Chennai, Jan 22 (IANS): The Nuclear Power Corporation of India Ltd (NPCIL) is expected to feed power to the southern grid from its 1,000 MW unit at Kudankulam in Tamil Nadu in five days, according to a senior official.

The unit which was under annual maintenance shutdown for nearly seven months restarted fission on January 21.

The first unit will be connected to the southern grid in another five days after completing tests, R.S.Sundar, site director, Kudankulam Nuclear Power Project (KNPP), told IANS on Friday.

According to Power System Operation Corporation Ltd (POSOCO), the Kudankulam nuclear power plant is expected to be connected to the grid on January 24.

"A unit of this size (1,000 MW) after a long shut down takes some time to come back," a senior official at Atomic Energy Regulatory Board (AERB) told IANS on Friday.

He said nod is given to restart the fission process only after checking all the parameters of the reactor and other systems.

NPCIL is setting up two 1,000 MW atomic power plants at Kudankulam in Tirunelvelli district, around 650 km from here, at an outlay of around Rs.17,000 crore.

The first unit attained criticality, which is the beginning of the fission process, in July 2013.

Subsequently it was connected to the southern grid in October 2013.

However, commercial power generation began only December 31, 2014.

The unit also experienced breakdowns after commercial production started.

The unit was shut down in June 2015 for 60 days for refuelling and annual maintenance in June 2015 for 60 days for refuelling and maintenance.

Operating at full capacity, the unit supplies power to Tamil Nadu (562.5 MW), Puducherry (33.5 MW), Kerala (133 MW), Karnataka (221 MW) and Andhra Pradesh (50 MW).

The NPCIL skipped several deadlines in restarting the first unit and finally on January 21 the reactor restarted the fission process.

The second 1,000 MW unit at Kudankulam is expected to go critical, or start the fission process, for the first time sometime this year.

The fuel has to be loaded into the second reactor.

According to AERB official, the results of second unit's commissioning and inspection reports are being studied.

"After the reports are studied, AERB might lay down some conditions which have to be completed before NPCIL applies for the permission to load the fuel," he said.

India will be signing the remaining agreements with Russia for the third and fourth units at Kudankulam, estimated to cost around Rs.40,000 crore. The site work is expected to begin for these two units sometime this year.

Negotiations are on with Russia for fifth and sixth units.