The S8G reactor is a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships. The S8G designation stands for:
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The S8G reactor was designed by General Electric for use on the Ohio-class submarines. The 220 MWth S8G reactor compartment for the Ohio submarines is 42 feet (13 m) in diameter, 55 feet (17 m) long and weighs 2,750 tons. [1]
This nuclear reactor utilizes natural circulation [2] [3] [4] which is capable of operating at a significant fraction of full power without reactor coolant pumps.
A land-based prototype of the reactor plant was built at Knolls Atomic Power Laboratory's Kesselring Site in West Milton, New York. The prototype was used for testing and crew training throughout the 1980s. In 1994, the core was replaced with an S6W reactor, designed for the then-new Seawolf-class submarine.
The prototype is equipped with an automatic reactor fill system that can flood the reactor with borated water in the event of a loss-of-coolant accident.
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:
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.
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:
USS Narwhal (SSN-671), a unique submarine, was the third vessel of the United States Navy to be named for the narwhal, a gray and white arctic whale with a unicorn-like, ivory tusk.
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:
The Rolls-Royce pressurised water reactor (PWR) series has powered the Royal Navy's nuclear submarines since the Valiant class, commissioned in 1966.
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.
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.
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 S9G reactor is a naval reactor used by the United States Navy to provide electricity generation and propulsion on Virginia-class submarines. The S9G designation stands for:
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 features a fast neutron spectrum and molten lead or lead-bismuth eutectic coolant. Molten lead or lead-bismuth eutectic can be used as the primary coolant because especially lead, and to a lesser degree bismuth have low neutron absorption and relatively low melting points. Neutrons are slowed less by interaction with these heavy nuclei and therefore, help make this type of reactor a fast-neutron reactor. In simple terms, if a neutron hits a particle with a similar mass, it tends to lose kinetic energy. In contrast, if it hits a much heavier atom such as lead, the neutron will "bounce off" without losing this energy. The coolant does, however, serve as a neutron reflector, returning some escaping neutrons to the core. Fuel designs being explored for this reactor scheme include fertile uranium as a metal, metal oxide or metal nitride. Smaller capacity lead-cooled fast reactors can be cooled by natural convection, while larger designs use forced circulation in normal power operation, but will employ natural circulation emergency cooling. No operator interference is required, nor pumping of any kind to cool the residual heat of the reactor after shutdown. The reactor outlet coolant temperature is typically in the range of 500 to 600 °C, possibly ranging over 800 °C with advanced materials for later designs. Temperatures higher than 800 °C are theoretically high enough to support thermochemical production of hydrogen through the sulfur-iodine cycle, although this has not been demonstrated.
The S6W reactor is a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships. The S6W designation stands for:
In the United States Navy, Refueling and Overhaul (ROH) refers to a lengthy refitting process or procedure performed on nuclear-powered naval ships, which involves replacement of expended nuclear fuel with new fuel and a general maintenance fix-up, renovation, and often modernization of the entire ship. In theory, such a process could simply involve only refueling or only an overhaul, but in practice, nuclear refueling is always combined with an overhaul. An ROH usually takes one to two years for submarines and up to almost three years for an aircraft carrier, performed at a naval shipyard. Time periods between ROHs on a ship have varied historically from about 5–20 years (for submarines) to up to 25 years (for Nimitz-class aircraft carriers). For modern submarines and aircraft carriers, ROHs are typically carried out about midway through their operating lifespan. There are also shorter maintenance fix-ups called availabilities for ships periodically at shipyards. A particularly lengthy refueling, maintenance, and modernization process for a nuclear aircraft carrier can last up to almost three years and be referred to as a Refueling and Complex Overhaul (RCOH).
The Columbia-class is an upcoming class of nuclear-powered ballistic missile submarines designed to replace the Ohio-class of the United States Navy. Construction of the first submarine began on 1 October 2020. It is scheduled to enter service in 2031.
...relying on...natural circulation reactor....