The loading of enriched uranium fuel in the 1000 MW Russian-made reactor would be completed by this month end and power generation resume thereafter, KNPP Director R S Sundar said.
The first unit has been operational commercially since December 2014.
As regards the second unit, removal of dummy fuel rods was underway, he told reporters here on the sidelines of a two-day expo "Engergising Future India", organised jointly by the KKNP and the Anna university Tirunelveli region.
Sundar said the concrete laying for the fourth and fifth units of the KNPP would begin next year.