Chapter 6 Protective action response strategy

6.1 General

This chapter examines the protective action response strategy which covers the available range of precautionary and protective measures as well as the evolution of decision-making as the radiation event progresses.

6.2 Guiding Principles for Protective Action Decision-Making

6.2.1 Protective actions to mitigate nuclear emergencies and radiological emergencies include both precautionary measures (Section 6.4) and protective measures (Section 6.5).

6.2.2 Protective actions are complementary to each other, and may be applied in combination as a protective action response strategy, as appropriate to the situation, taking into account their respective efficacies and limitations.

6.2.3 Protective actions should be applied so as to prevent any increased public exposure to radiation. In practice, this may not always be justified as protective actions may entail risks and costs (e.g., psychosocial and economic). It is therefore necessary to justify and optimize (Section 6.9) the application of protective actions so as to minimize the total risk or detriment involved.

6.2.4 In a nuclear emergency, if a protective measure is warranted at any boundary of a response sector in the Detailed Planning Zone, it should be applied to the whole response sector.

6.2.5 In a nuclear emergency, if a protective measure is warranted in the Detailed Planning Zone, it should be applied to the entire ring of sectors in order to ensure protection when winds are shifting.

6.2.6 The PEOC Commander, as operational lead for the off-site response (Section 5.6), has the authority on behalf of the province for protective action decision-making and shall direct the implementation of protective measures as appropriate. Where a protective measure is warranted, the PEOC Commander shall issue an operational directive or, if an emergency is declared, the PEOC Commander shall promulgate an emergency order for the protective measure(s) and define the applicable area.

6.2.7 Detailed information regarding all of the protective measures detailed below shall be developed and communicated during the preparedness stage through public awareness and education (Section 3.2.10), and during the emergency phase through public direction (Section 7.3) and emergency public information (Section 7.4).

6.3 Protective Action Decision-Making for Nuclear Emergencies

6.3.1 Due to the nature of nuclear reactor emergencies, where the hazard and its location are known and, the extent of the hazard is verifiable, protective action decision-making can be categorized according to the following emergency phasing:

1. early phase
2. intermediate phase
3. transition to recovery phase

6.3.2 Early Phase

1. Protective measures should be instituted based on a conservative estimate of the situation because time or data may not be available to carry out a comprehensive assessment of imminent risk. These protective measures shall be detailed in the applicable implementing plan and may include sheltering-in-place, evacuation and Iodine Thyroid Blocking.
2. Decision-making, based on generic criteria (Annex E, Appendix 1) should commence before exposure is expected to occur (e.g. when time and data are available) with an assessment of projected doses to determine the need for any protective and precautionary measure(s) listed in Table 6.1.
3. The additional measures listed below are not associated with a numerical intervention level or generic criteria and may also be directed in combination with any of the numerically associated protective and precautionary measures listed in Table 6.1:
   1. protective clothing
   2. respiratory protection
   3. self-decontamination
4. Precautionary measures (Section 6.4) should be directed in advance of, or in combination with protective measures, as appropriate, to facilitate implementation.

6.3.3 Intermediate Phase

1. The intermediate phase begins once uncontrolled releases have ended permitting environmental radiation monitoring to be undertaken.
2. Relocation is the preferred protective measure during the intermediate phase to prevent external exposure from deposited radioactive particles (e.g. ground contamination) as well as to prevent internal exposure from inhalation of radioactive particulates.
3. Ingestion control measures shall be directed as appropriate based on the results of environmental field monitoring of food, milk and water.
4. A technical assessment of actual radiation monitoring results and the application of Operational Intervention Levels (OILs) (Annex E, Appendix 2) should inform the decision-making process to determine the need for both ingestion and exposure control measures.
5. The developing situation should be continuously re-assessed and appropriate decisions made on applying protective measures as well as rescinding those no longer necessary.
6. All technical assessments should be evaluated in the context of operational factors and public policy (e.g. psychosocial and economic) considerations. Such considerations should provide an overall assessment of the risks and costs associated with various protective measures. The final decision on protective measures should be optimal and most appropriate for public safety and welfare (Section 6.9).

