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110-521: The division also fulfils other security-related roles including testing the security of strategic sites, for example nuclear power plants and military facilities such as the submarine base of the Île Longue , Bretagne. Organization Within the Action Division there are three separate groups, The service's headquarters are located at the fort of Noisy-le-Sec . It replaced the Service Action of

220-451: A steam drum , and the furnace with its steam generating tubes and superheater coils. Necessary safety valves are located at suitable points to protect against excessive boiler pressure. The air and flue gas path equipment include: forced draft (FD) fan , air preheater (AP), boiler furnace, induced draft (ID) fan, fly ash collectors ( electrostatic precipitator or baghouse ), and the flue-gas stack . The boiler feed water used in

330-435: A vacuum of about −95 kPa (−28 inHg) relative to atmospheric pressure. The large decrease in volume that occurs when water vapor condenses to liquid creates the vacuum that generally increases the efficiency of the turbines. The limiting factor is the temperature of the cooling water and that, in turn, is limited by the prevailing average climatic conditions at the power station's location (it may be possible to lower

440-460: A condenser. The condenser is a heat exchanger which is connected to a secondary side such as a river or a cooling tower . The water is then pumped back into the steam generator and the cycle begins again. The water-steam cycle corresponds to the Rankine cycle . The nuclear reactor is the heart of the station. In its central part, the reactor's core produces heat due to nuclear fission. With this heat,

550-442: A coolant is heated as it is pumped through the reactor and thereby removes the energy from the reactor. The heat from nuclear fission is used to raise steam, which runs through turbines , which in turn power the electrical generators. Nuclear reactors usually rely on uranium to fuel the chain reaction. Uranium is a very heavy metal that is abundant on Earth and is found in sea water as well as most rocks. Naturally occurring uranium

660-402: A facility has been completely decommissioned it is released from regulatory control, and the licensee of the station no longer has responsibility for its nuclear safety. Generally speaking, nuclear stations were originally designed for a life of about 30 years. Newer stations are designed for a 40 to 60-year operating life. The Centurion Reactor is a future class of nuclear reactor that

770-660: A gas turbine, in the form of hot exhaust gas, can be used to raise steam by passing this gas through a heat recovery steam generator (HRSG). The steam is then used to drive a steam turbine in a combined cycle plant that improves overall efficiency. Power stations burning coal, fuel oil , or natural gas are often called fossil fuel power stations . Some biomass -fueled thermal power stations have appeared also. Non-nuclear thermal power stations, particularly fossil-fueled plants, which do not use cogeneration are sometimes referred to as conventional power stations . Commercial electric utility power stations are usually constructed on

880-442: A gas turbine. The steam generating boiler has to produce steam at the high purity, pressure and temperature required for the steam turbine that drives the electrical generator. Geothermal plants do not need boilers because they use naturally occurring steam sources. Heat exchangers may be used where the geothermal steam is very corrosive or contains excessive suspended solids. A fossil fuel steam generator includes an economizer ,

990-410: A generator on a common shaft. There is usually a high-pressure turbine at one end, followed by an intermediate-pressure turbine, and finally one, two, or three low-pressure turbines, and the shaft that connects to the generator. As steam moves through the system and loses pressure and thermal energy, it expands in volume, requiring increasing diameter and longer blades at each succeeding stage to extract

1100-480: A large scale and designed for continuous operation. Virtually all electric power stations use three-phase electrical generators to produce alternating current (AC) electric power at a frequency of 50 Hz or 60 Hz . Large companies or institutions may have their own power stations to supply heating or electricity to their facilities, especially if steam is created anyway for other purposes. Steam-driven power stations have been used to drive most ships in most of

1210-404: A nuclear reactor heats the reactor coolant. The coolant may be water or gas, or even liquid metal, depending on the type of reactor. The reactor coolant then goes to a steam generator and heats water to produce steam. The pressurized steam is then usually fed to a multi-stage steam turbine . After the steam turbine has expanded and partially condensed the steam, the remaining vapor is condensed in

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1320-479: A nuclear station is smaller than the fuel cost for operation of coal or gas plants. Since most of the cost of nuclear power plant is capital cost, there is almost no cost saving by running it at less than full capacity. Nuclear power plants are routinely used in load following mode on a large scale in France, although "it is generally accepted that this is not an ideal economic situation for nuclear stations". Unit A at

1430-506: A number of long-established projects are struggling to find financing, notably Belene in Bulgaria and the additional reactors at Cernavodă in Romania , and some potential backers have pulled out. Where cheap gas is available and its future supply relatively secure, this also poses a major problem for nuclear projects. Analysis of the economics of nuclear power must take into account who bears

1540-444: A previous goal aimed to reduce nuclear electricity generation share to lower than fifty percent by 2025, this target was postponed to 2035 in 2019 and ultimately discarded in 2023. Russia continues to export the most nuclear power plants in the world, with projects across various countries: as of July 2023, Russia was constructing 19 out of 22 reactors constructed by foreign vendors; however, some exporting projects were canceled due to

