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The S1G reactor is a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships. The S1G designation stands for:
This nuclear reactor was constructed by General Electric as a prototype for the USS Seawolf (SSN-575) submarine. It was a liquid metal cooled reactor using pure sodium to cool the core instead of water, because the higher temperature of liquid sodium (compared to pressurized water) enabled the production of more superheated steam in the steam generators. This resulted in a more efficient thermal cycle, yielding more shaft horsepower for a given reactor size. The reactor design had problems because of limited operating temperature constraints. The major disadvantage of this concept was the ignition of sodium when exposed to air. The reactor core was beryllium-moderated. [1] [2]
S1G was used for testing and training. Eventually a sodium leak resulted in a fire, and the facility was shut down. In the meantime, the S1W and S2W pressurized water reactors, conceived for the USS Nautilus (SSN-571), had demonstrated their superior reliability. The S1G reactor facility and its Horton sphere were later reused for the D1G prototype destroyer reactor.
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.
The S7G reactor was a prototype naval reactor designed for the United States Navy to provide electricity generation and propulsion on warships. The S7G designation stands for:
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 commissioned U.S. Navy submarines and supercarriers built since 1975 are nuclear powered, with the last conventional carrier, USS Kitty Hawk, being decommissioned in May 2009. The U.S. Navy also had nine nuclear-powered cruisers with such reactors, but they have since been decommissioned as well.
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:
A pressurized water reactor (PWR) is a type of light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants. In a PWR, the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy released by the fission of atoms. The heated, high pressure water then flows to a steam generator, where it transfers its thermal energy to lower pressure water of a secondary system where steam is generated. The steam then drives turbines, which spin an electric generator. In contrast to a boiling water reactor (BWR), pressure in the primary coolant loop prevents the water from boiling within the reactor. All light-water reactors use ordinary water as both coolant and neutron moderator. Most use anywhere from two to four vertically mounted steam generators; VVER reactors use horizontal steam generators.
USS Seawolf (SSN-575) was the third ship of the United States Navy to be named for the seawolf, the second nuclear submarine, and the only US submarine built with a liquid metal cooled (sodium), beryllium-moderated nuclear reactor, the S2G. Her overall design was a variant of Nautilus, but with numerous detail changes, such as a conning tower, stepped sail, and the BQR-4 passive sonar mounted in the top portion of the bow instead of further below. This sonar arrangement resulted in an unusual bow shape above the water for a U.S. submarine. Originally laid down in 1953, her distinctive reactor was later replaced with a standard pressurized water reactor, the replacement process lasting from 12 December 1958 to 30 September 1960.
The S5G reactor was a prototype naval reactor designed for the United States Navy to provide electricity generation and propulsion on submarines. The S5G 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.
The S1W reactor was the first prototype naval reactor used by the United States Navy to prove that the technology could be used for electricity generation and propulsion on submarines.
A fast-neutron reactor (FNR) or fast-spectrum reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons, as opposed to slow thermal neutrons used in thermal-neutron reactors. Such a fast reactor needs no neutron moderator, but requires fuel that is relatively rich in fissile material when compared to that required for a thermal-neutron reactor. Around 20 land based fast reactors have been built, accumulating over 400 reactor years of operation globally. The largest of this was the Superphénix Sodium cooled fast reactor in France that was designed to deliver 1,242 MWe. Fast reactors have been intensely studied since the 1950s, as they provide certain advantages over the existing fleet of water cooled and water moderated reactors. These are:
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.
The light-water reactor (LWR) is a type of thermal-neutron reactor that uses normal water, as opposed to heavy water, as both its coolant and neutron moderator; furthermore a solid form of fissile elements is used as fuel. Thermal-neutron reactors are the most common type of nuclear reactor, and light-water reactors are the most common type of thermal-neutron reactor.
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:
The lead-cooled fast reactor is a nuclear reactor design that use molten lead or lead-bismuth eutectic coolant. These materials can be used as the primary coolant because they have low neutron absorption and relatively low melting points. Neutrons are slowed less by interaction with these heavy nuclei so these reactors operate with fast neutrons.
A sodium-cooled fast reactor is a fast neutron reactor cooled by liquid sodium.
A steam generator is a heat exchanger used to convert water into steam from heat produced in a nuclear reactor core. They are used in pressurized water reactor between the primary and secondary coolant loops.
A liquid metal cooled nuclear reactor, or LMR is a type of nuclear reactor where the primary coolant is a liquid metal. Liquid metal cooled reactors were first adapted for breeder reactor power generation. They have also been used to power nuclear submarines.
The S2G reactor was a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships, and the only liquid metal cooled reactor yet deployed by the US Navy. The S2G designation stands for:
The S2W reactor was a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships. The S2W designation stands for:
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.