Where Can I Buy Thorium
The use of thorium as a new primary energy source has been a tantalizing prospect for many years. Extracting its latent energy value in a cost-effective manner remains a challenge, and will require considerable R&D investment. This is occurring preeminently in China, with modest US support.
where can i buy thorium
Thorium is a naturally-occurring, slightly radioactive metal discovered in 1828 by the Swedish chemist Jons Jakob Berzelius, who named it after Thor, the Norse god of thunder. It is found in small amounts in most rocks and soils, where it is about three times more abundant than uranium. Soil contains an average of around 6 parts per million (ppm) of thorium. Thorium is very insoluble, which is why it is plentiful in sands but not in seawater, in contrast to uranium.
When pure, thorium is a silvery white metal that retains its lustre for several months. However, when it is contaminated with the oxide, thorium slowly tarnishes in air, becoming grey and eventually black. When heated in air, thorium metal ignites and burns brilliantly with a white light. Thorium oxide (ThO2), also called thoria, has one of the highest melting points of all oxides (3300C) and so it has found applications in light bulb elements, lantern mantles, arc-light lamps, welding electrodes and heat-resistant ceramics. Glass containing thorium oxide has both a high refractive index and wavelength dispersion, and is used in high quality lenses for cameras and scientific instruments.
The most common source of thorium is the rare earth phosphate mineral, monazite, which contains up to about 12% thorium phosphate, but 6-7% on average. Monazite is found in igneous and other rocks but the richest concentrations are in placer deposits, concentrated by wave and current action with other heavy minerals. World monazite resources are estimated to be about 16 million tonnes, 12 Mt of which are in heavy mineral sands deposits on the south and east coasts of India. There are substantial deposits in several other countries (see Table below). Thorium recovery from monazite usually involves leaching with sodium hydroxide at 140C followed by a complex process to precipitate pure ThO2. Thorite (ThSiO4) is another common thorium mineral. A large vein deposit of thorium and rare earth metals is in Idaho.
The International Atomic Energy Agency (IAEA) and the OECD Nuclear Energy Agency (NEA) joint publication Uranium 2016: Resources, Production and Demand (often referred to as the Red Book) gives a figure of 6.2 million tonnes of total known and estimated resources (the 2018 edition of the same publication did not provide estimates of thorium resources). Data for reasonably assured and inferred resources recoverable at a cost of $80/kg Th or less are given in the table below, excluding some less-certain Asian figures. Some of the figures are based on assumptions and surrogate data for mineral sands (monazite x assumed Th content), not direct geological data in the same way as most mineral resources.
In fresh thorium fuel, all of the fissions (thus power and neutrons) derive from the driver component. As the fuel operates the U-233 content gradually increases and it contributes more and more to the power output of the fuel. The ultimate energy output from U-233 (and hence indirectly thorium) depends on numerous fuel design parameters, including: fuel burn-up attained, fuel arrangement, neutron energy spectrum and neutron flux (affecting the intermediate product protactinium-233, which is a neutron absorber). The fission of a U-233 nucleus releases about the same amount of energy (200 MeV) as that of U-235.
Th-232 is fissionable with fast neutrons of over 1 MeV energy. It could therefore be used in fast molten salt and other Gen IV reactors with uranium or plutonium fuel to initiate fission. However, Th-232 fast fissions only one tenth as well as U-238, so there is no particular reason for using thorium in fast reactors, given the huge amount of depleted uranium awaiting use.
In Norway, Thor Energy is developing and testing a thorium-bearing fuel for use in existing nuclear power plants. Fuel rods containing thorium additive (Th-Add) and also thorium MOX (with Pu) fuel rods were tested in a five-year irradiation trial that started in April 2013 at the Halden test reactor. The company is working towards obtaining regulatory approval for the commercial production and use of Th-Add fuel. In February 2018 a third batch of Th-MOX fuel pellets commenced testing. This fuel is promoted as a means to improve power profiles within commercial reactors.
There are seven types of reactor into which thorium can be introduced as a nuclear fuel. The first five of these have all entered into operational service at some point. The last two are still conceptual:
Heavy Water Reactors (PHWRs): These are well suited for thorium fuels due to their combination of: (i) excellent neutron economy (their low parasitic neutron absorption means more neutrons can be absorbed by thorium to produce useful U-233), (ii) slightly faster average neutron energy which favours conversion to U-233, (iii) flexible on-line refueling capability. Furthermore, heavy water reactors (especially CANDU) are well established and widely-deployed commercial technology for which there is extensive licensing experience.
