Cameco restarts Cigar Lake as McClean Lake mill returns to service

Cameco Corporation (TSX: CCO) has resumed uranium production at its Cigar Lake mine in northern Saskatchewan after processing problems at Orano's McClean Lake mill were resolved.

Ore from Cigar Lake is processed at McClean Lake, so the mine is directly exposed to interruptions at that mill. Cameco said it has begun shipping stockpiled ore to the mill and that its 2026 production outlook for Cigar Lake remains 17.5 million to 18.0 million pounds of U3O8 on a 100% basis, or 9.5 million to 10.0 million pounds on its share.

Cameco suspended mining at Cigar Lake on July 1 after operational problems at McClean Lake halted milling. The issue centered on the mill's sulfuric acid plant. Cameco said at the time that limited ore storage at Cigar Lake left little room to keep mining while milling was offline.

Orano said the McClean Lake mill shut down on June 29 after a problem with an expansion joint in the sulfuric acid production unit. The company restarted production on July 11, completing repairs in 12 days and meeting its target to resume operations within about two weeks. Orano said the outage had not changed its 2026 production expectations for the mill under the current operating plan.

The timeline matched Cameco's earlier assessment that the disruption would be short. When it announced the suspension, the company said it did not expect the outage to affect its full-year outlook for Cigar Lake, while warning that a longer repair or trouble sourcing sulfuric acid could create downside risk.

That risk has now eased. Cigar Lake has produced 174.5 million pounds of uranium concentrate on a 100% basis since commissioning in 2014, according to Cameco.

The outage exposed a constraint in the Athabasca Basin supply chain. Cigar Lake ore is processed only at McClean Lake, about 70 kilometers away, so a mechanical problem at the third-party mill can stop production at the mine. Limited on-site ore storage means that dependency can affect output quickly.

For now the impact looks contained. The outage lasted less than two weeks, stockpiled ore shipments have resumed, and both companies have reiterated that current-year production plans remain intact.

Cigar Lake, which Cameco describes as the world's highest-grade uranium mine, is one of the main supply sources in Saskatchewan's Athabasca Basin. Its restart restores a stream of primary uranium supply as the sector weighs long-term fuel demand from reactor restarts and new nuclear build programs.