Do we actually need fusion energy at all?

EFDA - wo, 08/11/2017 - 12:16

Will it be possible to use just renewable energies to reduce the world‘s fossil fuel consumption? Could fusion power help to reduce the world’s CO2 emissions? Sometimes the simplest questions are the most important – and the most difficult – to answer. A small excursion into recent energy problems and cutting-edge energy predictions may help to put these questions into the right focus and to provide proper answers.


My grandparents generation will probably be remembered as the one that experienced the most incredible changes during their lives: they were born in a society where phone boxes were the only way to make calls, where travelling was a luxury reserved for the rich, where clothes were washed only by hand. Now, their generation uses mobile phones, travels by plane and owns washing machines. The changes that my grandparents have experienced during their lifetime are not without consequences for our society. The world energy consumption has grown enormously in the past 90 years, increasing to seven times that of 1930. This dramatic jump is not only related to the population growth. The world’s per capita energy-consumption has doubled the value from 1930: hence, our life-style has become much more energy-consuming in a very short period of time.


To satisfy this thirst for energy, fossil fuel consumption was increased dramatically. Coal, oil and natural gas rapidly began to dominate the energy market. Now everyone is familiar with the effects of this “energy revolution”: the increased emission of greenhouse gases is affecting the natural environmental balance that has ruled on Earth for more than 100,000 years. A relentless global warming process is causing the ice to melt and the climate to change and has resulted in disastrous impacts on our lives. At the same time, the concentration of fossil fuels in few regions (Middle East, Russia etc.) is seriously undermining geopolitical stability. Hence, a society with low fossil fuel consumption has become a fundamental goal that must be achieved in order to restore the world‘s natural and geopolitical stability. The Paris agreement of 2016 is pushing towards this aim, even if it has some limitations.


The 2016 Paris Agreement is a major international accord on tackling climate change, supported by almost 200 countries. It aims to restrict the global average temperature to less than 2° C above pre-industrial levels, mainly by way of cutting greenhouse gas emissions. 2° C is seen to be a tipping point, beyond which irreversible climate changes will occur, leading to a devastating rise in sea levels, extreme droughts and wildfires. Fusion could provide an essential source of zero emission energy needed to achieve the goals of the Paris Agreement.


In this context, renewable energies play a crucial role. Wind farms, solar panels, biomass, geothermal and hydro power plants represent valid energy sources that can help to reduce fossil fuel consumption. Nevertheless, a socio-economic study of EUROfusion published in 2016 estimates that by 2100 renewable energies will cover 68 % of the total electricity production, while 21 % will still be provided by fossil fuels and 11 % by nuclear fission. This scenario sets low CO2 emission targets, a condition that is helping the penetration in the market of renewable energies and does not consider fusion energy to be an option at all. Hence, it seems clear that renewable energies alone will not be able to completely conquer this energy transition.


The same EUROfusion socio-economic study also analyses a different scenario, one which considers a drastic reduction of the world per capita energy consumption, a low CO2 emission target and the first fusion power plant connected to the grid to be in operation by 2070. Considering that we are talking about developments that may be implemented in 50 years’ time, we should always be cautious with such timelines. Nonetheless, this study has interesting results: it predicts that, in 2100, 75 % of the total electricity production will be generated by renewable energies, 14 % by fusion power plants, 6 % by nuclear fission and only 5 % using fossil fuels. These estimations are telling us something quite intuitive: if we will bring about a drastic reduction of our per capita energy consumption, if we aid the development of renewable energies and if fusion power plants are able to start operating soon enough, the energy transition could be achieved fully by 2100. Fusion energy, then, would not be a childish tantrum of stubborn scientists that do not want to throw in the towel, but it seems it will be necessary in order for our society to restore the world‘s natural and geopolitical stability.

I am a former student of the European Master of Science in Nuclear Fusion and Engineering Physics and I recently started a PhD at the Max Planck Institute for Plasma Physics in Garching. As an energy engineer, I believe that engineers should develop “appropriate technologies” for mankind. Fusion is one of these, since it may help to reduce CO2 emissions and the high fossil fuel dependency of our society, as I explain in my article.

Davide Silvagni (24) from Italy is currently based at: Garching, Germany. (Picture: private)

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Putting planet earth first?

EFDA - wo, 08/11/2017 - 12:15
Revisiting the debate about the future of Germany’s energy supply

The future scenario in Germany appears obvious: Renewable energies are to be expanded and conventional power stations are to be closed down. Simply add on a few storage systems and power grids and the German energy transition is complete – but is it really that simple?


For decades, the German population has feared nothing more than a nuclear disaster. After the Fukushima accident Chancellor Merkel and her government finally decided to close down all of the remaining nuclear power plants within eleven years. But climatologists have been warning us about climate change since the early 70s. As a result, the government has also been forced to develop a plan designed to help decrease CO2-emissions until 2050. As a consequence of this, and in order to reduce greenhouse gases, Germany has also decided to shut down its fossil fuel power plants.


Germany’s energy mix before Fukushima and now. The red component represents the climate impact of each source. (Based on www.energy-charts.de and VDI 2007)

Now the country has to fight a battle on two fronts. Renewable energies primarily replace another CO2-free one, viz. nuclear, while the use of fossil fuels decreased slightly (see Graphic). This is one of the reasons why it is very probable that the next climate change goal in 2020 will not be met. Additionally, in order to compensate for the remaining nuclear power plants, Germany must theoretically double its wind power capabilities. To achieve these aims, the rate of expansion of renewable energy had to be about one order of magnitude larger (see www.energy-charts.de).


Is it possible for Germany to be fully powered by renewable energies by the end of this century? There are a few optimistic, yet non-reviewed studies, like Greenpeace’s “Plan B” or “Kombikraftwerk2” produced by the Agency of Renewable Energies. They predict that it can be achieved by way of relatively small efforts, by installing plants, storage and backup systems. Anyhow, most of these studies have critical issues: they ignore, for example, changing weather conditions or assume an unrealistic decrease in the amount of energy consumed. I propose to consider the calculations made by Fritz Wagner, retired German plasma physicist and former director at the IPP. He has generated simulations for a fully renewable supply that also takes into consideration sector-coupling or an international power grid. Even in the best case scenario it is more likely that Germany will need to multiply the level of power generated from renewable sources by ten or twenty times the current rate. Wagner also warns about the underestimation of dimensions of storage systems and their operational limitations.


The famous banner of the anti-nuclear movement at a protest-camp against coal mining near Cologne, Germany in 2017. Is it in times of climate change still legitimate to reject nuclear fission and fusion?

