Cameco halts Cigar Lake mine after mill outage hits output

Cameco Corp. temporarily halted mining at its Cigar Lake uranium operation in northern Saskatchewan after an outage at the McClean Lake mill that processes the ore, the company said July 1.

The disruption stems from a forced shutdown of the sulfuric acid plant at Orano Canada Inc.'s McClean Lake mill, which is undergoing repairs. With limited ore storage capacity at Cigar Lake, mining activities were paused until sufficient acid is available for milling to resume, Cameco said in a statement. The mill is expected to return to operation in about two weeks.

Orano is working to restore the acid plant and evaluating alternative sources of sulfuric acid while awaiting replacement parts, according to the statement. Cameco said it does not currently anticipate any impact on its 2026 production outlook for Cigar Lake, though a prolonged outage could prompt a reassessment.

Cigar Lake produced 19.1 million pounds of uranium on a 100% basis in 2025, with Cameco's attributable share at 10.4 million pounds. For 2026, the mine is expected to produce between 17.5 million and 18.0 million pounds. Cameco's consolidated attributable uranium production for 2026 is forecast at 19.5 million to 21.5 million pounds.

The suspension marks the second operational disruption for Cameco this year. In May, the company temporarily halted operations at its McArthur River mine and Key Lake mill after severe flooding in northern Saskatchewan caused a partial collapse of the Smoothstone River Bridge, a critical supply route. Cameco established an alternative logistics route and restored production within a short period, maintaining its 2026 guidance of 14.0 million to 16.5 million pounds from those operations.

On July 2, Cameco closed a deal to increase its ownership in the Cigar Lake Joint Venture to 57.418%, up from 54.547%, after acquiring TEPCO Resources Inc.'s 5% participating interest alongside Orano. The higher stake increases Cameco's direct exposure to one of the world's highest-grade uranium deposits with a long reserve life.

Cameco shares traded on the Toronto Stock Exchange at CA$139.59, down 5.7% over the past week and 12.5% over the past month, though up 40.5% over the past year. The stock has gained 30% in the past 12 months on the New York Stock Exchange, where it trades under the ticker CCJ. Uranium peers Energy Fuels Inc. and Uranium Energy Corp. have gained 120.4% and 57%, respectively, over the same period.

The Cigar Lake suspension highlights the operational risk embedded in Cameco's reliance on shared infrastructure. While the company expects a two-week outage to be manageable, any extended disruption at the McClean Lake mill could affect volumes, costs, or delivery timing to customers. The increased ownership stake, meanwhile, concentrates a larger share of Cameco's future uranium output and reserves at a single mine, pairing greater long-term resource exposure with elevated short-term execution risk.

This article is for informational purposes only and does not constitute investment advice.