ITER as an excellent example of deficiencies in the extraction of energy from fusion.
A year ago, I criticized thermonuclear fusion as an energy source in the article " Thermonuclear reactors: not the kind that should have been ." The article aroused great interest, and I was asked to write a sequel to continue the discussion with the readers of Bulletin magazine. But first, a small summary for those who have just joined us.
I am a physicist, a researcher who has been working on nuclear fusion experiments for 25 years at the Plasma Physics Laboratory in Princeton , New Jersey. I was interested in research in plasma physics and neutron production related to research and development of nuclear energy. Now I am retired, and I can look at this whole area impassively, and it seems to me that a commercial thermonuclear reactor will introduce more problems than it can solve.
Therefore, I feel that I must dispel all kinds of sensations that have arisen around the topic of thermonuclear energy, which is often called the “ideal” energy source, and present it as a magical solution to world energy problems. Last year’s article argued that all the constantly advertised capabilities of this ideal energy (usually “endless, cheap, clean, safe, free from radiation”) break into a harsh reality, and that a fusion reactor actually approaches the opposite of the idea of ​​an ideal source of energy. . But in that article, the shortcomings of conceptual fusion reactors were mainly discussed, and supporters of this idea continue to insist that these shortcomings will someday be corrected.
However, now we have come to the point where we can for the first time explore a prototype thermonuclear power plant in the real world: the International Thermonuclear Experimental Reactor ( ITER ), which is being built in Cadarache in southern France. And although there are still years before its launch, the ITER project has progressed sufficiently so that it can be studied as a test case by a bubble scheme known as tokamak - the most promising approach to obtaining thermonuclear energy on Earth based on a magnetic trap. In December 2017, the ITER project management announced the completion of 50% of the construction tasks. This important milestone allows us to hope for the completion of this project, the only facility on Earth that even remotely resembles a practical thermonuclear reactor. As the New York Times wrote, this installation "is being built to test a long-held dream: that nuclear fusion, an atomic reaction taking place in the Sun and in hydrogen bombs, can be monitored and energy extracted from it."
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Plasma physicists treat ITER as the first magnetic trap, which in principle will be able to demonstrate a “burning plasma” in which heating by alpha particles appearing in nuclear reactions will become the main way of maintaining plasma temperature. Such conditions require that thermonuclear energy is at least five times greater than the external energy heating the plasma. And although this energy will not be converted into electricity, the ITER project is generally considered a critical step along the road to creating a practical thermonuclear power plant - this is what we are going to do.
Let's see what conclusions can be drawn from the unrecoverable shortcomings of thermonuclear reactors, examining the ITER project, concentrating on four areas: electricity consumption, tritium fuel losses, neutron activation, and the need for cooling water. The physical scheme of this project worth $ 20-30 billion is shown in the photo below.
On the ITER website, visitors are greeted with the statement “Unlimited Energy” - the battle cry of the thermonuclear energy enthusiasts of the whole world. The irony of this slogan passes by the project participants and the public. But everyone who followed the construction of the project for the last five years - and it’s easy to follow the photographs and descriptions on the project site - would be surprised by the huge amount of energy spent on it.
The site, in fact, boasts this embedded energy, advertising each of the ITER subsystems as the largest system of this type. For example, a cryostat, a liquid-helium cooler, is the largest stainless steel vacuum container in the world, and the tokamak itself will weigh like three Eiffel towers. The total weight of the main ITER unit will be 400,000 tons, of which the foundation and buildings weighing 340,000 tons and the tokamak weighing 23,000 tons will be the heaviest.
But this should not be admired, but terrified, since “the biggest” means a large investment of capital and energy, which should be on the side of the “loan” of the energy ledger. And most of this energy was obtained from fossil fuels, which left an incredibly huge carbon footprint on the preparation for the construction and the construction itself of all utility buildings and the reactor itself.
At the construction site of the reactor, fossil fuel-fired machines dig huge amounts of earth to a depth of 20 meters, make and pour countless tons of cement. The world's largest trucks (running on fossil fuels) carry huge reactor components to the construction site. Fossil fuel is burned during the excavation, transportation and processing of materials necessary for the manufacture of components of a fusion reactor.
You can ask how much of the energy spent on this will be able to return - but to return it, of course, will not work. But the materialization of this incredible waste of energy is only the first component of the irony associated with "unlimited energy."
