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73-601: The passive nuclear safety systems in an ESBWR operate without using any pumps, which creates increased design safety, integrity, and reliability, while simultaneously reducing overall reactor cost. It also uses natural circulation to drive coolant flow within the reactor pressure vessel (RPV); this results in fewer systems to maintain, and precludes significant BWR casualties such as recirculation line breaks. There are no circulation pumps or associated piping, power supplies, heat exchangers, instrumentation, or controls needed for these systems. ESBWR's passive safety systems include

146-401: A PWR and uses a moving working fluid when fulfilling its mission. In category C (3+4) is the accumulator, which does not need signal input of 'intelligence' or external power. Once the pressure in the primary circuit drops below the set point of the spring-loaded accumulator valves, the valves open and water is injected into the primary circuit by compressed nitrogen. In category D (4 only) is

219-424: A fast breeder reactor is immersed into a pool of liquid metal . If the reactor overheats, thermal expansion of the metallic fuel and cladding causes more neutrons to escape the core, and the nuclear chain reaction can no longer be sustained. The large mass of liquid metal also acts as a heatsink capable of absorbing the decay heat from the core, even if the normal cooling systems would fail. The pebble bed reactor

292-414: A neutron reflector . It was designed with an Emergency Core Cooling System (ECCS) that depended on either grid power or the backup Diesel generator to be operating. The ECCS safety component was decidedly not passive. The design featured a partial containment consisting of a concrete slab above and below the reactor – with pipes and rods penetrating, an inert gas filled metal vessel to keep oxygen away from

365-440: A passive safety component that could – if so designed – render in a reactor a negative void coefficient of reactivity, regardless of the operational property of the reactor in which it is fitted. The feature would only work if it responded faster than an emerging (steam) void and the reactor components could sustain the increased coolant pressure. A reactor fitted with both safety features – if designed to constructively interact –

438-942: A 1/2 scale air-cooled RCCS) and the University of Wisconsin (home to separate 1/4 scale air and water-cooled RCCS). Entergy Entergy Corporation is a Fortune 500 integrated energy company engaged primarily in electric power production and retail distribution operations in the Deep South of the United States . Entergy is headquartered in New Orleans, Louisiana , and generates and distributes electric power to 3 million customers in Arkansas , Louisiana , Mississippi and Texas . Entergy has annual revenues of $ 11 billion and employs more than 13,000 people. Entergy traces its history to November 13, 1913, with

511-497: A 114,000-square-mile (300,000 km ) area. Entergy is the only U.S. utility to make the Dow Jones Sustainability Index (DJSI) nine years in a row. The DJSI is a listing of the companies whose overall environmental, social and economic sustainability performance scores were in the top 10 percent for their sector. Entergy was named in 2008 to Forbes list of America's Most Trustworthy Companies ,

584-712: A combination of three systems that allow for the efficient transfer of decay heat (created from nuclear decay) from the reactor to pools of water outside containment – the Isolation Condenser System, the Gravity Driven Cooling System, and the Passive Containment Cooling System . These systems utilize natural circulation based on simple laws of physics to transfer the decay heat outside containment while maintaining water levels inside

657-566: A fully passive and inherently safe decay heat removal system, termed the Reactor Cavity Cooling System (RCCS). In this design, an array of steel ducts line the concrete containment (and hence surround the reactor pressure vessel ) which provide a flow path for air driven natural circulation from chimneys positioned above grade. Derivatives of this RCCS concept (with either air or water as the working fluid) has also been featured in other gas-cooled reactor designs, including

730-412: A level above the top of the nuclear fuel. After the reactor has been depressurized, the decay heat is transferred to the containment as water inside the reactor boils and exits the reactor pressure vessel into the containment in the form of steam. The PCCS consists of a set of heat exchangers located in the upper portion of the reactor building. The steam from the reactor rises through the containment to

803-399: A limited extent, rather, relying on active safety systems such as diesel-powered motors. Some newer reactor designs feature more passive systems; the motivation being that they are highly reliable and reduce the cost associated with the installation and maintenance of systems that would otherwise require multiple trains of equipment and redundant safety class power supplies in order to achieve

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876-405: A partial meltdown. Third generation designs improve on early designs by incorporating passive or inherent safety features which require no active controls or (human) operational intervention to avoid accidents in the event of malfunction, and may rely on pressure differentials, gravity, natural convection, or the natural response of materials to high temperatures. In some designs the core of

