iaea international atomic energy agency emergency response protective actions day 10 – lecture 3
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IAEA
Introduction
• In order to respond correctly in an emergency situation, predefined criteria for action must be available
• This lecture covers the basic
internationally accepted intervention
criteria
IAEA
Content
• Basic principles of intervention• Optimization of intervention• Projected and avertable dose• Action level dose for organs and tissue• Principles for intervention levels• Urgent protective action levels• Generic action levels for foodstuffs• Emergency worker protection guidance• Classes of emergency related work
IAEA
Practices and InterventionsSystems for Radiation Protection
• Each practice should be justified
• The doses adding up in a practice should be kept as low as reasonably achievable
• The sum of doses in a practice should be kept below specified dose limits
• Each protective action should be justified
• The level of protective actions resulting in dose subtraction should be optimized
IAEA
Basic Principles of Intervention
• All possible efforts should be made to prevent serious deterministic health effects and to reduce the occurrence of stochastic effects
• Intervention should be justified, such that the introduction of protective action should achieve more good than harm
• Levels at which intervention is introduced and at which it is later withdrawn should be optimized, so that protective action will produce the maximum net benefit
IAEA
Factors Entering Optimization
Benefit
• Avertable individual risk
• Avertable collective risk
• Reassurance
Harm• Individual physical risk• Collective physical risk• Monetary costs• Social disruption• Individual disruption• Countermeasure
anxiety• Worker risk
IAEA
Action Level of Dose for Acute Exposure to Organ or Tissue
Organ or tissue Action level of dose: Projected absorbed dose to the organ or tissue in less than 2 days (Gy)
Whole body 1
Lung 6
Skin 3
Thyroid 5
Lens of the eye 2
Gonads 3
IAEA
Principles for Intervention Levels
• Dose quantity to express the intervention level is the avertable dose
• Only pathways and doses that can be influenced by protective action should be taken into account
• Estimate of avertable doses should be as realistic as possible and for an average member of affected population
IAEA
Application
International guidance specifies:
• “Generic Intervention Levels”
(GILs), at which urgent and
long term protective actions
should be taken
• “Generic Action Levels” (GALs), at which controls should be placed on contaminated food
IAEA
GIL and GALs
• GIL and GALs set so that action would do more good than harm
• Taking action at a considerably lower level could increase overall harm to the public
• Not applicable if protective action is overly hazardous or disruptive (e,g. evacuation during a snow storm justified at a higher GIL)
IAEA
GILs for Urgent Protective ActionsTable AI-I
Protective action GIL
(dose avertable)
Sheltering 10 mSv
in 2 days
Evacuation 50 mSv
in 1 week
Iodine prophylaxis 100 mGy
IAEA
Generic Action Levels for Relocation And Resettlement Table A1-II
Protective action GIL
(Dose avertable)
Temporary relocation
30 mSv/month
Terminating temporary relocation
10 mSv/month
Permanent resettlement
1000 mSv/life time
IAEA
Generic Action Levels for FoodstuffsTable A1-III
Radio nuclides in foods destined for
general consumption
GAL
kBq/kg
Cs-134, Cs-137,
I-131, Ru-103,
Ru-106, Sr-89
1
Sr-90 0.1
Am-241, Pu-238,
Pu-239, Pu-240
0.01
IAEA
Protection of Workers Undertaking an Intervention (GS-R-2)
• No worker undertaking an intervention shall be exposed in excess of the maximum single year dose limit for occupational exposure except:
• For the purpose of saving life or preventing serious injury
• If undertaking actions intended to avert a large collective dose
• If undertaking actions to prevent the development of catastrophic conditions
IAEA
IAEA Guidance for an Emergency Worker Appendix 3
Task Total effective dose guidance
(mSv)
Life saving actions >500
Prevent the development of catastrophic conditions
>100
Emergency phase intervention >50
Longer term recovery operations and work not directly connected with an accident
Occupational exposure guidance
IAEA
Importance of Establishing Criteria (OILs)
Major lessons:
• Establish in advance, operational criteria for the instruments used
• Act on instrument readings not GILs or GALs
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GIL, GAL and Worker Guidance
• Not designed to be used during an emergency
• Must develop observable criteria to be used during an emergency• Operational intervention levels (OILs)
• Worker turn back guidance
• Measurable during an emergency with available instruments (e.g. expressed as dose rate)
IAEA
Example OILs - Dose Rates at 1 m Above Ground
Reactor release (TECDOC-955)
• Evacuate 1 mSv/h
• Restrict Food 1 Sv/h
Radiological emergency (TECDOC-1162)
• Cordon 100 Sv/h
IAEA
Expanded Guidance
• Current international guidance was found to be incomplete during past emergencies
• TECDOC - 1432 – proposes an extended framework of generic criteria that is intended to address the lessons from past emergencies
IAEA
Summary
• EP guidance is based partly on international intervention guidance • Action levels
• GILs
• GALs
• International guidance • Not useable during an emergency - need OILs
• May not address all conditions
• Taking action at lower levels could do more harm than good
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