Watts Bar nuclear plant.

Less than two days after a transformer fire forced TVA's newest reactor to shut down, the other reactor at the Watts Bar Nuclear Plant was also shut down today to help plant workers perform needed tests and equipment repairs in the switchyard following the Tuesday night blaze.

TVA spokesman Jim Hopson said the Unit 1 reactor at Watts Bar was idled to allow plant workers to safely assess the main bank transformers and other equipment without the switchyard being energized with electricity.

"The safest way to do the assessment we need to do is to de-energize the switchyard and the only way to that is to take the unit off line," Hopson said. "We wanted to ensure the safety of our employees while they do this necessary work."


Hopson said TVA hopes to complete the evaluation and to be able to restart the Unit 1 reactor "within a few days." But in the meantime, TVA is getting no power from either reactors at Watts Bar even as summertime temperatures keep power demand relatively high in the Tennessee Valley.

It is unclear when TVA may be able to restart its Unit 2 reactor.

During high-demand periods, TVA generates nearly $1 million a day worth of power from each of its nuclear units.

TVA was in the midst of a series of power ascension tests on its new Unit 2 reactor on Tuesday when a fire erupted in a main bank transformer on the non-nuclear side of Watts Bar. The fire triggered a trip of the Unit 2 reactor, which was operating at about 99 percent of its rated 1,150-megawatt capacity at the time.

TVA and Nuclear Regulatory Commission crews are still evaluating the cause of the fire and any corrective actions TVA needs to take to ensure the safety of the plant when it resumes power generation. The fire-damaged transformer will be replaced with one of the spare units on site at Watts Bar, Hopson said.

TVA began limited power generation from the Unit 2 reactor at Watts Bar in May. The unit is the first new reactor added to America's power grid in 20 years. But the newest unit has not yet achieved full power and has yet to officially be declared a commercial reactor and brought into TVA's rate base.

That achievement, which TVA said earlier this year should occur by June, now appears unlikely until next month at the earliest. That will push the start of the capital recovery for the $5 billion reactor into fiscal 2017.