Fast reactors typically use boron carbide control rods. It eliminates the need and associated expense of extra components and redundant safety systems required by other technologies for protection against coolant leakages.
Both coolants can be used at or near atmospheric pressure, which simplifies engineering and reduces cost. Their high-temperature operation benefits thermodynamic efficiency. Three versions will be pitched to heating, cogeneration and the chemical industry. Also the lead version of the Moltex stable salt reactor is fast. These are described in the Molten salt reactors section below. Small FNRs are designed to be factory-built and shipped to site on truck, train or barge and then shipped back again or to a regional fuel cycle centre at end of life.
They would mostly be installed below ground level and with high surface area to volume ratio they have good passive cooling potential. Disposal is envisaged as entire units, without separate spent fuel storage, or after fuel removed for reprocessing.
See also Fast Neutron Reactors paper. Several US companies are developing sodium-cooled fast reactor designs based on the It used the pyrometallurgically-refined used fuel from light water reactors as fuel, including a wide range of actinides.
After operating from to it is now decommissioned. An intermediate sodium loop takes heat to steam generators. All transuranic elements are removed together in the electrometallurgical reprocessing so that fresh fuel has minor actinides with the plutonium and uranium.
The reactor is designed to use a heterogeneous metal alloy core with fuel assemblies in two fuel zones. Breeding ratio depends on purpose and hence configuration, so ranges from 0. The commercial-scale plant concept, part of an 'Advanced Recycling Center', would use three power blocks six reactor modules to provide MWe.
In GE Hitachi announced that it was shifting its marketing strategy to pitch the reactor directly to utilities as a way to recycle excess plutonium while producing electricity for the grid.
GEH bills it as a simplified design with passive safety features and using modular construction techniques. Its reference construction schedule is 36 months. The whole stockpile could be irradiated thus in five years, with some by-product electricity but frequent interruptions for fuel changing and the plant would then proceed to re-use it for about 55 years solely for MWe of electricity generation, with one-third of the fuel being changed every two years.
For this UK version, the breeding ratio is 0. No reprocessing plant 'Advanced Recycling Center' is envisaged initially, but this could be added later. The programme aims to provide the capability for testing advanced nuclear fuels, materials, instrumentation, and sensors. The VTR, which is intended to be operational at INL by the end of , would be an adapted PRISM reactor to provide accelerated neutron damage rates 20 times greater than current water-cooled test reactors.
They would be supported by the Energy Northwest utility consortium. This is based on a PRISM reactor of MWe and uses molten salt to store heat so that the output could be increased to about MWe for up to five hours for load-following. In October Bechtel joined the consortium to provide design, licensing, procurement and construction services to the project. In June TerraPower announced plans to build a demonstration Natrium unit in Wyoming at a retired coal plant site. It plans to submit a construction permit application in and an operating licence application in See also Electrometallurgical 'pyroprocessing' section in the information page on Processing of Used Nuclear Fuel.
It will be factory-produced, with components readily assembled onsite, and with 'walk-away' passive safety. Installation would be below ground level.
The ARC system comprises a uranium alloy metal core cartridge submerged in sodium at ambient pressure in a stainless steel tank. It would have a refuelling interval of 20 years for cartridge changeover, with Initial fuel will be low-enriched uranium Reprocessing its used fuel will not separate plutonium. ARC has load-following capability. The reactivity control system is passive, using lithium expansion modules LEMs which give burn-up compensation, partial load operation as well as negative reactivity feedback.
During normal operation, lithium-6 in the LEM is suspended on an inert gas above the core region. Other kinds of lithium modules, also integrated into the fuel cartridge, shut down and start up the reactor. Cooling is by molten sodium, and with the LEM control system, reactor power is proportional to primary coolant flow rate.
Refuelling would be every 10 years in an inert gas environment. Operation would require no skill, due to the inherent safety design features. The whole plant would be about 6. It uses sodium as coolant with electromagnetic pumps and has passive safety features, notably negative temperature coefficient of reactivity.
The whole unit would be factory-built, transported to site, installed below ground level, and would drive a steam cycle via a secondary sodium loop. It is capable of three decades of continuous operation without refuelling.
Steady power output over the core lifetime in 30 MWt version is achieved by progressively moving upwards an annular reflector around the slender core 0. After 14 years a neutron absorber at the centre of the core is removed and the reflector repeats its slow movement up the core for 16 more years. In the event of power loss the reflector falls to the bottom of the reactor vessel, slowing the reaction, and external air circulation gives decay heat removal.
