Summary of environmental protection review report: McArthur River Operation

Environmental protection review (EPR) reports provide CNSC staff’s evaluation of how effectively licensees are protecting human health and the environment in the communities in which they operate. The following summary highlights key areas of interest from the EPR report for the McArthur River Operation. It represents only some of the information presented in the full report.

On this page:

• About the facility
• About the report
• Environmental monitoring
• Human health
• Related link - Full EPR report

About the facility

The McArthur River Operation is located within historic Treaty 10 territory, in the Homeland of the Métis, and is within the traditional territories of the Denesųłiné, Cree, and Métis peoples. The facility is owned by McArthur River Joint Venture (where the partners are approximately 70% Cameco and 30% Orano) where Cameco is the operator. The McArthur River Operation is located within the Athabasca Basin of Northern Saskatchewan, approximately 620 km north of Saskatoon.

Under its current operating licence, Cameco is authorized to operate and modify an underground uranium mine; and to operate primary ore processing, ore slurry loading and waste management facilities, a water treatment plant, effluent storage ponds, surface freeze plants, administration offices, and warehouses. In 2018, Cameco announced that the McArthur River Operation would remain in a state of care and maintenance. In February 2022, Cameco announced its intent to begin the process to transition McArthur River Operation from care and maintenance to production over the course of 2022 and 2023.

About the report

The following summary highlights key areas of interest from the EPR report for the McArthur River 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 the 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 McArthur River Operation environmental risk assessment
• Cameco’s 2020 McArthur River Operation environmental risk assessment
• Cameco’s 2019 McArthur River Operation preliminary decommissioning plan
• the results of Cameco’s environmental monitoring, as reported in annual reports
• the results of the CNSC’s Independent Environmental Monitoring Program (IEMP)
• the results from other environmental monitoring programs and/or health studies (such as studies completed by other levels of government) in proximity to Cameco’s McArthur River 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 McArthur River Operation observed between 2013 and 2021 are similar to the risks posed by natural background 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 McArthur River 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 McArthur River 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.

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 monitoring

Under the IEMP, CNSC staff take samples – for example, of air, water, soil, sediment, vegetation, or 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 2021, a qualified contractor conducted IEMP sampling around the McArthur River 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, fish and moose.

Visit the CNSC’s IEMP web page for more information, including detailed sampling results.

Cameco’s monitoring

Atmospheric releases

Cameco controls airborne emissions from the McArthur River Operation to the environment. At the facility are various potential sources of airborne releases including material handling and transfers of waste rock, vehicle travel on unpaved areas, concrete batch plant operations, wind erosion of waste rock, diesel and propane fuel combustion, underground mine ventilation exhaust and emissions from waste stockpiles. The facility uses a variety of pollution control methods, including watering roads and airstrips, and installing exhaust gas scrubbers and silo filters.

Note: There are no measured airborne emissions data presented in this report because there is no mill at the McArthur River Operation. Cameco estimates airborne releases from the McArthur River Operation, and reports any values that are above the reporting threshold to the National Pollutant Release Inventory.

Liquid releases

Cameco routinely monitors and controls liquid effluent released from the McArthur River Operation to the environment. Wastewater is generated by the facility from drainages, sumps and the underground mine. Wastewater is treated by primary and secondary water treatment plants and pumped into monitoring ponds for sampling. Once treated water meets release criteria it is discharged to the environment at Read Creek. Cameco monitors temperature, conductivity, pH, metals and radionuclides in the effluent released at both of the McArthur River Operation’s discharge points.

The monitoring results (see table 1) show that water releases from the mine water treatment plant were 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 1: Annual average waterborne releases from the McArthur River Operation mine water treatment plant compared with applicable release limits (2013–2021)

