how does a molten salt reactor work
It would proceed to a continuous process of recycling salt, uranium and thorium, with online separation of fission products and minor actinides. Unlike the ... IV reactors is molten sodium. Here, the U-233 is progressively removed* and transferred to the primary circuit. * There was no breeding blanket, this being omitted for simplicity in favour of neutron measurements. The Generation IV international Forum (GIF) mentions 'salt processing' as a technology gap for MSRs, putting the initial focus clearly on burners rather than breeders. Fast Spectrum Molten Salt Reactor Options. The 10 MWt TMSR-SF1 will have TRISO fuel in 60mm pebbles, similar to HTR-PM fuel, and deliver coolant at 650°C and low pressure. The fast neutron spectrum allows the possibility of not having onsite processing to remove TRUs. LiF however can carry a higher concentration of uranium than FLiBe, allowing less enrichment. Argonne National Laboratory. Sodium-beryllium fluoride (BeF2-NaF) solidifying at 385°C is used as fuel salt in one design for cost reasons. Compact Molten Salt Reactor Their aim is to make small reactors which they can mass produce in a central location and transport to customers. Fuel is 19.75% enriched uranium in TRISO particles in graphite blocks or fuel plates. Secondary coolant salt is FLiNaK, at 700°C. The assemblies can be moved laterally without removing them. The liquid fluoride thorium reactor (LFTR) is a heterogeneous MSR design which breeds its U-233 fuel from a fertile blanket of lithium-beryllium fluoride (FLiBe) salts with thorium fluoride. You may be able to find more information about this and similar content at piano.io, If There Were Aliens, They Killed Themselves Off, Genetically Modified Pigs Might Save Your Life, This TikTok Star Uses Math to Guess Your Height, This Solar Cell Just Set an Efficiency Record, This Incredible Particle Only Arises in Two Dimens, We Already Know How to Build a Time Machine, Whoops, Humans Made a Space Barrier Around Earth, US Department of Energy Nuclear Energy Research Advisory Committee. A Liquid Fluoride Thorium Reactor (LFTR) is a type of Molten Salt Reactor (MSR) that can use inexpensive Thorium for fuel (thorium becomes uranium inside the reactor). Batch reprocessing is likely in the short term, and fuel life is quoted at 4-7 years, with high burn-up. The original objectives of the MSRE were achieved by March 1965, and the U-235 campaign concluded. A 20-year operating life is envisaged. The defining work was done on them at the Oak Ridge National Laboratory in Tennessee in the 1950s through the 1970s. The refuelling interval is 2.5 to 4 years depending on fuel configuration. Instead, the fuel is dissolved into a liquid salt mixture, at high temperature (450-750 o C). The nitty gritty results of experiments like this are critical to building a wider understanding of molten salt, especially when corrosion and other unanticipated engineering issues have been cited as one of the major obstacles to the technology by the NREL. Molten salt reactors (MSRs) use molten fluoride salts as primary coolant, at low pressure. Thorium may also be used, though it is described as a burner-converter rather than a breeder. Fuel tubes of nickel-chromium alloy three-quarters filled with the molten fuel salt (60% NaCl, 40% Pu, U & lanthanide trichlorides) are grouped into fuel assemblies which are similar to those used in standard reactors and use similar structural materials. It was the primary back-up option for the fast breeder reactor (cooled by liquid metal) and a small prototype 8 MWt Molten Salt Reactor Experiment (MSRE) operated at Oak Ridge over four years to 1969 (the MSR program ran 1957-1976). However, a limited market for this version is anticipated. it is a liquid-fuel design. Molten salt reactors (MSRs) are a Generation IV nuclear reactor that use molten salts (high temperature liquid salts) as their nuclear fuel in place of the conventional solid fuels used in the world's current reactors. As noted above, a 5 MW thorium-fuelled prototype is under construction at Shanghai Institute of Nuclear Applied Physics (SINAP, under the China Academy of Sciences) originally with a 2015 target for operation. It is designed for modular