Environment & Safety
Safety
We manage the safety of our workers through programs, systems, and standards, with our Safety, Health, Environment and Quality (SHEQ) Policy providing overarching guidance. There are many aspects of the management system that contribute to a safe work environment, a few examples include:
- Risk assessments help identify issues and determine the appropriate controls; the corrective action process verifies that incidents and near misses are reported, tracked, investigated and shared with colleagues; and emergency preparedness and planning prepare us to respond to serious incidents.
- We have developed 12 corporate safety standards to help protect our workers from our most common hazards. Some standards guide our general safety practices, such as our job hazard analysis and our job task observation, and other standards deal with specific hazardous situations (similar to other companies’ life saving rules): such as fall protection, confined space entry, rigging and hoisting, and control of hazardous energy (also referred to as lockout/tagout).
- Routine audits are conducted to monitor compliance with regulations and our own requirements. These and other aspects of the management system are routinely examined to verify that they continue to be effective at keeping our workers safe.
Radiation Protection
Radiation risks are effectively managed at McArthur River and Key Lake. Each operation has a formal radiation protection program and dedicated personnel who ensure that doses to workers are as low as reasonably achievable. The programs require that radiation protection is considered in the physical design of all facilities and operating procedures. They also provide for systematic monitoring of radiation in work areas and track exposures of individual workers using a combination of monitoring devices and health testing. Radiation exposures at McArthur River and Key Lake are far below below the regulated limits.
Environmental Protection
At Cameco, protection of the environment is one of our highest corporate priorities during all stages of our activities, from exploration through development, operations, decommissioning, and reclamation.
We monitor our performance by tracking corporate and site-specific key performance indicators, conducting environmental monitoring programs, and regularly auditing our adherence to the requirements of these programs We use the information from all of our programs to help us to identify opportunities to improve.
Environmental management system
We have a ISO 14001-certified environmental management system used across our operating sites, which is supported by a corporate Environmental Management Program that outlines the operating requirements sites must meet. Our environmental management system encourages and promotes continuous adaptation of our practices based on new information and technologies.
Environmental risk assessments
We complete environmental risk assessments to systematically identify, quantify, and to characterize the potential risks to the environment, workers, and the public. We use our environmental risk assessments to inform our decisions and actions. Additionally, we complete an iterative process, where required, to verify that our proposed measures to protect the environment and the public are effective. We review or update the assessments every five years, incorporating results from our environmental monitoring programs and other scientific advances.
Environmental performance reports
For our Saskatchewan operations, every five years we also compare monitoring data collected during the reporting period against predictions contained in approved environmental risk assessments or environmental assessments. By reviewing the data from the performance reports and conducting risks assessments, we are able to demonstrate that human health and the environment in the vicinity of our Saskatchewan operations remains protected. Results from these analyses are also used to inform changes to the environmental monitoring programs conducted at each operation.
Corrective action process
We have a corrective action process in place to systematically investigate and address the causes of non-conformance to regulatory requirements or internal standards. The process includes classifying the non-conformance, assigning the appropriate level of investigation (dependent on incident significance), and tracking the recommended corrective actions to prevent and mitigate similar occurrences.
Audits
To support our culture of continuous improvement, our processes and operations undergo regular audits, including:
- Our environmental management system is audited by a third-party every three years as a requirement to maintain our ISO 14001 certification.
- Our SHEQ team conducts an internal audit of our SHEQ programs on a three-year cycle. The total audit scope is split in half and executed on a rotating basis. This means that all our sites undergo at least two audits to cover all aspects of our SHEQ programs within every three-year period. The audit follows the ISO 19001 process and encompasses our environmental and safety programs.
- We also maintain and implement an internal audit program at our corporate office. Results and recommendations from this systematic and documented process are presented to senior management, who are responsible for implementing them and correcting any deficiencies. The internal audit group reports to the audit and finance committee of the board.
