Stating that the country was on the threshold of a new milestone in its quest for civil nuclear energy, Prime Minister Manmohan Singh today announced that the first nuclear reactor with Russian collaboration at Kudankulam would start operating soon with the second reactor to follow later in the current year.

''As we pursue our national growth objectives to meet the rising aspirations of our people, the supply of affordable clean energy will be one of our foremost national challenges and a key priority for our government. Nuclear energy will remain an essential and increasingly important element of our energy mix. We are in the process of expanding our indigenous nuclear power programme,'' he said on the occasion of Department of Atomic Energy's Lifetime Achievement Awards for 2011 here.