The country's first 540 mega watt pressurised heavy water reactor in Tarapur attained criticality on Sunday, Atomic Energy Commission Chairman Dr Anil Kakodkar said.

However, the new reactor -- unit 4 of the Tarapur atomic power station, which is the flagship plant of the Nuclear Power Corporation of India Limited, will be connected to the western grid for commercial purposes before August 2005, he said.

With this, the total nuclear power generated in the country would be 3310 MW, Kakodkar added.

He said the NPCIL currently produced 2,770 MW of electricity.

Before connecting to the grid, the plant would undergo various tests, as it is the first completely indigenously designed, large plant.