ITER as an excellent example of deficiencies in energy production from fusion

Original author: Daniel Jassby
  • Transfer
A year ago, I criticized thermonuclear fusion as a source of energy in an article entitled “ Thermonuclear Reactors: Not What They Should Be .” The article aroused great interest, and I was asked to write a sequel to continue discussing the topic with readers of Bulletin magazine. But first, a short summary for those who have just joined us.

I am a physicist, researcher, 25 years working on experiments with nuclear fusion at the Laboratory of Plasma Physics 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’m retired, and I can look at this whole area dispassionately, and it seems to me that a commercial fusion reactor will bring more problems than it can solve.

Therefore, I feel that I must dispel all sorts of sensations that have arisen around the topic of thermonuclear energy, which is often called the "ideal" source of energy, and present it as a magical solution to world energy problems. Last year’s article proved that all the constantly advertised possibilities of this ideal energy (usually “endless, cheap, clean, safe, free from radiation”) are broken up into cruel reality, and that the thermonuclear reactor is actually approaching the opposite of the idea of ​​an ideal energy source . But that article mainly discussed the shortcomings of conceptual fusion reactors, and proponents of this idea continue to insist that these shortcomings will be fixed somehow.

However, now we have already reached the point at which we can for the first time study the prototype of a thermonuclear power plant in the real world: the International Thermonuclear Experimental Reactor ( ITER ), which is now being built in Cadarache in southern France. Although there are still years left before its launch, the ITER project has advanced enough to be studied as a test case of a bagel circuit known as a tokamak- The most promising approach to generating 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 installation on Earth, even remotely resembling a practical thermonuclear reactor. As wrote The New York Times, this setting is "built to ensure long-held dream: that nuclear fusion, nuclear reactions taking place in the sun and hydrogen bombs, it is possible to control and produce energy from it."

Plasma physicists regard 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 to maintain plasma temperature. Such conditions require that thermonuclear energy be at least five times greater than the external plasma-heating energy. 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 will do.

Let's see what conclusions can be drawn from the fatal flaws of fusion reactors by studying the ITER project, focusing on four areas: electricity consumption, loss of tritium fuel, neutron activation, and the need for cooling water. The physical scheme of this project worth $ 20-30 billion is shown in the photo below.



Erroneous motto


On the ITER website, the visitor is greeted with a statement “Unlimited Energy” - the battle cry of thermonuclear energy enthusiasts around the world. The irony of this slogan passes by the project participants and the public. But everyone who has been following the construction of the project for the past five years - and it’s easy to follow it from the photos and descriptions on the project’s website — would be surprised at the huge amount of energy spent on it.

The site, in fact, boasts this invested energy, advertising each of the ITER subsystems as the largest system of this kind. For example, a cryostat, a liquid helium refrigerator, 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 heaviest will be the foundation and buildings weighing 340,000 tons and the tokamak itself weighing 23,000 tons.

But this should not be admired, but horrified, since the "largest" means a large investment of capital and energy, which should be on the side of the "credit" of the energy ledger. And most of this energy was obtained from fossil fuels, which left an incredibly huge “carbon footprint” in the preparation for the construction and the construction of all auxiliary buildings and the reactor itself.

At the construction site of the reactor, fossil fuel-powered machines dig huge volumes of land to a depth of 20 m, produce and pour in countless tons of cement. The largest trucks in the world (using fossil fuels) transport huge reactor components to the construction site. Fossil fuels are burned during the excavation, transportation, and processing of materials necessary for the manufacture of fusion reactor components.

You can ask how much of the energy spent on this will be able to return - but of course, it will not work to return it. But the materialization of these incredible wastes of energy is only the first component of the irony associated with “unlimited energy”.

Next to these buildings, on an area of ​​4 hectares, there is a power station with massive substations that transmit up to 600 MW of electricity from the local electric network - this is enough to power a medium-sized city. This energy will be required to support ITER's operational needs; no energy will ever go outside, since the ITER design does not provide for the conversion of thermonuclear energy into electricity. Remember that ITER is testing equipment, it will only demonstrate the operability of the concept of simulating the inner part of the Sun and connecting atoms under control; ITER is not intended to generate electricity.

The presence of an electrical substation indicates the enormous energy costs of the ITER project - and, in general, any installation for synthesis. Thermonuclear Reactors -experimental installations , and there are two types of electricity consumption. 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 between 75-110 MW, as JS Gascon et al wrote in a 2012 article for Fusion Science & Technology, “Design and Key Features for the ITER Electrical Power Distribution”.

The second type of consumption is associated with the plasma itself and operates on a pulsed basis. For ITER, it will take at least 300 MW for several tens of seconds to heat up the plasma and establish its necessary fluxes. A 400-second operating phase will require about 200 MW to support fusion and control plasma stability.

Even during the remaining eight years of the construction of the power plant, 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 consumption.

However, most of the information about energy expenditures - and the particularities that ITER will generate not heat but electricity - was lost when the project was presented to the public.

