Georgia Power announced the completion of cold hydro testing for Vogtle Unit 4 near Waynesboro, Georgia. The completion is required to support the last major test remaining for Unit 4, hot functional testing, which is expected to begin by the end of the first quarter of 2023.

Plant Vogtle Units 3 and 4, representing 2,200 MW, are the first nuclear units to be built in the U.S. in more than three decades. 

Cost overruns and construction problems have delayed the project. Project partners have disputed over rising construction costs and their stake in the venture. Nuclear fuel load recently begun at Vogtle Unit 3, which is currently expected to come online by the end of the first quarter of 2023. Unit 4 is expected at the end of 2023.

Cold hydro testing of Unit 4 confirmed the reactor’s coolant system functions as designed and verified the welds, joints, pipes and other components of the coolant system and associated high-pressure systems do not leak when under pressure.

As part of the testing, Georgia Power said the reactor coolant system was filled with water and pressurized above-normal operating conditions, then lowered to normal design pressure while comprehensive inspections were conducted to verify the systems meet design standards.

Prior to cold hydro testing, Unit 4 underwent closed vessel testing in November. This process verifies that the pipes and valves in the Unit 4 reactor coolant system are installed as designed and helps ensure safety systems function properly.

To carry out closed vessel testing on the plant’s passive safety systems, Georgia Power said workers installed the reactor vessel head as well as the lower and upper reactor internals and flow restrictors, which will be used during hot functional testing to mimic flow through the reactor core. 

Around the same time, the Unit 4 turbine was rotated on its turning gear for the first time, demonstrating the turbine was assembled with quality and that integrated oil systems function as designed.

The main turbine system consists of one high-pressure turbine and four low-pressure turbines. Rotating the turbines on the turning gear ties in all the oil systems and a significant number of supporting systems in the turbine island, which is a separate structure outside of the unit’s nuclear containment building.

Once operational, Georgia Power said the turbine will rotate at 1,800 revolutions per minute, propelled by steam produced by the unit’s two steam generators using heat transferred from the nuclear reactor. 

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