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Nuclear fusion has encountered a shortage of tritium
- api 4y agoCan't an operational fusion reactor breed tritium? If so we just need enough tritium to start one.
- ceejayoz 4y agoThe article covers that. > Tritium breeding was originally going to be tested as part of ITER, but as costs ballooned from an initial $6 billion to more than $25 billion it was quietly dropped. Willms’ job at ITER is to manage smaller-scale tests. Instead of a full blanket of lithium surrounding the fusion reaction, ITER will use suitcase-sized samples of differently presented lithium inserted into “ports” around the tokamak: ceramic pebble beds, liquid lithium, lead lithium. > Even Willms admits that this technology is a long way from being ready to use, however, and a full-scale test of tritium breeding will have to wait until the next generation of reactors, which some argue might be too late. “After 2035 we have to construct a new machine that will take another 20 or 30 years for testing a crucial task like how to produce the tritium, so how are we going to block and stop global warming with fusion reactors if we will not be ready until the end of this century?” says Mazzucato.
- api 4y agoOops missed that. ITER is not necessarily the best approach to fusion, although it's the best funded. In any case if we can't breed tritium than we either need to shoot for higher energy D-D fusion or some other reaction or fusion will never be cost-competitive.
- GuB-42 4y agoIs there any other approach to fusion than ITER? I mean fusion capable of practical power generation. D-T fusion is the easiest, and yet super hard. Tokamaks are the only design that we know how to build in order to meet the goal, with maybe stellerators in second position. Inertial fusion work for scientific and military experiments, but are far from being a usable power source. Things like fusors and its derivative are great hobby projects with a few limited practical applications, but we are not even sure if it is physically possible to produce more energy than we put in. As for LENR (aka. cold fusion) we are essentially at the "thought experiment" stage, when it is not a scam. One other idea that may work with current tech is to dig a large cave, line it with really thick material and detonate hydrogen bombs inside it, extracting energy from the heat of the explosion. I don't think I need to tell you that even if we can do that (unsure), we certainly shouldn't (absolutely sure). Or, take, advantage of that really big fusion reactor we already have and makes us go around in circles.
- DennisP 4y agoMost conservatively, there are tokamaks that use more modern superconductors, able to support much stronger magnetic fields. Tokamak output scales with the fourth power of the magnetic field, so that allows the same output as ITER from a much smaller, cheaper reactor. The MIT spinoff CFS is doing this, along with Tokamak Energy in the UK. CFS is shooting for a net power attempt in 2025. There are also various alternative designs, like Zap Energy's z-pinch, General Fusion's magnetized target fusion, and Helion's field-reversed configuration. Helion is attempting hybrid D-D/D-He3 fusion, the other two are D-T.
- pfdietz 4y agoAll the DT approaches suffer from poor volumetric power density, for fundamental reasons independent of the details of magnetic fields or confinement schemes. For that reason I feel Helion's approach is the least dubious.
- cpuguy83 4y ago$25 billion... thinking about how much money we've dedicated for active warfare in the last 2 months alone... clearly we have our priorities.
- gwright 4y agoI struggle to understand this type of comment. You can't respond to the bad guys with a plea for them to stop what they are doing because you would rather spend the money on something else. That isn't to say that battles should not be picked carefully, just that sometimes you don't have a choice and have to deal with a situation and spend lots of $$$ and sometimes blood in order to avoid a worse situation. Even in the context of "last 2 months alone" it isn't clear what specific action is being referenced so the comment is just too abstract, IMHO. In some cases it makes sense to engage, in others it doesn't. There is no single correct answer unless you want to enter into a discussion of pacifism.
- prox 4y agoThat is not what that comment says. It clearly means money can be spent when we go to war, or when we need pandemic money, but a measly 25billion in comparison suddenly is “a lot”. If we want fusion, we have to invest.
- jessaustin 4y agoWe do have a choice about Ukraine, just as we had a choice about Syria, Libya, Iraq, Yemen, Afghanistan, Vietnam, Honduras, Guatemala, El Salvador, etc. We are making the wrong choice now, just as we made the wrong choices before. Although we kill lots of people, many of them innocent rather than "bad", we never actually "avoid" worse situations. In cases like Libya our intervention has worsened human life by every measure. In other cases we might have delayed inevitable events somewhat (e.g. Vietnam couldn't go to war with China until it finished beating us). The "specific action" in every case is spending public funds, which is the purpose of the USA military, intelligence services, diplomatic corps, and news media, and has been since the Korean War. Insofar as they affect security at all, our military efforts usually reduce it.
