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Independent Environmental Monitoring Program: Darlington nuclear generating site

Site name Darlington Nuclear Generating Site
Licensee Ontario Power Generation (OPG)
Facility names Darlington Nuclear Generating Station and Darlington Waste Management Facility
Facility location On the north shore of Lake Ontario, in the Municipality of Clarington, Ontario
Land Acknowledgement The CNSC acknowledges that the Darlington Nuclear Generating Site is located within the traditional territory of the Wendat, Anishinabek Nation, and the territory covered by Williams Treaties First Nations.
Facility description OPG operates four 881-megawatt CANDU reactors, a tritium removal facility, and a waste management facility.
Environmental Protection Requirements In accordance with regulatory requirements under the Nuclear Safety and Control Act, all licensees must maintain a comprehensive environmental protection program to monitor and control nuclear and hazardous substances released from the facilities they own and operate. As part of every licensee’s environmental protection program, concentrations of contaminants in the environment must be determined and the potential exposure routes to the public must be assessed and mitigated. 

Our IEMP results from 2023, 2021, 2017, 2015 and 2014 are consistent with the results submitted by OPG, supporting our assessment that the licensee’s environmental protection program is effective. The results add to the body of evidence that people and the environment in the vicinity of the Darlington nuclear generating site are protected and that there are no anticipated health impacts from the operation of the facilities on the site.

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Darlington nuclear generating site

1 The < symbol indicates that a result is below the provided laboratory analytical detection limit.

2 N/A – not available

3 For radiological parameters (expressed as Bq/L, Bq/kg or Bq/m3) where no federal or provincial guidelines exist, our screening levels were established based on conservative assumptions using CSA standard N288.1-14, Guidelines for Calculating Derived Release Limits for Radioactive Material in Airborne and Liquid Effluents for Normal Operation of Nuclear Facilities. The screening level for a particular radionuclide in a particular medium (e.g., water, air, food) represents the activity concentration that would result in a dose of 0.1 mSv/year (millisieverts per year), a dose at which no impacts on human health are expected. For more information, please refer to the IEMP technical information sheet.

4 Tritiated water (HTO) is a radioactive form of water where the usual hydrogen atoms in water (H2O) are replaced with tritium. Elemental tritium (HT) refers to the radioactive form of hydrogen gas. Organically bound tritium (OBT) is tritium that is bound to an organic molecule, such as a carbohydrate, fat, or protein.

5 For water samples, the results for non-radiological parameters are compared to Canadian Council of Ministers of the Environment (CCME) Canadian Water Quality Guidelines for the Protection of Aquatic Life. Where no CCME guidelines exist, Health Canada’s Guidelines for Canadian Drinking Water Quality are used.

2023 results

The 2023 IEMP sampling plan for the Darlington nuclear generating site focused on radioactive substances. A site-specific sampling plan was developed based on the licensee’s approved environmental monitoring program and our regulatory experience with the site. We endeavour to incorporate traditional Indigenous land use, values and knowledge by engaging with Indigenous Nations and communities on the sampling plan. More information on this engagement is provided in the “Indigenous Nations and communities’ participation” section.

In September 2023, we collected air, water, soil, sediment, sand, vegetation and wild rice (nonedible leafy portion) samples in publicly accessible areas outside the facility perimeter.

The levels of radioactivity measured in air, soil, sediment, water and vegetation were below available guidelines and our own screening levels. Our screening levels are based on conservative assumptions about the exposure that would result in a dose of 0.1 mSv per year (one-tenth of the regulatory public dose limit of 1 mSv per year).

2021 Results

The 2021 IEMP sampling plan for the Darlington Nuclear Generating Site focused on radioactive and hazardous contaminants. A site-specific sampling plan was developed based on the licensee’s approved environmental monitoring program and our regulatory experience with the site. We endeavour to incorporate traditional Indigenous land use, values, and knowledge by engaging with Indigenous Nations and communities on the sampling plan. More information on this engagement is provided in the “Indigenous Nations and Communities’ Participation” section.

