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Environmental protection review report summary: Darlington Waste Management Facility

Environmental protection review (EPR) reports provide the findings from CNSC staff’s technical assessment of how effectively licensees are protecting human health and the environment in the communities in which they are operating. The summary that follows highlights key areas of interest from the EPR report for the Darlington Waste Management Facility (DWMF). It represents only some of the information presented in the full report.

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About the facility

The DWMF is owned by Ontario Power Generation (OPG) and is located in the Darlington Nuclear (DN) site in the Municipality of Clarington, Ontario, on the north shore of Lake Ontario. The facility lies within the traditional territory of the Wendat, Anishinabek Nation, and the territory covered by the Williams Treaties with the Michi Saagiig and Chippewa Nations. Under OPG’s current licence, the DWMF is authorized to operate the storage buildings (designed to house dry storage containers (DSCs) for used fuel bundles), a DSC processing building, and the Retube Waste Storage Building (RWSB).

About the report

The purpose of the report is to share CNSC staff’s findings from their review of OPG’s environmental protection measures and environmental compliance activities. This includes staff’s assessment of any possible environmental releases as part of normal operations and the risks that radiological or hazardous (non-radiological) substances pose to the environment and human health. The report draws on information provided by OPG and the CNSC’s technical assessments, including:

  • the results of OPG’s environmental monitoring, as reported in the annual compliance monitoring reports
  • OPG’s 2020 environmental risk assessment for the DN site
  • OPG’s 2021 preliminary decommissioning plan for the DWMF
  • the results of the CNSC’s Independent Environmental Monitoring Program (IEMP – see the IEMP web page on the DN site)
  • the results from other environmental monitoring programs and/or health studies (such as studies completed by other levels of government) in proximity to the DN site
  • OPG’s licence renewal application for the DWMF

Overall, CNSC staff found that OPG continues to implement and maintain effective environmental protection measures to adequately protect the environment and the health of people working in and living around the DN site. CNSC staff found that the potential risks to the environment from any of the releases observed between 2016 and 2021 are similar to natural background levels and that any health risk is similar to that experienced by the general public in other parts of Ontario.

Environmental monitoring

In the nuclear industry, any kind of contaminant emitted by a facility is called a release. This report looks at different types of releases and their possible impacts on the land, air and water in the area surrounding the DWMF, as well as any potential impact on human health.

Figure 1 illustrates how a release may reach the environment through what’s called exposure pathways. In the case of the DWMF, this graphic is a simplified representation of the DN site and different types of releases – such as emissions in the air or effluent in the water – and the human and ecological receptors that may interact with the releases. Releases from the DWMF are indistinguishable from, and significantly lower than, those from the neighbouring Darlington Nuclear Generating Station (DNGS). For this reason, emissions from the DWMF are considered a small fraction of the overall emissions and releases from the DN site.

Figure 1: The different potential exposure pathways a release from the DN site may use to reach the environment and humans

The pathways represented in the graphic may include the following components: atmospheric release, tritium vapour, crop ingestion, well water exposure, inhalation, resuspension and inhalation, inhalation and immersion in air, groundshine (ground-deposited contaminants), inhalation, shoreline exposure, immersion (water), wild food ingestion, aquatic food ingestion, ingestion by wildlife, uptake by aquatic organisms, crop and animal irrigation, and animal ingestion.

OPG must monitor its releases and measure them against pre-established limits. OPG then reports its results to the CNSC and other levels of government. The CNSC verifies this data by conducting reviews and inspections of OPG’s environmental protection programs, as well as by using mechanisms such as the IEMP.

CNSC’s monitoring

Under the IEMP, CNSC staff take samples, such as air, water, soil, sediment, vegetation, and some local food like meat or vegetables from public areas near nuclear facilities. These areas may include parks, farmland and beaches. The samples are then tested at the CNSC’s laboratory in Ottawa for contaminants related to each facility’s operations.

CNSC staff conducted IEMP sampling around the DN site in 2021, 2017, 2015 and 2014.