Next to these buildings, there is a power station with an area of ​​4 hectares, with massive substations transmitting up to 600 MW of electricity from the local electrical network - this is enough to supply an average city. This energy will be needed to support the workers needs of ITER; no energy will ever go out, since the ITER design does not involve the conversion of thermonuclear energy into electricity. Recall that ITER is a test equipment, it only demonstrates the efficiency of the concept of simulating the inner part of the Sun and the combination of atoms under control; ITER is not intended to generate electricity.
The presence of an electrical substation speaks of the huge energy costs for the operation of the ITER project - and in general any installation for synthesis. Thermonuclear reactors are experimental installations , and two types of electricity consumption take place in them. The first is the necessary auxiliary systems, for example, cryostats, vacuum pumps, heating, ventilation and air conditioning of buildings; this energy is wasted all the time, even when the plasma is inactive. In the case of ITER, this uninterrupted flow of electricity is in the range of 75–110 MW, as JS Gascon and co-authors wrote in a 2012 article for Fusion Science & Technology, “Electrical and Electrical Distribution”.
The second type of consumption is associated with the plasma itself and it works in pulses. ITER will require at least 300 MW for several tens of seconds to heat the plasma and establish its necessary flows. In the 400-second working phase, about 200 MW will be required to support thermonuclear burning and control plasma stability.
Even during the remaining eight years of power plant construction, energy consumption will be in the region of 30 MW - this is another addition to the total amount of waste that precedes future uninterrupted energy waste.
However, much of the information about energy spending — and the specifics that ITER will not generate electricity, but heat — was lost when the project was presented to the public.
The New Energy Times website recently posted a detailed article, “The ITER of Energy Multiplication Myth,” describing how the public relations department of this installation spread poorly worded information and confused the media. A typical distributed statement looks like “ITER will produce 500 MW of energy, consuming 50 MW”, from which it would seem that both numbers describe electrical energy.
The site clearly describes that these 500 MW of output energy are related to the fusion energy contained in neutrons and alpha particles, and are not related to electricity. And the mentioned 50 MW relate to the energy transmitted to the plasma to support its temperature and currents - and this is only a small part of the total energy consumption of the reactor. As mentioned earlier, it varies from 300 to 400 MW.
Criticism of the New Energy Times is technically correct and draws attention to the enormous demands of electricity imposed by any thermonuclear installation. It has always been known that launching any fusion system requires tremendous energy. But tokamak systems also require hundreds of megawatts of electrical energy just to work.
However, with the advertised work ITER there are more serious problems than the incorrect description of the energy consumed and emitted. Nobody argues that the plant will consume 300 MW or more of energy - the main question is whether ITER will deliver 500 MW of at least some energy. And this question concerns the vital tritium fuel - its supply, the desire to use it and the actions necessary to optimize its use. Among other misconceptions is the real nature of the product of synthesis.
The most active fuel for the synthesis will be a mixture of isotopes of hydrogen, deuterium and tritium, in a ratio of 50-50. This fuel, which is often recorded as DT, has a neutron yield 100 times more than pure deuterium, but also exceeds its radioactive consequences.
There is a lot of deuterium in ordinary water, but there is no natural deposits of tritium - the half-life of this isotope is only 12.3 years. The ITER website claims that the project will take tritium fuel from “world reserves of tritium”. These reserves consist of tritium recovered from the heavy water of the CANDU nuclear reactors, which are mainly located in Ontario in Canada, and are also found in South Korea. Also potentially fuel can be obtained from Romania. Today's “world reserves” of tritium are about 25 kg, and they increase by about a pound per year, as they wrote in an article from 2013 entitled “Estimation of Tritium Stocks for ITER” in the journal Fusion Engineering and Design. Peak reserves of tritium should reach 2030.
Although thermonuclear supporters happily talk about the synthesis of deuterium and tritium, in fact they are extremely afraid to use tritium for two reasons: firstly, it is radioactive, therefore there are safety problems associated with the possibility of its release into the environment. Secondly, the bombardment of the reactor vessel with neutrons leads to the inevitable production of radioactive materials, which requires increased protection, which, in turn, seriously complicates access to the reactor for its maintenance and raises problems associated with the storage of radioactive waste.
For 65 years of research in hundreds of installations, tritium has used only two systems with magnetic traps: Tokamak Fusion Test Reactor in my old plasma laboratory at Princeton, and Joint European Tokamak near the village of Calham, United Kingdom.
Current ITER plans include acquiring and consuming at least 1 kg of tritium per year. Assuming that the project manages to find a suitable source of tritium and have the courage to use it, will the goal of 500 MW of fusion energy be achieved? Nobody knows.