About 71 % of Germany’s population (according to an Emnid study from 2017) agrees that climate change is one of the biggest threats to today’s society. But in 2016, 70 % of Germans also wanted to avoid nuclear fission according to a study from YouGov. Fusion seems fascinating but does not play a major role: for example, when Wendelstein 7-X created its first hydrogen plasma in 2016, fusion was a trending topic in the German news for about a week. However, in the government’s declaration on the energy policy, fusion is not even mentioned.
So, nuclear power of any kind appears to remain something of a hot potato in this country. In most cases, it is only associated with potential risks and nuclear leftovers. The contradiction between phasing out nuclear power and attaining climate goals is often downplayed by politicians, independently of their party membership (see both the government‘s declarations and the party programmes of CDU, SPD, Alliance 90/The Greens, The Left). Meanwhile, the European Union is keeping its nose out of this struggle. The Parliament in Brussels has declared that each country is free to choose the method of supply it prefers, just as long as the EU member states accomplish the international climate goals.


Given the problems explained above, I think, we need to embark upon a renewed debate of Germany’s energy future. In an unbiased discussion, we need to figure out an energy mix that will minimise the risks for both humans and the environment. I personally have come to the conclusion that we initially should focus on phasing out the use of fossil fuels for power. Nuclear power will be necessary as long as the problems of pollution are as present as they are today. I know that continuing to use nuclear as a source of power will be a tough decision. The full argumentation would explode beyond the scope of this article. In the long run, nuclear fusion should, together with renewable power, play a crucial role. It may be able to supply the growing energy demand world-wide much more adequately than a complex system based ONLY on renewable sources. Anyway, we must accept that fusion will not help us to reduce the CO2 emissions before 2070 or even later. Though emissions have to be rapidly decreased already in the coming years, if we want to succeed in stopping climate change. Fusion can help in the longer run to meliorate the two major disadvantages of wind energy and Photovoltaics, which is low power density and intermittency.


On the other hand, we might also stick to the current strategy, which means: we continue to hope that sometime within this century renewable energy will be sufficient for our needs. However, if we are to fail, the result would be a simple one: the power supply, even that of 2100 will be a dirty and noxious one, if sufficient at all. That would be putting “Planet Earth last”.

I am a student of Physics and I will be initiating my master’s thesis in fusion research by the end of this year. I intend entering into the theoretical fields, because he mathematical description of nature has always been an interesting challenge. For me, convincing society of visions of a sustainable future is more exciting than maths itself. That’s why I have enjoyed debating this topic even since my days at school.

Fabian Wieschollek (23) from Germany is currently based at: Garching near Munich, Germany, fb.me/Fabian.Wieschollek. (Picture: private)

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Proliferation: preparing early

EFDA - wo, 08/11/2017 - 12:14

The prospect of a fusion power plant is edging closer to reality. Work is underway to ensure that these plants will be designed to mitigate low-level proliferation risks.


The breakout scenario has long been a concern for the international community but it’s never been a major concern when it comes to fusion research. There simply haven’t been significant levels of fertile material in fusion. However, with fusion power plants looming on the horizon, the risk calculus will change. Research and development is now underway to mitigate these low-level risks.


As the largest fusion experiment on Earth, ITER will test breeding blankets for the production of tritium. One future breakout scenario involves a state that introduces fertile material to the breeding blankets. However, not only would doing this have implications for the tritium breeding ratios – every cubic centimetre counts – but it would alter the power consumption of the plant and the detectable signatures of the tritium. Both of these changes can be tracked by satellites using current technology and the presence of fertile material would quickly be discovered.

Another breakout scenario is the introduction of fertile material into the coolant flow. Again, this scenario can be mitigated by monitoring changes in background radiation. While further research and development is required to confidently mitigate this risk, there is plenty of time left to do so and ITER will provide the perfect opportunity.

There is an awareness of the risks, they’re managable and the international community is taking steps to anticipate them.

Dr Richard Kamendje from EUROfusion, who previously dealt with proliferation issues at the IAEA, anticipates that over the coming decades the international community will need to incorporate some safeguards to mitigate the low-level risks in fusion.

Dr Richard Kamendje, Responsible Officer of the EUROfusion ITER Physics Department, Picture: EUROfusion


New designs for nuclear power plants are sent to the IAEA for approval and must incorporate safeguards in the designs. While there are no current designs for fusion power plants, there is little doubt they will go through a similar process. The next 20 – 30 years will see the research, development and design of such reactors. At each step along the way, the long-term low-level risks will be known and planned for. ITER has enabled international scientific collaboration on a scale that has rarely been seen before. This stands in marked contrast to competitive nuclear weapons research and the construction of their supporting facilities. Careful and considered research over the coming decades will ensure that fusion remains the low-level proliferation concern it always has been.

I am interested in communicating how emerging technologies reshape the world and challenge the status quo. Fusion power will do away with the limits of energy supply and fundamentally rewrite our understanding of power generation. Though this is not without risk, the risks are minimal and need to be communicated before they are misunderstood.

Thom Dixon (28) from Australia is currently based at: Macquarie University, Sydney, @thomdixon. (Picture: private)


Fusion boosted bombs fuse deuterium and tritium as a trigger to spark lots of early neutrons, which chain-react to make the primary fission explosion more efficient and about twice as powerful. This is a relatively simple weapons technology, and it is suspected that North Korea currently have this type of bomb. A pure fusion bomb is a hypothetical weapon. In comparison with fission fueled bombs, weapons using 100% deuterium-tritium fuel could more easily evade current non-proliferation measures.

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ITER: the great fusion endeavour

EFDA - wo, 08/11/2017 - 12:13

It has been said that the nuclear fusion conundrum will be solved within 30 years … but they have been saying that for the last 50 years already. Now, we humbly expect the first feasible fusion power plant prototype to start operations sometime in the 2060s. Producing electricity from fusion is the greatest engineering and scientific challenge of our century. A scientific journey that is greater than achievements such as the building of the Great Pyramids or the Great Wall of China, or landing on the Moon … and this time, humankind depends on it.


Mark Henderson

Our use of fossil fuels has an accelerating countdown timer. Either we completely deplete our available reserves or we damage the environment just enough to prevent human society from continuing as we know it. We have to find alternative sources of clean energy, whatever they may be. As the head of the Electron Cyclotron Section of ITER and advocate of fusion energy, Dr. Mark Henderson, puts it: ”We are addicted to carbon. We have to prove, as a species, that we are collectively intelligent enough to prevent our own extinction.” Fusion looks like a promising answer.

