General Fusion to build demonstration plant in UK
bbc.co.uk
bbc.co.uk
Perspective given in the article belittles great strides made by fusion pioneers and poisons discussion on public policy:
Fusion has advanced faster than Moore's law - and unlike the holy grail of computing, true AI, it's now clearly within reach. https://www.reddit.com/r/pics/comments/hsmge/moores_law_for_...
>"Frustrated by the slow progress, private companies [innovate]"
This is not about frustration, it's about opportunity:
After decades and billions spent on research and engineering, all "open source", and training a generation of plasma scientists, venture capital can hire these people into profitable ventures. I'd like to ensure these people are given proper credit, and actually make some money off their great contribution to humanity.
I fear that all we will do to reward greatest minds is give them mediocre jobs.
Figure 1 has an update showing that the exponential trajectory has stalled.
Edit: https://www.sciencedirect.com/science/article/pii/S254243511...
Figure 1 has an updated version, and it is rather bleak.
I don't have the knowledge to judge how much of this slowdown is due to the ITER project being international and difficult to manage, and how much of it is due to us approaching the limits of what is physically possible.
However it's good to keep in mind that our level of funding for fusion is pathetic and scientists themselves have categorised it as "fusion never"
https://upload.wikimedia.org/wikipedia/commons/a/ab/U.S._his...
A pretty simple model that accounts for the data is that Moore's law, and many other exponential growth examples, require ever larger capital expenditures. This worked for Moore's law because at ever step of improvement the devices produced were highly economically valuable. For fusion, on the other hand, you can have an exponentially improving triple product, but it has zero economic value until you cross the net-positive threshold. That basically means that the exponentially increasing development funding needs to be provided by the government, philanthropy, or some other non-profit source. If you're exponentially improving, with exponential costs, and you hit the ceiling of what the government and philanthropists are willing to provide, your progress can come to an abrupt halt without it necessarily meaning the basic exponential engineering curve you were following stops.
But we don't actually have exponential improvement in any physical object, that's not to do with information processing - a solar panel or battery made today is not 10x better than one made 10 years ago.
It's not even true of all semiconductors - power electronics, radio, etc.
Do you understand how differently that reads from your original comment?
> Fusion has advanced faster than Moore's law - and unlike the holy grail of computing, true AI, it's now clearly within reach.
You made the claim it's advancing at a rapid rate and almost here, and when someone pulled up the data it wildly disagreed with you. Now you're just moving the goalposts.
Fusion is usually more about electromagnetism, though.
"The national fusion programs progressed well during the Cold War because of fierce international competition. They have stopped moving forward in the late 1980s because the decision to consolidate them all into a single global project, the International Thermonuclear Experimental Reactor (ITER), removed all stimulus for action. Indeed, it too, nearly a quarter century for the bureaucrats in charge of ITER to manage to reach a consensus in 2010 on where tu put it, and it will be another quarter century before the machine even attempts to reach thermonuclear ignition in 2035"
Low chance it would have made the Hacker News front page if it did. Unfortunate as it is, the newsworthy component is Bezos's endorsement. Otherwise, it's another fusion start-up.
Wouldn't the comparable speed be how quickly we got from no solid state transistors to making our first chip?
It’s why they will also throw in other large brand names and stock tickers of entities that could be of the slightest relevance
A large chunk of media traffic comes from Google alerts for large brands…so the writers try to game the system here
i wonder whether (and how) they can do it better than the explosive lens of the fission primary. I mean they have to do it better as otherwise there wouldn't be need for the fission primary.
There are fast nuclear reactors which use lead-bismuth for the coolant ( the Soviet Alfa class submarine used them to mixed success, but that was in the 80s), so maybe there are alloys with fitting temperature characteristics?
It's basically the hottest plasma we can make suspended in a magnetic donut surrounding by near absolute zero temperatures.
Also, per unit volume, the sun produces about as much power as a compost pile.
In fusion on earth, we want to be considerably more efficient than the fusion process in the sun, as we don't have as much space to work with. ITER is already a pretty big machine.
We still have plenty of helium. It's a byproduct of oil extraction and is still often vented because it would not be profitable of capturing it.
