Testing began approximately two weeks after Unit 3 achieved criticality for the first time…
Hot functional testing is intended to prove that the nuclear plant is ready to begin loading fuel. According to the March 20, 2023 press release, it is a process that uses “the heat generated by the unit’s four reactor coolant pumps to raise the temperature and pressure of plant systems to normal operating levels.” And then, “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 allow the operators to test drive procedures and equipment functionality before loading nuclear fuel for the first time.
Georgia Power projected that Unit 4 will enter service in late fourth quarter 2023 or first quarter 2024, which would be roughly 8 to 12 months after hot functional testing began.
Southern Nuclear is projecting that Unit 3 will enter service in May or June of 2023. Unit 3 began hot functional testing in April of 2021, which will have been over 2 years before it entered service. The NRC identified issues with cable separation announced in August of 2021 that required remediation and resulted in delays, and vibrations in cooling system piping in January of 2023 resulted in additional delays. It is expected that these lessons learned have been incorporated into Unit 4’s development.