ML20050B016

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Discusses Resolution of Hydrological & Geotechnical Engineering Branch Concerns Re Availability of Installed Sump Pumps in Dry Cooling Towers During Intense Precipitation Events.Portable Pump Will Be Provided
ML20050B016
Person / Time
Site: Waterford Entergy icon.png
Issue date: 03/30/1982
From: Maurin L
LOUISIANA POWER & LIGHT CO.
To: Tedesco R
Office of Nuclear Reactor Regulation
References
W3P82-0652, W3P82-652, NUDOCS 8204020501
Download: ML20050B016 (2)


Text

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  • NEW CRLEANS LOUGANA 70174 * (5041 366 2345 UT7L E iE L.V. MAURIN C) esident Nuclear Operations March 30, 1 .

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- A29.20 APR 011982* T 9-Mr. Robert L. Tedesco Assistant Director of Licensing 5 ,g eg 7 U. S. Nuclear Regulatory Commission N g

Washington, DC 20555 g O (4

SUBJECT:

Waterford SES Unit No. 3 Docket No. 50-382 Resolution of Hydrology Branch Concerns In SER 3ection 2.4.2.3, the Hydrological and Geotechnical Engineering Branch (HGEB) outline a potential problem dealing with the availability of the in-stalled sump pumps in the dry cooling towers during intense precipitation events.

These pumps are required to prevent immersion of safety related equipment in the area, yet are not seismic Category 1.

Therefore, in order to satisfy the HGEB's concern that a pump be available for a Standard Project Storm (SPS) coincident with an OBE (Operating Basis Earth-quake), we will provide a portable pump. We have calculated that a pump of 100 gpm capacity with sufficient head to pump over the cooling tower wall is sufficient to ensure that SPS flooding in the cooling tower area does not impact safety related equipment. (Attached is a discussion demonstrating that 100 gpm will be adequate.) This pump will be stored within the Nuclear Plant Island Structure (NPIS) so as to minimize the impact on the pump of an OBE.

In addition, the pump will be stored on pallets placed away from any non-seismic Category I equipment which could fall and damage the pump. Furthermore, this pump will be included in the equipment surveillance testing program. The testing will include a demonstration at least once per refueling that the pump will circulate water.

As part of our emergency procedures, we will include provisions for switching the power supply of the installed pumps to the emergency bus within 1/2 hour of a loss of offsite power and provisions for emplacing the portable pump with-in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of a seismic event if the installed pumps fail.

These procedures, as well as details of the testing program, will be available priot to fuel load.

Ver truly yours,  ;

M L. V. Maurin LVM/RMF/pmw cc: E. L. Blake, W. M. Stevenson, S. Black, R. Gonzales

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8204020501 820330 PDR ADOCK 05000382 F PDR L

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j UHS FLOOD PREVENTION

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PORTABLE EMERGENCY PUMP CAPACITY 4

Since the depth of water in the UHS area is 1.62 ft. at the end of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> with

{ no pumping, it is not necessary to provide a pump with enough capacity to instantaneously handle the maximum subsequent rainfall intensity. . If it is

! sized to handle the average rainfall rata of hours 7 through 12, the maximum

- depth could rise to 1.66 feet, and would drop back to 1.62 ft. again at the end of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and continue to drop thereafter.

Since the PMP is 30.7 in for 6 hr. and 34.6 in f.c 12 hr.,'and the SPS is being i conservatively taken as 60% of the PMP, the total rainfall in hours 7 through 12 is 2.34 fe. The average rate of water inflow is 100 gpm. Assuming the max-

! 1 mum rate c2 rainfall is 38% of 2.34 in. in one hour, this is equivalent to 225 gpm. If a 100 gpm pump is used, the 125 gpm deficit for one hour results

. in only a 0.04 ft. increase in depth. Thus the 100 gpm capacity is sufficient to prevent flooding of the MCC grounding bus if the pump is activated within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. 3 If no pumps are in operation for the first 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> of the SPS, the water level would rise to 1.83 ft. Activation of the 100 gpm emergency pump at 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />

would still be adequate to prevent flooding of the vertical hus at 1.90 ft. above the floor. *

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