The “first plasma” in ITER should occur in 2025. It will be followed by a leisurely 10 years of continued assembly of machines and periodic plasma launches with the help of hydrogen and helium. These gases do not emit neutrons, and therefore will allow to solve problems and to optimize the operation of the plasma with a minimum radiation hazard. Plasma instability must be kept within the framework, and it will be heated and maintained at a high temperature. Therefore, it will be necessary to reduce the influx of atoms other than hydrogen.
According to the schedule, ITER will start using deuterium and tritium in the late 2030s. But there are no guarantees that he will be able to reach the goal of 500 MW; to generate a large amount of thermonuclear energy, among other things, it is required to develop an optimal recipe for stuffing deuterium and tritium in the form of frozen balls, to support beams from particles, pumping gas and recycling waste. During the inevitable trial and error method in the early 2040s, the fusion energy on ITER is likely to reach only a small fraction of 500 MW, and all used tritium will be lost.
Analysis of the use of DT on ITER suggests that only 2% of the injected tritium will burn, so 98% of the tritium will be released unharmed. And although a fairly large part of tritium will simply exit through the plasma exhaust, a lot of tritium will have to be constantly collected from the surfaces of the reactor capacity, radiation injectors, pump channels and other devices. The atoms of tritium, several times passing through all these circles of hell, through plasma, vacuum, processing and power systems, will partially end up in an eternal trap in the walls of the reactor and its components, as well as in the plasma diagnostic and heating system.
The tritium leakage at high temperatures in many materials is still poorly understood, as R. A. Cause and his co-authors explained in the article " Tritium barriers and tritium dispersion in fusion reactors ." It is possible that the leakage of a small part of the caught tritium into the walls and then into the channels of the liquid and gaseous coolers cannot be avoided. Most of this tritium will eventually disintegrate, but it will inevitably enter the environment through circulating water that cools the reactor.
Developers of the tokamak of the future usually assume that all burnt tritium will be replaced due to the absorption of neutrons by lithium surrounding the plasma. But even this fantasy completely ignores the tritium that will be lost in various parts of the reactor subsystems. ITER will demonstrate that the accumulation of lost tritium can exceed the amount of burned and can be replaced only by buying expensive tritium from nuclear reactors.
As noted earlier, ITER is expected to produce 500 MW of thermonuclear, rather than electrical, energy. But what thermonuclear supporters do not tell you is that the thermonuclear energy obtained will not be some kind of innocent radiation like solar radiation, but 80% will consist of high-energy neutron fluxes, the main result of which will be only the production of a huge amount of radioactive waste during bombardment reactor and its components.
Only 2% of the neutrons will be intercepted by test modules used to study the appearance of tritium in lithium, and 98% of the neutron fluxes will simply collide with the walls of the reactor or devices located there.
In nuclear reactors, no more than 3% of the decay energy is transferred to neutrons. But ITER will be like some kind of household appliances that convert hundreds of megawatts of electricity into neutron fluxes. A strange feature of DT reactors is that the vast majority of thermal energy is not produced in the plasma, but inside the thick steel walls of the reactor, dissipating energy from collisions with neutrons. In principle, this thermal neutron energy can somehow be turned back into electricity, with very low efficiency, but during the development of the ITER project this problem was decided not to be solved. This task was postponed until the construction of the so-called "demonstration reactors", which the supporters of the thermonuclear are planning to build in the second half of the century.
The long-known problem of thermonuclear energy is the damage to materials exposed to neutron radiation, because of which they swell, become brittle and wear out quickly. But it turned out that the total ITER operation time with a high neutron yield would be too small for the reactor structure to suffer, however interactions with neutrons would still result in dangerous radioactivity in the reactor components, resulting in an unimaginable amount of radioactive waste - 30,000 tons.
A tokamak in ITER will surround a monstrous concrete cylinder 3.5 m thick, 30 m in diameter and 30 m high, called a bioschit. It will protect the outside world from X-rays, gamma rays and random neutrons. The reactor vessel and non-structural components, both inside and outside the reactor, inside this bio-shield will become extremely radioactive due to neutron fluxes. It will take more time for maintenance and repair, since all this maintenance will be carried out with the help of equipment with remote control.
From a much smaller pilot project JET in Britain, radioactive waste is expected to be about 3000 cubic meters, and the cost of its decommissioning is estimated at $ 300 million, according to the Financial Times . But these numbers pale before 30,000 tons of ITER radioactive waste. Fortunately, much of this induced radioactivity will disappear in a few decades, but after 100 years, about 6,000 tons of waste will still be dangerous, and they will need to be stored in a special storage, as indicated in the “Waste and decommissioning” section of the final scheme ITER.
