The company said the project to build two new Generation III+ Westinghouse AP1000 nuclear power plants is about 94% complete for Unit 3 with the total Vogtle-3 and -4 project approximately 88% complete.
The completion of the cold hydro testing milestone prepares the site for the last major test remaining for Unit 3, hot functional testing, ahead of initial fuel load.
Cold hydro testing of Unit 3 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, the reactor coolant system was filled with water and pressurised above-normal operating conditions, then lowered to normal design pressure while comprehensive inspections were conducted to verify the systems meet design standards.
Georgia Power said it continues to expect to meet the November 2021 and November 2022 regulatory-approved in-service dates for Units 3 and 4, respectively.
Georgia Power also announced that the first reactor coolant pump had been started up on Unit 3. This initial run verifies the RCP operates as designed. During operations, the RCPs will circulate water through the reactor vessel and steam generators, providing forced flow of the reactor coolant through the reactor core, to the steam generator and then back again to support operations.
Additionally, the US Nuclear Regulatory Commission has issued the first operator licences to 62 reactor and senior reactor operators for Vogtle-3 and -4.
The two Vogtle units are the only commercial nuclear power reactors under construction in the US. Construction of Unit 3 began in March 2013 and of Unit 4 in November 2013.