"R" in the numeric designation signifies that the 2011 standard was reaffirmed (recertified) as an American National Standard in 2016. No changes can be made to a standard during reaffirmation.
This standard establishes guidelines to estimate the frequency of occurrence and the magnitude of parameters associated with rare meteorological events such as tornadoes, hurricanes, and extreme straight line winds at nuclear facility sites within the continental United States. The parameters addressed include the following: maximum wind speed (e.g., translational, rotational, and total), maximum atmospheric pressure drop, and design basis missile characteristics. Recommended values of these parameters are provided. This standard does not address the forces on structures that result from these physical phenomena.