"R" in the numeric designation signifies that the 1997 standard was reaffirmed (recertified) as an American National Standard in 2003, 2012, and 2017. No changes can be made to a standard during reaffirmation.
This standard is applicable to all operations involving fissionable materials in which inadvertent criticality can occur and cause personnel to receive unacceptable exposure to radiation. This standard is not applicable to detection of criticality events where no excessive exposure to personnel is credible, nor to nuclear reactors or critical experiments. This standard does not include details of administrative actions or of emergency response actions that occur after alarm activation.