Parameter	Licence limit	2013	2014	2015	2016	2017	2018	2019	2020	2021
Arsenic (mg/L)	0.3	0.0017	0.0020	0.0029	0.0011	0.0007	0.0001	0.0001	0.0001	0.0001
Copper (mg/L)	0.3	0.0011	0.0014	0.0011	0.0011	0.0006	0.0004	0.0005	0.0006	0.0005
Lead (mg/L)	0.1	0.0001	0.0008	0.0009	0.0009	0.0001	0.0001	0.0001	0.0001	0.0001
Nickel (mg/L)	0.5	0.0012	0.0034	0.0035	0.0033	0.0015	0.0016	0.0017	0.0015	0.0022
Zinc (mg/L)	0.5	0.0014	0.0022	0.0016	0.0016	0.0019	0.0011	0.0032	0.0019	0.0024
pH (a)	6.0 to 9.5	7.2	7.3	7.3	7.3	7.2	7.5	7.4	7.4	7.4
Radium-226 (Bq/L)	0.37	0.052	0.058	0.065	0.082	0.068	0.063	0.052	0.049	0.029
Total suspended solids (mg/L)	15	1	1	1	1	1	1	1	1	1
Un-ionized ammonia (mg/L) (b)	0.5	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01
Selenium (mg/L)	0.6 (c)	0.0014	0.0024	0.0025	0.0037	0.0019	0.0002	0.0003	0.0003	0.0003
Uranium (mg/L)	2.5 (d)	0.0107	0.0095	0.0089	0.0055	0.0048	0.0049	0.0093	0.0073	0.0082
Molybdenum (mg/L)	N/A (e)	0.1878	0.1865	0.1458	0.185	0.1393	0.0192	0.0084	0.0094	0.0089

1. The pH is taken from every discharge samples. It is not measured in monthly composite samples.
2. Un-ionized ammonia was added to the Metal and Diamond Mining Effluent Regulations (MDMER) in 2021.
3. This is the provincial limit that is not in the CNSC licence.
4. 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.
5. 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.

The monitoring results (see table 2) show that water releases from shaft #3 were 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 average waterborne releases from the McArthur River Operation shaft #3 discharge compared with applicable release limits (2013–2021)

Parameter	Licence limit	2013	2014	2015	2016	2017	2018	2019	2020	2021
Arsenic (mg/L)	0.3	0.0001	0.0001	0.0001	0.0001	0.0002	0.0002	0.0001	0.0001	0.0001
Copper (mg/L)	0.3	0.0002	0.0005	0.0005	0.0010	0.0002	0.0003	0.0002	0.0002	0.0002
Lead (mg/L)	0.1	0.0001	0.0001	<0.0001	0.0001	<0.0001	0.0001	<0.0001	<0.0001	0.0003
Nickel (mg/L)	0.5	0.0017	0.0016	0.0014	0.0019	0.0012	0.0014	0.0013	0.0011	0.0011
Zinc (mg/L)	0.5	0.0172	0.0195	0.0289	0.0384	0.0090	0.0193	0.0185	0.0191	0.0209
pH (a)	6.0 to 9.5	7.2	7.2	7.0	7.0	7.2	7.3	7.2	7.1	7.1
Radium-226 (Bq/L)	0.37	0.107	0.100	0.110	0.112	0.103	0.116	0.098	0.086	0.088
Total suspended solids (mg/L)	15	1	1	1	1	1	1	1	1	1
Un-ionized ammonia (mg/L) (b)	0.5	-	-	-	-	-	-	<0.01	<0.01	<0.01
Selenium (mg/L)	0.6 (c)	0.0002	0.0002	0.0002	0.0002	0.0002	0.0001	0.0001	0.0001	0.0001
Uranium (mg/L)	2.5 (d)	0.0010	0.0008	0.0008	0.0008	0.0009	0.0009	0.0008	0.0008	0.0017
Molybdenum (mg/L)	N/A (e)	0.0062	0.0061	0.0060	0.0055	0.0050	0.0054	0.0038	0.0044	0.0049

1. The pH is taken from every discharge samples. It is not measured in monthly composite samples.
2. Un-ionized ammonia was added to the MDMER in 2021.
3. This is the provincial limit that is not in the CNSC licence.
4. 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.
5. 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.

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 or 1000 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, Cameco assessed the risk to representative persons who had the potential to be the most exposed to contaminants. A total of 5 human receptor groups were identified as being the most exposed for potential radiological and hazardous contaminant exposures. The groups included onsite 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 McArthur River Operation for the 2013–2021 period have remained below the regulatory annual dose limit for the public. This indicates that radiological releases from the McArthur River Operation pose a negligible risk to human health (i.e., 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 McArthur River Operation, 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 McArthur River 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.

To get a snapshot of the health of the population living near the McArthur River 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 McArthur River Operation.

Related link

• Environmental Protection Review Report: McArthur River Operation