Certainly not in the conventional sense (although perhaps there's another way that helium might act similarly to a GHG that I'm not aware of).
Greenhouse gasses are molecules, i.e. multiple atoms bonded together. Those molecules can absorb photons of infrared light, which cause them to vibrate (as if the atoms were held together by springs). After some time, the vibration stops and an infrared photon is emitted.
The problem is: those photons are emitted in a random direction, unrelated to the photon that was absorbed. Half the time they will go roughly upwards, half the time they'll go downwards.
A photon of visible light (from the Sun) can travel down through the atmosphere without interacting much with the greenhouse gasses, since it has too much energy to be absorbed. This visible photon can be absorbed by other materials at ground level, e.g. by a plant, and its energy will eventually result in around 20 lower-energy infrared photons being emitted back up (on average).
These 20 infrared photons are readily absorbed by the greenhouse gasses, and each time they're absorbed, they get re-emitted in a random direction: half the time heading upwards again, but half the time heading back to the ground. This is how energy gets "trapped" by greenhouse gasses.
Helium is almost completely unreactive: it doesn't form molecules in the atmosphere, it just bounces around as individual atoms. Without bonds to vibrate (or asymmetries to spin), the only way it can absorb energy is by speeding up, and even this isn't very effective since its mass is so low. Fast-moving helium is also more likely to escape the Earth's gravity completely.
The frequency band for absorption and emission might be different, but the helium could absorb a shorter wavelength, then release a longer wavelength (not infrared) that can be absorbed by something else, then emitted yet again to be infrared
The lower the temperature, the higher your critical current is for a given superconductor. The reason HTS are a big deal isn't that you can have a superconductor at liquid nitrogen temperatures, but that you can have a very high field at liquid helium temperatures.
Fusion in theory has no pollution at all, but that's theoretical until large scale fusion plants are built.
Of course, repairing things inside a fission reactor is no less nasty, but fission reactors are comparably much simpler and much smaller. Swapping a fission reactor out with a new one is comparably much easier than with a fusion reactor.
MIT's Commonwealth uses an inner wall that's 3D-printed and designed to be replaced annually. They've tested joints in their superconducting tape, which will let them open up the coils on hinges so they can drop in a new inner wall. They'll surround that with liquid beryllium/lithium as coolant and breeding blanket.
Fission requires effort to control. When things go wrong it isn't controlled.
Fusion requires effort to create. When things go wrong it isn't created.
Yes, they are massively energetic, (we wouldn't be harvesting power from it if they weren't.) However, they require a very high input energy to trigger the release of the output energy.
With a fission reactor meltdown, the way you get there is by pulling out dampening rods or boiling off all the water, but otherwise leaving the fission rods in the same place.
With a fusion reaction, you have to be constantly providing both the energy to keep the fusion going AND the input material to be fused. Interrupt one or the other and fusion stops.
I know it seems weird that the bigger energy release is safer, but that's how it is. It's the difference between requiring constant input into the system to produce power vs an idle system with no input producing power.
I'm not trying to scaremonger fusion energy, but I think it's intellectually dishonest to portray is as fundamentally sound, with a binary outcome of either inertia or safe energy. This design relies on spherical compression to both initiate and confine the fusion. We should not discount the possibility that if it instead creates a cylindrical or elliptical confinement due to malfunction, it will just explode, at a minimum destroying the device. We know it is possible to initiate fusion with radial compression in a cylinder, because that's how an H-bomb secondary works.
The main safety factor in these things comes from the fact that a fusion weapon needs hundreds of kilos of hydrogen, and they are experimenting with much smaller masses. That limits the destructive potential.
1) There isn't a reality in which these devices get scaled up to that size. 2) The real danger with fission is radiation, not explosions, which fusion reactors will produce in smaller quantities than a banana farm.
Pure fusion power, even in its largest, most powerful, Elon Musk fever-dream incarnation, is safer than even the safest fission reactor, because there is no way for it to create a boom larger than it's vessel was designed to produce.
No offense but I think this sentiment is a huge problem with Hacker News. I have a minimal understanding of fusion energy production from an engineering perspective but I know more than the vast majority of the world due to my background.