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- BurningFrog 4y agoI'm very unimpressed by the "we must only consider short term solutions to global warming" idea. We don't know the future, and we keep being surprised by it!
- adgjlsfhk1 4y agoif we want to significantly curb global warming, long term solutions aren't where we need to focus effort
- DennisP 4y agoThen it's a good thing we're not focusing effort on long-term solutions. We're spending a lot more money on rolling out renewables than we are on fusion research. That doesn't mean we should cut out long-term solutions entirely. If we want to fund more renewables than we are now, then the place to cut back is the many fossil fuel projects that we're still investing in. Until we've done that, I think any positive effort deserves applause instead of complaints about focus.
- seniorsassycat 4y ago> There are other ways of creating tritium but these techniques are too expensive to be used for the quantities required, and they will likely remain the reserve of nuclear weapons programs Too expensive for clean power, just right to threaten the world
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- ncmncm 4y agoTakes less for the latter.
- Victerius 4y ago"Precious tritium is what makes this project go. There's only 25 pounds of it on the whole planet."
- rmdashrfstar 4y agoWhat about in near earth asteroids?
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- dodobirdlord 4y agoTritium has a half-life of about 12 years, meaning that it essentially doesn’t exist naturally. It’s all man made.
- Goronmon 4y agoJust to provide the other half of the concern around how little there is. ...it’s estimated that working fusion reactors will need up to 200 kg of it a year
- AustinDev 4y agoThe working fusion reactors will produce enough to not need additional tritium, it is a self-sustaining reaction after all.
- ceejayoz 4y ago> There's only 25 pounds of it on the whole planet. "Because we haven't needed more until now, and it's mostly man-made." There wasn't any plutonium on Earth, either, until we decided we needed some.
- adrian_b 4y agoActually, when the Earth was formed, it contained a non-negligible quantity of plutonium (supernovae produce all the elements until Z=100, much over the Z=94 of plutonium, but the heavier elements had already decayed before the interstellar dust reached the nascent Solar System). Because the longest-lived isotope of plutonium has a half-life close to 100 million years, so some 45 halvings have happened since the Earth formation, almost all primordial plutonium has decayed by now. A few atoms of the primordial plutonium are still around us, though they are much too few to be easily detectable (there have been claims that some very sensitive experiments have detected them).
- photochemsyn 4y agoTell that to the Sun. We already have a fusion reactor sufficient to meet all of humanity's energy needs, it's a gravitationally contained fusion reactor with a projected lifetime of at least one billion years, so why not just rely on that? Seems to have done wonders for the biosphere for the last one billion years, hasn't it?
- toomuchtodo 4y agoYou are spot on. The world will be powered by renewables before fusion ever sees its first commercial watt produced. https://news.ycombinator.com/item?id=31428469 https://news.ycombinator.com/item?id=31428469 https://pv-magazine-usa.com/2022/05/16/a-fate-realized-1-tw-of-solar-to-be-deployed-annually-by-2030/ https://pv-magazine-usa.com/2022/05/16/a-fate-realized-1-tw-...
- nh23423fefe 4y agoInstead of asking oblique rhetorical questions, you could actually make a meaningful statement.
- gfodor 4y agoIt seems like every fusion post is bound to have at least one commenter point out that the sun is a working fusion reactor, as if literally anyone in these threads will learn something from this observation.
- toomuchtodo 4y agoRoughly $50 billion has been spent globally on fusion research since the 1950s with nothing material to show for the effort; at what point do you stop throwing good money after bad? This strikes me as the learning from these posts.
- dariusj18 4y agoI'm sure it is difficult to decide that since, as pointed out, there is a working example staring at us every day. So it always feel just out of reach.
- areoform 4y agoJust a quick reminder, we already have practical fusion with tens of thousands of years of runway available to us today. We choose not to do it because it sounds dangerous and it’s not politically expedient. For those unfamiliar, I am talking about Project PACER. The fusion reactor proposed by Teller after the creation of the thermonuclear weapon. It may sound fanciful but it’s based on a simple precept. We can already induce fusion reactions, albeit in an unstable and explosive fashion. What if we took that warhead, surrounded it with a giant underground chamber made out of steel several feet thick, and let it explode while molten fluoride captured the heat? Their work conclusively shows that this can be done, and that molten fluoride salts could capture most of the neutrons to prevent embrittlement. A single such facility could power the entire country. Oh and it could be configured to create Tritium in the process. https://en.wikipedia.org/wiki/Project_PACER https://en.wikipedia.org/wiki/Project_PACER The project was terminated because it was "bound to be controversial" and would "arouse considerable negative responses." The math is sound. The concepts are sound. We could solve the comparatively minor engineering challenges and build one today while waiting on the the breakthrough needed for controlled, continuous fusion.
