IAEAInternational Atomic Energy Agency

The International Nuclear The International Nuclear and Radiological Event Scaleand Radiological Event Scale

INESINESDenis FloryDenis Flory

Deputy Director GeneralDeputy Director GeneralDepartment of Nuclear Safety and SecurityDepartment of Nuclear Safety and Security

International Atomic Energy AgencyInternational Atomic Energy Agency

IAEA

What is INES?What is INES?

• International event rating scale with the aim of International event rating scale with the aim of communicating to the public the safety significance of communicating to the public the safety significance of nuclear and radiological eventsnuclear and radiological events

• Provides criteria for rating any event associated with Provides criteria for rating any event associated with the transport, storage and use of radioactive materialthe transport, storage and use of radioactive material

• Jointly developed in 1990 by the IAEA and OECD/NEA Jointly developed in 1990 by the IAEA and OECD/NEA

• INES communication network comprises over 70 INES communication network comprises over 70 Member StatesMember States

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Understanding the INES ScaleUnderstanding the INES Scale

Chernobyl (1986)Chernobyl (1986)

Kyshtym (1957Kyshtym (1957))TMI (1979)TMI (1979)

Tokaimura (1999)Tokaimura (1999)

Vandellos (1989)Vandellos (1989)

Forsmark (2006)Forsmark (2006)

Breach of Breach of operating limitsoperating limits

www-news.iaea.orgwww-news.iaea.org3

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Using the INES Scale: three criteriaUsing the INES Scale: three criteria

1.1. Impact on people and environmentImpact on people and environment

• Activity released or dose received Activity released or dose received

2.2. Impact on radiological barriers and controls (former on-Impact on radiological barriers and controls (former on-site impact) site impact)

• The severity of the event insideThe severity of the event inside the site of a facility and the the site of a facility and the potential harm to the publicpotential harm to the public

3.3. Degradation in “Defence in Depth” Degradation in “Defence in Depth”

• Looking at failures in safety provisions to determine how close Looking at failures in safety provisions to determine how close the event was to causing actual consequencesthe event was to causing actual consequences

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General Description of CriteriaGeneral Description of Criteria

At Level 4/5: fuel At Level 4/5: fuel damage and damage and

radiological barrier radiological barrier damage occursdamage occurs

At Level 6/7: significant At Level 6/7: significant radiological releases radiological releases

occuroccur

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"All safety activities, whether organizational, behavioural or equipment related, are subject to layers of overlapping provisions, so that if a failure should occur it would be compensated for or corrected without causing harm to individuals or the public at large...”

Basic Safety Principles for Nuclear Power Plants (INSAG-3)

• The strategy for defence in depth is twofold: first, to prevent accidents and second, if prevention fails, to limit the potential consequences of accidents and to prevent their evolution to more serious conditions.

Defence in Depth ExplainedDefence in Depth Explained

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Defence in Depth IllustratedDefence in Depth Illustrated

1.1. The fuel matrixThe fuel matrix2.2. The fuel claddingThe fuel cladding3.3. The boundary of the Reactor The boundary of the Reactor

Coolant SystemCoolant System4.4. The Containment SystemThe Containment System5.5. Mitigation of the radiological Mitigation of the radiological

consequences of significant external consequences of significant external releases of radioactive materialsreleases of radioactive materials• Quality AssuranceQuality Assurance• Control systems (alarms)Control systems (alarms)• Safety cultureSafety culture• Accident managementAccident management• Emergency planningEmergency planning

PHYSICAL

PROCEDURAL

Based on INSAG-10: Based on INSAG-10: Defence in Depth in Nuclear SafetyDefence in Depth in Nuclear Safety

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Defence in Depth RatedDefence in Depth Rated

Initiator approach: Initiator approach: • The occurrence that The occurrence that cchallenges hallenges

the safety systems, e.g. reactor the safety systems, e.g. reactor trip, loss of coolant, loss of off-trip, loss of coolant, loss of off-site powersite power

• Power reactor while at power; Power reactor while at power; hot shutdown; start up hot shutdown; start up conditionsconditions

Safety layer approachSafety layer approach::• How many layers of safety still How many layers of safety still

remainremain• Power reactors during Power reactors during

shutdown; cold shutdownshutdown; cold shutdown• Fuel cycle facilities, research Fuel cycle facilities, research

reactors, accelerators, etcreactors, accelerators, etc

Identify how close the event was to causing actual Identify how close the event was to causing actual consequences by looking at the safety provisions: consequences by looking at the safety provisions:

What has failed? What has failed? and and What is left? What is left?

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INES Event Rating FormINES Event Rating Form

Fukushima-Fukushima-Daiichi Daiichi

units 1,2 and 3units 1,2 and 3Provisionally Provisionally Rated on 18Rated on 18thth

March at level 5March at level 5

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INES Event Rating FormINES Event Rating Form

Fukushima-Fukushima-Daiichi Daiichi

units 1,2 and 3units 1,2 and 3Provisionally Provisionally Rated on 12Rated on 12thth

April April at Level 7at Level 7

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How to Communicate INES EventsHow to Communicate INES Events

• NEWS: www-news.iaea.orgNEWS: www-news.iaea.org

• Events rated at INES level 2 and Events rated at INES level 2 and above above

• Events attracting international Events attracting international public interestpublic interest

• IAEA hosts and administrates the IAEA hosts and administrates the systemsystem

• Event reports are filed and Event reports are filed and updated by the participating updated by the participating countriescountries

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Questions & AnswersQuestions & Answers

Thank you for your time.Thank you for your time.

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