Case Study

With great ore deposits comes great responsibility.

The world’s highest-grade ones, like those mined at McArthur River, require extra diligence to manage radiation exposure risks underground.

Cameco has always strived to exceed expectations and followed the ALARA principle (as low as reasonably achievable) to ensure its workers are protected from radiation exposure. About five years ago, the company found a way to do this even better, using a remote-controlled pressure washer.

McArthur River uses a raisebore mining method. In this method, a revolving reaming head is pulled up through the orebody creating a vertical tunnel or raise. Once a raise is completed, a high-strength concrete plug is placed from the extraction chamber. Before workers can safely enter the area to remove the reamer and place the backfill plug, the walls and floor of the extraction chamber must be thoroughly washed to remove elevated gamma levels. This is just one of many radiation protection measures that are a routine part of operating a Cameco mine operation.

In 2011, members of McArthur River’s operations team worked with maintenance engineers to procure and customize a mobile pressure floor washer. The machine looks like a miniature fire truck with a long boom and hose at the front and extra hoses on the sides.

“Not only can we do a more thorough job of cleaning these areas with the water cannon, but because we can operate it remotely, we can keep the operator safely away from what is generally a higher risk radiation exposure area,” said general manager Kevin Quesnel.

The old way of cleaning extraction chambers was by hand, using a standard underground water hose. The challenge was managing radiation exposure levels while effectively cleaning the reamer and the extraction chamber. Employees couldn’t get close enough to do an effective cleanup because an open raisebore hole also presented a conventional safety risk.

The equipment is also used throughout the mine for general housekeeping, freeing mine crews from the tedious task so they can focus on mining the ore.

“We’re always looking for ways to improve, be more efficient and more innovative. This is just one example of the maintenance engineering team doing exactly that,” said Quesnel.

The equipment brings both a radiation exposure benefit and strong business justification. McArthur River estimates the remote washing method reduces the cumulative radiation exposure to employees required to clean chambers and equipment on a regular basis by 96.55 mSv/year.

And even with the $530,000 cost to purchase the equipment along with annual operating and maintenance, the automated cleaning method is half as costly per year as the labour-intensive manual process.

“This project will reduce costs by allowing more efficient use of manpower while cleaning the mine, as well as reduce raise cycle times through quicker, more efficient chamber preparation prior to the backfill process,” said Dean Tomolak, who was the project manager for the equipment purchase.

Cameco’s other two underground mines do not currently use the mobile pressure floor washer. Rabbit Lake uses a different mining method which does not require the same level of cleaning. Cigar Lake may consider it in the future when the mine’s access areas expand enough to justify the expense.