The Obama administration said this week it planned to increase tritium supplies for the U.S. nuclear stockpile by producing the radioactive gas at the Tennessee Valley Authority’s two-unit Sequoyah nuclear plant as well as at TVA’s Watts Bar plant.

The plans were revealed in the fine print of the fiscal year 2011 budget proposal of the National Nuclear Security Administration (NNSA), the semi-autonomous agency within the Energy Department that operates the U.S. nuclear weapons complex.

Tritium, which boosts the explosive power of nuclear warheads, has been produced at Watts Bar since October 2003. DoE switched to using the federal power agency’s reactor after aging tritium production reactors at its Savannah River Site in South Carolina were shut down in 1988 due to safety issues.

The use of the TVA reactor has been controversial among nonproliferation groups because it adapts a commercial power reactor for weapons purposes. The U.S. government strongly opposes use of commercial reactors for weapons production in other countries as a proliferation risk.

However, tritium must be replenished in warheads periodically because the gas decays relatively quickly, having a half-life of about 12 years.

The NNSA budget plan said additional tritium production in the Sequoyah reactors was needed to meet stockpile requirements approved by President Obama.

“Plans are being initiated to bring additional production capacity on line using TVA’s Sequoyah Unit 1 and 2 reactors to meet tritium production requirements specified in the nuclear weapons stockpile plan signed annually by the president,” the budget document said.

The document said production would continue at Watts Bar in fiscal 2011, which starts in October, and plans were to insert tritium-producing rods in the Sequoyah Unit 1 reactor in fiscal 2012.

Other federal documents show NNSA ramped up processing of warhead tritium reservoirs over the last year, with the number of reservoirs filled or emptied at Savannah River’s Tritium Extraction Facility increasing by 25 percent in fiscal 2009 over fiscal 2008 levels.