We are addicted to carbon. We have to prove, as a species, that we are collectively intelligent enough to prevent our own extinction.

Dr. Mark Henderson


Fusion power plants will create artificial stars and become the clean energy source that will power our way of life in the future. But we are not quite there yet. At the moment, it takes a lot of energy to confine the plasma and a lot more to heat it up to the temperature required for fusion to occur. At this time, we are building ITER to prove that we will be able to obtain a net gain of energy output from a fusion reaction, sometime in the next 20 years. Then, DEMO, a prototype power plant, will be built in order to transform the excess output fusion energy into usable electricity, based on everything we learn from ITER.

As fusion scientists we have the chance to impact the future of the hundreds or thousands of generations to come.

Dr. Mark Henderson


The tokamak pit of ITER some years ago. Pictures: Eyesteelfilm

Generations of scientists have dedicated their whole careers to fusion research, but there is still a long way to go. The end goal is so far into the future that those who finally make fusion happen may not have even been born yet. The tens of thousands of scientists and individuals working towards fusion today are well aware that they might not be remembered in thirty or forty years, and that is okay. Believing in fusion is looking beyond the importance and the lifetime of our generation. Mark presumes that “as fusion scientists we have the chance to impact the future of the hundreds or thousands of generations to come.”


Nuclear fusion is the epic scientific quest of our time. “We have to face the fact that fusion is extremely complicated”, warns Mark. “We need to orient the scientific community and the opulation towards it. Otherwise, look at the consequences”. Fusion is one of our best hopes, as a species, to have a sustainable and reliable near-limitless source of clean energy within the 21st century. “I believe we will have multiple clean sources of energy in the future: solar, wind – but fusion will be the basis”, says the ITER expert.

I am an electronics engineer currently doing a PhD in the Advanced Plasma Science and Engineering programme. I develop microwave reflectometry diagnostics that aid other physicists understanding plasma behavior in nuclear fusion research. I advocate for Open Science and thank EUROfusion for the support in publishing Open Access.

Diogo Elói Aguiam (27) from Portugal is currently based at: Lisbon, Portugal, @diogoaguiam, https://daguiam.github.io, https://www.linkedin.com/in/diogoaguiam/. (Picture: private)

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Building the future with S.T.E.A.M.

EFDA - wo, 08/11/2017 - 12:12

There is a great demand for technically skilled people in our information-driven society. S.T.E.A.M., an acronym that stands for Science, Technology, Engineering, Art and Maths, is an interdisciplinary approach to learning. Being both physicists and robotics instructors, we decided to launch a project for young enthusiasts, specifically including girls, who are traditionally underrepresented in the sciences.


In the end, we achieved our aims, we have prepared the next generation of innovators. By teaching science and technology literacy, we have increased the level of interest in all those who might, one day, wish to work in fusion or other future-relevant subjects.


The Ev3storm roboter is one of the models the school children learned to programme. Picture: The Lego Group

“Transformers visit my school” is a scheme designed for primary and middle school pupils. With the help of Lego Mindstorms robotics kits, the children have learned how to design and construct a robot, attach sensors, think in terms of algorithms and program the tiny machine. The partakers even approached difficult scientific concepts, such as the physics of sensors, more easily. Hands-on activities are used to fill the gaps left by traditional education methods. Our participants enjoyed their practical challenges including building, testing, programming and troubleshooting. They worked excitedly and creatively and let their team spirit guide them. Our role, in the meantime, was to mentor and lead them, allowing the young engineers to take their own initiatives and creative risks, and to explore their different levels of expertise and imagination. We discovered that the satisfaction of accomplishment was a further motivation to the teams. They finally realised that science is everywhere and ready to be discovered!


Nowadays, success results from what we are able to do with knowledge acquired. Hence, in addition to preparing our future workforce, it is essential to spread the benefits of S.T.E.A.M. education. Engaging children from an early age in special processes, enables them to cultivate and capitalise on their own interests and, moreover, their curiosity. By watching them confront the technical difficulties with the Lego robots, we understood how they learned to investigate. “I enjoyed that we worked as a team in the Robotics First Lego League in Greece. Everyone had a distinct role, but we needed to collaborate and share our ideas in order to complete the tasks”, says nine year old Eudoxia Karlati-Koufopoulou Another fascinating aspect was that ignorance aids learning and further improvement. By this we mean, failures are considered to be part of the discovery process thus leading to a better approach. “I learnt to take risks. I evaluated my constructions and improved them”, states Lucas Lenard, a sixth grade primary student.

I learnt to take risks. I evaluated my constructions and improved them.

Lucas Lenard


Can there ever be a connection between Art and S.T.E.M.? According to Leonardo Da Vinci, we need to “realise that everything connects to everything else”. Those additional skills make sciences applicable and innovative in real life. Mathematical concepts such as spatial awareness or geometry are easily approached by art while cultivating a basic scientific tool: the power of observation. Children become open minded and quickly assimilate new ideas.

According to Leonardo Da Vinci, we need to “realise that everything connects to everything else”


As was mentioned earlier, it is not news that girls are underrepresented in scientific and technological fields. This will have an impact on the future staff pool. Young women are often engaged in traditionally “girly” stuff. Early intervention with S.T.E.A.M. subjects encourages them to participate. Our project boosted the self-confidence of female participants as they took on the technical challenges. We realised that when girls overcome their fear of failure or non-qualification, they even gear up. In many cases, they were chosen to be team leaders during our competition. In summary, it is important that these positive projects do not remain single events only. Key influencers, such as parents, teachers and specifically women-leaders should further encourage girls to continue in technical fields.

Key influencers, such as parents, teachers and specifically women-leaders should further encourage girls to continue in technical fields.


Technical education can be applied widely and creatively in order to overcome stereotypes. Working practically with children and encouraging them to explore, enables them to gain a deeper understanding of technological fields. Science has simply become more relevant to them. Indeed, our pupils gained additional skills. They finally realised that S.T.E.A.M is a key way to make their own and others’ lives better”.

I am an undergraduate physicist and a Robotics instructor. Wanting to pursue a career in fusion, I believe that the answer to the question of safe and clean energy is written in the stars! Fusion and its attractive prospects promises a better future, so I would like to participate in the diffusion of this effort.

Irene Papa (28) from Greece is currently based at: Athens, Greece. (Picture: private)

I am a physicist and my field of expertise is Medical Physics. I have been fascinated by the subatomic world and the power of the nucleus. Fusion is a great example of this power and I think we all must corporate in order to achieve the promising future of vast and clean energy.