construction, and from 100 MWe base-load is able to deliver 242 MWe with gas co-firing for meeting peak loads. Moltex has also put forward its GridReserve molten salt heat storage concept to enable the reactor to supplement intermittent renewables. Oak Ridge National Laboratory 507,046 views. A 100 MWt demonstration pebble bed plant with open fuel cycle is planned by about 2025. It would be moderated by graphite with a four-year replacement schedule, use NaF-NaBF4 as the secondary coolant, and have a peak operating temperature of 705°C. It would work up from about 20% thorium fission to about 80%. In January 2016 the US DOE awarded a Gateway for Accelerated Innovation in Nuclear (GAIN) grant to the project, worth up to $40 million. It uses a combination of U-233 from thorium and low-enriched U-235 from mined uranium. The company claims generation costs of 3 to 5 c/kWh depending on scale, and is "targeting its first installations in forward-looking countries that support technology-neutral nuclear regulations and see the benefits of the license-by-test process.". As long as the pumps run, heat transfer will happen and the MSR will operate normally. by bubbling fluorine through the salt so that UF6 is formed and removed as a gas. The Molten Salt Fast Neutron Reactor (MSFR), which will take in thorium fuel cycle, recycling of actinides, closed Th/U fuel cycle with no U enrichment, with enhanced safety and minimal wastes. * e.g. 2004, An advanced molten salt reactor using high-temperature reactor technology, American Nuclear Society, LeBlanc, D, 2009, Molten Salt Reactors: a new beginning for an old idea, Nuclear Engineering & Design 2010, Elsevier, Transatomic Power Corp., technical white paper, March 2014, Ignatiev, V & Feynberg, O, Kurchatov Inst, Molten Salt Reactor: overview and perspectives, OECD 2012, Appendix 6.0 Molten Salt Reactor, Generation IV Nuclear Energy Systems Ten-Year Program Plan – Fiscal Year 2007, Department of Energy Office of Nuclear Energy (September 2007), Hargraves, R & Moir, R, 2010, Liquid Fluoride Thorium Reactors, American Scientist 98, Fluoride-Salt-Cooled High-Temperature Reactors (FHRs) for Base-Load and Peak Electricity, Grid Stabilization, and Process Heat, Forsberg, Hu, Peterson, Sridharan, 2013, MIT, Wong, C & Merrill, B, 2004, Relevant MSRE and MSR Experience, ITER TBM Project Meeting at UCLA, 23-25 February 2004. In the USA a consortium including UC Berkeley, ORNL and Westinghouse is designing a 100 MWe pebble bed FHR, with annular core. One MSR developer, Moltex, has put forward a molten salt heat storage concept (GridReserve) to enable the reactor to supplement intermittent renewables. In the MSBR, the reactor-grade U-233 bred in the secondary circuit needs to be removed, or it will fission there and contaminate that circuit with ‘hot’ fission products. The volatile uranium hexafluoride is captured, reduced back to soluble UF4 by hydrogen gas, and finally is added to the FLiBe core to serve as fissile fuel. et al, July 2011, Fast Spectrum Molten Salt Reactor Options, ORNL, © 2016-2020 World Nuclear Association, registered in England and Wales, number 01215741. It commenced in 2015. It uses a molten salt as coolant and fuel. Graphite as moderator is chemically compatible with the fluoride salts. In liquid-fuel MSR designs the fission products dissolve in the fuel salt and are ideally removed continuously in an adjacent online reprocessing loop and replaced with fissile uranium, plutonium and other actinides or, potentially, fertile Th-232 or U-238. Gear-obsessed editors choose every product we review. The secondary coolant is FLiNaK salt (LiF-KF-NaF) to a steam generator. The Advanced High-Temperature Reactor (AHTR) – also known as the fluoride salt-cooled high-temperature reactor (FHR) – with the same graphite and solid fuel core structures as the VHTR and molten salt as coolant instead of helium, enabling power densities 4 to 6 times greater than HTRs and power levels up to 4000 MWt with passive safety systems. With TerraPower and ORNL, X-energy is designing the Xe-100 pebble-bed HTR of 48 MWe. It is a single-fluid thorium converter reactor in the thermal spectrum, graphite moderated. Secondary coolant is FLiNaK to Brayton cycle, and for passive decay heat removal, separate