In August 2021, we collected air, water, soil, sand, vegetation, and local food samples in publicly accessible areas outside the facility perimeter.

The levels of radioactivity and hazardous substances measured in air, water, soil, sand, vegetation, and local food samples were below available guidelines and our own screening levels. Our screening levels are based on conservative assumptions about the exposure that would result in a dose of 0.1 mSv per year (1/10 of the regulatory public dose limit of 1 mSv per year). Measurements conducted through the IEMP to date have consistently found levels of radioactivity in the environment to be low, and well within the range of natural background radiation levels. As a result, no effects on human health are expected.

2014, 2015, and 2017 Results

The 2017 IEMP sampling plan for the Darlington site focused on nuclear and hazardous contaminants. A site-specific sampling plan was developed based on OPG's approved environmental monitoring program, CSA Group standards and the CNSC's regulatory experience with the site. In 2017, samples were collected in publicly accessible areas outside the Darlington site perimeter and included water, soil and beach sand, air, vegetation, and foods such as meat, fruits, vegetables and milk from local farms. View detailed sampling data.

The radiological and non-radiological analysis in air, water, sand, soil, vegetation, as well as samples of food, was below guidelines and CNSC screening levels. CNSC screening levels are based on conservative assumptions about the exposure that would result in a dose of 0.1 mSv/year, which represents one-tenth of the CNSC's public dose limit of 1 mSv/year. No health impacts are expected at this dose level.

2021 Indigenous Nations and communities’ participation

We have made it a priority to ensure that IEMP sampling reflects Indigenous traditional knowledge, land use, and values where possible. In addition to routine IEMP sampling activities, we seek input from potentially interested Indigenous Nations and communities on our IEMP sampling plans.

In advance of the 2021 IEMP sampling campaign at Darlington Nuclear Generating Site, notification emails were sent to potentially interested Indigenous Nations and communities to notify them of the sampling campaign and to seek input on the sampling plan. We invited suggestions for species of interest, valued components, and potential sampling locations where traditional practices and activities may take place.

Curve Lake First Nation (CLFN) joined us to participate in the sampling for a day. Having CLFN representatives participate in the sampling promotes a better understanding of sampling methods and locations and improves input into future sampling in terms of CFLN species of interest, valued components, and potential sampling locations.

We will continue to engage with interested Indigenous Nations and communities to ensure that IEMP sampling incorporates Indigenous knowledge in future campaigns.

View detailed sampling data.

2023 Indigenous Nations and communities’ participation

We have made it a priority to ensure that IEMP sampling reflects Indigenous traditional knowledge, land use and values where possible. In addition to routine IEMP sampling activities, we seek input from local Indigenous Nations and communities on IEMP sampling plans. In advance of the 2023 IEMP sampling campaign around the Darlington nuclear generating site, CNSC staff notified Indigenous Nations and communities near the facility of the planned sampling campaign, sought their input on the sampling plan and invited them to join CNSC staff in the field for sampling activities.

Mississaugas of Scugog Island First Nation

The Mississaugas of Scugog Island First Nation (MSIFN) reviewed the sampling plan in early 2023 and provided comments on species and locations of importance. CNSC staff considered MSIFN’s comments on the IEMP sampling plan; however, the specific species and locations could not be incorporated as they were within the fenceline, which is beyond the scope of the program. Three representatives from MSIFN joined the sampling team in the field in September 2023 to collect water, vegetation and soil samples. CNSC staff and the MSIFN representatives discussed the IEMP and walked through techniques for sampling air, water and soil, as well as packaging and chain of custody procedures.

