Annex L PNERP planning basis background

(Reference: Paragraph 1.3.5)

1.0 General

The PNERP is regularly reviewed relative to changing international best practices and lessons learned from actual events. As such, the 2017 update was motivated and informed by the following:

1. The release of new standards and guidance documents, including the Canadian Standards Association's (CSA) N1600 General Requirements for Nuclear Emergency Management Programs, International Atomic Energy Agency's (IAEA) General Safety Requirements (GSR) Part 7 and the Health Canada Canadian Guidelines for Protective Actions During a Nuclear Emergency (DRAFT 2016).
2. Lessons learned from three full scale nuclear emergency response exercises held in Ontario (Exercise Huron Challenge 2012, Exercise Unified Response 2014 and Exercise Huron Resolve 2016).
3. Analysis and lessons learned from the Fukushima Daiichi nuclear disaster in March 2011 in Japan, including the Levels and Effects of Radiation Exposure Due to the Nuclear Accident after the 2011 Great East-Japan Earthquake and Tsunami report published by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) in 2013.
4. The Canadian Nuclear Safety Commission's (CNSC) Post-Fukushima Action Plan recommendation that provincial authorities undertake a review of the accident scenarios on which their off-site plans are based, (i.e., the planning basis) for the purposes of off-site arrangements.
5. The discussion paper Provincial Nuclear Emergency Response Plan, Planning Basis Review and Recommendations released by OFMEM in May 2017.

The remainder of this Annex provides a summary of the principles, assessments and conclusions reached by this discussion paper. For a more fulsome overview of the planning basis determination, the discussion paper itself should be consulted.

2.0 Principles

In the May 2017 PNERP Planning Basis Discussion Paper, the Office of the Fire Marshal and Emergency Management (OFMEM) analyzed historical and contemporary reports, studies and technical analyses. Severe accident assessments were selected in collaboration with key stakeholders, some of whom also provided assistance in the form of modelling to determine dose versus distance data^{footnote 20[20]}.

The planning basis determination was undertaken in alignment with internationally accepted principles, including:

• Emergency plans should aim to prevent deterministic effects and minimize the stochastic effects which possibly could result from severe, low probability nuclear accidents^{footnote 21[21]}.
• While emergency plans should be based on a wide range of accidents, the amount of detailed planning should decrease as the probability of the accidents occurrence decreases.^{footnote 22[22]}

The planning basis determination has been elucidated in terms of the emergency planning zones, including the new Contingency Planning Zone, which have been incorporated into this PNERP Master Plan. These zones were adopted to better align the Plan with the principles and requirements of national and international standards (CSA N1600 and IAEA GSR 7), and each is defined in terms of the level and extent of planning and preparedness required to prepare for a nuclear emergency:

1. Automatic Action Zone (AAZ): A pre-designated area immediately surrounding a reactor facility where pre-planned protective actions would be implemented by default on the basis of reactor facility conditions with the aim of preventing or reducing the occurrence of severe deterministic effects.
2. Detailed Planning Zone (DPZ): A pre-designated area surrounding a reactor facility, incorporating the Automatic Action Zone, where pre-planned protective actions are implemented as needed on the basis of reactor facility conditions, dose modelling, and environmental monitoring, with the aim of preventing or reducing the occurrence of stochastic effects.
3. Contingency Planning Zone (CPZ): A pre-designated area surrounding a reactor facility, beyond the Detailed Planning Zone, where contingency planning and arrangements are made in advance, so that during a nuclear emergency, protective actions can be extended beyond the Detailed Planning Zone as required to reduce potential for exposure.
4. Ingestion Planning Zone (IPZ): A pre-designated area surrounding a reactor facility where plans or arrangements are made to:
   1. protect the food chain
   2. protect drinking water supplies
   3. restrict consumption and distribution of potentially contaminated produce, wild-grown products^{footnote 23[23]}, milk from grazing animals, rainwater, animal feed
   4. restrict distribution of non-food commodities until further assessments

The discussion paper was also based on the concept that while planning and preparedness measures are required to facilitate the implementation of exposure control measures in the AAZ and DPZ, detailed planning is, in fact, not required in order to undertake the implementation of all exposure control measures. For example:

• Sheltering can be implemented through existing public alerting mechanisms, advising the population to stay indoors.
• ITB requires an effective distribution program based on population data and accident assessment thyroid dose results.

In contrast, the implementation of evacuations must include detailed planning and preparedness arrangements for:

• Transportation and traffic
• Monitoring and decontamination
• Short-term accommodation
• Long-term accommodation
• Health, economic, trade, education, psychosocial, etc. issues

As such, the Detailed Planning Zones for the CANDU stations are delineated to accommodate the projected effective dose at which the evacuation generic criterion is reached. And, further to this concept, the sheltering and ITB distances were therefore not the defining point for determination of the DPZ.

