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Watts Bar Unit 2

Today—Meeting Key Targets

The Watts Bar Unit 2 team continues to meet key targets for safety, quality, cost and schedule.

The project has completed four significant milestones:

  1. Completed hydrostatic pressure testing of the Unit 2 reactor coolant system, steam generators, and steam supply system.
  2. Assembled the nuclear reactor vessel.
  3. Conducted Open Vessel Testing, which verifies that safety-related systems inject water into the reactor vessel as designed.
  4. Constructed of one of the first functional FLEX equipment storage buildings in the industry.

Once operational, Watts Bar Unit 2 will produce the nation’s first new nuclear generation of the 21st century—low-cost, clean, carbon-free power.

March 2015—Preparations for More Critical Testing

Critical systems on Unit 2 are being readied for a major pre-operational milestone—hot functional testing. The unit will be brought up to operational temperatures and pressure without fuel in the reactor to ensure major systems important for making and moving the steam used to generate electricity will function together as designed. Important safety functions will also be tested.

Preparations include:

  • Energizing the main Unit 2 transformers and parts of the electrical distribution system
  • Using normal plant procedures to place systems and components that will be used during hot functional testing into the alignment that will be used for power operations
  • Confirming through testing the operability of motors, pumps, valves, circuits and other devices in nearly 60 systems

Hot functional testing will be conducted over a period of about 45 days during which Watts Bar systems will largely operate as a dual-unit nuclear plant for the first time.

February 2015—Major Regulatory Milestone

image of plant from the air

Watts Bar Nuclear Plant Unit 2 has cleared a major milestone toward becoming the nation’s first new nuclear generation of the 21st century. Based on detailed analysis and review, a key advisory group for the Nuclear Regulatory Commission has recommended the Commission approve the Watts Bar Unit 2 operating license, once TVA completes the remaining work and NRC inspections. The Advisory Committee on Reactor Safeguards made its recommendation after reviewing documents and inspections focusing on safety-related items.

January 2015—Control Rooms

The control rooms of both Watts Bar Unit 1 and Unit 2 are being made to support monitoring and control of many critical systems.

  • More digital links for monitoring allow operators to better respond to equipment or system issues
  • Upgraded control rooms that ensure little or no difference for operators training on the units

Upgrades to the Unit 2 control room also include the installation of more than 15 miles of new electrical wire, replacement of nearly 800 hand switches and reconfiguring more than 900 alarm indicators.

The control rooms will be essentially identical by the time Unit 2 comes on line.

January 2015—On Track for First New Nuclear

Watts Bar Unit 2 is on track to be the nation’s first new nuclear generation in the 21st century. Work at the project is building on proven technology, using established engineering and design standards, and a plant that was initially started in the 70s is being updated through a comprehensive refurbishment effort.

Scroll through these pages to see examples of systems, structures, and components that have been rebuilt or replaced using modern materials and current technology.

December, 2014—Cold Hydro Tests Complete

Another major milestone for the Watts Bar Unit 2 project is complete. Cold Hydrostatic Testing took place during three separate tests over several months—and verified that welds, joints, pipes and other components in the reactor coolant system, steam-supply system and associated high-pressure systems do not leak and will hold pressure.

image of employee stadning in front of equipment

The final pressure test was successfully conducted in mid-December. That test involved pressurizing the systems at above normal operating conditions, and set the stage to move these systems and components forward from construction to operation status.

image of two employees working

December 2014—Another Safety Milestone

Workers at Watts Bar Unit 2 continue to put safety first—and have now logged more than 30 million work-hours without a lost-time incident.

workers at Watts Bar

November 2014—Project on Track

  • The latest quarterly update to the Watts Bar Unit 2 Estimate to Complete covers the work accomplished between May and July 2014.
  • One year ago, the project was in final stages of bulk construction. There has been good progress since then as demonstrated by the focus on system specific construction work to support testing milestones and the successful completion of open vessel testing during the quarter.
  • The update validates that overall project targets continue to be met for safety, quality, cost, and schedule.

More details can be found in the update.

October 2014—TVA Meets with NRC Officials

On October 30, TVA nuclear leadership briefed the U.S. Nuclear Regulatory Commission in a public session at NRC headquarters in Rockville, Md. As part of the licensing process for Watts Bar Unit 2, TVA provided an update on key aspects of the Watts Bar project, including TVA’s ability to safely operate and maintain two units.

image of roundtable meeting

Prior to that meeting, NRC member Kristin Svinicki toured Watts Bar on October 22. While at the site, she was briefed on the work to complete Watts Bar Unit 2, transitioning Watts Bar to dual-unit operation, and integrating the dual-unit site into TVA’s nuclear fleet.

image of tour

Commissioner Svinicki’s visit is the fourth tour of Watts Bar Unit 2 by an NRC commissioner this year. The visits provide a first hand look at the completion project and how TVA is ensuring Unit 2 is being built safely, with quality and in a manner designed to ensure excellence in operation following licensing. 

