Thorium isotope 232. Thorium as a cure for nuclear plague

What happens if we say that the excess emissions of harmful substances resulting from the combustion of gasoline or conventional diesel fuel can be solved using a nuclear engine? Will it impress you? If not, then you don’t even have to start reading this material, but for those who are interested in this topic, you are welcome, because we will talk about an atomic engine for a car that runs on the thorium-232 isotope.

Surprisingly, it is thorium-232 that has the longest half-life among thorium isotopes and is also the most abundant. After reflecting on this fact, scientists from the American company Laser Power Systems announced the possibility of constructing an engine that uses thorium as a fuel and, at the same time, is an absolutely real project today.

It has long been determined that thorium, when used as a fuel, has a strong position and, when “working,” releases an enormous amount of energy. According to scientists, only 8 grams of thorium-232 will allow the engine to work for 100 years, and 1 gram will produce more energy than 28 thousand liters of gasoline. Agree, this can not fail to impress.

According to Charles Stevens, CEO of Laser Power Systems, the team has already begun experiments using small amounts of thorium, but the immediate goal is to create the laser needed for the process. Describing the principle of operation of such an engine, one can cite as an example the operation of a classical power plant. So, the laser, according to the plans of scientists, will heat a container with water, and the resulting steam will go to the work of mini-turbines.

However, no matter how breakthrough the statement of LPS specialists may seem, the very idea of using an atomic thorium engine is not new. In 2009, Lauren Culeusus showed the world community his vision of the future and demonstrated the Cadillac World Thorium Fuel Concept Car. And, despite its futuristic appearance, the main difference between the concept car was the presence of an energy source for autonomous operation, which used thorium as fuel.

“Scientists need to find a cheaper energy source than coal, with little or no carbon dioxide emissions when burned. Otherwise, this idea will not be able to develop at all ”- Robert Hargrave, a specialist in the field of studying the properties of thorium

At the moment, Laser Power Systems specialists are fully focused on creating a serial model of the engine for mass production. However, one of the most important questions does not disappear, how countries and companies lobbying for "oil" interests will react to such an innovation. Only time will tell the answer.

Interesting:

Natural reserves of thorium exceed those of uranium by 3-4 times
Experts call thorium and in particular thorium-232 "nuclear fuel of the future"

1 gram per 28,000 liters. This is the ratio of fuel consumption in automobile engines, if we replace the usual fuel with thorium.

We are talking about the 232nd isotope. It has the longest half-life. 8 grams of thorium is enough to run an engine continuously for 100 years.

There are 3 times more reserves of new fuel than in the earth's crust. Laser Power Systems specialists have already begun to develop a new engine.

American company. The operation of the engine will resemble the cycle of a standard power plant. The challenge was developing a suitable laser.

Its task is to heat water, the steam of which launches mini-turbines. While scientists are working out the process, we will learn more about the fuel of the 21st century, and in the future, the entire millennium.

What is thorium?

Thorium metal related to actinides. This family includes radioactive. All of them are located in the 3rd group of the 7th period of the table.

Actinide numbers are from 90 to 103. Thorium comes first. It was discovered first, simultaneously with uranium.

In its pure form, the hero was singled out in 1882 by Lars Nilsson. The radioactivity of the element was not immediately discovered.

So, thorium did not arouse public interest for a long time. Thorium decay proved only in 1907.

Since 1907 thorium isotopes opened one by one. By 2017, there are 30 metal modifications. 9 of them received.

The most stable is the 232nd. Thorium half life in this form lasts 1.4 * 10 10 years. That is why the 232nd isotope is ubiquitous, in the earth's crust it occupies a share of 8 * 10 -4%.

The remaining isotopes are stored for several years, and therefore are of no practical interest and are rarely found in nature. True, the 229th thorium decays in 7,340 years. But, this isotope is "derived" artificially.

Thorium has no completely stable isotopes. In its pure form, the element looks like -, plastic .

It is he who makes the mineral thorite so soft. easy to cut. The mineral was studied by Jens Berzenlius.

The Swedish chemist was able to calculate the unknown in the composition of the stone, but could not isolate it, giving the laurels to Nilson.

Thorium properties

Thorium is an element, whose specific radioactivity is 0.109 microcuries per gram. For uranium 238, for example, the figure is almost 3 times higher.