949-512: A passive safety component. Low power swimming pool reactors such as the SLOWPOKE and TRIGA have been licensed for unattended operation in research environments because as the temperature of the low-enriched (19.75% U-235) uranium alloy hydride fuel rises, the molecular bound hydrogen in the fuel cause the heat to be transferred to the fission neutrons as they are ejected. This Doppler shifting or spectrum hardening dissipates heat from

1022-615: A ranking based on corporate governance practices and accounting transparency. On February 24, 2010, the Vermont Senate voted to prevent the Vermont Public Service Board from issuing the necessary certificate that would allow for the Vermont Yankee plant to have its license renewed for another 20 years. The vote will not affect current operation of the plant, and the issue could be revisited by

1095-657: A total of six nuclear units , and provided support services to one: The company's nuclear division is headquartered in Jackson, Mississippi . Entergy operates more than 40 plants using natural gas , nuclear , coal , oil and hydroelectric power with approximately 30,000 megawatts of electric generating capacity to serve its 2.9 million customers in the Gulf South . Its extensive transmission system carries approximately 30,000 megawatts of power across more than 15,700 miles (25,300 km) of interconnected lines within

1168-407: Is a design approach for safety features, implemented in a nuclear reactor , that does not require any active intervention on the part of the operator or electrical/electronic feedback in order to bring the reactor to a safe shutdown state, in the event of a particular type of emergency (usually overheating resulting from a loss of coolant or loss of coolant flow). Such design features tend to rely on

1241-598: Is a passively safe system and has been properly actuated, it may not fulfil its mission. Nuclear engineers have taken this into consideration: Typically only a part of the rods dropped are necessary to shut down the reactor. Samples of safety systems with passive safety components can be found in almost all nuclear power stations: the containment, hydro-accumulators in PWRs or pressure suppression systems in BWRs . In most texts on 'passively safe' components in next generation reactors,

1314-650: Is an example of a safety interlock . Rarer operational failure modes could render both such safety features useless and detract from the overall relative safety of the reactor. Traditional reactor safety systems are active in the sense that they involve electrical or mechanical operation on command systems (e.g., high-pressure water pumps). But some engineered reactor systems operate entirely passively, e.g., using pressure relief valves to manage overpressure. Parallel redundant systems are still required. Combined inherent and passive safety depends only on physical phenomena such as pressure differentials, convection, gravity or

1387-459: Is an example of a reactor exhibiting an inherently safe process that is also capable of providing a passive safety component for all operational modes. As the temperature of the fuel rises, Doppler broadening increases the probability that neutrons are captured by U-238 atoms. This reduces the chance that the neutrons are captured by U-235 atoms and initiate fission, thus reducing the reactor's power output and placing an inherent upper limit on

1460-424: Is located outside of the containment. The combination of these features allows the pool to be refilled easily with low pressure water sources and installed piping. The reactor core is shorter than in conventional BWR plants to reduce the pressure drop over the fuel, thereby enabling natural circulation. There are 1,132 fuel rod bundles and the thermal power is 4,500 MWth in the standardized SBWR. The nominal output

1533-470: Is rated at 1594 MWe gross and 1535 MWe net, yielding an overall plant Carnot efficiency of approximately 35%. In case of an accident, the ESBWR can remain in a safe, stable state for 72 hours without any operator action or even electrical power. ESBWR safety systems are designed to operate normally in the event of station blackout, which prevented proper functioning of the emergency core cooling systems at

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1606-400: Is the fuel cladding, the protective and nonreactive outer layer of the fuel pellet, which uses none of the above features: It is always closed and keeps the fuel and the fission products inside and is not open before arriving at the reprocessing plant. In category B (2+3+4) is the surge line, which connects the hot leg with the pressurizer and helps to control the pressure in the primary loop of

1679-611: Is the second-largest nuclear generator in the United States after Exelon Corporation . It had annual revenues of more than $ 11 billion in 2010 and approximately 15,000 employees. Entergy's main operating segments consist of the U.S. utility segment and the non-utility nuclear segment. The U.S. utility segment provides retail electricity services to approximately 2.9 million customers in Arkansas, Louisiana, Mississippi, and Texas. The non-utility nuclear segment owns and operates

1752-467: The Electric Bond and Share Company (EBASCO, a subsidiary of General Electric ) under Sidney Z. Mitchell merged several competing streetcar and electric utilities into New Orleans Public Service . Mitchell began turning his attention to other territories, and eventually began competing with Couch. The two men ultimately decided to merge their resources. In 1925, Electric Power and Light Corporation