You are smart but not a subject matter expert in this topic. Fusion is not a sustainable a reaction while fission is. Fission happens on its own, fusion requires something else to happen first (on Earth). Please don't insult the people in this thread who are subject matter experts in the field by implying they are intellectually dishonest. I am not a subject matter expert but recognize that a few of them are commenting in this thread with details that I have learned from other experts.
The reaction itself kicks off a huge amount of neutron radiation, which eventually makes the reactor chamber radioactive - that is the only radioactive waste that will have to be disposed safely eventually. But neither the fuel nor the resulting product are radioactive.
I don’t think the reactor would be scrapped, just shutdown for maintenance.
So most of the heat will have to be extracted from a radioactive material, with similar precautions like in fission reactors, where the heat is extracted from the radioactive nuclear fuel.
I am very skeptical that fusion of deuterium with tritium or of deuterium with deuterium will ever produce "clean energy", even if they are the easiest fusion reactions, due to the relatively low temperatures required for them.
It still remains to be proven whether the radioactive waste for a fusion reactor of the kinds attempted now will be less than for a fission reactor.
I wonder, how can this possibly be even a question? Fission based reactors obviously have the same or worse problem of irradiating the entire reactor enclosure and everything around it, so that's at best the same as a fusion reactor + they produce tonnes of very highly radioactive waste that will be radioactive for millennia.
Materials activated through neutron bombardment aren't radioactive for anywhere near as long. And to add to that, nearly all elements produced in a fission reactor are highly toxic in addition to being radioactive - in a fusion reactor if your steel containment chamber becomes activated, you just have radioactive steel, not one of the many many dangerous heavy metals produced through fission.
LFTR would be far better. Neutrons breed new fuel, and it consumes virtually all the radioactive fuel with "waste" that rapidly becomes non-dangerous within a month.
So I would guess neutron degradation of the equipment/vessel/reactor will probably be a similar problem in both cases.
IIRC people have stated that the breeding could also reprocess the bad millenial-scale waste from LWR into usable fuel or other isotopes in MSRs, although maybe not in LFTR.
If we had a decent LFTR industry, we could probably have more specialized MSRs to deal with the "legacy" waste and breeder reprocess into new fuel or other stuff.
The chemists from ORNL seemed pretty amazing. They had all the work done for separating out the byproducts for use in other applications.
Fission byproducts are well known to just be a ton of heavy metal junk that decays over thousands of years.
I'm sure there's fusion byproducts that are nasty too, but fundamentally you can't get byproducts as high up on the elemental chart as you can with fission strictly because fusion is merging 2 smaller atoms into 1 larger atom. With fission you start with a larger atom and break it into 2 smaller ones. Oversimplified, but you get the idea.
- Method to Reduce Long-lived Fission Products by Nuclear Transmutations with Fast Spectrum Reactors https://www.nature.com/articles/s41598-017-14319-7
- Fast-neutron reactor https://en.wikipedia.org/wiki/Fast-neutron_reactor
- Evolution of transuranium isotopic composition in power reactors and innovative nuclear systems for transmutation https://inspirehep.net/literature/1243003
And few other things. It is possible to have nuclear power with shorter byproducts than thousands of years.
Newer reactors and spent fuel reprocessing are definitely ways to solve the issue, but the fact is you still create those nasty byproducts in the traditional reactors today.
[1]: https://en.wikipedia.org/wiki/Nuclear_power_in_the_United_St...
With a fission reactor you have to expose uranium to those neutrons and when it gets hit it either splits into dangerously radioactive components or absorbs a neutron and becomes dangerously radioactive plutonium. There are pipes and stuff that become a bit radioactive too but that's not the part that people are afraid of when an accident happens. Also, the dangerously radioactive byproducts continue to release a lot of energy after the chain reaction is shut down, about 10% of the power the reactor was run at. So even after a fission reactor is shut down you need to keep cooling it otherwise things melt and people become unhappy.
With fusion you do need to keep exposing lithium to the neutrons from the reaction to make more tritium fuel. And tritium is radioactive. But if it escapes it'll go straight up into the upper atmosphere where it won't particularly bother people and then dilute. You've still got the radioactive pipes problem you do with fission but, again, that's not really the part that people are afraid of. And once you stop containing the plasma energy generation stops instantly.
