The containment vessel serves as a barrier to protect the public and surrounding communities by containing material produced inside the reactor vessel in the unlikely event of an emergency.
The structural integrity test called for the vessel to be pressurised for the first time and then closely monitored. While pressurised, each accessible weld seam on the containment vessel was inspected by specially trained inspectors.
The integrated leak rate test examined individual component and integrated systems to verify that the containment vessel and its isolation valves, piping and electrical penetrations, and hatches properly performed their intended safety functions. The integrated leak rate test will be performed periodically during the lifetime of the plant.
The completion of this containment vessel milestone marks progress toward hot functional testing and critical testing on the primary and secondary sides of the unit, which are required ahead of initial fuel load.
Georgia Power and Southern Nuclear, the companies building the Vogtle-3 and -4 Generation III AP1000 nuclear plants, recently said schedules for pre-commissioning tests had been revised because of the impact of the Covid-19 pandemic.
Cold hydrostatic testing, originally scheduled for July 2020, will be pushed back to the autumn of 2020.
Georgia Power said it will continue to work towards fuel loading before the end of 2020, although this is officially scheduled for 2021.
The company said the overall schedule remains unchanged with in-service dates of November 2021 for Unit 3 and November 2022 for Unit 4.
In May Georgia Power said the project to build the two new plants was 85% complete and direct construction of Unit 3 was 90% complete.
The two plants are the only two commercial reactor units under construction in the US.