Curve Lake First Nation and Hiawatha First Nation

Representatives from Curve Lake First Nation (CLFN) and Hiawatha First Nation (HFN) joined the CNSC field team to collect samples. CNSC staff started by explaining the program and the chain of custody procedures for the collected samples. CNSC staff then walked CLFN and HFN representatives through the air sampling process and equipment. The CLFN and HFN representatives assisted in the collection of water, vegetation, sand and soil samples. During the sampling campaign, CLFN and HFN representatives requested that CNSC staff test manoomin (wild rice) harvested from Chemong Lake, east of CLFN, and shared the spiritual and cultural importance of manoomin to their communities. The CNSC field team prepared a sample kit and walked participants through the instructions on how to get the manoomin sample packaged and sent to the lab. CNSC staff note that the manoomin sample was not from the edible portion of the plant due to the timing of when it was harvested. CLFN and HFN expressed their appreciation for the opportunity to sample manoomin, and HFN is looking forward to bringing CNSC staff to collect manoomin samples near their community in the future. The CNSC is committed to working with CLFN and HFN to ensure that the IEMP reflects their Indigenous traditional knowledge, land use and values where possible.

Focus on health

We review the results of public health reports and data, international publications, and at times conduct our own health studies to provide further independent verification that the health of people in and around the Darlington nuclear generating site is protected.

The Durham Region Health Department (DRHD) and Cancer Care Ontario monitor the health of populations around the Darlington nuclear generating site. Disease rates are compared to the rates in other similar populations (or larger reference populations such as Ontario) to detect any potential health outcomes that may be of concern.

Similar to the population of Ontario, the cancer burden in Durham Region (DR) is primarily breast cancer (females), prostate cancer (males), lung cancer and colorectal cancer. Cancer incidence and mortality trends are typically considered over long periods of time. As an example, looking at the recent reported period of 2014 to 2018, for both sexes and all cancer types combined, DR had incidence rates higher than the Ontario average, but cancer deaths similar to those of Ontario. For the same reported period, compared to the Ontario average, DR had higher incidence rates of melanoma, prostate (males), lung and thyroid cancer, whereas rates of non-Hodgkin lymphoma and colorectal cancer were lower. While some incidence rates are higher in DR than in Ontario, they are comparable to other geographically/demographically similar regions without nuclear sites (e.g., Niagara and Ottawa regions). Incidence rates of different cancer types often vary by region and are influenced by many factors, including socio-demographics and lifestyle (e.g., overdue cancer screening, high alcohol intake, smoking and excess body weight / obesity).

Health status data for Indigenous people are not reported separately by the DRHD.

It is recognized that the opportunity to be healthy is not the same for everyone, and is affected by personal, social, economic and environmental factors. The DRHD supports the reduction of health inequalities across DR and offers a wide range of health-enhancing programs.

A recent and comprehensive CNSC study on the health of people living near nuclear power plants found that all cancers for all age groups in individuals living near those facilities were similar to the rest of Ontario. In particular, there was no evidence of increases of childhood leukemia. These findings are consistent with research studies conducted around nuclear power plants in other countries (i.e., the United Kingdom, France, Switzerland and Finland). The body of evidence demonstrates that people who live near nuclear power plants, such as the Darlington nuclear generating site, are as healthy as the rest of the general Canadian population.

Based on current levels of radionuclides in the environment; exposures to people living in the area; the current scientific knowledge about the sources, effects and risks of ionizing radiation; and relevant local and provincial health data, we have not observed and do not expect to observe any adverse health outcomes related to the presence of the Darlington nuclear generating site. For further information, access the CNSC Health Studies page.

If you would like more general health information and data for your community, please visit the following websites:

Durham Region Public Health

Durham Region Public Health – Health Neighbourhoods

Cancer Care Ontario – Statistical Reports

Cancer Care Ontario – Ontario Cancer Profiles

Conclusions

Our IEMP results from 2023, 2021, 2017, 2015 and 2014 are consistent with the results submitted by OPG, supporting our assessment that the licensee’s environmental protection program is effective. The results add to the body of evidence that people and the environment in the vicinity of the Darlington nuclear generating site are protected and that there are no anticipated health impacts from the operation of the facilities on the site. 

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