1650-559: A set of tubes in the furnace. Here the steam picks up more energy from hot flue gases outside the tubing, and its temperature is now superheated above the saturation temperature. The superheated steam is then piped through the main steam lines to the valves before the high-pressure turbine. Nuclear-powered steam plants do not have such sections but produce steam at essentially saturated conditions. Experimental nuclear plants were equipped with fossil-fired superheaters in an attempt to improve overall plant operating cost. The condenser condenses

1760-587: A significantly different evaluation of the economics of new nuclear power stations. Following the 2011 Fukushima nuclear accident in Japan , costs are likely to go up for currently operating and new nuclear power stations, due to increased requirements for on-site spent fuel management and elevated design basis threats. However many designs, such as the currently under construction AP1000, use passive nuclear safety cooling systems, unlike those of Fukushima I which required active cooling systems, which largely eliminates

1870-413: A slight decrease from the 2653 TWh produced in 2021. Thirteen countries generated at least one-quarter of their electricity from nuclear sources. Notably, France relies on nuclear energy for about 70% of its electricity needs, while Ukraine , Slovakia , Belgium , and Hungary source around half their power from nuclear. Japan , which previously depended on nuclear for over a quarter of its electricity,

1980-427: A small enough volume to become supercritical. Most reactors require continuous temperature control to prevent a core meltdown , which has occurred on a few occasions through accident or natural disaster, releasing radiation and making the surrounding area uninhabitable. Plants must be defended against theft of nuclear material and attack by enemy military planes or missiles. The most serious accidents to date have been

2090-523: A specific type of large heat exchanger used in a pressurized water reactor (PWR) to thermally connect the primary (reactor plant) and secondary (steam plant) systems, which generates steam. In a boiling water reactor (BWR), no separate steam generator is used and water boils in the reactor core. In some industrial settings, there can also be steam-producing heat exchangers called heat recovery steam generators (HRSG) which utilize heat from some industrial process, most commonly utilizing hot exhaust from

2200-423: A stationary stator and a spinning rotor , each containing miles of heavy copper conductor. There is generally no permanent magnet , thus preventing black starts . In operation it generates up to 21,000 amperes at 24,000 volts AC (504 MWe) as it spins at either 3,000 or 3,600 rpm , synchronized to the power grid . The rotor spins in a sealed chamber cooled with hydrogen gas, selected because it has

2310-482: A three-year research study of offshore floating nuclear power generation. In October 2022, NuScale Power and Canadian company Prodigy announced a joint project to bring a North American small modular reactor based floating plant to market. The economics of nuclear power plants is a controversial subject, and multibillion-dollar investments ride on the choice of an energy source. Nuclear power stations typically have high capital costs, but low direct fuel costs, with

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2420-406: A trip-out are avoided by flushing out such gases from the combustion zone before igniting the coal. The steam drum (as well as the superheater coils and headers) have air vents and drains needed for initial start up. Fossil fuel power stations often have a superheater section in the steam generating furnace. The steam passes through drying equipment inside the steam drum on to the superheater,

2530-414: A turbine, where it rotates the turbine's blades. The rotating turbine is mechanically connected to an electric generator which converts rotary motion into electricity. Fuels such as natural gas or oil can also be burnt directly in gas turbines ( internal combustion ), skipping the steam generation step. These plants can be of the open cycle or the more efficient combined cycle type. The majority of

2640-478: A typical late 20th-century power station, superheated steam from the boiler is delivered through 14–16-inch-diameter (360–410 mm) piping at 2,400 psi (17 MPa; 160 atm) and 1,000 °F (540 °C) to the high-pressure turbine, where it falls in pressure to 600 psi (4.1 MPa; 41 atm) and to 600 °F (320 °C) in temperature through the stage. It exits via 24–26-inch-diameter (610–660 mm) cold reheat lines and passes back into

2750-580: A worldwide perspective, long-term waste storage costs are uncertain. Construction, or capital cost aside, measures to mitigate global warming such as a carbon tax or carbon emissions trading , increasingly favor the economics of nuclear power. Further efficiencies are hoped to be achieved through more advanced reactor designs, Generation III reactors promise to be at least 17% more fuel efficient, and have lower capital costs, while Generation IV reactors promise further gains in fuel efficiency and significant reductions in nuclear waste. In Eastern Europe,

2860-480: Is about 1/3 of solar and 1/45 of natural gas and 1/75 of coal . Newer models, like HPR1000 , produce even less carbon dioxide during the whole operating life, as little as 1/8 of power plants using gen II reactors for 1.31g/kWh. Thermal power station A thermal power station , also known as a thermal power plant , is a type of power station in which the heat energy generated from various fuel sources (e.g., coal , natural gas , nuclear fuel , etc.)

