ML20078R786

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Structural Steel Analysis:Reactor Bldg,Elevation 283 Ft, General Floor Area,Fire Area 47A
ML20078R786
Person / Time
Site: Limerick Constellation icon.png
Issue date: 11/01/1983
From:
PROFESSIONAL LOSS CONTROL, INC.
To:
Shared Package
ML20078R738 List:
References
NUDOCS 8311150295
Download: ML20078R786 (9)
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}(( IVofessional Loss Control, Inc.

STRUCTURAL STEEL ANALYSIS for LIMERICK GENERATING STATION Unit 1

. Reactor Building El . 283' General Floor Area

. Fire Area 47A i

November 1, 1983 l

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E 7922 West Chester Pike e Upper Darby, Pa. 19082 * (215) 853 1700

LIMERICK GENERATING STATION

1. AREA DESCRIPTION The area under consideration is the general floor area on the 283' eleva-tion of the Unit 1 Reactor Building (Fire Area 47A). The heaviest combusti-ble loading encountered on this elevation is found in the northeast corner.

The area of heaviest combustible loading is bounded by column lines 20 & 23 and J & H (see Attachment A for sketch of area). Bounding walls are of reinforced concrete construction with an average thickness of 3 ft. Total surface, area for heat transfer is 6947 ft (645 2 m2) (see Attachment A for calculation of areas).

2. COMBUSTIBLE LOADING The heaviest concentration of cabling found within this area is located five feet to the west of column line 21.5. The average combustible loading of the cable trays in th*! .rea is 4 lbs/ft2 of tray surface area. There l are no combustible liquids in this area. Enclosed combustibles are not included in the combustible loading.
3. VENTILATION PARAMETERS The area under consideration is open to the remainder of this elevation on its south side, however, there are several rooms at floor level that extend  ;

a height of 12 ft from the floor. This leaves a ventilation opening above these rooms approximately 54' wide by 17' high.

4. CASES EXAMINED A spreading cable fire was assumed to originate in the area of heaviest cable conccntration in order to present the worst case. The fire is assumed to start at a point source and spread horizontally along the cable trays in each direction at a rate of 10 feet per hour. The fire is assumed to extend alcng the north wall and southwest, a distance of 7 feet before the original point source dies 'out after 40 minutes. A maximum surface area of 172 ft2 of cable trays (see Attachment B for list of' cable trays initially burning) will be involved at any one time, which corresponds to a heat output of approximately 3050 kW. This heat output' is assumed constant )

throughout the fire duration. The actual heat output as the fire spreads I out of the area originally involved would be less because concentrations of cabling that would be involved at any one time would be less. '

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5. RESULTS The fire was assumed to last 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> with no action taken by plant per-sonnel to extinguish the fire. The peak gas temperature reached was 731*F- (see Attachment C) which is below the critical temperature for 1

the structural steel. Since the fire was assumed to occur in the area j of heaviest combustible loading, the results are considered to be l

representative for the entire general floor area on the 283' elevation j of the Reactor Building.

The position of cable trays relative to structural steel members were examined throughout the 283' elevation of the Reactor Building in order to assess the potential for localized heating. Cable trays were encoun-tered within 1 foot of type 36WF230 beams in numerous locations. Cable

! trays ICCRA, ICCTA, IMIAB, and 1ACYA were positioned 12 inches below a 18WF45 beam located northeast of the drywell near column line 20.

Attachment D contains the results of calculations performed to deter-mine the response of the structural members. The exposure time for the localized heating was taken to be 40 minutes which is the time required for a tray to burn to completion. As can be seen from the results, the member types 36WF230 will not reach their critical temperature during the 40 minute exposure period. The member type 18WF45 will exceed its critical temperature well within the exposure period. Appendix D includes a sketch showing the location of the structural member which will fail due to localized heating effects.

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Unit 1 Reactor Building El. 283' Surface Area Calculation Walls North wall (61' x 29') 1769 ft2 South wall (48' x 12') 576 ft2 East wall (44' x 29') 1276 ft2 West wall (46' x 29') 1334 ft2 4955 ft2 Ceiling Area 1 (30' x 60') - (18' x8' stairwell) 1655 ft2 Area 2- (24' x 14') 336 ft2 1992 ft2 Total Surface Area for Heat Tiansfer 6947 ft2(645m2)

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4 ATTACHMENT A ,

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Cable Trays

' The following cable trays are present in the area defined for the source fire and all of the trays are assumed to burn simultaneously.

Surface Cable Tray No. Tray Width (in) Tray Length (ft) Area (ft 2)_

1M1AC01-02 24 15 30 1M1AD01-02 24 15 30 1M1AE01-02 24 15 30 10CVA18 24 15 30 >

101SA73 24 2 4 1BCWA91 24 7 14 1BCWA92 24 5 10 IBCWA80 24 7 14 1BCWA75 24 5 10 172 172 ft_2 _ x 190 kW/m2 = 3050 kW 10.76 ft'/m' Average Combustible Loading per Tray Surface Area = 4.0 lb/ft2 Fire Duration for Free Burning Tray Fires =

4.0 lb/ft2 + 0.1 lb = 40 minutes ft'/ min t

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CASE NUMBER: .1 BUILDING: UNIT'1 REACTOR BUILDING ELEVATION AND AREA DESCRIPTION: 2" NORTHEAST CORNER CASE DESCRIPTION: ONE OPENING SPREADING CADLE FIRE u a *u * *

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  • CEILING / WALL CEILING / WALL Ao' Ho Aw Q THICKNESS hATERIAL (ft) (ft2) (ft) (ft2) (kW) x nun
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'3. 0 CONCRETE 910 17 6947 3050 FIRE IS FUEL CONTROLLED FIRE DURATION GAS TEMPER ATURE (min) (deg.F) 10 220 20 292 30 341 40 383 50 419 60 452

. 70 483 80 511 90 538

-100 563 a 110 507 120 610 130 632 140 ,

653 150 672 160~ 693 170 712 180 731 a

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ATTACHMENT C

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CASE NUMBER: 1 BUILDING:' . UNIT 1 REACTOR DUILDING

-ELEVATION AND. AREA DESCRIPTION: 283' GENERAL FLOOR AREA CASE DESCRIPTION: LOCALIZED HEATING OF MEMBER TYPE 10WF45 EFFECTS OF LOCAL HEATING ON STRUCTURAL GTEEL FIRE TEMPERATURE (deg. F): 1500 WEIGHT OF STEEL MEMBER (lbs./ft): 45 SURFACE OF STEEL MEMBER HEATED (sq.ft./ft): 4.41 TIME STEEL TEMPERATURE

'(min) (deg.F) 5.00 622 10.00 962 15.00 1170 20.00- 1298 25.00 1376 .

30.00 1424 35.00 1453 40.00- 1471 O

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ATTACHMENT D

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CASE NUMBER: 2 BUILDING: UNIT 1 REACTOR BUILDING ELEVATION AND AREA DESCRIPTION: 283' GENERAL FLOOR AREA CASE DESCRIPTION: LOCALIZED HEATING OF MEMBER TYPE 36WF230 EFFECTS OF LOCAL HEATING ON STRUCTURAL STEEL

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FIRE: TEMPERATURE (deg. F): 1500 WEIGHT OF STEEL MEMBER (lbs./ft): 230 SURFACE OF STEEL MEMBER HEATED (sq.ft./ft): 9.84 TIME STEEL TEMPER ATURE (nin) (deg.F) 5.00 310 10.00 511 15.00 678 20.00 817 25.00 932 30.00 1028 35.00 1108 40.00 1174 9

4 ATTACHMENT D

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