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The 'International Nuclear Event Scale' (INES) was introduced by the International Atomic Energy Agency (IAEA) in order to enable prompt communication of safety significance information in case of nuclear accidents. A number of criteria and indicators are defined to assure coherent reporting of nuclear events by different official authorities. There are 8 levels on the INES scale:

'7'
Major accident
(maximum credible accident)
'6'
Serious accident
'5'
Accident with off-site risk
'4'
Accident without off-site risk
'3'
Serious incident
'2'
Incident
'1'
Anomaly
'0'
Deviation, no safety relevance

Contents

Details

Level 7

Level 6

Level 5

Level 4

Level 3

Level 2

Level 1

Level 0

See also

References

External links

Details

The level on the scale is determined by the highest of three scores: Off site effects, on site effects, and Defence in depth degradation.

Level 7

A large off-site impact, widespread health and environmental effects. Example: Chernobyl disaster (former Soviet Union) in the Ukraine - 1986. An example of a non nuclear accident which is about the same in magnitude would be the Bhopal disaster where thousands of deaths occurred off site.

Level 6

Significant off-site release, likely to require full implementation of planned countermeasures. Example: Mayak accident (former Soviet Union) - 1957.

Level 5

Limited off-site release, likely to require partial implementation of planned countermeasures. Example: Windscale fire (United Kingdom)- 1957
''or''
Severe damage to a reactor core/radiological barriers.
Example: Three Mile Island accident (United States) - 1979.

Level 4

Minor off-site impact resulting in public exposure of the order of the prescribed limits.
''or''
Significant damage to a reactor core/radiological barriers or the fatal exposure of a worker.
Examples:

★ Sellafield (United Kingdom) - 5 incidents 1955 to 1979^[1]

★ Saint-Laurent Nuclear Power Plant (France) - 1980

★ Buenos Aires (Argentina) - 1983

★ Tokaimura nuclear accident (Japan) - 1999.

Level 3

A very small off-site impact, public exposure at levels below the prescribed limits.
''or''
Severe spread of contamination on-site and/or acute health effects to a worker(s).
''or''
It is a "near accident" event, when no safety layers are remaining.
Examples: THORP plant Sellafield (United Kingdom) - 2005.

Level 2

This is an incident with no off-site impact, a significant spread of contamination on-site may have occurred.
''or''
Overexposure of a worker.
''or''
Incidents with significant failures in safety provisions.
Examples: The Forsmark Nuclear Power Plant (Sweden) - July 2006 incident.

Level 1

This is an anomaly beyond the authorized operating regime.

Level 0

This is a "below-scale event" of no safety significance.
There are also events of no safety relevance, characterized as "out of scale".

See also

★ Chernobyl disaster

★ Chernobyl disaster effects

★ Fuel element failure

★ List of civilian nuclear accidents

★ List of military nuclear accidents

★ List of nuclear reactors

★ Loss of coolant accident

★ Nuclear and radiation accidents

★ Radioactive contamination

★ Nuclear meltdown

★ Nuclear power

★ Nuclear safety

★ Radioactive contamination

★ Radioactive waste

★ Three Mile Island accident

★ United States military nuclear incident terminology

★ Windscale fire

References

1. Classification of events with an off-site radiological impact at the Sellafield site between 1950 and 2000, using the International Nuclear Event Scale, G A M Webb ''et al.'', , , Journal of Radiological Protection,

External links

★ International Nuclear Event Scale, IAEA

★ International Nuclear Event Scale, User's Manual, IAEA, 2001