Liquid fluoride thorium reactor

The liquid fluoride thorium reactor (acronym LFTR; spoken as lifter) is a thermal breeder reactor which uses the thorium fuel cycle in a fluoride-based molten (liquid) salt fuel to achieve high operating temperatures at atmospheric pressure.

The LFTR is a type of thorium molten salt reactor (TMSR). Molten-salt-fueled reactors (MSFRs) such as LFTR, where the nuclear fuel itself is in the form of liquid molten salt mixture, should not be confused with only molten-salt-cooled but solid-fueled reactors.

This technology was first investigated at the Oak Ridge National Laboratory Molten-Salt Reactor Experiment in the 1960s. It has been recently investigated by Japan, China, the UK, and private US and Australian interests. Flibe Energy aims to develop a small modular reactor version using liquid FLiBe salt.

Contents 1 Background 2 Two versus Single fluid 2.1 Two Fluid Reactor 2.2 Single Fluid Reactor 3 Advantages 3.1 Safety 3.2 Economy and efficiency 3.3 Ease of reprocessing 4 Disadvantages 5 Design challenges 6 Recent developments 6.1 The Fuji MSR 6.2 Chinese Thorium MSR project 6.3 Flibe Energy 6.3.1 Small modular design 6.4 The Weinberg Foundation 7 See also 8 References 9 Further reading 10 External links

Background

By 1946, only eight years after the discovery of nuclear fission, three fissile isotopes had been publicly identified for use as nuclear fuel:^[1][2]

• Uranium-235, which is already fissile, but occurs as <1% of natural uranium
• Plutonium-239, which can be bred from non-fissile Uranium-238 (>99% of natural uranium)
• Uranium-233, which can be bred from non-fissile Thorium-232 (~100% of natural thorium; about four times more common than uranium^[3])

Th-232, U-235 and U-238 are primordial nuclides, having existed in their current form for over 4.5 billion years, predating the formation of the Earth; they were forged in the cores of dying stars through the r-process and scattered across the galaxy by supernovas.^[4] Their radioactive decay produces about half of the earth's internal heat.^[5]

For technical reasons (outlined in a section below), the three are each best suited to different reactor types. U-235 is the world's primary nuclear fuel and is usually used in light water reactors. U-238/Pu-239 has found the most use in liquid sodium fast breeder reactors. Th-232/U-233 is best suited to molten salt reactors (MSR).^[3]

Alvin M. Weinberg pioneered the use of the MSR at Oak Ridge National Laboratory. The Aircraft Reactor Experiment in 1954 and Molten-Salt Reactor Experiment from 1965 to 1969 both used liquid fluoride salts; the latter notably demonstrated the use of U-233 as a fuel source.^[6] Unfortunately for MSR research, Weinberg was fired and the MSR program closed down in the early 1970s,^[7] after which research stagnated in the United States.^[8][9]

The following reasons are cited as responsible for the program cancellation in January 1973:

1. The political and technical support for the program in the United States was too thin geographically. Within the United States, only in Oak Ridge, Tennessee, was the technology really understood and appreciated.

2. The MSR program was in competition with the fast breeder program at the time, which got an early start and had copious government development funds being spent in many parts of the United States. When the MSR development program had progressed far enough to justify a greatly expanded program leading to commercial development, the AEC could not justify the diversion of substantial funds from the LMFBR to a competing program.^[10]

Two versus Single fluid

Two concepts were investigated at Oak Ridge, the "two fluid" and "single fluid" thorium thermal breeder molten salt reactors:

Two Fluid Reactor

The "two fluid" reactor has a high-neutron-density core that burns uranium-233 from the thorium fuel cycle. A separate blanket of thorium salt absorbs the neutrons and eventually is transmuted to ²³³U fuel.^[11]

The advantage of the two-fluid design is a simplified chemical system to process the salts. In particular, protactinium-233 is separated from the thorium blanket in a two step process that uses bismuth and fluorination. Protactinium 233 has a 27 day half-life, and decays to the needed fuel, U233. So 10 months after the Protactinium is chemically separated from the salt, it is 99.9% U233. The kernel's salt is also purified, first by fluorination to remove uranium, then vacuum distillation to remove and reuse light-atomic-weight carrier salts. The still bottoms left after the distillation are the fission products of the waste.