Nikos Moraitis (30) from Greece is currently based at: Athens, Greece. (Picture: private)

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The need of the hour: nuclear fusion

EFDA - wo, 08/11/2017 - 12:11

As a child, I witnessed innumerable incidents of load shedding in Delhi, especially during summers. This meant no electricity at home and studying by candlelight for hours. Even today 24/7 power supply remains a dream that is unfulfilled. Just imagine, there are around 396 million people with no access to electricity in India! Around 75% of the world population is living in developing countries with energy demands that are expected to surpass that of developed nations in the next 50 years. My big question is: “How do we tackle this energy crisis?” We will be running out of non-renewable resources in the next 40 to 80 years. But, coal, oil and natural gas currently supply most of the world’s energy.


Inside the stellarator Wendelstein 7-X. Picture: Christophe Roux/EUROfusion

The general scepticism about nuclear energy is well known. Like most countries, India has also witnessed raging controversy regarding the suitability of nuclear power as the solution to ever growing energy requirements. I too was drawn into this debate and thus developed a strong desire to contribute something towards the promotion of clean and abundant energy. It engendered in me a deep interest in nuclear physics and engineering. It was only during my master’s studies that I understood in-depth the prospect of employing fusion power as an almost inexhaustible source of energy for future generations. Now, I am proud to work at one of the most developed fusion experiments in this world: the stellarator Wendelstein 7-X (W 7-X).


Fusion reactions take place at high temperatures of around 10 keV (~100 million Kelvin) where the fuel is in a fully ionised state, also called plasma. The particles have a large thermal velocity with a tendency to escape from the machine. Hence, some method of confinement of particles is essential. Magnetic field confinement using high powered magnets is one of the solutions. Tokamaks and stellarators, two types of fusion experiments, are both based on this concept.


In the past, research into stellarators has been overshadowed by interest in the other concept, the tokamak. However, recent advances in computational power and engineering expertise have revived it. So, the inauguration of Wendelstein 7-X (W7-X), the world’s newest stellarator, has put stellarator research back on the fusion table.

See also the article “A snowflake for fusion?” by Carrie Beadle.

A recent publication in Nature Communication, by Prof Thomas Sunn “from my institute”, the Max Planck Institute for Plasma Physics, highlights the success achieved in W7-X. Sunn Pedersen discussed how he and his colleagues managed to tackle the challenges.


Picture: private

The main obstacle in reaching high powerdensity in fusion devices is the limited capability of the divertors. Divertors are the ashtrays of fusion experiments and need to withstand immense heat and particle loads.
My present goal is to develop of special magnetic configurations that should help to manage the heat flux. They will be tested in an operational campaign in W7-X. This should further assist us in comprehending the impact on the exhaust physics in a stellarator. Once the riddle of tackling the tremendous power exhaust from fusion plasma has been solved, we will have moved one large step closer to a fusion power plant.


The previous operation phase of W7-X has concluded in March 2016 and delivered promising results. We found parameters, for example, for plasma temperatures and densities, that enhance the performance of a stellarator plasma, exceeding predicted values from simulations. There is, of course, still a lot of research that must be done before nuclear fusion becomes a viable commercial option. Nevertheless, I feel like I am participating in the creation of the future solution for the demanding energy needs of the world. Fusion will, I hope, one day create energy for everybody.


Tokamaks are the most well developed reactor type due to their simple flat magnetic coil design. They have an induced electric current that confines particles on a helical path, but this current also means pulsed operation and results in unwanted instabilities. Stellarators have a complicated twisted coil design, which has been made possible thanks to modern computer modelling. These twisted coils produce a natural helical path thus avoiding the current instabilities and resulting in a much desired steady-state operation.

I am a PhD student, but also a science enthusiast with a passion for writing. I believe that nuclear fusion undeniably holds the key to solving the current global energycrisis. EUROfusion presents a perfect platform for young researchers like me to speak out and dispel the misconceptions as well as raising awareness about nuclear fusion amongst the general public.

Priyanjana Sinha
(25) from India is currently based at: Greifswald, Germany. (Picture: private)

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A snowflake for fusion?

EFDA - wo, 08/11/2017 - 12:10

A snowflake might not be the first thing you associate with a hot fusion plasma. But it is a concept designed to handle the heat where the plasma touches the vessel wall. It is not surprising that this task presents technical difficulties. However, the scale of the problem is remarkable: the predicted heat load on the ITER targets is greater than that on the soil beneath a launching rocket!


Two of the biggest scientific and technological challenges facing ITER and DEMO are associated with plasma-wall interaction. Firstly, how to minimise the heat load on the target plates. Secondly, how to prevent impurity particles from entering the core plasma and causing heat loss. For this reason, such troublesome particles should be kept to a finite, well-defined area.


Early tokamaks achieved this aim using a limiter – typically a rail extending a short way inwards from the inner wall of the tokamak. In this configuration, it is relatively easy for the impurity particles to re-enter the core plasma. A solution was proposed as early as in the 1950s, split the flux surfaces at a certain point. The field lines will cross each other and end at two divertor plates, some distance away from the last closed flux surface, keeping the core plasma “safe and clean”. However, it wasn’t until the 1980s that this more complex configuration started to be used in fusion devices.

Limited vs diverted configuration. The limited configuration is shown on the left, with the limiter itself in blue, last closed flux surface in bold red and flux surfaces in red. On the right is the diverted configuration, with the target in blue and magnetic surfaces as before. Snowflake flux surfaces on TCV.


The diverted configuration also tackles the tremendous heat load problem. No material would be able to withstand such harsh conditions. The greater distance between the target and the flux surface allows density and temperature gradients to form along the magnetic field lines, thus reducing the temperature at the target to well below that in the core. The heat load can also be reduced by either spreading the same total heating power over a greater plate area, or by radiating more heat before it reaches the target. This requires a strongly radiating “cushion” of dense neutral gas between the target and X point. It remains very difficult to simultaneously reach the detached regime for the targets and maintain the high-confinement mode, which optimises the core plasma performance.


ITER must operate in both high confinement mode and the detached regime. The challenge is to maintain the detachment front in a stable way. It is here that the shape of the flux surfaces close to the target becomes important. So, we need a new concept: advanced divertors. These are magnetic configurations in which there is not one but two magnetic X points. The second X point modifies the angle at which the field lines arrive at the target as well as the change in separation between the flux surfaces as they approach the target. Current experiments are trying to find the magnetic field which provides the most effective heat load reduction.


