A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Sir Charles Parsons in 1884; because the turbine generates rotary motion, it is suited to be used to drive an electrical generator—about 85% of all electricity generation in the United States in the year 2014 was by use of steam turbines. The steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency from the use of multiple stages in the expansion of the steam, which results in a closer approach to the ideal reversible expansion process; the first device that may be classified as a reaction steam turbine was little more than a toy, the classic Aeolipile, described in the 1st century by Hero of Alexandria in Roman Egypt. In 1551, Taqi al-Din in Ottoman Egypt described a steam turbine with the practical application of rotating a spit. Steam turbines were described by the Italian Giovanni Branca and John Wilkins in England.
The devices described by Taqi al-Din and Wilkins are today known as steam jacks. In 1672 an impulse steam turbine driven car was designed by Ferdinand Verbiest. A more modern version of this car was produced some time in the late 18th century by an unknown German mechanic. In 1775 at Soho James Watt designed a reaction turbine, put to work there. In 1827 the Frenchmen Real and Pichon constructed a compound impulse turbine; the modern steam turbine was invented in 1884 by Sir Charles Parsons, whose first model was connected to a dynamo that generated 7.5 kW of electricity. The invention of Parsons' steam turbine made cheap and plentiful electricity possible and revolutionized marine transport and naval warfare. Parsons' design was a reaction type, his patent was the turbine scaled-up shortly after by an American, George Westinghouse. The Parsons turbine turned out to be easy to scale up. Parsons had the satisfaction of seeing his invention adopted for all major world power stations, the size of generators had increased from his first 7.5 kW set up to units of 50,000 kW capacity.
Within Parson's lifetime, the generating capacity of a unit was scaled up by about 10,000 times, the total output from turbo-generators constructed by his firm C. A. Parsons and Company and by their licensees, for land purposes alone, had exceeded thirty million horse-power. A number of other variations of turbines have been developed that work with steam; the de Laval turbine accelerated the steam to full speed before running it against a turbine blade. De Laval's impulse turbine does not need to be pressure-proof, it can operate with any pressure of steam, but is less efficient. Auguste Rateau developed a pressure compounded impulse turbine using the de Laval principle as early as 1896, obtained a US patent in 1903, applied the turbine to a French torpedo boat in 1904, he taught at the École des mines de Saint-Étienne for a decade until 1897, founded a successful company, incorporated into the Alstom firm after his death. One of the founders of the modern theory of steam and gas turbines was Aurel Stodola, a Slovak physicist and engineer and professor at the Swiss Polytechnical Institute in Zurich.
His work Die Dampfturbinen und ihre Aussichten als Wärmekraftmaschinen was published in Berlin in 1903. A further book Dampf und Gas-Turbinen was published in 1922; the Brown-Curtis turbine, an impulse type, developed and patented by the U. S. company International Curtis Marine Turbine Company, was developed in the 1900s in conjunction with John Brown & Company. It was used in John Brown-engined merchant ships and warships, including liners and Royal Navy warships; the present-day manufacturing industry for steam turbines is dominated by Chinese power equipment makers. Harbin Electric, Shanghai Electric, Dongfang Electric, the top three power equipment makers in China, collectively hold a majority stake in the worldwide market share for steam turbines in 2009-10 according to Platts. Other manufacturers with minor market share include Bharat Heavy Electricals Limited, Alstom, General Electric, Doosan Škoda Power, Mitsubishi Heavy Industries, Toshiba; the consulting firm Frost & Sullivan projects that manufacturing of steam turbines will become more consolidated by 2020 as Chinese power manufacturers win increasing business outside of China.