Periodic transportation and storage of radioactive components outside the project areas, as well as the final decommissioning of the entire reactor complex are costly energy tasks that will further affect the expenditure part of the energy ledger.
Water will be required to remove heat from the ITER reactor, plasma heating systems, tokamak electrical systems, cryogenic refrigerators, and power magnets. If we take into account the thermonuclear reaction, the total heat energy can reach 1000 MW, but even without a thermonuclear reaction, the complex will consume up to 500 MW of energy, which eventually will turn into heat to be removed. ITER will demonstrate that thermonuclear energy consumes much more water than any other power plant due to the huge parasitic energy consumption, which turns into additional heat, which must be diverted (parasitic is the absorption of the same energy that the reactor itself produces).
Cooling water will be taken from the Provence Canal diverted from the Durance River, and most of the heat will be released into the atmosphere with the help of cooling towers. During reactor operation, the total flow of cooling water will be 12 cubic meters per minute - more than a third of the flow in the channel itself. Such a flow is able to support the functioning of a city with a population of one million (ITER’s daily water demand will be much smaller, since the power pulses of the reactor will last for 400 seconds with up to 20 pulses per day, and the cooling water will be reused).
And although ITER does not produce anything other than neutrons, its maximum coolant flow will still be almost half the flow of a real-life station burning coal or nuclear fuel and delivering 1000 MW of electrical energy. In ITER, pumps pumping water over 36 kilometers of cooling system pipes will consume 56 MW of energy.
A large fusion station such as ITER can work only in places like French Cadarache, where there is access to many powerful power lines and to the water supply system. Over the past decades, the abundance of fresh water and unlimited cold water from the ocean made it possible to implement a large number of thermoelectric stations of gigawatt capacity. Given the reduced availability of fresh water and even cold ocean water , difficulties in supplying coolant alone will make the widespread use of fusion reactors impractical.
ITER will work well or badly, its main legacy will be an impressive example of many years of international cooperation from different states, both politically friendly and quite hostile - just like the International Space Station. Critics argue that international cooperation has greatly increased the cost and duration of the project, but the cost of $ 20-30 billion does not go beyond large nuclear projects - such as, for example, power plants, the construction of which was allowed in recent years in the US ( VC Summer and Vogtl ) [ Westinghouse was supposed to build new blocks on VC Summer, but excessive inflation of the cost and timing of the project, as well as other problems, led to the bankruptcy of the company; building blocks canceled. In December 2012, during transportation by rail in the US, a new 300-ton nuclear reactor for the Vogtl nuclear power plant, manufactured in South Korea, the platform with it seriously tilted, almost to the ground. However, the reactor was not damaged. / approx. trans. ] and in Western Europe ( Hinckley and Flamanville) [the excessive appreciation of the Hinckley project questioned its completion; At the operating Flamanville NPP, two accidents have occurred over the past six years (without environmental consequences), and the cost of building a new unit has increased threefold compared to the initial one, while construction continues / approx. trans. ], as well as the MOX nuclear fuel project in the US region of Savannah River [ near the nuclear repository / approx. trans. ]. All these projects have experienced a tripling of the cost of construction, and the construction time has increased by years and even decades . The main problem is that all nuclear power plants, be it synthesis or decay, are extremely complex and prohibitively expensive [the construction of two power units of the first stage of the Tianwan NPP , which Rosatom built for China, cost $ 3 billion and took 11 years. The third unit was built in 5 years / approx. trans. ].
The second invaluable role of ITER will be its influence on the planning of energy-generating systems. If successful, ITER will allow physicists to study long-lived high-temperature synthesizing plasma. But as a prototype, the ITER power plant will obviously sow desolation and destruction by a neutron source fed by tritium produced in nuclear reactors, consuming hundreds of megawatts of electricity from the local grid and requiring unprecedented volumes of water for cooling. The damage due to neutrons will increase, and the remaining characteristics will remain the same in any subsequent thermonuclear reactor created in an attempt to generate enough electricity to surpass their own requests.