1825-570: The Fukushima Daiichi Nuclear Power Plant . Below the vessel, there is a piping structure (core catcher) that allows for cooling of the core during any very severe accident. These pipes facilitate cooling above and below the molten core with water. The final safety evaluation report accepted by the NRC reports an overall core damage frequency of 1.65 * 10 per year (i.e., roughly once every 60 million years). Similarly to

1898-501: The SCRAM which utilizes moving working fluids, moving mechanical parts and signal inputs of 'intelligence' but not external power or forces: the control rods drop driven by gravity once they have been released from their magnetic clamp. But nuclear safety engineering is never that simple: Once released the rod may not fulfil its mission: It may get stuck due to earthquake conditions or due to deformed core structures. This shows that though it

1971-502: The natural response of materials to high temperatures to slow or shut down the reaction, not on the functioning of engineered components such as high-pressure water pumps. Current pressurized water reactors and boiling water reactors are systems that have been designed with one kind of passive safety feature. In the event of an excessive-power condition, as the water in the nuclear reactor core boils, pockets of steam are formed. These steam voids moderate fewer neutrons , causing

2044-496: The ABWR, The containment is inerted with nitrogen before operation to prevent fires, and can be deinerted after reactor shutdown for maintenance. As this BWR can not be controlled using flow rate control as it lacks recirculation pumps, it can instead be controlled with the temperature of the feedwater entering the reactor. The ESBWR received a positive Safety Evaluation Report and Final Design Approval on March 9, 2011. On June 7, 2011,

2117-593: The Entergy network; until 2012, it was based on where the former Gulf States Utilities was in Beaumont. Entergy Texas has since moved its operations to The Woodlands. In May of 2018, Entergy New Orleans was embroiled in a scandal surrounding its controversial proposal for a natural gas power plant in East New Orleans. An Entergy subcontractor used Crowds on Demand to artificially lobby council support for

2190-481: The FLiBe temperature increased, it expanded, along with the uranium ions it carried; this decreased density resulted in a reduction of fissile material in the core, which decreased the rate of fission. With less heat input, the net result was that the reactor would cool. Extending from the bottom of the reactor core was a pipe that lead to passively cooled drain tanks. The pipe had a "freeze valve" along its length, in which

2263-843: The Japanese High-temperature engineering test reactor , the Chinese HTR-10 , the South African PBMR , and the Russian GT-MHR . While none of these designs have been commercialized for power generation research in these areas is active, specifically in support of the Generation IV initiative and NGNP programs, with experimental facilities at Argonne National Laboratory (home to the Natural convection Shutdown heat removal Test Facility,

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2336-481: The NRC completed its public comment period. Final rule was issued on September 16, 2014, after two outstanding problems with GE-Hitachi's modeling of loads on the steam dryer were solved. In January 2014, GE Hitachi paid $ 2.7 million to resolve a lawsuit alleging it made false claims to the NRC about its analysis of the steam dryer. The NRC granted design approval in September 2014. However, in September 2015, at

2409-553: The PCCS heat exchangers where the steam is condensed. The condensate then drains from the PCCS heat exchangers back to the GDCS pools where it completes the cycle and drains back to the reactor pressure vessel. Both the ICS and PCCS heat exchangers are submerged in a pool of water large enough to provide 72 hours of reactor decay heat removal capability. The pool is vented to the atmosphere and

2482-474: The active cooling system. In other words, whilst the inherently safe heat transfer process provides a passive safety component preventing excessive heat while the reactor is operating, the same inherently safe heat transfer process does not provide a passive safety component if the reactor is shut down (SCRAMed). The Three Mile Island accident exposed this design deficiency: the reactor and steam generator were shut down but with loss of coolant it still suffered

2555-416: The addition of a neutron reflector such as pyrolytic graphite . The higher density of the fuel along with additional lower density FLiBe fluoride coolant without fuel provides a flotation layer passive safety component in which lower density graphite that breaks off control rods or an immersion matrix during mechanical failure does not induce criticality. Gravity driven drainage of reactor liquids provides

2628-558: The city of New Orleans in August 2005, Entergy temporarily relocated the 1,500 employees and contractors who worked at the headquarters to other cities, including Clinton, Mississippi , Little Rock, Arkansas , and The Woodlands, Texas . In April 2006, the company began moving back into its New Orleans headquarters. In 2011, Entergy and Coulomb Technologies , an electric vehicle charging station maker, began to donate free electric vehicle charging stations at 16 sites at college campuses in