Steam turbines are made in a variety of sizes ranging from small <0.75 kW units used as mechanical drives for pumps and other shaft driven equipment, to 1.5 GW turbines used to generate electricity. There are several classifications for modern steam turbines. Turbine blades are of two basic types and nozzles. Blades move due to the impact of steam on them and their profiles do not converge; this results in a steam velocity drop and no pressure drop as steam moves through the blades. A turbine composed of blades alternating with fixed nozzles is called an impulse turbine, Curtis turbine, Rateau turbine, or Brown-Curtis turbine. Nozzles appear similar to blades; this results in a steam pressure velocity increase as steam moves through the nozzles. Nozzles move due to both the impact of steam on them and the reaction due to the high-velocity steam at the exit. A turbine composed of moving nozzles alternating with fixed nozzles is called a reaction turbine or Parsons turbine. Except for low-power applications, turbine blades are arranged in multiple stages in series, called c
Peach Bottom Nuclear Generating Station
Peach Bottom Atomic Power Station, a nuclear power plant, is located 50 miles southeast of Harrisburg in Peach Bottom Township, York County, Pennsylvania, on the Susquehanna River three miles north of the Maryland border. The Philadelphia Electric Company became one of the pioneers in the commercial nuclear industry when it ordered Peach Bottom 1 in 1958; the U. S.'s first nuclear power plant had gone on line a year earlier. Peach Bottom Unit 1 was an experimental graphite-moderated reactor, it operated from 1966 to 1974. The other two units, General Electric boiling water reactors, placed on-line in 1974, are still in operation on the 620-acre site. Both Units 2 and 3 rated at 3,514 megawatts thermal, equivalent to about 1,180 megawatts of electricity each, were uprated to 4,016 megawatts thermal, equivalent to about 1,382 megawatts net of electricity each in 2018, their licenses run until 2033 and 2034. Peach Bottom is operated by the Exelon and is jointly owned by Exelon and Public Service Enterprise Group Power LLC.
Peach Bottom was one of the plants analyzed in the NUREG-1150 safety analysis study. The Nuclear Regulatory Commission defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of 10 miles, concerned with exposure to, inhalation of, airborne radioactive contamination, an ingestion pathway zone of about 50 miles, concerned with ingestion of food and liquid contaminated by radioactivity; the 2010 U. S. population within 10 miles of Peach Bottom was 46,536, an increase of 7.2 percent in a decade, according to an analysis of U. S. Census data for msnbc.com. The 2010 U. S. population within 50 miles was 5,526,343, an increase of 10.6 percent since 2000. Cities within 50 miles include Baltimore. In 1987, PECO was ordered by the Nuclear Regulatory Commission to indefinitely shutdown Peach Bottom-2 and -3 on March 31 due to operator misconduct, corporate malfeasance and blatant disregard for the health and safety of the area. Infamously, operators were found sleeping on the job, playing video games, engaging in rubber band and paper ball fights, reading unauthorized material.
Among the incidents cited by the NRC: security guards were overworked, one guard was found asleep on the job, 36,000 gallons of "mildly radioactive water" leaked into the Susquehanna River, PECO mislaid data on radioactive waste classification causing misclassification of a waste shipment, a major fire occurred in the maintenance cage of the Unit 3 turbine building on March 4, 1987. Blame was not placed on the operators. "Latent organizational weakness" was targeted by industry regulators alike. INPO President Zack Pate came to the conclusion that “Major changes in the corporate culture at PECO are required.” In September 1988, NRC Chairman Lando Zech told senior management officials of PECO, "Your operators made mistakes, no question about that. Your corporate management problems are just as serious." A culture characterized by low morale and apathy prevailed. By April 1988, this emphasis on mismanagement contributed to the President of PECO resigning as well as to the retirement of the CEO.
Robert P. Crosby became the primary Organization Development influence during the PECO Nuclear turnaround following the Peach Bottom shut down, he used The Interpersonal Gap model by John L. Wallen along with a unique T-group method known as Conflict Management to speed culture change, applied his own version of Daryl Conner's Sponsor Agent Target model to improving and shortening outage management. By 1996, both Limerick and Peach Bottom were designated excellent by INPO, given strong Systematic Assessment of Licensee Performance ratings by the NRC. In 1999, PECO Nuclear eliminated their Organization Development positions as part of cost cutting initiative. Trouble arose again in September 2007, when former employee Kerry Beal videotaped Peach Bottom security guards sleeping on the job. Beal had tried to notify supervisors at Wackenhut Corp. and the US Nuclear Regulatory Commission. He was fired during the Exelon security transition, a decision which made a list of the 101 "dumbest moments in business" in the January 16, 2008 issue of Fortune.
