Document: NUREG-0800
Document ID: 5cd0267e-b1ef-4ddb-8204-aac45ea7ac13
Document Type: srp
Title: 2.
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070301.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.5.1.4.5
CFR Part: 
CFR Title: 

Content:
15 these parameters should serve as basic input to the review and evaluation of the structural design procedures. 3. The acceptance criteria for the procedures used to transform the tornado parameters into effective loadings on structures are as follows: a. For transforming the tornado wind velocity into an effective pressure applied to structures, the criteria delineated in either the American Society of Civil 16 Engineers (ASCE) Paper No. 3269, "Wind Forces on Structures," (Ref. 2), or in 17 ANSI A58.1, "Building Code Requirements for Minimum Design Loads in Buildings and Other Structures" (Ref. 3) are, in general, acceptable. In particular, the following shall apply: (i) The maximum velocity pressure, p, should be based upon the maximum tornado velocity, V, using the following formula: p = 4.73 x 10 V kPa, in which V is in km/h. -5 2 (p = 0.00256 V psf, in which V is in mph). 2 18 (ii) The velocity pressure should be assumed constant with height. (iii) The maximum velocity pressure, p, applies at the radius of the tornado funnel at which the maximum velocity occurs. The tangential velocity varies with the radial distance from the center of the tornado core. The variation may be considered in accordance with that described in the paper, "Tornado Resistant Design of Nuclear Power Plants." (Ref. 4).19 (iv) For calculating velocity pressures on external surfaces of structures, on external portions thereof, and on internal surfaces where there are openings in the structure, appropriate shape coefficients shall be used in accordance with ASCE Paper No. 3269 (Ref. 2). Gust factors may be 20 taken as unity. DRAFT Rev. 3 - April 1996 3.3.2-4 b. If venting of a structure is adopted as a design measure to permit transforming the tornado-generated differential pressure into an effective reduced pressure, the acceptance criteria are established on a case-by-case basis, upon request, by the Auxiliary Systems Branch (ASB)SPLB.21 c. The acceptance criteria for transforming the