auxiliary loops go to air-cooled radiators. A molten salt reactor (MSR) is a class of nuclear fission reactor in which the primary nuclear reactor coolant and/or the fuel is a molten salt mixture. Actinides are less-readily formed from U-233 than in fuel with atomic mass greater than 235. That's good because you want the fuel to absorb neutrons, not the other components of the salt. Later versions are intended to reach 850° to 1000°C, using materials yet to be developed. Two methods of tritium stripping are being evaluated, and also tritium storage. It was a time of creativity in reactor … The Molten-Salt Reactor Experiment - Duration: 20:32. The US Department of Energy is collaborating with the China Academy of Sciences on the program, which had a start-up budget of $350 million. A British design contains the chloride fuel salt in vertical tubes and relies on convection to circulate the secondary salt coolant, which is a fluoride mix. FLiBe with 99.95% Li-7 would be used, and fuel as UF4. MSRs would normally operate at much higher temperatures than LWRs – up to at least 700°C, and hence have potential for process heat. SSR factory-produced modules are 150 MWe containing fuel, pumps, primary heat exchanger, control blades and instrumentation. However having the fuel in solution also means that the primary coolant salt becomes radioactive, complicating maintenance procedures, and the chemistry of the salt must be monitored closely to maintain a chemically reduced state to minimise corrosion. Later (concurrently to MSR development),several AHR test reactors were built at Oak Ridge National Laboratory (these were the HomogeneousReactor Experiments HRE-1 and HRE-2). PuCl3 in NaCl has been well researched. However, graphite degradation from neutron flux limits the useful life of the reactor core with the fuel and breeding fluids in close juxtaposition, and in the 1960s it was assumed that the entire reactor vessel in the two-fluid design would be replaced after about eight years.**. The IMSR will operate at 600-700°C, which can support many industrial process heat applications. SINAP sees this design as having potential for higher temperatures than MSRs with fuel salt. Fission products are extracted on-line. It operates below grade at near atmospheric pressure and uses no water near the fuel salt. It appears that the postponement of building the 2 MW test reactor may be due to inadequate supplies of pure lithium-7. “Using NOMAD, Khaykovich was able to see how each positively charged chromium ion attracted six negative chlorine ions. It can consume plutonium and actinides, and be from 100 to 1000 MWe. Much of the interest today in reviving the MSR concept relates to using thorium (to breed fissile uranium-233), where an initial source of fissile material such as plutonium-239 needs to be provided. This is in contrast to water circulating through a highly pressurized cooling system and solid fuel, both of which are the signature features of Generation I, II and III conventional reactors. Freeze plugs to drain the fuel salt are a further passive safety measure as in other MSRs. Two-fluid, or heterogeneous MSRs, would have fertile salt containing thorium in a second loop separate from the fuel salt containing fissile uranium or plutonium and could operate as a breeder reactor (MSBR). Otherwise, newly-formed U-233 forms soluble uranium tetrafluoride (UF4), which is converted to gaseous uranium hexafluoride (UF6) by bubbling fluorine gas through the salt (which does not chemically affect the less-reactive thorium tetrafluoride). The SSR-W is simplest and cheapest, due to compact core and no moderator. It is seen as having a much larger potential market, and initial deployment in the UK in the 2030s is anticipated, with potential for replacing CCGT and coal plants. NOMAD features high-temperature sample environments that allow samples to be heated to over 1500°F before they are studied with neutron diffractometry,” Oak Ridge National Laboratory (ORNL) said in a statement. As a result, chlorine ions are on average closer together than they are in pure molten sodium chloride,” the statement explains. In industrial applications 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. LFTRs are defined by the use of