A further safety device is a neutron absorber rod which can drop into the core. After 30 years the fuel would be allowed to cool for a year, then it would be removed and shipped for storage or disposal.
The design has gained considerable support in Alaska and toward the end of the town of Galena granted initial approval for Toshiba to build a 10 MWe 30 MWt 4S reactor in that remote location. A pre-application Nuclear Regulatory Commission NRC review was under way to with a view to application for design certification in October , and combined construction and operating licence COL application to follow.
Toshiba planned a worldwide marketing program to sell the units for power generation at remote mines, for extraction of tar sands, desalination plants and for making hydrogen. Eventually it expected sales for hydrogen production to outnumber those for power supply. This is not a small reactor, and details are in the information page on Fast Neutron Reactors and at TerraPower. Lead or lead-bismuth eutectic in fast neutron reactors are capable of high temperature operation at atmospheric pressure.
This means that efficiency is better due to greater spacing between fuel pins which then allows coolant flow by convection for decay heat removal. Also since they do not react with water the heat exchanger interface is safer. They do not burn when exposed to air.
Lead and Pb-Bi have much higher thermal conductivity than water, but lower than sodium. While lead has limited activation from neutrons, a problem with Pb-Bi is that it yields toxic polonium Po activation product, an alpha-emitter with a half-life of days.
In Russia declassified a lot of research information derived from its experience with Pb-Bi in submarine reactors, and US interest in using Pb generally or Pb-Bi for small reactors has increased subsequently. Russia has experimented with several lead-cooled reactor designs, and gained 70 reactor-years experience with lead-bismuth cooling to s in submarine reactors. The core sits in a pool of lead at near atmospheric pressure. Effective enrichment is about Fuel cycle is quoted at years with partial refuelling at about 10 months.
No weapons-grade plutonium can be produced since there is no uranium blanket , and used fuel can be recycled indefinitely, with on-site facilities. The pilot demonstration unit is being built at Seversk for completion in , and MWe units are planned.
The combination enables a fully closed fuel cycle on one site. It is designed to be able to use a wide variety of fuels, though the pilot unit would initially use uranium oxide enriched to Refuelling interval would be years and year operating lifetime was envisaged. The melting point of the Pb-Bi coolant is A power station with such modules was expected to supply electricity at lower cost than any other new technology with an equal capacity as well as achieving inherent safety and high proliferation resistance.
Russia built seven Alfa-class submarines, each powered by a compact MWt Pb-Bi cooled reactor, and 80 reactor-years' operational experience was acquired with these.
In October Rosatom reported: "Experts have confirmed there are no scientific or technical issues that would prevent completion of the project and obtaining a construction licence. It was to contribute most of the capital, and Rosatom is now looking for another investor. The SVBR would have been the first reactor cooled by heavy metal to generate electricity. It is described by Gidropress as a multi-function reactor for power, heat or desalination.
An SVBR was also envisaged, with the same design principles, a year refuelling interval and generating capacity of 12 MWe, and it too is a multi-purpose unit. Link to SVBR brochure. The reactor was originally conceived as a potassium-cooled self-regulating 'nuclear battery' fuelled by uranium hydride m. However, in , Hyperion Power changed the design to uranium nitride fuel and lead-bismuth cooling to expedite design certification This now classes it as a fast neutron reactor, without moderation.
The company claims that the ceramic nitride fuel has superior thermal and neutronic properties compared with uranium oxide.
Enrichment is The unit would be installed below ground level. The reactor vessel housing the core and primary heat transfer circuit is about 1.
It is easily portable, sealed and has no moving parts. A secondary cooling circuit transfers heat to an external steam generator. The reactor module is designed to operate for electricity or process heat or cogeneration continuously for up to 10 years without refuelling. Another reactor module could then take its place in the overall plant.
In March , Hyperion as the company then was notified the US Nuclear Regulatory Commission that it planned to submit a design certification application in The company said then that it has many expressions of interest for ordering units. In September , the company signed an agreement with Savannah River Nuclear Solutions to possibly build a demonstration unit at the Department of Energy site there. Hyperion planned to build a prototype by , possibly with uranium oxide fuel if the nitride were not then available.
In two papers on nuclear marine propulsion were published arising from a major international industry project led by Lloyd's Register. They describe a preliminary concept design study for a , dwt Suezmax tanker that is based on a conventional hull form with a 70 MW Gen4 Energy power module for propulsion. It pitched its design for remote sites having smaller power requirements.
