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99-698: The ZEEP ( Zero Energy Experimental Pile ) reactor was a nuclear reactor built at the Chalk River Laboratories near Chalk River , Ontario , Canada (which superseded the Montreal Laboratory for nuclear research in Canada). ZEEP first went critical at 15:45 on September 5, 1945. ZEEP was the first operational nuclear reactor outside the United States. The reactor was designed by Canadian, British and French scientists as

198-479: A nuclear proliferation risk as they can be configured to produce plutonium , as well as tritium gas used in boosted fission weapons . Reactor spent fuel can be reprocessed to yield up to 25% more nuclear fuel, which can be used in reactors again. Reprocessing can also significantly reduce the volume of nuclear waste, and has been practiced in Europe, Russia, India and Japan. Due to concerns of proliferation risks,

297-558: A " neutron howitzer ") produced a barium residue, which they reasoned was created by fission of the uranium nuclei. In their second publication on nuclear fission in February 1939, Hahn and Strassmann predicted the existence and liberation of additional neutrons during the fission process, opening the possibility of a nuclear chain reaction . Subsequent studies in early 1939 (one of them by Szilárd and Fermi), revealed that several neutrons were indeed released during fission, making available

396-478: A 70 MWt reactor such as Hyperion's. In response to its members' interest in nuclear propulsion, Lloyd's Register has also re-written its 'rules' for nuclear ships, which concern the integration of a reactor certified by a land-based regulator with the rest of the ship. The overall rationale of the rule-making process assumes that in contrast to the current marine industry practice where the designer/builder typically demonstrates compliance with regulatory requirements, in

495-441: A crucial role in generating large amounts of electricity with low carbon emissions, contributing significantly to the global energy mix. Just as conventional thermal power stations generate electricity by harnessing the thermal energy released from burning fossil fuels , nuclear reactors convert the energy released by controlled nuclear fission into thermal energy for further conversion to mechanical or electrical forms. When

594-500: A few attempts at using liquid sodium-cooled reactors. A primary water circuit transfers heat generated from nuclear fission in the fuel to a steam generator ; this water is kept under pressure so it does not boil. This circuit operates at a temperature of around 250 to 300 °C (482 to 572 °F). Any radioactive contamination in the primary water is confined. Water is circulated by pumps; at lower power levels, reactors designed for submarines may rely on natural circulation of

693-561: A few experimental ships. The U.S.-built NS  Savannah , completed in 1962, was primarily a demonstration of civil nuclear power and was too small and expensive to operate economically as a merchant ship. The design was too much of a compromise, being neither an efficient freighter nor a viable passenger liner. The German-built Otto Hahn , completed in 1968, a cargo ship and research facility, sailed some 650,000 nautical miles (1,200,000 km) on 126 voyages over 10 years without any technical problems. It proved too expensive to operate and

792-445: A gas or a liquid metal (like liquid sodium or lead) or molten salt – is circulated past the reactor core to absorb the heat that it generates. The heat is carried away from the reactor and is then used to generate steam. Most reactor systems employ a cooling system that is physically separated from the water that will be boiled to produce pressurized steam for the turbines , like the pressurized water reactor . However, in some reactors

891-420: A land-based nuclear power plant, which increases the probability of fission to the level where a sustained reaction can occur. Some marine reactors run on relatively low-enriched uranium , which requires more frequent refueling. Others run on highly enriched uranium , varying from 20% U, to the over 96% U found in U.S. submarines , in which the resulting smaller core is quieter in operation (a big advantage to

990-444: A land-based reactor that always remains upright. Salt water corrosion is an additional problem that complicates maintenance. As the core of a seagoing reactor is much smaller than a power reactor, the probability of a neutron intersecting with a fissionable nucleus before it escapes into the shielding is much lower. As such, the fuel is typically more highly enriched (i.e., contains a higher concentration of U vs. U) than that used in

1089-442: A large fissile atomic nucleus such as uranium-235 , uranium-233 , or plutonium-239 absorbs a neutron, it may undergo nuclear fission. The heavy nucleus splits into two or more lighter nuclei, (the fission products ), releasing kinetic energy , gamma radiation , and free neutrons . A portion of these neutrons may be absorbed by other fissile atoms and trigger further fission events, which release more neutrons, and so on. This

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1188-424: A less effective moderator. In other reactors, the coolant acts as a poison by absorbing neutrons in the same way that the control rods do. In these reactors, power output can be increased by heating the coolant, which makes it a less dense poison. Nuclear reactors generally have automatic and manual systems to scram the reactor in an emergency shut down. These systems insert large amounts of poison (often boron in

1287-457: A marine reactor must be physically small, so it must generate higher power per unit of space. This means its components are subject to greater stresses than those of a land-based reactor. Its mechanical systems must operate flawlessly under the adverse conditions encountered at sea, including vibration and the pitching and rolling of a ship operating in rough seas. Reactor shutdown mechanisms cannot rely on gravity to drop control rods into place as in

