Cameco Suspends Cigar Lake Mining Amid Acid Plant Failure at Orano’s McClean Lake Mill

Cameco Corp. announced a temporary halt to mining at its Cigar Lake uranium mine in northern Saskatchewan after the sulfuric-acid plant at Orano’s McClean Lake mill, which processes the ore, went offline for repairs. With limited ore storage, mining cannot continue until acid is supplied. Cameco expects the mill to restart in roughly two weeks and says the suspension does not change its 2026 production outlook, though extended delays could affect that forecast.

Cameco Halts Cigar Lake Mining as Acid Plant Failure Idles McClean Lake MillThe Globe and Mail (Toronto)

In May, spring flooding collapsed a bridge on the main supply route to the McArthur River and Key Lake sites, causing a two-and-a-half-week production halt at Key Lake and reduced output at McArthur River. Both sites resumed full output after the outage, while Cigar Lake continued operating. In June, Cameco and Orano completed the purchase of TEPCO Resources’ 5 % stake in the Cigar Lake joint venture, raising Cameco’s ownership to 57.4 % and valuing the operation at just over $4 billion. The principal entities involved are Cameco Corp. (TSX: CCO, NYSE: CCJ), Orano, and the former partner TEPCO Resources.

Cameco Halts Cigar Lake Mining as Acid Plant Failure Idles McClean Lake MillThe Globe and Mail (Toronto)

Cigar Lake is projected to produce 17.5–18 million pounds of uranium concentrate in 2024 on a 100 % basis. Cameco’s consolidated 2026 production target remains 19.5–21.5 million pounds. The current suspension is not expected to alter the 2026 outlook unless repairs exceed the anticipated two-week period.

Cameco Halts Cigar Lake Mining as Acid Plant Failure Idles McClean Lake Mill

Cameco Corp., listed on the Toronto (TSX: CCO) and New York (NYSE: CCJ) exchanges, is one of the world’s largest uranium producers. The company’s shares were last reported at $144.56 on the TSX, reflecting investor interest in its low-cost, high-grade assets and its role in supplying nuclear fuel for carbon-free power generation.

The Globe and Mail (Toronto)

Cameco’s release described the halt as “temporary” and linked it directly to the sulfuric-acid plant shutdown at Orano’s mill. Orano is repairing the plant and exploring alternative acid-supply options while awaiting replacement parts. Cameco reaffirmed its 2026 production outlook and noted that prolonged disruption could pose a risk to that forecast.

Cameco Halts Cigar Lake Mining as Acid Plant Failure Idles McClean Lake Mill

The incident highlights the dependence of uranium mining on downstream milling capacity and acid supply. Extended acid shortages could lower the amount of uranium concentrate available to nuclear-fuel producers, potentially affecting utilities that rely on Cameco’s fuel for carbon-free electricity generation.

The Globe and Mail (Toronto)

Cameco will monitor Orano’s acid-plant repairs and any alternative acid procurement. The company will assess any impact on the 2026 production forecast if the outage persists and watch market reactions to the temporary supply constraint.

Cameco Halts Cigar Lake Mining as Acid Plant Failure Idles McClean Lake Mill