Document: NRC Regulatory Guide
Document ID: ee571544-47f4-47c8-b15f-c0f8619885f5
Document Type: regulatory_guide
Title: Design-Basis Hurricane and Hurricane Missiles for Nuclear Power Plants + HISTORY - HISTORY 08/2012 – DG-1247 ,Proposed Revision 0
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1004/ML100480890.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.221
CFR Part: 
CFR Title: 

Content:
on the peer-reviewed hurricane simulation model that was used for the development of windspeed maps for Standard ASCE/SEI 7-05 (Ref. 9), “Minimum Design Loads for Buildings and Other Structures,” from the American Society of Civil Engineers (ASCE) and the Structural Engineering Institute (SEI). The model generated peak-gust windspeeds at 3,575 grid points along and inland of the Atlantic and Gulf Coasts of the United States. A stratified sampling approach facilitated a simulation with an effective length of 10 million years that computed windspeeds for each model hurricane at each affected grid point. The range of hurricane parameters in the precomputed wind fields in the model was extended to cover the smaller and more intense hurricanes that are occasionally simulated in the 10-million-year event set. In addition to the computation of a deterministic peak-gust windspeed for each model hurricane, the analysis incorporated a wind field modeling error term. The error term includes the inability of the wind model to capture some asymmetries in the underlying model pressure fields, as well as the inability of the model to capture small-scale features such as extreme convective gusts. The inclusion of this error term resulted in an effective maximum peak gust in the range of 1.7 to 1.8 times the mean windspeed. DG-1247, Page 4 The resulting windspeeds are nominal 3-second peak-gust values at a height of 10 meters (m) (33 feet (ft)) in flat open terrain, which is consistent with the definition of design windspeeds in the ASCE/SEI design standard. Figures 1 through 3 provide hurricane windspeed contour maps from Reference 7 that correspond to an exceedance frequency of 10-7 per year. Hurricane-Generated Missiles In accordance with 10 CFR 50.34, “Contents of Applications; Technical Information,” GDC 2, and GDC 4, structures, systems, and components that are important to safety must be designed to withstand the effects of natural phenomena without losing the