The Westinghouse Lead-cooled Fast Reactor LFR programme originated from an investigation performed in aimed at identifying the technology that would best support addressing the challenges of nuclear power, for global deployment. It is at the conceptual design stage for up to MWe as a modular pool-type unit, simple, scalable and with passive safety. It will have flexible output to complement intermittent renewable feed to the grid.
Westinghouse expects it to be very competitive, having low capital and construction costs with enhanced safety. Because lead coolant operates at atmospheric pressure and does not exothermically react with air or with power conversion fluids such as supercritical carbon dioxide and water , LFR technology also eliminates the need and associated expense of extra components and redundant safety systems required by other plant designs for protection against coolant leakages.
In April an Ansaldo subsidiary was contracted to design, provide, install and test key components of the reactor at the Versatile Lead Loop Facility and Passive Heat Removal Facility, which are to be designed and installed at Ansaldo Nuclear's site in Wolverhampton in the UK.
Beyond base-load electricity generation, the high-temperature operation of the LFR will allow for effective load-following capability enabled by an innovative thermal energy storage system, as well as delivery of process heat for industrial applications and water desalination.
A supercritical carbon dioxide power conversion system that uses air as the ultimate heat sink significantly reduces water utilization and eliminates the need for siting the plant near large water bodies.
The core is at the bottom of a metal-filled module sitting in a large pool of secondary molten metal coolant which also accommodates the eight separate and unconnected steam generators. There is convection circulation of primary coolant within the module and of secondary coolant outside it.
Outside the secondary pool the plant is air-cooled. Control rods would need to be adjusted every year or so and load-following would be automatic. The whole reactor sits in a 17 metre deep silo. After this the module is removed, stored on site until the primary lead or Pb-Bi coolant solidifies, and it would then be shipped as a self-contained and shielded item.
A new fuelled module would be supplied complete with primary coolant. The ENHS is designed for developing countries and is highly proliferation-resistant but is not yet close to commercialization. The heatpipe ENHS has the heat removed by liquid-metal heatpipes. The core is oriented horizontally and has a square rather than cylindrical cross-section for effective heat transfer. The heatpipes extend from the two axial reflectors in which the fission gas plena are embedded and transfer heat to an intermediate coolant that flows by natural circulation.
The SAFE space fission reactor — Safe Affordable Fission Engine — was a kWt heatpipe power system of kWe to power a space vehicle using two Brayton power systems gas turbines driven directly by the hot gas from the reactor. The STAR-LM is a factory-fabricated fast neutron modular reactor design cooled by lead-bismuth eutectic, with passive safety features.
Its MWt size means it can be shipped by rail. It uses uranium-transuranic nitride fuel in a 2. Decay heat removal is by external air circulation. Its development is further off. After a or year operating lifetime without refuelling, the whole reactor unit is then returned for recycling the fuel. The reactor vessel is 12 metres high and 3. SSTAR would eventually be coupled to a Brayton cycle turbine using supercritical carbon dioxide with natural circulation to four heat exchangers.
A prototype was envisaged for , but development has apparently ceased. Fuelled units would be supplied from a factory and operate for 30 years, then be returned. The concept is intended for developing countries. It has a subsidiary in Canada. The reactor vessel is designed to be small enough to permit transportation by aircraft. As the regulatory framework for licensing of small reactors in Canada is better established than in most other countries, Nunavut and the Northwest Territories are likely to become the first markets for SEALER units.
The Canadian Nuclear Safety Commission CNSC commenced phase 1 of a month pre-licensing vendor design review in January , but the review is now on hold at the vendor's request. In April the company began collaboration on safety analysis with Netherlands-based NRG, which operates the Petten high-flux research reactor. The plutonium and minor actinides present in the spent fuel will then be separated and converted into nitride fuel for recycle in a 10 MWe SEALER reactor.
The lead-cooled fast reactor would be able to generate 10 megawatts thermal, and is based on a Russian submarine reactor design.
It is working on a lead-bismuth cooled design of 35 MW which would operate on pyro-processed fuel. It is designed to be leased for 20 years and operated without refuelling, then returned to the supplier. It would then be refuelled at the pyro-processing plant and have a design life of 60 years. It would operate at atmospheric pressure, eliminating major concern regarding loss of coolant accidents.