1386-691: A modified version of their own, the PWR2 . The largest nuclear submarines ever built are the 26,500 tonne Russian Typhoon class . The smallest nuclear warships to date are the 2,700 tonne French Rubis -class attack submarines. The U.S. Navy operated an unarmed nuclear submarine, the NR-1 Deep Submergence Craft , between 1969 and 2008, which was not a combat vessel but was the smallest nuclear-powered submarine at 400 tons. The United States and France have built nuclear aircraft carriers . The sole French nuclear aircraft carrier example

1485-551: A new facility near Sayda Bay is to provide storage in a concrete-floored facility on land for some submarines in the far north. Russia built a floating nuclear power plant for its far eastern territories. The design has two 35 MWe units based on the KLT-40 reactor used in icebreakers (with refueling every four years). Some Russian naval vessels have been used to supply electricity for domestic and industrial use in remote far eastern and Siberian towns. In 2010, Lloyd's Register

1584-570: A number of ways: A kilogram of uranium-235 (U-235) converted via nuclear processes releases approximately three million times more energy than a kilogram of coal burned conventionally (7.2 × 10 joules per kilogram of uranium-235 versus 2.4 × 10 joules per kilogram of coal). The fission of one kilogram of uranium-235 releases about 19 billion kilocalories , so the energy released by 1 kg of uranium-235 corresponds to that released by burning 2.7 million kg of coal. A nuclear reactor coolant – usually water but sometimes

1683-536: A part of an effort to produce plutonium for nuclear weapons during World War II . It was developed while the Montreal Laboratory and Chalk River Laboratories research facility were under the supervision of the National Research Council of Canada (NRC). ZEEP was instrumental in the development of the NRX and NRU reactors, which led to the development of the successful CANDU reactor . ZEEP

1782-465: A patent on reactors on 19 December 1944. Its issuance was delayed for 10 years because of wartime secrecy. "World's first nuclear power plant" is the claim made by signs at the site of the EBR-I , which is now a museum near Arco, Idaho . Originally called "Chicago Pile-4", it was carried out under the direction of Walter Zinn for Argonne National Laboratory . This experimental LMFBR operated by

1881-773: A pile (hence the name) of graphite blocks, embedded in which was natural uranium oxide 'pseudospheres' or 'briquettes'. Soon after the Chicago Pile, the Metallurgical Laboratory developed a number of nuclear reactors for the Manhattan Project starting in 1943. The primary purpose for the largest reactors (located at the Hanford Site in Washington ), was the mass production of plutonium for nuclear weapons. Fermi and Szilard applied for

1980-407: A planned typical lifetime of 30–40 years, though many of those have received renovations and life extensions of 15–20 years. Some believe nuclear power plants can operate for as long as 80 years or longer with proper maintenance and management. While most components of a nuclear power plant, such as steam generators, are replaced when they reach the end of their useful lifetime, the overall lifetime of

2079-471: A reactor. One such process is delayed neutron emission by a number of neutron-rich fission isotopes. These delayed neutrons account for about 0.65% of the total neutrons produced in fission, with the remainder (termed " prompt neutrons ") released immediately upon fission. The fission products which produce delayed neutrons have half-lives for their decay by neutron emission that range from milliseconds to as long as several minutes, and so considerable time

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2178-529: A set of theoretical nuclear reactor designs. These are generally not expected to be available for commercial use before 2040–2050, although the World Nuclear Association suggested that some might enter commercial operation before 2030. Current reactors in operation around the world are generally considered second- or third-generation systems, with the first-generation systems having been retired some time ago. Research into these reactor types

2277-452: A shaft connects to the vessel's propellers. In another form of drive system, the turbine turns an electrical generator, and the electric power produced is fed to one or more drive motors for the vessel's propellers. The Russian , U.S. and British navies rely on direct steam turbine propulsion, while French and Chinese ships use the turbine to generate electricity for propulsion ( turbo-electric transmission ). Some nuclear submarines have

2376-602: A single reactor, but Russian submarines have two, and so had USS  Triton . Most American aircraft carriers are powered by two reactors, but USS  Enterprise had eight. The majority of marine reactors are of the pressurized water type, although the U.S. and Soviet navies have designed warships powered with liquid metal cooled reactors . Marine-type reactors differ from land-based commercial electric power reactors in several respects. While land-based reactors in nuclear power plants produce up to around 1600 megawatts of net electrical power (the nameplate capacity of