Faced with such a reality, even energy planners with brighter eyes than ever may want to abandon thermonuclear energy. Instead of proclaiming the dawn of a new energy era, ITER is likely to play a role similar to fast breeder reactors , whose shortcomings prevented another imaginary source of “unlimited energy” and ensured the domination of light water reactors [ Russia’s breeder reactors in two years, a new unique lead-cooled fast neutron reactor will be built / approx. trans. ]
I am a physicist, a researcher who has been working on nuclear fusion experiments for 25 years at the Plasma Physics Laboratory in Princeton , New Jersey. I was interested in research in plasma physics and neutron production related to research and development of nuclear energy. Now I am retired, and I can look at this whole area impassively, and it seems to me that a commercial thermonuclear reactor will introduce more problems than it can solve.
Therefore, I feel that I must dispel all kinds of sensations that have arisen around the topic of thermonuclear energy, which is often called the “ideal” energy source, and present it as a magical solution to world energy problems. Last year’s article argued that all the constantly advertised capabilities of this ideal energy (usually “endless, cheap, clean, safe, free from radiation”) break into a harsh reality, and that a fusion reactor actually approaches the opposite of the idea of ​​an ideal source of energy. . But in that article, the shortcomings of conceptual fusion reactors were mainly discussed, and supporters of this idea continue to insist that these shortcomings will someday be corrected.
However, now we have come to the point where we can for the first time explore a prototype thermonuclear power plant in the real world: the International Thermonuclear Experimental Reactor ( ITER ), which is being built in Cadarache in southern France. And although there are still years before its launch, the ITER project has progressed sufficiently so that it can be studied as a test case by a bubble scheme known as tokamak - the most promising approach to obtaining thermonuclear energy on Earth based on a magnetic trap. In December 2017, the ITER project management announced the completion of 50% of the construction tasks. This important milestone allows us to hope for the completion of this project, the only facility on Earth that even remotely resembles a practical thermonuclear reactor. As the New York Times wrote, this installation "is being built to test a long-held dream: that nuclear fusion, an atomic reaction taking place in the Sun and in hydrogen bombs, can be monitored and energy extracted from it."
')
Plasma physicists treat ITER as the first magnetic trap, which in principle will be able to demonstrate a “burning plasma” in which heating by alpha particles appearing in nuclear reactions will become the main way of maintaining plasma temperature. Such conditions require that thermonuclear energy is at least five times greater than the external energy heating the plasma. And although this energy will not be converted into electricity, the ITER project is generally considered a critical step along the road to creating a practical thermonuclear power plant - this is what we are going to do.
Let's see what conclusions can be drawn from the unrecoverable shortcomings of thermonuclear reactors, examining the ITER project, concentrating on four areas: electricity consumption, tritium fuel losses, neutron activation, and the need for cooling water. The physical scheme of this project worth $ 20-30 billion is shown in the photo below.
Wrong motto
On the ITER website, visitors are greeted with the statement “Unlimited Energy” - the battle cry of the thermonuclear energy enthusiasts of the whole world. The irony of this slogan passes by the project participants and the public. But everyone who followed the construction of the project for the last five years - and it’s easy to follow the photographs and descriptions on the project site - would be surprised by the huge amount of energy spent on it.
The site, in fact, boasts this embedded energy, advertising each of the ITER subsystems as the largest system of this type. For example, a cryostat, a liquid-helium cooler, is the largest stainless steel vacuum container in the world, and the tokamak itself will weigh like three Eiffel towers. The total weight of the main ITER unit will be 400,000 tons, of which the foundation and buildings weighing 340,000 tons and the tokamak weighing 23,000 tons will be the heaviest.
But this should not be admired, but terrified, since “the biggest” means a large investment of capital and energy, which should be on the side of the “loan” of the energy ledger. And most of this energy was obtained from fossil fuels, which left an incredibly huge carbon footprint on the preparation for the construction and the construction itself of all utility buildings and the reactor itself.
At the construction site of the reactor, fossil fuel-fired machines dig huge amounts of earth to a depth of 20 meters, make and pour countless tons of cement. The world's largest trucks (running on fossil fuels) carry huge reactor components to the construction site. Fossil fuel is burned during the excavation, transportation and processing of materials necessary for the manufacture of components of a fusion reactor.
You can ask how much of the energy spent on this will be able to return - but to return it, of course, will not work. But the materialization of this incredible waste of energy is only the first component of the irony associated with "unlimited energy."
Next to these buildings, there is a power station with an area of ​​4 hectares, with massive substations transmitting up to 600 MW of electricity from the local electrical network - this is enough to supply an average city. This energy will be needed to support the workers needs of ITER; no energy will ever go out, since the ITER design does not involve the conversion of thermonuclear energy into electricity. Recall that ITER is a test equipment, it only demonstrates the efficiency of the concept of simulating the inner part of the Sun and the combination of atoms under control; ITER is not intended to generate electricity.
