New Delhi, May 19 (IANS): The loading of reactor fuel into the second unit of the Kudankulam Nuclear Power Plant (KNPP) in Tamil Nadu has been successfully completed, a source at the KNPP said on Thursday.

"The work of fuel loading into the second Unit of KNPP has been successfully completed today (Thursday). All 163 fuel assemblies have been loaded into the core," a source at the project told IANS over telephone.

"It took only four days to complete the process," he said.

The start-up stage, or the first fuels assembly of unit 2, began last week.

"A series of inspections and tests will be conducted under the Atomic Energy Regulatory Board (AERB) and International Atomic Energy Agency (IAEA) supervision before the work will start to achieve criticality," the source added.

Criticality for a nuclear reactor denotes the start of the fission process.

The 1,000 MW second unit is expected to go critical by the mid-2016.

Russia's state-run nuclear power corporation Rosatom are the builders of the KNPP, being operated by the Nuclear Power Corporation of India (NPCIL). The first 1,000 MW unit at Kudankulam has already been commissioned.

"KNPP started commercial operations in December 2014 and the first unit generates 1,000 MW of power. This is the first nuclear plant in the world where the post-Fukushima safety enhancement requirements are being implemented successfully," the source said.

The Kudankulam Nuclear Power Plant is equipped with state-of-the-art safety mechanisms with unique features that make them foolproof.