Work is in progress this fall at TVA's Sequoyah Nuclear Plant to replace the four steam generators in Unit 2.

In the TVA video (below) is the assembly of the Platform Twin-Ring Containerized Crane (red crane on left of screen). This crane is more than 380 feet tall. It will be used to make 22 heavy lifts, including sections of reactor shield building dome that are expected to weigh about 160 tons each, two steel containment vessel sections weighing about 16 tons each, four 65-ton sections of the concrete enclosures surrounding the steam generators, and the four old steam generators and the four new steam generators, each of which weighs about 345 tons.

The replacement steam generators were designed by Westinghouse, fabricated by Doosan, and SG tubes provided by Sandvik.

Design features of the new RSGs:

  • Same physical size as existing steam generators
  • Increased tube surface area to provide additional plugging margin
  • Integral loose parts strainer provided for FW/AFW
  • Reduced moisture content at steam nozzle exit
  • Additional access hand holes for maintenance
  • Snaplock Nozzle Dams provided for dose reduction
  • Electro Polished Head Bowls for dose reduction

Major Activities Involve in this steam generator replacement:

  • Defuel Reactor
  • Cut holes in Shield Building dome, SCV, and SG Compartment Roof
  • Remove existing SGs
  • Install Replacement SGs
  • Restore SG Compartments, RCS piping, SCV, and Shield Building dome
  • Refuel Reactor
  • Pressure Test to Demonstrate Restored Containment Integrity

On November 6, the first steam generator (#3) was lifted using the Platform Twin-Ring Containerized Crane (TVA picture below).