Accident ClassificationsThe US NUCLEAR Regulatory Commission has developed four action levels to address how agencies should respond to NPPs incidents that could lead to serious consequences. The actions taken by state and local agencies in response to a notification of an incident are GRADUATED from a notification to be aware of a situation to full emergency response actions. This graduated response ensures that emergency response preparations can be taken in advance of a severe accident if a minor situation worsens. The four accident classifications are: Notification of UNUSUAL Event, Alert, SITE Area Emergency, and General Emergency, and are described below.Notification of Unusual EventThis classification is used to describe events that indicate a potential degradation of safety at a NPP. Offsite response or MONITORING is not expected unless further degradation of safety systems occurs. Its purpose is to assure that the first steps in response preparations have been carried out and to bring state and local response organizations to a state of readiness. During this classification authorities provide fire or security assistance as requested and standby for additional information.AlertEvents are in process or have occurred that indicate an actual or potential substantial degradation of safety at a plant. Any release of radioactive material is expected to be limited to small fractions of the EPA Protective Action Guideline (PAG) Exposure Levels. It assures that emergency personnel are readily available to respond if the situation becomes more serious or to perform confirmatory radiation monitoring if required and provide state and local authorities current status information. In addition to the assistance requested for an unusual event, authorities augment emergency response resources, provide confirmatory offsite radiation monitoring or ingestionPage 71Suggested Citation:"5 Protective Measures." National Research Council. 2004. Distribution and Administration of Potassium Iodide in the Event of a Nuclear Incident. Washington, DC: The National Academies Press. doi: 10.17226/10868.×Add a note to your bookmarkpathway dose projections