US Georgia Power says hot functional testing has begun at unit 4 of the Vogtle NPP, marking the last series of major tests before the initial fuel load. This will verify the successful operation of reactor components and systems and confirm that the reactor is ready for fuel to be loaded. The tests involve running unit 4 plant systems, without nuclear fuel in the reactor approaching normal operating pressure and temperature.

As part of the testing process, nuclear operators will use the heat generated by the unit's four reactor coolant pumps to raise the temperature and pressure of plant systems to normal operating levels. Once normal operating temperature and pressure levels are achieved and sustained, the unit's main turbine will be raised to normal operating speed using steam from the plant. This will enable operators to exercise and validate procedures as required ahead of fuel load.

Vogtle 4 is expected to enter service in late 2023 or early 2024. Vogtle 3 reached first criticality earlier in March and is expected to begin commercial operation in May or June. Both are 1,117 MWe Westinghouse AP1000 reactors.

Units 1&2 – both 1,215 MWe reactors supplied by Westinghouse – were completed in 1987 and 1989. In 2009, the Nuclear Regulatory Commission (NRC) renewed their licences for an additional 20 years. Georgia Public Service Commission approved the new reactors for the Vogtle expansion in early 2009 and construction activities began the same year. At that time Vogtle 3&4 were expected to cost about $14bn and to enter service in 2016 and 2017 but suffered a series of delays.

Southern Nuclear and Georgia Power, both subsidiaries of Southern Company, took over management of the project in 2017 following Westinghouse's Chapter 11 bankruptcy. A partnership of Cameco Corporation and Brookfield Renewable Partners is currently in the process of acquiring Westinghouse.

In February Georgia Power’s parent company Southern Company said the total cost of the project to build Vogtle 3&4 will cost its owners more than $30bn. Georgia Power owns 45.7% of the project; Oglethorpe Power Corp owns 30%; the Municipal Electric Authority of Georgia (MEAG) owns 22.7%; and the city of Dalton owns 1.6%.

Image: The Vogtle nuclear power plant (courtesy of Georgia Power)