ML21294A169
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SSES-FSAR Text Rev. 52 3.3 WIND AND TORNADO LOADINGS 3.3.1 WIND LOADINGS All exposed structures are designed for wind loading.
3.3.1.1 Design Wind Velocity The design wind velocity for all structures is 80 mph at 30 ft above ground for a 100-year recurrence interval. The design wind velocity is based on Figure 5 of Reference 3.3-1.
(References are listed in Subsection 3.3.3.)
The vertical velocity distribution is based on Table 1(a) of Reference 3.3-2. The velocity distribution is tabulated in Table 3.3-1.
A gust factor of 1.1, as given in Reference 3.3-2, is used.
3.3.1.2 Determination of Applied Forces The procedure used to transform the wind velocity into an effective pressure applied to exposed surfaces of structures is as described in Reference 3.3-2 and is summarized as follows:
The dynamic pressure is given by:
q = 0.002558 V2 where, q = Dynamic pressure in psf V = Wind velocity in mph (design wind velocity x gust factor).
The local pressure at any point on the surface of a building is equal to:
q x Cp Where Cp = Pressure coefficient.
The total pressure on a building is equal to:
q x CD
- Where, FSAR Rev 64 3.3-1
SSES-FSAR Text Rev. 52 CD = Shape coefficient.
The Susquehanna SES structures have sloping roofs with a pitch less than 20 degrees. The following are values for Cp and CD. (See Reference 3.3-2, p. 1151 and Figure 7.)
Cp for windward wall = 0.8 (pressure)
Cp for leeward wall = -0.5 (suction)
Cp for windward slope = 0 Cp for leeward slope = -0.6 (suction)
CD = 1.3 (pressure).
Wind loads on structures are tabulated in Table 3.3-1.
Exposed tanks are designed to resist a minimum wind load of 30 psf on the vertical projection, based on Reference 3.3-3. For cylindrical tanks, wind is considered acting on six-tenths of the vertical projection. No increases in allowable working stresses are permitted for these structures for loading conditions involving wind.
3.3.2 TORNADO LOADINGS Table 3.3-2 lists the systems that are protected against tornadoes and the enclosures which provide this protection. This table is based on NRC Regulatory Guide 1.117 (Reference 3.3-4).
3.3.2.1 Applicable Design Parameters The following design parameters are used for the design of tornado-resistant structures and are based on Reference 3.3-5:
a) Dynamic Wind Loading Tangential speed: 300 mph Translational speed: 60 mph These speeds apply to all tornado-resistant structures except the Diesel Generator 'E' Building where a tangential speed of 290 mph and a translational speed of 70 mph are used.
b) Pressure Differential Between the Inside and Outside of a Building A pressure drop of 3 psi is applied. A rate of 1 psi per second is used for all tornado-resistant structures except the Diesel Generator 'E' building where a rate of 2 psi per second is used.
FSAR Rev 64 3.3-2
SSES-FSAR Text Rev. 52 c) Tornado-Generated Missiles These are discussed in Subsection 3.5.1.4.
3.3.2.2 Determination of Forces on Structures The following procedures are used to transform the tornado loadings into effective loads on structures:
a) Dynamic Wind Loading A procedure the same as the one utilized to transform the wind velocity into an effective pressure, as described in Subsection 3.3.1.2, is used with the following exceptions:
- 1) Velocity and velocity pressure are assumed not to vary with height.
- 2) The gust factor is taken as unity.
As shown in Figure 5 of Reference 3.3-5, and as explained therein, the equivalent uniform tornado wind velocity on the building due to a tangential component of 300 mph and a translational component of 60 mph is 220 mph. The pressure loads are calculated on the basis of a uniform 300 mph wind velocity for all tornado-resistant structures except the Diesel Generator 'E' Building where they are calculated using a 360 mph wind velocity. The pressure loads are as follows:
For All Tornado-Resistant Structures For the Except the Diesel Diesel Generator 'E' Bldg. Generator 'E' Bldg.
Windward pressure on walls: 185 psf 266 psf Leeward suction on walls: 115 psf 166 psf Total design pressure: 300 psf 432 psf Suction (uplift) on roof: 140 psf 199 psf "The turbine building is designed to resist the tornado loading assuming 2/3 of the metal siding and the roof deck being blown away. However, all the frames are designed for the full tornado loading. The metal siding and the roof deck of all structures are not designed to resist full tornado loading."
FSAR Rev 64 3.3-3
SSES-FSAR Text Rev. 52 b) Differential Pressure Loading Differential pressure loading is calculated using the following pressure-time function:
The differential pressure is assumed to vary from zero to 3 psi, remain at 3 psi for 2 seconds and then return to zero. A rate of 1 psi per second is used for all tornado-resistant structures except the Diesel Generator 'E' building where a rate of 2 psi per second is used.