The design weakness of the two-fluid design was its complex plumbing. The design used brittle graphite pipes to hold the fuel salt. The pipes separated the fuel salt and breeding salt, so they were essential. The problem is that graphite expands under intense neutron bombardment. So, graphite pipes would change length, crack and become very leaky. Graphite was the only known substance that combined the needed properties: It is not dissolved by the salt, it must survive the neutron bombardment, it must not absorb a lot of neutrons, it must survive at very high temperatures, and it must be tough enough not to crack. Zirconium alloys would work, except they dissolve in the salt. In modern research, copper-reinforced graphite fiber cloth seems theoretically suitable, but no physical tests have been done.^[12] At the time, no solution was known, so this type of reactor was never constructed.^[13]

The recovery of high-purity Uranium 233 has been raised as a potential nuclear proliferation concern.^[14](p99) Most LFTR advocates thus prefer a design with no Pa separation and a breeding ratio ~1.0, not presenting the risk of U-233 separation and ensuring that any U-233 is contaminated with U-232 whose decay chain emits 2 MeV gamma rays too hazardous for weapons workers.

Single Fluid Reactor

The "single fluid" reactor was mechanically much simpler, and was actually prototyped (as the MSRE, above.) It was a large tank filled with salt. The moderator was graphite rods immersed in the salt. The engineers discovered that by carefully sculpting the moderator rods (to get neutron densities similar to a core and blanket), and modifying the fuel reprocessing chemistry, both thorium and uranium salts could coexist in a simpler, less expensive yet efficient "one fluid" reactor.^[15] The MSRE provided valuable long-term operating experience.

The disadvantage was that the reprocessing chemistry was much more complex. No simple combination of distillation and fluorination (simple, proven methods) could separate the fission products (the nuclear ashes) from the fuels.

The power reactor design produced by Weinberg's research group was similar to the MSRE. This was because the MSRE was designed to test the design of the risky, hot, high-neutron-density "kernel" part of the two fluid "kernel and blanket" thorium breeder (see above).

Advantages

Thorium-fueled molten salt reactor offers many potential advantages:^[16]

Safety

• inherently safe design: reactor features passive nuclear safety, strong negative temperature coefficient of reactivity and atmospheric operating pressure. (since the core is not pressurised, it cannot explode)
• Most MSFRs include a freeze plug at the bottom that has to be actively cooled, usually by a small electric fan. If the cooling fails, say because of a power failure, the fan stops, the plug melts, and the fuel drains to a subcritical storage facility, totally stopping the reactor.
• Reduced radiotoxicity of reactor wastes. The LFTR uses the Thorium fuel cycle, which transmutes Thorium to U233. U233 has two chances to fission as a thermal reactor bombards it with neutrons (as U233 and U235). The fraction of fuel reaching U236, and transmuting into a transuranic element is less than 0.1%.^[17] The radiotoxicity of the remaining fission products is dominated by Cesium 137 and Strontium 90. The longer half-life is Cesium, at 30.17 years. So, after 300 years, decay reduces the radioactivity of the cesium to only 0.1%. A related advantage is that the U233 is relatively pure, without other isotopes that are not fuels. In contrast, Uranium fuels are between 97% and 80% U238, which reactors normally transmute to Pu239, a toxic transuranic isotope. When the two features are combined, the effect of a Thorium fuel cycle is to reduce the production of transuranic wastes by more than a thousand-fold compared to a conventional once-through light-water reactor.
• continuous removal of transmutation products insures that only a small amount of them is present in an active reactor at any given time, compared to conventional LWR reactors.
• fluoride combines ionically with almost any transmutation product. This is an MSFR's first level of containment. It is especially good at containing biologically active "salt loving" wastes such as Cesium 137.
• given an accident beyond the design basis for the multiple levels of containment, dispersion into a biome is difficult. The salts do not burn, explode or degrade in air or water, and the fluoride salts of the radioactive actinides and fission products are generally not soluble in water or air.
• the reactor is easy to control at all times. Xenon-135, an important neutron absorber — that makes reactors difficult to control is removed at a predictable, containable place, where the fuel is coolest and most dispersed, namely the pump bowl. In solid-fuel reactors, it remains in the fuel and interferes with control.
• the reactor operates at or above 650C, well above the 250C Wigner annealing temperature of graphite. This means that Wigner energy cannot accumulate in the graphite moderator. The continual annealing bleeds it off. So, a sudden release of Wigner energy is not possible, and as such, a Windscale-style graphite-incited fire cannot be caused by the graphite's nonexistent Wigner energy.
• proliferation resistance: LFTR produces only at most 9% more fuel than it burns in each year. Building bombs quickly will take power plants out of operation. Also, an easy variation of the thorium fuel cycle would contaminate the thorium-232 breeding material with chemically inseparable thorium-230. The thorium-230 breeds into uranium-232, which has a powerful gamma-ray emitter in its decay chain (thallium-208) that makes the reactor fuel 233U/232U impractical in a bomb,^[18] because it complicates bomb manufacture, harms electronics and reveals the bomb location.

