International Nuclear Event Scale

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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
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

[edit] 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.

[edit] Level 7

A large off-site impact with widespread health and environmental effects. So far, the Chernobyl disaster is the only accident to reach level 7. An example of a non nuclear accident of roughly the same magnitude would be the Bhopal disaster which resulted in thousands of off-site deaths.

[edit] Level 6

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

[edit] 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.

[edit] 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:

[edit] 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 one or more workers.

or

It is a "near accident" event, when no safety layers are remaining.

Examples:

[edit] 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: -Ascó (Catalonia, Spain) April 2008

-The Forsmark Nuclear Power Plant (Sweden) - July 2006 incident.

[edit] Level 1

This is an anomaly beyond the authorized operating regime.

[edit] 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".

[edit] See also

[edit] References

  1. ^ G A M Webb et al. (March 2006). "Classification of events with an off-site radiological impact at the Sellafield site between 1950 and 2000, using the International Nuclear Event Scale". Journal of Radiological Protection 26. 

[edit] External links