Nuclear submarines and aircraft carriers operate with nuclear reactors on board. The atoms in the nuclear reactor divide, releasing energy in the form of heat. This heat is used to create high-pressure steam. The steam turns the propulsion turbines that provide the power needed to turn the propeller.
Nuclear marine propulsion is the propulsion of a ship or submarine with heat provided by a nuclear reactor. The power plant heats the water to produce steam for a turbine that is used to turn the ship's propeller through a gearbox or through an electrical generator and engine. Nuclear propulsion is mainly used in naval warships, such as nuclear submarines and supercarriers. A small number of experimental civilian nuclear craft have been built.
Nuclear energy is particularly suitable for ships, which need to be at sea for long periods without refueling, or for powerful underwater propulsion. Today, more than 150 ships are powered by small nuclear reactors. The United States Navy operates about 100 nuclear ships. Although most nuclear-powered vessels are submarines, they range in type from icebreakers to aircraft carriers.
A nuclear submarine receives its electricity from a nuclear reactor. The environmental benefits of nuclear energy are indisputable, however, they are not widespread for several reasons. Among modern warships, they are second in size after large aircraft carriers, and are similar in size to the battleships of the Second World War era. This set of standards refers to a detailed and comprehensive Safety Code for nuclear merchant ships, which was approved by the IMO Assembly in 1981.In addition, nuclear waste can cause serious water pollution, destroying marine life and, as a consequence, also human life.
The dismantling of nuclear-powered submarines has become an important task for both the United States and Russia. Nuclear propulsion has proven to be technically and economically essential in the Russian Arctic, where operating conditions are beyond the capacity of conventional icebreakers. The high efficiency of nuclear energy also allows these submarines to operate at high speed for longer periods than conventional diesel-electric submarines. More specifically, if there is a reactor on a ship, the entire crew is automatically considered to be working in radiation and should not be exposed to more than 5 rems per year.
Nuclear technology has also helped increase navigation in the Arctic from two to ten months a year, and year-round in the Western Arctic. Nuclear-powered ships are much more expensive than those with conventional (petroleum-based) power sources, and especially in peacetime, it's not entirely clear which technology is cheaper in the long run. The following are ships that are or were in commercial or civil use and have nuclear marine propulsion. In the future, restrictions on the use of fossil fuels in transportation may cause marine nuclear propulsion to become more widespread use.
Some small modular reactors (SMR) are similar to marine propulsion reactors in terms of capacity and some design considerations, and therefore, nuclear marine propulsion (whether civil or military) is sometimes proposed as an additional niche market for SMRs. Russia built 248 nuclear submarines and five surface naval vessels powered by 468 reactors between 1950 and 2003.