Accordingly, thorium is weakly radioactive. Several isotopes of thorium, by the way, are a consequence of the decay of uranium. We are talking about the 230th, 231st, 234th and 235th modifications of the 90th element.

The decay of the hero of the article is accompanied by the release of radon. This gas is also called thoron. However, the second name is not commonly used.

Radon is dangerous if inhaled. However, microdoses are contained in mineral waters and have a beneficial effect on the body.

It is the route of entry of thoron into the body that is important. You can drink, absorb - yes, but do not inhale.

In terms of the crystal lattice radioactive thorium appears in only two forms. Up to 1,400 degrees, the structure of the metal is face-centric.

It is based on three-dimensional cubes consisting of 14 atoms. Some of them are in the corners of the figure. The remaining atoms are located in the middle of each.

When heated above 1,400 degrees Celsius, the crystal lattice of thorium becomes body-centered.

The "packing" of such cubes is less dense. The already soft thorium becomes even more loose.

Thorium - chemical an element classified as paramagnetic. Accordingly, the magnetic permeability of the metal is minimal, close to unity.

The substances of the group are also distinguished by the ability to be magnetized in the direction of an external field.

The molar heat capacity of thorium is 27.3 kilojoules. The indicator indicates the thermal capacity of one mole of a substance, hence the name.

It is difficult to continue the list, since the bulk of the properties of the 90th metal depends on the degree of its contamination.

So, the tensile strength of the element varies from 150 to 290 meganewtons per square meter.

Thorium is also unstable. For metal, they give from 450 to 700 kilogram-force.

Standing at the beginning of its group, thorium took over some of the properties from the elements that preceded it. So, the hero of the article is characterized by the 4th degree of oxidation.

In order for thorium to quickly oxidize in air, you need to bring the temperature up to 400 degrees. The metal will instantly be covered with an oxide film.

The duet of thorium with oxygen, by the way, is the most refractory of terrestrial oxides, softens only at 3,200 degrees Celsius.

At the same time, the compound is also chemically stable. Pure metal reacts with

Any radioactive isotope of thorium interacts with it even at room temperature.

The remaining reactions with the hero of the article take place at elevated temperatures. At 200 degrees, there is a reaction with.

Powdered hydrides are formed. Nitrides are obtained when thorium is heated in the atmosphere.

A temperature of 800 degrees Celsius is required. But, first you need to get the reagent. Let's find out how they do it.

Mining and deposits of thorium

$350,000,000. Approximately the same amount is allocated annually for the development of thorium energy. There are a lot of deposits of the 232nd isotope in the country.

This is alarming, which risks losing its leadership in fuel if the 90th element becomes the main energy resource in the world.

There are reserves in the country. Millions of tons of metal, for example, are located near Novokuznetsk.

However, it is necessary to defend the priority right to use thorium, and for them the world is fighting. Everyone understands what the future is.

Usually, thorium is found in the form of shiny sand. This is the mineral monazite. The beaches from it are often included in the resort areas.

On the coast of the Sea of Azov, for example, it is worth considering not only solar radiation, but also that which comes from the earth. Veined thorium is found only in South Africa. The ore deposits there are called Steenkasmkraal.

If you extract thorium from ores, then it is easier to get an element along the way with. It remains to be seen where thorium could be useful, apart from the car engines of the future.

Application of thorium

Insofar as thorium nucleus unstable, natural use of the element in nuclear energy. For its needs, fluoride and thorium oxide are purchased.

Remember the temperature that the oxide of the 90th metal can withstand? Only such a compound will work in molten-salt reactors.

Thorium oxide also comes in handy in the aviation industry. There, the 90th metal serves as a hardener. The service of thorium is also in the body.

About 3 milligrams of a radioactive element comes in daily with food. It is involved in the regulation of system processes, absorbed mainly by the liver.

Thorium is also bought by metallurgists, but not for food. Pure metal is used as, that is, an additive that improves the quality, in particular, magnesium. With a ligature, they become heat-resistant and better resist tearing.

Finally, we will add information about the new car engine. The thorium in it is not nuclear fuel, but only the raw material for it.

By itself, the 90th element is not capable of providing energy. Everything is changed by the neutron environment and the water reactor.

With them, thorium is converted into uranium 233. Here it is - efficient fuel. How much do they pay for raw materials for it? Let's try to find out.