2970-429: Is also dosed with pH control agents such as ammonia or morpholine to keep the residual acidity low and thus non-corrosive. The boiler is a rectangular furnace about 50 feet (15 m) on a side and 130 feet (40 m) tall. Its walls are made of a web of high pressure steel tubes about 2.3 inches (58 mm) in diameter. Fuel such as pulverized coal is air-blown into the furnace through burners located at

3080-520: Is anticipated to resume similar levels of nuclear energy utilization. Over the last 15 years, the United States has seen a significant improvement in the operational performance of its nuclear power plants, enhancing their utilization and efficiency, adding the output equivalent to 19 new 1000 MWe reactors without actual construction. In France, nuclear power plants still produce over sixty percent of this country's total power generation in 2022. While

3190-503: Is being designed to last 100 years. One of the major limiting wear factors is the deterioration of the reactor's pressure vessel under the action of neutron bombardment, however in 2018 Rosatom announced it had developed a thermal annealing technique for reactor pressure vessels which ameliorates radiation damage and extends service life by between 15 and 30 years. Nuclear stations are used primarily for base load because of economic considerations. The fuel cost of operations for

3300-399: Is converted to electrical energy . The heat from the source is converted into mechanical energy using a thermodynamic power cycle (such as a Diesel cycle , Rankine cycle , Brayton cycle , etc.). The most common cycle involves a working fluid (often water) heated and boiled under high pressure in a pressure vessel to produce high-pressure steam. This high pressure-steam is then directed to

3410-473: Is expensive and has seldom been implemented. Government regulations and international agreements are being enforced to reduce harmful emissions and promote cleaner power generation. Almost all coal-fired power stations , petroleum, nuclear , geothermal , solar thermal electric , and waste incineration plants , as well as all natural gas power stations are thermal. Natural gas is frequently burned in gas turbines as well as boilers . The waste heat from

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3520-431: Is found in two different isotopes : uranium-238 (U-238), accounting for 99.3% and uranium-235 (U-235) accounting for about 0.7%. U-238 has 146 neutrons and U-235 has 143 neutrons. Different isotopes have different behaviors. For instance, U-235 is fissile which means that it is easily split and gives off a lot of energy making it ideal for nuclear energy. On the other hand, U-238 does not have that property despite it being

3630-474: Is limited, and governed by the laws of thermodynamics . The Carnot efficiency dictates that higher efficiencies can be attained by increasing the temperature of the steam. Sub-critical pressure fossil fuel power stations can achieve 36–40% efficiency. Supercritical designs have efficiencies in the low to mid 40% range, with new "ultra critical" designs using pressures above 4,400 psi (30 MPa) and multiple stage reheat reaching 45–48% efficiency. Above

3740-476: Is returned to the downcomers and the steam is passed through a series of steam separators and dryers that remove water droplets from the steam. The dry steam then flows into the superheater coils. The boiler furnace auxiliary equipment includes coal feed nozzles and igniter guns, soot blowers , water lancing, and observation ports (in the furnace walls) for observation of the furnace interior. Furnace explosions due to any accumulation of combustible gases after

3850-464: Is separated from the water inside a drum at the top of the furnace. The saturated steam is introduced into superheat pendant tubes that hang in the hottest part of the combustion gases as they exit the furnace. Here the steam is superheated to 1,000 °F (540 °C) to prepare it for the turbine. Plants that use gas turbines to heat the water for conversion into steam use boilers known as heat recovery steam generators (HRSG). The exhaust heat from

3960-465: Is the air-cooled condenser . The process is similar to that of a radiator and fan. Exhaust heat from the low-pressure section of a steam turbine runs through the condensing tubes, the tubes are usually finned and ambient air is pushed through the fins with the help of a large fan. The steam condenses to water to be reused in the water-steam cycle. Air-cooled condensers typically operate at a higher temperature than water-cooled versions. While saving water,

4070-429: Is the only nuclear facility that does not use a natural body of water for cooling, instead it uses treated sewage from the greater Phoenix metropolitan area. The water coming from the cooling body of water is either pumped back to the water source at a warmer temperature or returns to a cooling tower where it either cools for more uses or evaporates into water vapor that rises out the top of the tower. The water level in

4180-547: Is used to generate steam that drives a steam turbine connected to a generator that produces electricity . As of September 2023 , the International Atomic Energy Agency reported that there were 410 nuclear power reactors in operation in 32 countries around the world, and 57 nuclear power reactors under construction. Building a nuclear power plant often spans five to ten years, which can accrue significant financial costs, depending on how

4290-402: The "11e Choc" ( 11e Bataillon Parachutiste de Choc , 11th Shock Parachutist Battalion, later 11th Shock Parachutist Demi-Brigade) , created in 1946. The 11e Choc was disbanded in 1963 because its officers were suspected to be French Algeria supporters. Consequently, its missions were partly given to military special forces units, especially the 1st Marine Infantry Parachute Regiment . After

4400-486: The BWR , the steam is directed into the suppression chamber and condenses there. The chambers on a heat exchanger are connected to the intermediate cooling circuit. The main condenser is a large cross-flow shell and tube heat exchanger that takes wet vapor, a mixture of liquid water and steam at saturation conditions, from the turbine-generator exhaust and condenses it back into sub-cooled liquid water so it can be pumped back to

4510-786: The Manhattan Elevated Railway . Each of seventeen units weighed about 500 tons and was rated 6000 kilowatts; a contemporary turbine set of similar rating would have weighed about 20% as much. The energy efficiency of a conventional thermal power station is defined as saleable energy produced as a percent of the heating value of the fuel consumed. A simple cycle gas turbine achieves energy conversion efficiencies from 20 to 35%. Typical coal-based power plants operating at steam pressures of 170 bar and 570 °C run at efficiency of 35 to 38%, with state-of-the-art fossil fuel plants at 46% efficiency. Combined-cycle systems can reach higher values. As with all heat engines, their efficiency

