New Nuclear Unit in Georgia Reaches Key Milestone

A new nuclear unit at a site in Georgia has safely reached initial criticality, Georgia Power announced on March 6.

“Initial 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,” the investor-owned utility said.

Vogtle Unit 3 continues with startup testing, which demonstrates the integrated operation of the primary coolant system and steam supply system at design temperature and pressure with fuel inside the reactor.

Vogtle Unit 3 is adjacent to the operating Units 1 and 2, near Waynesboro, Georgia. Unit 3 and a second new unit are two 1,100-megawatt Westinghouse AP1000 nuclear reactors being constructed in Burke County, Ga.

A reactor achieves criticality when the nuclear fission reaction becomes self-sustaining. Achieving initial criticality is necessary to continue the startup of the unit in order to generate sufficient heat for the production of electricity.

Now that the Unit 3 reactor has reached criticality, operators will continue to raise power to support synchronizing the generator to the electric grid and begin producing electricity. Then, operators will continue increasing power through multiple steps, ultimately raising power to 100 percent. These tests are designed to ensure all systems are operating together and to validate operating procedures prior to declaration of commercial operation.

The in-service date for Unit 3 is projected during May or June 2023.

Southern Nuclear will operate the new units on behalf of the co-owners: Georgia Power, Oglethorpe Power, MEAG Power and Dalton Utilities.