fluoride fuel salts and the breeding of thorium into uranium-233 in … It is being developed internationally by a Japanese, Russian and US consortium: the International Thorium Molten Salt Forum (ITMSF), based in Japan. “[E]xtending the concept to dissolving the fissile and fertile fuel in the salt certainly represents a leap in lateral thinking relative to nearly every reactor operated so far,” the World Nuclear Association explains. This may be within a single unit as the ratio of U-238 to transuranics (TRU) is varied – less U-238 giving more fission. Most of the problems the NREL described are structural, because salt solutions just aren’t well understood in high-temperature nuclear contexts the same way water is after decades of regular use in power plants. A 2 MWt pilot plant is envisaged, and eventually 2225 MWt commercial plants. Owing to the ZrH moderator, there are significantly more neutrons in the thermal region (less than 1 eV) compared with a graphite moderator, thereby enabling the reactor to generate power from very low-enriched uranium or used LWR fuel. A molten salt reactor (MSR) is a type of nuclear reactor that uses liquid fuel instead of the solid fuel rods used in conventional nuclear reactors. This could be used in thermochemical hydrogen manufacture. In new molten salt plant designs, which don’t need to rely on water-based precedents and can introduce next-generation nuclear technology, the nuclear fuel could be dissolved into the medium of molten salt. Core height is 3 m, diameter 2.85 m, in a 7.8 m high and 3 m diameter pressure vessel. Fission products are mostly removed batch-wise and fresh fuel added. In the first campaign (1965-68), uranium-235 tetrafluoride (UF4) enriched to 33% was dissolved in molten lithium, beryllium and zirconium fluorides at 600-700°C which flowed through a graphite moderator at ambient pressure. Beyond these, a 373 MWt/168 MWe liquid-fuel MSR small modular reactor is planned, with supercritical CO2 cycle in a tertiary loop at 23 MPa using Brayton cycle, after a radioactive isolation secondary loop. Studying each part in detail now will help engineers make better designs going forward. The conventional water- cooled reactors of the past half-century have proven volatile to a variety of safety standards. Kirk formed the company Flibe Energy back in 2011. The TMSR-SF0 simulator is one-third scale, with FLiNaK cooling and a 400 kW electric heater. Compared with solid-fuelled reactors, MSR systems with circulating fuel salt are claimed to have lower fissile inventories*, no radiation damage constraint on fuel burn-up, no requirement to fabricate and handle solid fuel or solid used fuel, and a homogeneous isotopic composition of fuel in the reactor. The nuclear energy sector has been plagues by a plethora of challenges in recent decades in regard to sufficiently and safely supplying the clean energy that first drove its expansion. Hence fissile plutonium is largely consumed, and contributes significant energy. Meanwhile caesium and iodine in particular remain secure in the molten salt. Most secondary coolant salts do not use lithium, for cost reasons. It is favoured in MSR and AHTR primary cooling and when uncontaminated has a low corrosion effect. Molten salt reactors, as a class, include both burners and breeders in fast or thermal spectra, using fluoride or chloride salt-based fuels and a range of fissile or fertile consumables. In the thorium breeder version of SSR-U, thorium would be in the coolant salt and the U-233 produced is progressively dissolved in bismuth at the bottom of the salt pool. The UF6 is reduced and added to the fuel stream. We may earn commission if you buy from a link. The epithermal (1 eV - 1 MeV) spectrum is lower than that with graphite, but in the fast spectrum (over 1 MeV) the neutron flux is greater than with graphite moderator, and therefore contributes strongly to actinide burning. Seaborg Technologies in Denmark has a thermal-epithermal single fluid reactor design for 50 MWt pilot unit with a view to 250 MWt commercial modular units fuelled by spent LWR fuel and thorium. Consortium including UC Berkeley, ORNL and Westinghouse is designing the Xe-100 pebble-bed HTR 48... 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