Thorium price

Thorium price differentiates into pure metal and its compounds. This is a common phrase from . Of the particulars - only the price tag per kilo of thorium oxide is about 7,500.

This concludes the open requests. Sellers are asked to clarify the cost, since they sell a radioactive element.

There are no offers of pure thorium on the Internet, just as there is no data on per gram of the metal. Meanwhile, those interested in a new type of automotive fuel are haunted by the question, just as they are haunted by whether the requests for the 90th element will jump in case of its widespread use.

Initially, for the sake of ousting gasoline engines from the market, thorium will be made as profitable as possible. But what will happen later, when a return to the past is already unlikely?

There are many questions. There are few specifics, however, as in everything new, unknown, which seems like a gamble in the first couple.

Although, the first versions of the thorium engine are already ready. They weigh about 200 kilograms. Such a device can easily be placed under a medium-sized hood.

However, no matter how breakthrough the statement of LPS specialists may seem, the very idea of \u200b\u200busing an atomic thorium engine is not new. In 2009, Lauren Culeusus showed the world community his vision of the future and demonstrated the Cadillac World Thorium Fuel Concept Car. And, despite its futuristic appearance, the main difference between the concept car was the presence of an energy source for autonomous operation, which used thorium as fuel.

“Scientists need to find a cheaper energy source than coal, with little or no carbon dioxide emissions when burned. Otherwise, this idea will not be able to develop at all ”- Robert Hargrave, a specialist in the field of studying the properties of thorium

Interesting:

Natural reserves of thorium exceed those of uranium by 3-4 times
Experts call thorium and in particular thorium-232 "nuclear fuel of the future"

Thorium fuel cycle is a nuclear fuel cycle using Thorium-232 isotopes as nuclear feedstock. Thorium-232 during the separation reaction in the reactor transfers transmutation into the artificial isotope Uranium-233, which is used as nuclear fuel. Unlike natural uranium, natural thorium contains only very small fractions of fissile material (for example, Thorium-231), which is not enough to start a nuclear chain reaction. To start the fuel cycle, it is necessary to have an additional fissile material or another source of neutrons. In a thorium reactor, Thorium-232 absorbs neutrons to eventually produce Uranium-233. Depending on the design of the reactor and the fuel cycle, the created uranium-233 isotope can be fissioned in the reactor itself or chemically separated from spent nuclear fuel and remelted into new nuclear fuel.

The thorium fuel cycle has several potential advantages over the uranium fuel cycle, including greater abundance, better physical and nuclear properties not found in plutonium and other actinides, and better resistance to nuclear proliferation, which is associated with the use of light water reactors rather than nuclear reactors. salt melts.

History of the study of thorium

The only source of thorium is yellow translucent grains of monazite (cerium phosphate)

Controversy over the world's limited uranium reserves led to initial interest in the thorium fuel cycle. It became obvious that uranium reserves are exhaustible, and thorium can replace uranium as a nuclear fuel feedstock. However, most countries have relatively rich uranium deposits and research into the thorium fuel cycle is extremely slow. A major exception is India and its three-stage nuclear program. In the 21st century, thorium's potential to resist nuclear proliferation and the characteristics of spent fuel feedstock have led to renewed interest in the thorium fuel cycle.

Oak Ridge National Laboratory used the Molten Salt Experimental Reactor using Uranium-233 as the fissile material in the 1960s to experiment and demonstrate the operation of the Molten Salt Breeder Reactor operating on the thorium cycle. Experiments with the Reactor on the Molten Salts of the possibility of thorium, using thorium fluoride (IV) dissolved in the molten salt. This reduced the need for fuel cell production. The PPC program was terminated in 1976 after the dismissal of its curator, Alvin Weinberg.

In 2006, Carlo Rubbia proposed the concept of an energy booster or "controlled accelerator", which he saw as an innovative and safe way to produce nuclear energy using existing energy acceleration technologies. Rubbia's idea offers the possibility to burn highly radioactive nuclear waste and produce energy from natural thorium and depleted uranium.

Kirk Sorensen, a former NASA scientist and Chief Nuclear Officer of Teledyne Brown Engineering, has long promoted the idea of a thorium fuel cycle, in particular Liquid Thorium Fluoride Reactors (LFRs). He pioneered research into thorium reactors while at NASA, when he was evaluating various power plant concepts for lunar colonies. In 2006, Sorensen founded the website "Energyfromthorium.com" to inform and promote this technology.