Economy and efficiency

• LFTR uses an abundant world supply of thorium to breed uranium-233 fuel. The Earth's crust contains about three times as much thorium as 238U, or 400 times as much as 235U, which makes it about as abundant as lead. Thorium, a byproduct of rare-earth mining normally discarded as waste currently costs US$ 30/kg, while the price of uranium has risen above $100/kg, not including the cost of enrichment, and fuel element fabrication. When used in a LFTR, there is enough economically recoverable thorium on Earth to satisfy the global energy needs for hundreds of thousands of years.^[19] In addition to thorium, LFTR can also use nuclear waste from traditional nuclear power plants as a fuel
• conventional reactors consume less than one percent of their uranium fuel, leaving the rest as waste. LFTR consumes 99% of its thorium fuel, which results in great increase in fuel efficiency - 1 tonne of natural thorium in a LFTR produces as much energy as 35 t of enriched uranium in conventional reactors (requiring 250 t of natural uranium),^[3] or 4 166 000 tonnes of black coal in a coal power plant.

• since all natural thorium can be used as a fuel, and the fuel is in the form of a molten salt instead of solid fuel rods, expensive fuel enrichment and solid fuel rods validation procedure and fabricating process is not needed, greatly decreasing LFTR fuel cost
• the reactor is much cleaner: as a full recycle system, the discharge wastes from the reactor are predominately fission products, most of which have relatively short half lives compared to longer-lived actinide wastes.^[18] This results in a significant reduction in the needed waste containment period in a geologic repository to reach safe radiation levels (300 years vs. tens of thousands of years)
• it can "burn" problematic radioactive waste with transuranic elements from traditional solid-fuel nuclear reactors, thus solve the High level waste problem by turning liability into an asset
• it is highly scalable. Small, 2–8 MW(thermal) or 1–3 MW(electric) versions are possible, enabling submarine or aircraft use
• LFTR would have no refueling power outages due to continual refueling
• it can react to load changes in less than 60 seconds (unlike "traditional" solid-fuel nuclear power plants), thus it can satisfy both base load and peak load power demands
• with a very high temperature reactor such as LFTR, it is possible to use very efficient Brayton cycle generating turbines.^[11] The thermal efficiency from the high temperature of its operation reduces fuel use, waste emission and the cost of auxiliary equipment (major capital expenses) by 50% or more
• since the core is not pressurised, it does not need the most expensive item in a light water reactor, a high-pressure reactor vessel for the core. Instead, there is a low-pressure vessel and pipes (for molten salt) constructed of relatively thin materials. Although the metal is an exotic nickel alloy that resists heat and corrosion, Hastelloy-N, the amount needed is relatively small and the thin metal is less expensive to form and weld.
• by using liquid salt as the coolant instead of presurised water a containment structure only slightly bigger than the reactor vessel can be used. Light water reactors use pressurised water which flashes to steam and expands a thousandfold in the case of a leak, necessitating a containment building a thousandfold bigger in volume than the reactor vessel. This gives the LFTR a substantial theoretical advantage in terms of lower construction cost.
• it can be air-cooled, which is critical for use in many regions where water is scarce
• fission products of a LFTR include stable rare elements such as rhodium, ruthenium, technetium, cesium and xenon, which are relied heavily on in modern electronics and industrial processes. These can be extracted from the waste. Medically valuable isotopes are also among LFTR fission products

