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 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 Trafalgar class is a class of nuclear-powered fleet submarines (SSNs) in service with the Royal Navy, and the successor to the Swiftsure class. Like the majority of Royal Navy nuclear submarines, all seven boats were constructed at Barrow-in-Furness shipyard, Cumbria. With only one boat remaining active and in commission and six retired from the seven originally in service, the class makes up part of the Royal Navy's nuclear-powered ‘hunter-killer’ submarine force. The Trafalgar class has nearly been replaced by the larger and more capable Astute class, of which five are commissioned.
The Astute class is the latest class of nuclear-powered fleet submarines (SSNs) in service with the Royal Navy. The boats are being constructed by BAE Systems Submarines at Barrow-in-Furness. Seven boats will be constructed: the first of class, Astute, was launched by Queen Camilla, in 2007, commissioned in 2010, and declared fully operational in May 2014. The Astute class is the replacement for the Trafalgar-class fleet submarines in Royal Navy service.
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:
HMS Tireless was the third Trafalgar-class nuclear submarine of the Royal Navy. Tireless is the second submarine of the Royal Navy to bear this name. Launched in March 1984, Tireless was sponsored by Sue Squires, wife of Admiral 'Tubby' Squires, and commissioned in October 1985.
The seventh HMS Dreadnought was the United Kingdom's first nuclear-powered submarine, built by Vickers Armstrongs at Barrow-in-Furness. Launched by Queen Elizabeth II on Trafalgar Day 1960 and commissioned into service with the Royal Navy in April 1963, she continued in service until 1980. The submarine was powered by a S5W reactor, a design made available as a direct result of the 1958 US–UK Mutual Defence Agreement.
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.
Dounreay is a small settlement and the site of two large nuclear establishments on the north coast of Caithness in the Highland area of Scotland. It is on the A836 road nine miles west of Thurso.
The eleventh HMS Vanguard of the Royal Navy is the lead boat of her class of Trident ballistic missile-armed submarines. The submarine is based at Faslane, HMNB Clyde, Argyll, Scotland.
PLUTO was a materials testing nuclear reactor housed at the Atomic Energy Research Establishment, a former Royal Air Force airfield at Harwell, Oxfordshire in the United Kingdom.
The SLOWPOKE is a family of low-energy, tank-in-pool type nuclear research reactors designed by Atomic Energy of Canada Limited (AECL) beginning in the late 1960s. John W. Hilborn is the scientist most closely associated with their design. They are beryllium-reflected with a very low critical mass, but provide neutron fluxes higher than available from a small particle accelerator or other radioactive sources.
Experimental Breeder Reactor-II (EBR-II) was a sodium-cooled fast reactor designed, built and operated by Argonne National Laboratory at the National Reactor Testing Station in Idaho. It was shut down in 1994. Custody of the reactor was transferred to Idaho National Laboratory after its founding in 2005.
The Steam Generating Heavy Water Reactor (SGHWR) was a United Kingdom design for commercial nuclear reactors. It uses heavy water as the neutron moderator and normal "light" water as the coolant. The coolant boils in the reactor, like a boiling water reactor, and drives the power-extraction steam turbines.
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.
Rolls-Royce Submarines, a subsidiary of Rolls-Royce plc, operates three sites licensed to handle nuclear material, two of which are at Raynesway in Derby, and the other at Vulcan Nuclear Reactor Testing Establishment (NRTE), Dounreay, UK.
Scotland has a long history of nuclear research and electricity generation. Nuclear energy consistently accounts for 20-80% of the electric supply in Scotland depending on weather conditions for wind power generation and electricity demand. As of 2022, there is only one remaining operating nuclear power station in Scotland (Torness).
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 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).