In 2011, the Massachusetts Institute of Technology concluded that, despite few barriers to the thorium fuel cycle, the current state of light water reactors provides little incentive for such a cycle to enter the market. It follows that the chance of the thorium cycle displacing the traditional uranium cycle in the current nuclear power market is extremely small, despite the potential benefits.

Nuclear reactions with thorium

During the thorium cycle Thorium-232 captures neutrons (this occurs in both fast and thermal reactors) to be converted into Thorium-233. This usually leads to the emission of electrons and antineutrinos during?-decay and the appearance of Protactinium-233. Then, during the second?-decay and re-emission of electrons and antineutrinos, Uranium-233 is formed, which is used as fuel.

Waste from fission products

Nuclear fission produces radioactive decay products that can have half-lives ranging from a few days to over 200,000 years. According to some toxicology studies, the thorium cycle can completely process actinide waste and only emit waste after fission products, and only after a few centuries the thorium reactor waste will become less toxic than uranium ores, which can be used to produce depleted uranium fuel for a light water reactor of a similar nature. power.

actinide waste

In a reactor where neutrons hit a fissile atom (for example, certain uranium isotopes), both nuclear fission and neutron capture and atom transmutation can occur. In the case of Uranium-233, transmutation leads to the production of useful nuclear fuel, as well as transuranium waste. When Uranium-233 absorbs a neutron, a fission reaction or conversion to Uranium-234 can occur. The chance of splitting or absorbing a thermal neutron is approximately 92%, while the ratio of the capture cross section to the neutron fission cross section in the case of Uranium-233 is approximately 1:12. This figure is larger than the corresponding ratios of Uranus-235 (about 1:6), Pluto-239 or Pluto-241 (both have ratios of about 1:3). The result is less transuranium waste than in a traditional uranium-plutonium fuel cycle reactor.

Uranium-233, like most actinides with a different number of neutrons, does not fissile, but when neutrons are “captured”, the fissile isotope Uranium-235 appears. If no fission or neutron capture reaction occurs in the fissile isotope, Uranium-236, Neptunium-237, Plutonium-238, and eventually the fissile isotope Plutonium-239 and heavier isotopes of plutonium appear. Neptunium-237 can be removed and stored as waste, or preserved and transmuted into plutonium, which is better fissile, while the remainder turns into Plutonium-242, then americium and curium. These, in turn, can be disposed of as waste, or returned to reactors for further transmutation and fission.

However, Protactinium-231, with a half-life of 32,700 years, is formed through reactions with Thorium-232, despite not being a transuranium waste, is the main cause of long-lived radioactive waste.

Infection with Uranium-232

Uranium-232 also appears during the reaction between fast neutrons and Uranium-233, Protactinium-233 and Thorium-232.

Uranium-232 has a relatively short half-life (68.9 years) and some of the decay products emit high-energy gamma rays, as do Radon-224, Bismuth-212, and partially Thallium-208.

The thorium cycle produces harsh gamma radiation that damages electronics, limiting its use as a trigger for nuclear bombs. Uranium-232 cannot be chemically separated from Uranium-233 found in spent nuclear fuel. However, the chemical separation of thorium from uranium removes the decay products of thorium-228 and radiation from the rest of the half-life chain, which gradually leads to the re-accumulation of thorium-228. Contamination can also be prevented by using a Molten Salt Breeder Reactor and separating Protactinium-233 before it decays to Uranium-233. Hard gamma rays can also create a radiobiological hazard requiring telepresence operation.

Nuclear fuel

As a nuclear fuel, thorium is similar to Uranium-238, which makes up most of the natural and depleted uranium. The index of the nuclear cross section of the absorbed thermal neutron and the resonance integral (the average number of the nuclear cross section of neutrons with intermediate energy) for Thorium-232 is approximately equal to three, and is one third of the corresponding index of Uranium-238.

Advantages

Thorium is estimated to be three to four times more common in the earth's crust than uranium, although in reality data on its reserves are extremely limited. Current demand for thorium is met by secondary rare earth products mined from monazite sands.