Environmental Monitoring
Comprehensive monitoring programs are in place at the McArthur River and Key Lake operations to help ensure that the surrounding environment is protected. Samples of water, air, soil, plants and fish are collected from numerous locations around the sites and tested to confirm that environmental protection systems are effective. Monitoring results are submitted to federal and provincial regulatory authorities for review. Cameco also supports independent regional monitoring downstream of its Saskatchewan operations to ensure there are no cumulative effects on the regional watershed. The extensive monitoring undertaken at McArthur River and Key Lake has identified no significant impact on the surrounding environment.
Environmental Incidents and Other Events
Environmental incidents and other events are reported to regulatory agencies as required by federal and provincial regulations.
Latest incidents or events:
McArthur River
| Date | November 30, 2025 |
| Incident | Radiation Action Level Exceedance |
| Details | Two workers received elevated doses – one exceeding the weekly radiation action level, and the other exceeding the quarterly radiation action level. |
| Corrective Action | An investigation is underway and regulators were notified. |
| Environmental Effect | N/Ano measurable impact to the environmentLevel 1 - No measurable impact to the environmentLevel 1 - No measurable impact to the environment |
- Past reporting
McArthur River
Date November 30, 2025 Incident Radiation Action Level Exceedance Details Two workers received elevated doses – one exceeding the weekly radiation action level, and the other exceeding the quarterly radiation action level. Corrective Action An investigation is underway and regulators were notified. Environmental Effect N/Ano measurable impact to the environmentLevel 1 - No measurable impact to the environmentLevel 1 - No measurable impact to the environment Date Oct. 31, 2025 Incident Reportable Spill, Discharge, Discovery or Release Details Water overflowed a shaft exhaust fan containment sump and was released to the ground. Corrective Action A sump pump was found to be set to automatic but was not functioning. The pump was set to manual mode to remove the water. The incident is under investigation and regulators were notified. Environmental Effect Level 1 - No measurable impact to the environment no measurable impact to the environmentLevel 1 - No measurable impact to the environmentLevel 1 - No measurable impact to the environment Date Oct. 11, 2025 Incident Lost-Time Injury Details An employee sustained a hand injury while handling a drill rod. The worker was escorted to the health centre and was provided medical treatment, then sent off-site for additional assessment and treatment. Corrective Action Regulators have been notified, and an investigation has been initiated. Environmental Effect no measurable impact to the environmentN/A Date Sept. 6, 2025 Incident Potential Lost-Time Injury Details A worker was removing a pin on a hoist drum brake assembly. Movement of the brake assembly occurred, resulting in a hand injury to the worker. The worker was sent off-site for assessment and treatment. Corrective Action Regulators have been notified, and an investigation has been initiated. Environmental Effect no measurable impact to the environmentN/A Date May, 2025 Incident Radiation Action Level Exceedance Details A mining employee received a radiation dose exceeding the 1 mSv weekly action level. The elevated result was identified on July 14, 2025, upon receipt of the monthly dosimetry results for May. Corrective Action Regulators have been notified and an investigation has been initiated. Environmental Effect no measurable impact to the environmentN/A Date June 30, 2025 Incident Dangerous Occurrence Details A mine vehicle made accidental contact with the back end of another vehicle while it was parked waiting at the bottom of the ramp to proceed. The workers were taken to the on-site health center for assessment. Corrective Action The incident is under investigation. Environmental Effect no measurable impact to the environmentN/A Date June 27, 2025 Incident Lost-Time Injury Details An underground construction worker was washing out a cement remixer and sustained an injury to their right hand. Corrective Action The worker was escorted to the health centre and was provided medical treatment, and was then sent off-site for additional assessment and treatment. The area was frozen and investigation commenced. Environmental Effect no measurable impact to the environmentN/A Date April 6, 2025 Incident Radiation Action Level Exceedance Details An employee operating a raise bore drill received a radiation dose of 1.02 mSv over a five-day period, exceeding the weekly action level of 1 mSv/week. Preliminary investigation suggests there was inadequate ventilation during the backfill of a mined-out raise bore chamber. Corrective Action The worker left the work area after observing a warning on the in-situ radon progeny monitor. Supervisors were notified and an investigation into potential causes was initiated. Environmental Effect no measurable impact to the environmentN/A Date March 17, 2025 Incident Reportable Release Details Operations detected a decrease in the level of a monitoring pond that was holding treated water, to 85% from 88%. Corrective Action Once the water quality results