- fffobar 4y agoIsn't the problem that the fuse for a fusion bomb is a fission bomb, and a fission bomb very violently disperses lots of radioactive material? What am I not getting?
- areoform 4y agoIt’s a sealed chamber underground. And the amount of fallout can be controlled. Some fusion designs are “cleaner” than others w.r.t. fallout. From the wiki, > A typical design called for a 4 m thick steel alloy blast-chamber, 30 m (100 ft) in diameter and 100 m (300 ft) tall,[9] to be embedded in a cavity dug into bedrock in Nevada. Hundreds of 15 m (45 ft) long bolts were to be driven into the surrounding rock to support the cavity. The space between the blast-chamber and the rock cavity walls was to be filled with concrete; then the bolts were to be put under enormous tension to pre-stress the rock, concrete, and blast-chamber. The blast-chamber was then to be partially filled with molten fluoride salts to a depth of 30 m (100 ft), a "waterfall" would be initiated by pumping the salt to the top of the chamber and letting it fall to the bottom. While surrounded by this falling coolant, a 1-kiloton fission bomb would be detonated; this would be repeated every 45 minutes. The fluid would also absorb neutrons to avoid damage to the walls of the cavity. You can see the general design here, https://nextbigfuture.s3.amazonaws.com/uploads/2016/01/zyrEF-1.png https://nextbigfuture.s3.amazonaws.com/uploads/2016/01/zyrEF...
- G3rn0ti 4y agoI thought the end game was aneutronic fusion using lithium and deuterium anyway creating only charged particles instead of high energy neutrons that are dangerous and damaging to the reactor. If nuclear fusion ever wants to be commercially viable, it must not depend on tritium.
- ncmncm 4y agoD-3He. But 3He comes only from decaying tritium, so same problem. At least D-3He might possibly be made to produce economically competitive power, if there were any 3He to burn in one. But it might be useful in space probes.
- silasdavis 4y agoWhimsy. Is there a sequence of fusion technologies where the previous one lights the next one and if the current one goes out we're fucked?
- DennisP 4y agoHelion is working on a deuterium/helium-3 reactor, which if it works will produce only 6% of its energy as neutron radiation. YCombinator was an investor. They've run six reactors and are building a seventh now for a net power attempt in 2024. There are also at least four companies working on proton-boron fusion, though all but one are very small. (TAE is the exception.)
- jszymborski 4y agoI'm not sure about the scale here, but is it really as crazy as the article says to use tritium that is formed from fission? What's the ratio of fusion:fission energy you'd need? I can't imagine even if it was 50% or 25% that it wouldn't be worth doing seeing as you'd just be fuelling a clean energy source from the waste stream of another energy source that doesn't produce CO2.
- marcosdumay 4y agoThe reaction is supposed to be self-sustaining. The reactor walls are supposed to emit more than enough tritium to satisfy your needs. Whatever you bring from outside is just to bootstrap it once you turn it on. (I imagine they are not collecting the tritium between runs, but it's something you are expected to do.)
- ASalazarMX 4y ago> The reactor walls are supposed to emit more than enough tritium to satisfy your needs. Didn't know that fusion generators produced its own fuel! If it produces more than enough, then the excess tritium is considered radioactive waste?
- fallingknife 4y agoNot really an issue though, as tritium has a half life of 12 years, and the amounts produced would be negligible anyway. You could probably release it into the atmosphere harmlessly (not that regulations would ever allow that, though).
- adrian_b 4y agoThe kinds of fusion generators that are considered for the near future produce most of their energy as kinetic energy of neutrons. The energy of the neutrons is transformed into heat by adsorbing them into some shielding walls. The materials for those walls will be chosen to minimize the quantity of radioactive waste that is produced by the extremely intense neutron irradiation, but it is impossible to avoid completely the production of radioactive waste. So all the fusion generators planned for the near future will generate radioactive waste, but in significantly less quantities than fission reactors of the same power. Because they produce an intense neutron flux, like the fission reactors, the fusion reactors can also be used for element transmutation by neutron capture, e.g. for producing tritium or for producing lightly-doped silicon crystals for the high-voltage electronic devices (by transmuting silicon into phosphorus). However, such transmutation applications usually also need the use of a neutron moderator, to slow the neutrons down to whatever speed is optimal for producing the desired isotope, e.g. tritium. For tritium, heavy water can play both roles, of the neutron moderator and of the target containing the element to be transmuted.