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4620-491: The Russian invasion of Ukraine . Meanwhile, China continues to advance in nuclear energy: having 25 reactors under construction by late 2023, China is the country with the most reactors being built at one time in the world. Nuclear decommissioning is the dismantling of a nuclear power station and decontamination of the site to a state no longer requiring protection from radiation for the general public. The main difference from

4730-590: The SDECE in 1971. The current action division originated from the SDECE 's action service ( Service Action or SA. Service Action is still commonly used). The action division has a "pool" of paramilitary operatives coming mainly from the French Army , often at least from the paras, and some from special forces. Since the early 1980s, the service action has been divided into three main parts: commandos, combat divers and air support. The commandos were originally chunked in

4840-769: The Soviet Union . The world's first full scale power station, Calder Hall in the United Kingdom , opened on October 17, 1956 and was also meant to produce plutonium . The world's first full scale power station solely devoted to electricity production was the Shippingport Atomic Power Station in Pennsylvania , United States, which was connected to the grid on December 18, 1957. The conversion to electrical energy takes place indirectly, as in conventional thermal power stations. The fission in

4950-656: The UAE launched the Arab region's first-ever nuclear energy plant. Unit 1 of the Barakah plant in the Al Dhafrah region of Abu Dhabi commenced generating heat on the first day of its launch, while the remaining 3 Units are being built. However, Nuclear Consulting Group head, Paul Dorfman, warned the Gulf nation's investment into the plant as a risk "further destabilizing the volatile Gulf region, damaging

5060-403: The critical point for water of 705 °F (374 °C) and 3,212 psi (22.15 MPa), there is no phase transition from water to steam, but only a gradual decrease in density . Currently most nuclear power stations must operate below the temperatures and pressures that coal-fired plants do, in order to provide more conservative safety margins within the systems that remove heat from

5170-647: The sinking of the Rainbow Warrior in 1985, the "11e Choc" was re-raised in 1985 as the 11th Shock Parachutist Regiment. The unit was disbanded in 1993 among other various changes of French armed forces following the end of the cold war. DGSE operatives are since based in three "training centres" which compose the Centre d'Instruction des Réservistes Parachutistes (CIRP, "Paratrooper Reservist Instruction Centre"): Commando Hubert originally included servicemen from both French Navy and Army. The unit soon split in two,

5280-552: The steam boiler is a means of transferring heat energy from the burning fuel to the mechanical energy of the spinning steam turbine . The total feed water consists of recirculated condensate water and purified makeup water . Because the metallic materials it contacts are subject to corrosion at high temperatures and pressures, the makeup water is highly purified before use. A system of water softeners and ion exchange demineralizes produces water so pure that it coincidentally becomes an electrical insulator , with conductivity in

5390-409: The vapor pressure of water is much less than atmospheric pressure, the condenser generally works under vacuum . Thus leaks of non-condensible air into the closed loop must be prevented. Typically the cooling water causes the steam to condense at a temperature of about 25 °C (77 °F) and that creates an absolute pressure in the condenser of about 2–7  kPa (0.59–2.07  inHg ), i.e.

5500-531: The 18th century, with notable improvements being made by James Watt . When the first commercially developed central electrical power stations were established in 1882 at Pearl Street Station in New York and Holborn Viaduct power station in London, reciprocating steam engines were used. The development of the steam turbine in 1884 provided larger and more efficient machine designs for central generating stations. By 1892

5610-424: The 1970s and 1980s, when it "reached an intensity unprecedented in the history of technology controversies," in some countries. Proponents argue that nuclear power is a sustainable energy source which reduces carbon emissions and can increase energy security if its use supplants a dependence on imported fuels. Proponents advance the notion that nuclear power produces virtually no air pollution, in contrast to

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5720-485: The 1979 Three Mile Island accident , the 1986 Chernobyl disaster , and the 2011 Fukushima Daiichi nuclear disaster , corresponding to the beginning of the operation of generation II reactors . Professor of sociology Charles Perrow states that multiple and unexpected failures are built into society's complex and tightly coupled nuclear reactor systems. Such accidents are unavoidable and cannot be designed around. An interdisciplinary team from MIT has estimated that given

5830-743: The 20th century . Shipboard power stations usually directly couple the turbine to the ship's propellers through gearboxes. Power stations in such ships also provide steam to smaller turbines driving electric generators to supply electricity. Nuclear marine propulsion is, with few exceptions, used only in naval vessels. There have been many turbo-electric ships in which a steam-driven turbine drives an electric generator which powers an electric motor for propulsion . Cogeneration plants, often called combined heat and power (CHP) facilities, produce both electric power and heat for process heat or space heating, such as steam and hot water. The reciprocating steam engine has been used to produce mechanical power since

5940-559: The Brussels supplementary convention, and the Vienna Convention on Civil Liability for Nuclear Damage . However states with a majority of the world's nuclear power stations, including the U.S., Russia, China and Japan, are not party to international nuclear liability conventions. The nuclear power debate about the deployment and use of nuclear fission reactors to generate electricity from nuclear fuel for civilian purposes peaked during

