aircraft carriers can function for years prior to needing a refuel. A small quantity of nuclear fuel allows a submarine to operate beneath the surface at high speeds for an unlimited duration. The nuclear reactor onboard produces heat that drives a steam turbine, which in turn powers the submarine’s propeller that propels the craft forward. Before nuclear power was employed on the USS Nautilus in 1954, submarines utilized diesel-electric engines, which restricted their time submerged.
The electric motors, which activated when the submarine submerged, had to be recharged after traveling just 80 miles or, in optimal conditions, after four days of slow underwater movement. Recharging the batteries necessitated running the diesel engine, which required air, forcing the submarine to surface. Operating the diesel engine was essential for re-energizing the batteries in preparation for the next dive. In contrast, nuclear submarines can theoretically stay submerged for years without having to surface.