2475-468: A submarine). Using more-highly enriched fuel also increases the reactor's power density and extends the usable life of the nuclear fuel load, but is more expensive and a greater risk to nuclear proliferation than less-highly enriched fuel. A marine nuclear propulsion plant must be designed to be highly reliable and self-sufficient, requiring minimal maintenance and repairs, which might have to be undertaken many thousands of miles from its home port. One of

2574-664: A submerged circumnavigation of the Earth ( Operation Sandblast ), doing so in 1960. Nautilus , with a pressurized water reactor (PWR), led to the parallel development of other submarines like a unique liquid metal cooled (sodium) reactor in USS ; Seawolf , or two reactors in Triton , and then the Skate -class submarines, powered by single reactors, and a cruiser, USS  Long Beach , in 1961, powered by two reactors. By 1962,

2673-427: 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. Compared to oil- or coal-fuelled ships, nuclear propulsion offers the advantage of very long intervals of operation before refueling. All

2772-660: Is Charles de Gaulle , commissioned in 2001 (a successor is planned). The French carrier is equipped with catapults and arresters . The Charles de Gaulle has 42,000 tonnes, is the flagship of the French Navy (Marine Nationale). The ship carries a complement of Dassault Rafale M and E‑2C Hawkeye aircraft, EC725 Caracal and AS532 Cougar helicopters for combat search and rescue , as well as modern electronics and Aster missiles. The United States Navy operates 11 carriers, all nuclear-powered: The Kirov class, Soviet designation 'Project 1144 Orlan' ( sea eagle ),

2871-468: Is a class of nuclear-powered guided-missile cruisers of the Soviet Navy and Russian Navy , the largest and heaviest surface combatant warships (i.e. not an aircraft carrier or amphibious assault ship ) in operation in the world. Among modern warships, they are second in size only to large aircraft carriers , and of similar size to World War II era battleships . The Soviet classification of

2970-763: Is a nuclear-powered and nuclear-armed unmanned underwater vehicle under development by Rubin Design Bureau , capable of delivering both conventional and nuclear payloads . According to Russian state TV, it is able to deliver a thermonuclear cobalt bomb of up to 200 megatonnes (four times as powerful as the most powerful device ever detonated, the Tsar Bomba , and twice its maximum theoretical yield) against an enemy's naval ports and coastal cities. The following are ships that are or were in commercial or civilian use and have nuclear marine propulsion. Nuclear-powered civil merchant ships have not developed beyond

3069-473: Is considered. This is a small fast-neutron reactor using lead–bismuth eutectic cooling and able to operate for ten full-power years before refueling, and in service last for a 25-year operational life of the vessel. They conclude that the concept is feasible, but further maturity of nuclear technology and the development and harmonisation of the regulatory framework would be necessary before the concept would be viable. Nuclear propulsion has been proposed again on

ZEEP - Misplaced Pages Continue

3168-413: Is inserted deeper into the reactor, it absorbs more neutrons than the material it displaces – often the moderator. This action results in fewer neutrons available to cause fission and reduces the reactor's power output. Conversely, extracting the control rod will result in an increase in the rate of fission events and an increase in power. The physics of radioactive decay also affects neutron populations in

3267-428: Is known as a nuclear chain reaction . To control such a nuclear chain reaction, control rods containing neutron poisons and neutron moderators are able to change the portion of neutrons that will go on to cause more fission. Nuclear reactors generally have automatic and manual systems to shut the fission reaction down if monitoring or instrumentation detects unsafe conditions. The reactor core generates heat in

3366-405: Is mined, processed, enriched, used, possibly reprocessed and disposed of is known as the nuclear fuel cycle . Under 1% of the uranium found in nature is the easily fissionable U-235 isotope and as a result most reactor designs require enriched fuel. Enrichment involves increasing the percentage of U-235 and is usually done by means of gaseous diffusion or gas centrifuge . The enriched result

3465-401: Is produced. Fission also produces iodine-135 , which in turn decays (with a half-life of 6.57 hours) to new xenon-135. When the reactor is shut down, iodine-135 continues to decay to xenon-135, making restarting the reactor more difficult for a day or two, as the xenon-135 decays into cesium-135, which is not nearly as poisonous as xenon-135, with a half-life of 9.2 hours. This temporary state is

3564-496: Is provided with an internal neutron shield, which reduces the damage to the steel from constant neutron bombardment. Decommissioning nuclear-powered submarines has become a major task for U.S. and Russian navies. After defuelling, U.S. practice is to cut the reactor section from the vessel for disposal in shallow land burial as low-level waste (see the ship-submarine recycling program ). In Russia, whole vessels, or sealed reactor sections, typically remain stored afloat, although

3663-448: Is reaching or crossing their design lifetimes of 30 or 40 years. In 2014, Greenpeace warned that the lifetime extension of ageing nuclear power plants amounts to entering a new era of risk. It estimated the current European nuclear liability coverage in average to be too low by a factor of between 100 and 1,000 to cover the likely costs, while at the same time, the likelihood of a serious accident happening in Europe continues to increase as

