Plant Vogtle Unit 4 reactor reaches initial criticality in start up testing, says Georgia Power

Erica Van Buren, Augusta Chronicle
·2 min read

Georgia Power announced on Wednesday that Unit 4 at Plant Vogtle has reached initial criticality, which means atoms are being split and nuclear heat is being made, leading to steam production.

Now that 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, experts say. Operators will then continue increasing power through multiple steps, ultimately raising power to 100%.

A reactor achieves criticality when the nuclear fission reaction becomes self-sustaining, according to a news release. Reaching initial criticality is necessary to continue the startup of Unit 4 in order to generate sufficient heat for the production of electricity.

Ongoing startup testing for Unit 4 will continue, which demonstrates the integrated operation of the primary coolant system and steam supply system at design temperature and pressure with fuel inside the reactor, according to a news release.

These tests are designed to ensure all systems are operating together and to validate operating procedures prior to declaration of commercial operation.

Plant Vogtle Unit 4: Georgia Power to start loading fuel into Plant Vogtle Unit 4, test the reactor

Vogtle Unit 3 entered commercial operation on July 31. The in-service date for Unit 4 is projected during the second quarter of 2024.

Nuclear energy currently provides about 25% of Georgia Power’s overall energy mix, including the existing units at Plant Vogtle and Georgia’s other nuclear facility at Plant Hatch in Baxley.

The expansion project to add Units 3 and 4 was first authorized in 2009 and has been hit with multiple delays and cost overruns since. The initial plan was to bring Unit 3 online in 2016 and Unit 4 the year after. Unit 3 began producing electricity in April. The project has cost more than double the projected $14 billion.

This reporting content is supported by a partnership with several funders and Journalism Funding Funding Partners.

Erica Van Buren is the climate change reporter for The Augusta Chronicle, part of the USA TODAY Network. Connect with her at EVanBuren@gannett.com or on X: @EricaVanBuren32.

This article originally appeared on Augusta Chronicle: Plant Vogtle Unit 4 reaches initial criticality in start up testing