One such advanced configuration is called the “snowflake”. It is named after its 6-fold symmetry, achieved by a secondary X point close to the primary X point. Researchers have discovered that this reduces the heat drastically. The area that receives the heat becomes much larger. Also, the distance along a field line from the X-point to the target is now longer, allowing a much greater drop in temperature along the line. It is clear that we need to understand the effect of divertor geometry on the heat load. Theoretical modelling of diverted geometries is just beginning, but already there are hints that first principles models can recover results of experiments such as those carried out on Tokamak à configuration variable (TCV). The Swiss Tokamak à configuration variable (TCV) from above. So, watch this space!


A divertor is the in-built vacuum cleaner of a fusion reactor and is situated along the chamber floor. Build-ups of helium ash and impurities in the plasma must be removed during operation. These heavier particles are pushed to the edge of the plasma by centrifugal forces, where they escape through a specially designed magnetic “gap” at the bottom of the plasma and fall into the divertor. The divertor shape and materials are also constructed to bear the brunt of the heat load from the plasma, thus protecting the surrounding walls.

I am a PhD student studying plasma turbulence in the outermost region of the tokamak via numerical simulation. I find fusion plasma physics exciting because it has so many different aspects, challenges and problems to be solved! My article is about the problem of overheating materials where they interact with the plasma and how we can change the magnetic field configuration to keep vessel walls from melting.

Carrie Beadle (23) from U.K. is currently based at: Swiss Plasma Center, Lausanne. (Picture: private)

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Total Eclipse

EFDA - wo, 08/11/2017 - 12:09


I‘m a chemical engineer in the commercial fossil fuels sector and fascinated by fusion, science, industry and history. Not only technologies but engineering careers will need to evolve in order to develop industrial fusion. I hope that humanity will succeed in this great journey of creating universal and balanced access to energy.

Luiz Trevisan (34) from Brazil/Italy is currently based at: Houston. (Picture: private)


As they say, ‘A picture speaks a thousand words’. Keeping this quote in mind I worked as illustrator for this edition of EuroFUSION too and tried to convey technical stuff through a comic strip to make it lucid. This was my second year with EuroFUSION team, I wish the bond strengthens. I thank Anne again to give me this opportunity. Cheers!

Amita Joshi (28) from India is currently based in: Germany. (Picture: private)

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Domesticate the fire: a crucial step towards fusion energy

EFDA - wo, 08/11/2017 - 12:08

Fusion energy is created by merging two atoms in a very hot gas, called plasma, with temperatures around 150 million Kelvin. You could surely call this a fire. This extreme scenario takes place in a reactor with a doughnut-like geometry, called a tokamak. Plasma-surface interactions pose one of the biggest obstacles for fusion experiments. The future reactor wall materials have to withstand incredible heat and particle fluxes. Scientists are currently investigating plasma scenarios in which the wall loads are more benign. One way to cool the plasma down is by means of impurity seeding.


The particles and heat flux coming from the plasma core are channelled downstream along magnetic field lines to a region called the “divertor”. Divertor targets must withstand power fluxes in the order of several MW/m2 in steady state conditions, and up to 1 GW/ m2 during intrinsic instabilities of the plasma. This is comparable to the friction that occurs during re-entry of a spacecraft into the Earth’s atmosphere. This holds true just for the steady-state regime, while plasma instabilities can lead to a hundred times the expected power loads of the plasma during ~0.5 millisecond.

Renato Perillo (right) in the control room. Picture: private


Since the early ‘80s, scientists have been trying to reduce the heat flux on the target by increasing the gas pressure in the divertor region. The plasma is cooled down throughout its path to several thousands of Kelvin due to radiation, momentum transfer and volume recombination processes. In this way, the heat loads become sustainable for the material. This phenomenon is called “plasma detachment”. In order to fundamentally understand detachment and PSI in a tokamak, various disciplines, such as material sciences, control and mechanical engineering, plasma physics and chemistry have to work together properly.


The linear plasma machine Magnum-PSI, located at DIFFER (Eindhoven, NL), is capable of mimicking the plasma-surface interactions foreseen for ITER. The excellent diagnostics accessibility provides accurate insights into the mechanisms occurring in both the exposed material and in the plasma located in the vicinity of the target.


Experiments in tokamaks over the course of the last two decades have shown that the injection of gas (so-called impurities) into the divertor region leads to an enhanced detachment. At DIFFER we are currently pursuing such experiments. In particular, we are investigating the influence of nitrogen seeding on a hydrogen plasma, focusing on the plasma chemical processes occurring in such scenario. So far, experiments and numerical simulations deliver promising results while achieving a more comprehensive understanding of plasma detachment in a fusion reactor. In the end, this will be a key factor in making this technology feasible within the second half of this century.


A fusion plasma is an extremely hot electrified gas which naturally wants to expand. It is suspended in a strong magnetic field designed to keep it from touching the chamber walls. As the temperature and pressure builds, the plasma forms areas of increasing turbulence, called instabilities, that must be controlled. There are many different types and sources of instabilities that may cause plasma disruption. The worst instabilities are able to eject streams of hot plasma out of the magnetic confinement, severely eroding the wall materials.

I am a driven PhD student working within the Plasma Edge Physics and Diagnostics group at the Dutch Institute for Fundamental Energy Research. I combine numerical simulations with experiments, addressing the issue of power exhaust in a fusion reactor. I do believe fusion energy is the most promising energy source for the future. Working day by day in such a stimulating environment is the best thing that could have happened to me.

Renato Perillo (27) from Italy is currently based at: Differ Institute, Eindhoven (NL). (Picture: private)

The post Domesticate the fire: a crucial step towards fusion energy appeared first on EUROfusion.

The story of sabotage: the tungsten investigation

EFDA - wo, 08/11/2017 - 12:07

How special forces combine to catch plasma killers


It had all started well. We managed to heatup the reactant in order to make the expected fusion reaction happen: in this case, deuterium, an hydrogen isotope. We initiated a current into the tokamak, that strange doughnut-shaped reactor. Very strong magnetic fields are used to ensure that hot particles don’t touch the inner wall of the tokamak. Finally, we were very pleased when we witnessed that the deuterium started to warm up, became ionized and converted into a gas called plasma. Ion and electron temperatures were increased successfully in the centre of the plasma, up to 150 million Kelvin. Fusion is happening right now. So far so good.