3.0 BDBA Accident Assessment and Conclusions: CANDU Reactors

The Canadian Nuclear Safety Commission (CNSC) provided OFMEM with source term information based on a Station Blackout (SBO) scenario with three (3) releases as detailed in OPG's Darlington NGS Level 2 Probabilistic Safety Assessment (PSA) Report (from the 2012 refurbishment project). Health Canada and Environment and Climate Change Canada (ECCC) staff provided assistance in the form of dose modelling using the Accident Reporting and Guidance Operational System (ARGOS) application.

The CNSC advised OFMEM that it is reasonable to assume that the Operator could stop the accident to prevent the second and third releases and therefore only the first release of the SBO accident was considered. The first release is an International Nuclear Events Scale (INES) Level 7 event.

While the severe accident assessment involves accident progressions that are considered to be highly unlikely, it should also be noted that the Level 2 Darlington PSA was performed prior to the Fukushima event. Consequently, the accident progression does not take into account the post-Fukushima implementation of such station improvements as emergency mitigating equipment, which would halt the accident progression.

The precaution offered by Health Canada in the report should be noted as it accurately reflects the basic principles integral to this discussion paper:

When interpreting the results, it should be acknowledged that the scenarios are hypothetical and that there are inherent uncertainties associated with this type of predictive modelling as well as specific limitations associated with the approach used. While these results may provide some useful information, they should not serve as the sole source of information for nuclear emergency preparedness activities.^{footnote 24[24]}

3.1 Protective Measures for Inhalation (Plume)

The Mean and MaxIMUM doses with distance for protective measures against inhalation were generated from 9 individual runs using the Modèle Lagrangien de Dispersion de Particules (MLDP) modelling and detailed weather patterns for each day in the period between July 10 and July 18, 2016.

Mean dose values were generated by averaging all of the doses at each radial distance. MaxIMUM dose values represent the highest dose reported at each radial distance from the nuclear power plant. These doses are measured against Health Canada's "Dosimetric Criteria for Nuclear Emergency Planning and Response (Draft 2017)" Generic Criteria for evacuation (100 mSv) which aligns with the IAEA GSG-2 Guidance for evacuation and sheltering).

The doses are reproduced below taking into account the assumptions, pursuant to CSA N288.2-14^{footnote 25[25]} that a sheltering dose reduction factor be applied and that the representative individual for emergency planning purposes should be an adult.

3.1.1 Evacuation Criteria using Risø Mesoscale PUFF (RIMPUFF^{footnote 26[26]}) Modelling

3.1.2 Evacuation Criteria using Modèle Lagrangien de Dispersion de Particules (MLDP^{footnote 27[27]}) Modelling

3.1.3 Iodine Thyroid Blocking using MLDP Modelling

3.2 Protective Measures for Ingestion using MLDP Modelling

3.3 Conclusions for CANDU Reactors

1. Evacuation:

   Evacuations are not required beyond the Detailed Planning Zone boundary.

2. Iodine Thyroid Blocking:

   Based on the 50 mSv intervention level and the N288.2-14 standard that adult doses be considered for emergency planning purposes^{footnote 28[28]}:

   • The Mean dose for Adults indicates that ITB may be required within the Detailed Planning Zone.
   • The Max dose for Adults indicates that ITB may be required out to a distance of 33 km (within the Ingestion Planning Zone) in the direction of plume passage.
3. Ingestion Control:

   Based on Health Canada guidance for ingestion control purposes^{footnote 29[29]}:

   • The Mean results indicate that food restrictions may be required in all directions from the facility up to distances of approximately 30km. Therefore, the 50km radius for the Ingestion Planning Zone is generally appropriate for detailed ingestion control planning.
   • The Max results indicate that food restrictions may be required at distances up to approximately 70 km, in the direction of plume passage and would be dependent on the type of food being produced.

4. Critical in the consideration of the nuclear emergency planning zones is the understanding that limitations to resources and standardized assumptions are being applied for PLANNING purposes to optimize protective action planning for low probability severe nuclear accidents. However, ACTUAL EMERGENCY RESPONSE for all scales of nuclear accidents will be undertaken with the necessary resources AND in consideration of the most vulnerable populations, to ensure the province's aim of protecting public health and safety and the environment.

   And, on this basis, the PNERP has been developed to ensure that the appropriate organizational structures, linkages and processes are in place to enable a scalable response regardless of the severity of the nuclear accident.

4.0 Accident Assessment and Conclusions: Chalk River Laboratories (CRL)

4.1 Two technical studies were examined to provide recommendations for the CRL planning basis:

1. Analysis Report for KI Pill Intervention Planning for CRL, Candesco (2016)
2. International Safety Research Inc. (ISR) Independent Study (2004)

4.2 Analysis Report for KI Pill Intervention Planning for CRL

CRL undertook an assessment to determine the KI pill pre-stocking requirement beyond its Primary Zone (i.e., Detailed Planning Zone) boundary, as directed by CNSC REGDOC 2.10.1.