Kirk Sorensen expects that with these advantages, LFTR technology will produce energy significantly cheaper than coal; he comments that this would make moot both carbon pricing schemes and more expensive alternative energy solutions^[20] In remarks prepared for the Low-Carbon Energy Summit on 20 October 2011, Sorensen stated that "The most important thing that we can do to fight climate change is to replace coal as our primary source of electricity" and advocated the LFTR as an "even less expensive" replacement.^[21] The ultimate goal is to "provide electricity for less cost than any other competing solution" which Sorensen thinks will "eventually get to 1 cent per kilowatt hour using this technology"^[22][23]

Ease of reprocessing

A molten salt reactor's fuel can be continuously reprocessed with a small adjacent chemical plant. Weinberg's groups at Oak Ridge National Laboratory found that a very small reprocessing facility can service a large 1 GW power plant: All the salt has to be reprocessed, but only every ten days. The reactor's total inventory of expensive, poisonous radioactive materials is therefore much smaller than in a conventional light-water-reactor's fuel cycle, which has to store spent fuel rod assemblies. Also, everything except fuel and waste stays inside the plant. The reprocessing cycle is:

• A sparge of fluorine removes volatile high-valence fluorides as gas, including uranium hexafluoride containing the uranium-233 fuel as well as other isotopes of uranium; neptunium hexafluoride; technetium hexafluoride and selenium hexafluoride containing the long-lived fission products technetium-99 and selenium-79, as well as fluorides of various strongly radioactive short-lived fission products such as iodine-131, molybdenum-99, and tellurium-132. See fluoride volatility for boiling points. The volatile fluorides are condensed from the sparge fluorine, reduced back to less volatile lower-valence fluorides, and returned to the reactor.
• A molten bismuth column separates protactinium from the fuel salt, which is stored to allow protactinium-233 to decay to uranium-233 without being destroyed by neutron capture in the reactor. With a half-life of 27 days, ten months of storage assures that 99.9% of ²³³Pa decays to ²³³U fuel, while any ²³¹Pa remains in the bismuth.
• The remaining fuel salt is then distilled at increased temperature and lowered pressure. The distillate is condensed and returned to the reactor.
  • The light carrier salts beryllium fluoride and lithium fluoride form the bulk of the salt; individually at atmospheric pressure they evaporate at 1169 °C and 1676 °C, while the 2:1 FLiBe mixture with proportions Li₂BeF₄ evaporates at 1430 °C. Boiling points under vacuum are lower.
  • Cesium fluoride, containing the most radioactive medium-lived fission product cesium-137, boils at 1251 °C under standard conditions, and will evaporate with the carrier salt fluorides.
  • Thorium(IV) fluoride evaporates at temperatures about 1680 °C or less under vacuum.
  • Lanthanide trifluorides and alkaline earth fluorides have boiling points higher than 2200 °C under standard conditions, and would remain after thorium fluoride evaporates; the lanthanides include the worst long-term neutron poisons, while strontium fluoride contains the other major medium-lived fission product strontium-90.

The amount of waste involved is about 800 kg per gigawatt-year generated (1.5 grams/minute for a 1 GW reactor), so the equipment is very small. Salts of long-lived transuranic metals go back into the reactor as fuel. With salt distillation, an MSFR can burn plutonium, or even fluorinated nuclear waste from light water reactors.

