intervention for chronic and emergency exposure situations general principles and types of events...
TRANSCRIPT
Intervention for Chronic and Emergency Exposure SituationsIntervention for Chronic and Emergency Exposure Situations
General Principles and Types of EventsGeneral Principles and Types of Events
Prolonged Prolonged (Chronic) (Chronic) Radiation ExposureRadiation ExposureLectureLecture
IAEA Post Graduate Educational Course in Radiation Protection and Safety of Radiation Sources
Module X.1 - General Principles and Types of Events 2
IntroductionIntroduction
Prolonged (chronic) exposuresProlonged (chronic) exposures are are adventitiously and persistently incurred adventitiously and persistently incurred by the public over long periodsby the public over long periods
This lesson provides guidance on the This lesson provides guidance on the application of the ICRP’s system of application of the ICRP’s system of radiological protection to situations of radiological protection to situations of prolonged (chronic) exposureprolonged (chronic) exposure
Module X.1 - General Principles and Types of Events 3
ContentContent
Prolonged exposureProlonged exposure Basic Basic frameworkframework The ICRP System for radiological The ICRP System for radiological
protectionprotection Specific reference levelsSpecific reference levels Generic reference levels Generic reference levels Specific prolonged exposure situationsSpecific prolonged exposure situations SummarySummary
Module X.1 - General Principles and Types of Events 4
Prolonged ExposureProlonged Exposure
Delivered by the “natural” sourcesDelivered by the “natural” sources Cosmic radiationCosmic radiation TerrestrialTerrestrial Indoor radonIndoor radon NORM from extractive industriesNORM from extractive industries
Delivered by the “artificial” sourcesDelivered by the “artificial” sources Current Current practicespractices Past activitiesPast activities and events and events AccidentsAccidents CommoditiesCommodities
Module X.1 - General Principles and Types of Events 5
Basic FrameworkBasic FrameworkRadiation quantitiesRadiation quantities
The relevant dosimetric quantity:The relevant dosimetric quantity: annual effective dose [mSv]annual effective dose [mSv]
The subsidiary quantities:The subsidiary quantities: existing annual doseexisting annual dose additional annual doseadditional annual dose averted annual doseaverted annual dose avertable annual doseavertable annual dose projected doseprojected dose residual doseresidual dose
Module X.1 - General Principles and Types of Events 6
Basic FrameworkBasic FrameworkRadiation Induced Health EffectsRadiation Induced Health Effects
The annual dose for common prolonged The annual dose for common prolonged exposure situations: well below the exposure situations: well below the threshold for deterministic effectsthreshold for deterministic effects
The stochastic effects are the only The stochastic effects are the only radiation-induced health effects of radiation-induced health effects of concern concern
Module X.1 - General Principles and Types of Events 7
Basic FrameworkBasic FrameworkSystem of Radiological ProtectionsSystem of Radiological Protections
Scope: the ICRP system of radiological Scope: the ICRP system of radiological protection applies to protection applies to controllable controllable exposuresexposures
Aim: to provide an appropriate standard of Aim: to provide an appropriate standard of protection for humansprotection for humans
Categorisation: Categorisation: practicespractices and and interventionsinterventions
Module X.1 - General Principles and Types of Events 8
PracticesPractices
A practice may add annual doses to the A practice may add annual doses to the existing annual doseexisting annual dose Transitory exposures (direct irradiation Transitory exposures (direct irradiation
and short-lived radionuclides)and short-lived radionuclides) Prolonged exposures (long-lived Prolonged exposures (long-lived
radionuclides)radionuclides) The ICRP system of radiological The ICRP system of radiological
protection for practices is concerned with protection for practices is concerned with the additional annual dose attributable to the additional annual dose attributable to practicepractice
Module X.1 - General Principles and Types of Events 9
Additional Annual DoseAdditional Annual Dose
Time
Pre-practice existingannual dose
Additional (prolonged)annual dose attributableto the practice, E(excluding the transitory doses,which would have ceased afterthe termination of the practice)
Post-practiceexistingannual dose
Introduction, operation, anddecommissioning of a practice
Exi
stin
g a
nn
ual
do
se
Module X.1 - General Principles and Types of Events 10
Application of the ICRP SystemApplication of the ICRP SystemPracticesPractices
Justification of the practiceJustification of the practice Justifying practices involving prolonged Justifying practices involving prolonged
exposureexposure Optimisation of radiological protectionOptimisation of radiological protection