The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Peach Bottom was 1 in 41,667. Exelon Nuclear reactor accidents in the United States Nuclear safety in the United States G4S Secure Solutions List of the largest nuclear power stations in the United States Specific Generalhttps://www.nrc.gov/info-finder/decommissioning/power-reactor/peach-bottom-atomic-power-station-unit.html "Peach Bottom Atomic Power Station, Pennsylvania". Energy Information Administration, U. S. Department of Energy. October 3, 2008. Retrieved 2008-11-18. "Peach Bottom 2 Boiling Water Reactor". Operating Nuclear Power Reactors. U. S. Nuclear Regulatory Commission. February 14, 2008. Retrieved 2008-11-18. "Peach Bottom 3 Boiling Water Reactor". Operating Nuclear Power Reactors. NRC. February 14, 2008. Retrieved 2008-11-18."The Peach Bottom Atomic Energy Station". PSEG Nuclear LLC. 2008. Archived from the original on 2008-06-07. Retrieved 2008-11-18
General Electric Company is an American multinational conglomerate incorporated in New York and headquartered in Boston. As of 2018, the company operates through the following segments: aviation, power, renewable energy, digital industry, additive manufacturing, venture capital and finance and oil and gas. In 2018, GE ranked among the Fortune 500 as the 18th-largest firm in the U. S. by gross revenue. In 2011, GE ranked among the Fortune 20 as the 14th-most profitable company but has since severely underperformed the market as its profitability collapsed. Two employees of GE—Irving Langmuir and Ivar Giaever —have been awarded the Nobel Prize. During 1889, Thomas Edison had business interests in many electricity-related companies including Edison Lamp Company, a lamp manufacturer in East Newark, New Jersey. P. Morgan and the Vanderbilt family for Edison's lighting experiments. In 1889, Morgan & Co. a company founded by J. P. Morgan and Anthony J. Drexel, financed Edison's research and helped merge those companies under one corporation to form Edison General Electric Company, incorporated in New York on April 24, 1889.
The new company acquired Sprague Electric Railway & Motor Company in the same year. In 1880, Gerald Waldo Hart formed the American Electric Company of New Britain, which merged a few years with Thomson-Houston Electric Company, led by Charles Coffin. In 1887, Hart left to become superintendent of the Edison Electric Company of Missouri. General Electric was formed through the 1892 merger of Edison General Electric Company of Schenectady, New York, Thomson-Houston Electric Company of Lynn, with the support of Drexel, Morgan & Co. Both plants continue to operate under the GE banner to this day; the company was incorporated in New York, with the Schenectady plant used as headquarters for many years thereafter. Around the same time, General Electric's Canadian counterpart, Canadian General Electric, was formed. In 1896, General Electric was one of the original 12 companies listed on the newly formed Dow Jones Industrial Average, where it remained a part of the index for 122 years, though not continuously.
In 1911, General Electric absorbed the National Electric Lamp Association into its lighting business. GE established its lighting division headquarters at Nela Park in Ohio; the lighting division has since remained in the same location. Owen D. Young, through GE, founded the Radio Corporation of America in 1919, after purchasing the Marconi Wireless Telegraph Company of America, he aimed to expand international radio communications. GE used RCA as its retail arm for radio sales. In 1926, RCA co-founded the National Broadcasting Company, which built two radio broadcasting networks. In 1930, General Electric was charged with antitrust violations and decided to divest itself of RCA. In 1927, Ernst Alexanderson of GE made the first demonstration of his television broadcasts at his General Electric Realty Plot home at 1132 Adams Rd, New York. On January 13, 1928, he made what was said to be the first broadcast to the public in the United States on GE's W2XAD: the pictures were picked up on 1.5 square inch screens in the homes of four GE executives.
The sound was broadcast on GE's WGY. Experimental television station W2XAD evolved into station WRGB which, along with WGY and WGFM, was owned and operated by General Electric until 1983. Led by Sanford Alexander Moss, GE moved into the new field of aircraft turbo superchargers. GE introduced the first set of superchargers during World War I, continued to develop them during the interwar period. Superchargers became indispensable in the years prior to World War II. GE supplied 300,000 turbo superchargers for use in bomber engines; this work led the U. S. Army Air Corps to select GE to develop the nation's first jet engine during the war; this experience, in turn, made GE a natural selection to develop the Whittle W.1 jet engine, demonstrated in the United States in 1941. GE was ranked ninth among United States corporations in the value of wartime production contracts. Although, their early work with Whittle's designs was handed to Allison Engine Company. GE Aviation emerged as one of the world's largest engine manufacturers, bypassing the British company, Rolls-Royce plc.
