The first step in any occurrence is emergency classification. Emergency classification is divided into four categories. Emergency Action Levels (EAL), based on indications available in the control room and correlated to the emergency classifications, are provided to the operator. Some EALs are keyed to the safety functions used in Emergency Operating Procedures.
The four emergency classifications including appropriate licensee and state/county government agency emergency response actions are described in the following sections:
Notification of Unusual Event
This classification applies to unusual events that 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.
In these situations, time is available to take precautionary and constructive steps to prevent a more serious event and/or to mitigate any consequences that may occur. This event status places the plant in a readiness position for augmentation of onshift resources and/or possible cessation of routine activities. Appropriate notifications to the Nuclear Regulatory Commission (NRC), state, and county authorities are made.
This classification consists of events that 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 levels. Declaration of an Alert triggers prompt initial and followup notification to offsite authorities. Onsite and offsite emergency centers are activated.
Site Area Emergency
A Site Area Emergency consists of events that 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 PAG exposure levels except near the site boundary. Consideration of appropriate protective actions, based on actual or projected data, is warranted. Assembly and accountability of personnel onsite is mandatory for a Site Area Emergency. Onsite evacuation is initiated if indicated to be necessary by actual or projected doses.
A General Emergency consists of events that 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 PAG exposure levels offsite for more than the immediate site area. There is prompt notification of NRC and appropriate state and county authorities of the General Emergency status.