October 2014—Cold Hydrostatic Testing

Watts Bar Unit 2 passes a major pressure test: Primary Cold Hydrostatic Testing, or Cold Hydro. By demonstrating that the systems and components that are central to nuclear operations can safely hold pressure above the normal operating value of 2250 psi, the team completed a major testing milestone. That’s puts Watts Bar Unit 2 one step closer to becoming the nation’s first new nuclear power generation of the 21st century.

September 2014—Safety Milestone

Safety is top priority at Watts Bar Unit 2. The team has logged more than 28.8 million hours without a lost-time incident.


August 2014—Reactor Vessel Is Assembled

The Watts Bar Unit 2 team safely completed the first and largest portion of assembling the reactor vessel: placing the core barrel into the reactor vessel. Inspections were performed at every stage as the 282,000-pound barrel was lifted and then lowered into the reactor. The entire lift process took approximately 12 hours to safely set up and complete—and was executed perfectly.

This was the first of three lifts that need to be completed to assemble the Unit 2 reactor for Cold Hydro, a pressure test that requires the reactor vessel to be assembled and tests the reactor coolant system and the high-pressure portions of the residual removal system, the steam generator and the chemical and volume control system and the safety injection system.

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July 2014—FLEX Buildings Mean Safety

Watts Unit Bar 2 is the the first nuclear plant in the U.S. to meet new Nuclear Regulatory Commission regulations established after the 2011 earthquake and tsunami that struck Fukushima Nuclear Plant in Japan. Watch the construction of one of the first functional FLEX buildings in the industry, complete with a 16-foot-tall tornado-proof door, designed to protect emergency equipment from missiles created in tornado situations, including flying cars.


July 2014—Open Vessel Testing

On July 1, 2014, Watts Bar Unit 2 completed Open Vessel Testing, which tests key safety and safety-support systems designed to deliver water to the reactor vessel. The time-lapse video below shows approximately 185,000 gallons of water flowing into the Watts Bar Unit 2 reactor vessel over a 23-minute period of testing.



Watts Bar team members now are reassembling the reactor in preparation for a second major testing milestone, Cold Hydro. This test verifies that welds, joints, pipes, components of the reactor coolant system and associated high-pressure systems meet quality standards.

June 2014—Cooling Tower Turned Over to Operations


TVA Field Engineer Alan Dawkins stands under the giant Watts Bar Unit 2 cooling tower.

Watts Bar Unit 2’s massive cooling tower was transferred from Nuclear Construction to Nuclear Operations, signaling its readiness for operations.

When a plant is operating, cooling water from the condenser is distributed through pipes and baffles inside the cooling tower and falls like rain about 60 feet, which cools the water before it is continuously recycled to condense more steam. Water in the vapor rising from the cooling tower is replenished to the condenser cooling system with water from the Tennessee River.


May 2014—Coolant System Ready for Testing

Watts Bar Unit 2 completed a significant amount of work to release the reactor coolant system to the site’s pre-operational startup engineering team after completing more than 192,000 craft hours and more than 1,200 work orders.

The system is the heart of the nuclear plant, constantly circulating highly pressurized water through the reactor, four steam generators, a pressurizer and the piping that connects them to the reactor. Inside the steam generators, the heat from the water coming from the reactor is transferred to a second separate supply of water that turns to steam that powers the turbine generator. See how Watts Bar Nuclear Plant uses steam to make power.

April 2014—Prepping for Testing

Engineers get an early jump on preparations for Open Vessel Testing, the first in a series of major milestones to lead Watts Bar Unit 2 to regulatory approval to load fuel. Open Vessel Testing ensures key safety systems and safety support systems work as designed to deliver water to the reactor vessel. Open Vessel Testing will culminate in water flowing into the reactor at about 10,000 gallons a minute.