Blowout panels are used as necessary on safety-related structures to minimize differential pressure.
c) Tornado-Generated Missiles Tornado-generated missiles used in the design of the tornado-resistant structures are given in Table 3.5-4 except those missiles used in the design of the Diesel Generator 'E' Building which are given in Table 3.5-4a. The barrier design procedures are described in Subsection 3.5.3.
Loadings a), b), and c) are combined in the following manner to obtain the total tornado loading:
(i) W' = Ww (ii) W' = Wp (iii) W' = Wm (iv) W' = Ww+0.5Wp (v) W' = Ww+Wm (vi) W' = Ww+0.5Wp+Wm Where, W' = Total tornado load Ww = Tornado wind load Wp = Tornado differential pressure load, and Wm = Tornado missile load 3.3.2.3 Effect of Failure of Structures or Components Not Designed for Tornado Loads Structures not designed for tornado loads are checked to ensure that during a tornado they will not generate missiles that have more severe effects than those listed in Table 3.5-4. The modes of failure of these structures are analyzed to verify that they will not collapse on safety related structures.
FSAR Rev 64 3.3-4
SSES-FSAR Text Rev. 52 3.3.2.4 Safety-Related Equipment Not Protected By Reinforced Concrete SECURITY-RELATED INFORMATION.
TEXT WITHHELD UNDER 10 CFR 2.390 FSAR Rev 64 3.3-5
SSES-FSAR Text Rev. 52 SECURITY-RELATED INFORMATION.
TEXT WITHHELD UNDER 10 CFR 2.390 3.
3.3 REFERENCES
3.3-1. H. C. S. Thom, "New Distributions of Extreme Winds in the United States,"
Journal of the Structural Division, ASCE (July 1968), p. 1787.
3.3-2. "Wind Forces on Structures", ASCE Paper No. 3269, Transactions, Volume 126, Part II (1961), p. 1124.
3.3-3. "Steel Tanks, Standpipes, Reservoir, and Elevated Tanks for Water Storage, AWWA Standard, D100-73.
3.3-4. "Tornado Design Classification, US NRC Regulatory Guide 1.117, (June 1976).
3.3-5. J. A. Dunlap and Karl Wiedner, "Nuclear Power Plant Tornado Design Considerations, Journal of the Power Division, ASCE, (March 1971).
3.3-6 "Design Basis Tornado For Nuclear Power Plants," US NRC Regulatory Guide 1.76, (April 1974).
FSAR Rev 64 3.3-6
T-ABL E_J!,.3-1 WIND LOADS ON STHUCTU~ES Total P.nof t: :l 11 L0'1d 0-'?'siqn Lni1d B,1 si<:
Heiqht Vind nvnamic Win1warJ LcP.ward Zone Velocity Pressure Pressure suction Pressur'-1 Sur; t iori (ft) (mph) q (psfJ 0.8q O. Sq ,
- 31, * (, q 0-50 80 20 16 10 26 l?.
50-150 95 30 24 15 39 HI 150-000 110 q0 12 20 52 2'4 400-700 120 ll 5 3b 23 5 '1 27 Rev. 3 5, O7 / 8 4
SSES-FSAR TABLE 3.3-2 TORNADO WIND PROTECTED SYSTEMS AND TORNADO RESISTANT ENCLOSURES Page 1 of 2 Protected System Tornado Resistant Enclosure
- 1. Reactor coolant pressure Reactor Building boundary
- 2. Reactor core and reactor Reactor Building vessel internals
- 3. Systems or portions of systems required for a) Reactor shutdown Reactor Building b) Residual Heat Reaetor Building Removal c) Cooling the spent Reactor Building fuel storage pool
.d) Makeup water for Reactor Building primary system e) Systems necessary to ESSW Pumphouse and Reactor support service Building water, cooling water source, and component cooling
- 4. Reactivity control Reactor Building and Control systems Building
- 5. Control room Control Building
- 6. Monitoring, actuating, Reactor Building and and operating systems Control Building important to safety
- 7. Electric and mechanical Reactor Building, Diesel devices and circuitry Generator Buildings, and ESSW I between the process Pumphouse sensors and the input terminals of the actuator systems involved i:n_. generating signals that initiate protective action Rev. 40, 09/88
SSES-FSAR TABLE 3.3-2 (Continued)
Page 2 of 2 Protected System Tornado Resistant Enclosure
- 8. Long-term emergency Reactor Building, Diesel core cooling system GeDerator Buildings, and ESSW Pumphouse
- 9. Class lE electric All Seismic Category I systerns structures Rev. 40, 09/88