for the pond were confirmed to meet release limits, the pond was released to the environment as per procedure. A tear in the pond liner is suspected as the cause of the release. The pond will be kept off-line until a proper liner inspection can be completed when safe to do so once the pond is free of ice. Environmental Effect no measurable impact to the environmentN/A Date Feb. 13, 2025 Incident Radiation Action Level Exceedance Details Eleven contractors involved in the relining of the SAG Mill had a weekly radiation dose greater than the 1 mSv action level. Corrective Action The CNSC was notified, and the event is under investigation. Environmental Effect no measurable impact to the environmentN/A Date Jan 25, 2025 Incident Event Requiring Reporting to the Duty Officer Details A worker was taken to the health center for assessment and treatment due to a non-occupational medical emergency. Following assessment and treatment, the worker was released. No off-site medical support was required. The CNSC Duty Officer was notified. Corrective Action N/A Environmental Effect no measurable impact to the environmentN/A Date Jan 18, 2025 Incident Lost-Time Injury Details While attempting to remove a stuck back fill tool, a worker suffered a crush-type injury to their hands. Corrective Action The worker was escorted to the health center and has been sent off-site by air ambulance for additional assessment and treatment. The scene has been frozen for further investigation and the injury has been reported to regulators. Environmental Effect no measurable impact to the environmentN/A Date December 20, 2024 Incident Lost-Time Injury Details An underground worker suffered a strain to their back while bending over to adjust equipment. First aid was provided and the worker completed the rest of their rotation to December 25th without restrictions.
The injury was reclassified as a lost time injury when the worker was unable to return for their next rotation on January 8th.
The injury has been reported to regulators.
Corrective Action Worker was provided first aid and returned to work. Environmental Effect no measurable impact to the environmentN/A Date Nov. 25, 2024 Incident Potential Lost-Time Injury Details While attempting to troubleshoot a plugged line, the worker was sprayed in the face and eye. The worker was assessed and treated on-site, and then flown off-site on a scheduled flight for additional assessment. The CNSC duty officer was notified. Corrective Action A preliminary report found the line was plugged and did not have a bleed valve to release the pressure. The hazard of the pressurized line was not well identified and controlled. Environmental Effect no measurable impact to the environmentN/A Date Nov. 4, 2024 Incident Reportable Discharge Details A valve on a tank of argon gas developed a leak. Corrective Action The area was roped off to allow the argon to safely vent. The CNSC Duty Officer, the Spill Report Center and the Environment Business Services portal were notified. Environmental Effect no measurable impact to the environmentN/A Date Oct. 29, 2024 Incident Lost-time Injury Details An emergency response team member was injured by a high-pressure water stream during a training exercise involving a ground monitor. The worker was provided medical treatment on-site and had an additional assessment off-site. Corrective Action An investigation is underway. The CNSC and LRWS have been notified. Environmental Effect no measurable impact to the environmentN/A Date Oct. 26, 2024 Incident Lost-time Injury Details A worker’s finger was injured while attempting to install a drainpipe. The worker was escorted to the health centre for care and was sent off-site for additional assessment and treatment. Corrective Action An investigation is underway. The likely cause was a miscommunication between two workers while repositioning the pipe and a lack of hazard identification and control of the pinch point. Environmental Effect no measurable impact to the environmentN/A Date July 1, 2024 Incident Recordable Release Details Approximately 51 cubic meters of industrial water overfilled and released to the ground at the industrial water head tanks. The incident was caused by a loss of communication to the level indicators in the tanks. Corrective Action The central control operator ceased filling the tanks. The faulty communication component was replaced and an additional DCS alarm was added to alert if the loss of communication occurs again. Environmental Effect no measurable impact to the environment1 Date June 21, 2024 Incident Reportable Discharge Details During the process of directly discharging clean water from Shaft 3, the discharge valve was closed. This resulted in approximately 170 cubic meters of water overfilling the industrial water storage tanks and reporting to the ground. Corrective Action The discharge valve was opened and the flow of Shaft 3 water to the approved discharge point resumed. The faulty valve will be inspected and repaired. The provincial spill center and the CNSC duty officer were notified. Environmental Effect no measurable impact to the environment1 Date April 22, 2024 Incident Reportable Release Details On April 22, 2024, approximately 40 m3 of treated effluent was released as a result of a liner tear in a monitoring pond. Lab analysis completed confirmed the water was of good quality and met regulatory limits