Source: Chattanooga Times Free Press | Dave Flessner | July 15, 2016

The TVA Watts Bar Nuclear Plant is seen Thursday, Oct. 22, 2015, near Spring City, Tenn., as Unit 2 begins producing electricity for the first time, 43 years after construction began at the site. (Credit: John Rawlston, Times Free Press.

The TVA Watts Bar Nuclear Plant is seen Thursday, Oct. 22, 2015, near Spring City, Tenn., as Unit 2 begins producing electricity for the first time, 43 years after construction began at the site. (Credit: John Rawlston, Times Free Press.)

The Tennessee Valley Authority this week completed a key performance test at its newest reactor at the Watts Bar Nuclear Plant, moving closer to bringing the first new American nuclear plant to commercial status in 20 years.

The Unit 2 reactor at Watts Bar, which first began limited power generation in May, was raised to 50 percent of its 1,150-megawatt generating capacity last week before plant operators conducted load rejection tests to dramatically swing power loads. During such tests, generation is raised and quickly lowered to simulate the potential of a storm-induced loss of transmission or off-site power or other plant accidents.

The newest Watts Bar unit was then taken off line Thursday during a planned power trip when the reactor was at 30 percent power.

“These tests are an opportunity to show that the reactor and the turbine can handle quick changes in power so that we can proceed on with our power testing,” TVA spokesman Jim Hopson said. “”All of the tests went like clock work and all of these tests worked exactly as designed. This was a major milestone to get to this point safely and to see the unit perform so well.”

TVA now will assess all of the data from this week’s tests before resuming power generation and additional power ascension testing, Hopson said.

TVA expects to bring the unit to full power and achieve commercial status for Watts Bar Unit 2 later this summer. Once that occurs, the reactor will generate enough power for about 650,000 homes and TVA will begin to amortize the $4.7 billion debt it incurred since TVA decided to revive the unit and finish it in 2007.

TVA began construction at Watts Bar in 1972 but suspended work in the 1980s due to employee safety concerns and a slowdown in the growth in power demand. Unit 2 at Watts Bar was about 80 percent complete at that time, but some of that work had to be redone and additional plant and equipment added to meet stricter safety standards adopted after the 2011 meltdown at the Fukushima Daiichi nuclear plant in Japan, which was partially destroyed by an earthquake and tsunami.

The new Watts Bar unit is the first new U.S. reactor to generate power for the electric grid since TVA finished the first reactor at Watts Bar in 1996.