3762-467: Is reported to be powered by a thorium-based molten salt reactor , making it a first thorium-powered container ship and, if completed, the largest nuclear-powered container ship in the world. Nuclear propulsion has proven both technically and economically feasible for nuclear-powered icebreakers in the Soviet , and later Russian , Arctic . Nuclear-fuelled ships operate for years without refueling, and

3861-416: Is required to determine exactly when a reactor reaches the critical point. Keeping the reactor in the zone of chain reactivity where delayed neutrons are necessary to achieve a critical mass state allows mechanical devices or human operators to control a chain reaction in "real time"; otherwise the time between achievement of criticality and nuclear meltdown as a result of an exponential power surge from

3960-467: Is still interest in nuclear propulsion. In November 2010 British Maritime Technology and Lloyd's Register embarked upon a two-year study with U.S.-based Hyperion Power Generation (now Gen4 Energy ), and the Greek ship operator Enterprises Shipping and Trading SA to investigate the practical maritime applications for small modular reactors. The research intended to produce a concept tanker-ship design, based on

4059-430: Is then converted into uranium dioxide powder, which is pressed and fired into pellet form. These pellets are stacked into tubes which are then sealed and called fuel rods . Many of these fuel rods are used in each nuclear reactor. Nuclear marine propulsion 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

ZEEP - Misplaced Pages Continue

4158-566: The EPR ), a typical marine propulsion reactor produces no more than a few hundred megawatts. Some small modular reactors (SMR) are similar to marine propulsion reactors in capacity and some design considerations and thus nuclear marine propulsion (whether civilian or military) is sometimes proposed as an additional market niche for SMRs. Unlike for land-based applications where hundreds of hectares can be occupied by installations like Bruce Nuclear Generating Station , at sea tight space limits dictate that

4257-490: The Manhattan Project . Eventually, the first artificial nuclear reactor, Chicago Pile-1 , was constructed at the University of Chicago , by a team led by Italian physicist Enrico Fermi, in late 1942. By this time, the program had been pressured for a year by U.S. entry into the war. The Chicago Pile achieved criticality on 2 December 1942 at 3:25 PM. The reactor support structure was made of wood, which supported

4356-517: The PWR , BWR and PHWR designs above, and some are more radical departures. The former include the advanced boiling water reactor (ABWR), two of which are now operating with others under construction, and the planned passively safe Economic Simplified Boiling Water Reactor (ESBWR) and AP1000 units (see Nuclear Power 2010 Program ). Rolls-Royce aims to sell nuclear reactors for the production of synfuel for aircraft. Generation IV reactors are

4455-524: The U.S. Atomic Energy Commission produced 0.8 kW in a test on 20 December 1951 and 100 kW (electrical) the following day, having a design output of 200 kW (electrical). Besides the military uses of nuclear reactors, there were political reasons to pursue civilian use of atomic energy. U.S. President Dwight Eisenhower made his famous Atoms for Peace speech to the UN General Assembly on 8 December 1953. This diplomacy led to

4554-777: The United States Navy had 26 operational nuclear submarines and another 30 under construction. Nuclear power had revolutionized the Navy. The United States shared its technology with the United Kingdom , while French , Soviet , Indian and Chinese development proceeded separately. After the Skate -class vessels, U.S. submarines were powered by a series of standardized, single-reactor designs built by Westinghouse and General Electric . Rolls-Royce plc built similar units for Royal Navy submarines, eventually developing

4653-477: The coolant also acts as a neutron moderator . A moderator increases the power of the reactor by causing the fast neutrons that are released from fission to lose energy and become thermal neutrons. Thermal neutrons are more likely than fast neutrons to cause fission. If the coolant is a moderator, then temperature changes can affect the density of the coolant/moderator and therefore change power output. A higher temperature coolant would be less dense, and therefore

4752-402: The "iodine pit." If the reactor has sufficient extra reactivity capacity, it can be restarted. As the extra xenon-135 is transmuted to xenon-136, which is much less a neutron poison, within a few hours the reactor experiences a "xenon burnoff (power) transient". Control rods must be further inserted to replace the neutron absorption of the lost xenon-135. Failure to properly follow such a procedure

4851-580: The 1986 Chernobyl disaster and 2011 Fukushima disaster . As of 2022 , the International Atomic Energy Agency reported there are 422 nuclear power reactors and 223 nuclear research reactors in operation around the world. The US Department of Energy classes reactors into generations, with the majority of the global fleet being Generation II reactors constructed from the 1960s to 1990s, and Generation IV reactors currently in development. Reactors can also be grouped by

