Exploration and development of the high grade McArthur River uranium orebody

The McArthur River deposit, discovered in 1988, is recognized as the world's largest, highest grade uranium deposit, with current mineable reserves containing 255 million lbs of U308 at an average grade of 17.33% U308. In addition, the project has resources of 228 million lbs of U308 averaging 12.02% U308. The deposit is in northern Saskatchewan, on the eastern edge of the Athabasca Basin, northeast of the Key Lake mine. The ore is approximately 550 m underground, associated with a major thrust fault, which has caused fracturing of the footwall Athabasca sandstone and gives the potential for significant waterflows near the ore body. Mining this high grade ore body presents serious challenges in controlling radiation and dealing with high water pressures. Non-entry mining will be used in the high grade ore zones. Raise boring will be the primary method to safely extract the ore, with all underground development in waste rock to provide radiation shielding. Water will be controlled by grouting and perimeter freezing. The underground crushed and ground ore slurry will be pumped to the surface and transported in special containers to the Key Lake mill for further processing. The annual production is projected to be 18 million lbs of U308.