A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nuclear fission is passed to a working fluid, which in turn runs through steam turbines. These either drive a ship's propellers or turn electrical generators' shafts. Nuclear generated steam in principle can be used for industrial process heat or for district heating. Some reactors are used to produce isotopes for medical and industrial use, or for production of weapons-grade plutonium. As of 2022, the International Atomic Energy Agency reports there are 422 nuclear power reactors and 223 nuclear research reactors in operation around the world.
United States naval reactors are nuclear reactors used by the United States Navy aboard certain ships to generate the steam used to produce power for propulsion, electric power, catapulting airplanes in aircraft carriers, and a few more minor uses. Such naval nuclear reactors have a complete power plant associated with them. All U.S. Navy submarines and supercarriers built since 1975 are nuclear-powered by such reactors. There are no commissioned conventional (non-nuclear) submarines or aircraft carriers left in the U.S. Navy, since the last conventional carrier, USS Kitty Hawk, was decommissioned in May 2009. The U.S. Navy had nine nuclear-powered cruisers with such reactors also, but they have since been decommissioned. Reactors are designed by a variety of contractors, then developed and tested at one of several government owned and prime contractor-operated facilities: Bettis Atomic Power Laboratory in West Mifflin, Pennsylvania and its associated Naval Reactors Facility in Idaho, and Knolls Atomic Power Laboratory in Niskayuna, New York and its associated Kesselring site in West Milton, New York, all under the management of the office of Naval Reactors. Sometimes there were full-scale nuclear-powered prototype plants built at the Naval Reactors Facility, Kesselring, and Windsor to test the nuclear plants, which were operated for years to train nuclear-qualified sailors.
The D1G reactor was a prototype naval reactor designed for the United States Navy to provide electricity generation and propulsion on warships. The D1G designation stands for:
The D2G reactor was a naval reactor used by the United States Navy from 1962 to provide propulsion and electricity generation on warships. Ships powered by the reactor were decommissioned at around the end of the 20th century. The D2G designation stands for:
USS Long Beach (CLGN-160/CGN-160/CGN-9) was a nuclear-powered guided missile cruiser in the United States Navy and the world's first nuclear-powered surface combatant. She was the third Navy ship named after the city of Long Beach, California.
The A3W reactor was a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships. Like all operational U.S. naval reactors it was a pressurized water reactor (PWR) design. The A3W designation stands for:
A nuclear-powered icebreaker is an icebreaker with an onboard nuclear power plant that produces power for the vessel's propulsion system. Although more expensive to operate, nuclear-powered icebreakers provide a number of advantages over their diesel-powered counterparts, especially along the Northern Sea Route where heavy power demand associated with icebreaking, limited refueling infrastructure along the Siberian coast, and endurance required make diesel-powered icebreaker operations challenging. As of 2023, Russia is the only country that builds and operates nuclear-powered icebreakers, having built a number of such vessels to aid shipping along the Northern Sea Route and Russian arctic outposts since the Soviet era.
The S6G reactor is a naval reactor used by the United States Navy to provide electricity generation and propulsion on Los Angeles-class attack submarines. The S6G designation stands for:
A nuclear submarine is a submarine powered by a nuclear reactor, but not necessarily nuclear-armed. Nuclear submarines have considerable performance advantages over "conventional" 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 range virtually unlimited, making the only limits on voyage times being imposed by such factors as the need to restock food or other consumables.
Nuclear marine propulsion is propulsion of a ship or submarine with heat provided by a nuclear reactor. The power plant heats water to produce steam for a turbine used to turn the ship's propeller through a gearbox or through an electric generator and motor. Nuclear propulsion is used primarily within naval warships such as nuclear submarines and supercarriers. A small number of experimental civil nuclear ships have been built.
A nuclear navy, or nuclear-powered navy, refers to the portion of a navy consisting of naval ships powered by nuclear marine propulsion. The concept was revolutionary for naval warfare when first proposed. Prior to nuclear power, submarines were powered by diesel engines and could only submerge through the use of batteries. In order for these submarines to run their diesel engines and charge their batteries they would have to surface or snorkel. The use of nuclear power allowed these submarines to become true submersibles and unlike their conventional counterparts, they became limited only by crew endurance and supplies.
Air-independent propulsion (AIP), or air-independent power, is any marine propulsion technology that allows a non-nuclear submarine to operate without access to atmospheric oxygen. AIP can augment or replace the diesel-electric propulsion system of non-nuclear vessels.
The A1B reactor is an aircraft carrier nuclear reactor developed by the United States Navy. It is used in Gerald R. Ford-class aircraft carriers to provide electrical and propulsion energy. The A1B is the first naval reactor produced by Bechtel Corporation, which has "performed engineering and/or construction services on more than 80 percent of [land-based] nuclear plants in the United States".
The California class was a pair of nuclear-powered guided-missile cruisers operated by the United States Navy between 1974 and 1998. Other than their nuclear power supply and lack of helicopter hangars, ships of the California class were comparable to other guided-missile cruisers of their era, such as the Belknap class. The class was built as a follow-up to the nuclear-powered Long Beach, Bainbridge, and Truxtun classes. Like all of the nuclear cruisers, which could steam for years between refuelings, the California class was designed in part to provide high endurance escort for the navy's nuclear aircraft carriers, which were often limited in range due to their conventionally powered escorts continuously needing to be refueled.
The CG(X) program, also known as the Next Generation Cruiser program, was a United States Navy research program to develop a replacement vessel for its 22 Ticonderoga-class cruisers. Original plans were for 18–19 ships, based on the 14,500 ton Zumwalt-class destroyer with additional ballistic missile defense and area air defense for a carrier group. These vessels were to enter service beginning in 2017. The program was ended in 2010 with its mission to be fulfilled by the successor to the Flight III Arleigh Burke-class destroyers.
The S5W reactor is a nuclear reactor used by the United States Navy to provide electricity generation and propulsion on warships. The S5W designation stands for:
Leahy-class cruisers were a class of guided-missile cruisers built for the United States Navy. They were originally designated as Destroyer Leaders (DLG), but in the 1975 cruiser realignment they were reclassified as guided-missile cruisers (CG).
The United States Navy Nuclear Propulsion community consists of Naval Officers and Enlisted members who are specially trained to run and maintain the nuclear reactors that power the submarines and aircraft carriers of the United States Navy. Operating more than 80 nuclear-powered ships, the United States Navy is currently the largest naval force in the world.
In the early 1960s, the United States Navy was the world's first to have nuclear-powered cruisers as part of its fleet. The first such ship was USS Long Beach (CGN-9). Commissioned in late summer 1961, she was the world's first nuclear-powered surface combatant. She was followed a year later by USS Bainbridge (DLGN-25). While Long Beach was a 'true cruiser', meaning she was designed and built as a cruiser, Bainbridge began life as a frigate, though at that time the Navy was using the hull code "DLGN" for "destroyer leader, guided missile, nuclear". This was prior to the enactment of the 1975 ship reclassification plan, in which frigates (DLG/DLGN), which were essentially large destroyers, were reclassified as cruisers, so that the US Navy's numbers would compete with those of the Soviet Navy. Long Beach, the largest of all the nuclear cruisers, was equipped with a C1W cruiser reactor, while all the others were equipped with D2G destroyer reactors.
