Hot functional testing marks the last series of major tests for the new Westinghouse AP1000 nuclear unit ahead of initial fuel load.
Georgia Power said the testing represents a significant step towards operations and providing customers with a reliable, carbon-free energy source for the next 60 to 80 years.
Hot functional testing is carried out to verify the successful operation of reactor components and systems together and confirm the reactor is ready for fuel load.
As part of the testing, the site team will begin running Unit 4 plant systems, without nuclear fuel in the reactor, and advance through the testing process towards reaching 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.
Earlier this month Vogtle-3, an identical 1,117-MW pressurised water reactor unit, achieved first criticality.
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 Vogtle-4 in November 2013. They are the first units of their kind being built in the US.
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.