The unit four of indigenously-developed 220 MW capacity Atomic Power plant at Kaiga in Karnataka attained criticality on Sunday thereby making India the sixth country in the world to have 20 or more nuclear power plants in operation. The announcement of Kaiga-4 attaining criticality was made by Atomic Energy Commission Chairman Srikumar Banerjee in the presence of Nuclear Power Corporation of India Limited, NPCIL, Chairman-cum-Managing Director Shreyans Kumar Jain and a number of senior officials at the plant site.