If 232 Th is loaded in the nuclear reactor, the nuclei of 232 Th absorb a neutron and become nuclei of 233 Th. Update: See our full page on Molten Salt Reactors for more info. Chris Coles December 29, 2020 02:56 AM. Although thorium advocates say that thorium reactors produce little radioactive waste, they simply produce a different spectrum of waste to those from uranium-235. neutrons, it will undergo a series of nuclear reactions until it eventually emerges as an isotope of The nuclear industry is quite conservative, Thorium cycles exclusively allow thermal breeder reactors (asopposed to fast breeders). stealing spent fuel are largely reduced by Th, but the possibility of the owner of a Th-U reactor But Molten salt reactors are amazing. This is irrelevant for fluid-fueled reactors discussed below. Pa-233 is a pretty strong neutron absorber, so the MSBR (basically the LFTR) has to extract it from the core once it is produced and let it … Naturally, it takes some time for enough uranium-233 to accumulate to make this particular fission process spontaneously ongoing. high-quality solid fuel. Uranium 232 has a half-life of 68.9 years, and its daughter radionuclides emit intense, highly penetrating gamma rays that make the material difficult to handle. One-millionth of a gram of plutonium, if inhaled, is carcinogenic.). And because of the complexity of problems listed below, thorium reactors are far more expensive than uranium fueled reactors. The Th-U fuel cycle has some intriguing capabilities over the traditional U-Pu cycle. Four commercial thorium reactors were constructed, all of which failed. Thorium exists in nature in a single isotopic form – T… In these, fuel is not cast into pellets, but is rather It competed with the liquid metal cooled fast breeder reactors IN2P3 Uranium-233 has an extremely long half-life of 159,000 years, but too short for be still present on Earth. More neutrons are released per neutronabsorbed in the fuel in a traditional (thermal) type of reactor It is reprocessed, reactors could be fueled without mining any additional Reduced nuclear waste. Reprocessing spent fuel requires chopping up radioactive fuel rods by remote control, then dissolving them in concentrated nitric acid from which plutonium is precipitated out by complex chemical means. gammas to come back. It is estimated that it will take over one million dollars per kilogram to dispose of the seriously deadly material. By Also, thorium’s small nuclear waste only has a half-life of 300 years, not 10,000 years. (Just kidding, there are It is estimated to be about four times more abundant than uranium in the Earth’s crust. well as in summary below. Soil contains an average of around 6 parts per million (ppm) of thorium. Thorium fuel is a bit harder to prepare. plutonium is that it can be chemically separated from the waste and perhaps used in bombs. U-233 is Th-232 -> Th-233 -> Pa-233 -> U-233). It takes about the same amount of uranium-233 as plutonium-239 – six kilos – to fuel a nuclear weapon. Of course, it The DOE Office of Environmental Management now considers the disposal of this uranium-233 to be ‘an unfunded mandate’. As Australia is grappling with the notion of introducing nuclear power into the country, it seems imperative the general public understand the intricacies of these technologies so they can make informed decisions. All of these isotopes are unstable (radioactive), but only 232 Th is relatively stable with half-life of 14 billion years, which is comparable to the age of the Earth (~4.5×10 9 years). This means that the contaminants could be chemically separated and the material Instead of thorium, a Molten Salt Reactor can use uranium-235 or plutonium waste, from LWR and other reactors. and the biggest problem with Thorium is that we are lacking in operational experience with it. These gamma rays are very hard to shield, requiring more expensive is the molten salt reactor (MSR), or as one particular MSR is commonly known on the internet, the One of the biggest is that a much higher fuel burn-up reduces plutonium waste by more than 80%. However, contrary to proponent’s claims The thorium-based fuel also comes with other key benefits. This waste fuel is highly radioactive and the culprits – these high-mass isotopes – have half-lives of many thousands of years. 4 And with today’s reactor designs, which in the U.S. are fairly outdated, small disruptions in the process can also lead to catastrophic overheating and meltdowns. Let us start with the basic nuclear properties of Thorium, which present some problems for a reactor designer. Thorium As Nuclear Fuel: the good and the bad, Computing the energy density of nuclear fuel, Molten Salt Reactor Experiment Half a century ago, Oak Ridge National Lab in Tennessee successfully ran an experimental reactor that demonstrated feasibility. This means that if the fuel is to shut down for fuel management, etc.). successfully tested. What about a thorium reactor design?? processing removes fission product neutron poisons and allows online refueling (eliminating the need through a heat exchanger to bring the heat out to a turbine and make electricity. They can actually burn up more radioactive waste than they produce. Although thorium advocates say that thorium reactors produce little radioactive waste , they simply produce a different spectrum of waste to those from uranium-235, which includes many dangerous alpha and beta emitters and isotopes with extremely long half-lives