Some consumers boycotted GE light bulbs and other products during the 1980s and 1990s. The purpose of the boycott was to protest against GE's role in nuclear weapons production. In 2002, GE acquired the wind power assets of Enron during its bankruptcy proceedings. Enron Wind was the only surviving U. S. manufacturer of large wind turbines at the time, GE increased engineering and supplies for the Wind Division and doubled the annual sales to $1.2 billion in 2003. It acquired ScanWind in 2009. In 2015, GE Power garnered press attention when a model 9FB gas turbine in Texas was shut down for two months due to the break of a turbine blade; this model uses similar blade technology to GE's newest and most efficient model, the 9HA. After the break, GE developed heat treatment methods. Gas turbines represent a significant portion of GE Power's revenue, represent a significant portion of the power generation fleet of several utility companies in the United States. Chubu Electric of Japan and Électricité de France had units that were impacted.
Argonne National Laboratory
Argonne National Laboratory is a science and engineering research national laboratory operated by the University of Chicago Argonne LLC for the United States Department of Energy located in Lemont, outside Chicago. It is the largest national laboratory by scope in the Midwest. Argonne was formed to carry out Enrico Fermi's work on nuclear reactors as part of the Manhattan Project, it was designated as the first national laboratory in the United States on July 1, 1946. In the post-war era the lab focused on non-weapon related nuclear physics and building the first power-producing nuclear reactors, helping design the reactors used by the USA's nuclear navy, a wide variety of similar projects. In 1994 the lab's nuclear mission ended, today it maintains a broad portfolio in basic science research, energy storage and renewable energy, environmental sustainability and national security. UChicago Argonne, LLC, the operator of the laboratory, "brings together the expertise of the University of Chicago with Jacobs Engineering Group Inc."
Argonne is a part of the expanding Illinois Research Corridor. Argonne ran a smaller facility called Argonne National Laboratory-West in Idaho next to the Idaho National Engineering and Environmental Laboratory. In 2005, the two Idaho-based laboratories merged to become the Idaho National Laboratory. Argonne has five main areas of focus; these goals, as stated by the DOE in 2008, consist of: Conducting basic scientific research. Argonne began in 1942 as the "Metallurgical Laboratory" at the University of Chicago, which became part of the Manhattan Project; the Met Lab built Chicago Pile-1, the world's first nuclear reactor, under the stands of a University of Chicago sports stadium. Considered unsafe, in 1943, CP-1 was reconstructed as CP-2, in what is today known as Red Gate Woods but was the Argonne Forest of the Cook County Forest Preserve District near Palos Hills; the lab was named after the surrounding Argonne Forest, which in turn was named after the Forest of Argonne in France where U.
S. troops fought in World War I. Fermi's pile was going to be constructed in the Argonne forest, construction plans were set in motion, but a labor dispute brought the project to a halt. Since speed was paramount, the project was moved to the squash court under Stagg Field, the football field on the campus of the University of Chicago. Fermi told them that he was sure of his calculations, which said that it would not lead to a runaway reaction, which would have contaminated the city. Other activities were added to Argonne over the next five years. On July 1, 1946, the "Metallurgical Laboratory" was formally re-chartered as Argonne National Laboratory for "cooperative research in nucleonics." At the request of the U. S. Atomic Energy Commission, it began developing nuclear reactors for the nation's peaceful nuclear energy program. In the late 1940s and early 1950s, the laboratory moved to a larger location in unincorporated DuPage County and established a remote location in Idaho, called "Argonne-West," to conduct further nuclear research.
In quick succession, the laboratory designed and built Chicago Pile 3, the world's first heavy-water moderated reactor, the Experimental Breeder Reactor I, built in Idaho, which lit a string of four light bulbs with the world's first nuclear-generated electricity in 1951. A complete list of the reactors designed and, in most cases and operated by Argonne can be viewed in the, "Reactors Designed by Argonne" page; the knowledge gained from the Argonne experiments conducted with these reactors 1) formed the foundation for the designs of most of the commercial reactors used throughout the world for electric power generation and 2) inform the current evolving designs of liquid-metal reactors for future commercial power stations. Conducting classified research, the laboratory was secured; such alluring secrecy drew visitors both authorized—including King Leopold III of Belgium and Queen Frederica of Greece—and unauthorized. Shortly past 1 a.m. on February 6, 1951, Argonne guards discovered reporter Paul Harvey near the 10-foot perimeter fence, his coat tangled in the barbed wire.