These mostly use molten fluoride salts as primary coolant, at low pressure. Fast-spectrum MSRs use chloride salt coolant. In most designs the fuel is dissolved in the primary coolant, but in some the fuel is a pebble bed. A second campaign used U fuel, but the program did not progress to building a MSR breeder utilising thorium.
Much higher temperatures are possible but not yet tested. Heat is transferred to a secondary salt circuit and thence to steam o. The basic design is not a fast neutron reactor, but with some moderation by the graphite, may be epithermal intermediate neutron speed and breeding ratio is less than 1.
Thorium can be dissolved with the uranium in a single fluid MSR, known as a homogeneous design. Two-fluid, or heterogeneous MSRs would have fertile salt containing thorium in a second loop separate from the fuel salt containing fissile uranium and could operate as a breeder reactor MSBR.
In each case secondary coolant salt circuits are used. The fission products dissolve in the fuel salt and may be removed continuously in an on-line reprocessing loop and replaced with fissile uranium or, potentially, Th or U Actinides remain in the reactor until they fission or are converted to higher actinides which do so.
The liquid fuel has a negative temperature coefficient of reactivity and a strong negative void coefficient of reactivity, giving passive safety. If the fuel temperature increases, the reactivity decreases. The MSR thus has a significant load-following capability where reduced heat abstraction through the boiler tubes leads to increased coolant temperature, or greater heat removal reduces coolant temperature and increases reactivity.
Primary reactivity control is using the secondary coolant salt pump or circulation which changes the temperature of the fuel salt in the core, thus altering reactivity due to its strong negative reactivity coefficient.
The MSR works at near atmospheric pressure, eliminating the risk of explosive release of volatile radioactive materials. Other attractive features of the MSR fuel cycle include: the high-level waste comprising fission products only, hence shorter-lived radioactivity actinides are less-readily formed from U than in fuel with atomic mass greater than ; small inventory of weapons-fissile material Pu being the dominant Pu isotope ; high temperature operation giving greater thermal efficiency; high burn-up of fuel and hence low fuel use the French self-breeding variant claims 50kg of thorium and 50kg U per billion kWh ; and safety due to passive cooling up to any size.
Several have freeze plugs so that the primary salt can be drained by gravity into dump tanks configured to prevent criticality. Control rods are actually shut-down rods. Lithium used in the primary salt must be fairly pure Li-7, since Li-6 produces tritium when fissioned by neutrons.
Li-7 has a very small neutron cross section. This means that natural lithium must be enriched, and is costly. Pure Li-7 is not generally used in secondary coolant salts.
But even with enriched Li-7, some tritium is produced and must be retained and recovered. The MSR concept is being pursued in the Generation IV programme with two variants: one a fast neutron reactor with fissile material dissolved in the circulation fuel salt, and with solid particle fuel in graphite and the salt functioning only as coolant.
Molten fluoride salts possibly simply cryolite — Na-Al fluoride are a preferred interface fluid in a secondary circuit between the nuclear heat source and any chemical plant. The aluminium smelting industry provides substantial experience in managing them safely. One MSR developer, Moltex, has put forward a molten salt heat storage concept GridReserve to enable the reactor to supplement intermittent renewables.
When electricity demand is low, the heat from a MWe Stable Salt Reactor SSR, see below can be transferred to a nitrate salt held in storage tanks for up to eight hours, and later used to drive a turbine when demand rises. While MSR technology has been researched in many countries for decades, it is generally perceived that licensing MSRs is a major challenge and that in general there is so far very limited experience in design or operation of MSRs. See also Molten Salt Reactors information paper for more detail of the designs described below.
Some of the neutrons released during fission of the U salt in the reactor core are absorbed by the thorium in the blanket salt. The resulting U is separated from the blanket salt and in FLiBe becomes the liquid core fuel.
LFTRs can rapidly change their power output, and hence be used for load-following. Flibe Energy in the USA is studying a 40 MW two-fluid graphite-moderated thermal reactor concept based on the s-'70s US molten-salt reactor programme. Fuel is uranium bred from thorium in FLiBe blanket salt.
Fuel salt circulates through graphite logs. Secondary loop coolant salt is sodium-beryllium fluoride BeF 2 -NaF. It can consume plutonium and actinides, and be from to MWe. Several variants have been designed, including a 10 MWe mini Fuji. This simplified MSR integrates the primary reactor components, including primary heat exchangers to secondary clean salt circuit, in a sealed and replaceable core vessel that has a projected life of seven years.
