62 ms·

Compact nuclear fusion reactor is 'very likely to work,' studies suggest

• bad_alloc 6y ago
  > If we can overcome the engineering challenges, this machine will perform as we predict If?
  • maxcan 6y ago
    Just like the alcubierre drive!
    • tesseract 6y ago
      The "Alcubierre drive" isn't an engineering design for a method of propulsion. It's just a nickname for a certain valid solution of the Einstein field equations. Like, in classical terms, you can get a repulsive force to come out of Newton's law of gravitation if you plug in a negative mass. But that doesn't mean you've designed a hoverboard.
      • mabbo 6y ago
        > But that doesn't mean you've designed a hoverboard. Must we spoil all my dreams?
  • princekolt 6y ago
    "Engineering challenges" means they already know the practical solutions, they just need to figure out how manufacture and assemble them.
• hikerclimb 6y ago
  Not really going to work... going to go boom!
• Someone 6y ago
  “Sparc takes advantage of a newer electromagnet technology that uses so-called high temperature superconductors that can produce a much higher magnetic field, Dr. Greenwald said. As a result, the plasma is much smaller.” So, is this ‘just’ a matter of ITER being obsoleted by improvements in magnet tech before it is completed, or is there more in this design than scaling down ITER?
  • vilhelm_s 6y ago
    I think at least the sales pitch is that the new magnets is all you need, and apart from that it uses the same well-understood technology that ITER is based around. https://www.psfc.mit.edu/files/psfc/imce/research/topics/sparc/MITSPARCbrochure.pdf https://www.psfc.mit.edu/files/psfc/imce/research/topics/spa...
  • magicalhippo 6y ago
    There's some discussion about this in this[1] presentation which also mentions the SPARC reactor. My main takeaway is basically yes, high-temp superconductors got "mainstream" very quickly. I'd recommend watching the whole thing, I found it quite interesting. [1]: https://youtu.be/L0KuAx1COEk?t=2929 https://youtu.be/L0KuAx1COEk?t=2929
    • willis936 6y ago
      It’s important to keep in mind that MIT is working hard to monetize HTS coil production. There are some unseen hush hush politics at play here.
  • tsomctl 6y ago
    ITER isn't meant to be a practical design, it's for research. So it's not obsolete just because it's using inefficient magnets.
    • avmich 6y ago
      It could be argued that ITER is actually quite important in learning how to deal with high technical complexity in general. Probably a good reason by itself to keep working on ITER, ISS is way simpler in comparison. https://en.wikipedia.org/wiki/ITER#Criticism https://en.wikipedia.org/wiki/ITER#Criticism "The project however was significantly delayed at the design stage as result of purposeful decision to decentralize its design and manufacturing among 35 participating states, which resulted in complexity that was unprecedented but consistent with the initial ITER goals of creating knowledge and expertise rather than merely producing energy."
• eigenhombre 6y ago
  Having read about tokamaks for thirty years, I'd be curious what specific breakthroughs and innovations have occurred since the 1980s, which lead to the optimism described in the article (which is otherwise frustratingly devoid of detail). It's great there are seven-peer reviewed articles about SPARC, but plasma was not my specialty in physics -- would any specialists care to comment on whether there is anything particularly exciting here?
  • jjoonathan 6y ago
    Superconductors recently got much better in a way that has cubic effect on reactor size.
    • cultus 6y ago
      I know essentially nothing about superconductors, but if they all have essentially zero resistance, what makes one better for this application? I thought the main advantage of high-temp superconductors was using liquid nitrogen instead of helium.
      • jjoonathan 6y ago
        They still saturate. High-temperature is nice, but a separate consideration.
      • willis936 6y ago
        HTS coils would still be run with liquid helium for higher critical current and higher magnetic field.
      • smaddox 6y ago
        High temperature superconductors provide more stable resistance-free conduction than traditional superconductors. If both are cooled to liquid helium temperatures, that increased stability translates to being able to sustain a higher magnetic field. Higher magnetic fields provide tighter plasma confinement and higher density, which allows for much smaller fusion reactors.
      • 6y ago
• isoprophlex 6y ago
  I never quite understood the math behind power densities in a fusion reactor. In the sun, isn't energy production occurring at something like 100-1000 W/m3? So, if you want to build a multiple MW fusion plant, shouldn't these plants be ridiculously huge compared to, say, a wind turbine rated at a couple of MW? Is the density of the plasma so much higher in a fusion reactor? Also, something else I never grokked, how do you get the power out? The plasma heats up, but how do you turn that into useful electrical energy? Nevertheless of course I hope it does work as advertised... someday. Edit: thanks everyone for the thoughtful, insightful replies!
  • arthurcolle 6y ago
    https://en.wikipedia.org/wiki/Thermoelectric_generator#:~:text=A%20thermoelectric%20generator%20(TEG)%2C,a%20form%20of%20thermoelectric%20effect https://en.wikipedia.org/wiki/Thermoelectric_generator#:~:te...).
  • 08-15 6y ago
    The sun "burns" ordinary hydrogen. The first step in this proton-proton-chain is the reaction of two protons to a deuteron, which requires conversion of one of them into a neutron. This is an interaction of the weak nuclear force, which has very small range, so it is slow. Reactions considered for terrestrial fusion don't require the weak force, and consequently won't run on pure hydrogen.
  • willis936 6y ago
    The density is actually lower than the sun in magnetic confinement fusion (MCF) devices because we can’t squeeze plasma together as hard as the sun’s mass can. Inertial confinement fusion (ICF) can squeeze harder than MCF devices, but has serious unaddressed engineering issues. The trick is in higher temperature plasma. The sun fuses protium (lone protons). We don’t have the confinement necessary on Earth to do this, so we fuse deuterium (1p+1n) and tritium (1p+2n). This reaction is more energetically favorable and is achievable on Earth. Coupled with giant microwave ovens and clever geometry and electromagnetic tricks, we can make plasmas much hotter (faster moving particles) than the sun can. Once a plasma is fusing, it emits a lot of heat (alpha heating and fast neutrons). A plasma that requires no external heating (no microwave ovens) is said to be “ignited”. We don’t necessarily need or want ignition to have a successful reactor, but it’s a cool thought. The major trouble with fusion reactors is keeping particles in the bottle long enough to fuse. Since they’re leaving anyway they have to go somewhere. You can tune vessel geometry and magnetic fields to have designated strike points where most of the plasma will exit confinement. These are called divertors. Run some coolant through your divertors and you have a heat source that can boil water and spin a turbine. Here my knowledge gets shaky because I know that the fastest particles coming out of a D+T reaction are neutrons (they weigh much less than an alpha particle). Since neutrons are electrically neutral I think they are much less likely to become thermalized (they are not likely to bump into another particle on their way out). I’m not sure how neutron thermalization happens in reactor simulations, but I’m under the impression that it does.
• deleted 6y ago
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• mdorazio 6y ago
  Here's the actual summary: "Although many significant challenges remain, the company said construction would be followed by testing and, if successful, building of a power plant that could use fusion energy to generate electricity, beginning in the next decade." In other words, "very likely" in this case means "if several roadblocks are overcome, it might be a net-positive power generator in a decade". Even so, this is still exciting given how anemic advancement in the fusion space has been for 50+ years.
  • Florin_Andrei 6y ago
    > this is still exciting given how anemic advancement in the fusion space has been for 50+ years At the top of my list for when I'll be king for a day is - massive, national-scale investments (think: reaching towards one percent of GDP) in fusion research. This is a major roadblock, but things look awesome on the other side. We just need to get our stuff together to hop over this fence somehow.
    • bilegeek 6y ago
      > massive, national-scale investments A reminder of what could have been: https://upload.wikimedia.org/wikipedia/commons/a/ab/U.S._historical_fusion_budget_vs._1976_ERDA_plan.png https://upload.wikimedia.org/wikipedia/commons/a/ab/U.S._his...
      • pfdietz 6y ago
        Yes, we could have wasted much more money back then (those crash budgets would not have worked, since they assumed tokamaks work better than it turned out they did.)
    • DataDaoDe 6y ago
      I couldn't agree more. Once you realize that energy is the fundamental unit which powers everything else in the economy, not only from every movement of ourselves to those of our machines as well, you realize the more we advance in our ability to produce more and more energy at cheaper and cheaper costs in increasingly reliable ways, the more we can accelerate, without exception, every other industry.
• Animats 6y ago
  How's the Lockheed effort coming along?[1] [1] https://lockheedmartin.com/en-us/products/compact-fusion.html https://lockheedmartin.com/en-us/products/compact-fusion.htm...
  • DennisP 6y ago
    Looks like they're still working, and on their fifth test reactor, the largest so far: https://www.thedrive.com/the-war-zone/29074/skunk-works-exotic-fusion-reactor-program-moves-forward-with-larger-more-powerful-design https://www.thedrive.com/the-war-zone/29074/skunk-works-exot...
    • skykooler 6y ago
      What happened to General Fusion's steam piston design? It seemed like such an elegant concept.
      • pfdietz 6y ago
        The supersonic implosion approach was shown to be unworkable for at least two reasons (the shock wave hitting the pusher/gas boundary broke into a forest of jets due to the Richtmeyer-Meshkov instability, and the currents in the surface of that pusher [ignoring the instability] would have been so high the push surface would have been vaporized, contaminating the plasma.) So they changed to a subsonic approach, and also moved to a spherical tokamak arrangement. This means the target now has a solid conductor running down the central axis, and this conductor would be exposed to utterly hellish levels of neutrons (orders of magnitude worse than conventional fusion reactors) as well as forces from 100T magnetic fields. I have no confidence this could be made to work, even for a single shot. Also, in subsonic implosion, there is pressure equilibrium in the pusher, so the outside of the chamber feels the same extreme pressure as the inside. 100T gives a pressure several times that of the bottom of the Marianas Trench.
• simonCGN 6y ago
  Still a nuclear reactor. Unsafe. Radioactive Waste. Not an Option Ahh, misread it. It’s about fusion, not fission. Ok then!
• Florin_Andrei 6y ago
  > Sparc would be far smaller than ITER — about the size of a tennis court, compared with a soccer field If we could make efficient fusion reactors the size of a truck, the solar system will become our backyard.
  • sempron64 6y ago
    What we really need are better ion propulsion systems. Even with a power source current ion propulsion systems are much slower than chemical rockets for short-term deep space missions like transit to Mars. https://en.wikipedia.org/wiki/Electrically_powered_spacecraft_propulsion https://en.wikipedia.org/wiki/Electrically_powered_spacecraf... Realistically, if we had good electric propulsion we could just slap a conventional fission reactor in there. We already launch plutonium on many deep-space missions for steady nuclear power. For now chemical propulsion is simply faster and more reliable, electric propulsion is still in the early stages, and there are many other problems to solve in human spaceflight.
  • pfdietz 6y ago
    DT fusion would be quite useless in space. The reactors are necessarily much larger than fission reactors, especially space reactors that can use highly enriched materials. And like fission it produces its energy as heat (from the neutrons.) Why use a large, complex heat source, when one can use a small, simple heat source?
• _Microft 6y ago
  The papers on the SPARC reactor seem to be here: https://www.cambridge.org/core/journals/journal-of-plasma-physics/collections/status-of-the-sparc-physics-basis https://www.cambridge.org/core/journals/journal-of-plasma-ph...
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• ivanb 6y ago
  Basic thermodynamics. Particle energy grows as T (because energy = 3/2 kT). Thermal radiation energy grows as T^4. At fusion temperature up to 80% of energy is in radiation. Energy density of radiation in this case is close to energy density of metals. It's impossible to contain such radiation.
  • maccam94 6y ago
    The SPARC design uses a combination of extremely high strength magnetic fields to contain charged particles inside the vacuum chamber and a molten-salt blanket (FLiBe) for neutron capture and cooling. They believe this will be a viable containment system.
    • ivanb 6y ago
      And what do they do with gamma radiation? As I said at thermonuclear temperatures it contains majority of the energy of the system.
      • maccam94 6y ago
        It is absorbed by the FLiBe salt blanket in the ARC design and converted to heat. The hot salt is circulated out and the heat is used for power generation before the salt is recirculated.
        • ivanb 6y ago
          Thanks for explaining. Good luck with removing all this gamma radiation from the system before it vaporizes the chamber but not fast enough as to cool the plasma and stop the reaction. I doubt that this sweet spot exists. Thermonuclear bombs exist only because plasma is surrounded by a thick layer of uranium which absorbs and re-emits gamma radiation thus not letting the plasma to cool. And this layer doesn't have to exist for too long. Less than a millisecond is fine to make a big enough bang.
• jhoechtl 6y ago
  Honest question: Has man-made nuclear fusion ever happened? Or is it theory, happening on the sun?
  • jhomedall 6y ago
    Hydrogen bombs use fusion.
  • correct_horse 6y ago
    Nuclear fusion happens in man-made thermonuclear bombs. I believe it also happens in research reactors that require more energy than they produce due to various inefficiencies.
  • cweagans 6y ago
    Fusion is relatively easy to achieve. Farnsworth and Hirsch did it back in the 60s and there's a community of people building DIY fusors at home. The hard part is getting the reaction to produce more energy than it requires to sustain. Given a breakthrough that solves that problem, fusion would be a really appealing energy source given the abundance of hydrogen.
  • mchusma 6y ago
    Yes man-made nuclear fusion is quite "easy". The hard part is getting more energy out than you put in. The sun does this all the time, basically by having so much mass that hydrogen gets sucked in by gravity to collide with other particles. Keeping hydrogen close enough to smash into each other is hard, the sun is just so big that it can do that. Hydrogen bombs do this by using other explosives to push hydrogen together. This isn't a good power source. We can't use gravity to cause hydrogen to collide here on earth (we have no artificial gravity). But we have magnets, so we try to bounce hydrogen particles around super fast in a small space with magnets instead of using gravity. Now getting more energy out is a bit like starting a fire. You need to apply heat for a while with a lighter before the fuel ignites, then the burning fuel keeps releasing energy. Same basic idea with fusion. You put in energy to start fusing hydrogen. Once the hydrogen is releasing power, it will cause other hydrogen particles to bounce around super fast and continue fusing, releasing more energy. The part that hasn't really been done yet is proving that the "fire" can stay lit, and that is what people are trying to do. It's hard for a bunch of reasons, but the theme is "making a tiny sun-like place on earth is challenging". When this article mentions "q" that is what it is referring to. q=2 means for every joule of energy put in you get 2 joules out. (disclaimer: this is a quick version that omits a lot)
• neonate 6y ago
  https://archive.is/7pkw0 https://archive.is/7pkw0
• nielsbot 6y ago
  My current favorite future fusion reactor project (I'm a layperson) is the Wendelstein 7-X: https://en.wikipedia.org/wiki/Wendelstein_7-X https://en.wikipedia.org/wiki/Wendelstein_7-X Seems like they're meeting all their planned milestones and it's going well! Excited for their next updates... More from their project page: https://www.ipp.mpg.de/w7x https://www.ipp.mpg.de/w7x "Wendelstein 7-X is the world’s largest fusion device of the stellarator type."
  • nielsbot 6y ago
    Looks like it's down for upgrades until the end of 2021.
  • zachrose 6y ago
    I’m also a layperson and also a fan of the 7-X, almost on purely aesthetic grounds. The plasma shape is a beautiful twisted loop, the magnets resemble a French crueler, and with the shielding and instrumentation it has all the charm of a steampunk time machine
    • 7373737373 6y ago
      As a layperson, this design seems far too complex to be useful for fast iterative research and ultimately, economic replication. It reminds me of the principle that one shouldn't start a space travel project that is estimated to take more than x years to complete, because by that time, technological progress will have surpassed its speed and capabilities, and would physically overtake it (the 'wait calculation').
      • neltnerb 6y ago
        Yeah, fusion is not fast to research though, ITER isn't even built yet. They're all extremely complicated, and while this one is harder to fabricate than a tokamak, fabricating arbitrary geometries is also something we've gotten a lot better at. If this is as complicated as it has to be in order to work as required... well, that's just physics right? The problem is unnecessary complexity, but whether that's the case here or not is still unclear.
• JustAPerson 6y ago
  https://www.youtube.com/watch?v=KkpqA8yG9T4 https://www.youtube.com/watch?v=KkpqA8yG9T4 Here's a video lecture from the MIT Professor (Dennis Whyte) who was leading the research group that provided some of the key designs for the SPARC reactor. As the NYT article explains, that research has been spun out into a startup that raised $200M. The key breakthrough is the advancement of REBCO tape superconductors which allow you to (1) generate record breaking magnetic field strengths (2) easily disassemble the super conducting loop for fast repairs / refuels / more modular design. It's a long talk, but it's extremely fascinating. Basically everything becomes much easier once you can increase the magnetic field strength. This talk is fairly accessible to even relative laypeople who have a vague understanding of E&M physics.
  • woeirua 6y ago
    That's a great talk, and really gives me a lot of hope for the SPARC concept that this article is about.
  • yboris 6y ago
    Phenomenal talk! I'm still watching - so captivating.
  • sien 6y ago
    Another excellent talk for those interested is MIT's Pathway to Fusion Energy (IAP 2017) - Zach Hartwig. https://www.youtube.com/watch?v=L0KuAx1COEk https://www.youtube.com/watch?v=L0KuAx1COEk He goes into detail about SPARC as well and why a higher magnetic field using HTS superconductors enables performance that can otherwise be obtained by greater size as ITER is trying.
  • maccam94 6y ago
    Timeline (in case you want to skip over some parts): 00:01:00 - introducing Dennis Whyte, MIT department head for nuclear science 00:04:24 - presentation starts 00:06:00 - identifies breakthrough with REBCO magnets 00:07:25 - explains deuterium-tritium fusion 00:12:30 - basic metrics for reactor performance 00:17:15 - energy output of other previous fusion experiments 00:19:00 - examines ITER and the problems of its approach 00:22:00 - problems solved by high energy magnetic fields 00:28:15 - full scale reactor concept, teardown of REBCO magnets 00:37:00 - design limits and margins 00:39:00 - fixes plasma instabilities found in weaker magnetic chambers 00:40:00 - maintainability, lifespan, component replacement 00:45:00 - solution to neutron damage and energy capture 00:50:30 - cost and profitability 00:54:00 - full graph of field strength vs reactor scale (and thus funding requirements) 01:01:50 - Q&A 01:30:00 - question about the biggest risks Also a more recent video, with more numbers and even more confidence than the first: https://www.youtube.com/watch?v=rY6U4wB-oYM https://www.youtube.com/watch?v=rY6U4wB-oYM
• splitrocket 6y ago
  Fusion, always, always 5 years away for the past 20 years.
  • 08-15 6y ago
    Yeah, but before that, it was 20 years away for about 50 years, so there is some progress after all! Seriously though, the article reads like "Remember SPARC? We're still trying to build it." I wish them luck, but if past experience with fusion can be extrapolated, they will run into some unexpected, crippling problems.
  • agar 6y ago
    Which is much better than the precedent since the 1950s, that fusion was always 20 years away.
  • maccam94 6y ago
    Up until 2005/2010 (the start of ITER), it was more like 30+ years away (ex: https://imgur.com/3vYLQmm https://imgur.com/3vYLQmm ). 5 years is a while but 2025 has been the target for CFS for several years now.
• woeirua 6y ago
  After watching the video posted in the top comment, I have to wonder why we would keep dumping money and time into ITER. I know, don't put all your eggs in one basket, but if the ITER design is so out-of-date, why wouldn't we just scrap it in favor of something that we could build 10 years faster and for much less money? It seems that if we can't make fusion work for SPARC it won't likely work in ITER either since they're both based on the same understanding of the physics. Am I wrong on that point? Is there some reason to think that ITER will succeed even if SPARC does not?
  • bpodgursky 6y ago
    Well, "we" is very precise -- it's an EU program, and this reactor is not. As far as "why", you can take your pick of: - ITER's design is older, and maybe could be considered "lower risk" (that it will work at all) - Sunk cost - Academic jobs program - Money has already been allocated to member states, and none are happy to give that up - Big changes take time I'm not optimistic on stuff like this, so IMO it's another JWST, but it's not totally crazy to keep working on a plan (for a while) when new avenues of research arise.
    • ClumsyPilot 6y ago
      Japan and US are members of the project. You should at least read basic info before speculating. https://www.iter.org/proj/Countries https://www.iter.org/proj/Countries
      • mbroncano 6y ago
        The EU is by far the biggest contributor though: > Europe is responsible for the largest portion of construction costs (45.6 percent); the remainder is shared equally by China, India, Japan, Korea, Russia and the US (9.1 percent each)
  • ClumsyPilot 6y ago
    Are you so sure ITER is obsolete? For instance, what prevents ITER to be upgraded with better magnets, like the ones used here, and to achieve higher power?
• pfdietz 6y ago
  Likely to work, but unlikely to lead to something economical. The volumetric power density (including the volume of everything inboard of the biological radiation shield) will still be grossly inferior to a fission reactor.
• yholio 6y ago
  About time to consider alternative paths to fusion. ITER and similar projects are abject failures from non-scientific perspectives, they fail to improve on the economic weaknesses of fusion (radiological waste, massive capital costs, scarcity of fuel, proliferation risk), and only deliver on issues that have become irelevant for modern fision, like the risk of a meltdown. There is zero economic potential for any ITER direct descendant.
  • dnadler 6y ago
    I wasn't aware of any radioactive waste from these fusion processes. I was also under the impression that fusion fuel is quite abundant (Deuterium and Lithium as an example discussed in one of the videos linked in the comments).
    • yholio 6y ago
      There are no fission waste products but the reactor deals with massive neutron fluxes that activate all internal components, coolants and the internal fuel fluxes that need to be processed in order to keep the reaction going. The Deutherium-Lithium route is not direct, you need to breed Tritium, a hazardous radioactive gas. There is poor neutron economy and you need neutron multiplicators that also become activated. While I agree the quantity of waste is low, that doesn't really matter for the general public. We had for decades the technology to put fission waste in deep geological storage, what held it up were political concerns - the same for fast breeders that could burn the waste. So I cannot for the life of me understand how NIMBY-ism, the major cost driver of fission plants (via political challenges, court actions, schedule slips etc.), is allayed, when the plant will regularly ship out tons of hazardous materials through the communities they serve. As for the fuel cost issue, you cannot use natural Lithium due to low cross section, but blankets made up of tons of enriched Lithium that has a large Li6 content, that are continually circulated and need to be topped off as H3 is bred. No estimate of cost for this feed-stock exists, but it is likely more expensive than natural uranium that can be burnt in a heavy water reactor, for example. (that reactor design has it's own issues with heavy water inventory costs, but this material is most probably easier to produce than enriched Li6, and is not consumed as a fuel) When you draw the line, the best prospects of ITER derived fusion plants (not existing experiments, mind you, but the theoretical future, practical designs) is at best comparable to existing fusion plants. Why should we waste money on them, if they cannot improve on the current state of the art?
• Krasnol 6y ago
  Related: Cities Snub Plan to Save Nuclear Power With Mini Reactors: https://www.bloomberg.com/news/articles/2020-09-28/cities-snub-plan-to-save-nuclear-power-with-mini-reactors https://www.bloomberg.com/news/articles/2020-09-28/cities-sn... Kaysville withdraws from nuclear power project: https://outline.com/LAfTYG https://outline.com/LAfTYG Small Modular Reactor Decision Made With Inadequate Information: https://losalamosreporter.com/2020/09/14/small-modular-reactor-decision-made-with-inadequate-information/ https://losalamosreporter.com/2020/09/14/small-modular-react...
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• Tossrock 6y ago
  I wish these people the best, and I really hope they get a working fusion plant soon. That said, I can't resist sharing Admiral Rickover on academic reactors vs practical reactors: Important decisions about the future development of atomic power must frequently be made by people who do not necessarily have an intimate knowledge of the technical aspects of reactors. These people are, nonetheless, interested in what a reactor plant will do, how much it will cost, how long it will take to build and how long and how well it will operate. When they attempt to learn these things, they become aware of confusion existing in the reactor business. There appears to be unresolved conflict on almost every issue that arises. I believe that this confusion stems from a failure to distinguish between the academic and the practical. These apparent conflicts can usually be explained only when the various aspects of the issue are resolved into their academic and practical components. To aid in this resolution, it is possible to define in a general way those characteristics which distinguish the one from the other. An academic reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose ("omnibus reactor"). (7) Very little development is required. It will use mostly “off-the-shelf” components. (8) The reactor is in the study phase. It is not being built now. On the other hand, a practical reactor plant can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It is requiring an immense amount of development on apparently trivial items. Corrosion, in particular, is a problem. (4) It is very expensive. (5) It takes a long time to build because of the engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated. The tools of the academic-reactor designer are a piece of paper and a pencil with an eraser. If a mistake is made, it can always be erased and changed. If the practical-reactor designer errs, he wears the mistake around his neck; it cannot be erased. Everyone can see it.
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  • samatman 6y ago
    It's a good contribution to the conversation, keeping in mind that Adm. Rickover wrote these words in 1953. Anyone could have said similar things about computers in 1953, and been just as correct. Are nuclear reactors computers? Of course not, and neither have practical reactors kept pace in development with practical computers. But neither is it inevitable that steady progress cannot grind down the latter set of characteristics into the former. Indeed, that's what I would bet on, and I think the Admiral would be disappointed in the progress we have(n't) made.
• natch 6y ago
  What are the decommissioning costs? Who will pay for the cost overruns? Just one of the big problems with nuclear is that it is very centralized and takes individual control away from the consumers, who foot the bill through increased taxes and fees, and who could otherwise be using their money to finance options that give them individual control over their energy costs.
  • maccam94 6y ago
    This reactor prototype has gotten private investment, because it is both comparatively affordable (hundreds of millions instead of tens of billions of dollars) and it will likely be profitable to license the technology to commercial plant operators. It is unlikely that commercial reactors would require public funding. Decommissioning costs should be negligible because the reactors won't generate radioactive fission byproducts. The reactor chamber is designed for a 10 year lifespan and easy replacement. The old chamber is slightly radioactive (due to neutron bombardment) for a few decades, which is much less of a problem than the highly radioactive waste from fission plants that has to be stored for thousands of years.
    • natch 6y ago
      Yeah no thanks... at those prices this is still centralized and the costs of corruption and “few decades” decommissioning after a mere 10 years of usefulness will still be passed along through government subsidies and taxation. I’d rather just install solar and have control of these costs myself.
    • natch 6y ago
      So you say the chamber has a 10 year lifespan but has been bombarded with radiation for a few decades. Do you see any contradiction there? How does that work.
• non-entity 6y ago
  Urjfjvjvjdj
• Ice_cream_suit 6y ago
  I just hope that it does not turn out be be Nikola 2.0
• hexbinencoded 6y ago
  Fusion has always been "just around the corner." These stories aren't helpful until there is demonstrable evidence it delivers on the so-far vaporware promises of many other projects before it.
• alex_young 6y ago
  Let’s say this works. What do you do with all the neutrinos? How do you deal with all of the radioactive waste from the containment equipment?
  • Deestan 6y ago
    Neutrinos: https://what-if.xkcd.com/73/ https://what-if.xkcd.com/73/ Waste: https://www.iaea.org/topics/energy/fusion/faqs https://www.iaea.org/topics/energy/fusion/faqs
    • alex_young 6y ago
      From your IAEA link: “ The activation of the reactor’s structural material by intense neutron fluxes is another issue. This strongly depends on what solution for blanket and other structures has been adopted, and its reduction is an important challenge for future fusion experiments.”
• pontifier 6y ago
  Im just going to keep plugging my reactor effort every time fusion is mentioned here... http://www.DDPROfusion.com http://www.DDPROfusion.com
  • sebmellen 6y ago
    Good luck with the fund-raising!
• physicsguy 6y ago
  So, I'm a physicist, and I went to a number of talks from people involved with the JET fusion reactor over the years, though fusion is not my area. And my understanding is not that it's difficult to make plasma, or even build a reactor in particular that is the main problem (though instabilities can be problematic), but it's that the internal structure degrades very rapidly and becomes highly radioactive, because you get helium bubbles forming inside the steel which causes fractures and the heavy metals that are often put into steel to increase strength are highly fissionable. So you need to use special types of steel to actually construct the reactor, and these need to have a lifetime that's ~5 years+ and it needs to not have very very radioactive steel at the end of it's usable life. And this is basically an unsolved materials science problem at the moment. So while you might even be able to build a fusion reactor, it's not going to last long enough to make it commercially viable using current technology.
  • varjag 6y ago
    That's a luxury problem at the moment. A fusion reactor that can sustain positive output operation for 5 years is still a dream.
    • OJFord 6y ago
      Sort of, but only if you exclude the amortised cost of fabrication from your calculation - it's part of the same goal, unlike say 'they're hard to make, we can't make them fast enough to put a dent in energy production'.
    • jnxx 6y ago
      It is a total show-stopper because you don't have the amount of Tritium to power such a reactor.
      • DennisP 6y ago
        We have plenty of lithium. All D-T fusion designs breed tritium from lithium, using the high-energy neutrons from the reaction.
• HeavyStorm 6y ago
  So, my nuclear-powered exoesqueleton dream will come true!
• o-o- 6y ago
  A couple of reflections. The first one being that fusion might very well be the remedy to get rid of carbon emissions once and for all, however it won't affect global warming. In fact, it might make it even worse. The simple line of reasoning being that if energy becomes 100 times cheaper, humanity will fast find ways to consume 100 times the amount of energy. A high amount of that energy will end up as heat. The second reason... and you'll find it apparent I'm not a physicist, but reading about fusion research always has me worried. We're basically talking about starting a "controlled" chain reaction at millions of degrees, "like the one on the sun". The sun isn't a nice place, and the sun's fusion happens to be controlled just because it's surrounded by lightyears of vacuum. -Yeah but we'll have magnetic fields and super coils and stuff. It's totally safe. -Totally safe? -Yes, our calculations say its totally safe. -Your calculations based on current theory? Guess what, theory is a moving target. Just a few years ago you didn't even know if the Higgs particle exists?
  • blamestross 6y ago
    Just to give a little insight, the "containment" isn't about safety, it is about squeezing everything together. It goes away, so does the reaction. It fizzles, it doesn't blow up. The fusion in the sun is essentially gravity+mass applying so much pressure that stuff fuses. Fusion hypothetically is by far the safest means of getting power we will ever work out. Global warming isn't about heat generation. The sun (the free fusions reactor in the sky) sends more heat our way then we could ever hope to produce. It is heat dissipation that is the problem. Greenhouse gasses prevent the sun's heat from dissipating. This is the problem, we will only make it better by stopping greenhouse gas emissions.
• cromwellian 6y ago
  a lot of people commenting who actually didn’t watch the presentations and making sweeping bad takes nuclear power in general which are really just criticisms of PWRs (pressurized water reactors)
• ratdragon 6y ago
  I'm rooting for LPP Fusion https://lppfusion.com/ https://lppfusion.com/ it is a "garage" startup but their approach of using plama instability instead of trying to stabilize it (and the fact they're very close already to net gain https://lppfusion.com/investing-in-lppfusion/our-plan-to-net-energy/ https://lppfusion.com/investing-in-lppfusion/our-plan-to-net...) sure sounds great. Garage sized 5MW aneutronic pb11 fusion reactor with direct-to-electricity conversion sure sounds like something we all can use :)