4950-666: The Liability of Operators of Nuclear Ships , developed in 1962, would have made signatory national governments liable for accidents caused by nuclear vessels under their flag but was never ratified owing to disagreement on the inclusion of warships under the convention. Nuclear reactors under United States jurisdiction are insured by the provisions of the Price–Anderson Act . By 1990, there were more nuclear reactors powering ships (mostly military) than there were generating electric power in commercial power plants worldwide. Under

5049-736: The U.S. military sought other uses for nuclear reactor technology. Research by the Army led to the power stations for Camp Century, Greenland and McMurdo Station, Antarctica Army Nuclear Power Program . The Air Force Nuclear Bomber project resulted in the Molten-Salt Reactor Experiment . The U.S. Navy succeeded when they steamed the USS Nautilus (SSN-571) on nuclear power 17 January 1955. The first commercial nuclear power station, Calder Hall in Sellafield , England

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5148-472: The United States does not engage in or encourage reprocessing. Reactors are also used in nuclear propulsion of vehicles. Nuclear marine propulsion of ships and submarines is largely restricted to naval use. Reactors have also been tested for nuclear aircraft propulsion and spacecraft propulsion . Reactor safety is maintained through various systems that control the rate of fission. The insertion of control rods, which absorb neutrons, can rapidly decrease

5247-565: The World War II Allied Manhattan Project . The world's first artificial nuclear reactor, Chicago Pile-1, achieved criticality on 2 December 1942. Early reactor designs sought to produce weapons-grade plutonium for fission bombs , later incorporating grid electricity production in addition. In 1957, Shippingport Atomic Power Station became the first reactor dedicated to peaceful use; in Russia, in 1954,

5346-613: The ability to use unenriched uranium gave ZEEP and its descendants a number of distinct advantages. ZEEP continued to be used for basic research until 1970. It was decommissioned in 1973 and dismantled in 1997. In 1966 ZEEP was designated a historic site by Ontario, and commemorated with a historic plaque. Both this plaque and ZEEP itself are now on display at the Canada Science and Technology Museum in Ottawa , Canada. Nuclear reactor Nuclear reactors have their origins in

5445-569: The area was contaminated, like Fukushima, Three Mile Island, Sellafield, and Chernobyl. The British branch of the French concern EDF Energy , for example, extended the operating lives of its Advanced Gas-cooled Reactors (AGR) with only between 3 and 10 years. All seven AGR plants were expected to be shut down in 2022 and in decommissioning by 2028. Hinkley Point B was extended from 40 to 46 years, and closed. The same happened with Hunterston B , also after 46 years. An increasing number of reactors

5544-795: The beginning of his quest to produce the Einstein-Szilárd letter to alert the U.S. government. Shortly after, Nazi Germany invaded Poland in 1939, starting World War II in Europe. The U.S. was not yet officially at war, but in October, when the Einstein-Szilárd letter was delivered to him, Roosevelt commented that the purpose of doing the research was to make sure "the Nazis don't blow us up." The U.S. nuclear project followed, although with some delay as there remained skepticism (some of it from Enrico Fermi ) and also little action from

5643-458: The choices of coolant and moderator. Almost 90% of global nuclear energy comes from pressurized water reactors and boiling water reactors , which use water as a coolant and moderator. Other designs include heavy water reactors , gas-cooled reactors , and fast breeder reactors , variously optimizing efficiency, safety, and fuel type , enrichment , and burnup . Small modular reactors are also an area of current development. These reactors play

5742-467: The complexities of handling actinides , but significant scientific and technical obstacles remain. Despite research having started in the 1950s, no commercial fusion reactor is expected before 2050. The ITER project is currently leading the effort to harness fusion power. Thermal reactors generally depend on refined and enriched uranium . Some nuclear reactors can operate with a mixture of plutonium and uranium (see MOX ). The process by which uranium ore

5841-407: The cycle. Any water lost in the process can be made up by desalinated sea water added to the steam generator feed water. In the turbine, the steam expands and reduces its pressure as it imparts energy to the rotating blades of the turbine. There may be many stages of rotating blades and fixed guide vanes. The output shaft of the turbine may be connected to a gearbox to reduce rotation speed, then

5940-838: The direction of U.S. Navy Captain (later Admiral) Hyman G. Rickover , the design, development and production of nuclear marine propulsion plants started in the United States in the 1940s. The first prototype naval reactor was constructed and tested at the Naval Reactor Facility at the National Reactor Testing Station in Idaho (now called the Idaho National Laboratory ) in 1953. The first nuclear submarine , USS  Nautilus  (SSN-571) , put to sea in 1955 (SS

6039-688: The dissemination of reactor technology to U.S. institutions and worldwide. The first nuclear power plant built for civil purposes was the AM-1 Obninsk Nuclear Power Plant , launched on 27 June 1954 in the Soviet Union . It produced around 5 MW (electrical). It was built after the F-1 (nuclear reactor) which was the first reactor to go critical in Europe, and was also built by the Soviet Union. After World War II,

