Dive Brief:

• Bechtel achieved a major construction milestone at the Vogtle Electric Generating Plant near Waynesboro, Georgia, last week when it set into place a passive containment cooling water tank. This, according to Bechtel, is the last major lift at the two-unit nuclear power plant, which is operated by Southern Nuclear, a subsidiary of Southern Co.
• 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 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 either the construction or engineering for more than 80% of the nuclear plants in the U.S.

Dive Insight:

Bechtel said the first of 1,485 major unit modules arrived on the Vogtle site in 2011, while the last reached the project in 2019. All modules were manufactured offsite and arrived at the project ready to be assembled into larger modules that make up each of the two units. The modules included plant components like floor and wall sections, as well as the supporting structures that surround the containment buildings and reactor vessels. 

The Westinghouse AP1000 units the company is using are the first to be built in the U.S. 

Bechtel 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. 

Rising costs and the bankruptcy of Westinghouse delayed the project, but construction went back into full swing after Georgia Power, also a subsidiary of Southern Co., announced that cooling tower owners — Oglethorpe Power, MEAG Power and Dalton Utilities — had reached an agreement on how to handle about $2.3 billion in extra costs. The project's costs are estimated at $25 billion, according to The Wall Street Journal.

According to the U.S. Energy Information Administration, as of Oct. 31, 2020, there were 56 commercial nuclear power plants in operation in the U.S. The facilities are in 28 states and include 94 nuclear power reactors. Of the nuclear power plants currently in operation, 32 have two reactors and three have three reactors. The last nuclear reactor to come online was the Watts Bar Unit 2 in Spring City, Tennessee, which began commercial operation in October 2016.