|Level||Definition||People and environment||Radiological barriers & control||Defence in depth||Example|
|7||Major accident||Major release of radio active material with widespread health and environmental effects requiring implementation of planned and extended countermeasures||Chernobyl, Ukraine, 1986|
|6||Serious accident||Significant release of radioactive material likely to require implementation of planned countermeasures.||Kyshtym, Russia, 1957|
|5||Accident with wider consequences||Limited release of radioactive material likely to require implementation of|
some planned countermeasures • Several deaths from radiation
|• Severe damage to reactor core.|
• Release of large quantities of radioactive material within an installation
with a high probability of
significant public exposure. This
could arise from a major criticality accident or fire
|Windscale, UK, 1957; Three Mile Island, 1979|
|4||Accident with local consequences||• Minor release of radioactive material unlikely to result in implementation of planned countermeasures other than|
local food controls.
• At least one death from radiation.
|• Fuel melt or damage to fuel resulting in more than 0.1% release of core inventory.|
• Release of significant quantities of radioactive
material within an installation with a high probability of significant
|FUKUSHIMA 1, 2011|
|3||Serious incident||• Exposure in excess of ten times the statutory annual limit for workers.|
• Non-lethal deterministic health effect (e.g., burns) from radiation.
|• Exposure rates of more than 1 Sv/h in an operating area.|
• Severe contamination in an area not expected by design, with a
of significant public exposure.
|• Near accident at a nuclear power plant|
with no safety provisions remaining.
• Lost or stolen highly radioactive sealed source.
• Misdelivered highly radioactive sealed source without adequate procedures in place to handle it.
|Sellafield, UK, 2005|
|2||Incident||• Exposure of a member of the public|
in excess of 10 mSv.
• Exposure of a worker in excess of the
statutory annual limits
|• Radiation levels in an operating area|
of more than 50 mSv/h.
• Significant contamination within the
facility into an area not expected by
|• Significant failures in safety provisions|
but with no actual consequences.
• Found highly radioactive sealed
orphan source, device or transport
package with safety provisions intact.
• Inadequate packaging of a highly
radioactive sealed source.
|Atucha, Argentina, 2005|
|1||Anomaly||• Overexposure of a member of the|
public in excess of statutory annual
• Minor problems with safety
components with significant
• Low activity lost or stolen radioactive
source, device or transport package