Roy Lynn Oakley, 67, abandoned his not guilty plea to a two-count federal indictment shortly after entering the courthouse, the day his case had been set for trial.
"Guilty, sir," the graying man told U.S. District Judge Tom Varlan, to one count of disclosing restricted data in violation of the Atomic Energy Act.
The judge said he would review a background report on Oakley before sentencing him May 14 under the deal to six years in prison and three years' supervised release. Oakley could have faced up to 20 years in prison.
Oakley acted alone in trying to sell a handful of uranium enrichment parts first to the French government and then an undercover FBI agent for $200,000 in cash, Assistant U.S. Attorney Will Mackie said.
Oakley tried to sell the parts to the French government, calling French consulates in Atlanta and Chicago and the French Embassy in Washington. The French turned him down and then informed the FBI.
After entering his plea Monday, Oakley avoided reporters seeking comment. His attorneys, federal public defenders Beth Ford and Kim Tollison, did not return a phone call later to their office.
Oakley was a contractor employee with moderate security clearance at the former K-25 uranium enrichment plant in Oak Ridge at least since 2005. He worked as a laborer and escort for other contractor employees dismantling the World War II-era plant, which is being transformed into an industrial park.
The former K-25 site is owned by the Department of Energy, but it is several miles away from other active government installations in Oak Ridge: the Y-12 nuclear weapons warhead plant and the Oak Ridge National Laboratory.
According to the plea deal, Oakley sneaked six pieces of enrichment hardware out in 2006 that he was supposed to have broken apart. The hardware included three 4-inch-long "barrier" tubes for separating highly enriched uranium in K-25's gaseous diffusion process.
Although the barriers are now old technology, they are still classified secrets. "It is not something that we use currently, but it is something that could be used by other countries or organizations," Mackie said.
After a series of recorded phone calls, Oakley, armed with a handgun, met an undercover FBI agent posing as a representative of a foreign government. In a January 2007 meeting, Oakley turned over the nuclear parts in exchange for $200,000 in cash. He was immediately arrested, and remains free on bond pending sentencing.
Energy Department-Oak Ridge spokesman John Shewairy said he could not discuss changes in security at the former K-25 plant since Oakley's arrest. The building where Oakley obtained the nuclear parts is slated for demolition in a few years, he said.