The Tennessee Valley Authority approved a plan today to produce nuclear weapons material in a commercial reactor for the first time in U.S. history, breaching a long-standing wall between civilian and military nuclear power.

The TVA board voted 3 to 0 to allow the Watts Bar Nuclear Plant to produce tritium as early as 2003, while continuing to make electricity for TVA.

The agreement between TVA and the Energy Department angered peace activists, who said using a civilian reactor to make tritium runs counter to U.S. efforts to get other countries to reduce nuclear weapons.

"They're watching what we do, not listening to what we say," said Ralph Hutchison of the Oak Ridge Environmental Peace Alliance.

Although the U.S. government has urged other countries to avoid such dual military-civilian use of their nuclear reactors, Russia and Canada do so, said Energy Department spokesman Matthew Donoghue.

TVA officials pointed to a 1998 interagency report to Congress that concluded no international laws or agreements would prohibit the production of tritium, a hydrogen isotope that enhances the explosive power of nuclear warheads.

TVA, the nation's largest public power producer, was picked by the Energy Department a year ago to be the government's new source for tritium.

The Energy Department has not produced any new tritium since it closed its production reactors at the Savannah River Site in South Carolina in 1988. It has been recycling tritium out of retired weapons since then.