The moderator is a hexagonal arrangement of graphite elements. Secondary loop coolant salt is ZrF 4 -KF at atmospheric pressure. Emergency cooling and residual heat removal are passive.
Each plant would have space for two reactors, allowing a seven-year changeover, with the used unit removed for offsite reprocessing when it has cooled and fission products have decayed. Terrestrial Energy hopes to commission its first commercial reactor in the s.
The total levelized cost of electricity from the largest is projected to be competitive with natural gas. The smallest is designed for off-grid, remote power applications, and as prototype. In February the project progressed to stage 2 of site evaluation by Canadian Nuclear Laboratories — a separate process to licensing — in relation to possibly siting a commercial plant at Chalk River by In August the company signed an agreement with Westinghouse in the UK for fuel development and supply.
The other three sites are located east of the Mississippi. This is a concept for a small nuclear fission source providing heat by molten salt with no pumps or valves to power a commercial gas turbine of MWe.
No refuelling would be required for about ten years. The whole MsNB would be 3m diameter and 3m high. No other details. Idaho National Laboratory and Idaho University are involved. The revised TAP reactor design has a very compact core consisting of an efficient zirconium hydride moderator and lithium fluoride LiF based salt bearing uranium tetrafluoride UF 4 fuel as well as the actinides that are generated during operation.
The neutron flux is greater than with a graphite moderator, and therefore contributes strongly to burning of the generated actinides. Fission products would be continuously removed while small amounts of fresh fuel added, allowing the reactor to remain critical for decades.
Decay heat removal is by natural convection via a cooling stack. In September the company announced that it would cease operations and make its intellectual property freely available online. It is a single-fluid thorium converter reactor in the thermal spectrum, graphite moderated.
It uses a combination of U from thorium and low-enriched U Fuel salt is sodium-beryllium fluoride BeF 2 -NaF with dissolved uranium and thorium tetrafluorides Li-7 fluoride is avoided for cost reasons.
Secondary loop coolant salt is also sodium-beryllium fluoride. There is no online processing — this takes place in a centralized plant at the end of the core life — with off-gassing of some fission products meanwhile. Each module contains two replaceable reactors in sealed 'cans'. Each can is The cans sit in silos below grade 30 m down. Below each is a cylinder fuel salt drain tank, under a freeze valve. At any one time, just one of the cans of each module is producing power.
The other can is in cool-down mode. Every four years the can that has been cooling is removed and replaced with a new can. The fuel salt is transferred to the new can, and the can that has been operating goes into cool-down mode. Because the nuclear material is contained in fuel assemblies, standard industrial pumps can be used for the low radioactivity coolant salt.
Decay heat is removed by natural air convection. Fuel tubes three-quarters filled with the molten fuel salt are grouped into fuel assemblies which are similar to those used in standard reactors, and use similar structural materials. The individual fuel tubes are vented so that noble fission product gases escape into the coolant salt, which is a ZrF 4 -KF-NaF mixture, the radionuclide accumulation of which is managed. Iodine and caesium stay dissolved in the fuel salt.
Other fission product gases condense on the upper fuel tube walls and fall back into the fuel mixture before they can escape into the coolant. The fuel assemblies can be moved laterally without removing them. Refuelling is thus continuous online, and after the fuel is sufficiently burned up the depleted assemblies are stored at one side of the pool for a month to cool, then lifted out so that the salt freezes.
Reprocessing is straightforward, and any level of lanthanides can be handled. SSR factory-produced modules are MWe containing fuel, pumps, primary heat exchanger, control blades and instrumentation.
Several, up to gigawatt-scale, can share a reactor tank, half-filled with the coolant salt which transfers heat away from the fuel assemblies to the peripheral steam generators, essentially by convection, at atmospheric pressure. The GridReserve version has heat storage. The SSR-W is the simplest and cheapest, due to compact core and no moderator. The primary fissile fuel in this original fast reactor version was to be plutonium chloride with minor actinides and lanthanides, recovered from LWR fuel or from an SSR-U reactor.
Secondary coolant is nitrate salt buffer. In April plans were confirmed for this plus a plant for recycling used Canadian nuclear fuel for it. The first operating reactor is envisaged after As well as electricity, hydrogen production is its purpose. It is designed to be compatible with thorium breeding to U It is seen as having a much larger potential market, and initial deployment in the UK in the s is anticipated, with potential for replacing CCGT and coal plants.
