ML17252A046

Diesel Generator Cooling Water Flood Protection

ML17252A046
Person / Time
Site:	Dresden
Issue date:	07/20/1976
From:	Silver R Office of Nuclear Reactor Regulation
To:	Goller K Office of Nuclear Reactor Regulation
References
Download: ML17252A046 (2)

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Li UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 July 20, 19 76 Docket No. 50-249 Karl R. Goller, Assistant Director for Operating Reactors, DOR THRU: Dennis L. Ziemann, Chief, Operating Reactors Branch #2, DOR f;/!...y

. DRESDEN UNIT 3 - DIESEL GENERATOR COOLING WATER FLOOD PROTECTION Introduction By letter of July 16, 1976, Commonwealth Edison Company (CE) informed us that the Dresden Unit 3 submersible diesel generator cooling water pwnp had failed and could not be repaired or replaced within the seven day period allowed for continued operation with one diesel generator out of service (Specification 3.9.B.2.). The seven day period ends Tuesday, July 20, at 5:30 pm. The replacement pump, ordered about a year ago., as a spare, is not expected to be available until about August 30. CE stated that the cooling pwnp would be replaced temporarily, with the nonsubmersible pwnp which had been originally used. The original pump had been replaced by the submersible pump as part of a flood protection modification to assure co"oling of the Unit 3 diesel would be available if flooding of the cribhouse occurred. CE has per-formed a review in accordance with the requirements of 10 CFR 50.59 and has concluded that the temporary replacement does not involve a change in t~e technical specific~tions or an unreviewed safety question.

Discussion Prior to* replacement of the original Dresden 3 .and Dresden 2/3 diesel generator cooling water pumps with submersible pumps, the possibility existe.d that a flood in the cribhouse could fail these pumps and*

therefore, fail the diesel generators. As an interim fix, reported to the NRC by CE letter of August 23, 1973, CE committed to shutting down the reactor in the event of flooding in the cribhouse and connecting a manual hose type intertie from the fire water system to the cooling

• water supply of the 2/3 diesel generator. The temporary arrangement now planned by CE would be better than the interim fix previously reviewed

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'Karl R~ GoUer:

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in. that** an opetab1.e *subnie:rsible pump'*will":be avf.l.ilable to supply cooling

. water to the 2/3 diesel.

• in. :addition, the Unit 2 *diesel which is cooied

'by a submersible pump" could be crossti,ed *'to the Unit 3 emergency .busses.

_CE has also ccinllitltted .to* shutdm~ Uiii t. 3 ff. crib4ou5e flooding occurred

• h~fore the new* s.Ubmersib~e *pum1> is . installed~ A level - alarm wo:uld-warn

.. of flooding before th~ wate:f level' reached *tne 'pump° eievation.

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_:. "ilased,*, on th~ ab.ave conslder_atioj'is, I *hav$ co~eluded that th6 meas.ures,

- planne.d by CE are acceptable as an* interim actfo.n ,prior to installation

• of a repaired or.replacement'sul>mersibie pWnp; that the actions plann~d

-*by CE are not in *conflic.t with the. tecllnical specifications and .that

• the temporary 'measures wfll_ be sUbstantiaHy better than the t~mporary measures previou5ly reviewed_*.. Therefore,** I *conclude that* operation wiU1i/,*.

the nonsubmers~ble p~. on :a 'teiirp,*orary- basis does not .involve . an _unrevfewed safety *question **and no- licensin~g_, actJOn

• iS required* . .

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Richard D. Silver

• Operating Reactors Branch-.#2 Divisio:n of Operating Reactors cc:

• V. Stello-.

T. Carter DISTRIBUTION*

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1974~'520.UHS Form ~-318 (Rev. 9-53) AE<;:M .02'0. ' - U.* S: PRINTING 0PP1CEI .