Describing an Incident

Key definitions: incident vs. event

What is the difference between an event and an incident using current US terminology?

    • Event (planned event)
      • Examples: a scheduled nonemergency activity (e.g., sporting event, concert, parade, training exercise, large convention, fair, large gathering, etc.)
    • Incident (unplanned event)
      • Examples: An occurrence or event, natural or manmade that requires a response to protect life or property. Incidents can include major disasters, emergencies, terrorist attacks, terrorist threats, civil unrest, wild land and urban fires, floods, hazardous materials spills, nuclear accidents, aircraft accidents, earthquakes, hurricanes, tornadoes, tropical storms, tsunamis, war-related disasters, public health and medical emergencies, and other occurrences requiring an emergency response.
    • Source: Introduction to the Incident Command System (ICS 100.b), Student Manual, August 2010, (PDF - 8.99 MB). See glossary. This is part of the National Incident Management System (NIMS).

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International Nuclear and Radiological "Event" (Severity) Scale (INES)

  • Developed by International Atomic Energy Agency (IAEA) and partners in 1990 and it has undergone revisions.
  • The diagram below is the current version.
  • Severity scale ranges from 1 (least severe) to 7 (most severe)
  • The severity of an event is about 10 times greater for each increase in level on this scale.
  • Events without safety significance are called "deviations" and are classified as Below Scale/Level 0.
  • See INES information
  • Note nomenclature difference between IAEA and US
    • IAEA nomenclature references "event".
    • US nomenclature references "incident" as in the NIMS.
  • Examples
    • IAEA characterized the March 2011 Fukushima Nuclear Accident in Japan as an INES Level 7 accident
    • IAEA characterized the 1986 Chernobyl nuclear reactor accident in the Ukraine as an INES Level 7 accident.

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Incident's Phases and Timelines

  • The US government interagency has created the following nomenclature to describe the chronological phases of an incident.
  • It is valuable for all agencies to work from the same nomenclature and timeline, as they respond to an incident.
  • Illustration of the current nomenclature for the timeline and its phases.

    Phases of an incident for planning and response
  • Diagram showing the Recovery Continuum timelines and tasks and considerable overlap among recovery tasks during the short term, intermediate term and long term phases of an incident. National Disaster Recovery Framework (PDF - 11 MB) (DHS/FEMA, September 2011) See page 8, Figure 1.
  • 2008 description of phases of an RDD and IND incident has been superseded by the nomenclature above.
  • The EPA PAG Manual Draft for Interim Use, March 2013 also refers to Early, Intermediate, and Late Phases. (See PAG Manual pages 5 and 12 for EPA definitions, which are summarized below.
    • Early phase: lasts hours to days; is the period beginning at the projected (or actual) initiation of a release when immediate decisions for effective use of protective actions are required and must therefore be based primarily on the status of the release and the prognosis for worsening conditions. Little environmental data from actual measurements may be available in the early phase.
    • Intermediate phase: lasts weeks to months; is the period beginning after the source and releases have been brought under control (not necessarily stopped but not growing) and environmental measurements are available for use as a basis for decisions on protective actions. This phase may overlap the early an late phase.
    • Late phase: begins when recovery actions designed to reduce radiation levels in the environment to acceptable levels are begun and ending when all recovery actions have been completed. This phase ay extend from months to years. A PAG level, or dose to avoid, is NOT appropriate for long term recovery.