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6138-494: The energy of the neutrons that sustain the fission chain reaction : In principle, fusion power could be produced by nuclear fusion of elements such as the deuterium isotope of hydrogen . While an ongoing rich research topic since at least the 1940s, no self-sustaining fusion reactor for any purpose has ever been built. Used by thermal reactors: In 2003, the French Commissariat à l'Énergie Atomique (CEA)

6237-524: The first small nuclear power reactor APS-1 OBNINSK reached criticality. Other countries followed suit. Heat from nuclear fission is passed to a working fluid coolant (water or gas), which in turn runs through turbines . In commercial reactors, turbines drive electrical generator shafts. The heat can also be used for district heating , and industrial applications including desalination and hydrogen production . Some reactors are used to produce isotopes for medical and industrial use. Reactors pose

6336-407: The fission process generates heat, some of which can be converted into usable energy. A common method of harnessing this thermal energy is to use it to boil water to produce pressurized steam which will then drive a steam turbine that turns an alternator and generates electricity. Modern nuclear power plants are typically designed for a lifetime of 60 years, while older reactors were built with

6435-529: The form of boric acid ) into the reactor to shut the fission reaction down if unsafe conditions are detected or anticipated. Most types of reactors are sensitive to a process variously known as xenon poisoning, or the iodine pit . The common fission product Xenon-135 produced in the fission process acts as a neutron poison that absorbs neutrons and therefore tends to shut the reactor down. Xenon-135 accumulation can be controlled by keeping power levels high enough to destroy it by neutron absorption as fast as it

6534-465: The four-ship Virginia class . USS  Virginia  (CGN-38) was commissioned in 1976, followed by USS  Texas  (CGN-39) in 1977, USS  Mississippi  (CGN-40) in 1978 and finally USS  Arkansas  (CGN-41) in 1980. Ultimately, all these ships proved to be too costly to maintain and they were all retired between 1993 and 1999. SSV-33 Ural ( ССВ-33 Урал ; NATO reporting name : Kapusta [ Russian for " cabbage "])

6633-405: The fuel is contained within the nuclear reactor, so no cargo or supplies space is taken up by fuel, nor is space taken up by exhaust stacks or combustion air intakes. The low fuel cost is offset by high operating costs and investment in infrastructure, however, so nearly all nuclear-powered vessels are military. Most naval nuclear reactors are of the pressurized water type, with the exception of

6732-424: The fuel rods. This allows the reactor to be constructed with an excess of fissionable material, which is nevertheless made relatively safe early in the reactor's fuel burn cycle by the presence of the neutron-absorbing material which is later replaced by normally produced long-lived neutron poisons (far longer-lived than xenon-135) which gradually accumulate over the fuel load's operating life. The energy released in

6831-436: The future the nuclear regulators will wish to ensure that it is the operator of the nuclear plant that demonstrates safety in operation, in addition to the safety through design and construction. Nuclear ships are currently the responsibility of their own countries, but none are involved in international trade. As a result of this work in 2014 two papers on commercial nuclear marine propulsion were published by Lloyd's Register and

6930-447: The idea of nuclear fission as a neutron source, since that process was not yet discovered. Szilárd's ideas for nuclear reactors using neutron-mediated nuclear chain reactions in light elements proved unworkable. Inspiration for a new type of reactor using uranium came from the discovery by Otto Hahn , Lise Meitner , and Fritz Strassmann in 1938 that bombardment of uranium with neutrons (provided by an alpha-on-beryllium fusion reaction,

7029-449: The normal nuclear chain reaction, would be too short to allow for intervention. This last stage, where delayed neutrons are no longer required to maintain criticality, is known as the prompt critical point. There is a scale for describing criticality in numerical form, in which bare criticality is known as zero dollars and the prompt critical point is one dollar , and other points in the process interpolated in cents. In some reactors,

7128-581: The opportunity for the nuclear chain reaction that Szilárd had envisioned six years previously. On 2 August 1939, Albert Einstein signed a letter to President Franklin D. Roosevelt (written by Szilárd) suggesting that the discovery of uranium's fission could lead to the development of "extremely powerful bombs of a new type", giving impetus to the study of reactors and fission. Szilárd and Einstein knew each other well and had worked together years previously, but Einstein had never thought about this possibility for nuclear energy until Szilard reported it to him, at

7227-453: The other members of this consortium. These publications review past and recent work in the area of marine nuclear propulsion and describe a preliminary concept design study for a 155,000  DWT Suezmax tanker that is based on a conventional hull form with alternative arrangements for accommodating a 70 MWt nuclear propulsion plant delivering up to 23.5 MW shaft power at maximum continuous rating (average: 9.75 MW). The Gen4Energy power module

