That day, the Shang-class Type 093 submersible, operating off the coast of Shanghai, reportedly got stuck while diving in the defensive systems constructed by its own army, namely “a chain and anchor barrier constructed by the Chinese Navy is used”. to capture American and Allied submarines,” the Secret Service report said.
Lack of oxygen
It then remained stuck at the bottom of the water for several hours with 55 crew members on board, including 22 officers, 7 cadets, 9 non-commissioned officers and 17 sailors. A duration that should not be his downfall, since a ship of this type is designed to stay below sea level almost indefinitely and the oxygen on board is produced by electrolysis: the seawater is filtered and broken down into oxygen and hydrogen. The latter is ventilated overboard or drained at depth. And carbon dioxide scrubbers remove the CO2 exhaled by the crew.
Same process as spacecraft, except nuclear submarines use an infinitely reusable system that periodically releases CO2 into the sea.
But on that day, the 107m-long submarine suffered a terrible failure: “The oxygen system on board suffered a catastrophic failure, resulting in the poisoning of the crew,” according to British intelligence. This is despite the rapid intervention of the Chinese military, which freed and reassembled the ship within six hours. It is possible that the batteries were discharged prematurely due to the crew’s escape maneuvers and this energy was then not available for oxygen production.