Cold functional testing of unit 3 at the Vogtle nuclear power plant near Waynesboro, Georgia, has been completed, Georgia Power announced yesterday. The tests mark the first time the reactor systems have been operated together with the auxiliary systems.

Cold functional tests are carried out to confirm whether components and systems important to safety are properly installed and ready to operate in a cold condition. Their main purpose is to verify the leak-tightness of the primary circuit and components - such as the pressure vessels, pipelines and valves of both the nuclear and conventional islands - and to clean the main circulation pipes.

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 the completion of cold hydro testing prepares the site for the last major test remaining for unit 3 - hot functional testing - ahead of initial fuel loading. These tests aim to simulate the temperatures and pressures which the reactor's systems will be subjected to during normal operation.

"Every milestone achieved at the Vogtle 3 and 4 project represents another major step towards operations of the first new nuclear units in the US in more than 30 years," said Georgia Power Chairman, President and CEO Paul Bowers. "Completion of cold hydro testing not only helps pave the way for initial fuel load, it also moves us closer to bringing online a carbon-free asset that will provide clean energy for our customers, our state and the country for the next 60 to 80 years."

Georgia Power also announced the first reactor coolant pump (RCP) at unit 3 had successfully been started up, verifying the pump operates as designed. During operation, the RCPs 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.

In addition, the US Nuclear Regulatory Commission has issued the first operator licences to 62 Reactor and Senior Reactor Operators for Vogtle units 3 and 4.

Construction of Vogtle unit 3 began in March 2013 and unit 4 in November the same year. Southern Nuclear and Georgia Power, both subsidiaries of Southern Company, took over management of the construction project in 2017 following Westinghouse's Chapter 11 bankruptcy. Construction of unit 3 is now about 94% complete, Georgia Power said, with the total Vogtle 3 and 4 expansion project approximately 88% complete. The utility said it continues to expect to meet the November 2021 and November 2022 regulatory-approved in-service dates for units 3 and 4, respectively.