
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June 30, 1981 EF2-53793 Rev. B ATTACEMENT POSITION ON REACTOR CONTAINMENT PRIMARY ELECTRICAL PENETRATION PRCTECTION The Dettoit Edison Company Fermi 2 Project, has made a review of the Reactor Containment Primary Electrical Penetrations.
The main objective of this review was to 6 termine that the electrical penetration assemblies are designed to withstand, without the loss of mechanical integrity, the maximum available fault current versus time conditions that could occur, given single random failures of circuit overload 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 following assumption was primary:
The 12t characteristics of the penetration conductors as furnished by Conax Corp. were used as a basin for determining integrity. It is 2
realized, however, that the 1 t curves as furnished by Conax Corp.
2 are conservative in nature and that the I t curve points are not necessarily the 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 nil if properly protected.
The following 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 1.63.
For low-energy penetrations, maximum fau? t current does not approach the 21 t.-of the penetration conductor; nct backup or redundant protection is provided.
On low-voltage power penetrations where maximum fault current versis time 2
will exceed the 1 t of the penetration conductor (considering single random i
i failure of the primary protection) backup protection will be provided by one of the two following methods:
1.
If adequate backup protection can be obtained from the feeder position and the fault can be cleared in sufficient time to 2
prevent reaching the I t of the penetration conductor - no additional redundant protective devices will-be provided.
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June 30, 1981 EF2-53793 Rev. B 2.
Where the feeder position cannot provide adequate' clearing time, an additional protective device, fuso 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 these cases the primary protection is provided by tripping the main MC set motor drive incoming circuit breaker positions.
Backup protection is provided by tripping the generator field breakers.
Proper relaying assures operation of the field breaker.
Loads to the primary containment not necessary for reactor operation, i.e.,
lighting and welding will be maintained in a deenergized condition.
l The installation of the necessary redundant devices will be completed in l
time for fuel' load.
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