Searching his car, guards found a prepared four-page broadcast detailing the saga of his unauthorized entrance into a classified "hot zone". He was brought before a federal grand jury on charges of conspiracy to obtain information on national security and transmit it to the public, but was not indicted. Not all nuclear technology went into developing reactors, however. While designing a scanner for reactor fuel elements in 1957, Argonne physicist William Nelson Beck put his own arm inside the scanner and obtained one of the first ultrasound images of the human body. Remote manipulators designed to handle radioactive materials laid the groundwork for more complex machines used to clean up contaminated areas, sealed laboratories or caves. In 1964, the "Janus" reactor opened to study the effects of neutron radiation on biological life, providing research for guidelines on safe exposure levels for workers at power plants and hospitals. Scientists at Argonne pioneered a technique to analyze the moon's surface using alpha radiation, which launched aboard the Surveyor 5 in 1967 and analyzed lunar samples from the Apollo 11 mission.
In addition to nuclear work, the laboratory maintained a
Decay heat is the heat released as a result of radioactive decay. This heat is produced as an effect of radiation on materials: the energy of the alpha, beta or gamma radiation is converted into the thermal movement of atoms. Decay heat occurs from decay of long-lived radioisotopes that are primordially present from the Earth's formation. In nuclear reactor engineering, decay heat continues to be generated after the reactor has been shut down, nuclear chain reactions have been suspended; the decay of the short-lived radioisotopes created in fission continues at high power, for a time after shut down. The major source of heat production in a newly shut down reactor is due to the beta decay of new radioactive elements produced from fission fragments in the fission process. Quantitatively, at the moment of reactor shutdown, decay heat from these radioactive sources is still 6.5% of the previous core power, if the reactor has had a long and steady power history. About 1 hour after shutdown, the decay heat will be about 1.5% of the previous core power.
After a day, the decay heat falls to 0.4%, after a week it will be only 0.2%. Because radioisotopes of all half life lengths are present in nuclear waste, enough decay heat continues to be produced in spent fuel rods to require them to spend a minimum of one year, more 10 to 20 years, in a spent fuel pool of water, before being further processed. However, the heat produced during this time is still only a small fraction of the heat produced in the first week after shutdown. If no cooling system is working to remove the decay heat from a crippled and newly shut down reactor, the decay heat may cause the core of the reactor to reach unsafe temperatures within a few hours or days, depending upon the type of core; these extreme temperatures can lead to minor fuel damage or major core structural damage in a light water reactor or liquid metal fast reactor. Chemical species released from the damaged core material may lead to further explosive reactions which may further damage the reactor. Occurring decay heat is a significant source of the heat in the interior of the Earth.
Radioactive isotopes of uranium and potassium are the primary contributors to this decay heat, this radioactive decay is the primary source of heat from which geothermal energy derives. In a typical nuclear fission reaction, 187 MeV of energy are released instantaneously in the form of kinetic energy from the fission products, kinetic energy from the fission neutrons, instantaneous gamma rays, or gamma rays from the capture of neutrons. An additional 23 MeV of energy are released at some time after fission from the beta decay of fission products. About 10 MeV of the energy released from the beta decay of fission products is in the form of neutrinos, since neutrinos are weakly interacting, this 10 MeV of energy will not be deposited in the reactor core; this results in 13 MeV being deposited in the reactor core from delayed beta decay of fission products, at some time after any given fission reaction has occurred. In a steady state, this heat from delayed fission product beta decay contributes 6.5% of the normal reactor heat output.
When a nuclear reactor has been shut down, nuclear fission is not occurring at a large scale, the major source of heat production will be due to the delayed beta decay of these fission products. For this reason, at the moment of reactor shutdown, decay heat will be about 6.5% of the previous core power if the reactor has had a long and steady power history. About 1 hour after shutdown, the decay heat will be about 1.5% of the previous core power. After a day, the decay heat falls to 0.4%, after a week it will be only 0.2%. The decay heat production rate will continue to decrease over time. An approximation for the decay heat curve valid from 10 seconds to 100 days after shutdown is P P 0 = 0.066 where P is the decay power, P 0 is the reactor power before shutdown, τ is the time since reactor startup and τ s is the time of reactor shutdown measured from the time of startup. For an approach with a more direct physical basis, some models use the fundamental concept of radioactive decay. Used nuclear fuel contains a large number of different isotopes that contribute to decay heat, which are all subject to the radioactive decay law, so some models consider decay heat to be a sum of exponential functions with different decay constants and initial contribution to the heat rate.