Although the fissile thermal neutron cross section of Uranium-233 is comparable to Uranium-235 and Plutonium-239, it has a much lower capture neutron cross section than the latter two isotopes, resulting in fewer absorbed non-fissile neutrons and an increase in the neutron balance. . After all, the ratio of released and absorbed neutrons in Uranium-233 is more than two in a wide range of energies, including thermal. As a result, thorium-based fuel can become the main component of a thermal breeder reactor. A breeder reactor with a uranium-plutonium cycle is forced to use the fast neutron spectrum, since in the thermal spectrum one neutron is absorbed by Plutonium-239, and on average 2 neutrons disappear during the reaction.

The thorium-based fuel also exhibits excellent physical and chemical properties, which improves the performance of the reactor and repository. Compared to uranium dioxide, the predominant reactor fuel, thorium dioxide has a higher influence temperature, thermal conductivity, and a lower coefficient of thermal expansion. Thorium dioxide also shows better chemical stability and, unlike uranium dioxide, is not capable of further oxidation.

Because the uranium-233 produced in thorium fuel is heavily contaminated with uranium-232 in proposed reactor concepts, thorium spent fuel is resistant to weapons proliferation. Uranium-232 cannot be chemically separated from Uranium-233 and has several decay products that emit high-energy gamma rays. These high-energy protons carry a radioactive hazard, necessitating remote work with separated uranium and nuclear detection of such substances.

Substances based on uranium spent fuel with a long half-life (from 1,000 to 1,000,000 years) carry a radioactive hazard due to the presence of plutonium and other minor actinides, after which long-lived fission products reappear. One neutron captured by Uranium-238 is enough to create transuranium elements, while five such "captures" are needed for a similar process with Thorium-232. 98-99% of the thorium nuclear cycle results in the fission of Uranium-233 or Uranium-235, so fewer long-lived transuranium elements are produced. Because of this, thorium appears to be a potentially attractive alternative to uranium in mixed oxide fuels to minimize the production of transuranium substances and maximize the amount of decayed plutonium.

disadvantages

There are several obstacles to the use of thorium as a nuclear fuel, in particular for solid fuel reactors.

Unlike uranium, naturally occurring thorium is generally single-nuclear and contains no fissile isotopes. Fissile material, typically Uranium-233, Uranium-235, or plutonium, must be added to achieve criticality. Together with the high sintering temperature required for thorium dioxide, this complicates the production of the fuel. Oak Ridge National Laboratory conducted experiments on thorium tetrafluoride as a fuel for a molten salt reactor in 1964-1969. It was expected that the process of production and separation of substances from pollutants would be facilitated to slow down or stop the chain reaction.

In a single fuel cycle (for example, Uranium-233 processing in the reactor itself), more severe burnup is needed to achieve the desired neutron balance. Although thorium dioxide is capable of generating 150,000-170,000 megawatt-days/ton at the Fort St. Raine and Jülich Experimental Nuclear Power Plants, there are serious challenges to achieve such performance in light water reactors, which constitute the vast majority of existing reactors.

In a single thorium fuel cycle, the remaining uranium-233 remains in the spent fuel as a long-lived isotope.

Another hurdle is that the thorium fuel cycle takes comparatively longer to convert Thorium-232 into Uranium-233. The half-life of Protactinium-233 is approximately 27 days, which is much longer than the half-life of Neptunium-239. As a result, the main ingredient in thorium fuel is the strong Protactinium-239. Protactinium-239 is a strong neutron absorber, and although conversion to fissile Uranium-235 can occur, it takes twice as many neutrons to be absorbed, which destroys the neutron balance and increases the likelihood of transuranium production.

On the other hand, if solid thorium is used in a closed fuel cycle where uranium-233 is processed, remote interaction is necessary to produce the fuel due to the high levels of radiation provoked by the decay products of uranium-232. This is also true when it comes to recycled thorium due to the presence of thorium-228 being part of the decay chain. Moreover, unlike the proven technology for reprocessing uranium fuel, the technology for reprocessing thorium is now only developing.

Although the presence of Uranium-232 complicates matters, there are published documents showing that Uranium-233 was used in nuclear tests. The US tested a sophisticated bomb containing uranium-233 and plutonium in the core during Operation Teapot in 1955, although a much lower TNT equivalent was achieved.

Although thorium-based fuels produce much less transuranium than uranium-based counterparts, a certain amount of long-lived actinides with a long radioactive background, in particular Protactinium-231, can sometimes be produced.