6050-575: The Commandos Marine. The air support of DGSE operations is provided by a French Air Force unit, the Groupe Aérien Mixte 00.056 (GAM 56) "Vaucluse" , heir of a Free French Forces special duties flight . This unit received the Croix de la Valeur Militaire with bronze palms on 1 June 2012, for having "particularly distinguished itself in a number of very sensitive recent engagements". Furthermore,

6160-989: The Otto or Diesel cycles. In the Rankine cycle, the low-pressure exhaust from the turbine enters a steam condenser where it is cooled to produce hot condensate which is recycled to the heating process to generate even more high pressure steam. The design of thermal power stations depends on the intended energy source. In addition to fossil and nuclear fuel , some stations use geothermal power , solar energy , biofuels , and waste incineration . Certain thermal power stations are also designed to produce heat for industrial purposes, provide district heating , or desalinate water , in addition to generating electrical power. Emerging technologies such as supercritical and ultra-supercritical thermal power stations operate at higher temperatures and pressures for increased efficiency and reduced emissions. Cogeneration or CHP (Combined Heat and Power) technology,

6270-494: The Service Action killed 135 people, sank six ships and destroyed two aeroplanes. The action division's directors were: Nuclear power plant A nuclear power plant ( NPP ), also known as a nuclear power station ( NPS ), nuclear generating station ( NGS ) or atomic power station ( APS ) is a thermal power station in which the heat source is a nuclear reactor . As is typical of thermal power stations, heat

6380-498: The United States are about 90 percent efficient in converting the energy of falling water into electricity while the efficiency of a wind turbine is limited by Betz's law , to about 59.3%, and actual wind turbines show lower efficiency. The direct cost of electric energy produced by a thermal power station is the result of cost of fuel, capital cost for the plant, operator labour, maintenance, and such factors as ash handling and disposal. Indirect social or environmental costs, such as

6490-486: The air in the air preheater for better economy. Secondary air is mixed with the coal/primary air flow in the burners. The induced draft fan assists the FD fan by drawing out combustible gases from the furnace, maintaining slightly below atmospheric pressure in the furnace to avoid leakage of combustion products from the boiler casing. A steam turbine generator consists of a series of steam turbines interconnected to each other and

6600-614: The army soldiers being transferred to the Centre d'Instruction des Nageurs de Combat (CINC, Combat Divers Training Centre, nicknamed Ajax) assigned to "11e Choc" . In the aftermath of the disastrous Rainbow Warrior affair, the CINC was officially disbanded, and the DGSE combat divers were transferred in the CPEOM. Commando Hubert remains as the combat diver component of the French naval special operation forces,

6710-400: The atmosphere, or once-through cooling (OTC) water from a river, lake or ocean. In the United States, about two-thirds of power plants use OTC systems, which often have significant adverse environmental impacts. The impacts include thermal pollution and killing large numbers of fish and other aquatic species at cooling water intakes . The heat absorbed by the circulating cooling water in

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6820-623: The battalion and started training his men in " carrying out what was then called 'psychological warfare', everywhere where necessary, and notably in Indochina (...) I prepared my men for clandestine operations, airborne or otherwise, which could range from exploding buildings, sabotage or elimination of enemies... a little bit like what I had learnt in England. " According to Constantin Melnik , then supervisor of secret services for Michel Debré , in 1960 alone,

6930-433: The boiler, where the steam is reheated in special reheat pendant tubes back to 1,000 °F (540 °C). The hot reheat steam is conducted to the intermediate-pressure turbine, where it falls in both temperature and pressure and exits directly to the long-bladed low-pressure turbines and finally exits to the condenser. The generator, typically about 30 feet (9 m) long and 12 feet (3.7 m) in diameter, contains

7040-552: The chief viable alternative of fossil fuel. Proponents also believe that nuclear power is the only viable course to achieve energy independence for most Western countries. They emphasize that the risks of storing waste are small and can be further reduced by using the latest technology in newer reactors, and the operational safety record in the Western world is excellent when compared to the other major kinds of power plants. Opponents say that nuclear power poses many threats to people and

7150-443: The condenser tubes must also be removed to maintain the ability of the water to cool as it circulates. This is done by pumping the warm water from the condenser through either natural draft, forced draft or induced draft cooling towers (as seen in the adjacent image) that reduce the temperature of the water by evaporation, by about 11 to 17 °C (52 to 63 °F)—expelling waste heat to the atmosphere. The circulation flow rate of

7260-519: The cooling water in a 500 MW unit is about 14.2 m /s (500 ft /s or 225,000 US gal/min) at full load. The condenser tubes are typically made stainless steel or other alloys to resist corrosion from either side. Nevertheless, they may become internally fouled during operation by bacteria or algae in the cooling water or by mineral scaling, all of which inhibit heat transfer and reduce thermodynamic efficiency . Many plants include an automatic cleaning system that circulates sponge rubber balls through

7370-485: The costs of fuel extraction, processing, use and spent fuel storage internalized costs. Therefore, comparison with other power generation methods is strongly dependent on assumptions about construction timescales and capital financing for nuclear stations. Cost estimates take into account station decommissioning and nuclear waste storage or recycling costs in the United States due to the Price Anderson Act . With

