If you plan to drive along Interstate 40 through Tennessee over the next few years, you might want to be extra careful.

The U.S. Department of Energy plans to begin shipping plutonium to the Savannah River Site near Aiken, S.C. as early as Friday -- but state and local authorities won't know any details about the shipments unless there's a serious accident, the Knoxville News Sentinel reports:

The routes that will be used to transport the strategic nuclear material across the country are hush-hush and won't be shared in advance of the project.

"It's extremely classified," said Jonathan Shradar, assistant press secretary with the U.S. Department of Energy in Washington. "We definitely don't confirm."

Shipments could begin as early as Friday, according to the decision DOE announced Sept. 5.

The shipments are so secret that not even the Tennessee Emergency Management Agency -- which usually works with agencies transporting nuclear material -- has been given any information about them, according to the paper.

The shipments are part of the government's effort to consolidate the nation's surplus supply of weapons-grade plutonium in South Carolina. The material will be coming from the Hanford Site in Washington, the Los Alamos National Laboratory in New Mexico, and the Lawrence Livermore National Laboratory in California. In all, the government plans to transport some 2,300 plutonium storage containers from Hanford and almost 700 from Lawrence Livermore and Los Alamos.

Some have speculated that Interstate 40 across Tennessee would be a likely route for the material. The shipments are scheduled to continue through 2010. Plans call for the plutonium to be either converted into a mixed-oxide fuel, or MOX, for use at commercial nuclear power plants or be enclosed in glass logs for eventual transfer to the Yucca Mountain high-level nuclear waste repository being planned in Nevada.

A radioactive metal that was manufactured in large amounts during the Cold War for weapons, plutonium is extremely toxic if handled incorrectly and particularly damaging to the bone marrow.