Events that occur on site that could give rise to increasingly severe effects with exposure to individuals off site.
Category 2
Facilities, such as some types of research reactors.
On-site events could expose individuals offsite to unacceptable levels of radiation that require urgent protective action.
Category 3
Facilities, such as industrial irradiation facilities.
On-site events could expose individuals on-site to unacceptable levels of radiation that require urgent protective action.
Category 4
Activities that could result in a nuclear or radiological emergency that would require urgent protective action in locations other than those discussed above.
Includes both authorized and non-authorized activities as well as the transportation of mobile dangerous sources.
Represents the minimum level of threat.
Category 5
Activities that do not involve ionizing radiation but products of these activities are easily contaminated.
This contamination must be from Category 1 or 2 events.
