1. Emergency Response
Protective Actions
Day 10 – Lecture 3

2. 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
In order to respond correctly in an emergency situation, predefined criteria for action must be available.
This module will review the basic international concepts and criteria that should form part of the basis for predetermined criteria needed for an effective response.
In order to apply the method described in this publication, emergency planners should have a good understanding of the basic principles for response to a nuclear or radiological emergency. They should review the relevant international guidance [1, 2, 3, 4] beforehand.

3. 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

4. Practices and Interventions Systems for Radiation Protection
Each protective action should be justified
The level of protective actions resulting in dose subtraction should be optimized
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
For practices the ICRP recommendations include control of the source and limitation of exposure. Such a situation includes medical exposure, occupational exposure and exposure of the general public, and the protection system includes the practice justification, optimization of the protection and imposition of overall dose limits.
The dose limits recommended by the ICRP are intended for use in the control of practices. The use of these limits, or of any other pre-determined dose limits as the basis for deciding on intervention might involve measures that would be out of all proportion to the benefit obtained and would then conflict with the principle of justification. The ICRP therefore recommends against application of dose limits for deciding on the need for, or scope of, intervention. Nevertheless, at some level of dose, approaching that which would cause deterministic effects, some kind of intervention will become almost mandatory.
In some situations the sources, the pathways and the exposed individuals are already in place when the decisions about control measures are being considered, and protection can only be achieved by interventions, which always have some disadvantages. The system of protection for intervention includes justification of the intervention and the optimization of the form, scale and duration of the intervention so as to maximize the net benefit.
The wall on the slide between the two systems emphasizes that the systems are completely separated.

5. 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
Three general principles make the basis for making decisions on interventions.
Serious deterministic effects can be prevented if the doses to the public are kept below the thresholds for these effects. There will be some uncertainty in dose predictions, so that actions to prevent these effects will be taken somewhat below the threshold.
Intervention is justified when there is a net benefit for taking action. It is important to consider the benefits and penalties of intervention since the disadvantages of intervention for some protective actions may outweigh the advantages achieved by avoiding the exposure.
Intervention is optimized when the net benefit from a protective action is the maximum achievable point. An intervention level for each protective action can be chosen, above which the action is normally taken and below which the action is not normally taken. The value of the intervention level for each protective action should then be chosen in such a way as to produce the maximum net benefit.
The approach outlined in this lecture is consistent with the view that an explicit limitation of individual risk is not appropriate as a general principle for intervention because such a limitation, if applied inflexibly, could lead to decisions on intervention being taken that are not justified.
Nonetheless, it is appropriate to consider action levels for intervention, when justified and provided that they are not applied inflexibly, to avoid unacceptably high risks to individuals. These decisions are left for national authorities as an additional consideration that may modify some of the intervention levels. Authorities should bear in mind though that penalties increase rapidly with less and less dose saved for lower intervention levels.

6. 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
The factors entering the optimization process can be divided into those describing benefits from the protective action and those describing the harm. In analysing the inputs to the decision on the introduction of protective actions, it is necessary to decide on the relative importance of each factor. The most relevant factors are summarized on this slide.
The weighting to be attached to each of these factors are necessarily subjective and it has been difficult to agree internationally upon their exact values. In any case the importance of some of the factors will vary by the site and nature of the accident, thus making it difficult to generalize. Nevertheless, the dominant factors are those related to radiological protection principles, and to psychological and political factors.
Socio-political and psychological factors indeed may well contribute to, or even dominate, some decisions. The competent authorities responsible for radiation protection should therefore be prepared for the radiation protection input (justification and optimization of the proposed protective actions on radiological grounds) to the decision making process in a systematic manner, indicating all the radiological factors already considered in the analysis of the protection strategy. In the decision process, the radiological protection and the political factors should each be taken into account only once to avoid the same political factors being introduced in several places.

7. Projected Dose Dose rate Projected dose
Time after start of the accident
Dose rate
Projected
dose
The projected dose is the total dose from the start of the exposure or release until the end of the implementation of a protective measure. As we will see later, the need for protective actions is generally determined by comparing the doses avertable by introducing the protective action to an appropriate intervention level. In some circumstances it is also necessary to consider the projected dose in relation to the threshold dose for deterministic effects.

8. Action Level of Dose for Acute Exposure to 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
The table gives action levels of dose for acute exposure to organ or tissue at which intervention is expected to be taken under any circumstances. These levels are from the IAEA international requirements (GS-R-2) ref. 2 and are based on earlier standards. These levels are used to indicate when protective action (intervention) would be warranted under any conditions (e.g during severe snow storm). These action levels are set at doses approaching those at which deterministic health effects would be expected. However, these levels are only applicable for low LET radiation and are not approved for use when considering intake of high LET emitters (e.g. Pu). How to address high LET intake will be discussed later.
[3] Appendix 2, Table A2-I, page 116.

