Skip to main content.

News Center

Vogtle Unit 4 shield building roof set

December 11, 2020

The two-million-pound roof of the Vogtle Unit 4 shield building has been set into place at Georgia Power's nuclear expansion project near Waynesboro, Georgia. With this placement, there is now one last major crane lift remaining for Vogtle Unit 4, the CB-20 module, which is part of the AP1000 reactor's advanced passive safety system.

The Vogtle Unit 4 shield building roof placement comes just days after the receipt of the first nuclear fuel shipment for Vogtle Unit 3, representing the first nuclear fuel shipment for the AP1000 reactor in the U.S.

With the receipt of the first nuclear fuel assemblies, the site is preparing for the last major test remaining for Unit 3, hot functional testing, ahead of initial fuel load. This series of tests is the last critical step before fuel load and ultimately in-service operation for Unit 3.

The Unit 4 shield building roof measures 135 feet in diameter, 37 feet tall and weighs more than two fully-loaded jumbo jets. This placement follows the setting of the Unit 4 containment vessel top from earlier this year. The shield building is a unique feature of the AP1000 reactor design for Vogtle 3 & 4, providing an additional layer of safety around the containment vessel and nuclear reactor to protect the structure from any potential impacts. 

2020 Milestones Achieved

  • Completion of Cold Hydro Testing for Unit 3 – Confirmed the reactor's coolant system functions as designed and verified the welds, joints, pipes and other components of the coolant system and associated high-pressure systems do not leak when under pressure.
  • Emergency Preparedness Drill – Vogtle 3 & 4 completed a required emergency preparedness exercise for a simulated emergency event for Vogtle Unit 3. Teams participated in the simulation and demonstrated their ability to effectively and efficiently respond and protect the health and safety of the public.
  • Vogtle 3 & 4 Operators Receive Licenses – The Nuclear Regulatory Commission (NRC) issued the first operator licenses to 62 Reactor and Senior Reactor Operators for Vogtle 3 & 4. To receive a nuclear operator license from the NRC, license holders must demonstrate they possess the required knowledge, skills and abilities to safely and effectively operate the plant.
  • Completion of Closed Vessel Testing – The completion of this milestone prepared Unit 3 for cold hydro testing. Closed vessel testing verified the pipes and valves in the Unit 3 reactor coolant system were installed as designed and helped ensure safety systems function properly.
  • Completion of the Structural Integrity Test and Integrated Leak Rate Test – Both tests were completed in succession and demonstrated the Unit 3 containment vessel meets construction quality and design requirements.
  • Placement of the final module for Unit 3 – The water tank that sits atop the containment vessel and shield building roof, known as module CB-20, is a major part of the AP1000 reactor's advanced safety system and will hold approximately 750,000 gallons of water ready to flow down in the unlikely event of an emergency to help cool the reactor.
  • Placement of the Unit 3 integrated head package (IHP) atop the reactor vessel – Standing 48 feet tall, weighing 475,000 pounds and containing more than three miles of electrical cables, the IHP will eventually be used by highly-trained nuclear operators to monitor and control the nuclear reaction that will occur inside the Unit 3 reactor vessel.
  • Completion of Open Vessel Testing for Unit 3 – This successfully demonstrated how water flows from the key safety systems into the reactor vessel ensuring the paths are not blocked or constricted, and confirmed the pumps, motors, valves, pipes and other components of the systems function as designed.
  • Placement of the polar crane and containment vessel top for Unit 4 – This signified that all major lifts inside the containment vessels for both units are complete.

With more than 7,000 workers on site, and more than 800 permanent jobs available once the units begin operating, Vogtle 3 & 4 is currently the largest jobs-producing construction project in the state of Georgia.

Photos Highlight Progress

Follow the progress being made at the site of the nation's first new nuclear units in more than 30 years through the Plant Vogtle 3 & 4 Online Photo Gallery and Georgia Power's YouTube channel.

About Georgia Power
Georgia Power is the largest electric subsidiary of Southern Company (NYSE: SO), America's premier energy company. Value, Reliability, Customer Service and Stewardship are the cornerstones of the company's promise to 2.6 million customers in all but four of Georgia's 159 counties. Committed to delivering clean, safe, reliable and affordable energy at rates below the national average, Georgia Power maintains a diverse, innovative generation mix that includes nuclear, coal and natural gas, as well as renewables such as solar, hydro and wind. Georgia Power focuses on delivering world-class service to its customers every day and the company is recognized by J.D. Power as an industry leader in customer satisfaction. For more information, visit and connect with the company on Facebook (, Twitter ( and Instagram (

COVID-19 Updates

As the coronavirus continues to spread, Georgia Power wants to assure our customers that we have comprehensive plans in place to continue our operations.

Vogtle News

See how we're doing our part to help secure America's energy future.

View Vogtle News