The containment vessel is a high-integrity steel structure that houses critical plant components. The top head is 40 metres in diameter, 12 metres tall, and weighs nearly 700,000 kg, more than two fully-loaded jumbo jets. It is comprised of 58 large plates, welded together, each more than an inch and a half thick.
The milestone comes about one year after the Unit 3 containment vessel top was lifted into place.
Before lifting the containment vessel top head, workers completed the placement of the 300-tonne polar crane inside the Unit 4 containment vessel. Once the unit is in operation, the polar crane will be used during refuelling outages to disassemble the reactor vessel and remove the reactor vessel’s integrated head package, which weighs approximately 215,000 kg and contains more than three miles of specialty electrical cables.
Georgia Power has not said when Vogtle-3 and Vogtle-4 will begin commercial operation, but said the project to build the two Generation III+ 1,117-MW Westinghouse AP1000 nuclear power reactors is now about 84% complete. Construction of Unit 3 began in March 2013 and of Unit 4 in November 2013.
Vogtle-3 and twin Vogtle-4 are the first commercial nuclear plants to be built in the US in a generation and the only new units under construction in the country.
Last month the Nuclear Regulatory Commission said it had received notice from Georgia Power’s parent company Southern Nuclear announcing plans to load nuclear fuel into Vogtle-3 starting on 23 November 2020. Earlier this month Georgia Power said it had ordered fuel for Vogtle-4.