Notification of Unusual Event

• Events are occurring, or have already occurred, that threaten the level of safety at the site. It is unclear whether radioactive material has been or is being released. Workers are at risk.
  
  

Alert

• Events may result in a substantial degradation of the level of safety at the site. A release of radioactive material is expected to be limited.
  
  

Site Area Emergency

• Events will likely result in major failures of plant functions, which are needed for the protection of the public. Radioactive releases are expected to stay within the Environmental Protection Agency (EPA) "protective action guides."
  
  

General Emergency

• Actual or imminent substantial core damage or melting of reactor fuel and potential loss of containment integrity. Radioactive releases expected to exceed the protective action guides.