Nuclear Submarine Technology and Missions
A nuclear submarine is, in the most basic terms, an undersea vessel that uses nuclear energy to power its engines. The significance of this and the reason the nuclear submarine revolutionized undersea warfare is that unlike nearly all other power sources, a nuclear reactor is not dependent on oxygen from the air. A submarine's crew needs oxygen to breathe, but the amount is far less than an oxygen using engine requires. Sufficient breathing oxygen can be carried for a long undersea voyage. Nuclear submarines therefore can remain submerged for weeks or even months at a time, nearly undetectable from above.
A nuclear submarine is the ultimate stealth weapon, to a far greater degree than any other weapon system, even a non nuclear submarine. The importance of a nuclear submarine's freedom to operate without an engine air supply is so important as to deserve further explanation. Other high powered engines steam, gasoline, and gas turbine (jet) all require very large amounts of oxygen in order to operate. The oxygen is used to burn fuel, providing heat that drives the engine.
Thus, none of these engines can operate underwater unless oxygen is provided from tanks, or drawn from a pipe or tube reaching to the surface. This places a severe limit on their use in submarines. It is true that seawater contains dissolved oxygen fish obtain this from their gills, which allows them to breathe. A submarine, however, is enormously larger than any fish. (Whales and other sea mammals must come to the surface to breathe.)
Even if artificial gills for a submarine's engines could be built, they would have to be of immense size to obtain enough oxygen, much larger than submarine itself. No such submarine would be practical. Water itself is largely oxygen, chemically bound to hydrogen (H2O). However, the energy needed to separate it from the hydrogen is greater than ...