McArthur River/Key Lake is the world's largest high-grade uranium mine, operated by Cameco (70% owner and operator) and Orano (30%) in the Athabasca Basin, Saskatchewan. In 2025, McArthur River/Key Lake produced 15.1 million pounds U3O8 (100% basis), meeting revised production guidance. Cameco's total 2025 production was 21.0 million pounds U3O8 (Cameco share) — exceeding the revised guidance of up to 20 million pounds. Cameco also owns 49% of Westinghouse Electric Company (with Brookfield). Cameco's strategy spans the full nuclear fuel cycle from uranium mining through fuel services to reactor technology via Westinghouse. Cameco's 2026 plan for McArthur River/Key Lake is 14-16.5 million pounds of U3O8, after 15.1 million pounds in 2025; Cameco's total 2025 production of 21.0 million pounds (its share) was 10% below 2024's 23.4 million pounds.