Escape from a disabled submarine: Decompression sickness risk estimation

Individual crewmember escape from a disabled U.S. Navy nuclear submarine ha s never been necessary, but remains an important contingency. Decompression sickness (DCS) is one of the foreseeable risks and a robust mathematical m odel of DCS incidence has been used to estimate the magnitude of this risk under a variety of escape scenarios. The model was calibrated with over 300 0 well-controlled human pressure exposures, less than 2% of which simulated pressure profiles of submarine escape. For disabled submarine depths <300 ft of sea water (fsw) and internal submarine pressures of <11 fsw (arguably the most likely conditions), the DCS risks are comparable to those routine ly undertaken by U.S. Navy divers-less than 5%. For progressively deeper de pths and especially for higher submarine internal pressures, the risk of DC S becomes much greater, including unknown chances of permanent injury and d eath. Variations from the baseline escape procedure are explored, including equipment differences, delays in exiting the submarine and changes in the oxygen content of the breathing mix.