6.3.4 Transitioning to Recovery Phase

1. Emergency plans shall describe the process to transition from emergency response to recovery including the requirements to establish a recovery organization and to develop a recovery plan.
2. The transition to recovery may begin during the intermediate phase and may proceed independently of intermediate phase activities.
3. Recovery phase decision-making should focus on the revision or rescinding of protective measures imposed during the previous phases with the goal of reducing environmental radiation to acceptable levels, improving living conditions and ultimately restoring conditions back to normal.
4. Recovery phase decision-making should be based on the principle of optimization of the radiation situation (Section 6.9).
5. The imposition and rescinding of protective measures, as well as the distinction between the three phases, may not be uniform across the affected area as contamination levels in each sector may be different.

6.4 Precautionary Measures

6.4.1 Precautionary measures should be implemented during the early and intermediate phases, either in advance of, or in combination with exposure control protective measures to facilitate their implementation. Unlike protective measures, precautionary measures are not associated with a numerical intervention level.

6.4.2 The PEOC Commander shall direct precautionary measures as appropriate, in consultation with the affected Designated Municipalities where time permits.

6.4.3 Precautionary measures shall be directed via emergency bulletins (see Section 7.3.2) issued by the PEOC Commander to the affected public.

6.4.4 Precautionary measures include:

1. closing of beaches, recreation areas, etc.
2. closing of workplaces and schools
3. suspension of non-critical patient admissions in hospitals
4. entry control
5. clearing milk storages of dairy farms
6. banning consumption of any item of food or water that may have been exposed outdoors
7. banning consumption and export of locally produced milk, meat, produce, and milk-and meat-producing animals
8. removing milk-and meat-producing animals from outside pasture and exposed water sources

6.5 Protective Measures for Exposure Control

6.5.1 General

1. Protective measures can minimize exposure by:
   1. reducing or avoiding exposure to a radioactive plume
   2. reducing or avoiding exposure to ground contamination (or re-suspended contamination)
2. Some or all of the protective measures may be implemented during a radiological emergency and are implemented, for the most part, during the early and intermediate phases of a nuclear emergency (Section 5.9).
3. The protective measures detailed below are associated with intervention levels (Annex E) to guide decision-makers on their implementation to protect public safety. Additional protective measures can be recommended to enhance public safety during a response, such as the use of protective clothing or respiratory protection. Such measures are discussed in Section 6.8 and listed in Table 6.1.

