International Nuclear and Radiological Event (INES) Scale

Event

Level

no safety significance

0

anomaly

1

incident

2

serious incident

3

accident with local consequences

4

accident with wider consequences

5

serious accident

6

major accident

7

Parameter

Finding

Level

exposure of member of public

above statutory limits

1

above 10 mSv

2

exposure of worker

above statutory annual limit

2

more than 10 times above statutory annual limit

3

more than 1 Sv per hour in an operating area

3

injury or death

non-lethal (burn, other)

3

>= 1 death

4

several deaths

5

contamination or release within facility

significant into an area not expected by design

2

severe into an area not expected by design, low probability of public exposure

3

significant within facility with high probability of significant public exposure

4

large quantity in installation with high probability of significant public exposure

5

release of radioactive material outside

minor release not requiring planned countermeasure

4

limited release requiring some planned countermeasures

5

significant release with use of countermeasures

6

major release affecting a widespread area and requiring extended countermeasures

7

safety measures and defense in depth

minor problem in safety component with adequate defenses

1

significant failure without actual consequences

2

near accident with no safety provisions remaining

3

loss or stolen

low activity, lost or stolen

1

highly radioactive, found and with safety provisions intact

2

highly radioactive, lost or stolen

3

problems in delivery of highly radioactive source

inadequate packaging

2

misdelivered without adequate radiation procedures for handling

3

reactor fuel or nuclear core

melt or damage with release of less than 0.1% of core inventory

4

severe damage

5