• Theoretically, a "two-fluid" reactor design could separate the fertile thorium from the fissile fuel salts. This would eliminate the technologically challenging separation of thorium fluoride (boiling point 1680 °C) and lanthanide fission product fluorides via high-temperature distillation, at the cost of a more complex reactor. Oak Ridge researchers abandoned two-fluid designs because no good pipe materials were known to operate in the high-temperature, high-neutron, corrosive environment of a MSR core.^[24]

Disadvantages

• There have been only limited studies on Molten salt reactors including LFTRs so far. As such it is difficult to critically asses the concept.^[25]
• The proposed salt mixture FLiBe, has large amounts of beryllium, a poisonous element. The salt in the primary and secondary cooling loops must be isolated from workers and the environment to protect from beryllium poisoning.
• Hot fluoride salts naturally produce hydrofluoric acid when in contact with water. When cool, fluoride salts are nearly insoluble in water. Although HF generation would be taken into consideration in the reactor's design and shutdown/decommission processes, this hazard needs to be addressed in emergency situations that damage all five levels of the reactor's containment while the salt is hot.

Design challenges

• High neutron fluxes and temperatures in a compact MSR core can change the shape of a graphite moderator element, causing it initially to shrink, then expand. The 1960 two-fluid design had an estimated graphite replacement period of four years.^[26](p3) Eliminating graphite from sealed piping was a major incentive to switch to a single-fluid design.^[24] Most MSR designs do not use graphite as a structural material, and arrange for it to be easy to replace. At least one design used graphite balls floating in salt, which could be removed and inspected continuously without shutting down the reactor.^[27] Reducing the power density of the reactor design increases graphite lifetime.^[28](p10)

• Corrosion is significant if the reactor is exposed to any isotope of hydrogen, which forms corrosive, chemically reactive, radioactive hydrogen fluoride (HF) gas. The high neutron density in the core rapidly transmutes lithium-6 to tritium, a radioactive isotope of hydrogen, which is nearly identical, chemically speaking. In hot fluoride salts, the tritium forms tritium fluoride. Because of this, if a MSR design uses a lithium salt, it uses the lithium-7 isotope in order to prevent tritium formation. In the MSRE, Tritium formation was prevented by the removal of lithium-6 from the fuel salt via isotopic enrichment. Since lithium-7 is at least 16% heavier than lithium-6, and is the most common isotope of lithium, the lithium-6 is comparatively easy and inexpensive to extract from naturally occurring lithium. Vacuum distillation of lithium achieves efficiencies of up to 8% per stage and only requires heating of raw lithium in a vacuum chamber. The aforementioned method worked in preventing hydrogen corrosion in the MSRE.^[29] Practical MSRs also operate the salt under a blanket of dry inert gas, usually helium.

• The reactor makes small amounts of Tellurium as a fission product. In the MSRE, this caused small amounts of corrosion at the grain boundaries of the special Nickel alloy, Hastelloy-N used for the reactor. Metallurgical studies showed that adding 1 to 2% Niobium to the Hastelloy-N alloy was found to offer improved resistance to corrosion by Tellurium.^{[14](pp81-87)} One additional strategy against corrosion was to keep the fuel salt slightly reducing by maintaining the ratio of UF₄/UF₃ to less than 60.^[30](pp3-4)

• If the Fluoride fuel salts are stored in solid form over many decades, radiation can cause the release of corrosive Fluorine gas, and Uranium hexafluoride.^[31] The salts should be defueled and wastes removed before extended shutdowns. Fluoride containing wastes could go through a vitrification process to be encased in borosilicate glass suitable for long-term disposal.^[32]

Recent developments

The Fuji MSR

The FUJI MSR is a 100 to 200 MWe molten-salt-fueled thorium fuel cycle thermal breeder reactor design, using technology similar to the Oak Ridge National Laboratory Reactor. It is being developed by a consortium including members from Japan, the U.S. and Russia. As a breeder reactor, it converts thorium into nuclear fuels.^[33] As a thermal-spectrum reactor, its neutron regulation is inherently safe. Like all molten salt reactors, its core is chemically inert, under low pressures to prevent explosions and toxic releases.^[34] It would likely take 20 years to develop a full size reactor^[35] but the project seems to lack funding.^[36]