The truth about energy


The New Energy Times recently posted a detailed article, The ITER Energy Multiplication Myth, which describes how the public relations department of this installation spread poorly worded information and confused the media. A typical distribution statement looks like “ITER will produce 500 MW of energy, consuming 50 MW”, which seems to imply that both numbers describe electrical energy.

The site clearly describes that these 500 MW of output energy refers to the synthesis energy contained in neutrons and alpha particles, and is not related to electricity. And the mentioned 50 MW refer to the energy transferred to the plasma to maintain its temperature and currents - and this is only a small part of the total energy consumption of the reactor. As mentioned earlier, it ranges from 300 to 400 MW.

The criticism of the New Energy Times is technically correct and draws attention to the enormous electricity demands of any fusion plant. It has always been known that enormous energy is required to launch any fusion system. But tokamak systems also require hundreds of megawatts of electrical energy just to work.

However, there are more serious problems with the advertised work of ITER than an incorrect description of the energy consumed and emitted. Nobody argues with the fact that the installation will consume 300 MW or more of energy - the main question is whether the ITER will give out 500 MW of at least some energy. And this question concerns the vitally important tritium fuel - its supplies, the desire to use it and the actions necessary to optimize its use. Among other misconceptions is the real nature of the synthesis product.

Tritium problems


The most active fuel for synthesis will be a mixture of isotopes of hydrogen, deuterium and tritium, in a proportion of 50-50. This fuel, which is often written as DT, in neutron yield is 100 times greater than pure deuterium, but also exceeds it in terms of radioactive effects.

There is a lot of deuterium in ordinary water, but there are 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 tritium reserves”. 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. Potentially, fuel can also be obtained from Romania. Today's “world reserves” of tritium are about 25 kg, and they increase by about a pound a year, as they wrote in a 2013 article entitled “Estimating Tritium Reserves for ITER” in Fusion Engineering and Design. Tritium reserves should reach peak by 2030.

Although thermonuclear proponents happily talk about fusion from deuterium and tritium, in fact they are extremely afraid of using tritium for two reasons: firstly, it is radioactive, so there are safety problems associated with the possibility of its release into the environment. Secondly, the bombardment of the reactor vessel by neutrons leads to the inevitable receipt of radioactive materials, which requires enhanced protection, which, in turn, seriously complicates access to the reactor for its maintenance and creates problems associated with the storage of radioactive waste.

Over 65 years of research in hundreds of tritium plants, only two magnetic trap systems have been used: the Tokamak Fusion Test Reactor in my old plasma lab at Princeton, and the Joint European Tokamakin the village of Culham, UK.

Current ITER plans include the acquisition and consumption of at least 1 kg of tritium per year. Assuming that the project succeeds in finding a suitable source of tritium and has the courage to use it, will the goal of 500 MW of synthesis energy be achieved? No one knows.

The “first plasma” in ITER is due to happen in 2025. It will be followed by a leisurely 10 years of continuing the assembly of machines and periodic launches of plasma using hydrogen and helium. These gases do not emit neutrons, and therefore will solve the problems and optimize the operation of the plasma with minimal radiation hazard. Plasma instability must be kept within the framework, and it will be heated and maintained at high temperature. Therefore, it will be necessary to reduce the influx of atoms other than hydrogen.

According to the ITER schedule, it will start using deuterium and tritium in the late 2030s. But there is no guarantee that he will succeed in reaching the goal of 500 MW; to generate a large volume of thermonuclear energy, among other things, it is necessary to develop an optimal recipe for throwing in deuterium and tritium in the form of frozen balls, to support particle rays, pumping gas and processing waste. During the inevitable trial and error method in the early 2040s, the synthesis energy at ITER is likely to reach only a small fraction of 500 MW, and all tritium used will be lost.

An analysis of the use of DT on ITER suggests that only 2% of the injected tritium will burn, so 98% of tritium will come out unscathed. Although a fairly large portion 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 vessel, beam injectors, pump channels and other devices. The tritium atoms, having passed all these circles of hell several times through the plasma, vacuum, processing and power systems, will partially find themselves in an eternal trap in the walls of the reactor and its components, as well as in the plasma diagnostic and heating system.

The leakage of tritium at high temperatures into many materials is still poorly studied, as explained by R. A. Kauzi and his coauthors in the article “ Tritium barriers and scattering of tritium in thermonuclear reactors”". Perhaps a small portion of the trapped tritium can leak into the walls, and then into the channels of the liquid and gaseous coolers, it will not be possible to avoid. Most of this tritium will eventually decay, but it will inevitably enter the environment through the circulating water cooling the reactor.

Developers of the future tokamaks it is usually assumed 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 different parts of the subsystem ITER will demonstrate that the accumulation of lost tritium can exceed the volume of the burned one and can only be replaced by buying expensive tritium from nuclear reactors.

Radiation and radioactive waste of thermonuclear fusion


As noted earlier, the ITER is expected to produce 500 MW of thermonuclear, rather than electrical, energy. But what proponents of thermonuclear fusion do not tell you is that the thermonuclear energy received will not be some kind of innocent radiation like solar, 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 the bombardment of the walls reactor and its components.

