Watts Bar 2 steam generator replacement completed

09 November 2022

Unit 2 of Tennessee Valley Authority's (TVA's) Watts Bar nuclear power plant has returned to service following the completion of a project to replace all four of its original steam generators.

One of four steam generators at Watts Bar 2 being removed for replacement (Image: Framatome)

The replacement of the unit's steam generators was performed by the Steam Generating Team (SGT) - a joint venture formed in 1991 between Framatome and United Engineers & Constructors Inc to provide heavy component replacement services and other major projects to the nuclear industry.

Steam generators serve as heat exchangers in pressurised water reactors (PWRs). These components use the heat generated by the reactor to create steam that drives the turbines, which turns a generator and creates electricity.

To remove and replace the 20-metre, 360-tonne steam generators through the reactor building, temporary openings in the reactor building dome, containment and steam generator enclosures were required. Precision measurements utilising meticulous metrology practices, along with optimised 3D fit-up solutions and specialised machining enabled SGT to precisely place the replacement steam generators back into the existing plant configuration.

"This project, like many others performed by SGT, utilised our experienced team and proven processes customised for steam generator replacement," said SGT President Art Lembo.

"We are very happy to have performed a significant role for TVA in their investment in the life extension of the Watts Bar plant and its role in providing carbon-free, reliable power to the Tennessee Valley," said United Engineers & Constructors CEO Scott Reeder. "At United, our mission is to partner with our clients to deliver innovative and transformative infrastructure designed and built to meet the demands for today and for the future. As such, we are committed to continued support of nuclear technology as it takes its place in environmentally responsible carbon-free power supply."

Watts Bar, near Spring City, Tennessee, is home to two nuclear reactors. Construction of both units first began in 1972, but was suspended in 1985. TVA subsequently decided to resume work on unit 1, which started up in 1996. In 2007, the authority took the decision to complete Watts Bar 2, which had been about 55% complete when construction was suspended. The 1165 MWe (net) PWR reached first criticality in May 2016, was synchronised to the grid the following month and entered commercial operation in October 2016.

In February 2020, Framatome announced that TVA had awarded it several multimillion-dollar contracts for work across the company's reactor fleet. This included fuel for the Browns Ferry nuclear power plant, fuel handling equipment upgrades across the fleet and steam generator replacements at Watts Bar 2.

"Removing all four of unit 2's original steam generators and installing the four upgraded models ... is a significant engineering and operational project that our team completed safely and successfully," said Tony Williams, Watts Bar site vice president. "Along with the new, more efficient steam generators, our team completed numerous maintenance activities that have the unit ready for its next 18-month cycle of reliable and affordable carbon-free power generation for the 10 million people across the region who count on reliable energy every day."

The original steam generators on Watts Bar 1 were replaced in 2006.

Researched and written by World Nuclear News