KNOXVILLE, Tenn. - The Watts Bar Nuclear Plant has resumed operation - making it the only commercial nuclear station in the United States producing electricity for homes and factories and isotopes for bombs.

The single-reactor station, owned by the Tennessee Valley Authority, was listed at 44 percent of full power and ascending Wednesday, said John Moulton, a TVA spokesman.

"It is operating as it should," he said.

Tritium, a hydrogen isotope that boosts the explosive power of atomic bombs weapons, is required for every warhead in the U.S. arsenal.

This is a mission that had been considered for Hanford's Fast Flux Test Facility in the 1990s. The dormant FFTF needed multiple missions to justify restarting it. Tritium production would have used a significant portion of the reactor's capabilities.

However, in 1998, DOE decided to send the tritium production mission to the TVA's reactors in Tennessee and Alabama. In 2001, DOE decided to shut down the dormant FFTF. After some unsuccessful attempts to stop DOE, the shutdown began this year.

Since early September, TVA workers have been installing tritium-producing rods in the Watts Bar reactor while it was being refueled; the plant went back on line Monday night.

The government hasn't made tritium since 1988 when its production reactors at the Savannah River site in South Carolina were closed for operational and safety problems. Meanwhile, the short-lived material was recycled from older weapons.

The Energy Department will begin tapping into its five-year tritium reserve by 2005 without a new supply, although arms control needs could change that.