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The INES Scale is a worldwide tool for communicatin to the public in a consistentwa the safet sinificance of nuclear and radioloical events.Just like information on earthquakes or temperature would be difficult to understand

without the Richter or Celsius scales, the INES Scale explains the sinificance of

events from a rane of activities, includin industrial and medical use of radiation

sources, operations at nuclear facilities and transport of radioactive material.

Events are classified on the scale at seven levels: Levels 13 are called "incidents"and Levels 47 "accidents". The scale is desined so that the severit of an event is

about ten times reater for each increase in level on the scale. Events without safet

sinificance are called deviations and are classified Below Scale / Level 0.

INESThe inTernaTional nuclear and radiological evenT scale

OECDNuclear Ener Aenc

1

2

6

5

4

3

7

Below Scale / Level 0

N O S A F E T Y S I G N I F I C A N C E

ANOMALY

INCIDENT

SERIOUS INCIDENT

ACCIDENT WITH

LOCAL CONSEQUENCES

ACCIDENT WITH

WIDER CONSEQUENCES

SERIOUS ACCIDENT

MAJOR

ACCIDENT

A

C

C

ID

E

N

T

I

NC

ID

E

N

T

For more information: www-w..

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INES classifies nuclear and radioloical

accidents and incidents b considerin three

areas of impact:

People and the Environment considers the

radiation doses to people close to the location of

the event and the widespread, unplanned release

of radioactive material from an installation.

Radiological Barriers and Control covers

events without an direct impact on people or

the environment and onl applies inside major

facilities. It covers unplanned hih radiation levels

and spread of sinificant quantities of radioactive

materials confined within the installation.

Defence-in-Depth also covers events without

an direct impact on people or the environ-

ment, but for which the rane of measures put

in place to prevent accidents did not function asintended.

Communicatin EventsNuclear and radioloical events are promptl

communicated b the INES Member States,

otherwise a confused understandin of the

event ma occur from media or from public

speculation. In some situations, where not all

the details of the event are known earl on, a

provisional ratin ma be issued. Later, a final

ratin is determined and an differences

explained.

To facilitate international communications for

events attractin wider interest, the IAEA main-

tains a web-based communications network

that allows details of the event to immediatel

be made publicl available.

The two tables that follow show selected

examples of historic events rated usin the

INES scale, ranin from a Level 1 anomal to

a Level 7 major accident; a much wider rane

of examples showin the ratin methodolo

is provided in the INES Manual.

Scope of the ScaleINES applies to an event associated with

the transport, storae and use of radioactive

material and radiation sources, whether or not

the event occurs at a facilit. It covers a wide

spectrum of practices, includin industrial use

ExamplES of EvENtS at NuclEar facIlItIES

People and EnvironmentRadioloical Barriers

and Control Defence-in-Depth

cby, 1986 Widespread health andenvironmental effects. External release of a sinificantfraction of reactor core inventor.

Kytym, r, 1957 Sinificant release ofradioactive material to the environment from explosionof a hih activit waste tank.

W P, uK, 1957 Release of radioactivematerial to the environment followin a fire in a

reactor core.

T M i, usa, 1979 Severe damae to the reactor core.

Tkm, Jp, 1999 Fatal overexposures ofworkers followin a criticalit event at a nuclear facilit.

st lt ex, F,1980 Meltin of one channel offuel in the reactor with no releaseoutside the site.

n xmp b

sf, uK, 2005 Releaseof lare quantit of radioactivematerial, contained within theinstallation.

v, sp, 1989 Near accident caused bfire resultin in loss of safet sstems at the nuclearpower station.

at, at, 2005 Overexposure of a workerat a power reactor exceedin the annual limit.

c, F, 1993 Spreadof contamination to an area not

expected b desin.

Fmk, sw, 2006 Deraded safet functionsfor common cause failure in the emerenc power suppl

sstem at nuclear power plant.

Breach of operatin limits at a nuclear facilit.

Major Accident

Level 7

Serious Accident

Level 6

Accident with

Wider

Consequences

Level 5

Accident with

Local

Consequences

Level 4

Serious Incident

Level 3

Incident

Level 2

Anomal

Level 1

NO SAFETy

SIgNIFICANCE

(Bw s/

l 0)

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such as radioraph, use of radiation sources

in hospitals, activit at nuclear facilities, and

transport of radioactive material.

It also includes the loss or theft of radioactive

sources or packaes and the discover of

orphan sources, such as sources inadvertentl

transferred into the scrap metal trade.

When a device is used for medical purposes

(e.., radiodianosis or radiotherap), INES is

used for the ratin of events resultin in actual

exposure of workers and the public, or involv-

in deradation of the device or deficiencies

in the safet provisions. Currentl, the scale

does not cover the actual or potential con-

sequences for patients exposed as part of a

medical procedure.