for release to the environment. Corrective Action The pond has been drained and the liner will be repaired by trained personnel. Environmental Effect no measurable impact to the environment1 Date April 7, 2024 Incident Emergency transport to external medical facilities Details The emergency response team (ERT) was activated to respond to a non-occupational medical emergency for an underground worker. The worker was taken to the health centre for assessment and treatment. While the ERT was activated, the team assisted a second worker who received an injury to their face while observing a coworker operating a handheld hammer drill. Corrective Action The ERT helped both workers report to the on-site health centre. Both workers were sent off-site by air ambulance for additional medical assessment. Environmental Effect not applicableN/A Date March 7, 2024 Incident Radiation Action Level Exceedance Details Regular monitoring determined the dose for two workers had exceeded the weekly action level. The quarterly dose estimate for one of the workers also exceeds the quarterly action level. The annual dose estimates for both workers are well below the regulatory limit. Corrective Action Preliminary investigation suggests that the exposure may be linked to completing multiple manual measurements of the elevation of the concrete while backfilling a production raise underground. The site is investigating the procedure for this task to ensure it is being performed consistent with the As Low As Reasonably Achievable (ALARA) principle. Environmental Effect not applicableN/A Cameco Environmental Effect Rating
- Level 1 - no measurable impact to the environment
- Level 2 - negligible impact
- Level 3 - short-term, seasonal impact
- Level 4 - mortality of some species, but not affecting ecosystem function
- Level 5 - impairment of ecosystem function
- N/A - not applicable
Key Lake
| Date | January 23, 2026 |
| Incident | Reportable Spill, Discharge, Discovery or Release |
| Details | Anhydrous ammonia released to the ground within a fenced area while a truck was unloading ammonia. The material was discovered after the truck was unloaded. There were no effects to the truck driver working near the area or any other personnel on site. |
| Corrective Action | An investigation was initiated and regulators were notified. |
| Environmental Effect | Level 1 - no measurable impact to the environment |
- Past reporting
Key Lake
Date January 23, 2026 Incident Reportable Spill, Discharge, Discovery or Release Details Anhydrous ammonia released to the ground within a fenced area while a truck was unloading ammonia. The material was discovered after the truck was unloaded. There were no effects to the truck driver working near the area or any other personnel on site. Corrective Action An investigation was initiated and regulators were notified. Environmental Effect Level 1 - no measurable impact to the environment Date Dec. 12, 2025 Incident Radiation Action Level Exceedance Details An employee received a dose estimated to be above the weekly action level of 1 mSv. Corrective Action The worker provided additional samples, and an intake assessment was completed. The regulatory agencies have been notified. Environmental Effect no measurable impact to the environmentN/A Date Dec. 10, 2025 Incident Event Requiring Reporting to the Duty Officer Details A small fire was reported at the reverse osmosis plant. Corrective Action The emergency response team and the electrical department worked together to determine the source of the fire and extinguish it. There were no injuries associated with this event. The event was reported to the regulatory agencies. Environmental Effect no measurable impact to the environmentN/A Date Nov. 19, 2025 Incident Radiation Action Level Exceedance Details An employee working inside the vertical calciner room received an estimated dose above the weekly radiation action level of 1 mSv. Corrective Action An investigation was initiated, and regulators were notified. Environmental Effect no measurable impact to the environmentN/A Date June 25, 2025 Incident Radiation Action Level Exceedance Details During the quarterly radiation report review, it was noted that an employee received an estimated radiation dose above the weekly action level of 1 mSv. Corrective Action Regulatory agencies have been notified. Environmental Effect no measurable impact to the environmentN/A Date July 20, 2025 Incident Event Reclassification - Lost-Time Injury Details A release of ammonia gas occurred while a worker was completing maintenance activities in the ammonia vapourizer shack. The worker immediately left the area and reported to the on-site health centre for assessment and treatment. The event was reported as a Dangerous Occurrence. Corrective Action Cameco has subsequently been informed that the worker will miss work due to this event. As a result, the event has been reclassified as a Lost-Time Injury. Environmental Effect no measurable impact to the environmentN/A Date Aug. 1 and 16, 2025 Incident Radiation Action Level Exceedance Details Two workers had an exposure to uranium ore material related to work in the leaching mill area. The dose estimates were above the quarterly action level of 5 mSv. Corrective Action The regulatory authorities have been notified, and the cause of the exposure is under investigation. Environmental Effect no measurable impact