 The detailed engineering of the design was implemented at Larsen & <unk> 's submarine design center at their <unk> shipbuilding facility . Tata Power <unk> built the control systems for the submarine . The steam turbines and associated systems integrated with the reactor were supplied by <unk> Industries . The lead vessel underwent a long and extensive process of testing after its launch in July 2009 . The propulsion and power systems were tested with high @-@ pressure steam trials followed by harbor @-@ acceptance trials that included <unk> tests by flooding its ballast tanks and controlled dives to limited depths . INS Arihant 's reactor went critical for the first time on 10 August 2013 . On 13 December 2014 , the submarine set off for its extensive sea trials . 