7326-406: The physics of radioactive decay and are simply accounted for during the reactor's operation, while others are mechanisms engineered into the reactor design for a distinct purpose. The fastest method for adjusting levels of fission-inducing neutrons in a reactor is via movement of the control rods . Control rods are made of so-called neutron poisons and therefore absorb neutrons. When a control rod

7425-463: The power plant is limited by the life of components that cannot be replaced when aged by wear and neutron embrittlement , such as the reactor pressure vessel. At the end of their planned life span, plants may get an extension of the operating license for some 20 years and in the US even a "subsequent license renewal" (SLR) for an additional 20 years. Even when a license is extended, it does not guarantee

7524-572: The reactor fleet grows older. The neutron was discovered in 1932 by British physicist James Chadwick . The concept of a nuclear chain reaction brought about by nuclear reactions mediated by neutrons was first realized shortly thereafter, by Hungarian scientist Leó Szilárd , in 1933. He filed a patent for his idea of a simple reactor the following year while working at the Admiralty in London, England. However, Szilárd's idea did not incorporate

7623-416: The reactor will continue to operate, particularly in the face of safety concerns or incident. Many reactors are closed long before their license or design life expired and are decommissioned . The costs for replacements or improvements required for continued safe operation may be so high that they are not cost-effective. Or they may be shut down due to technical failure. Other ones have been shut down because

7722-437: The reactor's output, while other systems automatically shut down the reactor in the event of unsafe conditions. The buildup of neutron-absorbing fission products like xenon-135 can influence reactor behavior, requiring careful management to prevent issues such as the iodine pit , which can complicate reactor restarts. There have been two reactor accidents classed as an International Nuclear Event Scale Level 7 "major accident":

7821-426: The relatively high enrichment of the uranium and by incorporating a " burnable poison " in the fuel elements, which is slowly depleted as the fuel elements age and become less reactive. The gradual dissipation of the "nuclear poison" increases the reactivity of the core to compensate for the lessening reactivity of the aging fuel elements, thereby extending the usable life of the fuel. The compact reactor pressure vessel

7920-411: The ship-type is "heavy nuclear-powered guided missile cruiser" ( Russian : тяжёлый атомный ракетный крейсер ). The ships are often referred to as battlecruisers by Western defence commentators due to their size and general appearance. The United States Navy at one time had nuclear-powered cruisers as part of its fleet. The first such ship was USS Long Beach (CGN-9) . Commissioned in 1961, she

8019-647: The small number of officials in the government who were initially charged with moving the project forward. The following year, the U.S. Government received the Frisch–Peierls memorandum from the UK, which stated that the amount of uranium needed for a chain reaction was far lower than had previously been thought. The memorandum was a product of the MAUD Committee , which was working on the UK atomic bomb project, known as Tube Alloys , later to be subsumed within

8118-400: The submarine, finally making it a true "underwater" vessel, rather than a "submersible" craft, which could only stay underwater for limited periods. It gave the submarine the ability to operate submerged at high speeds, comparable to those of surface vessels, for unlimited periods, dependent only on the endurance of its crew. To demonstrate this USS  Triton was the first vessel to execute

8217-442: The technical difficulties in designing fuel elements for a seagoing nuclear reactor is the creation of fuel elements that will withstand a large amount of radiation damage. Fuel elements may crack over time and gas bubbles may form. The fuel used in marine reactors is a metal- zirconium alloy rather than the ceramic UO 2 ( uranium dioxide ) often used in land-based reactors. Marine reactors are designed for long core life, enabled by

8316-445: The vessels have powerful engines, well-suited to the task of icebreaking. The Soviet icebreaker Lenin was the world's first nuclear-powered surface vessel in 1959 and remained in service for 30 years (new reactors were fitted in 1970). It led to a series of larger icebreakers, the 23,500 ton Arktika class of six vessels, launched beginning in 1975. These vessels have two reactors and are used in deep Arctic waters. NS Arktika

8415-424: The water for the steam turbines is boiled directly by the reactor core ; for example the boiling water reactor . The rate of fission reactions within a reactor core can be adjusted by controlling the quantity of neutrons that are able to induce further fission events. Nuclear reactors typically employ several methods of neutron control to adjust the reactor's power output. Some of these methods arise naturally from

8514-406: The water to reduce noise generated by the pumps. The hot water from the reactor heats a separate water circuit in the steam generator. That water is converted to steam and passes through steam driers on its way to the steam turbine . Spent steam at low pressure runs through a condenser cooled by seawater and returns to liquid form. The water is pumped back to the steam generator and continues