to the environmentN/A Date July 26, 2025 Incident Radiation Action Level Exceedance Details A worker had an exposure to uranium ore resulting in a dose estimate above the quarterly action level of 5 mSv. Corrective Action The regulatory authorities have been notified, and the cause of the exposure is under investigation Environmental Effect no measurable impact to the environmentN/A Date June 25, 2025 Incident Lost-Time Injury Details A worker was lifting a piece of grating on a pallet that was to be loaded into the box of a truck. When the worker lifted the corner of the grating, the worker injured their arm. Corrective Action The worker was assessed and initially placed on restricted duties. Subsequent offsite treatment requirements have resulted in the lost-time injury classification. Environmental Effect no measurable impact to the environmentN/A Date June 14, 2025 Incident Emergency Transport to External Medical Facilities Details A McArthur River employee suffered a significant medical emergency while at the Key Lake Operation. The employee was treated on-site and then transported to an off-site hospital by air ambulance. The Key Lake emergency response team responded to the event and the incident command at McArthur River was convened. Corrective Action N/A Environmental Effect no measurable impact to the environmentN/A Date June 8, 2025 Incident Event Requiring Reporting to the Duty Officer Details The Emergency Response Team responded to a non-occupational medical event near a permanent camp on a walking trail. The individual was taken to the health centre for treatment. Corrective Action N/A Environmental Effect no measurable impact to the environmentN/A Date May 28, 2025 Incident Lost-time injury Details Worker was moving rolls of carpet when they injured their lower back. Discomfort increased over subsequent days resulting in time off. Corrective Action The worker and supervisor reported to the Health Centre on June 2nd for assessment. Lifting techniques and proper storage of tools and materials was reviewed with the crew following the event. Environmental Effect no measurable impact to the environmentN/A Date May 21, 2025 Incident Event Requiring Reporting to the Duty Officer Details The Emergency Response Team, working with a site services water truck and SaskPower heavy equipment operators, suppressed a small bush fire. The fire was located on the haul road between Key Lake and McArthur River near a SaskPower camp. Corrective Action N/A Environmental Effect no measurable impact to the environmentN/A Date May 13, 2025 Incident Radiation Action Level Exceedance Details A worker had an exposure to calcined yellowcake material while cleaning inside the calciner room. The resulting dose estimate for the worker was above the weekly action level of 1 mSv. Corrective Action The worker was placed on enhanced total urine collection and an investigation was initiated. Environmental Effect no measurable impact to the environmentN/A Date April 12, 2025 Incident Reportable Release Details An employee identified vapour being released from the bulk argon tank. Corrective Action A safe work plan was completed and the leak was isolated and ceased. The leak was due to a cracked pressure release valve. The tank vendor is scheduled to assess and replace any pressure release valves as required. There were no injuries from this event. Environmental Effect no measurable impact to the environmentN/A Date April 7, 2025 Incident Event Requiring Reporting to the Duty Officer Details Deterioration and deformation was noted on the tank lids and walkways on top of the tanks in the Bulk Neutralization area. Corrective Action The walkways on top of the tanks were barricaded to restrict access until remediation is completed. An investigation has been initiated. Environmental Effect no measurable impact to the environmentN/A Date March. 28, 2025 Incident Event Requiring Reporting to the Duty Officer Details The front axle of a trailer caught fire returning from McArthur River after being unloaded. The driver believes the trailer’s brakes had locked on. Corrective Action The driver was able to extinguish the fire and ERT responded to the scene and applied additional water as preventative fire control. Regulators were notified. Environmental Effect no measurable impact to the environmentN/A Date Feb. 28, 2025 Incident The death of any person at a nuclear facility Details An employee of another company was brought to site for assessment of heath concerns. The individual received treatment, however their condition worsened and they passed away. The RCMP were called and debriefed. The RCMP deemed the death non-suspicious and that they would not be required to visit site. Regulatory agencies have been notified. Corrective Action N/A Environmental Effect no measurable impact to the environmentN/A Date Feb. 2, 2025 Incident Reportable Discharge Details A rental argon tank was found to be leaking argon as a gas and liquid from a damaged pressure release valve. Corrective Action Site services cleaned up the spill and the valve was reset and reinstalled. The vendor has been contacted to conduct service on the rental tank. Environmental Effect N/AA/N Date January 9, 2025 Incident Reportable Discharge Details An increase in seepage flow rates to the Reservoirs #1 and #2 underdrain system was reported on December 27, 2024 as a release to secondary containment.
