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Vogtle / Unit 3 Achieves First Criticality, Marking Key Nuclear Commissioning Milestone

By David Dalton
7 March 2023

Westinghouse-supplied AP1000 reactor scheduled to go commercial in May or June
Unit 3 Achieves First Criticality, Marking Key Nuclear Commissioning Milestone
The Vogtle-3 nuclear power plant is scheduled for commercial operation in May or June. Courtesy Georgia Power.
The Vogtle-3 nuclear power station in the US state of Georgia has achieved first criticality, a major landmark towards reaching commercial operation at the first new nuclear reactor built from scratch in decades in the US.

First criticality is a key step during the startup testing sequence and demonstrates that – for the first time – operators have safely started the nuclear reaction inside the reactor. This means atoms are being split and nuclear heat is being made, which will be used to produce steam.

Chris Womack, chairman, president and chief executive officer of Georgia Power, said the company remains focused on safely bringing the 1,117-MW pressurised water reactor (PWR) unit online, fully addressing any issues and getting it right at every level.

“Reaching initial criticality is one of the final steps in the startup process and has required tremendous diligence and attention to detail from our teams,” he said.

Georgia Power is the lead owner of the Vogtle project, for which Westinghouse has provided two Generation III+ AP1000 units. Construction of Vogtle-3 began in March 2013 and of identical unit Vogtle-4 in November 2013. They are the first units of their kind being built in the US.

Fuel loading at Vogtle-3 took place in October 2022 when Georgia Power said the unit was expected to enter service in the first quarter of 2023.

Project Has Seen Delays And Cost Overruns

The in-service date for Vogtle-3 when the project was approved in 2012 was 2016, but the project has seen a number of delays and cost overruns.

Most recently Georgia Power delayed the projected startup for Vogtle-3 to May or June, pushing back from the most recent deadline of the end of April. The company said Unit 4 will begin commercial operation sometime between this November and March 2024.

The causes of the latest set of delays at Unit 3 included a pipe part of a critical backup cooling system that was vibrating during startup testing. Construction workers had failed to install supports called for on blueprints. Georgia Power has also said it had to repair a slowly dripping valve and diagnose a problem involving water flow through reactor coolant pumps.

Georgia Power also said its share of the costs will rise by an additional $200m (€187m).

Southern Co, Georgia Power’s Atlanta-based parent, said the total cost of the project will cost all its owners more than $30bn, up from the original estimate of $14 bn.

Georgia Power owns 45.7% of the project, while Oglethorpe Power Corp owns 30%, the Municipal Electric Authority of Georgia owns 22.7% and the city of Dalton owns 1.6%.

Westinghouse Hails ‘Incredible Moment’

Georgia Power said Unit 3 would continue startup testing to show that its cooling system and steam supply system will work at the intense heat and pressure that a nuclear reactor creates. After that, operators will connect the plant to the electrical grid and gradually raise it to full power.

In a statement on Monday (6 March) Westinghouse hailed the milestone. “We are honored to share this incredible moment with Southern Nuclear, Georgia Power, and the project’s co-owners, and with the entire team at Vogtle,” Patrick Fragman, Westinghouse president and chief executive officer said.

The reactor manufacturer – which supplied the world’s first commercial PWR in 1957 – noted four AP1000 units currently operating in China “are currently setting operational performance records.” Four additional AP1000 reactors are under construction in China, and two more are planned.

“Poland recently selected the AP1000 reactor for its nuclear energy programme, nine units have been announced for Ukraine, and the technology is under consideration at multiple other sites in Central and Eastern Europe, the United Kingdom, and in the United States,” Westinghouse said.

The turbine building at the Vogtle-3 AP1000 nuclear power plant in the US state of Georgia. Courtesy Georgia Power.

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