6.5.2 Iodine Thyroid Blocking

1. General
   1. Iodine Thyroid Blocking involves the ingestion of potassium iodide (KI) pills to prevent the uptake of radioactive iodine by the thyroid gland during a radioactive release.
   2. Iodine Thyroid Blocking shall be directed by the CMOH as appropriate in coordination with the PEOC and the local Medical Officer of Health and is normally undertaken during the early or intermediate phase.
   3. Iodine Thyroid Blocking provides protection against just one radioisotope present in a radioactive release, radioiodine. As a result, this measure is optimally used in combination with other protective measures, such as sheltering-in-place or evacuation, in order to protect the whole body from all radioisotopes.
   4. KI pills should be ingested 2-6 hours prior to or just after exposure to radioiodine in order to optimize protection from radioiodine,
   5. A single KI dose lasts approximately 24 hours and should be taken daily until the risk of significant exposure to radioiodine no longer exists. Note: certain populations i.e., pregnant or breastfeeding women, and infants <1-month-old should only take one dose of KI.
   6. KI pill ingestion should be replaced, as a protective measure against radioiodine, by the implementation of ingestion control measures once the radioactive release has ceased.
   7. Iodine Thyroid Blocking should not normally be necessary in a radiological event involving detonation of a Radioactive Dispersal Device (RDD) due to the expected absence of radioiodine.
2. Responsibility
   1. The CMOH, in coordination with the PEOC and the local Medical Officer of Health shall direct the use of KI as described in the RHRP's Potassium Iodide Guidelines Annex.
   2. Reactor facilities (except Fermi 2), pursuant to their responsibilities to assist off-site authorities under the Regulations of Class I Facilities (Nuclear Safety and Control Act) and operating licence requirements, shall provide the necessary resources and support to provincial and municipal authorities to ensure that the ITB related requirements of the PNERP and municipal plans are completed.
   3. The MOHLTC shall procure, in advance, adequate quantities of Potassium Iodide (KI) pill, for use by local authorities of the Fermi 2 Detailed Planning Zone and Ingestion Planning Zone populations during a nuclear emergency.
   4. The MOHLTC shall provide support to local authorities for the Fermi 2 Detailed Planning Zone and Ingestion Planning Zone populations to ensure that the ITB related requirements of the PNERP and municipal plans are completed.
   5. Designated Municipalities and local authorities for the Fermi 2 Detailed Planning and Ingestion Planning Zones should perform periodic reviews of the local populations to assess the adequacy of their ITB distribution programs.
   6. Designated Municipalities for the Pickering, Darlington, Bruce and CRL reactor facilities, and local authorities for the Fermi 2 Detailed Planning and Ingestion Planning Zones, shall detail in their plans the means by which the availability of KI pills is facilitated for any resident of the Detailed Planning and Ingestion Planning Zones, including sensitive populations who may wish to possess a supply in advance of an emergency. This shall include:
      • The pre-distribution of KI pills together with instructions on KI administration to Detailed Planning Zone residences, businesses, institutions and for emergency centres (Emergency Worker, Reception and Evacuation Centres).
      • The appropriate information and education related to the benefits, risks and usage instructions of KI pills.
   7. Other matters related to Iodine Thyroid Blocking (ITB) with stable iodine (KI), including the provision of guidance and advice to health stakeholders and local organizations, are detailed in the RHRP's Potassium Iodide Guidelines Annex.

6.5.3 Evacuation

1. General
   1. Evacuation is the displacement of people from their homes for a period of approximately one week and would be undertaken during the early or intermediate phase to avoid or reduce short-term exposure to the plume or deposited radiation.
   2. Evacuation should be directed in areas where the projected or actual dose is expected to equal or exceed the evacuation generic criteria (Annex E, Appendix 1) or OILs (Annex E, Appendix 2).
   3. In the off-site area immediately adjacent to the source of radiation, evacuation may be the best protective action unless:
      • persons are unable to safely evacuate (e.g., vulnerable persons due to health issues)
      • conditions exist which make the evacuation hazardous (e.g., inclement weather, road or transportation issues, consequences resulting from a natural hazard)

        In such cases, sheltering-in-place may be more appropriate followed by evacuation once the release has ceased.

   4. Evacuation is most effective at limiting exposures when completed prior to the radioactive release.
   5. When evacuation is implemented during a radioactive release, radiation exposure could be increased. Therefore, if the release duration is known to be short, sheltering-in-place may be directed, to be followed by evacuation after the release.
   6. Evacuation can provide protection against exposure to radioactive groundshine, once the radioactive release has ceased where sheltering-in-place is not a viable option.
   7. Evacuation of the affected population should be directed when the projected or actual dose is expected to equal or exceed the Protective Action or Operational Intervention Levels respectively.
   8. Evacuation of the affected population should be considered for those areas where sheltering-in-place is expected to be required for more than 24 hours.
   9. Designated Municipalities and provincial institutions providing essential services (including facilities such as water treatment plants, hospitals and long-term care and nursing homes) shall develop plans for, and identify pre-designated special groups who cannot evacuate in the event of a nuclear emergency.
2. Responsibility
   1. The PEOC Commander shall direct evacuations as appropriate in consultation with the affected Designated Municipalities where time permits.
   2. The evacuation of the affected public should be facilitated by the planning and preparedness undertaken in advance, including:
      • transportation management (e.g., Ministry of Transportation)
      • reception and evacuation centres (e.g., Designated Municipalities)
      • long-term housing (e.g., multi-ministry and multi-jurisdictional planning group)
      • health issues (led by the Local Public Health Units and Medical Officers of Health in conjunction with the MOHLTC, Local health Integration Networks (LHINs) and Paramedic Services)
   3. Evacuation shall be directed using emergency bulletins issued by the PEOC Commander to the affected public (Section 7.3.2).