Optimising protection of sources Optimising protection of sources delivering prolonged exposuredelivering prolonged exposure
Limitations of individual dosesLimitations of individual doses Limiting individual doses attributable to Limiting individual doses attributable to
prolonged exposure (prolonged exposure (dose constraintsdose constraints and and dose limitsdose limits))
Module X.1 - General Principles and Types of Events 11
Recommended LevelsRecommended LevelsIndividual Dose RestrictionsIndividual Dose Restrictions
0.01
0.1
0.3
1DOSE LIMIT
EXEMPTION
OP
TIM
ISA
TIO
N
DO
SE
CO
NS
TR
AIN
T
ADDITIONAL ANNUALDOSE [mSv]
EXISTING ANNUALDOSE [mSv]
'NATURAL'BACKGROUND
Very high
Typicalelevated
Globalaverage 2.4
10
100
1 mSv
Module X.1 - General Principles and Types of Events 12
InterventionsInterventionsin prolonged exposure situationsin prolonged exposure situations
Interventions are intended to reduce the Interventions are intended to reduce the existing annual dose (averting annual existing annual dose (averting annual dose components) bydose components) by Removing existing doseRemoving existing dose Modifying pathwaysModifying pathways Reducing the number of exposed Reducing the number of exposed
peoplepeople
Module X.1 - General Principles and Types of Events 13
Averted Annual DoseAverted Annual Dose
Time
Pre-interventionexistingannual dose
Post-interventionexistingannual dose
Intervention
Averted annual dose bythe intervention, - E
Exi
stin
g a
nn
ual
do
se
Module X.1 - General Principles and Types of Events 14
Application of ICRP SystemApplication of ICRP SystemInterventions - Prolonged ExposureInterventions - Prolonged Exposure
Justification of interventionJustification of intervention
Optimisation of protective (remedial) Optimisation of protective (remedial) actionsactions
Module X.1 - General Principles and Types of Events 15
JustificationJustification
Two extremesTwo extremes The existing annual dose is low enough The existing annual dose is low enough
to make intervention unexpected (not to make intervention unexpected (not likely to be justifiable)likely to be justifiable)
The existing annual dose is so high as The existing annual dose is so high as to justify intervention under almost any to justify intervention under almost any circumstancescircumstances
Justification is crucial somewhere Justification is crucial somewhere between these extremesbetween these extremes
Module X.1 - General Principles and Types of Events 16
DisadvantagesDisadvantages
Without interventionWithout intervention the existing individual and collective the existing individual and collective
annual dosesannual doses
the anxieties they causethe anxieties they cause
the consequent political pressuresthe consequent political pressures to to remedy the situationremedy the situation
Module X.1 - General Principles and Types of Events 17
Disadvantages – Cont’dDisadvantages – Cont’d
Intervention will in addition introduceIntervention will in addition introduce costs, harm, and inconveniencescosts, harm, and inconveniences the social disruptionthe social disruption the occupational doses incurred by the occupational doses incurred by
those implementing the intervention those implementing the intervention
Module X.1 - General Principles and Types of Events 18
Advantages of InterventionAdvantages of Intervention
Averted individual and collective doses Averted individual and collective doses (reduction in the existing annual doses)(reduction in the existing annual doses)
ConsequentlyConsequently reduction in the risk of radiation health reduction in the risk of radiation health
effectseffects reassurance gained by the populationreassurance gained by the population decrease in the political pressure and in decrease in the political pressure and in
the anxiety created by the populationthe anxiety created by the population
Module X.1 - General Principles and Types of Events 19
OptimisationOptimisation
Not only a positive net benefit, but also a Not only a positive net benefit, but also a maximisedmaximised net benefit net benefit
Conceptually no difference from Conceptually no difference from optimising protection of sources within optimising protection of sources within practicespractices
The optimum form, scale, and duration of The optimum form, scale, and duration of the protective actions should be selected the protective actions should be selected from the justified options of interventionfrom the justified options of intervention
Module X.1 - General Principles and Types of Events 20
Specific Reference LevelsSpecific Reference Levels
Intervention levelsIntervention levels
Action levelsAction levels
Intervention exemption levelsIntervention exemption levels
Module X.1 - General Principles and Types of Events 21
Generic Reference LevelsGeneric Reference Levels
The existing annual dose – conceptually The existing annual dose – conceptually can be used to establish can be used to establish generic reference generic reference levelslevels for intervention for intervention
The quantity should be used with cautionThe quantity should be used with caution Preference is given to Preference is given to specific reference specific reference
