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35-400: EM2 is an advanced modular reactor expected to produce 265 MW e (500 MW th ) of power with evaporative cooling (240 MW e with dry cooling) at a core outlet temperature of 850 °C (1,600 °F). The reactor will be fully enclosed in an underground containment structure for 30 years without requiring refueling. EM2 differs from current reactors in that it does not use water coolant but

70-438: A GFR reactor design, the unit operates on fast neutrons; no moderator is needed to slow neutrons down. This means that, apart from nuclear fuel such as uranium, other fuels can be used. The most common is thorium, which absorbs a fast neutron and decays into Uranium 233. This means GFR designs have breeding properties—they can use fuel that is unsuitable in light water reactor designs and breed fuel. Because of these properties, once

105-461: A device is suitable for its application, and will withstand the environmental conditions in which it is used. Normal operating temperature ranges are affected by several factors, such as the power dissipation of the device. These factors are used to define a "threshold temperature" of a device, i.e. its maximum normal operating temperature, and a maximum operating temperature beyond which the device will no longer function. Between these two temperatures,

140-496: A large-scale deployment of the EM2 could reduce the long-term need for uranium enrichment and eliminate conventional nuclear reprocessing, which requires plutonium separation. Conventional light water reactors require refueling every 18 months. EM2's 30-year fuel cycle minimizes the need for fuel handling and reduces access to fuel material, thus reducing proliferation concerns. EM2 utilizes passive safety systems designed to safely shutdown

175-788: A material is "highly dependent on operating temperature", and creep analysis is thus an important part of design validation. Some of the effects of creep and thermal fatigue may be mitigated by integrating cooling systems into the device's design, reducing the peak temperature experienced by the metal. Commercial and retail products are manufactured to less stringent requirements than those for military and aerospace applications. For example, microprocessors produced by Intel Corporation are manufactured to three grades: commercial, industrial and extended. Because some devices generate heat during operation, they may require thermal management to ensure they are within their specified operating temperature range; specifically, that they are operating at or below

210-445: A new conversion technique in which an initial "starter" section of the core provides the neutrons to convert fertile material (used nuclear fuel, thorium, or depleted uranium ) into burnable fissile fuel. First generation EM2 units use enriched uranium starters (approximately 15 percent U235 ) to initiate the conversion process. The starter U235 is consumed as the fertile material is converted to fissile fuel. The core life expectancy

245-637: A source of cooling water. If the reactor is to become part of a hydrogen economy , the coolant outlet temperature of 850°C would allow the sulfur iodine cycle to be used which directly converts thermal energy into hydrogen (without electric or other intermediate steps) with an overall thermal efficiency around 50%. EM2 can burn used nuclear fuel , also referred to as " spent fuel " from current light water reactors . It can utilize an estimated 97% of unused fuel that current reactors leave behind as waste. Spent fuel rods from conventional nuclear reactors are put into storage and considered to be nuclear waste , by

280-407: A system fan)", though in "a properly designed system, this feature should never become active". Cooling and other thermal management techniques may affect performance and noise level. Noise mitigation strategies may be required in residential applications to ensure that the noise level does not become uncomfortable. Battery service life and efficacy is affected by operating temperature. Efficacy

315-714: Is a helium - cooled system operating with an outlet temperature of 850 °C (1,560 °F) using a direct Brayton closed-cycle gas turbine for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of fission products : composite ceramic fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks, which allows for better coolant circulation than traditional fuel assemblies. The reactors are intended for use in nuclear power plants to produce electricity, while at

350-457: Is a fast reactor, but in other ways similar to a high temperature gas-cooled reactor . It differs from the HTGR design in that the core has a higher fissile fuel content as well as a non-fissile, fertile, breeding component. There is no neutron moderator , as the chain reaction is sustained by fast neutrons. Due to the higher fissile fuel content, the design has a higher power density than the HTGR. In

385-666: Is approximately 30 years without refueling or reshuffling the fuel. Substantial amounts of usable fissile material remain in the EM2 core at the end of life. This material can be reused as the starter for the second generation of EM2s, without conventional nuclear reprocessing . There is no separation of individual heavy metals required and no additional enriched uranium needed. Only fission products would be removed, which would decay to near-background radiation levels in about 500 years compared to conventional spent fuel, which requires about 10,000 years. All EM2 heavy metal discharges could be recycled into new EM2 units, effectively closing

