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Watts Bar Cooling Towers

Watts Bar Unit 2: What It Means for You

Achieving commercial operation of Watts Bar Nuclear Plant’s Unit 2 was a major achievement for TVA, and a smart investment for every energy consumer in the Tennessee Valley. Here’s why.

In October 2016, we announced some very big news, long in the making: Watts Bar Nuclear Plant’s Unit 2 is online and in commercial production. This is the result of tens of millions of safe man hours of work. It is the culmination of nearly two years of rigorous plant testing. It is the first new nuclear power to join the American energy grid in the 21st century. And it generates enough energy to power 650,000 homes.

But for average consumers, it might raise a few questions. How does it work? Why was it necessary? And how does it benefit the Tennessee Valley electric consumer?

In other words, what’s the hoopla all about, and what’s in it for you? Allow us to explain.

How It Works

The simplest answer? It generates steam.

How it produces steam is a little more technical. The process of creating power using nuclear energy begins with the splitting of atoms in a process called fission, which produces heat. This happens inside a sealed reactor filled with water that is pressurized so that the water cannot boil.

This super-heated water is piped from the reactor to a steam generator, where it transfers its heat to a second separate loop to boil water and create steam. (The primary water—still contained and pressurized—is then piped back into the reactor to be reused.)

The steam, which is not radioactive, is then used to spin turbines that drive the generator to produce electricity—lots of it. Watts Bar Nuclear Plant Unit 2 produces 1,150 megawatts of power for the Tennessee Valley.

The steam used to spin the turbines is converted back to water in the condenser using a third “cooling” loop. This third loop includes the iconic concave cooling towers (that’s steam, not smoke, billowing from the top) that efficiently remove heat as cooling water is continuously circulated.

”Nuclear generation uses the same generation principles as most other TVA plants, but because of our powerful, efficient nuclear fuel, we can produce more around-the-clock, low-cost electricity than other sources,” said Watts Bar site vice president Paul Simmons. “Day in and day out, TVA’s seven nuclear units are providing more than 35 percent of the power being used by 9 million electric consumers.”

To see for yourself how Watts Bar Nuclear Plant works, click here.

Safety—TVA’s Overriding Priority

Safety is our overriding priority at TVA, and each of our seven nuclear units has multiple redundant systems in place to keep the public, our employees and the communities that surround our plants safe. Safety features include experienced, highly-trained nuclear professionals; multiple layers of physical containment barriers that protect the reactor; and numerous automatic and manual safety systems and controls designed to shut down the plant if necessary. This defense in depth maintains nuclear safety even in the most unlikely of events.

The nuclear industry is one of the most highly tested and regulated in the U.S. Our plants operate with oversight from the Nuclear Regulatory Commission (NRC), which has full-time inspectors stationed at each of our plants.

All U.S. plants are well designed to withstand natural disasters such as floods, earthquakes and hurricanes, as well as man-made threats such as plane crashes. After the Fukushima event in Japan, the NRC required all nuclear plants to install additional backup safety equipment—known as FLEX—to protect plants from even more extreme events, or “stacked” events, in which one disaster follows another.

Watts Bar Units 1 & 2 were the first in the county to meet new NRC FLEX requirements.

Why It Was Necessary

As TVA looks toward the future, we are planning to reduce our carbon footprint. In fact, by the year 2020, TVA’s generating resources will emit 60 percent less carbon than in 2005. This means we will be moving away from dependence on high-carbon-emitting fossil fuels and adding more clean generation to the power portfolio.

In 2015 and 2016, TVA closed Widows Creek Fossil Plant and Colbert Fossil Plant, which together had a generating capacity of 2,800 MW and were instrumental in helping provide TVA’s base load—that amount of power that is always “on” and available to help meet the region’s minimum and continuous demand for energy.

Gone are the emissions associated with those two plants; gone too are the megawatts they produced.

Clean nuclear power is the ideal replacement for this lost baseload. It is, by its very nature, always on—together with Unit 1, Watts Bar Nuclear Plant now reliably produces 2,300 MW of baseload energy, enough power 1.3 million homes in the Tennessee Valley day and night.

According to Joe Grimes, TVA executive vice president of Generation and chief nuclear officer, Watts Bar Unit 2 is a vital investment in the Valley’s clean energy future. “Nuclear power remains the only source of carbon-free energy that is available 24 hours-a-day, seven days-a-week,” he says.


The benefits of nuclear power are many, and include:

  • Clean air. Nuclear power is clean power. There is no carbon involved; there are no emissions. It’s a simple equation: More nuclear power and less fossil power equals cleaner air for the Tennessee Valley.
  • Reliability. Nuclear power stays on 24/7 producing low-cost, reliable power for homes and businesses.
  • Low rates. Granted, building a nuclear unit requires great capital investment—Watts Bar Unit 2 met its budget of $4.7 billion. However, the power it produces is inexpensive, second only to hydro in affordability. Having additional nuclear energy on line will help TVA meet its commitment to keep costs as low as is feasible.
  • Economic development. Reliable clean energy at a low cost is the right mix for attracting businesses and industries increasingly competing on the strength of their carbon footprint—which necessarily includes the power they buy. More business and industry means more jobs for our region.

On the day Unit 2 went commercial, TVA president and CEO Bill Johnson put it this way: “TVA’s mission is to make life better in the Valley by providing reliable low-cost energy, protecting our area’s natural resources and working to attract business and growth—all priorities simultaneously supported by the completion of Watts Bar Unit 2.”

Johnson pointed to the economic development aspect as perhaps the number one benefit. “Watts Bar Unit 2 is a key part of our commitment to produce cleaner energy without sacrificing the reliability and low cost that draws both industry and residents to our area,” he said.

The final word? “It’s a great day for TVA and for the people of the Tennessee Valley.”