The final tab for getting the Watts Bar Unit 2 nuclear generator back in shape to produce power for homes and businesses and irradiate tritium for U.S. nuclear weapons will be about $600 million, the Tennessee Valley Authority said Monday in a regulatory filing.
On July 1, the Tennessee Valley Authority (TVA) finished installing four new steam generators for the Watts Bar Unit 2 reactor, which was also refueled at that time following a roughly four-month outage that began in March. TVA had expected to finish the installation in May, but unspecified issues with the generators and bad weather complicated things, the authority said at the time.
Under an interagency agreement, Watts Bar Unit 2 began irradiating tritium for the Department of Energy’s National Nuclear Security Administration (NNSA) in 2021, joining Watts Bar Unit 1, which has irradiated tritium for U.S. nuclear weapons since 2003. The radioactive hydrogen isotope decays relatively rapidly and must be replaced regularly to keep the weapons at their designed destructive power.
Almost as soon as Watts Bar 2 started producing tritium, the reactor suffered from a string of bad luck and had as of Tuesday yet to reach its target tritium output. TVA has long known that Watts Bar 2 would need new generators this decade, but the authority had hoped to put off the installation until 2023. Instead, after a refueling outage in 2021 revealed the extent of the degradation to the generators, TVA wound up taking the reactor offline early.
In a 10-Q filing with the Securities and Exchange Commission, TVA said the bill for the new generators came to $548 million as of June 30, with another $47 million in expected expenses left for 2022.
NNSA is ramping up tritium production at the power plants — presently the weapons program’s only source of the relatively rapidly decaying, radioactive hydrogen isotope — to cope with the looming demands of the five major nuclear-weapon refurbishments scheduled for this decade. NNSA wants the two plants to produce 2,800 grams of tritium per cycle starting in fiscal year 2025, which begins Oct. 1 — substantially more than earlier estimates.
In an emergency, TVA’s Sequoya reactors could also be used to produce tritium, though TVA in its latest 10-Q said it “does not have plans to employ Sequoyah units for tritium production in the near term.” The agency has used that language, or similar language, for about the past seven years. Prior to that, according to a 10-K filing from 2015, the agency thought it could “meet the DOE and the DOD [Department of Defense] tritium requirements using Watts Bar Unit 1 while maintaining Sequoyah reactors as backups.”
