Monday, 29 September 2014


We've met the cute-looking nerpa Pusa sibirica before when we had an excursion into the vastness of Lake Baikal.  Nerpas are the only living species of seal that is exclusively fresh-water in its habitat and are rudely successful there, gobbling up copepods by the ton in one of the most productive aquatic biomass factories on the planet. They do this with the help of teeth that can puncture straight through a human thumb, as my pal Russ the Fish showed me yesterday.  Seals: not cute to copepods, penguins etc. It seemed appropriate for the Russian Navy Военно-морской Флот Российской Федерации to name a nuclear hunter-killer submarine after such a creature and the keel was laid down for K-152 Nerpa in 1993. It was the tail end of a production line that had been building subs against armageddon all through the years of the Cold War.  But with the fall of communism, there was less need for such toys and K-152 almost didn't get built. Construction was put on hold until 2004, when the Indian Naval Service stumped up the money to complete the project.

I've written recently about the effectiveness for inert gases like sulphur hexafluoride and halons as fire-suppressants.  Halons are related to the CFCs which are depleting the ozone above our heads, but instead of being ChloroFluoroCarbons, they tend to be BromoFluoroCarbons in which the ozone-potent Chlorines are replaced by less destructive Bromines.  Halons are also chemically stable even under extremes of temperature and denser than air so they are really useful for displacing oxygen from around flaming objects and so stopping combustion.

Shortly after launching and before K-152 was turned over to the Indians, the ship was sent out into the Sea of Japan for sea-trials with more than 200 people aboard.  About 1/3 were military personnel and the rest were dock-yard mateys, technicians and bureaucrats monitoring progress as the trials continued.  Early on 8th November 2008 the fire-safety system was accidentally turned on without warning and two forward compartments of the vessel had their water-tight doors closed automatically and the area flooded with vaporized R-114B2 aka 1,2-dibromo-tetrafluoro-ethane or Halon 2402.  20 people died because they couldn't get on their oxygen-support-systems over their heads in time and nobody can breathe halon for more than a couple of minutes and live.  It is the kind of incident that brings home the fact that burning charcoal in a barbecue and the combustion of glucose in a cell are both exothermic reactions requiring oxygen. At least as many people were injured in the accident: many of them from frost-bite to the lungs - R-114B2 cools down (it's the latent heat of evaporation, stupid) as it vaporizes. The death rate among civilians was much higher 17/127 (13%) than among the naval personnel 3/81 (3%).  But it was ever thus in maritime disasters as we saw with the sinking of the Empress of Ireland. Naval and Merchant Marine discipline can be draconian but at least it trains the crew to do the right thing when it matters. The lung-freezing gave me a little frisson myself because something similar happened to my own grand-father when he was left up in an observation balloon over the North Sea in winter.

Nothing daunted by the deaths, Nerpa was renamed INS Chakra and commissioned into the Indian Naval Service in due course.

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