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Environmental protection review report summary: Rabbit Lake Operation

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 following summary highlights key areas of interest from the EPR report for the Rabbit Lake Operation. It represents only some of the information presented in the full report.

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About the facility

The Rabbit Lake Operation is located within Treaty 10 territory, the Homeland of the Métis, and is within the traditional territories of the Denesųłiné, Cree, and Métis peoples. The facility is owned by Cameco Corporation (Cameco) and is located within the Athabasca Basin of northern Saskatchewan, approximately 720 km north of Saskatoon. Under its current uranium mine licence, Cameco is authorized to mine and mill uranium at the Rabbit Lake Operation. In 2016, the facility was placed in a state of safe care and maintenance that has continued to date. Cameco has not informed CNSC staff of any plans to restart production at the Rabbit Lake Operation.

About the report

The following summary highlights key areas of interest from the EPR report for the Rabbit Lake Operation. It represents only some of the information presented in the full report.

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

  • the results of Cameco’s environmental monitoring, as reported in annual reports
  • Cameco’s 2015 human health and ecological risk assessment for the Rabbit Lake Operation
  • Cameco’s 2020 environmental risk assessment for the Rabbit Lake Operation
  • Cameco’s 2020 preliminary decommissioning plan for the Rabbit Lake Operation
  • plans for the CNSC’s Independent Environmental Monitoring Program (IEMP)
  • results from other environmental monitoring programs and/or health studies (such as those completed by other levels of government) in proximity to Cameco’s Rabbit Lake Operation

Overall, CNSC staff found that Cameco continues to implement and maintain effective environmental protection measures to adequately protect the environment and the health of people living in and around northern Saskatchewan. CNSC staff found that the potential risks to the environment from any of the releases from the Rabbit Lake Operation, observed between 2012 and 2022, are similar to the risks posed by natural background radiation levels. It was also found that any health risk is similar to that experienced by similar northern communities.

Environmental monitoring

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

Figure 1 illustrates how a release may reach the environment through what is called an exposure pathway. In the case of the Rabbit Lake Operation, this graphic is a simplified representation of the facility 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.

Figure 1: Different potential exposure pathways through which a release from the Rabbit Lake Operation may reach the environment and humans
Conceptual exposure pathways for atmospheric and aquatic releases to the environment from the Rabbit Lake Operation.

The potential pathways represented in the graphic may include the following components: atmospheric release, groundwater discharge to surface water, wind erosion, airborne exposure, uptake by sediment dwelling organisms, uptake by forage fish, uptake by predator fish, uptake by wildlife, and groundshine.

Cameco must monitor its releases and measure them against pre-established limits. It then reports its results to the CNSC and other levels of government. The CNSC verifies this data by conducting reviews and inspections of Cameco’s environmental protection programs.

CNSC’s monitoring

Under the IEMP, CNSC staff take samples – for example, of air, water, soil, sediment, vegetation, and local food like meat or vegetables – from public areas near nuclear facilities. For the uranium mines and mills in northern Saskatchewan, the IEMP sampling is conducted by a qualified contractor. The samples are then tested by a third-party laboratory for contaminants related to each facility's operations including radionuclides and hazardous substances.

In summer 2022, a qualified contractor, with the assistance of a CNSC staff member and a community land technician from the Ya’thi Néné Lands and Resources Office, conducted IEMP sampling around the Rabbit Lake Operation. As part of that sampling campaign, input from relevant Indigenous Nations and communities informed the sampling locations and the selection of samples, which included water, Labrador tea, blueberries and fish.

At the time of the EPR report’s publication, the IEMP results were not available. These results will be published on the CNSC’s IEMP web page once the CNSC’s analysis is complete.

Cameco’s monitoring

Atmospheric releases

Cameco controls and monitors airborne emissions from the Rabbit Lake Operation to the environment. Cameco monitors for both radiological and hazardous emissions. At the facility are various potential sources of airborne releases, including material handling of ore and waste rock, wind erosion of ore and waste rock, grading of unpaved roads, ventilation exhaust from the milling infrastructure, and fugitive sources of radon.

Since April 2016, the Rabbit Lake Operation has been in a state of care and maintenance. The sulphuric acid plant has been shut down since and there have been no releases to the environment (see table 1). CNSC staff have found that Cameco continues to provide adequate protection of people and the environment.

Table 1: Annual total airborne releases of sulphur dioxide from the Rabbit Lake Operation (2013–2021)
Parameter 2013 2014 2015 2016 2017 2018 2019 2020 2021
Sulphur dioxide (kg) 37,336 58,229 41,308 16,232 0 0 0 0 0

Liquid releases

Cameco routinely monitors and controls liquid effluent released from the Rabbit Lake Operation to the environment. The Rabbit Lake Operation mill process and effluent treatment systems receive contaminated water from various sources, remove dissolved metals and suspended solids, and subsequently discharge to the final effluent polishing system adjacent to the Rabbit Lake Operation for final treatment and discharge to Horseshoe Creek.