I'm generally inclined to say that the risks involved in fission are worth the benefits but those risks are worth taking seriously and require careful government regulation more so than other forms of power. With fusion, on the other hand, I'd a lot less concerned with someone building a power plant up wind of me than a coal plant even with similar levels of regulation. Just as long as they aren't deliberately exposing uranium to the neutrons or something like that.
Pneumatic pistons? How is air pressure even close to enough force to make the slightest difference to a fusion reaction?
It's great to see non-tokamak designs being developed
https://generalfusion.com/technology-magnetized-target-fusio...
There's a longer video on that page as well with more details.
The BBC article is simplified a bit too far for anyone with a technical background but I doubt if a more accurate version would be much more meaningful to most people.
There is a patent on it: https://patents.google.com/patent/US9424955B2/en
----Quote:
2. Description of the Related Art Various systems for heating and compressing plasmas to high temperatures and densities have been described. One approach for accomplishing plasma heating and compression by spherical focusing of a large amplitude acoustic pressure wave in a liquid medium is described in U.S. Patent Publica tion No. 2006/0198486, published Sep. 7, 2006, entitled “Pressure Wave Generator and Controller for Generating a Pressure Wave in a Fusion Reactor”, which is hereby incor porated by reference herein in its entirety. In certain embodi ments of this approach, a plurality of pistons is arranged around a substantially spherical vessel containing a liquid medium. A vortex or cavity is created in the liquid medium. The pistons are accelerated and strike the outer wall of the vessel generating an acoustic wave. The acoustic wave generated in the liquid medium converges and envelopes a plasma that is introduced into the Vortex, thereby heating and compressing the plasma.
----end quote
Huh? Pneumatic pistons?
I think they may have moved away from that in favor of big pneumatic pistons pushing tiny piston heads directly into the liquid though. Mechanical advantage is the area ratio, which you can easily make quite large.
It takes about one second for 1 megawatt to boil three litres of water.
The pulsed fusion system will produce a huge peak power output but only for an extremely short time. They design the system so that the total heat output is absorbed by the lead mass. The other constraint is the lead needs to be thick enough to absorb the vast majority of the radioactive particles before they reach the machine.
So a lot of alternatives, like SPARC, General Fusion, Lockheed, Tokamak Energy, Commonwealth Fusion, ... are all aiming to demonstrate in 2025 as well, because it will contrast nicely to the ITER approach costing a lot of government money. Anyone that will beat the Q of iter in 2025, might see more government funding flowing their way between 2025 and 2035, because they managed to do the same, but orders of magnitude cheaper.
ITER is mostly a giant experiment in programme management. One could argue that it is the most complex machine built so far by humanity, way more complex than e.g. the LHC or Ligo or ISS. 2025 might give us an upperbound on the complexity of machines humanity can manage with our current society.
>Funding flowing their way between 2025 and 2035,
So they will need another round of funding to 2035, which means even the most optimistic outlook we wont see one operation until something like 2045?
Commercially viable fusion is not for before 2045, but its MVP might be there in 2025, if one is really optimistic.
The Sun is a self-sustaining fusion plasma that already exists. It is confined by its own gravity. It will continue running at a steady state for billions of years. Except for melanomas, this source of power is completely harmless to human life.
In order to plug this thing into the electric grid, all we need to do is capture the free electromagnetic emissions of the Sun. We already have this technology, called a photovoltaic cell. The production of such cells is an industrial engineering problem. There are no technological barriers.
Compare to "fusion power", for which the ignition, confinement, and exploitation of the energy are all totally unsolved technological problems.
I could be wrong though, I'm not an expert.
[1] https://spectrum.ieee.org/energy/the-smarter-grid/lets-build...
TLDR: Despite recent progress, is it possible that fusion will reach efficiency where it is net positive in energy output but still too expensive to be useful?
Long Version: When I first heard about fusion, the idea was that this immense energy could be harvested taking advantage the the conversion of matter into energy. Everything I heard was that the quantities are so great that if we could just nail the sustained fusion reaction we could harvest potentially limitless energy.
