India's first nuclear missile submarine, the $2.9 Billion INS Arihant (Sanskrit for "Slayer of Enemies"), set sail in 2016. It suffered catastrophic damage in early 2017 when "water rushed in as a hatch on the rear side was left open by mistake while it was at harbor". It was out of commission for almost a year because they had to replace all of the pipes, particularly the pressurized water coolant pipes for the nuclear reactor, after they came in contact with sea water.