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Watts Bar Unit 2

Work to complete Watts Bar Nuclear Plant Unit 2 continues to meet targets for safety, quality, cost, and schedule. The project recently completed three significant accomplishments:

  • A major testing milestone of key safety systems called Open Vessel Testing
  • Assembly of the nuclear reactor vessel
  • Construction of one of the first functional FLEX emergency equipment storage buildings in the industry.

Once operational, Watts Bar Unit 2 will produce the first new nuclear generation of the 21st century in the United States — generation that is low-cost and carbon-free.


Several members of TVA’s Regional Energy Resource Council (RERC) recently toured Watts Bar, learning firsthand how completing Watts Bar Unit 2 will add to the Tennessee Valley’s energy diversity, sustainability, and reliability. The group saw the core barrel that was placed inside the vessel during the recent reactor assembly.


Recent Progress

Open Vessel Testing was the first of several Watts Bar Unit 2 major testing milestones to be completed. 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 on July 1, 2014.


Following the completion of full flow Open Vessel Testing, the Watts Bar team fully assembled the reactor vessel for the first time toward the goal of loading fuel and achieving commercial operation by December 2015. This process included safely lifting three major components into place: the core barrel, the upper assembly (which houses the control rods), and the 298,700-pound reactor head.  See the team moving and inspecting the reactor components in this time-lapse video:

With the reactor assembled, the team is preparing for a second major milestone test, Cold Hydrostatic Testing. Cold Hydro verifies that welds, joints, pipes, components of the Reactor Coolant System and associated high-pressure systems meet quality standards.

When completed Watts Bar Unit 2 will generate 1,150 megawatts of electricity — enough for about 650,000 homes.


The Watts Bar Unit 2 team has worked more than 28 million hours without a lost-time incident.


Watts Bar Unit 2 will be 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.


Big Move

Crews work to install huge 28-inch thick, 47-ton concrete and steel doors at Watts Bar Nuclear Plant. The doors are part of a building to protect emergency diesel generators that provide backup electricity for the plant. The building is designed to withstand 360 mile-per-hour winds and flying debris.



Quality of work remains high with a quality control acceptance rate greater than 97 percent in July 2014. In the coming months, additional tests and inspections will ensure that Unit 2 systems operate as designed and that the unit is ready to begin generating electricity for the Tennessee Valley in late 2015.

Cost and Schedule

The revised Watts Bar Unit 2 Estimate to Complete included additional funding of $1.5 billion to $2 billion; the total cost for completing the unit is expected to be between $4 billion and $4.5 billion. The most likely completion date for Watts Bar Unit 2 is December 2015.  Additional cost and schedule information is available in the Watts Bar Unit 2 Eighth Quarterly Update to the Estimate to Complete.


As with any complex project, there are challenges and risks associated with completing Watts Bar Unit 2. The team is prepared with a plan to identify, assess, and address challenges and risks as they arise. Challenges include:

  • Completing complex work while protecting safe and reliable operation of Unit 1, the operating unit
  • Completing systems for pre-operational testing during a compressed time period while maintaining safety and quality standards
  • Preparing for upcoming testing milestones
  • Addressing emergent work during testing activities

Regulatory and licensing issues remain the primary risk for the project.


View previous Watts Bar Unit 2 updates

TVA's confidence in the new completion schedule

TVA has high confidence in the new completion schedule and cost estimates for Watts Bar Nuclear Plant Unit 2.

The estimate to complete — called the ETC —  was prepared in collaboration with TVA’s construction contractors and outside experts. The ETC includes:

  • A root-cause analysis of factors that took the project off track
  • A detailed estimate of the costs and time needed to complete the remaining work
  • Estimates for the amount of materials (e.g., conduit, cable, piping) still to be installed, support activities (e.g., scaffolding, painting) and labor rates

Why TVA needs more nuclear power

Nuclear is the best technology for keeping reliability high and rates competitive. It is cleaner than coal and produces no harmful greenhouse gases. And while expensive and complicated to build, nuclear units are economical to operate.

Industry-wide, nuclear is second only to hydroelectric in low production, fuel, and operations and maintenance costs.

By increasing nuclear generation, pursuing renewable energy sources and promoting energy efficiency, TVA will rely less on coal, continue steady progress in reducing air emissions and provide reliable, economical power for the people of our region.

How Watts Bar 2 will help

Completing Watts Bar 2 will put an existing asset to work for TVA customers and add more than 1,150 megawatts of safe, clean, reliable and economical base load generating capacity to the TVA power system.

Watts Bar 2 will help meet the demand for electricity in the Tennessee Valley, with low-cost, carbon-free electricity. It will help replace older, more costly and less efficient coal units that are being retired.

One nuclear unit can make as much electricity as five to 10 coal units without carbon emissions. It is estimated that Watts Bar 2 will help TVA avoid coal-fired emissions of 6 million to 8 million tons of carbon dioxide a year.

Vital statistics about Watts Bar Unit 2

Plant site

  • Location: Near Spring City in southeastern Tennessee
  • Acreage: 1,700-acre site on Chickamauga Reservoir

Cooling towers

  • Quantity: 2
  • Height: 506 feet
  • Diameter: 405 feet at ground level
  • Water flow: 410,000 gallons per minute


  • 500,000-volt transmission lines: 5
  • 161,000-volt transmission lines: 2

Plant design

  • Westinghouse pressurized water reactor that is expected to generate 1,150 megawatts (summer net capability)
  • Reactor core holds 193 fuel assemblies, each containing 264 fuel rods

Reactor vessel

  • Height: 43.8 feet
  • Weight: About 265 tons (empty)
  • Inside diameter: 14 feet
  • Steel thickness: About 9.4 inches
  • Operating temperature: About 586 degrees Fahrenheit
  • Operating pressure: About 2,235 pounds per square inch

Primary containment

  • Inside height: 197.3 feet
  • Inside diameter: 115 feet
  • Steel inner thickness: 1 inch
  • Design pressure: 15 pounds per square inch

Steam generators

  • Quantity: 4
  • Height: 67 feet 8 inches
  • Weight: About 380 tons
  • Operating temperature: About 600 degrees Fahrenheit
  • Operating pressure: 1,000 pounds per square inch

Main generator

  • Height: 16 feet
  • Length: 40 feet
  • Stator weight: About 1,000 tons
  • Rotor weight: About 200 tons
  • Ratings: 1,411 megawatts, 24,000 volts
  • Speed: 1,800 rotations per minute

Steam turbines

  • High pressure: A single eight-stage double-flow axial turbine
  • Low pressure: A series of three, eight-stage double-flow axial turbines
  • Maximum blade diameter: 16 feet
  • Rotor weight: About 177 tons

Main condenser

  • Tubes: About 27,410
  • Tube length: About 115 feet
  • Tube diameter: 1 inch


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