6.5.4 Sheltering-In-Place

1. General
   1. Sheltering-in-place directs people to remain indoors for a relatively short period of time and is generally undertaken during the early or intermediate response phases
   2. Sheltering-in-place should be directed in areas where the projected or actual dose is expected to equal or exceed the sheltering generic criteria (Annex E, Appendix 1) or OILs (Annex E, Appendix 2).
   3. The PEOC Commander and CMOH should normally consider directing sheltering-in-place together with a direction for Iodine Thyroid Blocking to provide maximum protection. However, exceptions may apply in cases where:
      • Analysis of reactor facility plant data definitively indicates that iodine does not pose a hazard.
      • The hazard from iodine is through the ingestion pathway for which ingestion control mechanisms are the appropriate protective action strategy.
   4. Sheltering-in-place is considered a very temporary measure, normally limited to a maximum of 2 days.
   5. Sheltering-in-place can be an appropriate interim measure in areas where a release (resulting from a nuclear accident or a radiological dispersion device) is either expected imminently or is ongoing.
   6. Sheltering-in-place may be a preferable alternative to evacuation where circumstances prevent a safe and efficient evacuation:
      • severe weather or environmental hazards
      • uncertain contamination or groundshine levels
      • vulnerable populations (e.g. hospitals, long-term care homes, etc.) for whom evacuation poses greater risks than that of the hazard itself
      • essential services staffing requirements
      • transportation impediments
   7. Large structures (e.g. shopping centres, schools, churches, commercial buildings, etc.) with high-density walls (e.g. concrete), generally provides greater radiation protection for sheltering-in-place than do small structures such as wooden single-family dwellings. Additionally, it is recommended to shelter in the basement or on middle floors, away from the walls or roof, of a multi-storey building.
2. Responsibility
   1. The PEOC Commander, shall direct sheltering-in-place as appropriate, in consultation with the affected Designated Municipalities where time permits.
   2. Sheltering-in-place shall be directed through emergency bulletins (Section 7.3.2) issued by the PEOC Commander to the affected public.

 

6.5.5 Temporary Relocation

1. General
   1. Temporary relocation is undertaken post-release, during the intermediate response phase, based on actual measured contamination levels.
   2. Temporary relocation is the displacement of people from their homes for a period beyond one week and up to one year to avoid chronic exposure to radiation, usually from ground contamination. Beyond one-year, permanent resettlement must be considered.
   3. Temporary relocation can be directed as a subsequent measure to evacuation, or sheltering-in-place, or as a separate measure.
   4. The need for temporary relocation is determined following analysis of environmental radiation monitoring results and assessment against Operational Intervention Levels (OILs; Annex E, Appendix 2).
   5. The PEOC should consider socioeconomic factors before recommending temporary relocation as the potential impacts of this action may not be justified in areas where the OIL for relocation is minimally exceeded.
2. Responsibility
   1. The PEOC Commander, shall direct temporary relocation as appropriate, in consultation with the affected Designated Municipalities and Designated Host Municipalities.
   2. Temporary relocation shall be directed through emergency bulletins (Section 7.3.2) issued by the PEOC Commander to the affected public.
   3. Relocation activities of the affected public should consider the planning and preparedness undertaken in advance, including:
      • transportation management (e.g., Ministry of Transportation)
      • reception and evacuation centres (e.g., Designated Municipalities)
      • long-term housing (e.g., multi-ministry and multi-jurisdictional planning group)
      • health issues (led by the Local Public Health Units and Medical Officers of Health in conjunction with the MOHLTC, Local health Integration Networks (LHINs) and Paramedic Services)

6.6 Protective Measures for Ingestion Control

6.6.1 Protective measures for ingestion control may include:

1. milk control
2. water control
3. pasture control
4. produce and crop control
5. livestock control
6. foodstuff control
7. land control[*]
8. environmental decontamination *

[*] Normally applicable only to the recovery phase.

