The Tennessee Valley Authority has begun a refueling and maintenance outage at Browns Ferry-2 that includes the largest scope of turbine deck work since the unit’s construction, as well as innovations in fuel assembly components, the utility announced on March 1.
On deck: All three of the 1,254.7-MWe boiling water reactor’s low-pressure turbines will undergo a comprehensive replacement of major components, including new rotors, inner casings, steam piping and bellows, and turbine supervisory instruments, requiring the support of more than 500 additional outage workers. TVA said that 600 crane lifts will need to be performed for some components, such as the rotors, which weigh up to 327,888 lb., and inner casings, which weigh up to 200,000 lb.
According to TVA, once the Browns Ferry-2 turbine project is complete, the unit will generate an estimated 7 additional megawatts of electricity, enough to power more than 4,000 additional homes.
“TVA’s investment in Browns Ferry and the infrastructure of our power systems ensures that we can continue to provide reliable power for our local power companies and communities when they need us most,” said Matt Rasmussen, Browns Ferry’s site vice president.
Meanwhile: As workers upgrade the turbine deck, the outage refueling team will load four new 3D-printed fuel assembly brackets in the reactor. The brackets, or, more specifically, channel fasteners, are the first of their kind to be loaded into a commercial reactor, according to TVA. They were manufactured at Oak Ridge National Laboratory in a joint project with the utility and its fuel supplier, Framatome, as part of the lab’s Transformational Challenge Reactor Program.
After the brackets are loaded, they will remain in the reactor for six years, with inspections planned during outages and after use.
Dan Stout, TVA’s director of nuclear technology innovation, said, “Being the first to use these additively manufactured components supports an innovative manufacturing approach that could pave the path for use across the existing nuclear fleet and in advanced reactors and small modular reactors.”