A nuclear submarine is a submarine powered by a nuclear reactor , but not necessarily nuclear-armed . Nuclear submarines have considerable performance advantages over "conventional" (typically diesel-electric ) submarines. Nuclear propulsion , being completely independent of air, frees the submarine from the need to surface frequently, as is necessary for conventional submarines. The large amount of power generated by a nuclear reactor allows nuclear submarines to operate at high speed for long periods, and
The limited energy stored in electric batteries means that even the most advanced conventional submarine can only remain submerged for a few days at slow speed, and only a few hours at top speed, though recent advances in air-independent propulsion have somewhat ameliorated this disadvantage. The high cost of nuclear technology means that relatively few of the world's military powers have fielded nuclear submarines. Radiation incidents have occurred within the Soviet submarines including serious nuclear and
The idea for a nuclear-powered submarine was first proposed in the United States Navy by the Naval Research Laboratory 's physicist Ross Gunn in 1939. [4] The Royal Navy began researching designs for nuclear propulsion plants in 1946. [5]