ML18081A461

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Requests Preparation of Amend to FSAR to Reflect Response to NRC Position Re Sump Design.Objective Is to Decrease Velocities to Acceptable Level & to Insert Vortex Suppression Devices
ML18081A461
Person / Time
Site: Salem 
Issue date: 10/12/1979
From: Parr O
Office of Nuclear Reactor Regulation
To: Mittl R
Public Service Enterprise Group
References
NUDOCS 7911010599
Download: ML18081A461 (3)
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Docket File~~lJt LWR #3 File WGammill act 1 2 1979 DV.assa 11 o DRoss SVarga

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Docket NQ. 50-311

  • FWilliams OP arr ADromerick

Mr. R. L. Mittl, General Manager Licensing and Environment Engineering and Construction Depar~ment Public Service Electric and Gas Company 801 Park Place Newark~ New Jersey 07101

Dear Mr. Mittl :

MRushbro6k (w/extra copies)

RMattson SHanauer

  • JKni ght RTedesco RDeYot,rng VMoore MErnst RDenise ELD

SUBJECT:

AN ASSESSMENT OF THE SALEM, UNIT 2, CONTA_INMEN:T SUMP We have previously made a determination that in the case ot duplicate-or replicate plants, only the first of a*series need be teste~ to demonstrate adequate performance of the containment sump in the post-LOCA recirculation mode.

As Salem, Unit 1, had performed a test, it has been presumed that Salem; Unit 2, would not have to pe~form one.

However, during a recent review of all containment.sump tests, it was found. that the Salem. Unit l, test had been accepted as an appropriate demonstration of ~ump adequacy, primarily on the basis that the test crew had seen no vortex formation. A review of the test plan and data sheets indicated that only a 30 second test had been performed on each pump with the pumps throttled to 50 percent of design flow.

Deficiencies in pump NPSH were indicated when the loss data were projected to the design and runout flow. *In summary. neither vortex control nor adequate NPSH had actually been demonstrated by the Salem, Unit l, tests.

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In light of the abo~e, we have re-reviewed the Salem, Unit 2, containment sump design.

Our review was based on the information in the FSAR, a set of drawings of the containment sump provided by you on August 20, 1979,and our experience in following the testing and development of a variety of *contain-ment sump designs.

The containment sump screen in tha current Salem, Unit 2, design consists of an inverted metal box or c~ge located over the sump pit. The sides are perforated with 3/8 11 holes located on L'l/2 11

.centers. Conservative analysis by the NRC staff indicates a 5.5 ft. head loss through these holes at runout flow (4500 gpm per pump) with 50 percent blockage.* Available NPSH would be less than required fqr the pumps under kt.

this condition.

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  • 1 Mr. R. OCT 1 2 1979 Experience indicates that air*and debris entraining vortices would.form~

from the water surface to the holes in the present design.

Debris could cau~e progressive blockage of the holes.

Entraine~ air would be expected to be dra\\'Jn into the safety *system by either of two mechanisms:

( l ) the high downward velocities in the cage and sump pit would ovetcome the potential for bouyan*t separation, and (2) selective blockage of the cage would force a rotational pattern inside resulting in nn air entraining vortex penetrating to the outlet pipes. _Both mechanisms have been observed during other sump tests involving designs with similar or more conservative design parameters.

In order to remove these apparent potential problems, we require that the Salem~ Unit 2, containment sump desigri b~ re-~valuated and modified as necessary~ The objective is to decrease velocities to an a~ceptable level and to insert vortex supp~ession devices to keep rotational.

patterns from forming.

As you know~ the NRC and the nuclear industry have been evaluating this matter over the past several years. Although continuing, this effort has resulted in evaluated and tested containment sump des1gns that appear to minimize the potential for the problems 1ndicated above.

Several such sump designs have been reviewed and approved by the NRG staff on recent operat-ing applications.

We recommend that you.review the work performed by the NRG and the nucl'ear industry related to this matter, discuss it with us as may be necessary to reach full understanding, and submit information to substantiate your design or propose a modification to the Salem, Unit 2, sump design which.will prov1de assurance that the sump will perform its

  • intended function.

We require that any proposed modifications be imple-mented prior to a decision concerning the issuance of an operating license.

In addition, we requ\\re that you perform a model test of the final contain-ment sump configuration, which will provide assurance that there-is a very limited likelihood of adverse performance.

The model testing pr.ogram shalr be subject-to our approval, and scheduled for completio-n prior to the first

$Cheduled refueling. Should the model *test indicate requirements for further modifications, they must be made prior to start-up after the first refueling.

Accordingly, we request that you amend your FSAR to cl earJy sta,te your intent regarding conformance with our position *as stated above..

Please-inform us after receipt of this letter, of your schedule for providing the information described above.

Sincerely, Origqnal Signed by Olan Parr

  • Olan D. Parr, Chief Light Water Reactors, £ranch No. 3

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NJ1C FORM 318 (9*76) NRCM 0240 U.8. OQVICRNN&NT PIUHTtNG*Ofl'fl'l~I:: 1971 - ZtlB+ - 789

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Mr

  • R. L. M it t l, Ge n e r a l Ma n a g e r Licensing and Environment Engineering and Construction Depar-tment Public Service Electric and Gas Company 80 Park Place
Newatk, Ne~ Jersey 07101 cc: *Richard Fryling, Jr., Esq.

Assist ant General Counsel Public Service Electric & Gas Company 8 0 Pa rk P l a c e Newark, New Jersey 07100 Mark Wetterhahn, Esq.

Conner, Moore & Caber 1747 Pennsylvania Avenue, N.W.

Suite 1050 Washington, D.C.

20006 Mr. Leif J. Norrholm U. S. Nuclear Regulatory Cormiission Region I Drawer I Hancocks ~ridge, New Jersey 08038.

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