As I've come to understand it however, it is not so simple. The big question is in how long you can sustain the reaction and how much energy it costs to start it in the first place. It seems to me the strides that have been made over the last few decades are to bring the cost down enough and extend the reaction long enough that the net energy loss is lower, then break even and now possibly a net gain. I've seen some articles imply that this turn of events means fusion is definitely on the table as a near future abundant energy source.
My question is this. Is it a forgone conclusion that the current trends will continue? Because if not, doesn't that mean fusion could still get stuck somewhere where there is a net energy gain but it's still too expensive to be useful?
The first generation of fusion reactors will be expensive and monolithic, but we will learn a lot from them and it will prove their fundamental functionality.
The second generation reactors will likely be using better fuels and squeezing plasma into different shapes to keep them running as long as possible.
Even if other renewable energy sources continue to get cheaper and become prolific, they still have the problem of energy storage. Simply put, we don't have anywhere near the resources required to build all that storage. So what we need instead is a solid mainline energy source (nuclear and fusion).
In the case of a massive breakthrough in energy storage, at best it will just delay fusion power. We will still need to use fusion off planet.
Sources?
There are lithiumfree batteries, made from cheap metals. Saltwater batteries for example.
Airpressure as energy storage.
Hydrogen or more processed into methanol ....
Etc., etc. all working technology as of today. And sure, sure, storage comes with lower efficency, but there is no reason, we cannot transform the various deserts into big solarplants.
Fusion would be awesome to have. But I see no indication, that it will be ready anytime soon, when we need it, to produce clean energy at scale. And if it is ready, we probably still need resources, like Helium-3. Ready to mine the moon?
If solar+batteries can outcompete fossil fuel plants (while ignoring fuel costs), then fusion likely wouldn't be viable commercially. And if you look at [the data](https://en.wikipedia.org/wiki/Cost_of_electricity_by_source#...), we are already close to this point.
This is very likely and expected. First we need that positive output - then we can improve and scale up .. and then it might be worth it.
ITER was designed with LTS coils and will cost in the range of 50 billion USD. HTS coils are a big deal for driving size and cost down. MCF is still the king in terms of fewest engineering hurdles to overcome. Mirrors and liquid metal pistons are certainly neat avenues and should be explored, but you won't see them in 1st generation plants.
It's all fine to do this as a research project. But this is not a technology that is going to solve our energy problems any time soon - and it certainly shouldn't distract from deploying the solutions that exist today, aka mostly wind+solar.
If it doesn't generate power, what does it do? Will fusion happen there? Why does it need to be 70% of size of a "commercial reactor" if it isn't one?
I feel like I am less I formed about this project than before I knew it existed...
That surprised me. At 70% of the size for $400M, I wonder why they didn't just try to build a commercial reactor in one go
Is this the a mid-step between a small demo and a full reactor? What do they do with the building after they've tested it?
They don't know exactly how to build a commercial reactor yet. The scale they've worked at so far tests the basic design but it can't break even (no fusion reactor has yet) or function continuously. They are going to build the minimum size that they think will achieve these goals but it will also have to be capable of testing to be able to fine tune operation. A commercial reactor wouldn't be built like that.
Also, keep in mind that cost doesn't scale linearly. Likely cost goes up with the cube of the size or higher.
This isn't a criticism of them btw - it's exactly the sort of thing we should be subsidising - but it may explain it.
https://en.wikipedia.org/wiki/Culham_Centre_for_Fusion_Energ...
they are back to sell theirs ;)
i knew it, wrote about it few years ago here
https://www.amazon.com/Paradox-Eternity-Phillip-P-Peterson/d...
When I invest in an ice cream cone, that ice cream is about to be destroyed and my investment will soon be down the toilet, but I was certainly participating in the market. If Bezos's reactor blows up, it will be little bits of the free market raining down. And if it powers the world with endless green energy, there will be little green energy free market electrons pumped across the world.
We'd be better off just coming up with good fast breeder reactor designs that have good safety measures. A breeder reactor can burn its fuel completely, it's a tried and true technology and it's our best shot at eliminating fossil fuels.
The fusion research is important science, and I completely support researching it, but it's not a technology that's going to be commercially useful in our lifetimes and it's not better or cleaner technology than modern fission reactor designs.
[1] https://thebulletin.org/2017/04/fusion-reactors-not-what-the...
