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IAEA Technical Meeting on Remediation Techniques and Strategies in Post-Accident Situations 13-17 June 2016

Application of ICRP Recommendations to the Protectionof People Living in Long-term Contaminated Areas after a

Nuclear Accident or Radiation Emergency

Per Hedemann-JensenHead of Department of Radiation and Nuclear Safety

Danish Decommissioning, Risø


• Review of reference levels before ICRP 103

• The need for a change of ICRP Publication 60

• Interpretation of reference levels in ICRP 103, 109 and 111

• ICRP versus IAEA recommendations

• A few concluding remarks

Outline


Review of Reference Levels before ICRP 103

• Recording Levels, above which a result should berecorded - lower values being ignored

• Investigation Levels, above which the cause or theimplications of the result should be examined

• Intervention Levels, in terms of avertable doses, abovewhich some remedial action should be considered

• Action Levels, above which some specified actionshould be taken

• Derived/Operational Intervention Levels, in terms ofmeasurable quantities corresponding to an InterventionLevel


Reference Levels recommended in ICRP 82

• Generic Reference Levels, expressed as an existing annual doseare useful when intervention is being considered in prolonged,existing exposure situations (total exposure)

• Specific Reference Levels, intervention levels and action levels forparticular prolonged exposure situations (incremental exposure)

• ICRP 82 is still valid


Historical review


Former ICRP recommendations (ICRP 60)


• some situations can be difficult to characterise aseither a practice or an intervention

• the difference between the concepts of dose limitsand intervention levels difficult to grasp

• affected populations are demanding the “samestandard” of radiation protection as in practices

• dose reduction below constraints in all situationsis easier to understand

Arguments for a change of ICRP 60

Practice versus intervention


New ICRP recommendations in 2007


New ICRP recommendations (ICRP 103)

AS SEEN BY THE ICRP !AS SEEN BY THE ICRP !


Justification and optimization of protective measures (ICRP 103)

Principle of justification:Any decision that alters the radiation exposure situationshould do more good than harm

Principle of optimization of protection:The likelihood of incurring exposures, the number ofpeople exposed, and the magnitude of their individualdoses should all be kept as low as reasonably achievable,taking into account economic and societal factors

Optimization only of justified protective actions:The process of optimization of protection is intended forapplication to those situations that have been deemed tobe justified


Reference Levels for Emergency exposureand Existing Exposure situations


Emergency and existing exposure situations

• naturally occurring radioactive materials in buildingmaterials

• radon in dwellings

• former activities

• weapons testing/military operations

• nuclear and radiological accidents

• waste and by-products from NORM-industries


Reference Levels from ICRP 103Reference LevelmSv or mSv/a Exposure Situations

20 – 100(emergency)

Nuclear accidents with dispersion of radioactivematerials to the environment (the Chernobyl- andFukushima-accident)Radiological accidents with dispersion of radioactivematerials to the environment (the Goiânia-accident)‘Nuclear attacks’ with radioactive materials

1 – 20(existing)

Radon in dwellingsHigh external background radiationHigh activity content in building materialsContaminated land from former practicesLong-term contaminated land from nuclear accidentsMilitary-industrial operationsAtmospheric tests of nuclear weapons


ICRP 103 statement on Averted Dose

The averted dose as recommended in earlier ICRP recom-mendations is the concept for the optimization of individualprotective measures

The ICRP now recommends focusing on optimization withrespect to the overall strategy, rather than the individualprotective measures

However, the levels of averted dose for optimization ofprotection in terms of individual protective measures may stillbe useful as inputs to the development of an overall protectionstrategy


ICRP 103 statements on Intervention Levelsand Reference Levels

Intervention Levels remain valuable for optimizationof individual countermeasures when planning aprotection strategy, as a supplement to ReferenceLevels for evaluation of protection strategies

Reference Levels refer to the residual dose afterimplementation of protection strategies and are usedto evaluate protection strategies, as opposed to theIntervention Levels which referred to averted dosesfrom individual protective actions


Task Group on ICRP Publication 111


Terms of reference of the Task Group onICRP Publication 111

• setting reference levels for planning long-term protec-tion strategies

• implementing optimized protective actions

• involving stakeholders in radiological protection

• developing radiation monitoring and health surveillance

• managing contaminated commodities


Reference Levels defined in ICRP 103

Section 5.9.2. Reference levelsPara 234: In emergency or existing controllable exposuresituations, the reference levels represent the level of dose orrisk, above which it is judged to be inappropriate to plan toallow exposures to occur, and for which therefore protectiveactions should be planned and optimized. The chosen value fora reference level will depend upon the prevailing circumstancesof the exposure situation under consideration.


Interpretation of reference levels in ICRP 103

ICRP 103, Executive Summary (t): Emphasis on optimisationusing reference levels in emergency and existing exposuresituations focuses attention on the residual level of doseremaining after implementation of protection strategies.

This residual dose should be below the reference level, whichrepresents the total residual dose as a result of an emergency,or in an existing situation, that the regulator would plan not toexceed.

Comment: This can be interpreted as the reference level is anupper target for the residual dose after the implementation ofan optimized protection strategy. It is supported by the ICRPFukushima statement and the radon example in Table 5 in ICRP103 (1 - 20 mSv/a is the Reference Level for the highestplanned residual dose from radon in dwellings).


ICRP statement on Fukushima 2011

}


Projected doses from all exposure pathways

For N exposure pathways, the total projected dose, Eproj,from all the exposure pathways can be determined as:

where Ƭi is the exposure time for the different exposurepathways.