Increased monitoring in this area subsequently indicated an increase in groundwater elevation surrounding the Reservoirs.
In reviewing the additional monitoring and given the potential that leakage from the reservoirs is impacting surrounding groundwater levels, this event is being reclassified as a reportable discharge.
Provincial and federal regulators have been notified.
Corrective Action An investigation into the cause of the discharge is underway along with daily inspections and increased monitoring, including water level and groundwater chemistry.
Ground water quality samples collected to date, from around the Reservoirs, returned results within historical range.
Environmental Effect 1A/N Date May 16, 2023 (reclassified January 4, 2025) Incident Lost-Time Injury Details Worker was lifting a hitch to connect a trailer to a loader resulting in an injury to the worker's shoulder. The worker was assessed at the site Health Center, placed on modified duties, and has undergone treatments since the incident. Additional treatment is required that will result in the worker being away from work. Accordingly, the injury has been reclassified as a lost time injury (LTI). Corrective Action Hand crank jack has been installed on the trailer hitch. Environmental Effect N/AA/N Date November 25, 2024 Incident Lost-Time Injury Details Worker was driving a snowmobile when it tipped on a slope in the trail resulting in an injury to the worker's knee. The worker was assessed at the site Health Center and placed on restricted duties for the remainder of their shift. A secondary assessment by an offsite medical professional determined the worker was unable to return to work. This was reclassified as a lost-time injury on December 13, 2024. Corrective Action Uneven surface on the packed ice created a hazard causing the snowmobile to tip. Environmental Effect N/AA/N Date November 27, 2024 Incident Reportable Release Details A power outage resulted in a release from a sump. More specifically, water overflowed from the sump, which first released to secondary containment with approximately 8 m3 released to the ground. This event is classified as a reportable release. Corrective Action Site services cleaned up the area. Provincial and federal regulators were notified. Environmental Effect 1A/N Date Oct. 17, 2024 Incident Dangerous Occurrence Details An arc flash occurred when an electrician closed the door to an electrical cabinet after inspection. There were no injuries from this event. Corrective Action The electrician locked out the cabinet and contacted their supervisor. The supervisor called the electrical engineer and maintenance general supervisor for additional support. The cause was deemed to be an electrical fault to the ground inside the cabinet. The event has been entered into the Cameco Incident Reporting System for further investigation. The CNSC and LRWS have been notified. Environmental Effect N/AA/N Date Oct. 12, 2024 Incident Unusual Incident Details A radiation protection officer (RPO) and two instrumentation technicians had work planned for a nuclear density gauge (NDG) in the crushing and grinding mill area. When the RPO began conducting a gamma survey to isolate the NDG before work began, they found the shutter on the NDG would not close. Corrective Action The NDG was tagged out and the area secured to prevent workers from entering. The incident is under investigation. Environmental Effect N/AA/N Date Oct. 9, 2024 Incident Radiation Action Level Exceedance Details Dosimetry sampling and analysis for an employee working in the calciner indicated a weekly radiation action level (> 1 mSv) was exceeded. Corrective Action An investigation is underway. The CNSC has been notified. Environmental Effect N/AA/N Date Sept. 2, 2024 Incident Dangerous Occurrence Details A loader backed into