The International Nuclear and Radiological Event Scale (INES)

The International Nuclear and Radiological Event Scale (INES) is a tool for promptly communicating to the public in consistent terms the safety significance of nuclear and radiological incidents and accidents. The scale was designed by an international group of experts first convened jointly in 1989 by the International Atomic Energy Agency (IAEA) and the Nuclear Energy Agency of the Organization for Economic Co-operation and Development (OECD/NEA).

Initially the scale was applied to classify events at nuclear power plants. More recently, it has been extended and adapted further to meet the growing need for communication of the significance of all events associated with the transport, storage and use of radioactive material and radiation sources.

INES user's manual

The INES User’s Manual 2008 Edition supersedes the 2001 edition and is applicable to the assessment of all relevant events in order to determine the nuclear and radiological significance to the public.

The primary purpose of the INES Scale is to facilitate communication and understanding between the technical community, the media and the public on the safety significance of events. It covers a wide spectrum of practices, including industrial use such as radiography, use of radiation sources in hospitals, operations at nuclear facilities, and transport of radioactive material. Events are classified on the scale at seven levels: Levels 4–7 are termed 'accidents' and Levels 1–3 'incidents'. Events without safety significance are termed 'deviations' and are classified below scale at Level 0.

The current version of the INES User’s Manual (2008 Edition) is designed to assist those who are required to rate the safety significance of events using the scale. In addition to consolidating assessment methodology for nuclear, radiation sources and nuclear material transport events, the INES assessment methodology has undergone an overhaul from previous editions and is now more user-friendly. The individual chapters contain assessment tools with autonomous methodologies that do not require knowledge of other chapters. Practical examples of event assessments placed at the end of each chapter have been expanded from previous versions. The definitions and assessment criteria have been improved to provide more clarity.

With this edition, it is anticipated that INES will become the worldwide scale for putting into proper perspective the safety significance of any event associated with the transport, storage and use of radioactive material and radiation sources, whether or not the event occurs at a facility.

In October 2014, the IAEA published supplementary guidance The Use of the International Nuclear and Radiological Event Scale (INES) for Event Communication (PDF 2.32 mb). It provides guidelines and good practices for setting up a national framework on the effective use of the INES Scale for event communication. The objective of the publication is to assist governments and other organisations involved to establish or improve the national framework to effectively use INES as an integral part of the communication strategy. The included examples of good practices illustrate the breadth of approaches that can be adopted to meet the fundamental goal of INES – to effectively and consistently communicate the safety significance of an event.

The IAEA maintains a website of events. The events that occurred over the previous six months may be viewed at the IAEA website. ARPANSA provides information to the IAEA on INES reportable events which occur in Australian jurisdictions.