The Candesco report describes an assessment of Iodine releases that might result from an 8E-7 beyond design basis accident (BDBA) to determine the distance from the CRL site within which Iodine Thyroid Blocking (ITB) would be justified.

The Candesco report determined that, for the BDBA analyzed, the projected thyroid dose for an exposed individual at the 9 km Primary Zone boundary would be 0.81 mSv, which is 60 times below the Thyroid Blocking Protective Action Level (PAL) of 50 mSv. When considering even lower probability BDBAs, the projected thyroid dose remains substantially less (2-3 times) than the 50 mSv Thyroid Blocking PAL. It is therefore not anticipated that KI ingestion would be required for the public, even in the event of a severe nuclear emergency at CRL.

CRL indicated that CNSC staff has agreed that the BDBA scenarios used for the purposes of this study were sufficiently severe.

4.3 ISR Study (2004)

A re-examination of the 2004 ISR independent study was undertaken to ensure consistency in application of emergency management best practice principles.

The results of the ISR study found that under severe accident conditions, only the sheltering protective action would be required in the Primary Zone (i.e., Detailed Planning Zone) and, using the 2009 PNERP PALs, that this measure would likely be limited to the 8 km radius from the CRL stack (using the lower Sheltering PAL). Evacuations would be limited to a radius of 3 km (using the lower Evacuation PAL) which falls within the boundaries of the CRL 6 km Exclusion Zone.

During the PNERP review for the 2009 PNERP Master Plan and 2011 Implementing Plan for CRL, the decision was made to delineate a 9 km Primary Zone on the following basis:

• It maintains a degree of consistency with the other PNERP nuclear areas and a high level of public safety.
• It results in a minimal reduction from the previous 10 kilometre Primary Zone requirement.
• Although it would not need to be implemented in a condensed timeframe as for the other sites, a potential for evacuation persists if sheltering is required for longer than 1-2 days.

Application of the draft Health Canada's Dosimetric Criteria for Nuclear Emergency Planning and Response (Draft 2017) would result in an evacuation radius of less than 2 km and a sheltering radius of less than 3 kilometres, both of which are well within the exclusion area of the CRL facility.

4.4 Conclusions for CRL

1. The CRL NRU reactor is scheduled for shutdown on March 31, 2018, after which an assessment will determine the risks the shutdown reactor may represent to the surrounding offsite population.
2. The planning basis for the NRU reactor at CRL has historically been based on the areas defined for CANDU reactors. In 2009, the Primary Zone was reduced from 10 km to 9 km. While no requirement for evacuation in this area was predicted, the Primary Zone delineation was essentially maintained (although diminished), based solely on the need for sheltering.
3. Based on the 2004 and 2016 severe accident studies and using the Health Canada Guidelines, only the sheltering protective action would be required offsite, i.e., beyond the CRL Exclusion Zone.
4. Although none of the accident scenarios (including severe accidents) associated with this facility result in the need for offsite evacuations, thereby removing the need for detailed planning, the planning zones for the CRL National Research Universal (NRU) reactor will remain as identified in the 2011 PNERP Implementing Plan for CRL.

5.0 Conclusions: Fermi 2

5.1 The Ontario Primary Zone (i.e., Detailed Planning Zone) for the Fermi 2 reactor facility in Michigan varies in extent from 16 to 23 kilometres in radius. This delineation dates back to the early 1980's and while the exact rationale for its extent is not known, it did have a basis in the pre-amalgamation involvement of three separate municipalities – the Towns of Amherstburg, Anderdon and Malden. The U.S. equivalent of Ontario's Primary Zone, the Emergency Planning Zone, is a standard 10 miles (16 kilometres) for all U.S. based nuclear facilities.

5.2 Planning Zones for Fermi 2

As with the CRL facility (Section 4.0 above), the planning zones associated with the Fermi 2 nuclear generating station in Michigan (across the Detroit River from Ontario) differs from the Bruce, Pickering and Darlington nuclear generating stations due to different technologies.

The revised PNERP will reflect the American nuclear regulatory agency's (U.S. NRC) requirements for planning zones. Specifically, the following PNERP Planning zones will be delineated for the Fermi 2 site:

1. No Automatic Action Zone (the area lies within a 3 km radius around the nuclear station).
2. The Detailed Planning Zone will be reduced to a radius of 16 km to align with the American standard (10 miles).
3. The Contingency Planning Zone distance will be determined during the Fermi 2 Implementing Plan development and consultation.
4. The Ingestion Planning Zone will be maintained at 80 km to align with the American standard (50 miles) for the Fermi 2 reactor technology.