There are about twenty people glued closely to the screens in the control room. One of us, the pilot, makes the decisions. He or she watches the live footage from inside the tokamak. All of the plasma parameters had been finely tuned before the experiment started. Now the plasma control system manages everything automatically. The pilot is simply in charge of the emergency button to immediately stop the operation in the event the machine may be damaged. Meanwhile, another part of our team is responsible for monitoring the experimental signals from previous experiments. But suddenly, the core temperature starts to drop. This is exactly what we don’t want: a decline in the plasma temperature! This surely would kill the highly desired fusion reaction. Immediately, the system responds and increases the central heating function. But the temperature keeps dropping. Within a couple of seconds, the plasma dies, releasing enough energy to damage the walls. The camera shows a sudden light, like a flash, then it all goes dark. In the control room, nobody speaks. Wordless question marks hang in the air. Something went wrong. What happened?


Fusion experts like us measure several plasma parameters: current, temperature, density, radiation. In this instance, the radiation emitted by the plasma had increased over time. This is the signature of one suspect: Tungsten, or W. We know where this tungsten comes from, a special area called the divertor. It is designed to receive a lot of energy. is called integrated modelling. It is a very complex and sensitive tool. Simulating just a few seconds of plasma can take days, or weeks, depending on the level of complexity.

More on divertors: see also the article „A snowflake for fusion?“ by Carrie Beadle.

More on Tungsten: see also the article „Making ths reactor wall smarter“ by Janina Schmitz.


As a result, we have to gather our Special Forces, a team made up of experts with various scientific backgrounds in order to finally catch the saboteur and to figure out its modus operandi. This is what fusion and the realisation of fusion energy is about. We, as scientists, are dealing with phenomena that have not yet been investigated. We are pioneers … and, more often, even detectives.

Tungsten is a popular fusion material because of its high temperature resistance and its low erosion rate. Unfortunately, some erosion is still caused by the energy that ends at the divertor. W enters the plasma, but is so heavy it does not get fully ionised. This means that not all the electrons are torn away from the nucleus, and that causes W to radiate. And W is the only species in the tokamak that has this property: it has to be the material used.

The W investigation, allegory, Cartoons: B. Simony


So now, we have found the saboteur. And we have to stop it. To prevent this situation from occuring again, we simply must understand how tungsten managed to radiate so much that it made the plasma collapse. We decide to reconstruct the timeline of W impurities, just like in a police investigation. First, we gather together the information we have about the temperature, density and rotation profiles, radiation levels, and especially the radiation distribution in the plasma.

Aha, here is our first important clue: the radiation first appeared at the edge of the plasma. But after a couple of seconds, all of the emitted radiation is derived from the centre of the plasma. This means that W travelled from the edge to the centre. And this is what has caused the core temperature to drop and the plasma to collapse. But how did W travel through the plasma? W was transported, W had accomplices.


The measurements are necessary to reconstruct W’s time evolution, but not sufficient to figure out the transportation of W. We need to use another tool: simulation. The W transport obeys known mechanisms and equations. Informatic codes have implemented these. The inputs are W‘s accomplices, the Persons of Interest: temperature, density and rotation profiles. The outputs are the coefficients that quantify how far and how fast W is transported. But W also impacts the evolution of temperature and density,and radiation as we have seen before. There are many feedback loops to be simulated if we wish to reconstruct the modus operandi. The combination of several codes is called integrated modelling. It is a very complex and sensitive tool. Simulating just a few seconds of plasma can take days, or weeks, depending on the level of complexity.


As a result, we have to gather our Special Forces, a team made up of experts with various scientific backgrounds in order to finally catch the saboteur and to figure out its modus operandi. This is what fusion and the realisation of fusion energy is about. We, as scientists, are dealing with phenomena that have not yet been investigated. We are pioneers … and, more often, even detectives.


Materials inside a fusion reactor must be able to operate for a long time under neutron bombardment and hot plasma attack. Tungsten is the most promising material for use as plasma facing components. Tungsten is a robust, rare, metal chosen for its very high melting point (3422 °C), low tritium retention, and low erosion rate. However, even relatively small amounts of eroded tungsten dust are able to poison the plasma, cool it down and cause a disruption, which may result in serious damage to the machine.


In four months I will finish my PhD in nuclear fusion (hurrah!). I believe that fusion is capable of solving the energy crisis and I want everyone to know about it. A teacher once told me “If you can’t explain your job in a way that anyone can understand, then you don’t understand it yourself”. Writing about fusion in an accessible and illustrated way is challenging but so fun and fulfilling!

Sarah Breton (26) from France is currently based at: Aix-en-Provence, France. (Picture: private)


I just finished my PhD in passive neutron coincidence counting on radioactive waste drums. Although it is not applied to fusion, I am also very interested in it, and more generally, in wider topics of physics. Furthermore, I like to use my passion for drawing in order to illustrate physical phenomena and the life of researchers.

Benoît Simony (26) from France is currently based at: Aix en Provence,
France. (Picture: private)

The post The story of sabotage: the tungsten investigation appeared first on EUROfusion.

ITER’s Architect Engineer consortium receives “Industry and Technologies Consulting” award

F4E Events - ma, 06/11/2017 - 01:00
Egis, Assystem, Atkins, and Empresarios Agrupados are praised for their innovative work by the French Federation of Engineering Firms.

See the progress of ITER’s Neutral Beam Test Facility

F4E News - di, 31/10/2017 - 01:00
Take a peek inside the impressive infrastructure which will help scientists test powerful heating systems.