Chinese Thorium MSR project

The People’s Republic of China has initiated a research and development project in thorium molten-salt reactor technology.^[37] It was formally announced at the Chinese Academy of Sciences (CAS) annual conference in January 2011. Its ultimate target is to investigate and develop a thorium based molten salt nuclear system in about 20 years.^[38][39][40]

Flibe Energy

Kirk Sorensen, former NASA scientist and Chief Nuclear Technologist at Teledyne Brown Engineering, has been a long time promoter of thorium fuel cycle and particularly liquid fluoride thorium reactors. He first researched thorium reactors while working at NASA, while evaluating power plant designs suitable for lunar colonies. Material about this fuel cycle was surprisingly hard to find, so in 2006 Sorensen started "energyfromthorium.com", a document repository, forum, and blog to promote this technology. In 2011, Sorensen founded Flibe Energy, a company aimed to develop 20-50 MW LFTR reactor designs to power military bases. (it is easier to approve novel military designs than civilian power station designs in today's US nuclear regulatory environment).^{[41][42][43][44]}

Small modular design

Kirk Sorensen of Flibe Energy, presenting at the 2011 Thorium Energy Conference, described how various factors influence design for small modular reactors.^[45]

Neutron temperature requirements matter on two fronts. Primarily is fuel choice:

• U-235 and Th-232/U-233 work most efficiently with thermal spectrum neutrons (<1 eV)
• U-238/Pu-239 requires fast spectrum neutrons (>100,000 eV) to sustain breeding

Second is the amount of fissile material needed in the reactor. Fast spectrum neutrons deal with a much smaller nuclear cross section, meaning that for any given distance, they are less likely to be absorbed by a fissile or breedable nucleus than thermal spectrum neutrons. This drives up the minimum fissile inventory for a given power level.

Operating Temperature has two basic ranges. "Moderate" is defined as 250-350 C, and is comparable to conventional Light Water Reactor and fossil plant temperature ranges. "High" is defined as 700-1000 C, which provides greater efficiency due to the higher temperature gradient with ambient, but provides challenges for material selection.

Operating Pressure can be anywhere between "Atmospheric" and "High" pressure (15.5 MPa (153 atm) for a Pressurized water reactor is considered high). These ranges are related to coolant type.

Here are four examples among the proposed small modular reactor designs, one for each temperature/pressure combination:

• Water: Moderate Temperature, High Pressure (e.g. B&W mPower, NuScale, Westinghouse,^[46][47] IRIS, KLT-40)
• Gas: High Temperature, High Pressure (e.g. Pebble bed modular reactor, Gas turbine modular helium reactor, Energy Multiplier Module)
• Liquid Metal: Moderate Temperature, Atmospheric Pressure (e.g. Hyperion, Toshiba 4S, GE PRISM)
• Molten salt reactor: High Temperature, Atmospheric Pressure (e.g. LFTR)

Various conclusions about the three fuels and possible reactor types are then drawn:

Higher temperature reactors can operate at higher thermal efficiency (e.g. with Brayton cycle turbines), which is desirable. High turbine pressure is a safety concern, as the proposed turbines - using Supercritical carbon dioxide - would need to operate at over 20 MPa (195 atm). The safety concern is more industrial than radiological, however, as turbine systems are generally not built close enough to their heat generators to be a risk to them.

The main drawback of U-235 is its scarcity. Even so, most currently operating reactors use it in water-cooled reactors. Gas-based concepts (e.g. PBMR, VHTR, GT-MHR) are also feasible.

The liquid metal coolants used are poor neutron moderators, thus such systems strongly favor U-238/Pu-239 usage; adding moderators to enable use with U-235 or Th-232/U-233 would be "feasible but unattractive". Conversely, water is a good moderator and this rules out exclusive plutonium breeding in such systems. Gas-cooled systems with U-238/Pu-239 (Gas Cooled Fast Breeder Reactor (GCFR) and EM2 concepts) are described as feasible but with difficult fuel processing, while molten salt systems with U-238/Pu-239 (e.g. MSFR) are only "somewhat feasible."

