Any emergency at the Susquehanna plant would fall into one of the following four categories, established by the U.S. Nuclear Regulatory Commission.

Notification of Unusual Event

Events are in process or have occurred which indicate a potential degradation of the level of safety of the plant or indicate a security threat to facility protection has been initiated. No releases of radioactive material requiring offsite response or monitoring are expected unless further degradation of safety systems occurs.

Alert

Events are in process or have occurred that involve an actual or potential substantial degradation of the level of safety of the plant or a security event that involves probable life-threatening risk to site personnel or damage to site equipment because of hostile action. Any releases are expected to be limited to small fractions of the U.S. Environmental Protection Agency Protective Action Guideline exposure levels.

Site Area Emergency

Events are in process or have occurred that involve actual or likely major failures of plant functions needed to protect the public, or hostile action that results in intentional damage or malicious acts toward site personnel or equipment that could lead to the likely failure of, or that prevent effective access to equipment needed to protect the public. Any radioactive releases are not expected to result in exposure levels that exceed EPA Protective Action Guideline exposure levels beyond the site boundary.

General Emergency

Events are in process or have occurred that involve actual or imminent substantial core degradation or melting with potential for loss of containment integrity or hostile action that results in an actual loss of physical control of the facility. Radioactive releases can be reasonably expected to exceed EPA Protective Action Guideline exposure levels offsite for more than the immediate site area.