Laboratory specialists analyzed the samples in the CNSC’s laboratory. The levels of radiological and hazardous substances in all the samples measured in 2021 were below available guidelines and were similar to the range of results from the previous IEMP sampling campaigns at the DN site.

The CNSC’s IEMP web page on the DN site has more information, including detailed sampling results.

OPG’s monitoring

Air: Atmospheric releases

OPG controls and monitors airborne emissions that come from operations at the DWMF. At the facility, there is a small potential for airborne emissions resulting from DSC processing operations, such as welding and vacuum drying. To mitigate these releases, OPG uses a high efficiency particulate air (HEPA) air filtered active ventilation system, and the exhaust is monitored for radioactive particulates.

The monitoring results (table 1) show that air emissions of gross beta-gamma were consistently several orders of magnitude below release limits during the monitoring period. As a result, CNSC staff have found that OPG continues to provide adequate protection of people and the environment.

Table 1: Annual airborne releases from the DWMF in becquerels compared with applicable release limits (2016 to 2021)
Source Year Gross beta-gamma (Bq) (a) Licence limits [32] (Bq)
Stack 2016 2,849 6.70 x 1011
2017 16,983 6.70 x 1011
2018 12,739 6.70 x 1011
2019 2,812 6.06 x 1011
2020 5,069 6.06 x 1011
2021 2,516 6.06 x 1011

Water: Liquid releases

There are no liquid releases that result from operations of the DWMF. However, OPG routinely monitors stormwater releases and foundation drainage for tritium and gross gamma. The stormwater releases and foundation drainage are primarily influenced by air emissions from external facilities (such as tritium washout from the nearby DNGS).

The monitoring results (table 2) show that stormwater releases of tritium and gross gamma were well below release limits during the monitoring period. As a result, CNSC staff have found that OPG continues to provide adequate protection of people and the environment.

Table 2: Annual stormwater releases from the DWMF in becquerels per litre compared with applicable administrative limits (2016 to 2021)
Source Year Tritium (Bq/L) (a) Administrative limit (Bq/L) Gross gamma (Bq/L) (a) Administrative limit (Bq/L)
Stormwater 2016 652 1,850 8.55 37
2017 543 1,850 7.92 37
2018 474 1,850 7.41 37
2019 493 1,850 7.47 37
2020 443 1,850 7.60 37
2021 536 1,850 7.48 37

Human health

Monitoring doses

When ionizing radiation penetrates the human body or an object, it deposits energy. The energy absorbed from exposure to radiation is called a dose. Under the Radiation Protection Regulations, the maximum dose limit to a member of the public is 1 mSv (millisievert) or 1,000 μSv (microsieverts) per year. This is well below levels where any measurable health effect would occur.

To calculate the effective dose to people living near the site, OPG assessed the risk to representative persons who had the potential to be the most exposed to contaminants. These include urban residents in Oshawa/Courtice, Bowmanville, rural residents, and Indigenous Nations and communities. In general, representative persons may be exposed to contaminants through 4 primary routes: dermal (skin), inhalation, incidental ingestion (soil), and ingestion of food and water.

Between 2017 and 2021, the estimated annual radiological doses for the public near the DWMF remained at or below 0.8 μSv. These doses are several magnitudes lower than the regulatory annual dose limit for the public, indicating that radiological releases from the facility pose a negligible risk to human health (that is, potential risk to humans is similar to health outcomes in the general public).

Health studies

Reviewing and conducting health studies is an important component of ensuring that the health of people living near or working in nuclear facilities is protected. CNSC staff have considered the most recent international radiation epidemiology reports, the CNSC’s own information and scientific publications, as well as various community, provincial and national-level studies and reports when evaluating the health of populations living or working near the DN site or similar facilities.

Workers and the public are protected against radiation exposures from the DWMF and the DN site. The population and community health studies and reports indicate that common causes of death among the surrounding populations include ischemic heart disease, lung cancer, dementia and Alzheimer’s disease. Major health risk factors such as smoking, physical inactivity, excessive alcohol consumption, and poor diet may account for the occurrence of these diseases.

Based on the assessed exposure and health data, CNSC staff have not observed and do not expect to observe any adverse health outcomes attributable to the DWMF.

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