9. Avertable Dose Time after the start of the accident Dose rate
At a particular time, it is supposed that a protective action is introduced such that the dose rate for the individuals affected is significantly reduced. After a period of time, the protective action is withdrawn and the dose rates increase again. The dose averted by the protective action is the integrated dose rate over the period of time [t2 – t1] to which a person would be subject in the absence of the protective action, minus the integrated dose rate to which a person would be subject if the protective action is taken.
Since protective actions will normally be invoked at levels of dose at which the concept of “effective” dose applies, the intervention levels of avertable dose can be expressed in units of sieverts (Sv).
In many practical cases, where a protective action is very effective at reducing doses, the avertable dose will be equal to the entire projected dose from the same pathways over the same time period, but this will not always be the case.
The avertable dose is functionally related to a specific radionuclide, specific pathway of exposure and specific protective action.

10. 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
Only the avertable doses from those pathways that can be influenced by the protective action should normally be taken into account in judging whether to take action or not. Intervention cannot reduce doses already received, and it is therefore not appropriate to include doses already received before a protective action can be taken when applying an intervention level expressed in terms of avertable dose.
In the management of accidents, there are two distinct phases in which optimization of protective actions should be considered. In the phase of planning and preparedness, prior to any actual event, a generic optimization of protective actions should be studied, based on generic accident scenarios. This should result, for each protective action and each selected scenario, in an optimized generic intervention level (GIL), which is meant to be the first criterion for action to be used immediately and for a short time after the occurrence of an accident.
Some time after a real event, specific information on the nature and likely consequences of the accident would become available. In this case, a more precise and specific optimization analysis can be carried out on the basis of actual data and efficiency of protective actions. This could result in a specific intervention level for each protective action, to be used as a criterion in the medium and long term. However, in many cases the optimization will be constrained by socio-political factors, which may make it difficult to alter the generic intervention levels unless there are overriding reasons.

11. 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
International guidance [2] specifies “generic intervention levels” (GILs), at which some urgent and longer term protective actions should be taken by the public and “generic action levels” (GALs), at which controls should be placed on food and water.

12. 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)
The GILs and GAL were selected so that the protective action would do more good than harm: that is, the benefits of averting a dose will be greater than the penalty incurred by applying the protective action. Notably, this also means that taking protective action at considerably lower or higher values could increase the overall detriment to the public or workers. These GILs and GALs are justified and optimized for conditions under which the protective action will not be overly hazardous. Therefore, during conditions such as a severe snow storm, evacuation would be justified to avert a higher dose than those in the international guidance.

13. GILs for Urgent Protective Actions Table AI-I
(dose avertable)
Sheltering
10 mSv
in 2 days
Evacuation
50 mSv
in 1 week
Iodine prophylaxis
100 mGy
Generic intervention levels for implementation of urgent protective action. Urgent protective actions are those actions for which their effectiveness will be decreased by delay in implementation. Urgent protective actions include: sheltering, evacuation and iodine prophylaxis.
The generic optimized intervention level for sheltering is 10 mSv of avertable dose in a period of not more than 2 days. Authorities may wish to advise sheltering at lower intervention levels for shorter periods or so as to facilitate further countermeasures, e.g. evacuation.
The generic optimized intervention value for temporary evacuation is 50 mSv of avertable dose in a period of not more than 1 week. Authorities may wish to initiate evacuation at lower intervention levels for shorter periods, and also where evacuation can be carried out quickly and easily, e.g. for small groups of people. Higher intervention levels may be appropriate in situations where evacuation would be difficult, e.g. for large population groups or if there is inadequate transport.
The generic optimized intervention value for iodine prophylaxis is 100 mGy of avertable committed absorbed dose due to radioiodine. For practical reasons, one intervention level is recommended for all age groups.
The levels can be found in [3] Appendix 1, pages

14. 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
The generic optimized intervention levels for initiating and terminating temporary relocation are 30 mSv in a month and 10 mSv in a month, respectively. If the dose accumulated in a month is not expected to fall below this level within a year or two, permanent resettlement with no expectation of return to homes should be considered. Permanent resettlement should also be considered if the lifetime dose is projected to exceed 1 Sv.
These levels can be found in [3] Table A1-III, page 115.