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420-451: Is currently being developed by Czech Republic, France, Hungary, Slovakia and Poland. The primary aim of ALLEGRO is to create a conceptual design of a helium-cooled fast reactor with passive decay heat removal during LOCA accidents based on nitrogen injections into the guard vessel containing the reactor pressure vessel and to design an air-tight guard vessel capable of withstanding the increased pressure (over 10 bar) and temperature during

455-460: Is determined by comparing the service life achieved by the battery as a percentage of its service life achieved at 20 °C (68 °F) versus temperature. Ohmic load and operating temperature often jointly determine a battery's discharge rate. Moreover, if the expected operating temperature for a primary battery deviates from the typical 10 °C to 25 °C (50 to 77 °F) range, then operating temperature "will often have an influence on

490-410: Is instead a gas-cooled fast reactor , which uses helium as a coolant for an additional level of safety. The reactor uses a composite of silicon carbide as a fuel cladding material and zirconium silicide as neutron reflector material. The reactor unit is coupled to direct-drive helium closed-cycle gas turbine which drives a generator to produce electricity. The nuclear core design is based upon

525-577: Is the low thermal inertia and poor heat removal capability at low helium pressures, although these issues are shared with thermal reactors which have been constructed. Peter Fortescue , whilst at General Atomic, was leader of the team responsible for the initial development of the High temperature gas-cooled reactor (HTGR), as well as the Gas-cooled Fast Reactor (GCFR) system. Gas-cooled projects (thermal spectrum) include decommissioned reactors such as

560-1057: The Dragon reactor , built and operated in the United Kingdom , the AVR and the THTR-300 , built and operated in Germany , and Peach Bottom and Fort St. Vrain , built and operated in the United States . Ongoing demonstrations include the High-temperature engineering test reactor in Japan , which reached full power (30 MWth) using fuel compacts inserted in prismatic blocks in 1999, and the HTR-10 in China , which reached its full capacity at 10 MWth in 2003 using pebble fuel. A 400 MWth pebble bed modular reactor demonstration plant

595-769: The United States Department of Defense has defined the United States Military Standard for all products used by the United States Armed Forces. A product's environmental design and test limits to the conditions that it will undergo throughout its service life are specified in MIL-STD-810 , the Department of Defense Test Method Standard for Environmental Engineering Considerations and Laboratory Tests . The MIL-STD-810G standard specifies that

630-416: The basal body temperature , is achieved during sleep. In women, it is affected by ovulation, causing a biphasic pattern which may be used as a component of fertility awareness . In humans, the hypothalamus regulates metabolism , and hence the basal metabolic rate . Amongst its functions is the regulation of body temperature. The core body temperature is also one of the classic phase markers for measuring

665-625: The nuclear fuel cycle , which minimizes nuclear proliferation risks and the need for long-term repositories to secure nuclear materials. EM2 power costs are expected to be lower due to high power conversion (from thermal input to electric output) efficiency, a reduced number of components, and long core life. EM2 is expected to achieve a thermal efficiency of above 50% due to its high core outlet temperature and closed Brayton power cycle. The Brayton cycle eliminates many expensive components, including steam generators , pressurizers, condensers , and feedwater pumps. The design would utilize only 1/6th of

700-487: The "operating temperature stabilization is attained when the temperature of the functioning part(s) of the test item considered to have the longest thermal lag is changing at a rate of no more than 2.0 °C (3.6 °F) per hour." It also specifies procedures to assess the performance of materials to extreme temperature loads . Military engine turbine blades experience two significant deformation stresses during normal service, creep and thermal fatigue . Creep life of

735-567: The LOCA accident. Operating temperature An operating temperature is the allowable temperature range of the local ambient environment at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the device function and application context, and ranges from the minimum operating temperature to the maximum operating temperature (or peak operating temperature ). Outside this range of safe operating temperatures

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770-479: The ambient temperature, and for integrated circuits , is given by the equation: in which T J is the junction temperature in °C, T a is the ambient temperature in °C, P D is the power dissipation of the integrated circuit in W , and R ja is the junction to ambient thermal resistance in °C/W. Electrical and mechanical devices used in military and aerospace applications may need to endure greater environmental variability, including temperature range. In

805-552: The device may fail. It is one component of reliability engineering . Similarly, biological systems have a viable temperature range, which might be referred to as an "operating temperature". Most semiconductor devices are manufactured in several temperature grades. Broadly accepted grades are: Nevertheless, each manufacturer defines its own temperature grades so designers must pay attention to datasheet specifications. For example, Maxim Integrated uses five temperature grades for its products: The use of such grades ensures that

