Document: NRC Regulatory Guide
Document ID: 4f130c35-25dc-4950-b437-3801efdab5f6
Document Type: regulatory_guide
Title: Protection Against Extreme Wind Events and Missiles for Nuclear Power Plants (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1435/ML14356A107.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.117
CFR Part: 
CFR Title: 

Content:
nd licensees should consider subsequently-occurring low probability events (e.g. loss-of-coolant accident followed by a design bases tornado). For this reason, equipment used to provide long term core cooling following a loss-of-coolant accident should be protected against extreme wind events. Harmonization with International Standards The NRC staff reviewed guidance from the International Atomic Energy Agency (IAEA) and did not identify any standards that provided useful guidance to NRC staff, applicants, or licensees. C. STAFF REGULATORY GUIDANCE Structures, systems, and components important to safety that should be protected from both the direct and indirect effects of extreme wind events (tornado or hurricane) are: 1. those necessary to ensure the integrity of the reactor coolant pressure boundary, 2. those necessary to ensure the capability to shut down the reactor and maintain it in a safe shutdown condition (this includes both hot standby and cold shutdown capability), and DG-1313, Page 4 3. those whose failure could lead to radioactive releases resulting in calculated offsite exposures greater than 25 percent of the guideline exposures of 10 CFR Part 100 using appropriately conservative analytical methods and assumptions. Protection applies both the effects of the extreme wind directly acting on the SSCs, as well as wind effects such as wind-generated missiles. It is the responsibility of applicants and licensees to determine which SSCs perform the above functions and thus are protected. The appendix to this guide lists structures, systems, and components, which together with their foundations and supports, typically should be protected from the effects of a design-basis tornado (see RG 1.76) and design-basis hurricane (RG 1.221), including generated missiles, without loss of capability to perform their safety functions. Those structures, systems, and components that should be protected may be different from the appendix list for designs that differ