SPRING CITY, Tenn. – Licensed reactor operators at Tennessee Valley Authority’s Watts Bar Unit 2 project reached a major milestone at 2:16 a.m. EDT, Monday, May 23, 2016, when the unit’s reactor achieved its first sustained nuclear fission reaction.

Also known as achieving “initial criticality,” Unit 2 is now generating heat under its own power and will soon be producing safe, carbon-free electricity as the nation’s first new nuclear unit in the 21st century.

“This milestone is the result of the hard work by Watts Bar employees supported by the entire TVA nuclear team,” said Chief Nuclear Officer Joe Grimes. “While this achievement is important, safety remains our top priority and we will now move forward with fully integrating the seventh unit into the fleet with that focus in mind.”

Like its sister, Unit 1, Watts Bar Unit 2 is designed to produce electricity by using controlled nuclear fission to generate heat, which is then used to produce steam to turn turbines and a single, large generator.  More information about this process can be found on TVA’s Watts Bar webpage.

The reactor is now operating in a stable condition at low power levels.  During the coming weeks, power levels will be slowly increased as part of scheduled power ascension testing and the unit will begin producing electricity that will flow onto TVA’s transmission system.

Plant systems and controls will be monitored and tested at various power levels up to 100 percent. These tests will be repeated multiple times to ensure the entire system operates safely as designed.

Once all tests have been completed successfully, the unit will provide a sustained 1,150 megawatts of safe, low-cost, reliable, carbon-free electricity to the Tennessee Valley. Combined with Watts Bar Unit 1, the plant will supply power to roughly 1.3 million homes in the TVA service area.

The Tennessee Valley Authority is a corporate agency of the United States that provides electricity for business customers and local power distributors serving more than 9 million people in parts of seven southeastern states. TVA receives no taxpayer funding, deriving virtually all of its revenues from sales of electricity. In addition to operating and investing its revenues in its electric system, TVA provides flood control, navigation, and land management for the Tennessee River system and assists local power companies and state and local governments with economic development and job creation.