including technetium 99 - half-life of Thorium-fueled reactors, on the other hand, are fuel-efficient, almost perfectly so, but that comes at the end of a three-phase process, with the first phase shared by thorium … Normally, Pa is passed into the fission product waste in the THOREX process, which could have long term … Thorium is very insoluble, which is why it is plentiful in sands but not in seawater, in contrast to uranium. Compared to uranium reactors, thorium reactors produce far less waste, and the waste is much less radioactive with a much shorter half-life. MSR reactors can be an effective way of getting rid of highly radioactive waste. Exotic, but These reactors could absorbed in the fuel in a traditional (thermal) type of reactor. Thus, the quantity of U-233 does not change and abundant thorium is consumed in what is called the thorium fuel cycle. be extremely safe, proliferation resistant, resource efficient, environmentally superior (to best suited for Molten Salt Reactors, which are discussed on their own page as Also, the This still includes many dangerous alpha and beta emitters, and isotopes with extremely long half-lives, including iodine-129 (half-life of 15.7 million years). Thorium reactors also produce uranium-232, which decays to an extremely potent high-energy gamma emitter that can penetrate through one metre of concrete, making the handling of this spent nuclear fuel extraordinarily dangerous. avoiding plutonium altogether, thorium cycles are superior in this regard. It takes almost a year after the reactor shutdown for all of the protactinium-233 to transform into uranium-233. invariably produces some U-232, which decays to Tl-208, which has a 2.6 MeV gamma ray decay mode. [wikipedia] (MSRE). In the thorium cycle, fuel is formed when Th captures a neutron (whether in a fast reactor or thermal reactor) to become Th . Finally, unlike U235, thorium is an efficient neutron absorber and producer. Note, however, that the gammas come from the decay chain of U-232, not The longstanding effort to produce these reactors cost the U.S. taxpayers billions of dollars, while billions more dollars are still required to dispose of the highly toxic waste emanating from these failed trials. Hype alert   If someone on the internet told you something unbelievable about Thorium, you might want to check out our Thorium Myths page just to double check it. All of the remaining thorium isotopes have half-lives that are less than thirty days and the majority of these have half-lives that are less than ten minutes. Deploying new uranium-based nuclear reactors would likely happen much more rapidly and at a substantially lower cost. challenging route, one could obtain weapons material. Can Consume Nuclear Waste. heat from these gammas makes weapon fabrication difficult, as it is hard to keep the weapon pit from While U-233 an excellent fuel in other things). The Th-U fuel cycle does not irradiate Uranium-238 and therefore does not produce transuranic Plutonium has a shorter half-life of about 24,000 years compared to Uranium-235's half-life … Thorium-232 is useful in breeder reactors because on capturing slow-moving neutrons it decays into fissionable uranium-233. One especially cool possibility suitable for the thermal-breeding capability of the Th-U fuel cycle test reactor of this type in the 1960s called the Molten Salt Reactor Experiment This still includes many dangerous alpha and beta emitters, and isotopes with extremely long half-lives, including iodine-129 (half-life of 15.7 million years). Yes. The spent U-235 from the reactor contains very radioactive isotopes with a half-life of thousands of years, so the waste has to be stored safely for up to 10,000 years. The half-life of 233 Th is approximately 21.8 minutes. Isotope 232 Th belongs to primordial nuclides and … Who’s going to start the startup on these? Plutonium has a shorter half-life of about 24,000 years compared to Uranium-235's half-life of just over 700 million years. We don’t have as much experience with Th. Besides avoiding plutonium, Thorium has additional self-protection from the hard gamma rays emitted DR. High-level radioactive waste primarily is uranium fuel that has been used in a nuclear power reactor and is "spent," or no longer efficient in producing electricity. The half-life of thorium-234 is only 24 days. year time scale. to be used to fuel a nuclear chain reaction that can run a power plant and make electricity (among spent fuel handling and/or reprocessing. Reprocessing, as conducted at La Hague in France, involves exposing workers to toxic radioisotopes and still produces high volumes of radioactive waste. For more information, see the Beyond Nuclear thorium fact sheet. Online chemical These transuranics are the So there is an extraordinarily complex, dangerous and expensive preliminary process to kick-start a fission process in a thorium reactor. (bigger than uranium) atoms like Plutonium, Americium, Curium, etc. Nuclear reactor fuel contains ceramic pellets of uranium-235 inside of metal rods. Liquid Fluoride Thorium Reactors (LFTR). This normally emits an electron and an anti-neutrino ( ν ) by β decay to become Pa . opposed to fast breeders). An Energy Department safety investigation recently found a national repository for uranium-233 in a building constructed in 1943 at the Oak Ridge National Laboratory. The MSRE successfully proved that the concept has merit and can be operated Thorium has 6 naturally occurring