| International Nuclear Events Scale |
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Information AboutInternational Nuclear Events Scale |
| CATEGORIES ABOUT INTERNATIONAL NUCLEAR EVENT SCALE | |
| nuclear accidents | |
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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 DETAILS Level 7 is characterized by large off-site impact, widespread health and environmental effects. Example: Chernobyl Accident (former Soviet Union ) - 1986 . Level 6 : significant off-site release, likely to require full implementation of planned countermeasures. Example: Mayak (former Soviet Union)- 1957 . Level 5 : limited off-site release, likely to require partial implementation of planned countermeasures. Examples: Windscale Fire ( United Kingdom ) - 1957, Three Mile Island ( United States ) - 1979 . ''The Levels 5-7 are related to severe damage of the reactor core and the radiological barriers.'' Level 4 is related to significant damage of the reactor core / radiological barriers and/or a fatal exposure of a worker (or more), but the off-site impact is minor, resulting in public exposure of the order of the prescribed limits. Examples: Windscale (United Kingdom) - 1973 , Saint-Laurent ( France ) - 1980 , Buenos Aires ( Argentina ) - 1983 . Level 3 is characterized by very small off-site impact, although related to severe spread of contamination on-site / acute health effects to a worker (or more). It is a "near accident" event, when no safety layers are remaining. Example: Vandellos ( Spain ) - 1989 , THORP Plant Sellafield (United Kingdom) - 2005. Level 2 is an incident with no off-site impact, related to significant spread of contamination on-site / overexposure of a worker. Level 1 is an anomaly beyond the authorized operating regime. Level 0 is a "below-scale event" of no safety significance. There are also events of no safety relevance, characterized as "out of scale". EXTERNAL LINKS
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