8613-678: The wave of decarbonization of marine shipping, which accounts for 3–4% of global greenhouse gas emissions. In December 5, 2023, the Jiangnan Shipyard under the China State Shipbuilding Corporation officially released a design of a 24000  TEU -class container ship — known as the KUN-24AP — at Marintec China 2023, a premier maritime industry exhibition held in Shanghai . The container ship

8712-687: Was a command and control naval ship operated by the Soviet Navy . SSV-33 ' s hull was derived from that of the nuclear-powered Kirov -class battlecruisers with nuclear marine propulsion. SSV-33 served in electronic intelligence , missile tracking, space tracking, and communications relay roles. Due to high operating costs, SSV-33 was laid up. SSV-33 carried only light defensive weapons. These were two AK-176 76 mm guns, four AK-630 30 mm guns, and four quadruple Igla missile mounts. The Poseidon ( Russian : Посейдон , " Poseidon ", NATO reporting name Kanyon ), previously known by Russian codename Status-6 ( Russian : Статус-6 ),

8811-481: Was a key step in the Chernobyl disaster . Reactors used in nuclear marine propulsion (especially nuclear submarines ) often cannot be run at continuous power around the clock in the same way that land-based power reactors are normally run, and in addition often need to have a very long core life without refueling . For this reason many designs use highly enriched uranium but incorporate burnable neutron poison in

8910-459: Was a traditional hull classification symbol for U.S. submarines, while SSN denoted the first "nuclear" submarine). The Soviet Union also developed nuclear submarines. The first types developed were the Project 627, NATO-designated November class with two water-cooled reactors, the first of which, K-3 Leninsky Komsomol , was underway under nuclear power in 1958. Nuclear power revolutionized

9009-427: Was commissioned in 1988. As of 2021 , it is the only nuclear-powered merchant ship in service. Civilian nuclear ships suffer from the costs of specialized infrastructure. The Savannah was expensive to operate since it was the only vessel using its specialized nuclear shore staff and servicing facility. A larger fleet could share fixed costs among more operating vessels, reducing operating costs. Despite this, there

9108-486: Was converted to diesel. The Japanese Mutsu , completed in 1972, was dogged by technical and political problems. Its reactor had significant radiation leakage and fishermen protested against the vessel's operation. All of these three ships used low-enriched uranium. Sevmorput , a Soviet and later Russian LASH carrier with icebreaking capability, has operated successfully on the Northern Sea Route since it

9207-494: Was investigating the possibility of civilian nuclear marine propulsion and rewriting draft rules (see text under Merchant Ships ). Insurance of nuclear vessels is not like the insurance of conventional ships. The consequences of an accident could span national boundaries, and the magnitude of possible damage is beyond the capacity of private insurers. A special international agreement, the Brussels Convention on

9306-788: Was officially started by the Generation ;IV International Forum (GIF) based on eight technology goals. The primary goals being to improve nuclear safety, improve proliferation resistance, minimize waste and natural resource utilization, and to decrease the cost to build and run such plants. Generation V reactors are designs which are theoretically possible, but which are not being actively considered or researched at present. Though some generation V reactors could potentially be built with current or near term technology, they trigger little interest for reasons of economics, practicality, or safety. Controlled nuclear fusion could in principle be used in fusion power plants to produce power without

9405-463: Was opened in 1956 with an initial capacity of 50 MW (later 200 MW). The first portable nuclear reactor "Alco PM-2A" was used to generate electrical power (2 MW) for Camp Century from 1960 to 1963. All commercial power reactors are based on nuclear fission . They generally use uranium and its product plutonium as nuclear fuel , though a thorium fuel cycle is also possible. Fission reactors can be divided roughly into two classes, depending on

9504-570: Was the first surface vessel to reach the North Pole . For use in shallow waters such as estuaries and rivers, shallow-draft, Taymyr -class icebreakers were built in Finland and then fitted with their single-reactor nuclear propulsion system in Russia . They were built to conform to international safety standards for nuclear vessels. All nuclear-powered icebreakers have been commissioned by

9603-649: Was the first to refer to "Gen II" types in Nucleonics Week . The first mention of "Gen III" was in 2000, in conjunction with the launch of the Generation IV International Forum (GIF) plans. "Gen IV" was named in 2000, by the United States Department of Energy (DOE), for developing new plant types. More than a dozen advanced reactor designs are in various stages of development. Some are evolutionary from

9702-468: Was the world's first nuclear-powered surface combatant . She was followed a year later by USS Bainbridge (DLGN-25) . While Long Beach 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 ". The last nuclear-powered cruisers the Americans would produce would be

9801-525: Was used to test reactivity effects and other physics parameters needed for reactor development at Chalk River Laboratories, including fuel lattices for the NRU reactor situated next door. ZEEP was one of the world's first heavy water reactors , and it was also designed to use natural (unenriched) uranium ; a feature carried through to the CANDU design. Uranium enrichment is a complex and expensive process; thus,

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