Russian authorities are being quite open about the accident that killed 20 people on the nuclear attack submarine Nerpa on Saturday. Only days after starting sea trials, the boat was carrying a large number of civilian workers - there were 127 civilians on board, plus 81 sailors. According to Russian sources, the submarine's fire-suppression system discharged accidentally, asphyxiating the victims who had either no time to don respirators or no access to the gear.
The Akula-class boat had started construction before the collapse of the Soviet Union, with work being suspended in 1991, and according to several reports it had been completed, with updated combat systems, using funds from India, and was to be leased starting in 2009 to the Indian Navy.
The accident would not have directly damaged the ship, if it occurred as described, and it's too early to tell if, or by how much, those plans will be delayed. However, it is likely to further stress Indian relationships with Russia's navy and shipbuliders, already soured by delays in converting the Russian carrier Gorshkov into a full-deck carrier for the Indian Navy.