- rob_c 4y ago"tritium for its experiments". The whole point is to reach a Deuterium or Hydrogen reactor with a light lithium ignition in a lot of cases which would be easier to fuel than Tritium due do problems extracting it.
- howenterprisey 4y agoIf anyone was wondering if SPARC and ARC care about this, SPARC onsite tritium inventory is planned to be fairly low: just 10 grams (not kg) in this 2018 SPARC paper[0]. I would also speculate that 200 kg/year sounds a little bit too high, although I can't find an ARC paper to corroborate (the magic words you want are "total on-site tritium inventory"). [0] https://www1.psfc.mit.edu/research/alcator/pubs/APS/APS2018/Sorbom_APS_2018.pdf https://www1.psfc.mit.edu/research/alcator/pubs/APS/APS2018/...
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- theptip 4y ago> “It would be an absurdity to use dirty fission reactors to fuel ‘clean’ fusion reactors,” This seems like a non-sequitur. If we need to keep around (or even build) a few heavy-water fission plants to enable the fusion industry, what's the problem? The simple phrasing of fission as "dirty" really shows the quotee's biases. You could easily envision a stable energy mix with a few percent of fission, the rest fusion and storage/peaking power, and that would be far, far cleaner than our current GHG/pollutant-heavy mix of fossil fuels. It seems quite premature to call this a "crisis" since we already have proven ways of manufacturing the required ingredient. I suppose the risk is just that this pushes up the price of fusion in the initial phases of deployment, providing an "activation cost" that delays fusion from taking over, but that's quite a speculative concern at this point.
- 99_00 4y agoThere's a lot of bad thinking in that one sentence. All or nothing. We must have completely clean power or it has no value. Not using comparison. How does it compare to other sources of energy, (including solar which is built in facilities using coal power).
- zitterbewegung 4y agoFission is much cleaner than coal power plants in the Nuclear isotopes that are released into the air and we can contain nuclear waste pretty well.
- ncmncm 4y agoCoal is on its way out, so is not a sensible standard of comparison.
- JimTheMan 4y agoAt some point, we will have enough solar/hydro/wind etc that they won't be built using coal power... Right now it's a necessary yes, in the future no. In a way, that last (...) is also a very black and white way of viewing things.
- westcort 4y agoMy key takeaways: * In a perfect world, there would be a more ambitious program developing the breeding technology in parallel to ITER, Willms says, so that by the time ITER has perfected the fusion reactor there’s still a fuel source to run it * Like many of the most prominent experimental nuclear fusion reactors, ITER relies on a steady supply of both deuterium and tritium for its experiments * When it’s finally fully switched on in 2035, the International Thermonuclear Experimental Reactor will be the largest device of its kind ever built, and the flag-bearer for nuclear fusion * And as ITER drags on, years behind schedule and billions over budget, our best sources of tritium to fuel it and other experimental fusion reactors are slowly disappearing * Right now, the tritium used in fusion experiments like ITER, and the smaller JET tokamak in the UK, comes from a very specific type of nuclear fission reactor called a heavy-water moderated reactor * “We’re hitting the peak of this tritium window roughly now.” Scientists have known about this potential stumbling block for decades, and they developed a neat way around it: a plan to use nuclear fusion reactors to “breed” tritium, so that they end up replenishing their own fuel at the same time as they burn it * “Calculations suggest that a suitably designed breeding blanket would be capable of providing enough tritium for the power plant to be self-sufficient in fuel, with a little extra to start up new power plants,” says Stuart White, a spokesperson for the UK Atomic Energy Authority, which hosts the JET fusion project * “It would be an absurdity to use dirty fission reactors to fuel ‘clean’ fusion reactors,” says Ernesto Mazzucato, a retired physicist who has been an outspoken critic of ITER, and nuclear fusion more generally, despite spending much of his working life studying tokamaks * “After 2035 we have to construct a new machine that will take another 20 or 30 years for testing a crucial task like how to produce the tritium, so how are we going to block and stop global warming with fusion reactors if we will not be ready until the end of this century?” says Mazzucato Arthur Turrell's book, The Star Builders, is an excellent overview of the state of the art of nuclear fusion technology. Unfortunately, however, fusion is unlikely to be radically cheaper than other sources.
- gitfan86 4y agoLast week Elon explained that the problem of fusion is that it will be more expensive than solar and wind.