Magnet system | First superconducting component ready for tests

ITER - ma, 30/10/2017 - 19:12

From the outside, it's just another big, shiny stainless-steel pipe bent at a 90° angle. But take off the shipping caps at one end or the other, have a peek inside, and you will see a technological marvel.
A cryostat feedthrough is part of the feeder system that accommodates and relays all the essential "services" for the operation of a superconducting magnet.
Connected to a coil terminal box at one end and crossing into the cryostat at the other, it carries the superconducting busbars for the electrical current, the piping for the cryogenic fluids, and the cables for the diagnostics signals—all carefully insulated by an actively-cooled thermal shield and a vacuum duct.
Last week, the first of the 31 cryostat feedthroughs that must be delivered to the ITER construction site stood in the hall of the Magnet Infrastructure Facilities for ITER (MIFI), a workshop operated by a joint team from ITER and the French Alternative Energies and Atomic Energy Commission (CEA) to develop and qualify the ITER magnet elements and their assembly procedures.
Designed by the ITER feeder team, procured by the Chinese Domestic Agency, and manufactured at the Institute of Plasma Physics ASIPP in Hefei under the feeder team's supervision, the cryostat feedthrough is the first magnet component required on site because it needs to be brought into position before the completion of the cryostat base support ring.
At MIFI, the cryostat feedthrough will be subjected to high-voltage tests, leak tests and endoscopic inspections before being installed into the Tokamak assembly arena and later connected to poloidal field coil #4, one of the two largest of the machine's six poloidal field coils (24 metres in diameter).
To celebrate this highly symbolic event, representatives from CEA's Research Institute for Magnetic Fusion (IRFM), MIFI and the Chinese Domestic Agency joined ITER management and staff from the Magnets Division inside the MIFI hall, in the presence of the massive component.
"The arrival of this component is in itself a cause for celebration," said ITER Director-General Bernard Bigot. "It is the very first in a long line of magnet system elements for the most complex, most challenging electromagnetic device ever designed—the ITER Tokamak."
For Luo Dulong, head of ITER China, the moment—ten years, almost to the day, after the official establishment of the ITER Organization—will be "recognized as historical."
"MIFI is the most visible element of our cooperation with ITER in the field of superconducting magnets, and this component is the most spectacular among those that will be tested in this workshop," said Alain Bécoulet, the head of IRFM. "But it is only a beginning. As more magnet components are delivered to ITER in the coming weeks and months our collaboration with increase and expand." 
"We began working on feeders with ASIPP 12 years ago," reflected Neil Mitchell, head of the ITER Magnet Division. "It is hugely motivating for the different teams to see the arguments, discussions, tests and prototypes finally condense into the real component that is standing here today."
The long adventure is drawing to its successful conclusion—an indication that, in Luo Dulong's words, "ITER is in very good shape."
And so is fusion research as a whole: a few steps from MIFI, in a crowded and intensely silent control room, operators were monitoring plasmas shots in the Tore Supra tokamak, now refurbished into WEST and operating as a test platform for ITER.

Big Science Business Forum 2018 announces speakers and full programme, Copenhagen, 26-28 February 2018

F4E Events - vr, 27/10/2017 - 02:00
F4E is participating alongside the best European scientific organisations

Opening the Doors to Fusion

EFDA - wo, 25/10/2017 - 15:21

Related Information

EUROfusion welcomed hundreds of people to its stand at the annual science outreach event, the Garching Open Doors. The event showcased over 30 research institutes that call the Garching Forschungszentrum campus their home.

The EUROfusion stand

With Operation Tokamak, the video game that simulates the work of a tokamak operator, an energy-generating bicycle, and a smoke gun that shot out torus-shaped rings, the EUROfusion stand attracted the young and the old alike. Tony Donné, EUROfusion Programme Manager, who was at the stand answered questions about fusion and said that he was positively surprised at the interest the public showed. “These kinds of events are especially a great opportunity to meet the students who are really keen to learn more about the field,” he said. “I also got a chance to talk about how over the years spin-offs stemming from fusion research has helped other fields,” he added.

Queue to enter movie screening

But the highlight of the day was the German premier of the fusion documentary Let There Be Light. Over a hundred people queued up and reserved their spots for the screening later in the day. The documentary is the brain-child of award-winning director Mila Aung-Thwin. He spent four years filming people who have dedicated their lives to making fusion energy a reality on Earth. From those involved in ITER to those working on smaller undertakings in US and Canada, one common ambition ties the researchers together: the passion to realise fusion energy, no matter how long it takes.

(l-r) Tony Donné, Mark Henderson, Petra Nieckchen at the Q&A session following the movie

And one of these researchers, who also happens to be a protagonist in the film, ITER scientist Mark Henderson, flew in from France to attend the screening and participate in the following Q&A session. The Q&A session was an opportunity for the public to interact with fusion experts, Mark and Tony. “Many people do not have a clear understanding of exactly what fusion research is and why it is a challenge” said Mark. “The movie along with the Q&A gives a great platform to the fusion community to continue communicating about fusion and explaining to the larger public about why realising fusion energy is important to humankind,” he added.

The post Opening the Doors to Fusion appeared first on EUROfusion.

Project management | The elephant must be sliced

ITER - ma, 23/10/2017 - 19:09

Any way you cut it, ITER is fantastically complex. Whether you're counting components or the lines in the machine assembly schedule, or taking a closer look at the project's vast procurement sharing scheme ... complexity needs to be managed in ITER. Hans-Henrich Altfeld, head of the Project Control Office, tells us how it's done.

From a lay person's view, what makes the ITER Project stand out is the sheer scale of the undertaking in terms of size and budget, its level of scientific and technological innovation and, not least, its relevance to critical global issues.

A project manager looks at it differently. With costs of EUR 20 billion, millions of parts, supply chains spanning the entire globe and a multi-cultural workforce coming from 35 different countries, ITER is complexity to be managed. Altfeld has experience in the domain, having worked as a senior project manager for Airbus and in the automotive industry. His experience in mega projects is serving him now.

"Whereas at Airbus, 79,000 design drawings were needed for the development of the A380, at ITER we stand at 250,000 design drawings."

Why is it important to address complexity? "What we ultimately want to achieve is control over the project," Altfeld explains. "We do this by reducing its complexity. This will give us better control of the project, which is a precondition for success."

_To_125_Tx_Recognizing complexity is the first step to addressing and ultimately reducing it. But, how is this done with a project of this magnitude? "You have to slice the elephant," says Altfeld. Slicing the elephant? "You essentially cut the project into smaller units. This allows you to address the project in incremental steps that you manage individually."

At ITER, the "slicing of the elephant" follows the contour lines of other highly complex projects. "The ITER Project is not particularly unique in this sense," says Altfeld. It includes breaking down the entire project into systems, sub-systems and components; breaking down all required work into work packages; establishing and cascading requirements along with dedicated verification and validation plans; establishing a schedule governance which incorporates the activities of the Domestic Agencies, and developing a coordinate system for the ITER site.

"Slicing the elephant" requires tight management and strict control of the interfaces and interdependencies between the separate "slices."

"There is still room for improvement in this area," says Altfeld. "For ITER—as a first-of-a-kind experiment—it was impossible to identify all interfaces and interdependencies right from the beginning. It is learning by doing."

One example of the need for stricter interface control surfaced at a recent workshop. Considering the number of components the ITER machine will consist of and the extended time frame for construction, clear and understandable coding of components will ensure their correct placement in the machine. In previous years, not all components were coded early in the process, during the design phase. Now, these parts need to be coded retroactively—a situation that new procedures will correct in the future.

