The scheduled maintenance was the first since the Generation III+ VVER V-491 pressurised water reactor unit began commercial operation in October 2018.
Rosatom said work included assessments of various key components and the reactor core.
Pre-commissioning testing began recently at Leningrad 2-1’s sister unit, Leningrad 2-2, which is expected to be physically started up in March 2020.
The existing Leningrad nuclear station has three commercially operating RMBK-1000 units and a permanently shut-down RBMK unit, Leningrad-1. The Leningrad 2 station will have four VVER-1200 units.
Leningrad-2 and Leningrad-4 are in operation while Leningrad-3 has been undergoing scheduled repairs since 2 November.