7480-424: The destruction of a turbine in operation from flying towards the reactor. In the case of a pressurized water reactor, the steam turbine is separated from the nuclear system. To detect a leak in the steam generator and thus the passage of radioactive water at an early stage, an activity meter is mounted to track the outlet steam of the steam generator. In contrast, boiling water reactors pass radioactive water through

7590-458: The dismantling of other power stations is the presence of radioactive material that requires special precautions to remove and safely relocate to a waste repository. Decommissioning involves many administrative and technical actions. It includes all clean-up of radioactivity and progressive demolition of the station. Once a facility is decommissioned, there should no longer be any danger of a radioactive accident or to any persons visiting it. After

7700-411: The economic value of environmental impacts, or environmental and health effects of the complete fuel cycle and plant decommissioning, are not usually assigned to generation costs for thermal stations in utility practice, but may form part of an environmental impact assessment. Those indirect costs belong to the broader concept of externalities . In the nuclear plant field, steam generator refers to

7810-472: The efficiency of the cycle is reduced (resulting in more carbon dioxide per megawatt-hour of electricity). From the bottom of the condenser, powerful condensate pumps recycle the condensed steam (water) back to the water/steam cycle. Power station furnaces may have a reheater section containing tubes heated by hot flue gases outside the tubes. Exhaust steam from the high-pressure turbine is passed through these heated tubes to collect more energy before driving

7920-534: The energy-intensive stages of the nuclear fuel chain are considered, from uranium mining to nuclear decommissioning , nuclear power is not a low-carbon electricity source despite the possibility of refinement and long-term storage being powered by a nuclear facility. Those countries that do not contain uranium mines cannot achieve energy independence through existing nuclear power technologies. Actual construction costs often exceed estimates, and spent fuel management costs are difficult to define. On 1 August 2020,

8030-402: The environment and raising the possibility of nuclear proliferation." Nuclear power plants do not produce greenhouse gases during operation. Older nuclear power plants, like ones using second-generation reactors , produce approximately the same amount of carbon dioxide during the whole life cycle of nuclear power plants for an average of about 11g/kWh, as much power generated by wind , which

8140-775: The environment, and that costs do not justify benefits. Threats include health risks and environmental damage from uranium mining , processing and transport, the risk of nuclear weapons proliferation or sabotage, and the problem of radioactive nuclear waste . Another environmental issue is discharge of hot water into the sea. The hot water modifies the environmental conditions for marine flora and fauna. They also contend that reactors themselves are enormously complex machines where many things can and do go wrong, and there have been many serious nuclear accidents . Critics do not believe that these risks can be reduced through new technology , despite rapid advancements in containment procedures and storage methods. Opponents argue that when all

8250-411: The environment. In addition, many reactors are equipped with a dome of concrete to protect the reactor against both internal casualties and external impacts. The purpose of the steam turbine is to convert the heat contained in steam into mechanical energy. The engine house with the steam turbine is usually structurally separated from the main reactor building. It is aligned so as to prevent debris from

8360-513: The expected growth of nuclear power from 2005 to 2055, at least four serious nuclear accidents would be expected in that period. The MIT study does not take into account improvements in safety since 1970. Nuclear power works under an insurance framework that limits or structures accident liabilities in accordance with the Paris Convention on Third Party Liability in the Field of Nuclear Energy ,

8470-421: The four corners, or along one wall, or two opposite walls, and it is ignited to rapidly burn, forming a large fireball at the center. The thermal radiation of the fireball heats the water that circulates through the boiler tubes near the boiler perimeter. The water circulation rate in the boiler is three to four times the throughput. As the water in the boiler circulates it absorbs heat and changes into steam. It

8580-403: The gas turbines is used to make superheated steam that is then used in a conventional water-steam generation cycle, as described in the gas turbine combined-cycle plants section. The water enters the boiler through a section in the convection pass called the economizer . From the economizer it passes to the steam drum and from there it goes through downcomers to inlet headers at the bottom of

8690-611: The highest known heat transfer coefficient of any gas and for its low viscosity , which reduces windage losses. This system requires special handling during startup, with air in the chamber first displaced by carbon dioxide before filling with hydrogen. This ensures that a highly explosive hydrogen– oxygen environment is not created. The power grid frequency is 60 Hz across North America and 50 Hz in Europe , Oceania , Asia ( Korea and parts of Japan are notable exceptions), and parts of Africa . The desired frequency affects

8800-406: The hot coolant is used as a heat source for a boiler, and the pressurized steam from that drives one or more steam turbine driven electrical generators . In the event of an emergency, safety valves can be used to prevent pipes from bursting or the reactor from exploding. The valves are designed so that they can derive all of the supplied flow rates with little increase in pressure. In the case of

8910-517: The initial investments are financed. Because of this high construction cost and lower operations, maintenance, and fuel costs, nuclear plants are usually used for base load generation, because this maximizes the hours over which the fixed cost of construction can be amortized. Nuclear power plants have a carbon footprint comparable to that of renewable energy such as solar farms and wind farms , and much lower than fossil fuels such as natural gas and coal . Nuclear power plants are among

9020-428: The intermediate and then low-pressure turbines. External fans are provided to give sufficient air for combustion. The Primary air fan takes air from the atmosphere and, first warms the air in the air preheater for better economy. Primary air then passes through the coal pulverizers, and carries the coal dust to the burners for injection into the furnace. The Secondary air fan takes air from the atmosphere and, first warms

