ML18082A014

Submits Design Concept in Response to Paragraphs 3.1.27(1) & 3.1.29(2) of 780228 Fire Protection Safety Evaluation. Proposes to Wrap Channel B Cables w/2 Inches of Kaowool Blanket Matl.Diagrams Encl

ML18082A014
Person / Time
Site:	Rancho Seco
Issue date:	03/03/1980
From:	Walbridge W SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Reid R Office of Nuclear Reactor Regulation
References
NUDOCS 8003110657
Download: ML18082A014 (5)

Text

e !~~~NICIPAL

• UTILITY DISTRICT D 6201 S St"* Bo> 15830, S*crnmooto, c,1;1om;, 95813, (916) 452-3211 March 3, 1980 Director of Nuclear Reactor Regulation Attention: Mr. Robert W. Reid, Chief Operating Reactor, Branch 4 U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Docket No. 50-312 Rancho Seco Nuclear Generating Station, Unit No. 1 Fire Protection Modifications Fire Area 47 and 49

Dear Mr. Reid:

In two separate letters dated January 30, 1980, the District committed to rerouting Channel B cables associated with the high pressure injection pump out of Fire Area.47, corridor to the (-) 47 1 -0 11 elevation of the auxiliary building, and Fire Area 49, west containment penetra-tion valve.area. This commitment was made in response to Paragraphs 3.1.27(1) and 3.1.29(2) of the Fire Protection Safety Evaluation Report (SER), attached to License Amendment 19, dated February 28, 1978 .

. The modification insured safe shutdown and cooldown for a normal line-up of the high pressure injection system during a design basis fire. The normal line-up is with both high pressure injection pumps and make-u~ pumps in service. However, the staff has raised questions about the adequacy of the design when the 11 B11 high pressure injection pump is out of service and the make-up is operating as the 11 8 11 high pressure injection.pump. This operating line-up would have both channels of the high pressure injection system in the same fire area and capable of being damaged by a fire. To provide adequate protection in this situation, the District proposes to wrap the channel 11 B11 cables associated with the high pressure injection pump with 2 inches of Kaowool blanket material as shown in Figure 1.

Kaowool blanket was developed by Babcock & Wilcox Company's Refractories Division. It is an alumina-silica material with low thermal conductivity. Fire tests have been conducted by Babcock & l*~ilcox, Bechtel Power Corporation, and Georgia Power and certified by Underwriters Labs, Inc. The tests were conducted in a natural gas-fired furnace. The furnace was heated according to the heat rate designated in ASTM E-119 and involved complete engulfment fires. The test results indicated that wrapping cable trays with two inches of Kaowool will orovide at least 40 minutes of protection.

AN ELECTRIC SYSTEM SERVING MORE THAN 600,000 !N THE HEART OF CAL!FOl~N!A

Mr. Robert W. Reid

• March 3, 1980 The design basis fire in Fire Area 49 is a 250°F, 15-minute fire. Based on test data, the Kaowool blanket can provide protection for at Jeast 40 minutes from an ASTME-119 fire which has a geak temperature of 1613 F in 40 minutes, and an average temperature of l205 F. This indicates adequate margin between the capability of the design and the worst conditions expected due to a design basis fire. Therefore, the*

District 1 s modification assures operation of the high pressure injection system with a design basis fire in Fire Area 47 and 49.

The District requests that the NRC comment and/or approve this design concept by March 20, 1980, to prevent any delay in plant start-up.

Si/ce71v, 1 / //J/)'

JJ.....~IJ~JL Wm. C. Walbridge -~

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• shall be used to insulate redundant.cable trays

• 1. a)- Kaowool Blanket, Needled, 6# per cubic foot, 24" or 48 wide, 1 thick, standard length.*

11 11 11 b) High performance filamer:it tape, 1 wide, such as that manufactured by 3M Company, St.

• • . *Paul, Minnesota, tape number 898, or its equivalent.

. . c) Regular carbon steel banding material, 3/4 11 wide, 0.015 11 .thtck, waxed .

. .*_. dr. Mastic coating for fire protection applications such as Flamemastic 77, manufactured by

_;.' ~- ...~:*Flamemaster Corporation, Sun Valley, California, or its equivalent_.

.. 2. *For cable trays with no lid and not completely fullj Kaowool blanket shall be cut to the.

. *same width as the cable tray and Ta id on top of the cables 'bo bring the level of/t;he .

Kaowool to the same height as tfle top of the tray. *.For cab],e trays wfth*.Tids .Qr**t.:t.fays tha.t are completely full, no Kaowool filler.blanket ts* required.. **

3. For the interior wrap, the Kaowool blanket shall be cut to a length suffident to wrap completely around the perimeter of the cable tray, plus provide an overlap of blanket of not less than 311 for 18 11 wide tray and not 1ess than -1.sm*_ for 611 wide tray. (.P.l ease see attached drawing. -~ .. -

-4. the interior wrap of blanket sh~ll be held in place using 111 wide filament tape. The tape shall be spaced not less than 4 11 from the ends of each blanket and not more than 14"

• apart froin each other. * .*

5. The next adjacent interior wrap of blanket sha_ll be. cut_;to completely wrap around the

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• perimeter of. the cab 1e tray wi tli enough excess* to provide an overlap of not less than 311 ** The adjacent blankets shall be placed tightly together to prevent any gaps in the

. butt joints between each blanket. * * *:<*>>;.

6.

• For the exterior blanket wrap, cut blanket to sufficient lengtlh to wr~p completely around the perimeter of the interior wrap with sufficient exce~s tc:Lprovtde ari overlap of not less

• than 311

• The blankets to be i.nstalled on the exterior layer _shall be cut if heeded,

• and properly located.to insure that the butt joints on the exterior layer of blanket are not within 12 11 of any butt joint_on the interior blanket wrap.

7. The exterior blanket shal.l be held in place using* regular-carbon steel banding .

material as specified. The bands. shall be:. placed noL.less than 411 from any butt joint on the exterior blanket, nor more than.l4 11 .apar'f:'.ffofu,ach other. The tension on the

banding material shall _be sufficient to hold the olanket snugly in place, ,but not to* *.

cause any significant cutting or damage to the bl~nket:materia]. * *. * *

.* 8 *. Along ttie lenght of the cable tray in areas where support members or adjofoing cable trays or conduit come in contact with the protected tray, such support or tray shall be wrapped using the same techniques to a distance not l_ess *than. 6 11 from the protected cable tray. * * * *

• In areas such as floors, walls, ceilings, *where the blanket :wrap ends, fire. protection seals shall be installed, using mastic coatings as specified. The sealant shall be tfowel or spr~yed completely around the wrapped cable 'tray at the floor, walls, or ceiling.

The seals shall be not less than 1/4 11 thick and extend-not less than 8 11 onto the Kaowool wrap, nor less than 8 11 onto the* floor, wall, or cei.ling.