Unit 4 at Vogtle nuclear plant reaches initial criticality stage
Unit 4 at the Vogtle nuclear expansion project near Waynesboro, Ga., has safely reached initial criticality, Georgia Power announced this week.
Initial criticality, a key step during the startup testing sequence, demonstrates that operators have safely started the nuclear reaction inside the second reactor for the first time. In other words, atoms are being split and nuclear heat is being made, which will be used to produce steam.
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 enough heat for the production of electricity.
Going forward, Vogtle Unit 4 continues with startup testing. The goal is to demonstrate the integrated operation of the primary coolant system and steam supply system at design temperature and pressure with fuel inside the reactor. These tests are designed to ensure all systems are operating together and to validate operating procedures prior to commercial operation.
The in-service date for Unit 4 is projected during the second quarter of 2024.
Further, now that the Unit 4 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.
Vogtle Unit 3 entered commercial operation on July 31, 2023. It is now providing safe, reliable, emission-free energy to Georgia.
When in full operation, each of the new units can produce enough electricity to power an estimated 500,000 homes and businesses.