A more accurate model would consider the effects of precursors, since many isotopes follow several steps in their radioactive decay chain, the decay of daughter products will have a greater effect longer after shutdown. P P 0 = ∑ i = 1 11 P i e − λ t
A cooling tower is a heat rejection device that rejects waste heat to the atmosphere through the cooling of a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or, in the case of closed circuit dry cooling towers, rely on air to cool the working fluid to near the dry-bulb air temperature. Common applications include cooling the circulating water used in oil refineries and other chemical plants, thermal power stations and HVAC systems for cooling buildings; the classification is based on the type of air induction into the tower: the main types of cooling towers are natural draft and induced draft cooling towers. Cooling towers vary in size from small roof-top units to large hyperboloid structures that can be up to 200 metres tall and 100 metres in diameter, or rectangular structures that can be over 40 metres tall and 80 metres long; the hyperboloid cooling towers are associated with nuclear power plants, although they are used in some coal-fired plants and to some extent in some large chemical and other industrial plants.
Although these large towers are prominent, the vast majority of cooling towers are much smaller, including many units installed on or near buildings to discharge heat from air conditioning. Cooling towers originated in the 19th century through the development of condensers for use with the steam engine. Condensers use cool water, via various means, to condense the steam coming out of the cylinders or turbines; this reduces the back pressure, which in turn reduces the steam consumption, thus the fuel consumption, while at the same time increasing power and recycling boiler-water. However the condensers require an ample supply of cooling water, without; the consumption of cooling water by inland processing and power plants is estimated to reduce power availability for the majority of thermal power plants by 2040–2069. While water usage is not an issue with marine engines, it forms a significant limitation for many land-based systems. By the turn of the 20th century, several evaporative methods of recycling cooling water were in use in areas lacking an established water supply, as well as in urban locations where municipal water mains may not be of sufficient supply.
In areas with available land, the systems took the form of cooling ponds. These early towers were positioned either on the rooftops of buildings or as free-standing structures, supplied with air by fans or relying on natural airflow. An American engineering textbook from 1911 described one design as "a circular or rectangular shell of light plate—in effect, a chimney stack much shortened vertically and much enlarged laterally. At the top is a set of distributing troughs, to which the water from the condenser must be pumped; the first hyperboloid cooling towers were built in 1918 near Heerlen. The first ones in the United Kingdom were built in 1924 at Lister Drive power station in Liverpool, England, to cool water used at a coal-fired electrical power station. An HVAC cooling tower is used to dispose of unwanted heat from a chiller. Water-cooled chillers are more energy efficient than air-cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures. Air-cooled chillers must reject heat at the higher dry-bulb temperature, thus have a lower average reverse-Carnot cycle effectiveness.
In areas with a hot climate, large office buildings and schools use one or more cooling towers as part of their air conditioning systems. Industrial cooling towers are much larger than HVAC towers. HVAC use of a cooling tower pairs the cooling tower with a water-cooled chiller or water-cooled condenser. A ton of air-conditioning is defined as the removal of 12,000 BTU/hour; the equivalent ton on the cooling tower side rejects about 15,000 BTU/hour due to the additional waste heat-equivalent of the energy needed to drive the chiller's compressor. This equivalent ton is defined as the heat rejection in cooling 3 US gallons/minute of water 10 °F, which amounts to 15,000 BTU/hour, assuming a chiller coefficient of performance of 4.0. This COP is equivalent to an energy efficiency ratio of 14. Cooling towers are used in HVAC systems that have multiple water source heat pumps that share a common piping water loop. In this type of system, the water circulating inside the water loop removes heat from the condenser of the heat pumps whenever the heat pumps are working in the cooling mode the externally mounted cooling tower is used to remove heat from the water loop and reject it to the atmosphere.
