Production Begins at Cameco Uranium Mine in Wyo.

CHEYENNE, Wyo. (AP) — Wyoming's newest uranium mine could account for a substantial portion of the state's uranium production in a couple years.

Production began Monday at Cheyenne-based Cameco Resources' North Butte Mine west of Wright in southwestern Campbell County.

The new mine is part of an aggressive expansion program by Cameco despite a soft uranium market. Uranium prices are down 40 percent from two years ago.

Even so, Cameco plans to open five more uranium mines in Wyoming and Nebraska over the next few years.

Cameco officials expect their new mine to produce 300,000 pounds of uranium ore this year, ramping up to 700,000 pounds in 2015.

Wyoming produces more uranium than any other state — about 1.6 million pounds a year, or close to one-third of all U.S. production.