Bechtel, the company constructing the Vogtle Electric nuclear plant in Waynesboro Georgia have reached a construction milestone when they set into place a passive containment cooling water tank. According to the company, that is the last major lift at the two-unit nuclear power plant, which is operated by Southern Nuclear, a subsidiary of Southern Co. The Vogtle plants’ Units 3 and 4 are the only two nuclear power plants under construction in the U.S. Bechtel said it has had more than 7,000 workers on the jobsite, which, counting the permanent jobs that have been created, makes Vogtle the largest jobs-producing construction project in the state of Georgia.
Bechtel has performed both the construction and engineering for more than 80% of the nuclear plants in the United States. Brian Reilly, project director for Bechtel, said setting the tank in place represents the topping out of Unit 4’s shield building. The passive containment cooling water tank measures 35 feet tall and has an 85-foot outer diameter. The tank module, which includes outfitting and rigging, weighs 360 tons. The company said the AP1000 plant’s passive safety systems require no operator actions to mitigate potential emergency situations, because they use only natural forces such as gravity, natural circulation and compressed gas to achieve their safety function. No pumps, fans, diesels, chillers or other active machinery are used, except for a few simple valves that automatically align and actuate the passive safety systems.
The tank will hold approximately 750,000 gallons of cooling water ready to flow down into the containment vessel in an emergency to help cool the reactor, even if external power is lost. The water can also be directed to top off the spent fuel pool, while the tank itself can be refilled from water stored elsewhere on site.