9130-450: The local economy by creating jobs in construction, maintenance, and fuel extraction industries. On the other hand, burning of fossil fuels releases greenhouse gases (contributing to climate change) and air pollutants such as sulfur oxides and nitrogen oxides (leading to acid rain and respiratory diseases). Carbon capture and storage (CCS) technology can reduce the greenhouse gas emissions of fossil-fuel-based thermal power stations, however it

9240-417: The middle of this series of feedwater heaters, and before the second stage of pressurization, the condensate plus the makeup water flows through a deaerator that removes dissolved air from the water, further purifying and reducing its corrosiveness. The water may be dosed following this point with hydrazine , a chemical that removes the remaining oxygen in the water to below 5 parts per billion (ppb). It

9350-560: The naval ship Alizé can provide support from the Navy to the benefit of the DGSE. After the Second World War , Colonel Jacques Morlanne used a list of former SOE operatives to create a " Service Action " for the SDECE . In 1947, Morlanne sent captain Edgar Mautaint at Montlouis to create the 11e bataillon parachutiste de choc . In July 1947, Paul Aussaresses took over command of

9460-586: The need to spend more on redundant back up safety equipment. According to the World Nuclear Association , as of March 2020: The Russian state nuclear company Rosatom is the largest player in international nuclear power market, building nuclear plants around the world. Whereas Russian oil and gas were subject to international sanctions after the Russian full-scale invasion of Ukraine in February 2022, Rosatom

9570-473: The now decommissioned German Biblis Nuclear Power Plant was designed to modulate its output 15% per minute between 40% and 100% of its nominal power. Russia has led in the practical development of floating nuclear power stations , which can be transported to the desired location and occasionally relocated or moved for easier decommissioning. In 2022, the United States Department of Energy funded

9680-444: The nuclear fuel. This, in turn, limits their thermodynamic efficiency to 30–32%. Some advanced reactor designs being studied, such as the very-high-temperature reactor , Advanced Gas-cooled Reactor , and supercritical water reactor , would operate at temperatures and pressures similar to current coal plants, producing comparable thermodynamic efficiency. The energy of a thermal power station not utilized in power production must leave

9790-630: The plant in the form of heat to the environment. This waste heat can go through a condenser and be disposed of with cooling water or in cooling towers . If the waste heat is instead used for district heating , it is called cogeneration . An important class of thermal power station is that associated with desalination facilities; these are typically found in desert countries with large supplies of natural gas , and in these plants freshwater production and electricity are equally important co-products. Other types of power stations are subject to different efficiency limitations. Most hydropower stations in

9900-474: The prospect that all spent nuclear fuel could potentially be recycled by using future reactors, generation IV reactors are being designed to completely close the nuclear fuel cycle . However, up to now, there has not been any actual bulk recycling of waste from a NPP, and on-site temporary storage is still being used at almost all plant sites due to construction problems for deep geological repositories . Only Finland has stable repository plans, therefore from

10010-405: The range of 0.3–1.0 microsiemens per centimeter. The makeup water in a 500 MWe plant amounts to perhaps 120 US gallons per minute (7.6 L/s) to replace water drawn off from the boiler drums for water purity management, and to also offset the small losses from steam leaks in the system. The feed water cycle begins with condensate water being pumped out of the condenser after traveling through

10120-427: The reactor by the condensate and feedwater pumps. In the main condenser, the wet vapor turbine exhaust come into contact with thousands of tubes that have much colder water flowing through them on the other side. The cooling water typically come from a natural body of water such as a river or lake. Palo Verde Nuclear Generating Station , located in the desert about 97 kilometres (60 mi) west of Phoenix, Arizona,

10230-507: The remaining energy. The entire rotating mass may be over 200 metric tons and 100 feet (30 m) long. It is so heavy that it must be kept turning slowly even when shut down (at 3 rpm ) so that the shaft will not bow even slightly and become unbalanced. This is so important that it is one of only six functions of blackout emergency power batteries on site. (The other five being emergency lighting , communication , station alarms, generator hydrogen seal system, and turbogenerator lube oil.) For

10340-540: The risks of future uncertainties. To date all operating nuclear power stations were developed by state-owned or regulated utilities where many of the risks associated with construction costs, operating performance, fuel price, and other factors were borne by consumers rather than suppliers. Many countries have now liberalized the electricity market where these risks and the risk of cheaper competitors emerging before capital costs are recovered, are borne by station suppliers and operators rather than consumers, which leads to

10450-632: The safest modes of electricity generation, comparable to solar and wind power plants. The first time that heat from a nuclear reactor was used to generate electricity was on December 21, 1951, at the Experimental Breeder Reactor I , powering four light bulbs. On June 27, 1954, the world's first nuclear power station to generate electricity for a power grid , the Obninsk Nuclear Power Plant , commenced operations in Obninsk , in

10560-407: The same element. Different isotopes also have different half-lives . U-238 has a longer half-life than U-235, so it takes longer to decay over time. This also means that U-238 is less radioactive than U-235. Since nuclear fission creates radioactivity, the reactor core is surrounded by a protective shield. This containment absorbs radiation and prevents radioactive material from being released into

