Rosenergoatom received parent Rosatom's approval of its project to upgrade Kalinin 1 in December 2009.
Improvements were made to the unit during scheduled maintenance outages from 2009 to 2014, Rosenergoatom said. During its 2014 outage, completed on 29 April, the turbine generator condenser, reactor control and protection system equipment, automated process control system, and transport airlock were all replaced. Other work included repairs to the unit's used fuel pool, as well as checks on the residual lifetime of other equipment, pipes, valves and building structures.
The licence was granted on 27 June and is valid until 28 June, 2025.
Rosenergoatom is now working on a life extension project for Kalinin 2, the service life of which expires in December 2016, Rosenergoatom - said on 30 June. The work required to achieve that life extension will be defined in the second half of this year, it said.
Kalinin nuclear power plant consists of four units. Units 1 and 2 are V-338 model VVER-1000s which began commercial operation in 1985 and 1987, respectively. Kalinin 3 and Kalinin 4 are both 950 MWe V-320 model VVER-1000 reactors, which were completed in 2004 and 2012. The plant is situated in the western Tver region near the town of Udomlya.