Exelon Corp., which sought the agency's first-ever early site permit in September 2003, would have up to 20 years to seek a license from the NRC to build and operate a reactor at the company's Clinton, Illinois, site, where it already has one nuclear reactor generating electricity.

The decision is a step toward the Bush administration's goal to expand nuclear power to meet growing US electricity demand. Many energy experts also say the US will need more nuclear reactors to replace coal-fired generating plants that emit greenhouse gas emissions linked to global warming.

Exelon has no plans in the short term to build another reactor at the site, a company spokeswoman said.

It would take the NRC about 24 months to review and approve any Exelon request to construct a new reactor at the Clinton location, an agency spokesman said.

Agency staff will officially issue the early site permit for the Clinton location in about 10 days.

The permit is transferable if Exelon decided to sell the existing Clinton nuclear reactor, the NRC said. Exelon said it has no such plans.

The cost to build the 1,043-megawatt Clinton power plant, which came online in 1987, was US$4.25 billion. The reactor can meet the electricity needs of about 1 million homes, according to the company.

Energy Secretary Bodman welcomed the NRC's decision.

"By demonstrating effectiveness and predictability in the licensing process, utilities will have the information they need to make sound business decisions that can lead to the construction of new nuclear power plants," Bodman said.

The NRC is expected to make a decision in the next few weeks on Entergy Corp's request for an early site permit for an additional reactor at its Grand Gulf site in Mississippi, the agency spokesman said.