10670-686: The simultaneous production of electricity and useful heat from the same fuel source, improves the overall efficiency by using waste heat for heating purposes. Older, less efficient thermal power stations are being decommissioned or adapted to use cleaner and renewable energy sources. Thermal power stations produce 70% of the world's electricity. They often provide reliable, stable, and continuous baseload power supply essential for economic growth. They ensure energy security by maintaining grid stability, especially in regions where they complement intermittent renewable energy sources dependent on weather conditions. The operation of thermal power stations contributes to

10780-460: The steam from the exhaust of the turbine into liquid to allow it to be pumped. If the condenser can be made cooler, the pressure of the exhaust steam is reduced and efficiency of the cycle increases. The surface condenser is a shell and tube heat exchanger in which cooling water is circulated through the tubes. The exhaust steam from the low-pressure turbine enters the shell, where it is cooled and converted to condensate (water) by flowing over

10890-693: The steam generator and the nuclear reactor is controlled using the feedwater system. The feedwater pump has the task of taking the water from the condensate system, increasing the pressure and forcing it into either the steam generators—in the case of a pressurized water reactor — or directly into the reactor, for boiling water reactors . Continuous power supply to the plant is critical to ensure safe operation. Most nuclear stations require at least two distinct sources of offsite power for redundancy. These are usually provided by multiple transformers that are sufficiently separated and can receive power from multiple transmission lines. In addition, in some nuclear stations,

11000-487: The steam turbine, so the turbine is kept as part of the radiologically controlled area of the nuclear power station. The electric generator converts mechanical power supplied by the turbine into electrical power. Low-pole AC synchronous generators of high rated power are used. A cooling system removes heat from the reactor core and transports it to another area of the station, where the thermal energy can be harnessed to produce electricity or to do other useful work. Typically

11110-420: The steam turbines. The condensate flow rate at full load in a 500 MW plant is about 6,000 US gallons per minute (400 L/s). The water is usually pressurized in two stages, and typically flows through a series of six or seven intermediate feed water heaters, heated up at each point with steam extracted from an appropriate extraction connection on the turbines and gaining temperature at each stage. Typically, in

11220-433: The temperature beyond the turbine limits during winter, causing excessive condensation in the turbine). Plants operating in hot climates may have to reduce output if their source of condenser cooling water becomes warmer; unfortunately this usually coincides with periods of high electrical demand for air conditioning . The condenser generally uses either circulating cooling water from a cooling tower to reject waste heat to

11330-455: The tubes as shown in the adjacent diagram. Such condensers use steam ejectors or rotary motor -driven exhausts for continuous removal of air and gases from the steam side to maintain vacuum . For best efficiency, the temperature in the condenser must be kept as low as practical in order to achieve the lowest possible pressure in the condensing steam. Since the condenser temperature can almost always be kept significantly below 100 °C where

11440-452: The tubes to scrub them clean without the need to take the system off-line. The cooling water used to condense the steam in the condenser returns to its source without having been changed other than having been warmed. If the water returns to a local water body (rather than a circulating cooling tower), it is often tempered with cool 'raw' water to prevent thermal shock when discharged into that body of water. Another form of condensing system

11550-477: The turbine generator can power the station's loads while the station is online, without requiring external power. This is achieved via station service transformers which tap power from the generator output before they reach the step-up transformer. Nuclear power plants generate approximately 10% of global electricity, sourced from around 440 reactors worldwide. They are recognized as a significant provider of low-carbon electricity , accounting for about one-quarter of

11660-432: The turbine was considered a better alternative to reciprocating engines; turbines offered higher speeds, more compact machinery, and stable speed regulation allowing for parallel synchronous operation of generators on a common bus. After about 1905, turbines entirely replaced reciprocating engines in almost all large central power stations. The largest reciprocating engine-generator sets ever built were completed in 1901 for

11770-400: The water walls. From these headers the water rises through the water walls of the furnace where some of it is turned into steam and the mixture of water and steam then re-enters the steam drum. This process may be driven purely by natural circulation (because the water is the downcomers is denser than the water/steam mixture in the water walls) or assisted by pumps. In the steam drum, the water

11880-455: The world's supply in this category. As of 2020, nuclear power stood as the second-largest source of low-carbon energy, making up 26% of the total. Nuclear power facilities are active in 32 countries or regions, and their influence extends beyond these nations through regional transmission grids, especially in Europe. In 2022, nuclear power plants generated 2545 terawatt-hours (TWh) of electricity,

11990-433: The world's thermal power stations are driven by steam turbines, gas turbines, or a combination of the two. The efficiency of a thermal power station is determined by how effectively it converts heat energy into electrical energy, specifically the ratio of saleable electricity to the heating value of the fuel used. Different thermodynamic cycles have varying efficiencies, with the Rankine cycle generally being more efficient than

12100-477: Was not targeted by sanctions. However, some countries, especially in Europe, scaled back or cancelled planned nuclear power plants that were to be built by Rosatom. Modern nuclear reactor designs have had numerous safety improvements since the first-generation nuclear reactors. A nuclear power plant cannot explode like a nuclear weapon because the fuel for uranium reactors is not enriched enough, and nuclear weapons require precision explosives to force fuel into

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