Radiological Information & Glossary - NRC Incident Classification / Notification

The Nuclear Regulatory Commission's (NRC) classification of four levels of radiological emergencies: Notification of Unusual Event, Alert, Site Area Emergency, and General Emergency.

The response taken by Westchester, Rockland, Orange and Putnam counties and New York State will depend on the severity of the incident described by the NRC’s pre-established classifications. Because these four classifications are based on specific plant conditions and measurements, they provide a clear indication of the seriousness of the event.

Unusual events are in progress or have occurred which indicate a potential degradation of the level of safety of the plant. No releases of radioactive material requiring offsite response or monitoring are expected unless further degradation of safety systems occur.
Events are in progress or have occurred which involve an actual or potential substantial degradation of the level of safety of the plant. Any releases are expected to be limited to small fractions of the Environmental Protection Agency (EPA) Protective Action Guideline (PAG) exposure level.
Events are in progress or have occurred which involve actual or likely major failures of plant functions needed for protection of the public. Any releases are not expected to exceed EPA Protective Action Guideline exposure levels except near the site boundary.
Events are in progress or have occurred which involve actual or imminent substantial core degradation or melting with potential for loss of containment integrity. Releases can be reasonably expected to exceed EPA Protective Action Guideline exposures offsite for more than the immediate site area.