TVA operates Watts Bar 2 under own power for first time

Licensed reactor operators at the Tennessee Valley Authority (TVA) 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, carbon-free electricity as the nation’s first new nuclear unit in the 21st century, TVA said in a May 23 news release.

The Nuclear Regulatory Commission (NRC) reactor status reported on May 23 still listed the reactor at zero generation.

The recently-completed 1,150-MW pressurized water reactor (PWR) unit is expected to achieve commercial operation in summer 2016 at a total estimated project cost of $4.7bn, TVA said in a recent update posted on its website. That’s within the range approved by the TVA Board earlier this year, TVA has said.

“This milestone is the result of the hard work by Watts Bar employees supported by the entire TVA nuclear team,” said TVA 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. 

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%, TVA said. 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 MW of baseload 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, TVA said.

About Wayne Barber 4201 Articles
Wayne Barber, Chief Analyst for the GenerationHub, has been covering power generation, energy and natural resources issues at national publications for more than 20 years. Prior to joining PennWell he was editor of Generation Markets Week at SNL Financial for nine years. He has also worked as a business journalist at both McGraw-Hill and Financial Times Energy. Wayne also worked as a newspaper reporter for several years. During his career has visited nuclear reactors and coal mines as well as coal and natural gas power plants. Wayne can be reached at