Sorensen notes that while Th-232/U-233 was used in a water-cooled reactor at the Shippingport Atomic Power Station and a gas-cooled reactor at the Fort St. Vrain Generating Station, thorium dioxide fuel is "very difficult to process," making Th-232/U-233 unattractive for all systems except liquid salt, e.g. where thorium and uranium fluorides are used instead.

In Sorenson's opinion, the LFTR design combines the desirable characteristics of abundant fuel supply, high operating temperature, atmospheric operating pressure and simple fuel processing.

The Weinberg Foundation

The Weinberg Foundation is a British non-profit organisation founded in 2011 dedicated to promotion and development of a liquid fluoride thorium reactor. It was formally launched at the House of Lords on 8 September 2011.^[48][49][50]

See also

• Generation IV reactor
• Molten salt reactor
• Thorium fuel cycle

Proponents

• James Hansen
• Kirk Sorensen
• Stephen Tindale
• Bryony Worthington

References

Further reading

• Dr. Robert Hargraves (2009). Aim High!: Thorium energy cheaper than from coal solves more than just global warming. BookSurge Publishing. ISBN 1439225389. 

Available here in pdf

External links

• EnergyFromThorium.com - Blog / Website about LFTR with document repository and discussion forum
• Thorium Energy Alliance - advocacy and educational organisation dedicated to thorium energy
• Third Thorium Energy Alliance Conference - TEAC3
• International Thorium Energy Organisation
• ThoriumMSR.com - a comprehensive website and blog about thorium molten salt reactor technology
• Weinberg Foundation website
• Flibe Energy company website
• Thorium and LFTR Top Ten Attributes (a talking points memorandum by Flibe Energy)

Videos:

• Google TechTalks – Liquid Fluoride Thorium Reactor: What Fusion Wanted To Be by Dr. Joe Bonometti NASA / Naval Post Graduate School
• Kirk Sorensen discuss "Thorium" at TEDxYYC 2011
• "Thorium Remix 2011" - a video describing the thorium fuel cycle and LFTR
• An overview of the proposed LFTR power plant design by Thorium Energy Alliance
• Motherboard TV: The Thorium Dream documentary
• Potential of Thorium Fueled Molten Salt Reactors - presentation by Dr. David LeBlanc at TEAC3 Conference
• Dr. Robert Hargraves: Aim High! - Thorium Energy Cheaper Than From Coal presented at TEAC3 Conference
• James Kennedy - "U.S. Heavy Rare Earth Cooperative, the Global Economics of Thorium Energy" presented at TEAC3 Conference
• Google TechTalks – The Thorium Molten-Salt Reactor: Why Didn't This Happen - A presentation examining the history of thorium molten salt reactor development at Oak Ridge and political climate and reasons responsible for the cancellation of the program

Media articles:

• The Telegraph: Obama could kill fossil fuels overnight with a nuclear dash for thorium
• The Telegraph: Safe nuclear does exist, and China is leading the way with thorium
• C&EN News: Reintroducing Thorium
• Mechanical Engineering: Too Good to Leave on the Shelf
• Russia Today: Scientists hail metal thorium as alternative source of energy
• American Scientist: Liquid Fluoride Thorium Reactors
• Forbes: Is Thorium the Biggest Energy Breakthrough Since Fire? Possibly.
• Wired: Uranium Is So Last Century — Enter Thorium, the New Green Nuke
• The Guardian: Why thorium nuclear power shouldn't be written off
• The Guardian: China enters race to develop nuclear energy from thorium
• CNN: Thorium: World's greatest energy breakthrough?
• COSMOS: New age nuclear
• The Week: Could thorium make nuclear power safe?
• The Independent: Is thorium the answer to our energy crisis?
• Popsci: Development of Tiny Thorium Reactors Could Wean the World Off Oil In Just Five Years
• Financial Times: New life for forgotten fuel
• Australian Mining: Australian and Czech consortium announce thorium joint venture

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