Cameco Suspends Operations at Saskatchewan's Cigar Lake Uranium Mine

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Written by Danny Levin, Deputy Editor for IIR News Intelligence (Sugar Land, Texas)

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Summary

Cameco on July 1 temporarily suspended operations at the Cigar Lake Uranium Mine in Saskatchewan following a disruption at the McClean Lake Mill, which processes the mine's ore.

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Cigar Lake Uranium Mine/McClean Lake Mill Outages

Cameco has suspended operations temporarily at the high-grade Cigar Lake Uranium Mine in Saskatchewan, Canada, following a shutdown that halted production at the McClean Lake Mill. McClean Lake processes the ore from Cigar Lake.

Operated by the world's second-largest producer of uranium, Saskatoon-headquartered Cameco said on July 1 that operational challenges had caused McClean Lake's sulfuric acid plant to shut down for repairs, halting milling at the site.

"With limited ore storage capacity at Cigar Lake, we have temporarily suspended mining activities until sufficient acid is available to allow milling to resume," the company said. According to Industrial Info Resources data, there are 15 active and proposed Cameco mining projects in Canada, with a total investment value of US$1.75 billion.

The Industrial Info Resources Global Market Intelligence (GMI) Offline Event Database offers detailed reports for the Cigar Lake and McClean Lake outages, while the GMI Plant Database offers key information on the two sites.

Cameco said it expected McClean Lake to return to service in approximately two weeks and did not expect the disruption to impact the 2026 production outlook for Cigar Lake. But there's a risk that the acid unit repairs will take longer than planned and the resumption of extraction at Cigar Lake will be delayed.

High-grade uranium ore slurry from Cigar Lake is trucked in special containers about 70 kilometers (43 miles) to McClean Lake, where it's processed into uranium concentrate (yellowcake).

Mine operator Cameco describes Cigar Lake as the world's highest-grade uranium mine.

Prior to July 2, Cigar Lake was owned by Cameco, Orano Canada and Tokyo Electric Power Company (TEPCO) in a joint venture, but Cameco has closed its acquisition of TEPCO's 5% interest, bumping its ownership stake to 57.41%; Orano's share will rise to 42.58%.

Orano is the majority owner of McClean Lake (77.5%), while Denison Mines holds the remaining 22.5% stake.

Cigar Lake's Potential Expansion

The ongoing outage aside, Cameco has said it plans to continue production and development activities in the operational mine area, while continuing to advance development related to a proposed expansion.

Dubbed CLExt, the expansion is designed to extend the mine's life from 2031 to 2036. Capital efforts include construction of a freeze pad, freeze distribution, and underground infrastructure. However, the project is in its early planning phase, where plenty of factors can delay, alter or eliminate proposed investment.

Also planned for Cigar Lake are maintenance shutdowns in the second quarters of 2027 and 2028.

The suspension of operations at Cameco's Cigar Lake Uranium Mine comes on the heels of the company temporarily idling its Key Lake Mill and reducing activity at its McArthur River Mine in Saskatchewan in May, due to a bridge collapse in the region. The sites returned to full production activities on May 27.

Cameco in the U.S. Nuclear Reactor Supply Chain

Cameco has transitioned from a pure uranium producer to a major player in the nuclear reactor supply chain, co-owning Westinghouse--the only company with fully designed, licensed and operating advanced large-scale reactors in the U.S. Cameco owns a 49% interest, while capital investment firm Brookfield owns the remaining 51%.

Last month, the U.S. Department of Energy announced $17.5 billion in conditional loans to speed up the construction of 10 large nuclear reactors, all of which would feature Westinghouse's technology. For more information, see June 24, 2026, article - U.S. Plans to Loan $17.5 Billion to Boost Nuclear Reactor Construction.

Key Takeaways

• Cameco on July 1 temporarily suspended operations at the Cigar Lake Uranium Mine in Saskatchewan following a disruption at the McClean Lake Mill.
• Mining at Cigar Lake could resume by July 16, but there's no guarantee.

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