Level

Area of impact

Off-site impact

On-site impact

Impact on defence in depth

7

Major Accident

Major release:

 Widespread health and environmental effects

6

Serious Accident

Significant release:

 Likely to require full implementation of planned countermeasures

5

 
Accident with off-site risk

Limited release:

 
Likely to require partial implementation of planned countermeasures

Severe damage to reactor core/ radiological barriers

4

 
Accident without significant off-site risk

Minor release:

 
Public exposure of the order of prescribed limits

Significant damage to reactor core/ radiological barriers

 
Fatal exposure of a member of a worker

3

Serious incident

Very small release:

 Public exposure at a fraction of prescribed limits

Severe spread of contamination

 
Acute health effects to a worker

Near accident

 
No safety layers remaining

2

 
Incident

Significant spread of contamination

 
Overexposure of a worker

Incident with significant failures in safety provisions

1

Anomaly

Anomaly beyond the authorized operating regime

0

Deviation

No safety significance