a light duty vehicle due to insufficient communication between workers, causing front end damage. The vehicle driver was not injured. Corrective Action N/A Environmental Effect N/AA/N Date Sept. 2, 2024 Incident Event Requiring Reporting to the Duty Officer Details A contractor was stepping down from an elevated platform and stepped onto a flange resulting in an injury. The site Emergency Response Team (ERT) responded, transporting the individual to the site health centre for assessment and treatment. Corrective Action N/A Environmental Effect N/AA/N Date June 5, 2024 Incident Reportable Event Details A worker was lifting a tooling apparatus and felt pain in their elbow. The injury was initially classified as a restricted work event and the worker continued to perform modified duties. A secondary assessment by an offsite medical professional determined further treatment was required, and the event was reclassified as a lost-time injury on June 5, 2024. Corrective Action N/A Environmental Effect N/AA/N Date May 27, 2024 Incident Event Requiring Reporting to the Duty Officer Details A shutter cover was found to have been improperly placed over a nuclear density gauge, allowing process material from a leaking pipe to drip directly onto it and causing corrosion damage. The gauge was not leaking. Corrective Action The cover was properly placed over the gauge. The gauge was removed from service and will be disposed. Environmental Effect no measurable impact to the environment1 Date May 18, 2024 Incident Dangerous Occurrence Details During an inspection of the turbine driver unit in the acid plant building, a one-inch steam drain hose from the high-pressure side of the turbine ruptured while the operator was nearby, spraying high-pressure steam in the opposite direction of the operator. The operator was using all appropriate PPE. No injuries were reported. Corrective Action The operator shut down and isolated the turbine driver unit and removed the ruptured drain hose. The area is being inspected to determine the extent of condition. The event has been entered into the Cameco Incident Reporting System (CIRS) for further investigation. Environmental Effect no measurable impact to the environment1 Date May 3, 2024 Incident Reportable Discharge Details At 3:00 a.m., approximately 150 m3 of treated industrial water was released to the ground from a manhole near the acid plant. The volume exceeds the reporting threshold of 100,000 L. Corrective Action Environment personnel completed a visual site assessment, identified a cracked valve and collected a water sample. The leaking valve inside the manhole was isolated by closing another valve upstream. Repairs are underway.
The incident was reported to the CNSC and Saskatchewan Ministry of Environment.
Environmental Effect no measurable impact to the environment1 Date April 27, 2024 Incident Reportable Discharge; Dangerous Occurrence Details During routine maintenance, while draining water containing residual ammonia from the ammonia vaporizer, the 1” drain hose ruptured. This resulted in the release of ammonia vapor inside the vaporizer building which vents to the atmosphere.
At the time of the event, an operator was working next to the hose as it ruptured. The operator was utilizing all appropriate PPE and there was no injury as a result of this event.
Corrective Action Operator utilized the safety shower to remove any potential ammonia substances from the release and evacuated the vaporizer building. The monitoring system triggered automated shutdown of the ammonia systems. The Safety department tested ammonia levels and determined there was no immediate risk to the health and safety of workers. The area was roped off until residual ammonia levels decreased.
The incident was reported to the CNSC and Saskatchewan Ministry of Environment.