15. Generic Action Levels for Foodstuffs Table 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
The levels shown in here apply to situations where alternative food supplies are readily available. Where food supplies are scarce, higher levels can apply. The levels are for food prepared for consumption, and would be unnecessarily restrictive if applied to dried or concentrated food prior to dilution or reconstitution. For practical reasons, the criteria for separate radionuclide groups should be applied independently to the sum of the activities of the radionuclides in each group.
Classes of food that are consumed in small quantities (e.g. less than 10 kg per person per year), such as spices, which represent a very small fraction of the total diet and would make very small additions to individual exposures, may have action levels ten times higher than those for major foodstuffs. The table is based on, and consistent with, the Codex Alimentarius Commission's guideline levels for radionuclides in food moving in international trade following accidental contamination (Joint FAO/WHO Food Standards Programme, Codex Alimentarius Commission, Codex Alimentarius, Volume 1 (1991) Section 6.1, ‘Levels for Radionuclides’), but it is limited to the nuclides usually considered relevant to emergency exposure situations. The use of these levels is intended to be limited to the first year after a nuclear or radiological emergency.
[3] Table A1-III, page 115

16. 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
International guidance for emergency workers (GS-R-2) [2] states that when undertaking intervention under these circumstances, all reasonable efforts shall be made to keep doses to workers below twice the maximum single year dose limit, except for life saving actions, in which every effort shall be made to keep doses below ten times the maximum single year dose limit in order to avoid deterministic effects on health. In addition, workers undertaking actions in which their doses may approach or exceed ten times the maximum single year dose limit shall do so only when the benefits to others clearly outweigh the risks.

17. 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
This summarizes the guidance for emergency workers provided in [3] appendix III, which is based on GS-R-2. Guidance for emergency workers serves as a reference and not as a limit. Any worker that may be expected to receive a dose above 100 mSv should be a volunteer and should have been provided with sufficient information on the risks of such exposure to allow them to make an informed decision when volunteering. These are the total effective dose including the dose from intake (e.g. inhalation) and external exposure.

18. Importance of Establishing Criteria (OILs)
Major lessons:
Establish in advance, operational criteria for the instruments used
Act on instrument readings not GILs or GALs
However, this international guidance (GILs and GALs) is not designed to be used during an emergency; the levels cannot be promptly measured in the field and do not address facility conditions. One of the major lessons from past emergencies is that established criteria for instruments is required for instruments which will be used during an emergency.

19. 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)
The international guidance (GILs and GALs) should be used to develop, in advance, operational intervention levels (OILs) and other criteria, e.g. emergency action levels (EALs), which can easily be measured during an emergency (e.g. expressed as dose rate), and with which the need for protective action can be rapidly ascertained. The Chernobyl accident showed that developing OILs during an emergency that are consistent with international guidance is very difficult due to political pressure and public mistrust. In addition, not having internationally harmonized OILs in place before an emergency would result in different protective actions being taken by States for the same measured levels.
This is what happened worldwide following the Chernobyl accident when establishing controls on contaminated food was difficult to explain to the public. Therefore, OILs should be developed in advance as part of the planning process.

20. 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
Here are some examples of OILs. These are for the ambient dose rate measured 1 meter above the ground .
The first two are for the mixture of radionuclides that would be deposited from a reactor release and come from TECDOC-955. Therefore, if following a reactor accident you measured 1 mSv/h from ground deposition than that area should be evacuated because that action would avert 50 mSv in a week (the GIL for evacuation) If you measured 1 Sv/h than the food grown there should be restricted until analysed because the concentrations in the food may be above the GALs.
The third OIL is for a radiological emergency and comes from TECDOC Therefore, if following a radiological emergency you measured 100 Sv/h from ground deposition than that area should be evacuated and cordoned.

21. Expanded Guidance
Current international guidance was found to be incomplete during past emergencies
TECDOC – proposes an extended framework of generic criteria that is intended to address the lessons from past emergencies
An examination of past emergencies showed the current international guidance did not provide an adequate basis for all the decisions that should have been based on radiation protection principles (e.g. who should receive long term medical follow-up). As a first step in addressing this need, TECDOC (the framework) [4] was published for comment in This TECDOC proposed an expanded set of generic reference levels (GRLs) that can form a basis for developing the operational levels needed for making decisions concerning protective and other actions. These GRLs attempt to:
address the lessons learned from past emergencies,
addresses the published emergency preparedness requirements (GS-R-2),
provides an internally consistent foundation for the application of radiation protection principles for the conceivable range of protective and other actions, and
provides a basis for a common language explanation to the public and to public officials.
This document was undergoing review in 2005.

22. 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

23. Where to Get More Information
IAEA, Method for developing arrangements for response to a nuclear or radiological emergency, EPR-METHOD, IAEA, Vienna (2003)
IAEA, Development of extended framework for emergency response criteria, Interim report for comments, TECDOC-1432, IAEA, Vienna (2005)
1) What are the basic principles of intervention?
2) List the beneficial and harmful factors entering optimization?
3) What is projected dose?
4) What is avertable dose?
5) With respect to international guidelines, what is the GIL for sheltering and evacuation?
6) Are these values adopted in your national guidelines?
7) What is the highest priority of emergency workers in the case of a radiation accident?
a) minimise dispersion of radioactive substances?
b) fire fighting?
c) life saving?
8) What is the GAL for Sr-90 and I-131?
9) What is the total effective dose guidance for life saving actions?