ML19274D897

Provides Results of Analysis Completed Per Safety Evaluation Supporting Amend 35 to License DPR-35.Discusses Fire Protection Issues,Including Prevention of Spread of Combustible Liquid Via Drains

ML19274D897
Person / Time
Site:	Pilgrim
Issue date:	02/20/1979
From:	Andognini G BOSTON EDISON CO.
To:	Ippolito T Office of Nuclear Reactor Regulation
References
NUDOCS 7902270190
Download: ML19274D897 (3)

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BOSTON EDISDN COMPANY GENERAL OFFICES aco BOYLSTON STREET S O ETO N. M AesACHueETTs o2199 February 20, 1979 C^ ",'j ,, " * ' * ' BECo. Ltr. #79-46 NUCLEAR OPERATIONS DEPARTMENT Mr. Thomas A. Ippolito, Chief Operating Reactors Branch #3 Division of Operating Reactors Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D. C. 20555 License No. DPR-35 Docket No. 50-293 Fire Protection

Dear Mr. Ippolito:

This letter advises you of the results of an analysis required to be completed per Table 3.2 of the Safety Evaluation supporting Amendment No. 35 to our operating license.

Item 3.2.5 Prevention of Spread of Combustible Liquid Fire via Drain Systems (4.8)

A study will be performed to determine the extent to which backflow valves need to be installed in the drain systems in any plant areas containing a large quantity of combustible liquid to prevent spread of a possible com-bustible liquid fire via the drain system.

BECo Response:

Summary A detailed analysis of the drain systems for areas containing large quantities of combustible liquid was performed to am 'ress the staff concern reflected in section 4.8 of the SER. These areas include 1) Reactor Building Quandrants which contain the HPCI and the RCIC Pumps 2) The Recire M.G. Sets at el. 51' of the Reactor Building and 3) Hydrogen Seal Oil System in the Turbine Building.

The area analyses described below prove that the existing floor and equipment drain system with theit sumps are desigted to prevent the spread of combust-ible from one area into ano*.her. No additional protection in the form of backflow valves will be required.

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BOSTON EDISON COMPANY Mr. Themas A. Ippolito, Chief Fc'oruary 20, 1979 Page 2

1) Reactor Building Ouadrants The HPCI turbine and the RCIC turbine are located in spatially separated Reactor Building Quadrants. The Reactor Building Equipment Drain Sump, Reactor Building Floor Drain Sump and the drainage block valves (normally " closed" and " fail closed") are located in the Northwest quadrant which is adjacent to HPCI Turbine Room. Each quadrant also has a high level switch to annunciate flooding. This level switch does not open the quadrant drain valves. The Reactor Building Equipment Drain Sump and Floor Drain Sump each has sufficient capacity (468 gal.) from high level alarm to overflow,to contain the entire combustible liquid from the HPCI turbine (225 gal.). Each sump has a high level capacity of 411 gal., which when added to the overflow capacity of 468 gal. would give a total capacity of 879 gal. The sumps are located below the lowest finished grade. In the event either sump is filled to overflow capacity, the overflow is directed to the other sump. In the unlikely event that all quadrant drain valves were incorrectly positioned 'open',

the overflow height of the sump at el. (-) 21'-2" would be safely below the lowest HPCI quadrant floor drain located at el. (-) 19'-9" and also below the lowest floor drain connected to the system (Torus Room South-east Corr) at el. (-) 20'-4".

Additionally the Reactor Building block valve sump is located in the same quadrant and is connected by a 4" line to the Reactor Building floor drain Sv This allows valve leakage to be returned to the floor drain sump. 1v :k valve sump has sufficient capacity (900 gal.) to contain the entire contents of the floor drain sump.

The RCIC turbine is located in the Southwest quadrant and contains a significantly smaller quantity of lubricating oil (20 gal.) than HPCI Turbine. The closed block valve will insure that no lubricating oil will enter the sump. In the unlikely event the block valve were left open during a fire event, the connection of the RCIC drain to the Reactor Building equipment drain sump with a 12" water seal insures the nonprop-agation of fire from RCIC quadrant to any other area.

The Reactor Building Quadrant drainage system was also analyzed using a Field Test to verify that no cross connections exist which cauld allow inadvertant transfer of combusti~ ole lube oil spills between quadrants.

2) The Recirc M.G. Sets are located at el. 51'-0" of the Reactor Building.

Each M.G. Set hydraulic coupling contains 700 gal. of oil. Curbs are provided to contain the combustible liquid. The drain system for this room has an installed oil separator which directs the oil waste to a collection point located in a non-safety related area in the Reactor Building Auxiliary Bay. The oil free waste from the oil separator is directed to the neutralizing step for treatment and release.

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BOSTON EDISON COMPANY Mr. Thomas A. Ippolito, Chief February 20, 1979 Page 3

3) The hydrogen seal oil system is located at el. 23'-0" of the Turbine Building and contains 410 gal. of oil. The unit is curbed to collect oil leakage. If the oil should escape the curbed area, it would enter the NW floor drain system. This drainage system is separate from the Turbine Building equipment or floor drain collection system. The NW floor drain system has an oil separator located outside of the fire zone. The oil from the separator is removed by a draw-off in the Radwaste Building at el. (-) l'-0". The oil free waste is directed to the sewage waste ejection sump.

If you have any frrther questions on this subject please contact us at your convenience.

Very truly yours,

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