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:
ced Fujita Scale which was implemented by the National Weather Service in February 2007. The Enhanced Fujita Scale is a revised assessment relating tornado damage to windspeed. The use of the Enhanced Fujita Scale, in addition to the availability of additional tornado data, supported a decrease in design-basis tornado windspeed criteria presented in Revision 1 of RG 1.76. Since design-basis tornado windspeeds were decreased as a result of the analysis performed to update RG 1.76, it was no longer clear that the revised tornado design-basis windspeeds would bound design-basis hurricane windspeeds in all areas of the United States. This prompted an investigation into extreme wind gusts during hurricanes and their relation to design-basis hurricane windspeeds. The NRC commissioned a report (Ref. 7) that considers peak-gust windspeeds and estimates maximum hurricane windspeeds for hurricanes that originate in the Atlantic and make landfall along the Atlantic and Gulf coasts of the contiguous United States. This report does not include locations outside the contiguous 48 states and does not consider hurricanes that originate in the Pacific Ocean. The NRC staff has determined that the design-basis hurricane windspeeds should correspond to the exceedance frequency of 10-7 per year (calculated as a best estimate). This is the same exceedance frequency used to establish the design-basis tornado parameters in Rev. 1 to RG 1.76. This exceedance frequency is also consistent with the Standard Review Plan (NUREG-0800, Ref. 8) Section 2.2.3 (Evaluation of Potential Accidents) criterion for identifying design-basis events involving hazardous materials or activities on site and in the vicinity of a proposed site. Design-Basis Hurricane Windspeeds The analysis in Reference 7 is based 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,”