April 2014—Operators Presented with Licenses

Eight nuclear professionals were formally presented with their Watts Bar Unit 2 operator licenses by Nuclear Regulatory Commission officials at an awards dinner in Cleveland, Tenn. The ceremony marked the licensed operators’ completion of 18 months of training and testing requirements.

new operators

Front row, Justin Gallagher, senior reactor operator; Lynne Parker, senior reactor operator; and Brent Henderson, senior reactor operator. Back row: Dave Gronek, Watts Bar plant manager; Sean Connors, Watts Bar senior manager for Operations; Eric Silvers, reactor operator; Thomas Heimel, senior reactor operator; Billy Horton, senior reactor operator; Craig Barger, senior reactor operator; Chris Church, Watts Bar site vice president; Mike Skaggs, senior vice president, Watts Bar Operations and Construction. Not pictured: Victor Bond, reactor operator.

January 2014—Shifting Gears

The focus of work on the Watts Bar Unit 2 is shifting from large-scale construction to completion and testing of individual plant systems.

image of workers at Watts Bar Unit Two

October 2013—Meeting Challenges

Safety and quality continue to be excellent as workers move toward delivering Watts Bar Unit 2 on time and within budget.

However, some challenges are arising, too. These include:

  1. Completing complex work and required documentation
  2. Performing testing on shared Unit 1 and Unit 2 systems without impacting the safe and reliable operation of Unit 1
  3. Addressing regulatory and licensing issues
  4. Successfully transitioning the site to dual-unit operations

July 2013—Review Yields Good News

The latest quarterly review of the Watts Bar 2 Estimate to Complete found:

  • Workers continued to deliver good safety performance.
  • Quality performance remained high, improving to 97 percent.
  • Overall, cost performance continued to be better than projected in the revised estimate to complete.
  • Schedule performance met expectations.
  • Challenges are anticipated as the as some systems move into testing mode, and others are completed.
  • No new risks emerged that currently compromise completion of the project; regulatory and licensing issues remain the primary concerns.

April 2013—Goals Exceeded

One year after the TVA Board approved the further construction of Watts Bar Unit 2, a quarterly review showed that the project continued to meet or exceed goals for quality, schedule and safety. 18 million work hours had been logged without a lost-time incident, and the overall quality acceptance rate was at 96 percent or better. However, despite the excellence, there will be challenges as the team works to deliver a safe, reliable unit.

February 2013—Moving the Vessel Head

Lifting an assembly made of 144 tons of carbon steel and precisely crafted control rods from a reactor vessel and moving it into a specially built holding stand and then putting it back again is a complex job. But the team achieved the right results and moved the 288,000-plus pound Watts Bar Unit 2 reactor pressure vessel head from its holding stand to the top of the reactor pressure vessel safely.

image of head lift

December 2012—Construction Moves Forward

The Watts Bar Unit 2 project focused on efficiently performing construction activities; maintaining the overall pace of installing commodities, such as valves, piping and cable; and continuing to implement improvement initiatives.

September 2012—Safety First

Building a nuclear plant is a complex task with lots of inherent safety hazards. But workers at Watts Bar Unit 2 recognize this, and by keeping safety first, surpassed 16 million work hours without an accident.

Watts Bar Unit 2 construction workers are demonstrating their commitment to keeping themselves and others safe by:

  1. Wearing the right personal protective equipment for every job
  2. Taking 2 minutes before they start work to identify potential hazards
  3. Immediately reporting potential safety issues and every injury so appropriate steps can be taken to prevent future injuries
  4. Intervening to protect each other from unsafe acts and to reinforce safe behaviors

Picture of welder

April 2012—Green Light for Watts Bar Unit 2

The TVA Board of Directors approved continuing the construction of Watts Bar Unit 2 with a revised estimate to complete of $4 billion to $4.5 billion. Estimates have it that the unit will be completed between September 2015 and June 2016. Once operational, Watts Bar Unit 2 will produce the first new nuclear generation in the United States—providing energy that is low-cost and carbon-free. When completed, Watts Bar Unit 2 will generate 1,150 megawatts of electricity—enough for about 650,000 homes in the Tennessee Valley.




Photo Album

Scroll through these pages to see examples of systems, structures, and components that have been rebuilt or replaced using modern materials and current technology.



Quarterly Updates (PDF)

Tenth Quarterly Update

Ninth Quarterly Update

Eighth Quarterly Update

Seventh Quarterly Update

Sixth Quarterly Update

Fifth Quarterly Update

Fourth Quarterly Update




Estimate to Complete

Executive Final Report on the Estimate to Complete analysis (4.2 mb, PDF)




What does it take to make a nuclear plant?

Along with a lot of skill and effort, it takes lots of space, a proven design and plenty of safe reliable equipment.

Here are the vital statistics about Watts Bar Unit 2.

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