6.6.2 The strategy for implementing ingestion control measures during a nuclear or radiological emergency should consider the following:

1. During the early phase, ingestion control measures may be directed as a precautionary measure (Section 6.4). The Detailed Planning Zone or larger area may be applicable for nuclear emergencies.
2. At the end of the early phase (or beginning of the intermediate phase), initiate environmental radiation and assurance monitoring (Section 7.6) within the entire Ingestion Planning Zone.
3. The PEOC Scientific Section Chief shall recommend the application, revision and rescinding of ingestion control measures as appropriate to the Command Section, based on their analysis of monitoring results from the environmental radiation and assurance monitoring field team.
4. Continue environmental radiation and assurance monitoring during the intermediate phase and through to the recovery phase to guide recovery decision-making.

6.6.3 The PEOC Commander, shall direct ingestion control measures as appropriate, in consultation with the affected Designated Municipalities where time permits.

6.6.4 Ingestion control measures shall be directed using emergency bulletins issued by the PEOC Commander to the affected public (Section 7.3.2).

6.7 Protective Action Decision-Making for Radiological Emergencies

6.7.1 Protective measures may have been implemented by first responders early in the event, before reliable radiological information was available (reference: PNERP Implementing Plan for Other Radiological Emergencies).

6.7.2 Once environmental monitoring teams are activated and data is received and analyzed, these protective measures can be adjusted or new ones directed, based on operational, technical (e.g. monitoring data applied against OILs, (Annex E, Appendix 2)) and public policy considerations.

6.7.3 The PNERP Implementing Plan for Other Radiological Emergencies provides more detail on radiological emergency response phases. The nuclear emergency phases outlined in Section 5.9 above may not be applicable due to the variability of radiological emergencies.

6.8 Additional Measures to Protect the Public

6.8.1 The PEOC Commander may recommend other, practical dose reduction measures to the public. Such measures may be implemented in combination with the measures described above or, may simply be recommended to provide an additional level of protection against possible radionuclides present in the air or on the ground but which do not meet the generic criteria or OILs. Such measures include:

1. Respiratory protection, such as covering of the nose and mouth with available material that can filter particulates when present in the air.
2. Self-decontamination, including removing and bagging contaminated clothing, showering, and decontaminating surfaces of critical areas and objects.
3. Staying indoors to the extent that it is practical, e.g. only conducting outdoor tasks when necessary (e.g. seeking medical attention, buying foodstuff and necessities).

6.8.2 Detailed advice regarding these measures shall be developed and implemented in both the preparedness stage through public awareness and education (Annex C) as well as for the emergency phase through the emergency bulletin process (Section 7.3.2).

6.9 Optimization of Protective Action Strategies

6.9.1 General

1. A system of optimization should be used to ensure that the most appropriate protective action strategy is implemented throughout all phases of an emergency.
2. Optimization extends beyond implementation of a protective action strategy to ensure that radiation doses are prevented or minimized when compared to intervention levels. When applied, optimization requires that the overall benefit of the strategy must be assessed to ensure that a suite of protective measures results in more benefit than harm. For example, the dose reduction achieved by relocating a large segment of the population may be of significance in absolute terms, however the relocation may result in significant psychosocial and economic disruptions without an associated observable reduction in expected latent cancers. In this example, the imposition of relocation as the protective action strategy may have a negative net benefit, and should be reconsidered.
3. Optimization becomes increasingly important as the emergency progresses and the protective action strategy should be reassessed as more information becomes available.

Table 6.1: Protective and Precautionary Measures