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:
ications; 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 capability to perform their safety function. Hurricane missiles (i.e., objects moving under the action of aerodynamic forces induced by the hurricane wind) are among the most extreme effects of credible natural phenomena that can occur at nuclear power plant sites subject to hurricanes. To ensure the safety of nuclear power plants in the event of a hurricane strike, NRC regulations require that nuclear power plant designs consider the impact of hurricane-generated missiles, in addition to the direct action of the hurricane wind. Hurricanes are capable of generating missiles from objects lying within the path of the hurricane wind and from the debris of nearby damaged structures. The two basic approaches used to characterize hurricane-generated missiles are (1) a standard spectrum of hurricane missiles, and (2) a site-specific probabilistic assessment of the hurricane hazard. No definitive guidance has been developed for use in characterizing site-dependent hurricane-generated missiles by hazard probability methods. Damage to safety-related structures by hurricane or other wind-generated missiles implies that a sequence of random events has occurred. That event sequence typically includes a wind-based occurrence in the plant vicinity in excess of 34 m/s (75 mph)1, existence and availability of missiles in the area, injection of missiles into the wind field, suspension and flight of those missiles, impact of the missiles on safety-related structures, and resulting damage to critical equipment. Given defense-in-depth considerations, the uncertainties in these events preclude the use of a probabilistic assessment as the sole basis for assessing how well the plant is protected against hurricane missile damage. Protection from a spectrum of missiles (ranging from a massive