The presence of an electrical substation speaks of the huge energy costs for the operation of the ITER project - and in general any installation for synthesis. Thermonuclear reactors are experimental installations , and two types of electricity consumption take place in them. The first is the necessary auxiliary systems, for example, cryostats, vacuum pumps, heating, ventilation and air conditioning of buildings; this energy is wasted all the time, even when the plasma is inactive. In the case of ITER, this uninterrupted flow of electricity is in the range of 75–110 MW, as JS Gascon and co-authors wrote in a 2012 article for Fusion Science & Technology, “Electrical and Electrical Distribution”.
The second type of consumption is associated with the plasma itself and it works in pulses. ITER will require at least 300 MW for several tens of seconds to heat the plasma and establish its necessary flows. In the 400-second working phase, about 200 MW will be required to support thermonuclear burning and control plasma stability.
Even during the remaining eight years of power plant construction, energy consumption will be in the region of 30 MW - this is another addition to the total amount of waste that precedes future uninterrupted energy waste.
However, much of the information about energy spending — and the specifics that ITER will not generate electricity, but heat — was lost when the project was presented to the public.
Truth about energy
The New Energy Times website recently posted a detailed article, “The ITER of Energy Multiplication Myth,” describing how the public relations department of this installation spread poorly worded information and confused the media. A typical distributed statement looks like “ITER will produce 500 MW of energy, consuming 50 MW”, from which it would seem that both numbers describe electrical energy.
The site clearly describes that these 500 MW of output energy are related to the fusion energy contained in neutrons and alpha particles, and are not related to electricity. And the mentioned 50 MW relate to the energy transmitted to the plasma to support its temperature and currents - and this is only a small part of the total energy consumption of the reactor. As mentioned earlier, it varies from 300 to 400 MW.
Criticism of the New Energy Times is technically correct and draws attention to the enormous demands of electricity imposed by any thermonuclear installation. It has always been known that launching any fusion system requires tremendous energy. But tokamak systems also require hundreds of megawatts of electrical energy just to work.
However, with the advertised work ITER there are more serious problems than the incorrect description of the energy consumed and emitted. Nobody argues that the plant will consume 300 MW or more of energy - the main question is whether ITER will deliver 500 MW of at least some energy. And this question concerns the vital tritium fuel - its supply, the desire to use it and the actions necessary to optimize its use. Among other misconceptions is the real nature of the product of synthesis.
Problems with tritium
The most active fuel for the synthesis will be a mixture of isotopes of hydrogen, deuterium and tritium, in a ratio of 50-50. This fuel, which is often recorded as DT, has a neutron yield 100 times more than pure deuterium, but also exceeds its radioactive consequences.
There is a lot of deuterium in ordinary water, but there is no natural deposits of tritium - the half-life of this isotope is only 12.3 years. The ITER website claims that the project will take tritium fuel from “world reserves of tritium”. These reserves consist of tritium recovered from the heavy water of the CANDU nuclear reactors, which are mainly located in Ontario in Canada, and are also found in South Korea. Also potentially fuel can be obtained from Romania. Today's “world reserves” of tritium are about 25 kg, and they increase by about a pound per year, as they wrote in an article from 2013 entitled “Estimation of Tritium Stocks for ITER” in the journal Fusion Engineering and Design. Peak reserves of tritium should reach 2030.
Although thermonuclear supporters happily talk about the synthesis of deuterium and tritium, in fact they are extremely afraid to use tritium for two reasons: firstly, it is radioactive, therefore there are safety problems associated with the possibility of its release into the environment. Secondly, the bombardment of the reactor vessel with neutrons leads to the inevitable production of radioactive materials, which requires increased protection, which, in turn, seriously complicates access to the reactor for its maintenance and raises problems associated with the storage of radioactive waste.
For 65 years of research in hundreds of installations, tritium has used only two systems with magnetic traps: Tokamak Fusion Test Reactor in my old plasma laboratory at Princeton, and Joint European Tokamak near the village of Calham, United Kingdom.
Current ITER plans include acquiring and consuming at least 1 kg of tritium per year. Assuming that the project manages to find a suitable source of tritium and have the courage to use it, will the goal of 500 MW of fusion energy be achieved? Nobody knows.