Environmental Effect not applicableN/A Date March 12, 2024 Incident Reportable Spill, Discharge, Discovery or Release Details Following routine review, the Industrial Water Reservoir level was found to be decreasing below the normal operating level. Upon investigation, the industrial water pipeline located underground was determined to be leaking and the industrial water (treated effluent) was found at the surface approximately 85 meters south of the Ore Receiving building. The pipeline, which supplies the industrial and fire protection water, needed to be shutdown, resulting in production being temporarily halted. The amount of industrial treated water released is above the reporting threshold of 100,000 L. Corrective Action The incident was reported to the CNSC and Saskatchewan Ministry of Environment. Excavation of the area identified a failed coupling, which has been repaired. Hot work on site had been prohibited and fire watch rounds were implemented until the fire protection systems were fully restored. Production resumed on the morning of March 14, 2024. Environmental Effect no measurable impact to the environment1 Date February 27, 2024 Incident Lost-Time Incident Details While drilling a hole, a worker caught their glove in the spade bit, resulting in a cut to their finger. The worker was assessed at the site Health Center and the injury was initially classified as a restricted work event. A secondary assessment by an offsite medical professional determined the worker was unable to return to work. This was reclassified as a lost-time injury on March 14, 2024. Corrective Action A lack of hazard recognition and improper tool use was determined to be the cause. Environmental Effect not applicableN/A Date January 20, 2024 Incident Radiation Action Level Exceedance Details While building scaffold in the horizontal calciner, two workers were exposed to calcined yellowcake material resulting in dose estimates above the weekly action level of 1mSv. The workers had worn their coveralls into a lunchroom trailer. Investigation determined the trailer had detectable levels of contamination, requiring it to be thoroughly washed and re-tested to verify cleanliness. Corrective Action Following a review, both workers were placed on enhanced monitoring and an investigation commenced. The work procedure was revised for this area which includes a decontamination process. The event has been reported to the CNSC. Environmental Effect not applicableN/A Cameco Environmental Effect Rating
- Level 1 - no measurable impact to the environment
- Level 2 - negligible impact
- Level 3 - short-term, seasonal impact
- Level 4 - mortality of some species, but not affecting ecosystem function
- Level 5 - impairment of ecosystem function
- N/A - not applicable
Decommissioning
Detailed plans and financial guarantees are in place to provide for decommissioning of the McArthur River and Key Lake sites when operations end. Decommissioning will include removal of all buildings and equipment and landscaping and re-vegetation of disturbed areas. All underground workings and other mine and mill facilities will be sealed off and secured. A monitoring program will be in place to ensure the sites remain in a secure and stable state for the long-term.
For more information, see:
Preliminary Decommissioning Plan - Summary - McArthur River Operation
Preliminary Decomissioning Plan - Summary - Key Lake Operation
Environmental Risk Assessment
All new, or substantially changed, mining developments may be subject to environmental risk assessments (ERAs) to identify potential effects on the environment. ERAs follow guidance provided by CSA and various agencies, such as Health Canada (HC), Environment and Climate Change Canada (ECCC), Canadian Council of Ministers of the Environment (CCME) and the Canadian Nuclear Safety Commission (CNSC).
In 2020, Cameco completed a detailed quantitative environmental risk assessments (ERA) for its McArthur River and Key Lake Operations to align with the standardized requirements found in CSA N288.6-12 Environmental risk assessment at Class I nuclear facilities and uranium mines and mills (CSA 2012).
Public Summary - Environmental Risk Assessment - McArthur River Operation (PDF 6.7 MB)
Public Summary - Environmental Risk Assessment - Key Lake Operation (PDF 3.8 MB)
Tailings Management
Tailings, or what remains of the ore after the uranium has been removed at the Key Lake mill, is placed in the Deilmann tailings management facility. Commissioned in 1996, the facility is built into the mined out Deilmann pit and is designed to safely contain the tailings during continuing operations and after decommissioning. Tailings are placed in the pit under a water cover. During operations, groundwater is collected from a series of wells around the facility and is treated prior to release to the environment. When operations cease, the tailings will become a solid dense mass and groundwater will flow around the tailings, rather than through them, to minimize environmental impact.
Prior to 1996, tailings from the Key Lake mill were deposited in a surface tailings management facility approximately 600 metres by 600 metres and 15 metres deep. The facility was constructed five metres above the groundwater table and used a modified bentonite liner to isolate the tailings from the surrounding soil.
Regulatory Oversight
The primary regulator for the McArthur River and Key Lake operations is the Canadian Nuclear Safety Commission (CNSC). These operations are also subject to regulatory oversight from several other federal and provincial agencies including Saskatchewan Ministry of Environment. Federal and provincial regulators conduct regular site inspections and audits to verify that people and the environment are protected. Uranium mining and milling operations in Canada are licensed by the CNSC.
Sustainability at Cameco
When measuring the sustainability and ethical impact of a company, environmental, social and governance (ESG) are key factors considered by the public and investors. Sustainability and ESG matters have been an important focus at Cameco for many years and we have a strong performance record.