2701-482: The containment dome. The integral fast reactor was a fast breeder reactor run by the Argonne National Laboratory . It was a sodium cooled reactor capable of withstanding a loss of (coolant) flow without SCRAM and loss of heatsink without SCRAM . This was demonstrated throughout a series of safety tests in which the reactor successfully shut down without operator intervention. The project

2774-463: The containment into a neighbouring building. The pilot-operated relief valve at TMI-2 was designed to shut automatically after relieving excessive pressure inside the reactor into a quench tank. However the valve mechanically failed causing the PORV quench tank to fill, and the relief diaphragm to eventually rupture into the containment building. The containment building sump pumps automatically pumped

2847-427: The contaminated water outside the containment building. Both a working PORV with quench tank and separately the containment building with sump provided two layers of passive safety. An unreliable PORV negated its designed passive safety. The plant design featured only a single open/close indicator based on the status of its solenoid actuator, instead of a separate indicator of the PORV's actual position. This rendered

2920-596: The control of a new holding company, Middle South Utilities. It changed its name to Entergy in 1989, and merged/bought Gulf States Utilities, based in Beaumont, Texas , as of 12:00 midnight, January 1, 1994. In the late 1990s, Entergy pursued a strategy of global expansion into unregulated markets, acquiring substantial facilities in Australia, Argentina, and the United Kingdom. Shareholder dissatisfaction with

2993-431: The control systems are used to operate the plant under normal conditions. Sometimes a system combines both features. Passive safety refers to safety system components, whereas inherent safety refers to control system process regardless of the presence or absence of safety-specific subsystems. An example of a safety system with passive safety components is the containment vessel of a nuclear reactor. The concrete walls and

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3066-492: The core fuel elements facilitating total surveillance and providing nuclear non-proliferation safety. Both the fuel molecules themselves and the open expanse of the pool are passive safety components. Quality implementations of these designs are arguably the safest nuclear reactors. Three Mile Island Unit 2 was unable to contain about 480 PBq of radioactive noble gases from release into the environment and around 120 kL of radioactive contaminated cooling water from release beyond

3139-399: The degree that the control systems were reliable, this design did have a corresponding degree of active inherent safety. The reactor was unsafe at low power levels because erroneous control rod movement would have a counter-intuitively magnified effect. Chernobyl Reactor 4 was built instead with manual crane driven boron control rods that were tipped with the moderator substance, graphite,

3212-431: The engineering of components such that their predicted behaviour would slow down, rather than accelerate the deterioration of the reactor state; they typically take advantage of natural forces or phenomena such as gravity, buoyancy, pressure differences, conduction or natural heat convection to accomplish safety functions without requiring an active power source. Many older common reactor designs use passive safety systems to

3285-484: The event of coolant loss , no operator action is required for three days. The Westinghouse AP1000 ("AP" standing for "Advanced Passive") uses passive safety components. In the event of an accident, no operator action is required for 72 hours. Recent versions of the Russian VVER have added a passive heat removal system to the existing active systems, utilising a cooling system and water tanks built on top of

3358-545: The formation of Arkansas Power Company. Founder Harvey C. Couch used sawdust from a lumber company to bring electricity to rural Arkansas. In the 1920s, Couch set his sights on buying electric companies in other states. In 1923, he merged four independent companies in Mississippi into Mississippi Power and Light. Two years later, he formed Louisiana Power and Light to provide power to his Mississippi customers from northern Louisiana's natural gas fields. Meanwhile, in 1922,

3431-406: The fuel itself is also chemically corrosion resistant ensuring a sustainable safety performance of the fuel molecules throughout their lifetime. A large expanse of water and the concrete surround provided by the pool for high energy neutrons to penetrate ensures the process has a high degree of intrinsic safety. The core is visible through the pool and verification measurements can be made directly on

3504-410: The fuel more rapidly throughout the pool the higher the fuel temperature increases ensuring rapid cooling of fuel whilst maintaining a much lower water temperature than the fuel. Prompt, self-dispersing, high efficiency hydrogen-neutron heat transfer rather than inefficient radionuclide -water heat transfer ensures the fuel cannot melt through accident alone. In uranium-zirconium alloy hydride variants,

3577-407: The increased safety associated with greater coverage by passive systems, all current large-scale nuclear reactors require both external (active) and internal (passive) systems. There are no 'passively safe' reactors, only systems and components. Safety systems are used to maintain control of the plant if it goes outside normal conditions in case of anticipated operational occurrences or accidents, while