The scale is onl intended for use in civil

(non-militar) applications and onl relates

to the safet aspects of an event. INES is

not intended for use in ratin securit-related

events or malicious acts to deliberatel expose

people to radiation.

What the Scale is Not ForIt is not appropriate to use INES to compare

safet performance between facilities,

oranizations or countries. The statisticall small

numbers of events at Level 2 and above and the

differences between countries for reportin more

minor events to the public make it inappropriateto draw international comparisons.

HistorSince 1990 the scale has been applied to

classif events at nuclear power plants, then

extended to enable it to be applied to all

installations associated with the civil nuclear

industr. B 2006, it had been adapted to

meet the rowin need for communication of

the sinificance of all events associated with

the transport, storae and use of radioactive

material and radiation sources.

The IAEA has coordinated its development in

cooperation with the OECD/NEA and with the

support of more than 60 Member States throuh

their officiall desinated INES National Officers.

The current version of the INES manual was

adopted 1 Jul 2008. With this new edition, it

is anticipated that INES will be widel used b

the Member States and become the world-

wide scale for puttin into the properperspective the safet sinificance of nuclear

and radiation events.

INESThe

inTernaTionalnuclearandradiologicalevenTscale

ExamplES of EvENtS INvolvINg radIatIoN SourcES aNd traNSport

People and Environment Defence-in-Depth

7

6

5g, Bz, 1987 Four people died and sixreceived doses of a few g from an abandoned andruptured hihl radioactive Cs-137 source.

4F, Bm, 2006 Severe health effects for aworker at a commercial irradiation facilit as a resultof hih doses of radiation.

3Y, P, 1999 Incident with radioraphsource resultin in severe radiation burns.

ikt, Tky, 1999 Loss of a hihl radioactiveCo-60 source.

2usa, 2005 Overexposure of a radiorapher exceedinthe annual limit for radiation workers.

F, 1995 Failure of access control sstemsat accelerator facilit.

1 Theft of a moisture-densit aue.

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gENEral dEScrIptIoN of INES lEvElS

INES Level People and Environment Radioloical Barriersand Control Defence-in-Depth

Major AccidentLevel 7

Majorreleaseofradioactivematerial

with widespread health and

environmental effects requirin

implementation of planned and

extended countermeasures.

Serious AccidentLevel 6

Significantreleaseofradioactive

material likel to require

implementation of planned

countermeasures.

Accident withWider Consequences

Level 5

Limitedreleaseofradioactivematerial

likel to require implementation of

some planned countermeasures.

Severaldeathsfromradiation.

Severedamagetoreactorcore.

Releaseoflargequantitiesof

radioactive material within an

installation with a hih probabilit of

sinificant public exposure. This

could arise from a major criticalit

accident or fire.

Accident with

ocal ConsequencesLevel 4

Minorreleaseofradioactivematerial

unlikel to result in implementation of

planned countermeasures other thanlocal food controls.

Atleastonedeathfromradiation.

Fuelmeltordamagetofuelresulting

in more than 0.1% release of core

inventor.

Releaseofsignificantquantitiesofradioactive material within an

installation with a hih probabilit of

sinificant public exposure.

Serious IncidentLevel 3

Exposureinexcessoftentimesthe

statutor annual limit for workers.

Non-lethaldeterministichealtheffect

(e.., burns) from radiation.

Exposureratesofmorethan1Sv/hin

an operatin area.

Severecontaminationinanarea

not expected b desin, with a

low probabilit of sinificant public

exposure.

Nearaccidentatanuclearpowerplant

with no safet provisions remainin.

Lostorstolenhighlyradioactive

sealed source.

Misdeliveredhighlyradioactive

sealed source without adequate

procedures in place to handle it.

IncidentLevel 2

Exposureofamemberofthepublic

in excess of 10 mSv.

Exposureofaworkerinexcessofthe

statutor annual limits.

Radiationlevelsinanoperatingarea

of more than 50 mSv/h.

Significantcontaminationwithinthe

facilit into an area not expected b

desin.

Significantfailuresinsafetyprovisions

but with no actual consequences.

Foundhighlyradioactivesealed

orphan source, device or transport

packae with safet provisions intact.

Inadequatepackagingofahighly

radioactive sealed source.

AnomalLevel 1

Overexposureofamemberofthe

public in excess of statutor annual

limits.

Minorproblemswithsafety

components with sinificant

defence-in-depth remainin.

Lowactivitylostorstolenradioactivesource, device or transport packae.

N O S A F E T y S I g N I F I C A N C E ( B w s / l 0 )

Pt ct: c n ey cmm,

gk n Pw Pt, gk, Jp/Ky et Pw c.,

J. M/iaea

INESThe inTernaTional nuclear and radiological evenT scale

International Atomic Ener Aenc

Information Series / Division of Public Information

08-26941 / E