The “first plasma” in ITER should occur in 2025. It will be followed by a leisurely 10 years of continued assembly of machines and periodic plasma launches with the help of hydrogen and helium. These gases do not emit neutrons, and therefore will allow to solve problems and to optimize the operation of the plasma with a minimum radiation hazard. Plasma instability must be kept within the framework, and it will be heated and maintained at a high temperature. Therefore, it will be necessary to reduce the influx of atoms other than hydrogen.
According to the schedule, ITER will start using deuterium and tritium in the late 2030s. But there are no guarantees that he will be able to reach the goal of 500 MW; to generate a large amount of thermonuclear energy, among other things, it is required to develop an optimal recipe for stuffing deuterium and tritium in the form of frozen balls, to support beams from particles, pumping gas and recycling waste. During the inevitable trial and error method in the early 2040s, the fusion energy on ITER is likely to reach only a small fraction of 500 MW, and all used tritium will be lost.
Analysis of the use of DT on ITER suggests that only 2% of the injected tritium will burn, so 98% of the tritium will be released unharmed. And although a fairly large part of tritium will simply exit through the plasma exhaust, a lot of tritium will have to be constantly collected from the surfaces of the reactor capacity, radiation injectors, pump channels and other devices. The atoms of tritium, several times passing through all these circles of hell, through plasma, vacuum, processing and power systems, will partially end up in an eternal trap in the walls of the reactor and its components, as well as in the plasma diagnostic and heating system.
The tritium leakage at high temperatures in many materials is still poorly understood, as R. A. Cause and his co-authors explained in the article " Tritium barriers and tritium dispersion in fusion reactors ." It is possible that the leakage of a small part of the caught tritium into the walls and then into the channels of the liquid and gaseous coolers cannot be avoided. Most of this tritium will eventually disintegrate, but it will inevitably enter the environment through circulating water that cools the reactor.
Developers of the tokamak of the future usually assume that all burnt tritium will be replaced due to the absorption of neutrons by lithium surrounding the plasma. But even this fantasy completely ignores the tritium that will be lost in various parts of the reactor subsystems. ITER will demonstrate that the accumulation of lost tritium can exceed the amount of burned and can be replaced only by buying expensive tritium from nuclear reactors.
Radiation and radioactive waste thermonuclear
As noted earlier, ITER is expected to produce 500 MW of thermonuclear, rather than electrical, energy. But what thermonuclear supporters do not tell you is that the thermonuclear energy obtained will not be some kind of innocent radiation like solar radiation, but 80% will consist of high-energy neutron fluxes, the main result of which will be only the production of a huge amount of radioactive waste during bombardment reactor and its components.
Only 2% of the neutrons will be intercepted by test modules used to study the appearance of tritium in lithium, and 98% of the neutron fluxes will simply collide with the walls of the reactor or devices located there.
In nuclear reactors, no more than 3% of the decay energy is transferred to neutrons. But ITER will be like some kind of household appliances that convert hundreds of megawatts of electricity into neutron fluxes. A strange feature of DT reactors is that the vast majority of thermal energy is not produced in the plasma, but inside the thick steel walls of the reactor, dissipating energy from collisions with neutrons. In principle, this thermal neutron energy can somehow be turned back into electricity, with very low efficiency, but during the development of the ITER project this problem was decided not to be solved. This task was postponed until the construction of the so-called "demonstration reactors", which the supporters of the thermonuclear are planning to build in the second half of the century.
The long-known problem of thermonuclear energy is the damage to materials exposed to neutron radiation, because of which they swell, become brittle and wear out quickly. But it turned out that the total ITER operation time with a high neutron yield would be too small for the reactor structure to suffer, however interactions with neutrons would still result in dangerous radioactivity in the reactor components, resulting in an unimaginable amount of radioactive waste - 30,000 tons.
A tokamak in ITER will surround a monstrous concrete cylinder 3.5 m thick, 30 m in diameter and 30 m high, called a bioschit. It will protect the outside world from X-rays, gamma rays and random neutrons. The reactor vessel and non-structural components, both inside and outside the reactor, inside this bio-shield will become extremely radioactive due to neutron fluxes. It will take more time for maintenance and repair, since all this maintenance will be carried out with the help of equipment with remote control.
From a much smaller pilot project JET in Britain, radioactive waste is expected to be about 3000 cubic meters, and the cost of its decommissioning is estimated at $ 300 million, according to the Financial Times . But these numbers pale before 30,000 tons of ITER radioactive waste. Fortunately, much of this induced radioactivity will disappear in a few decades, but after 100 years, about 6,000 tons of waste will still be dangerous, and they will need to be stored in a special storage, as indicated in the “Waste and decommissioning” section of the final scheme ITER.