N

ii

i

ttEE1 0

proj d)(


Averted doses from an optimized strategy

An optimized protection strategy, S = {f1, f2, f3, . . . , fN }, willreduce the individual doses from the different exposurepathways to a fraction, fi, of the initial doses resulting in atotal averted dose, Eavert:

N

i

T

Tii

ii

i

ttEfE1

avert d)()1(

where Ti is the starting time for the different protectiveactions, N, within the strategy and i is the duration ofeach of the individual protective actions within the strategy.


Residual doses after an optimized protection strategy

It is unclear how residual doses - after the implementationof a optimized protection strategy – automatically would bebelow a pre-selected reference level.

A justified/optimised protection strategy will determine themaximum net benefit and thereby the averted doses, whichdetermine the residual doses, Eres, being the differencebetween the projected and the avertable doses:

ttEfttE

EEE

i

N

i

T

Ti

N

ii

ii

i

i

d)()1(d)( 11 0

avertprojres


Protection strategy - fixed reference level

Annual dosePers

ons/

dose

inte

rval

Reference Level

Annual dosePers

ons/

dose

inte

rval

Reference Level

Time

The reference Level is not a moving target in time

Annual dosePers

ons/

dose

inte

rval

Reference Level


ICRP versus IAEA recommendations

ICRP recommends that Intervention Levels, IL, in termsof avertable doses are still valuable for optimization ofindividual countermeasures in planning of a protectionstrategy

IAEA recommends generic criteria and their derivedoperational quantities, Emergency Action Level, EAL,and Operational Intervention Level, OIL, based on thegeneric criteria for individual or combined protectiveactions


Safety Requirements No. GSR Part 7 Safety Guide No. GSG-2

IAEA recommendations


IAEA General Safety Requirements No. GSR Part 7Para. 4.28(3) On the basis of the outcome of the justification and theoptimization of the protection strategy, national generic criteria fortaking protective actions and other response actions, expressed interms of projected dose or of dose that has been received, shall bedeveloped with account taken of generic criteria. If the nationalgeneric criteria for projected dose or received dose are exceeded,protective actions and other response actions, either individually or incombination, shall be implemented.

(4) Once the protection strategy has been justified and optimized anda set of national generic criteria has been developed, pre-establishedoperational criteria (conditions on the site, emergency action levels(EALs) and operational intervention levels (OILs)) for initiating thedifferent parts of an emergency plan and for taking protective actionsand other response actions shall be derived from the generic criteria.


IAEA General Safety Guide No GSG-2

The Emergency Action Level, EAL, or the OperationalIntervention Level, OIL, are calculated quantities thatcorrespond to a generic criteria. If the EALs or OILs areexceeded, the appropriate protective action should bepromptly invoked.

EALs and OILs are typically expressed in termsmeasurable quantities e.g. dose rate, time integrated airconcentration, surface contamination density, or activityconcentration in food or water.


Operational Reference/Intervention Levels, ORL/OIL

Operational Reference/Intervention Levels, ORL/OIL,can be calculated from a Reference/InterventionLevel, RL/IL, and the dose per operational quantity:

quantity loperationaper dosedose in expressed IL/RLOIL/ORL


Operational Reference/Intervention Levels, ORL/OILExample on relocation:A Reference Level/Intervention Level, RL/IL, for relocation from acontaminated area (long-lived gamma-emitters) after a nuclearaccident based on justification/optimization of protection couldbe a received/averted dose more then 100 mSv/a (IAEA GSG-2)

μSv/h 30μSv/hper mSv/a 53

mSv/a 100

.OIL/ORL

The Operational Reference Level/Operational Intervention Level,ORL/OIL, for relocation - in terms of a -dose rate - is therefore:

mSv/a 3.5 0.4 h/a 8640 mSv/h 0010 .E

An outdoor -dose rate of 1 Sv/h results in an annual dose within the area of:


A few concluding remarks

Publication 111: 3.1. Justification of protection strategiesPara 27: Justification of protection strategies goes farbeyond the scope of radiological protection as they mayalso have various economic, political, environmental, social,and psychological consequences

Comment: If radiation protection guidance on justification ofprotection strategies is going to be overwhelmed ordiscounted by other considerations than radiologicalfactors, it raises the question of the ICRP recommendationsand other international guidance



Radiologicalprotectionumbrella

monetarycosts

socialvalues

anxiety reassurance

riskperception

politicalvalues

Societal umbrella (overall protection)

monetarycosts

anxiety

socialvalues

reassurance

riskperception radiological

protection

politicalvalues


A few concluding remarksReference levels for protection in existing exposuresituations should be developed from the outcome of thejustification and optimization of the protection and is not an‘off-the-shelf item’ that can be selected independently of theprevailing circumstances.

Optimization applies to protective measures that are justifiedand not to all levels of exposure above or below a referencelevel. Use of the justification principle together with theoptimization of a protection strategy through the use ofreference levels needs clarification.

The reference level range of 1 - 20 mSv/a in ICRP 103 is atvariance with the still valid recommendations in ICRP 82 andICRP 96 as far as the 1 - 10 mSv/a range is concerned. ICRP82 and ICRP 96 recommend a level of 10 mSv/a, below whichintervention is not likely to be justifiable. This needsclarification.



There is a conceptual difference between dose con-straints in ‘dose increment situations’ (planned exposuresituations) and reference levels in ‘dose decrementsituations’ (emergency and existing exposure situations).

Guidance on the development of reference levels inexisting exposure situations on the basis of the outcomeof the justification and the optimization of protectiveactions is needed.

ICRP has formed a Task Group 93: “Update of ICRPPublications 109 and 111” in the light of the lessons fromthe Fukushima accident and international developments.


Thank you for your attention

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