3650-512: The key issue is that no pumps are needed to fulfil the mission of a safety system and that all active components (generally I&C and valves) of the systems work with the electric power from batteries. IAEA explicitly uses the following caveat: ... passivity is not synonymous with reliability or availability, even less with assured adequacy of the safety feature, though several factors potentially adverse to performance can be more easily counteracted through passive design (public perception). On

3723-550: The legislature in either a special session later in 2010 or in its next regular session in 2011. Entergy Texas operates as a wholly owned subsidiary. This was done to prepare the Texas side for de-regulation under Texas law, but Entergy later notified the Public Utility Commission of Texas that it would not split off the Texas side as a de-regulated operation. Because of this, the Texas side remains connected to

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3796-400: The loss of water inventory, the reactor is depressurized and the GDCS is initiated. It consists of large pools of water inside containment located above the reactor that are connected to the reactor pressure vessel. When the GDCS system is initiated, gravity forces water to flow from the pools into the reactor. The pools are sized to provide sufficient amounts of water to maintain the water at

3869-480: The mechanical reliability of the PORV indeterminate directly, and therefore its passive safety status indeterminate. The automatic sump pumps and/or insufficient containment sump capacity negated the containment building designed passive safety. The notorious RBMK graphite moderated, water-cooled reactors of Chernobyl Power Plant disaster were designed with a positive void coefficient with boron control rods on electromagnetic grapples for reaction speed control. To

3942-421: The metal vessel could contain a steam, graphite and oxygen driven hydrogen explosion. The water boxes could not sustain high pressure failure of the pipes. The passive safety components as designed were inadequate to fulfill the safety requirements of the system. The General Electric Company ESBWR (Economic Simplified Boiling Water Reactor, a BWR ) is a design reported to use passive safety components. In

4015-405: The molten salt was actively cooled to a solid plug by a fan blowing air over the pipe. If the reactor vessel developed excessive heat or lost electric power to the air cooling, the plug would melt; the FLiBe would be pulled out of the reactor core by gravity into dump tanks, and criticality would cease as the salt lost contact with the graphite moderator. The General Atomics HTGR design features

4088-514: The operational property of a negative void coefficient of reactivity are said to possess an inherent safety process feature. An operational failure mode could potentially alter the process to render such a reactor unsafe. Reactors could be fitted with a hydraulic safety system component that increases the inflow pressure of coolant (esp. water) in response to increased outflow pressure of the moderator and coolant without control system intervention. Such reactors would be described as fitted with such

4161-479: The other hand active designs employing variable controls permit much more precise accomplishment of safety functions; this may be particularly desirable under accident management conditions. Nuclear reactor response properties such as Temperature coefficient of reactivity and Void coefficient of reactivity usually refer to the thermodynamic and phase-change response of the neutron moderator heat transfer process respectively. Reactors whose heat transfer process has

4234-580: The power level inside the reactor to lower. The BORAX experiments and the SL-1 meltdown accident proved this principle. A reactor design whose inherently safe process directly provides a passive safety component during a specific failure condition in all operational modes is typically described as relatively fail-safe to that failure condition. However most current water-cooled and -moderated reactors, when scrammed , can not remove residual production and decay heat without either process heat transfer or

4307-420: The reactor building. Steam leaves the reactor through the ICS piping and travels to the ICS heat exchangers which are submerged in a large pool. The steam is condensed in the heat exchangers and the denser condensate then flows back down to the reactor to complete the cooling loop. Reactor coolant is cycled through this flow path to provide continuous cooling and to add water to the reactor core. In cases where

4380-424: The reactor coolant pressure boundary does not remain intact and water inventory in the core is being lost, the Passive Containment Cooling System (PCCS) and Gravity Driven Cooling System (GDCS) work in concert to maintain the water level in the core and remove decay heat from the reactor by transferring it outside containment. If the water level inside the reactor pressure vessel drops to a predetermined level, due to

4453-487: The reactor, keeping the nuclear fuel submerged in water and adequately cooled. In events where the reactor coolant pressure boundary remains intact, the Isolation Condenser System (ICS) is used to remove decay heat from the reactor and transfer it outside containment. The ICS system is a closed loop system that connects the reactor pressure vessel to a heat exchanger located in the upper elevation of

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4526-499: The remainder of the transmission organization , which reduces flow of cheaper electricity into the area. With a integrated power utility business model, Entergy makes money by constructing power plants, reducing the company's incentive to build transmission connecting it to other regions. Experts state these capacity contraints result in higher profits for the company at the expense of customers and lower reliability, such as rolling blackouts during Winter Storm Uri in 2021. Prior to

