The K-25 plant is badly deteriorated and thoroughly contaminated with uranium and a host of other hazardous materials. Tearing down the World War II-era structure is the Department of Energy's highest priority in Oak Ridge.

The project, however, is behind schedule, and there could be additional delays, depending on the budget outcomes for this year and next, according to DOE's Oak Ridge manager.

"We've not officially stretched anything yet, but it may get stretched some," Gerald Boyd said.

The original schedule for demolition of K-25 and other buildings at the former uranium-enrichment site was fall 2008.

After a worker fell through a second-story floor and was seriously injured, DOE and its cleanup manager, Bechtel Jacobs Co., changed the strategy and added a number of safety measures. A new completion date was set at August 2009.

In the Bush administration's budget request for fiscal 2008, documents indicate that closure of the site - now known as the East Tennessee Technology Park - won't be completed until 2010. If the schedule slips, the cost typically goes up.

Boyd said nothing is firm because Oak Ridge officials don't know how much money will be available for the rest of 2007.

But he noted that there's a "fairly substantial" decline in the proposed cleanup funding for 2008. That's about $100 million less than the 2006 spending level.

"We are distressed about the '08 budget, no doubt about that," said Susan Gawarecki, executive director of the Local Oversight Committee, which evaluates environmental projects for local governments.

There's a growing concern about K-25, Gawarecki said. "The race is to take the building down before it falls down," she said.

The mile-long, U-shaped structure was built during the World War II Manhattan Project, and it is "very fragile," Boyd said.

Bechtel Jacobs and its subcontractors are working on K-25 and its sister building, K-27, but they have been unable to ramp up action as planned because of spending restrictions in place.

Boyd said it may be two or three more weeks before officials learn how much money DOE is allotting for Oak Ridge cleanup projects for the remainder of fiscal 2007.

"If we can get what we need this year, then that makes next year a little easier with that lower budget," the DOE official said.

Boyd said it's still possible that the K-25 project could be finished by August 2009, but he didn't sound confident.

Boyd said DOE wants to discuss priorities with the Tennessee Department of Environment and Conservation and the U.S. Environmental Protection Agency before changing schedules. Many of DOE's projects have enforceable milestones under a legally binding cleanup agreement with regulators.