There is potential application to Enhanced Candu 6 (EC6) and ACR-1000 reactors fueled with 5% plutonium (reactor grade) plus thorium. In the closed fuel cycle, the driver fuel required for starting off is progressively replaced with recycled U-233, so that on reaching equilibrium 80% of the energy comes from thorium. Fissile drive fuel could be LEU, plutonium, or recycled uranium from LWR. Fleets of PHWRs with near-self-sufficient equilibrium thorium fuel cycles could be supported by a few fast breeder reactors to provide plutonium.
Pressurised (Light) Water Reactors (PWRs): Viable thorium fuels can be designed for a PWR, though with less flexibility than for BWRs. Fuel needs to be in heterogeneous arrangements in order to achieve satisfactory fuel burn-up. It is not possible to design viable thorium-based PWR fuels that convert significant amounts of U-233. Even though PWRs are not the perfect reactor in which to use thorium, they are the industry workhorse and there is a lot of PWR licensing experience. They are a viable early-entry thorium platform.
Molten Salt Reactors (MSRs): These reactors are still at the design stage but are likely to be very well suited for using thorium as a fuel. The unique fluid fuel can incorporate thorium and uranium (U-233 and/or U-235) fluorides as part of a salt mixture that melts in the range 400-700ºC, and this liquid serves as both heat transfer fluid and the matrix for the fissioning fuel. The fluid circulates through a core region and then through a chemical processing circuit that removes various fission products (poisons) and/or the valuable U-233. The level of moderation is given by the amount of graphite built into the core. Certain MSR designsc will be designed specifically for thorium fuels to produce useful amounts of U-233.
With regard to proliferation significance, thorium-based power reactor fuels would be a poor source for fissile material usable in the illicit manufacture of an explosive device. U-233 contained in spent thorium fuel contains U-232 which decays to produce very radioactive daughter nuclides and these create a strong gamma radiation field. This confers proliferation resistance by creating significant handling problems and by greatly boosting the detectability (traceability) and ability to safeguard this material.
The 300 MWe Thorium High Temperature Reactor (THTR) at Hamm-Uentrop in Germany operated with thorium-HEU fuel between 1983 and 1989, when it was shut down due to technical problems. Over half of its 674,000 pebbles contained Th-HEU fuel particles (the rest comprised graphite moderator and some neutron absorbers). These were continuously moved through the reactor as it operated, and on average each fuel pebble passed six times through the core.
The 40 MWe Peach Bottom HTR in the USA was a demonstration thorium-fuelled reactor that ran from 1967-74.2 It used a thorium-HEU fuel in the form of microspheres of mixed thorium-uranium carbide coated with pyrolytic carbon. These were embedded in annular graphite segments (not pebbles). This reactor produced 33 billion kWh over 1349 equivalent full-power days with a capacity factor of 74%.
Research into the use of thorium as a nuclear fuel has been taking place for over 50 years, though with much less intensity than that for uranium or uranium-plutonium fuels. Basic development work has been conducted in Germany, India, Canada, Japan, China, Netherlands, Belgium, Norway, Russia, Brazil, the UK & the USA. Test irradiations have been conducted on a number of different thorium-based fuel forms.
Closed thorium fuel cycles have been designed4 in which PHWRs play a key role due to their fuelling flexibility: thoria-based HWR fuels can incorporate recycled U-233, residual plutonium and uranium from used LWR fuel, and also minor actinide components in waste-reduction strategies. In the closed cycle, the driver fuel required for starting off is progressively replaced with recycled U-233, so that an ever-increasing energy share in the fuel comes from the thorium component. AECL had a Thoria Roadmap R&D project.
For export, India has also designed an AHWR300-LEU which uses low-enriched uranium as well thorium in fuel, dispensing with plutonium input. About 39% of the power will come from thorium (via in situ conversion to U-233, c. two-thirds in AHWR), and burn-up will be 64 GWd/t. While closed fuel cycle is possible, this is not required or envisaged, and the used fuel, with about 8% fissile isotopes can be used in light water reactors. (See also information page on India).
High-temperature gas-cooled reactors: Thorium fuel was used in HTRs prior to the successful demonstration reactors described above. The UK operated the 20 MWth Dragon HTR from 1964 to 1973 for 741 full power days. Dragon was run as an OECD/Euratom cooperation project, involving Austria, Denmark, Sweden, Norway and Switzerland in addition to the UK. This reactor used thorium-HEU fuel elements in a 'breed and feed' mode in which the U-233 formed during operation replaced the consumption of U-235 at about the same rate. The fuel comprised small particles of uranium oxide (1 mm diameter) coated with silicon carbide and pyrolytic carbon which proved capable of maintaining a high degree of fission product containment at high temperatures and for high burn-ups. The particles were consolidated into 45mm long elements, which could be left in the reactor for about six years. 041b061a72