isotopes. When money is at stake, it’s difficult to get people to change from the norm. Additionally, Th is quite inert, making it difficult to chemically process. In order to overcome the initial lack of fissile nuclei in a thorium fuel one may add fissile plutonium to this thorium. More neutrons are released per neutron (U-235) or reprocessed plutonium (Pu-239) as fuel (in the Uranium-Plutonium cycle), and only a In deep seawaters the isotope 230 Th makes up to 0.04% of natural thorium. traditional nukes, as well as to fossil fuel obviously), and maybe even cheap. Thorium advocates say that thorium reactors produce little radioactive waste, however, they simply produce a different spectrum of waste from traditional reactors, including many dangerous isotopes with extremely long half-lives. ... and with a half-life of over 24,000 years, it's tricky to store and dispose of. It was in poor condition. Investigators reported an environmental release from many of the 1,100 containers could ‘… be expected to occur within the next five years because some of the packages are approaching 30 years of age and have not been regularly inspected.’, The DOE determined that this building had “Deteriorated beyond cost-effective repair and significant annual costs would be incurred to satisfy both current DOE storage standards, and to provide continued protection against potential nuclear criticality accidents or theft of the material.”. This is because its parent 238 U is soluble in water, but 230 Th is insoluble and precipitates into the sediment. • In the conversion chain of 232Th to 233U, 233Pa is formed as an intermediate, which has a relatively longer half-life (~27 days) as compared to 239Np (2.35 days) in the uranium fuel cycle thereby requiring longer cooling time of at least one year for completing the decay of 233Pa to 233U. So concerns over people Thorium itself will not split and release energy. already like 4 startups working on them, and China is developing them as well). Synthetic isotopes have been prepared; thorium-229 (7,880-year half-life), formed in the decay chain originating in the synthetic actinoid element neptunium, serves as a tracer for ordinary thorium (thorium-232). Thorium is therefore called fertile, whereas U-233 is called fissile. During the fission process, two things happen to the uraniu… In other words, the thorium nucleus is very stable, with an extremely long shelf-life. Later, the radioactive fuel would be removed from the reactor and reprocessed to separate out the uranium-233 from the contaminating fission products, and the uranium-233 will then be mixed with more thorium to be placed in another thorium reactor. After absorbing a neutron, thorium-232 is transmuted into thorium-233, which then beta-decays with a half-life of 22 minutes into protactinium-233, which is chemically distinct from the parent thorium. Thorium reactors are amongst those being suggested at this time. Then, it will decay directly to pure U-233. in the not-too-distant future…. One of the biggest is that a much higher fuel burn-up reduces plutonium waste by more than 80%. None of these reactors operate today, but Oak Ridge had a major health concern of long-term nuclear waste. 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. Bi-212 also causes problems. (Fast-spectrum molten salt reactors (FS-MSR) can use all isotopes of uranium, not just the 0.7% U-235 in natural uranium — with all the safety and stability of MSR.) Alvin Weinberg discusses the history of this project in The truth is, thorium is not a naturally fissionable material. melting due to its own heat. In nature, virtually all thorium is thorium-232, and has a half-life of about 14.05 billion years. That means no matter how many thorium nuclei are packed together, they can not go critical. Half-life of 233 Pa. Thorium 232 is “only” a fertile material and the main problem can be directly in the breeding of fissile uranium 233. The half-life of thorium 232, its most abundant isotope, is 14 billion years, or about as old as the universe. Although thorium advocates say that thorium reactors produce little radioactive waste, they simply produce a spectrum of waste that’s different from those from uranium 235, which includes many dangerous alpha and beta emitters and isotopes with extremely long half-lives, including technetium 99, with a half-life of 300,000 years, and iodine 129, with a half-life of 15.7 million years. The problem with the thermal spectrum, it is between U-235 and Pu-239 in the fast spectrum. (Photo: Jean-Marie Taillat for WikiMedia Commons), Vast quantities of highly acidic, highly radioactive liquid waste then remain to be disposed of. (Only 6 kilograms of plutonium-239 can fuel a nuclear weapon, while each reactor makes 250 kilos of plutonium per year. Pingback: The delusion of thorium — Beyond Nuclear International « nuclear-news, Pingback: The delusion of thorium — Beyond Nuclear International « Antinuclear, The delusion of thorium — Beyond Nuclear International « nuclear-news, The delusion of thorium — Beyond Nuclear International « Antinuclear. The chain reaction heats the salt, which naturally convects much detail in his autobiography, The First Nuclear That still means hundreds of years of waste. Thorium doesn’t work as well as U-Pu in a fast reactor. obtaining bomb material is not. Current uranium waste is 30,000 tons per year. Like Uranium, its properties allow it Current and exotic designs can theoretically accommodate thorium.