4599-658: The request of owner Entergy , the NRC withdrew the Combined Construction and Operating License application for the first proposed ESBWR unit at Grand Gulf Nuclear Generating Station . On May 31, 2017, the Nuclear Regulatory Commission announced that it had authorized the issuance of a Combined License for North Anna Nuclear Generating Station unit 3. The project was placed on hold later in 2017 before construction started. Passive nuclear safety Passive nuclear safety

4672-502: The results of this strategy led to a shakeup of management, culminating with the ouster of longtime CEO Ed Lupberger in 1998. Lupberger was replaced by Wayne Leonard, formerly of Cinergy , who supervised the company's disinvestment from overseas holdings. Since its inception, Entergy has been headquartered in New Orleans. That city had also been home to Entergy's various corporate predecessors since 1925. After Hurricane Katrina hit

4745-480: The same level of reliability. However, weak driving forces that power many passive safety features can pose significant challenges to effectiveness of a passive system, particularly in the short term following an accident. 'Passive safety' describes any safety mechanism whose engagement requires little or no outside power or human control. Modern reactor designs have focused on increasing the number of passive systems to mitigate risk of compounding human error. Despite

4818-567: The southeast corner of Louisiana and the cities of Lafayette and Baton Rouge, the eastern three-fourths of Arkansas and the western half of Mississippi . It also includes part of southeastern Texas , including the Beaumont-Port Arthur-Orange and Conroe-Woodlands-Kingwood areas. A member of the Fortune 500 , Entergy owns and operates power plants with approximately 30,000 megawatts of electric generating capacity, and it

4891-676: The southern U.S. Its first installation was at Louisiana State University in Baton Rouge , and is free to use for faculty and students. In 2013, Entergy joined the Midcontinent Independent System Operator (MISO) as is southern region following an Department of Justice investigation into the company's anti-competitive behavior. By joining MISO rather than the Southwest Power Pool , Entergy's service areas have limited interconnection to

4964-422: The steel liner of the vessel exhibit passive safety, but require active systems (valves, feedback loops, external instrumentation, control circuits, etc.) which require external power and human operation to function. The International Atomic Energy Agency (IAEA) classifies the degree of "passive safety" of components from category A to D depending on what the system does not make use of: In category A (1+2+3+4)

5037-492: The temperature of the fuel. The geometry and design of the fuel pebbles provides an important passive safety component. Single fluid fluoride molten salt reactors feature fissile , fertile and actinide radioisotopes in molecular bonds with the fluoride coolant. The molecular bonds provide a passive safety feature in that a loss-of-coolant event corresponds with a loss-of-fuel event. The molten fluoride fuel can not itself reach criticality but only reaches criticality by

5110-486: The use of the current Entergy logo, each subsidiary had its own distinctive logo. Upon the renaming of the company from Middle South Utilities System to Entergy, the present logo was adopted. Louisiana Power and Light Company, for example (today's Entergy Louisiana) used the logo shown at right extensively from about 1967 to 1989, on buildings equipment, and advertising. Each of Middle South Utilities' subsidiaries used similar-styled logos Entergy's service territory includes

5183-543: The water-cooled hot graphite, a fire-proof roof, and the pipes below the vessel sealed in secondary water filled boxes. The roof, metal vessel, concrete slabs and water boxes are examples of passive safety components. The roof in the Chernobyl Power Plant complex was made of bitumen – against design – rendering it ignitable. Unlike the Three Mile Island accident , neither the concrete slabs nor

5256-494: Was canceled due to proliferation concerns before it could be copied elsewhere. The Molten-Salt Reactor Experiment (MSRE) was a molten salt reactor run by the Oak Ridge National Laboratory . It was nuclear graphite moderated and the coolant salt used was FLiBe , which also carried the uranium-233 fluoride fuel dissolved in it. The MSRE had a negative temperature coefficient of reactivity: as

5329-703: Was formed, an EBASCO subsidiary headquartered in New Orleans, with Couch as its president. It was the parent company for Mississippi Power and Light, Louisiana Power and Light, New Orleans Public Service, and Arkansas Power and Light. EBASCO fought the constitutionality of the Public Utility Holding Company Act of 1935 , losing a Supreme Court case in 1938 , and was ordered dissolved under the provisions of that act in 1949. Mississippi Power and Light, Louisiana Power and Light, New Orleans Public Service and Arkansas Power and Light were deemed to be an integrated system, and were reorganized under

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