840-411: The device will operate at a non-peak level. For instance, a resistor may have a threshold temperature of 70 °C (158 °F) and a maximum temperature of 155 °C (311 °F), between which it exhibits a thermal derating . For electrical devices, the operating temperature may be the junction temperature (T J ) of the semiconductor in the device. The junction temperature is affected by

875-514: The initial loading of fuel has been applied into the reactor, the unit can go years without needing fuel (sometimes exceeding 20 years). If these reactors are used for breeding, it is economical to remove the fuel and separate the generated fuel for future use. The gas used can be many different types, including carbon dioxide or helium. It must be composed of elements with low neutron capture cross sections to prevent positive void coefficient and induced radioactivity . The use of gas also removes

910-435: The maximum operating temperature of the device. Cooling a microprocessor mounted in a typical commercial or retail configuration requires "a heatsink properly mounted to the processor, and effective airflow through the system chassis". Systems are designed to protect the processor from unusual operating conditions, such as "higher than normal ambient air temperatures or failure of a system thermal management component (such as

945-424: The nuclear concrete of a conventional light water reactor. Each module can be manufactured in either U.S. domestic or foreign facilities using replacement parts manufacturing and supply chain management with large components shipped by commercial truck or rail to a site for final assembly, where it will be fully enclosed in an underground containment structure. Dry cooling capability allows siting in locations without

980-415: The nuclear industry and the general public. Nuclear waste from light water reactors retains more than 95% of its original energy because such reactors cannot burn fertile U238, while fast reactors can. The current U.S. inventory of spent fuel is equivalent to nine trillion barrels of oil - four times more than the known reserves. By using spent nuclear waste and depleted uranium stockpiles as its fuel source,

1015-552: The plant against terrorism and other threats. EM2's high operating temperature can provide process heat for petrochemical fuel products and alternative fuels , such as biofuels and hydrogen . Gas-cooled fast reactor The gas-cooled fast reactor ( GFR ) system is a nuclear reactor design which is currently in development. Classed as a Generation IV reactor , it features a fast-neutron spectrum and closed fuel cycle for efficient conversion of fertile uranium and management of actinides . The reference reactor design

1050-842: The possibility of phase transition –induced explosions, such as when the water in a water-cooled reactor ( PWR or BWR ) flashes to steam upon overheating or depressurization. The use of gas also allows for higher operating temperatures than are possible with other coolants, increasing thermal efficiency , and allowing other non-mechanical applications of the energy, such as the production of hydrogen fuel. Past pilot and demonstration projects have all used thermal designs with graphite moderators. As such, no true gas-cooled fast reactor design has ever been brought to criticality. The main challenges that have yet to be overcome are in-vessel structural materials, both in-core and out-of-core, that will have to withstand fast-neutron damage and high temperatures (up to 1,600 °C [2,910 °F]). Another problem

1085-595: The reactor in emergency conditions using only gravity and natural convection. Control rods are automatically inserted during a loss-of-power incident via gravity. Natural convection flow is used to cool the core during whole site loss of power incidents. No external water supply is necessary for emergency cooling. The use of silicon carbide as fuel cladding in the core ensures no hydrogen production during accident scenarios and allows an extended period of response when compared to Zircaloy metal cladding used in current reactors. Underground siting improves safety and security of

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1120-448: The same time producing (breeding) new nuclear fuel. Fast reactors were originally designed to be primarily breeder reactors . This was because of a view at the time of their conception that there was an imminent shortage of uranium fuel for existing reactors. The projected increase in uranium price did not materialize, but if uranium demand increases in the future, then there may be renewed interest in fast reactors . The GFR base design

1155-401: The timing of an individual's Circadian rhythm . Changes to the normal human body temperature may result in discomfort. The most common such change is a fever , a temporary elevation of the body's thermoregulatory set-point, typically by about 1–2 °C (1.8–3.6 °F). Hyperthermia is an acute condition caused by the body absorbing more heat than it can dissipate, whereas hypothermia

1190-406: The type of battery selected for the application". Energy reclamation from partially depleted lithium sulfur dioxide battery has been shown to improve when "appropriately increasing the battery operating temperature". Mammals attempt to maintain a comfortable body temperature under various conditions by thermoregulation , part of mammalian homeostasis . The lowest normal temperature of a mammal,

1225-573: Was designed by PBMR Pty for deployment in South Africa but withdrawn in 2010, and a consortium of Russian institutes is designing a 600 MWth GT-MHR (prismatic block reactor) in cooperation with General Atomics . In 2010, General Atomics announced the Energy Multiplier Module reactor design, an advanced version of the GT-MHR . A European gas cooled fast reactor (GFR) demonstrator, ALLEGRO,

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