Georgia Power on 26 April announced that hot functional testing had begun at unit 3 of its Vogtle NPP, while a cooling water tank was installed at unit 4. Georgia Public Service Commission (PSC) approved the Vogtle expansion project in 2009, including construction of two 1,117MWe Westinghouse AP1000 reactors which were expected to begin operation in 2016 and 2017.
The Vogtle project has faced numerous delays and financial challenges over the years with costs increasing from $14 billion to $25 billion. As well as the current COVID-19 pandemic, the 2017 bankruptcy of original contractor Westinghouse held back progress for several years. Vogtle is the only nuclear plant under construction in the USA and would be the first nuclear plant completed in more than three decades.
Hot functional testing of unit 3 was scheduled to begin in January and fuel loading in April, but Georgia Power said in January that a significant increase in Covid-19 cases and “other productivity challenges” may cause delays. However, the company said it still expected to achieve the November 2021 and 2022 regulatory-approved in-service dates for units 3 & 4.
Hot testing is the last series of major tests before initial fuel load. As part of the testing, the site team will begin running unit 3 plant systems without nuclear fuel and advance through the testing process towards reaching normal operating pressure and temperature.
Over the next several weeks, nuclear operators will use the heat generated by the unit’s four reactor coolant pumps to raise the temperature and pressure of plant systems to normal operating levels. Once normal operating temperature and pressure levels are achieved and sustained, the unit’s main turbine will be raised to normal operating speed using steam from the plant. During these series of tests, nuclear operators will be able to exercise and validate procedures as required ahead of fuel load. Hot functional testing is expected to take six to eight weeks.
At the same time, the passive containment cooling water storage tank, known (CB-20) has been lifted into place atop containment vessel and shield building roof of Vogtle unit 4. The placement also represents the last major crane lift at the project site.
This is a major part of the AP1000 reactor's advanced passive safety system. The tank, 35 feet tall and weighing more than 720,000 pounds, will hold approximately 750,000 gallons of water ready to flow down in the unlikely event of an emergency to help cool the reactor. The water can also be directed into the used fuel pool, while the tank itself can be refilled from water stored elsewhere on site.
The modules used for Vogtle 3 & 4 were made in advance of arriving to the project site and ready to be assembled into larger components that make up the nuclear units. Since 2011, major modules have been delivered to the site by rail and truck including floor and wall sections and supporting structures that surround the containment buildings and reactor vessels.