- dhosek 4y ago>in, … 12.3 years…, half of the tritium available today will have decayed into helium-3. When I saw this, I thought that sounded odd, shouldn’t the atomic number go down with radioactive decay? but it turns out that in this case what happens is one of the neutrons splits into a proton, an electron and an electron neutrino so the atomic number goes up by one (unlike the more familiar fission reactions of the heavier elements where the atomic number decreases). So much physics I’ve either forgotten or never learned.
- db48x 4y agoYea, beta decay is weird. On the other hand, transmutation of the elements!
- adrian_b 4y agoThis is the standard beta radioactive decay, which increases Z by 1, while the alpha radioactive decay decreases Z by 2 (and gamma decay does not change Z). For every A (the number of nucleons in a nucleus) there is a ratio between (A-Z) and Z (i.e. between the number of neutrons and the number of protons) for which the mass of the nucleus is minimum. Any other isobaric nuclei have an excess of mass over the nucleus with the optimal neutron/proton ratio, so they will decay towards it. The nuclei with too many protons will capture electrons or emit positrons, while the nuclei with too many neutrons will emit electrons, increasing the number of protons with each emitted electron, until the optimal neutron/proton ratio. For the decay products of uranium and thorium, there are always too many neutrons, so the normal beta decay is what always happens. It is possible to artificially produce nuclei with too many protons, and there are a few such unstable isotopes that are produced naturally, which decay by the reverse beta decay (electron capture or positron emission), where Z decreases by 1 for every captured electron / emitted positron. For A = 3, the nucleus with minimal mass is helium-3. Tritium has too many neutrons in comparison with helium-3, and it must get rid of them by emitting an electron.
- somenewaccount1 4y agoTitle is extremely misleading. > "Right now, the tritium used in fusion experiments like ITER, and the smaller JET tokamak in the UK, comes from a very specific type of nuclear fission reactor called a heavy-water moderated reactor." You litterally just need to make more of these heavy-water moderated reactors, which are rare and approaching end of life, but certainly you can build more of them if it was the difference between having endless energy or not.
- dang 4y agoOk, we've changed the title to the subtitle above.
- jmyeet 4y agoITAR should be shut down. Straight up. It's a complete waste of taxpayer funds taht holds no prospect of producing commercially viable power. Its design constraints were decided decades ago. Since then science and engineering has advanced a lot. I'd love if it fusion became commercially viable but I'm doubtful it ever will. At the least the kind involving fusion atoms in a plasma for all the documented reasons, most notably plasma turbulence and the power loss and container damage from neutron escapes. I'm not that concerned about a shortage of tritium. That's a solvable problem. In fact we probably need a variety of breeder reactors for things like this and producing plutonium for deep space probes anyway. Fusion is a trap for many because it seems so easy. I mean the Sun is doing a lot of it. But the Sun is relatively inefficient (which is compensated for by mass) and it solves the containment problem with gravity.
- credit_guy 4y agoWell, for all practical purposes, ITER was shut down. https://www.world-nuclear-news.org/Articles/ITER-tokamak-assembly-put-on-hold-by-regulator https://www.world-nuclear-news.org/Articles/ITER-tokamak-ass... https://www.reuters.com/article/us-france-nuclear-fusion/iter-nuclear-fusion-project-faces-new-delay-cost-overrun-les-echos-idUSKCN0XT0LY https://www.reuters.com/article/us-france-nuclear-fusion/ite...
- Stevvo 4y agoOne of the main objectives of ITER is to test Tritium Breeding technologies for DEMO. There is no shortage due to heavy water plants shutting down because it was never planes to use Tritium from that source in the first place!
- pfdietz 4y agoITER will not produce significant tritium, since most of its walls are not covered with breeding blankets. Most of the neutrons it produces from DT fusion will not hit a blanket module and therefore not breed tritium.
- hajile 4y agoWasn't this the setup for Spiderman 2?
- ncmncm 4y agoIronically, this is perhaps the smallest problem facing practical civil fusion power. Probably the biggest problem is wasting time and budget on such dead-end technology as Tokamak, which can never in anybody's wildest dream be competitive with renewables, even given abundant tritium. But the conceivably useful D-3He aneutronic fusion depends on a supply of 3He, which is uniquely a product of tritium decay, and thus also depends on a tritium supply. Thus D-3He would not be useful for baseload civil power, either. But it could be the only useful power source for projects in the outer solar system, for which a much smaller amount of 3He would suffice. It is hard to imagine another power source adequate in the outer solar system (aside from pB11 fusion which would be super if it is actually possible at all). (No, mining 3He from the moon would totally not work at all.)