levelslevels based on avertable doses based on avertable doses
Module X.1 - General Principles and Types of Events 22
Recommended Generic Reference Recommended Generic Reference LevelsLevels
Generic reference level below which Generic reference level below which intervention is not likely to be justifiable:intervention is not likely to be justifiable: existing annual dose existing annual dose about 10 mSvabout 10 mSv
Generic reference level for establishing Generic reference level for establishing protective actions under nearly any protective actions under nearly any conceivable circumstances:conceivable circumstances: existing annual dose existing annual dose rising towards 100 rising towards 100
mSvmSv
Module X.1 - General Principles and Types of Events 23
PerspectivesPerspectivesEXISTING ANNUAL
DOSE [mSv]'NATURAL'BACKGROUND
Very high
Typicalelevated
Globalaverage 2.4
10
100
GENERIC REFERENCELEVELS
Intervention almostalways justifiable
Intervention maybe necessary
Intervention unlikelyto be justifiable
Module X.1 - General Principles and Types of Events 24
Specific Prolonged Exposure Specific Prolonged Exposure SituationsSituations
High levels of prolonged exposure to High levels of prolonged exposure to natural background radiationnatural background radiation
Long-lived radioactive residues in human Long-lived radioactive residues in human habitatshabitats
Discontinuation of intervention after an Discontinuation of intervention after an accidentaccident
Radioactive substances in commoditiesRadioactive substances in commodities
Module X.1 - General Principles and Types of Events 25
High Levels of Prolonged Exposure to High Levels of Prolonged Exposure to Natural Background RadiationNatural Background Radiation
Radon in dwellingsRadon in dwellings
Natural gamma radiation emitters in Natural gamma radiation emitters in building materialsbuilding materials
Natural gamma radiation emitters in the Natural gamma radiation emitters in the groundground
Module X.1 - General Principles and Types of Events 26
Long-lived Radioactive Residues in Long-lived Radioactive Residues in Human HabitatsHuman Habitats
Radioactive residues from practicesRadioactive residues from practices
Radioactive residues from past human Radioactive residues from past human activities and eventsactivities and events
Situations of potential exposureSituations of potential exposure
Module X.1 - General Principles and Types of Events 27
Discontinuation of Intervention After Discontinuation of Intervention After an Accidentan Accident
When exposures have decreased to the When exposures have decreased to the action levels that would have prompted action levels that would have prompted the intervention orthe intervention or
When the generic reference level of When the generic reference level of existing annual dose below which the existing annual dose below which the intervention is not likely to be justifiable intervention is not likely to be justifiable could provide a basis for discontinuing could provide a basis for discontinuing interventionintervention
Module X.1 - General Principles and Types of Events 28
Radioactive Substances in Radioactive Substances in CommoditiesCommodities
Radionuclides may be of natural or Radionuclides may be of natural or artificial originartificial origin
As a result of natural processes or as As a result of natural processes or as direct result of human activitiesdirect result of human activities
A generic intervention level of around 1 A generic intervention level of around 1 mSv is recommended for the individual mSv is recommended for the individual annual doseannual dose
The control of commodities after an The control of commodities after an accidentaccident
Module X.1 - General Principles and Types of Events 29
SummarySummary
The ICRP system of protection of the The ICRP system of protection of the public against prolonged (chronic) public against prolonged (chronic) exposures provide the radiological exposures provide the radiological protection philosophy for these topicsprotection philosophy for these topics
The numerical values for specific and The numerical values for specific and generic reference levels are just starting generic reference levels are just starting points for the discussions leading up to points for the discussions leading up to the decisions neededthe decisions needed
Quantitative recommendations for Quantitative recommendations for prolonged exposure situations must be prolonged exposure situations must be interpreted with extreme cautioninterpreted with extreme caution
Module X.1 - General Principles and Types of Events 30
Where to Get More InformationWhere to Get More Information
INTERNATIONAL COMMISION ON INTERNATIONAL COMMISION ON RADITION PROTECTIONRADITION PROTECTION
Protection of the Public in Situations of Protection of the Public in Situations of Prolonged Radiation ExposureProlonged Radiation Exposure
Annals of the ICRP, ICRP Publication 82, Annals of the ICRP, ICRP Publication 82, Pergamon, 2000 Pergamon, 2000