Nuclear submarine

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 long interval between refuelings grants a virtually unlimited range, making the only limits on voyage times factors such as the need to restock food or other consumables. Thus nuclear propulsion solves the problem of limited mission duration that all electric (battery or fuel cell powered) submarines face.

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 radiation accidents, but American naval reactors starting with the S1W and subsequent designs have operated without incident since the launch of USS Nautilus (SSN-571) in 1954.

In the US classification, nuclear-powered submarines are designated as SSxN, where the SS denotes submarine, x=G means that the submarine is equipped with guided missiles (usually cruise missiles), x=B means that the submarine is equipped with ballistic missiles (usually intercontinental) and the N means that the submarine is nuclear-powered. SSN refers to nuclear-powered attack submarines, which do not carry missiles.

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. The Royal Navy began researching designs for nuclear propulsion plants in 1946.

Construction of the world's first nuclear-powered submarine was made possible by the successful development of a nuclear propulsion plant by a group of scientists and engineers in the United States at the Naval Reactors Branch of the Bureau of Ships and the Atomic Energy Commission. In July 1951, the U.S. Congress authorized construction of the first nuclear-powered submarine, Nautilus, under the leadership of Captain Hyman G. Rickover, USN (sharing a name with Captain Nemo's fictional submarine Nautilus in Jules Verne's 1870 novel Twenty Thousand Leagues Under the Seas, the first demonstrably practical submarine Nautilus, and another USS Nautilus (SS-168) that served with distinction in World War II).^{[citation needed]}

The Westinghouse Corporation was assigned to build its reactor. After the submarine was completed at the Electric Boat Company, First Lady Mamie Eisenhower broke the traditional bottle of champagne on Nautilus' bow, and the submarine was commissioned USS Nautilus (SSN-571), on 30 September 1954. On 17 January 1955, she departed Groton, Connecticut, to begin sea trials. The submarine was 320 feet (98 m) long and cost about $55 million. Recognizing the utility of such vessels, the British Admiralty formed plans to build nuclear-powered submarines.

The Soviet Union soon followed the United States in developing nuclear-powered submarines in the 1950s. Stimulated by the U.S. development of Nautilus, Soviets began work on nuclear propulsion reactors in the early 1950s at the Institute of Physics and Power Engineering, in Obninsk, under Anatoliy P. Alexandrov, later to become head of the Kurchatov Institute. In 1956, the first Soviet propulsion reactor designed by his team began operational testing. Meanwhile, a design team under Vladimir N. Peregudov worked on the vessel that would house the reactor. After overcoming many obstacles, including steam generation problems, radiation leaks, and other difficulties, the first nuclear submarine based on these combined efforts, K-3 Leninskiy Komsomol of the Project 627 Kit class, called a November-class submarine by NATO, entered service in the Soviet Navy in 1958.