Only 2% of the neutrons will be intercepted by the 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 converted into neutrons. But ITER will look like some kind of household appliance that converts 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, which dissipate energy from a collision with neutrons. In principle, this thermal neutron energy can somehow be turned back into electricity, with very low efficiency, but when developing the ITER project, they decided not to solve this problem. This task was postponed until the construction of the so-called "demonstration reactors", which thermonuclear proponents plan to build in the second half of the century.

A long-known problem of thermonuclear energy is damage to materials exposed to neutron radiation, which is why they swell, become brittle, and quickly wear out. But it so happened that the total operating time of ITER with a high neutron yield would be too short for the structure of the reactor to suffer, however, interactions with neutrons would still lead to the appearance of dangerous radioactivity in the components of the reactor, resulting in an unimaginable amount of radioactive waste - 30,000 tons

The tokamak in ITER will surround a monstrous concrete cylinder 3.5 meters thick, 30 meters in diameter and 30 meters high, called a bio shield. He will protect the outside worldfrom x-rays, gamma rays and random neutrons. The vessel of the reactor and non-structural components both inside and outside the reactor inside this bio-shield will become extremely radioactive due to neutron fluxes. More time will be required for maintenance and repair, since all this maintenance will go with the help of equipment with remote control.

About 3,000 cubic meters are expected from a much smaller JET pilot project in Britain for radioactive waste, and its cost of decommissioning is estimated at $ 300 million, according to the Financial Times. But these numbers fade before 30,000 tons of ITER radioactive waste. Fortunately, most of this induced radioactivity will disappear in a few decades, but after 100 years, about 6,000 tons of waste will still be hazardous, 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 area, as well as the final decommissioning of the entire reactor complex, are energy-intensive tasks that will even more strongly 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 thermal energy can reach 1000 MW, but even without a thermonuclear reaction the complex will consume up to 500 MW of energy, which in the end will still turn into heat to be removed. ITER will demonstrate that thermonuclear energies consume much more water than any other power plant due to the huge parasitic energy consumption that turns into additional heat that needs to be removed (parasitic refers to the absorption of the same energy that the reactor produces).

Water for cooling will be taken from the Provencal canal, diverted from the Durance River, and most of the heat will be released into the atmosphere using 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 capable of supporting the functioning of a city with a population of one million people (the daily ITER demand for water will be much less, since the reactor power pulses will last 400 seconds for up to 20 pulses per day, and the cooling water will be reused).

And although ITER produces nothing but neutrons, its maximum coolant flow will still amount to almost half the flow of a really working station, burning coal or nuclear fuel, and generating 1,000 MW of electrical energy. At ITER, pumps that pump water through 36 kilometers of cooling pipes will consume 56 MW of energy.

A large fusion station like ITER can only work in places like the French Cadarache, where there is access to many powerful power lines and a 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 gigawatt thermoelectric power stations. Given the reduced availability of fresh water and even cold ocean waterThe difficulties in supplying coolant in themselves will make the widespread use of fusion reactors impractical.

ITER Impact


ITER will work well or not, its main legacy will be an impressive example of many years of international cooperation between 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 power plants, the construction of which was allowed in recent years in the United States ( Wi-Si Summer and Vogtl ) [Westinghouse was supposed to build the 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, while transporting a new 300-ton nuclear reactor for the Vogtl nuclear power plant manufactured in South Korea by rail to the USA, the platform with it seriously tilted, almost to the ground. However, the reactor was not damaged. / approx. perev. ] and in Western Europe ( Hinckley and Flamanville) [excessive cost of the Hinckley project called into question its completion; Over the past six years, two accidents occurred at the existing Flamanville NPP (without environmental consequences), and the cost of building a new unit has already tripled compared to the initial one, while construction continues / approx. perev. ], as well as the MOX nuclear fuel project in the US Savannah River region [ next to the nuclear repository / approx. perev. ]. All these projects experienced a tripling of the cost of construction, and the construction time increased by years and even decades . The main problem is that all nuclear power plants - whether synthesis or decay - are extremely complex and prohibitively expensive [ construction of two power units of the first stageThe Tianwan NPP , which Rosatom was building for China, cost $ 3 billion and took 11 years. The third power unit was built in 5 years / approx. perev. ].

The second invaluable role of ITER will be its impact 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 of the ITER power plant, it will obviously be a neutron-emitting and devastating source of tritium fed by nuclear reactors, consuming hundreds of megawatts of electricity from the local grid and requiring unprecedented volumes of water for cooling. Damage due to neutrons will intensify, and the remaining characteristics will remain the same in any subsequent thermonuclear reactor, created in an attempt to generate enough electricity to exceed its own needs.

Faced with such a reality, even energy planners with the brightest glowing eyes 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 flaws prevented another imaginary source of “unlimited energy” from appearing and dominated light water reactors [ breeder reactors operate in Russia, and in two years a new unique lead-cooled fast neutron reactor will be built / approx. perev. ]

Also popular now: