Posts Tagged ‘JET’
nuclear fusion developments 1
This post is also published on my Solutions OK blog.
As a person much addicted to reading, I’ve been impressed by a writer who’s been eloquently cataloguing global problems and solutions in the Anthropocene. Gaia Vince (I presume her parents were Lovelock fans) has written 3 books, Adventures in the Anthropocene, Transcendence and Nomad century, the first two of which I now possess, the first of which I’ve read, the second of which I’m well into, and the third of which I intend to buy. So, time to return to my own self-education notes on solutions…
Vince appears to be my opposite – adventurous, extrovert, successful, in demand, and doubtless eloquent in person as well as in print. Bitch! Sorry, lost it there for a mo. The heroes and heroines of her first book, the product of travels though Asia, South America, Africa and the WEIRD world, and the solutions they’ve created and pursued, will, I think, provide me with pabulum for many blog pieces as I sit, impoverished (but not by global standards), uneducated (in a formal sense) and unlamented in rented digs in attractive and out-of- the-way, Adelaide, Australia, once touted as the ‘Athens of the South’ (at least by Adelaideans).
What I’ve found in my research on solutions – and Vince’s explorations have generally borne this out – is that solutions to global or local problems have created more problems which have led to more solutions in a perhaps virtuous circle that’s a testament to human ingenuity. And the fact that we’re now 8 billion, with a rising population but a gradually slowing rate of rising (in spite of Elon Musk), shows that we’re successful and trying to deal with our success…
So what are our Anthropocene problems? Global warming, of course. Destruction of other-species habitats on land and sea. Damming of rivers – advantaging some groups and even nations over others. Rapid industrial change (I’ve worked – mostly briefly! – in a half-dozen factories, all of which no longer exist). Population growth – in the 20th century from less than 2 billion to over 6 billion, and over 8 billion by May 2023. Toxic waste, plastic, throwaway societies, social media addiction and polarisation, the ever-looming threat of nuclear warfare… and that’s enough for now.
But on a more personal level, there’s the problem of how to navigate the WEIRD world, a world that bases itself on individualism, that’s to say individual freedom, when you don’t believe in free will (or rather, when you’re certain that free will is bullshit). And yet… a lot of smart, productive people don’t believe in free will (Sam Harris, Robert Sapolsky, Sabine Hossenfelder), and it doesn’t seem to affect their activities and explorations one bit – and to be honest it doesn’t affect my work, such as it is, either, though it does provide me with a handy excuse for my failings. My introversion has been ingrained from earliest childhood (see the Dunedin study on personality types and their stability throughout life), my lack of academic success has been largely due to my toxic family background, bullying at school, and lack of mentoring during the crucial learning period (from 5 to 65?), and my lifelong poverty (within the context of a highly affluent society) is not entirely due to laziness, but more to do with extreme anti-authoritarianism (hatred of ‘working for the man’) and a host of other issues for which I blame my parents, my social milieu, my genes and many other determining factors which I’m determined not to think about right now.
Anyway, with no free will we humans have managed transformational things vis-à-vis the biosphere, and there will be more to come. In her epilogue to Adventures in the Anthropocene, Vince hazards some predictions, using the narrative of someone looking back on the century from the year 2100, and considering the book is already about ten years old, I might use the next few posts to look at how they’re faring.
So – nuclear fusion. Here’s Vince’s take:
In 2050, the first full-scale nuclear fusion power plant opened in Germany (after successful experiments at ITER, in France, in the 2030s), and by 2065 there were thirty around the world, supplying one-third of global electricity. Now, fusion provides more than half of the world’s power, with solar making up around 40% and hydro, wind and waste (biomass) making up the rest.
So I’m starting with a very recent video by the brilliant Matt Ferrell, as a refresher for myself. Nuclear fusion, the source of the sun and stars’ energy, involves two small atoms colliding to form a larger atom (e.g. hydrogen forming helium), with some mass being converted to energy in the process. And I mean a really large amount of energy. To quote Ferrell:
Once the fusion reaction is established in a reactor like a tokamak, a fuel is required to sustain it. There’s a few different fuels that are options: deuterium, tritium or helium-3. The first two are heavy isotopes of hydrogen… most fusion research is eyeing deuterium plus tritium because of the larger potential energy output.
The power released from fusion is much greater, potentially, than that derived from fission. And deuterium plus tritium produces neutrons, which creates a process called neutron activation, which induces relatively short-lived but problematic radioactivity. And there are a host of other challenges, but it’s clear that incremental progress is happening. People may have heard of JET (the Joint European Torus) and the unfinished ITER (the International Thermonuclear Experimental Reactor), and of recent promising developments – for example, this:
A breakthrough in December 2022 resulted in an NIF [Nuclear Ignition Facility] experiment demonstrating the fundamental scientific basis for inertial confinement fusion energy for the first time. The experiment created fusion ignition when using 192 laser beams to deliver more than 2 MJ of ultraviolet energy to a deuterium-tritium fuel pellet.
Ferrell visited the Culham Science Centre, near Oxford in the UK, where he was shown through the RACE (Remote Applications in Challenging Environments) facility, a perfect acronym for the time. They’ve created a system there called MASCOT, which appears to be a cyborg sort of thing, but mostly mechanical – with a human operator. The aim is to incrementally develop complete automation for maintenance and upgrading of these highly sensitive and potentially dangerous components. Since everything is still at the experimental stage, with a lot of chopping and changing, flexible human minds are still required. Full automation is clearly the goal, once a reactor is up and running, which is still far from the case. Currently, it requires about a thousand hours of training to work with the machinery and the haptics in this pre-full automation stage, bearing in mind that the types of robotic and cable systems are still being worked out. Radiation tolerance is an important factor in terms of future developments. Culham uses a ‘life-size’ replica of a tokamak for training purposes.
RACE, as the acronym suggests, is not just a facility for nuclear research but for dealing with hazardous environments and materials in general. Moving on from JET, Ferrell visited the new MAST-U (Mega Amp Spherical Tokamak – Upgraded!). As Ferrell points out, the long lag time between promise and results in nuclear fusion has often been the butt of jokes, but this ignores many big recent developments, described well by Dr Melanie Windridge in a Royal Institute lecture, of which more later.
In the video we see a real tokamak from the sixties, probably the first ever, sitting on a table, to indicate the progress made. MAST-U’s major focus at present is plasma exhaust and its management, essential for commercial fusion power. Its new plasma exhaust system is called Super-X, a load-reducing divertor technology vis-a-vis power and heat, so increasing component lifespans. One of the scientists described the divertor as like the handle in a hot cup of coffee:
So our plasma is the coffee that we want to drink. It’s what we want, right? We want this coffee as hot as possible, but we won’t be able to handle it with our hands, we need a handle, and the diverter has the same function, it tries to separate this hot, energetic plasma from the surface of the device. So we divert the plasma into a different region, a component specifically designed to accommodate this large excess energy.
The divertor is the key factor in the upgrade and is drawing worldwide attention, as it has supposedly improved plasma heat diversion by a factor of ten, as I understand it. And MAST-U’s spherical design is potentially more efficient and cheaper than anything that has gone before. All a step or two towards more viable power plants. And, returning to JET, you can see in the video how massive the system is compared to the table-top version of the sixties. JET came into being in the 80s, and has had to deal with and adapt to many new developments, such as the H-mode or high-confinement mode, a new way of confining and stabilising plasma at higher temperatures, which has gradually become standard, requiring engineering solutions to the torus design. It’s expected that AI will play an increasing role in new incremental modifications. Simulations to test modifications can be done much more quickly, in quicker iterations, via these advances. AI, computer modelling and advances in materials science and superconductors are all quickening the process. JET will be decommissioned in about 12 months, but much is expected to be gleaned from this too, as they look at how neutrons have affected material components.
Another issue for the future is tritium, supplies of which are currently insufficient for commercial fusion production. According to ITER, current supply is estimated at 20 kilos, but tritium can be produced, or ‘bred’ within the tokamak through the interaction of escaping neutrons with lithium. Creating a successful tritium breeding system is essential due to the lack of external sources.
So that’s enough for now, I’ve gone on too long. To be continued.
References
Gaia Vince, Adventures in the Anthropocene, 2014.
https://www.iter.org/mach/TritiumBreeding
Exploring the future of nuclear fusion
Canto: So, with Christmas cookery and indulgence behind us, it’s time to focus on another topic we know little about, nuclear fusion – or I should say human-engineered nuclear fusion. Ignition has recently been achieved for the first time, so where do we go from here?
Jacinta: Well I listened to Dr Becky the astrophysicist on this and other topics, and she puts the ignition thing into perspective. So it occurred back on December 5 at the National Ignition Facility in California. As Dr Becky explains it, it involves ‘taking 4 atoms of hydrogen and forcing them together to make helium’, which is slightly lighter than the four hydrogens, and this mass difference can, and in this case has, produced energy according to special relativity. Of course fusion occurs in stars (not just involving hydrogen into helium) and it can potentially produce huge volumes of clean energy. But there’s a big but, and that’s about the high temperatures and densities needed for ignition. Those conditions are needed to overcome the forces that keep atoms apart.