The monitoring results (see table 2) show that water releases (treated liquid effluent) were at levels well below release limits during the monitoring period. As a result, CNSC staff have found that Cameco’s treatment of liquid effluent is providing appropriate protection to people and the environment.

Table 2: Annual waterborne releases from the Rabbit Lake Operation compared with applicable release limits (2013–2021)
Parameter (a) Licence limit 2013 2014 2015 2016 2017 2018 2019 2020 2021
Arsenic (mg/L) 0.3 0.0055 0.0056 0.0040 0.0025 0.0010 0.0009 0.0009 0.0009 0.0012
Copper (mg/L) 0.3 0.0045 0.0040 0.0030 0.0013 0.0002 0.0003 0.0002 0.0002 0.0002
Lead (mg/L) 0.1 0.0001 0.0002 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
Nickel (mg/L) 0.5 0.0144 0.0184 0.0057 0.0038 0.0017 0.0015 0.0013 0.0013 0.0014
Zinc (mg/L) 0.5 0.0010 0.0010 0.0010 0.0010 0.0006 0.0006 0.0007 0.0005 0.0009
pH (b) 6.0 to 9.5 7.2 7.3 7.4 7.3 7.5 7.5 7.1 7.2 7.2
Radium-226 (Bq/L) 0.37 0.008 0.010 0.007 0.007 0.007 0.006 0.006 0.006 0.006
Total suspended solids (TSS) (mg/L) 15 2 2 2 2 1 1 1 1 1
Un-ionized ammonia (g) (mg/L) 0.5 0.01 (f) 0.01 (f) 0.02 0.01 0.01 0.01 0.01 0.01 0.01
Selenium (mg/L) 0.6 (c) 0.0052 0.0042 0.0042 0.0035 0.0024 0.0026 0.0023 0.0026 0.0025
Uranium (mg/L) 2.5 (d) 0.063 0.046 0.052 0.073 0.070 0.032 0.027 0.021 0.018
Molybdenum (mg/L) N/A (e) 0.324 0.282 0.268 0.273 0.139 0.180 0.159 0.184 0.213
  • (a) Results show the mean of the concentrations for each month in 1 year.
  • (b) The pH is taken from every discharge samples. It is not measured in monthly composite samples.
  • (c) This is the provincial limit that is not in the CNSC licence.
  • (d) This is the provincial limit that is not in the CNSC licence. As discussed in subsection 3.1.1 of the full report, in the absence of a CNSC licence limit for uranium, the CNSC uses the interim objective for uranium of 0.1 mg/L as a benchmark to demonstrate the application of the ALARA and BATEA principles.
  • (e) Refer to subsection 3.1.1 of the full report for an explanation of why no provincial or federal licence limits currently exist for molybdenum.
  • (f) The 2013 and 2014 un-ionized ammonia values are calculated using the measured temperature, field pH, and ammonia values.
  • (g) Un-ionized ammonia was added to the Metal and Diamond Mining Effluent Regulations in 2021.

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 CNSC’s regulations, the maximum dose limit to a member of the public is 1 millisievert (mSv) or 1000 microsieverts (µSv) 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, Cameco assessed the risk to representative persons who had the potential to be the most exposed to contaminants. A total of 6 human receptor groups were identified as being the most exposed for potential radiological and hazardous contaminant exposures. The groups included onsite and offsite workers and offsite residents.

Cameco also considered how a representative person located within or near the site could be exposed to potential radiological or hazardous substances, such as through breathing the air, being on the land, drinking and swimming in surface water, or eating plants, fish and wildlife near the facility.

The estimated annual radiological doses for the public near the Rabbit Lake Operation for the 2013–2022 period have remained below the regulatory annual dose limit for the public. This indicates that radiological releases from the Rabbit Lake Operation 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 and reports is an important component of ensuring that the health of people living near or working in nuclear facilities is protected. When evaluating the health of populations living or working near the Rabbit Lake Operation or similar facilities, CNSC staff consider 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.

Workers and the public are protected against radiation exposures from the Rabbit Lake Operation. The population and community health studies and reports indicate that the most common causes of death among the population of northern Saskatchewan are injuries, cancer (predominantly seen in people that are 50 years of age and older), circulatory diseases, and respitory diseases. Lung cancer rates are greater in northern Saskatchewan compared to the provincial average and thus, lung cancer is the most common cause of cancer death in Indigenous Nations communities in northern Saskatchewan.

To get a snapshot of the health of the population living near the Rabbit Lake Operation, CNSC staff looked at information and data from various sources. Based on exposure and health data, CNSC staff have not observed and do not expect to observe any adverse health outcomes to northern Saskatchewan communities or workers due to the presence of the Rabbit Lake Operation.

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