The SSR-Th is a thorium breeder version of the SSR-U, with thorium in the coolant salt and the U produced is progressively dissolved in bismuth at the bottom of the salt pool. This contains U to denature it and ensure there is never a proliferation risk. If the fuel is used in a fast reactor, plutonium and actinides can be added. Moltex has also put forward its GridReserve molten nitrate salt heat storage concept to enable the reactor to supplement intermittent renewables.
No details are available except that fuel is in the salt, and there is nothing in the core except the fuel salt. As a fast reactor it can burn U, actinides and thorium as well as used light water reactor fuel, requiring no enrichment apart from initial fuel load these details from TerraPower, not Southern.
It is reported to be large. In August Southern Nuclear Operating Company signed an agreement to work with X-energy to collaborate on development and commercialization of their respective small reactor designs. It will not require refuelling during its operational life. Core Power aims to partner with technology developers to enable deployment of the marine MSR, including amending maritime regulations for wide acceptance of m-MSR powered ships worldwide.
It operates below grade at near atmospheric pressure. It is designed to load-follow. Selected fission products are removed online. Passive safety includes a freeze plug. It has negative temperature and void coefficients. See also information page on Molten Salt Reactors. Fuel salt is Li-7 fluoride initially with uranium as fluoride.
Later, thorium, plutonium and minor actinides as fluorides are envisaged as fuel, hence the reactor being called a waste burner. This is pumped through the graphite column core and heat exchanger.
Fission products are extracted online. Spent LWR fuel would have the uranium extracted for recycle, leaving plutonium and minor actinides to become part of the MSR fuel, with thorium. The company claims very fast power ramp time. High temperature output will allow application to hydrogen production, synthetic fuels, etc. In March the public funding agency Innovation Fund Denmark made a grant to Seaborg to "build up central elements in its long-term strategy and position itself for additional investments required to progress towards commercial maturity.
Seaborg aims to deploy the first full-scale prototype power barge by This was a pre-conceptual US design completed in to evaluate the potential benefits of fluoride high-temperature reactor FHR technology. It is designed for modular construction, and from MWe base-load it is able to deliver MWe with gas co-firing for peak loads. Fuel pebbles are 30 mm diameter, much less than gas-cooled HTRs.
The project looked at how FHRs might be coupled to a Brayton combined-cycle turbine to generate power, design of a passive decay heat removal system, and the annular pebble bed core. While similar to the gas-cooled HTR it operates at low pressure less than 1 atmosphere and higher temperature, and gives better heat transfer than helium. This could be used in thermochemical hydrogen manufacture. It is truck transportable, being 9m long and 3. Fuel is Refuelling interval is 2. Secondary coolant is FLiNaK to Brayton cycle, and for passive decay heat removal, separate auxiliary loops go to air-cooled radiators.
The reactor uses It has passive shutdown and decay heat removal. TVA holds an early site permit for the Clinch River site. This is also known as the fluoride salt-cooled high-temperature reactor FHR. A MWt demonstration pebble-bed plant with open fuel cycle is planned by about China claims to have the world's largest national effort on these and hopes to obtain full intellectual property rights on the technology. The target date for TMSR deployment is Aqueous homogeneous reactors AHRs have the fuel mixed with the moderator as a liquid.
Typically, low-enriched uranium nitrate is in aqueous solution. About 30 AHRs have been built as research reactors and have the advantage of being self-regulating and having the fission products continuously removed from the circulating fuel. Further detail is in the Research Reactors paper. A theoretical exercise published in showed that the smallest possible thermal fission reactor would be a spherical aqueous homogenous one powered by a solution of Amm NO 3 3 in water.
Its mass would be 4. Power output would be a few kilowatts. Possible applications are space program and portable high-intensity neutron source. The small size would make it easily shielded. Distinct from other small reactor designs, heatpipe reactors use a fluid in numerous sealed horizontal steel heatpipes to passively conduct heat from the hot fuel core where the fluid vapourises to the external condenser where the fluid releases latent heat of vapourisation with a heat exchanger.
The principle is well established on a small scale, but here a liquid metal is used as the fluid and reactor sizes up to several megawatts are envisaged. There is a large negative temperature reactivity coefficient. There is very little decay heat after shutdown.
Experimental work on heatpipe reactors for space has been with very small units about kWe , using sodium as the fluid. They have been developed since at Los Alamos National Laboratory LANL as a robust and low technical risk system for space exploration with an emphasis on high reliability and safety, the Kilopower fast reactor being the best-known design.
