Vogtle Nuclear Unit 3 remains projected to be placed into service during May or June 2023, according to the latest quarterly filings released by Southern Company.

On March 6, Unit 3 achieved initial criticality and on April 1, the generator successfully synchronized to the power grid and generated electricity for the first time.

According to the filings, the projected schedule for Unit 3 primarily depends on the progression of pre-operational testing and start-up, which may be impacted by further equipment, component or other operational challenges.

Operators are continuing to perform tests at different power levels and address various equipment and component issues as they are identified.

On March 15 with Unit 3 in Mode 1 at 18%, the reactor automatically tripped due to the loss of two reactor coolant pumps when their electrical buses failed to transfer after a main generator excitation protective relay tripped. The incident was reported to the Nuclear Regulatory Commission.

Operators responded and stabilized the plant by engaging relief valves that removed decay heat. Units 1, 2, and 4 were not affected.

The two AP-1000 reactors at Vogtle Units 3 and 4, each with a capacity of approximately 1,100 MW, are the first new nuclear units to be built in the U.S. in more than 30 years. Cost overruns and construction problems have long delayed the project.

Southern Nuclear will operate Vogtle Units 3 and 4 on behalf of co-owners Georgia Power, Oglethorpe Power, MEAG Power and Dalton Utilities.

Hot functional testing for Unit 4 began on March 20, and fuel load is projected for the third quarter of 2023. Unit 4 is projected to be placed in service during late fourth quarter 2023 or the first quarter 2024.

According to the quarterly filings, the timeline for Unit 4 depends on potential impacts from testing activities overlapping with Unit 3 start-up and commissioning, as well as overall construction productivity and production levels, particularly in subcontractor scopes of work; and maintaining appropriate labor levels.

This post appeared first on Power Engineering.