Another lesson learned from other mega projects is the importance of identifying and prioritizing risks and opportunities. These can be of a technical nature, or relating more to the project control issues of schedule or cost. New risk and opportunity management practices are helping the project to anticipate challenges in critical-path areas such as Tokamak Building construction and vacuum vessel manufacturing.

"Identifying the potential risks to delivery allows the project to develop and implement response actions," concludes Altfeld. "In the same way, it is of utmost importance to 'hunt' for opportunities—to proceed more quickly or optimize assembly sequences, for example—to make sure they can be cashed in on."

Europe delivers all of its cryogenic tanks to ITER

F4E News - ma, 23/10/2017 - 02:00
The massive fridge of the biggest fusion machine is shaping up.

Magnet feeders: first component completed

ITER - wo, 18/10/2017 - 11:51

In a major milestone for the ITER magnet procurement program China has successfully completed the first manufactured component of the feeder package: the cryostat feedthrough for poloidal field coil #4. The 10-metre, 6.6-tonne component is on its way now to the ITER Organization.
Measuring 30- to 50-metres in length, ITER magnet feeders will relay electrical power, cryogenic fluids and instrumentation cables from outside of the machine in to the superconducting magnets, crossing the warm/cold barrier of the machine.
These complex systems are equipped with independent cryostats and thermal shields and packed with a large number of advanced technology components such as the high-temperature superconductor current leads, cryogenic valves, superconducting busbars, and high-voltage instrumentation hardware.
Of the 31 feeders distributed around the vessel—and all supplied by China—six will service the poloidal field coils.
The component that is now en route to ITER is the cryostat feedthrough for poloidal field coil #4—the first magnet component required on site because it needs to be brought into position before the completion of the cryostat base support ring. Two other components—the in-cryostat feeder (nearest the vacuum vessel) and the coil termination box (outside the bioshield)—will complete the feeder that connects to the fourth poloidal field coil.
At the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) in July approximately forty scientists and engineers from the ITER Organization, the Chinese Domestic Agency, the European Domestic Agency, ASIPP and suppliers Keye Company and Henxing Company, took part in a milestone ceremony. ITER Director-General Bernard Bigot, who could not be present, sent his "warmest heartfelt congratulations" to the team members from different institutes who had all come together to realize this significant accomplishment according to schedule.
Arnaud Devred, who has led the Superconducting Systems & Auxiliaries Section at ITER for ten years—and who has made the "journey east" dozens of times—voiced his great sense of pride.
"The feeder system involves some of the most difficult and risky manufacturing and assembly processes of the ITER Tokamak, but thanks to the hard work and dedication of the teams at the ITER Organization, at the Chinese Domestic Agency, and at ASIPP and its subcontractors, we learned how to work together and to reconcile our cultural differences to meet the tough technical and quality control standards of the Procurement Arrangement. If we are at this successful point in the program today it is because, at our level and for our scope of the ITER Project, we have been able to develop the good collaborative spirit and mutual trust that has enabled us to overcome hurdle after hurdle and to achieve our common goals. I can only wish that the cryostat feedthrough for poloidal field coil #4 remains a testimony to common will power and shared resilience." 
The ceremony was especially poignant to Arnaud because he was just one month from leaving ITER to join the Large Hadron Collider Luminosity Upgrade at CERN that calls for the manufacture and installation of niobium-tin (Nb3Sn) dipole and quadrupole magnets—a type of superconductor that is massively used in the toroidal field and central solenoid coils of ITER. 
The complete magnet feeder system will weigh more than 1,600 tonnes and integrate more than 60,000 individual components.

Construction site | The lights of autumn

ITER - ma, 16/10/2017 - 20:32

Summer is over in Provence and the beautiful autumn light is back, revealing every detail of the landscape... and of the ongoing works on the ITER construction site.
Taken at the very end of the afternoon from the top of the highest worksite crane, this view takes in the "heart" of the ITER installation.
To the left, the Tokamak Complex with the spectacular structure of the bioshield at its centre, to the right four massive constructions: the twin Magnet Power Conversion buildings with three transformers already installed in their outdoor bays; the cryoplant, with its frame now covered in the trademark ITER stainless steel cladding; and the Poloidal Field Coils Winding Facility with its red trim... the first building to rise on the ITER platform.
View the gallery below for a full update of construction progress.

Crown mockup | Answering questions 3D models can't

ITER - ma, 09/10/2017 - 18:29

In some areas of the Tokamak Building the steel reinforcement is so dense and the arrangement of the bars so complex, that even the most detailed 3D models are not sufficient to demonstrate full constructability.
A 3D model certainly describes the position, dimension, relative angle and curvature of every steel bar needed in a construction with utmost precision. But there are important questions that a model cannot answer. What are the most efficient rebar installation sequences? Will there be enough moving room for the workers to insert the bars, manoeuver them into the right position, and tie the stirrups?
And the 3D model will provide no information on how the concrete will settle into the steel lattice.
This is why when things get particularly challenging, constructors choose to try their hand on a mockup. "A 1:1-size mockup provides the ultimate demonstration of constructability," explain Laurent Patisson and Armand Gjoklaj, from ITER's Civil Structural Architecture team. "It's all about learning and fine-tuning procedures."
Mockups for ITER construction are like everything at ITER—large and complex. Since work began on Tokamak Complex foundations seven years ago, mockups have been erected on three occasions: in 2013 for the building's supporting slab (B2); in 2015 for the bioshield; and now one for the "crown" that will support the combined mass (23,000 tonnes) of the machine's cryostat, vacuum vessel, magnet system and thermal shield. (Compared to the 2015 mockup, the present one includes more elements of the crown such as toroidal beams and circular wall.)
Construction of the latest mockup—which has a footprint of 50 m² and a height of 3 metres—began three months ago. Reproducing a 20-degree section of the crown, the mockup's dense lattice is created from 50-millimetre-thick steel bars, a breadth not encountered anywhere else in the Tokamak Complex.
The mockup will enable the Buildings Infrastructure and Power Supplies (BIPS) Project Team to demonstrate not only the feasibility of the rebar installation but also the penetration and placement of the concrete into the steel lattice.
The concrete's formulation for the crown ("C90") is also unique in the Tokamak Complex. It combines fluidity when poured and extreme "hardness" when settled.
Inside the mockup, the temperature during the hardening process will be regulated and homogenized by cooling water circulating inside of thin pipes¹ and monitored by sensors distributed throughout the structure.
In preparing for the actual construction of the crown, the BIPS Project Team feels confident but has decided to take no chances—the 1:1 mockup must deliver the final demonstration that, yes, it can be done.
(¹) Once the process is complete, the pipes will be filled with grouting.