Heatpipe microreactors may have thermal, epithermal or fast neutron spectrums, but above kWe they are generally fast reactors. It is generally perceived that licensing heatpipe reactors is a major challenge and that there is very limited or no experience in design or operation of them. Units would have a year lifetime with three-year refuelling interval. They would be transportable, with setup under 30 days. The units would have 'walk-away' safety due to inherent feedback diminishing the nuclear reaction with excess heat, also effecting load-following.
There are multiple fuel options for the eVinci, including uranium in oxide, metallic and silicide form. Westinghouse is aiming to complete the design, testing, analysis and licensing to build a demonstration unit by , test by , and have the eVinci ready for commercial deployment by A megawatt hour Mwh is equal to 1, Kilowatt hours Kwh. It is equal to 1, kilowatts of electricity used continuously for one hour. If you use Watts or 1 Kilowatt of power for 1 hour then you consume 1 unit or 1 Kilowatt-Hour kWh of electricity.
So the reading on the electricity meter represents the actual electricity used. Some generators are even lower. On average, depending on their size, home refrigerators need around starting watts.
The generator that can deliver at least starting watts will be sufficient to run both the refrigerator and the freezer without problems.
Refrigerators are reactive devices that require additional power to start because they contain an electric motor, but significantly fewer watts to run as they remain on. Merchant coke plant: A coke plant where coke is produced primarily for sale on the commercial open market. Merchant facilities: High-risk, high-profit facilities that operate, at least partially, at the whims of the market, as opposed to those facilities that are constructed with close cooperation of municipalities and have significant amounts of waste supply guaranteed.
Production from these units is sold under contract or on the spot market to refiners or other gasoline blenders. Merchant oxygenate plants: Oxygenate production facilities that are not associated with a petroleum refinery. Production from these facilities is sold under contract or on the spot market torefiners or other gasoline blenders.
Mercury vapor lamp: A high-intensity discharge lamp that uses mercury as the primary light-producing element. Includes clear, phosphor coated, and self-ballasted lamps. Merger: A combining of companies or corporations into one, often by issuing stock of the controlling corporation to replace the greater part of that of the other.
Met: An approximate unit of heat produced by a resting person, equal to about Meta-anthracite: See Anthracite. Metal halide lamp: A high-intensity discharge lamp type that uses mercury and several halide additives as light-producing elements. They can be used for commercial interior lighting or for stadium lights.
Metallic: The metallic material composition of the collector's absorber system. Metallurgical coal: Coking coal and pulverized coal consumed in making steel. Metered data: End-use data obtained through the direct measurement of the total energy consumed for specific uses within the individual household. Individual appliances can be submetered by connecting the recording meters directly to individual appliances.
Metered peak demand: The presence of a device to measure the maximum rate of electricity consumption per unit of time. This device allows electric utility companies to bill their customers for maximum consumption, as well as for total consumption. Methane CH 4 : A colorless, flammable, odorless hydrocarbon gas which is the major component of natural gas. It is also an important source of hydrogen in various industrial processes. Methane is a greenhouse gas. See also Greenhouse gases.
Methanogens: Bacteria that synthesize methane, requiring completely anaerobic conditions for growth. Methanol blend: Mixtures containing 85 percent or more or such other percentage, but not less than 70 percent by volume of methanol with gasoline. Pure methanol is considered an "other alternative fuel. Methanotrophs: Bacteria that use methane as food and oxidize it into carbon dioxide.
Methyl chloroform trichloroethane : An industrial chemical CH 3 CC l3 used as a solvent, aerosol propellant, and pesticide and for metal degreasing. Methylene chloride: A colorless liquid, nonexplosive and practically nonflammable. Used as a refrigerant in centrifugal compressors, a solvent for organic materials, and a component in nonflammable paint removers.
Metric conversion factors for floorspace : Floorspace estimates may be converted to metric units by using the relationship, 1 square foot is approximately equal to. Energy estimates may be converted to metric units by using the relationship, 1 Btu is approximately equal to 1, joules.
One kilowatthour is exactly 3,, joules. One gigajoule is approximately kilowatthours kWh. Metric ton mt : A unit of weight equal to 2, Metropolitan: Located within the boundaries of a metropolitan area. Metropolitan area: A geographic area that is a metropolitan statistical area or a consolidated metropolitan statistical area as defined by the U. Office of Management and Budget. Metropolitan statistical area MSA : A county or group of contiguous counties towns and cities in New England that has 1 at least one city with 50, or more in habitants; or 2 an urbanized area of 50, inhabitants and a total population of , or more inhabitants 75, in New England.
