State nuclear operator Nuclear Power Corporation of India Ltd said the 202-MW unit reached criticality on 19 May and is now in the process of being synchronised to the grid.
The unit was taken off line after a coolant leak caused the reactor to automatically shut down in March 2016. The identical Unit 2 was taken off line in 2015 following a coolant channel leak, and restarted in September 2018.
Kakrapar-1 and -2, both Indian-designed reactors, entered commercial operation in 1993 and 1995 respectively. There are also two 630-MW PHWRs under construction at the site. Kakrapar-3 is expected to be completed this year and Kakrapar-4 in 2020, NPCIL said.