Periodic transportation and storage of radioactive components outside the project areas, as well as the final decommissioning of the entire reactor complex are costly energy tasks that will further affect the expenditure part of the energy ledger.
Water world
Water will be required to remove heat from the ITER reactor, plasma heating systems, tokamak electrical systems, cryogenic refrigerators, and power magnets. If we take into account the thermonuclear reaction, the total heat energy can reach 1000 MW, but even without a thermonuclear reaction, the complex will consume up to 500 MW of energy, which eventually will turn into heat to be removed. ITER will demonstrate that thermonuclear energy consumes much more water than any other power plant due to the huge parasitic energy consumption, which turns into additional heat, which must be diverted (parasitic is the absorption of the same energy that the reactor itself produces).
Cooling water will be taken from the Provence Canal diverted from the Durance River, and most of the heat will be released into the atmosphere with the help of cooling towers. During reactor operation, the total flow of cooling water will be 12 cubic meters per minute - more than a third of the flow in the channel itself. Such a flow is able to support the functioning of a city with a population of one million (ITER’s daily water demand will be much smaller, since the power pulses of the reactor will last for 400 seconds with up to 20 pulses per day, and the cooling water will be reused).
And although ITER does not produce anything other than neutrons, its maximum coolant flow will still be almost half the flow of a real-life station burning coal or nuclear fuel and delivering 1000 MW of electrical energy. In ITER, pumps pumping water over 36 kilometers of cooling system pipes will consume 56 MW of energy.
A large fusion station such as ITER can work only in places like French Cadarache, where there is access to many powerful power lines and to the water supply system. Over the past decades, the abundance of fresh water and unlimited cold water from the ocean made it possible to implement a large number of thermoelectric stations of gigawatt capacity. Given the reduced availability of fresh water and even cold ocean water , difficulties in supplying coolant alone will make the widespread use of fusion reactors impractical.
ITER influence
ITER will work well or badly, its main legacy will be an impressive example of many years of international cooperation from different states, both politically friendly and quite hostile - just like the International Space Station. Critics argue that international cooperation has greatly increased the cost and duration of the project, but the cost of $ 20-30 billion does not go beyond large nuclear projects - such as, for example, power plants, the construction of which was allowed in recent years in the US ( VC Summer and Vogtl ) [ Westinghouse was supposed to build new blocks on VC Summer, but excessive inflation of the cost and timing of the project, as well as other problems, led to the bankruptcy of the company; building blocks canceled. In December 2012, during transportation by rail in the US, a new 300-ton nuclear reactor for the Vogtl nuclear power plant, manufactured in South Korea, the platform with it seriously tilted, almost to the ground. However, the reactor was not damaged. / approx. trans. ] and in Western Europe ( Hinckley and Flamanville) [the excessive appreciation of the Hinckley project questioned its completion; At the operating Flamanville NPP, two accidents have occurred over the past six years (without environmental consequences), and the cost of building a new unit has increased threefold compared to the initial one, while construction continues / approx. trans. ], as well as the MOX nuclear fuel project in the US region of Savannah River [ near the nuclear repository / approx. trans. ]. All these projects have experienced a tripling of the cost of construction, and the construction time has increased by years and even decades . The main problem is that all nuclear power plants, be it synthesis or decay, are extremely complex and prohibitively expensive [the construction of two power units of the first stage of the Tianwan NPP , which Rosatom built for China, cost $ 3 billion and took 11 years. The third unit was built in 5 years / approx. trans. ].
The second invaluable role of ITER will be its influence on the planning of energy-generating systems. If successful, ITER will allow physicists to study long-lived high-temperature synthesizing plasma. But as a prototype, the ITER power plant will obviously sow desolation and destruction by a neutron source fed by tritium produced in nuclear reactors, consuming hundreds of megawatts of electricity from the local grid and requiring unprecedented volumes of water for cooling. The damage due to neutrons will increase, and the remaining characteristics will remain the same in any subsequent thermonuclear reactor created in an attempt to generate enough electricity to surpass their own requests.
Faced with such a reality, even energy planners with brighter eyes than ever may want to abandon thermonuclear energy. Instead of proclaiming the dawn of a new energy era, ITER is likely to play a role similar to fast breeder reactors , whose shortcomings prevented another imaginary source of “unlimited energy” and ensured the domination of light water reactors [ Russia’s breeder reactors in two years, a new unique lead-cooled fast neutron reactor will be built / approx. trans. ]
Source: https://habr.com/ru/post/374379/
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