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