"The U.S. has said Iran doesn't need nuclear power because of its oil and natural gas reserves," said Edwin Lyman, a senior scientist. "Iran turns around and says, 'We want to mitigate greenhouse gas emissions, just like you do.' There's this kind of doubletalk."

Lyman said it's also unclear if the U.S. really needs new enrichment facilities, when it could instead lift import restrictions from other countries.

"There's a kind of heady gold rush going on," Lyman said. "But it will be a long time before it's really clear what's realistically justified."

The Snake River Alliance, an Idaho anti-nuclear group, argues enrichment plants are accompanied by health and environmental hazards. USEC's Paducah, Ky., facility, for instance, has been targeted by federal lawsuits because of chemicals that contaminate groundwater there after a half-century of operations.

The Idaho group also criticizes Areva's attempt to secure tax breaks for its project.

Still, Idaho Falls, where the Idaho National Laboratory is the largest employer, wants the plant, which would employ about 250 people. Many residents are comfortable with the idea of reactors in their back yard.

Ron Longmore, Bonneville County's elected clerk, calculates the Areva facility would generate about $4 million annually in new property taxes, even with the proposed tax breaks.