These areas are defined by the U. The contiguous counties or other jurisdictions to be included in an MSA are those that, according to certain criteria, are essentially metropolitan in character and are socially and economically integrated with the central city or urbanized area. Microcrystalline wax: Wax extracted from certain petroleum residues having a finer and less apparent crystalline structure than paraffin wax and having the following physical characteristics penetration at 77 degrees Fahrenheit D maximum; viscosity at degrees Fahrenheit in Saybolt Universal Seconds SUS ; D88 SUS Microgroove: A small groove scribed into the surface of a solar photovoltaic cell which is filled with metal for contacts.
Micrometer or Micron : One-millionth of a meter. It can also be expressed as meter. Microwave oven: A household cooking appliance consisting of a compartment designed to cook or heat food by means of microwave energy. It may also have a browning coil and convection heating as additional features.
Mid-size passenger car: A passenger car with between and cubic feet of interior passenger and luggage volume. Middle distillates: A general classification of refined petroleum products that includes distillate fuel oil and kerosene. Middlings: In coal preparation, this material called mid-coal is neither clean nor refuse; due to their intermediate specific gravity, middlings sink only partway in the washing vessels and are removed by auxiliary means.
Midgrade gasoline: Gasoline having an antiknock index, i. Note: Octane requirements may vary by altitude. See Octane Rating. Miles per gallon MPG : A measure of vehicle fuel efficiency. MPGs are assigned to each vehicle using the EPA certification files and adjusted for on-road driving. Mill capital: Cost for transportation and equipping a plant for processing ore or other feed materials. Mill feed: Uranium ore supplied to a crusher or grinding mill in an ore-dressing process.
Milling: The grinding or crushing of ore, concentration, and other beneficiation, including the removal of valueless or harmful constituents and preparation for market. Milling capacity: The maximum rate at which a mill is capable of treating ore or producing concentrate. Milling of uranium: The processing of uranium from ore mined by conventional methods, such as underground or open-pit methods, to separate the uranium from the undesired material in the ore.
See Btu. Minable: Capable of being mined under current mining technology and environmental and legal restrictions, rules, and regulations. Mine capital: Cost for exploration and development, pre-mining stripping, shaft sinking, and mine development including in-situ leaching , as well as the mine plant and its equipment.
Mine count: The number of mines, or mines collocated with preparation plants or tipples, located in a particular geographic area state or region. If a mine is mining coal across two counties within a state, or across two states, then it is counted as two operations. This is done so that EIA can separate production by state and county.
Mineral: Any of the various naturally occurring in organic substances, such as metals, salt, sand, stone, sulfur, and water, usually obtained from the earth. Note For reporting on the Financial Reporting System the term also includes organic non-renewable substances that are extracted from the earth such as coal, crude oil, and natural gas.
Mineral lease: An agreement wherein a mineral interest owner lessor conveys to another party lessee the rights to explore for, develop, and produce specified minerals.
The lessee acquires a working interest and the lessor retains a non-operating interest in the property, referred to as the royalty interest, each in proportions agreed upon. Mineral rights: The ownership of the minerals beneath the earth's surface with the right to remove them. Mineral rights may be conveyed separately from surface rights.
Mineral-matter-free basis: Mineral matter in coal is the parent material in coal from which ash is derived and which comes from minerals present in the original plant materials that formed the coal, or from extraneous sources such as sediments and precipitates from mineralized water. Mineral matter in coal cannot be analytically determined and is commonly calculated using data on ash and ash-forming constituents.
Coal analyses are calculated to the mineral matter free basis by adjusting formulas used in calculations in order to deduct the weight of mineral matter from the total coal. Minimum streamflow: The lowest rate of flow of water past a given point during a specified period.
Mining: An energy-consuming subsector of the industrial sector that consists of all facilities and equipment used to extract energy and mineral resources. Minivan: Small van that first appeared with that designation in Any of the smaller vans built on an automobile-type frame. Earlier models such as the Volkswagen van are now included in this category.
Minority carrier: A current carrier, either an electron or a hole, that is in the minority in a specific layer of a semiconductor material; the diffusion of minority carriers under the action of the cell junction voltage is the current in a photovoltaic device.
Miscellaneous petroleum products: Includes all finished products not classified elsewhere e.
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