Prime Minister Manmohan Singh described it as a "giant stride" in the progress of the country's indigenous capabilities. Defence Minister A.K. Antony also lauded the "tireless efforts" of the large team that had worked on the project.
The miniature nuclear reactor on INS Arihant (slayer of enemies) went critical early Saturday and the submarine was on its own power.
"The reactor in INS Arihant is functioning well. It will be shut down later to study the reports generated," Atomic Energy Commission (AEC) chairman R.K. Sinha told IANS over phone.
He said the design was unique as compared to a land-based reactor.
"The reactor was designed and manufactured in India," he added. The submarine reactor was developed from a land-based prototype located in Kalpakkam, around 70km from Chennai.
Speaking to IANS over phone, Bhabha Atomic Research Centre director Sekhar Basu said: "After a reactor goes critical (beginning of the nuclear fission process), it is shut down to check the reports. Then the reactor physics experiments will be done. Unlike land based power reactors, shutting down and restarting a submarine reactor is not a big problem."
The 82.5 MW nuclear reactor for submarine has been designed at Kalpakkam by PRP Centre - PRP originally stood for Plutonium Reprocessing Project - under the BARC. Prior to his current position, Basu was heading the PRP.
The reactor attained "criticality" after months of testing at the navy's submarine facility at Visakhapatnam, Andhra Pradesh, said sources.
They said the 6,000-tonne submarine will head to open sea for extensive sea trials that include firing of nuclear capable K-15 missiles. The sources said the sea trials were expected to take about 18 months.
Once operational, the submarine will provide India the third leg of its nuclear triad - the capacity to fire nuclear weapons from land, sea and air. The army has nuclear capable Agni and Prithvi-II missiles in its arsenal and the air force has aircraft capable of delivering nuclear warheads.
Sources said the nuclear submarine has advantages over conventional submarine as it can stay under water for months, making its detection very difficult.
They said India has a declared no-first use policy for nuclear weapons and having sea based capability to fire such weapons was critical for a credible deterrence.
"Once INS Arihant becomes operational, India's deterrent ability will increase manifold," an official said.
Manmohan Singh expressed happiness at the nuclear propulsion reactor on board INS Arihant achieving "criticality" and said he looked forward to early commissioning of the submarine.
Antony also congratulated defence scientists, personnel of Indian Navy and other organisations for activation of nuclear reactor and termed the step as a "very important milestone towards self-reliance in critical areas."
Defence analyst Gulshan Luthra, who had broken the news of India's first nuclear test and withdrawal of Canadian nuclear assistance as the first international reaction in May 1974, described the development as a sign of near-maturity.
"We need to be members of nuclear and missile technology denial regimes, go in for four to five more SSBN (nuclear powered, nuclear armed) class submarines and also at least two or three large (60,000 tonnes-plus) nuclear powered aircraft carriers. The good thing is the government is working in these directions," Luthra told IANS.
He said that INS Arihant should be able to conduct underwater missile tests by early 2015. The missiles, however, will not be nuclear-tipped during the tests.
Strategic analyst Uday Bhaskar said the significance of the reactor going critical "lies in the manner in which this technological accomplishment has been achieved by the Indian nuclear submarine establishment".
"The nuclear propulsion is a complex multidisciplinary process and a closely guarded techno-strategic capability that only five nations have acquired to date," Bhaskar, Distinguished Fellow at the Society for Policy Studies, told IANS.
"The reactor going critical is an important punctuation, but there are more stages to be successfully completed - such as the sea-trials; testing the missile et al," he said.
--IANS (Posted on 10-08-2013)