By contrast, when the heat pumps are working in heating mode, the condensers draw heat out of the loop water and reject it into the space to be heated. When the water loop is being used to supply heat to the building, the cooling tower is shut down, heat is supplied by other means from separate boilers. Industrial cooling towers can be used to remove heat from various sources such as machinery or heated process material; the primary use of large, industrial cooling towe
Integral fast reactor
The integral fast reactor is a design for a nuclear reactor using fast neutrons and no neutron moderator. IFR would breed more fuel and is distinguished by a nuclear fuel cycle that uses reprocessing via electrorefining at the reactor site. IFR development began in 1984 and the U. S. Department of Energy built a prototype, the Experimental Breeder Reactor II. On April 3, 1986, two tests demonstrated the inherent safety of the IFR concept; these tests simulated accidents involving loss of coolant flow. With its normal shutdown devices disabled, the reactor shut itself down safely without overheating anywhere in the system; the IFR project was canceled by the US Congress three years before completion. The proposed Generation IV Sodium-Cooled Fast Reactor is its closest surviving fast breeder reactor design. Other countries have designed and operated fast reactors. S-PRISM called PRISM, is the name of a nuclear power plant design by GE Hitachi Nuclear Energy based on the Integral Fast Reactor; the IFR is fueled by an alloy of uranium and plutonium.
The fuel is contained in steel cladding with liquid sodium filling in the space between the fuel and the cladding. A void above the fuel allows helium and radioactive xenon to be collected safely without increasing pressure inside the fuel element, allows the fuel to expand without breaching the cladding, making metal rather than oxide fuel practical; the advantage of lead as opposed to sodium is that it is not reactive chemically with water or air. The disadvantages are that liquid lead is far more viscous than liquid sodium, there are numerous radioactive neutron activation products, while there are none from sodium. Metal fuel with a sodium-filled void inside the cladding to allow fuel expansion has been demonstrated in EBR-II. Metallic fuel makes pyroprocessing the reprocessing technology of choice. Fabrication of metallic fuel is easier and cheaper than ceramic fuel under remote handling conditions. Metallic fuel has better heat conductivity and lower heat capacity than oxide, which has safety advantages.
Use of liquid metal coolant removes the need for a pressure vessel around the reactor. Sodium has excellent nuclear characteristics, a high heat capacity and heat transfer capacity, low viscosity, a reasonably low melting point and a high boiling point, excellent compatibility with other materials including structural materials and fuel; the high heat capacity of the coolant and the elimination of water from the core increase the inherent safety of the core. Containing all of the primary coolant in a pool produces several safety and reliability advantages. Reprocessing is essential to achieve most of the benefits of a fast reactor, improving fuel usage and reducing radioactive waste each by several orders of magnitude. Onsite processing is; this and the use of pyroprocessing both reduce proliferation risk. Pyroprocessing has been demonstrated at EBR-II as practical on the scale required. Compared to the PUREX aqueous process, it is economical in capital cost, is unsuitable for production of weapons material, again unlike PUREX, developed for weapons programs.
Pyroprocessing makes metallic fuel the fuel of choice. The two decisions are complementary; the four basic decisions of metallic fuel, sodium coolant, pool design, onsite reprocessing by electrorefining, are complementary, produce a fuel cycle, proliferation resistant and efficient in fuel usage, a reactor with a high level of inherent safety, while minimizing the production of high-level waste. The practicality of these decisions has been demonstrated over many years of operation of EBR-II. Breeder reactors could in principle extract all of the energy contained in uranium or thorium, decreasing fuel requirements by nearly two orders of magnitude compared to traditional once-through reactors, which extract less than 0.65% of the energy in mined uranium, less than 5% of the enriched uranium with which they are fueled. This could dampen concern about fuel supply or energy used in mining. Fast reactors can "burn" long lasting nuclear transuranic waste waste components, turning liabilities into assets.
Another major waste component, fission products, would stabilize at a lower level of radioactivity than the original natural uranium ore it was attained from in two to four centuries, rather than tens of thousands of years. The fact that 4th generation reactors are being designed to use the waste from 3rd generation plants could change the nuclear story fundamentally—potentially making the combination of 3rd and 4th generation plants a more attractive energy option than 3rd generation by itself would have been, both from the perspective of waste management and energy security; the use of a medium-scale reprocessing facility onsite, the use of pyroprocessing rather than aqueous reprocessing, is claimed to reduce the proliferation potential of possible diversion of fissile material as the processing facility is in-situ/integral. In traditional light water reactors the core must be maintained at a high pressure to keep the water liquid at high temperatures. In contrast, since the IFR is a liquid metal cooled reactor, the core could operate at close to ambient pressure reducing the danger of a loss-of-coolant accident.
The entire reactor core, heat exchangers and primary cooling pumps are immersed in a pool of liquid sodium or lead, making a loss of primary coolant unlikely. T