Canto: Yes they used high-powered lasers, which together focus on heavy hydrogen isotopes – deuterium and tritium – to produce helium. And this has been achieved before a number of times, but ignition specifically occurs when the energy output is greater than the input, potentially creating a self-sustaining cycle of fusion reactions. And the difficulties in getting to that output – that is, in creating the most effective input – have been astronomical, apparently. They’ve involved configuring the set of nearly 200 lasers in the right way, using ultra-complex computational analysis, recently guided by machine learning. And this has finally led to the recent breakthrough, in which an energy input of 2.05 megajoules produced an output of 3.15 megajoules…
Jacinta: 1.1 megajoules means ignition, though it’s nothing earth-shattering energy-wise. It’s apparently equivalent to about 0.3 kilowatt-hours (kWh) – enough energy for about two hours of TV watching according to Dr Becky. And also this was about the energy delivered to the particles to create the reaction, it didn’t include the amount of energy required to power the lasers themselves – approximately 300 megajoules. So, good proof-of-concept stuff, but scaling up will be a long and winding road, wethinks.
Canto: Another favourite broadcaster of ours, theoretical physicist Sabine Hossenfelder, also covers this story, and provides much the same figures (400 megajoules for the lasers). She also points out that, though it’s a breakthrough, it’s hardly surprising given how close experimenters have been getting to ignition in recent attempts. And she is probably even more emphatic about the long road ahead – we need to ramp up the output more than a hundred-fold to achieve anything like nuclear fusion energy at economically viable levels.
Jacinta: I’m interested in the further detail Dr Hossenfelder supplies. For example the NIF lasers were fired at a tiny golden cylinder of isotopes. There must be a good reason for the use of gold here. She also describes the isotopes as ‘a tiny coated pellet’. What’s the coating and why? She further explains ‘the lasers heat the pellet until it becomes a plasma, which in turn produces x-rays that attempt to escape in all directions’. This method of arriving at fusion is called ‘inertial confinement’. Another competing method is magnetic confinement, which uses tokamaks and stellarators. A tokamak – the word comes from a Russian acronym meaning ‘toroidal chamber with magnetic coils’ – uses magnetism to confine plasma in a torus – a doughnut shape. A stellarator…
Canto: Here’s the difference apparently:
In the tokamak, the rotational transform of a helical magnetic field is formed by a toroidal field generated by external coils together with a poloidal field generated by the plasma current. In the stellarator, the twisting field is produced entirely by external non-axisymmetric coils.
Jacinta: Ah, right, we’ll get back to that shortly. The Joint European Torus (JET) holds the record for toroidal systems at 0.7, which presumably means they’re a little over two thirds of the way to ignition.
Canto: A poloidal field (such as the geomagnetic field at the Earth’s surface) is a magnetic field with radial and tangential components. Radial fields are generated from a central point and weaken as they move outward.
Jacinta: PBS also reports this, citing precisely 192 lasers, and a 1mm pellet of deuterium and tritium fuel inside a gold cannister:
When the lasers hit the canister, they produce X-rays that heat and compress the fuel pellet to about 20 times the density of lead and to more than 5 million degrees Fahrenheit (3 million Celsius) – about 100 times hotter than the surface of the Sun. If you can maintain these conditions for a long enough time, the fuel will fuse and release energy.
Canto: So the question is, does nuclear fusion have a realistic future as a fuel?
Jacinta: Well, did the internet have a realistic future 50 years ago? We’ve had a breakthrough recently, and the only way is up.
Canto: Yeah the future looks interesting after I’m dead. Still, it’s worth following the progress. Back in February The Guardian reported that JET had smashed its own world record, producing ’59 megajoules of energy over five seconds (11 megawatts of power)’. Whatever that means, it wasn’t ignition – it might’ve been the .7 you mentioned earlier. Creating a mini-star for five seconds was what one experimenter called it, which I think was in some ways better than the current effort, in that it created more energy in absolutes terms, but less energy than the input.
Jacinta: Perhaps, but what they call ‘gain’ is an important measure. This recent experiment created a gain of about 1.5 – remember just over 3 megajoules of energy was put out from just over 2 megajoules of input. It’s a start but a much bigger gain is required, and the cost and efficiency of the lasers – or alternative technologies – needs to be much reduced.
Canto: Apparently deuterium and tritium are both needed for effective fusion, but tritium is quite rare, unlike deuterium, which abounds in ocean waters. Tritium is also a byproduct of the fusion process, so the hope is that it can be harvested along the way.
Jacinta: Of course the costs are enormous, but the benefits could easily outweigh them – if only we could come together, like bonobos, and combine our wits and resources. Here’s an interesting quote from the International Atomic Energy Agency:
In theory, with just a few grams of these reactants [deuterium and tritium], it is possible to produce a terajoule of energy, which is approximately the energy one person in a developed country needs over sixty years.
Canto: Really? Who will be that lucky person? But you’re right – collaboration on a grand scale is what this kind of project requires, and that requires a thoroughly human bonoboism married to a fully bonoboesque humanism….
References
https://www.theguardian.com/commentisfree/2022/dec/13/carbon-free-energy-fusion-reaction-scientists
https://www.iaea.org/bulletin/what-is-fusion-and-why-is-it-so-difficult-to-achieve