> Solar and wind power alone can’t scale up fast enough to generate the vast amounts of electricity that will be needed by midcentury, especially as we convert car engines and the like from fossil fuels to carbon-free energy sources. Even Germany’s concerted recent effort to add renewables—the most ambitious national effort so far—was nowhere near fast enough. A global increase in renewables at a rate matching Germany’s peak success would add about 0.7 trillion kilowatt-hours of clean electricity every year. That’s just over a fifth of the necessary 3.3 trillion annual target.
> To put it another way, even if the world were as enthusiastic and technically capable as Germany at the height of its renewables buildup—and neither of these is even close to true in the great majority of countries—decarbonizing the world at that rate would take nearly 150 years.
[1] https://www.wsj.com/articles/only-nuclear-energy-can-save-th...
Any idea what the bottleneck(s) is/are?
The UK has not brought a new (commercial/public power) nuclear reactor online since the nineties, or finished building a completely new site since the eighties.
It has started building one, which is over budget and delayed and has been described as “the most expensive power station in the world”.
It has had three recent plans cancelled, four more go nowhere in years, had two developers (EON and nPower) pull out of UK nuclear, and the Scottish parliament had backed no new nuclear plants in Scotland.
If nuclear is our saviour, it’s not looking very likely that we’ll be saved.
Massachusetts, in the Northeast, is showing a real-world strategy for solar.
Massachusetts incentivizes homeowners to have their own solar installs. My house, for example, has solar, as do many houses in my town. Yesterday it produced about 50 kWh, meaning I was sending energy into the grid.
You might ask, what's the point of solar if there's no storage? Going 100% renewable would be amazing, but reducing CO2 is a win. If electric load declines because more and more homes can produce their own electric, that's a huge reduction in total CO2 that needs to be produced at the power plants. It doesn't mean we can throw away the gas plants, but they can be run at lower capacity. Storage isn't really discussed yet, but maybe one day we'll get there.
We're also investing in a huge offshore wind farm.
I think this highlights the bias in the article you shared. Moreover, it solely focuses on ITER which is not a great example any more.
Fusion doesn't really have the problems of fission. Because fusion has been extremely underfunded, the money is being spent extra carefully on ITER. But MIT SPARC is using new super conductors to get much smaller reactors.
Reactors will produce some low level waste, but once we get a handle of the confinement, that issue can be eliminated with hydrogen isotope mixes. Also, Tokamak is only one fusion design, there may be better ways to capture the neutron stream.
We already have fusion bombs. Building fusion reactors wouldn't impact nuclear proliferation at all. I really can't think of a single fusion reactor design that produces "nuclear weapons material." If fusion designs made nuclear material, then we'd probably already have nuclear-material-producing fusion reactors.
I find it strange that you think breeder reactors are the way to go. Fusion's challenges are rooted in engineering - creating magnetic fields, heating plasma, breeding tritium. Fission's challenges are in public sentiment, exuberant costs, and dealing with extremely toxic metals.
> it's not better or cleaner technology than modern fission reactor designs
The "nasty ingredients" in fusion are deuterium, tritium, lithium, and irradiated confinement metal (think eutectic materials like stainless steel). The "nasty ingredients" for fission are much, much worse - both in products and required inputs.
Fusion promises energy generation without the high atomic count; this makes the inputs easier to acquire, the risk of catastrophe much lower, and allows more flexibility in design (scale, cost, efficiency targets).
I'd argue that a lot of the public sentiment problems with nuclear were PR'd into existence by the insanely powerful and wealthy fossil fuel industry to which fission is a very real existential threat. If we're talking about exuberant costs, fusion beats fusion hands down and has yet to deliver a single net watt of power. The waste disposal is more of a political problem than a technical one.
Overall, the problems with fusion are hard technical problems, and the problems with fission are self-imposed political ones pushed by the fossil fuel extraction industry that fission could very realistically replace.
Fusion power has indeed had high R&D costs, but so has any significant project before the ROI starts to kick in. Fusion power (especially the types that don't generate a neutron flux) is safer and more productive in principle compared to fission, and I have high confidence I will live to see a commercial fusion reactor come online in my lifetime.
As to more sort term concerns, fission has a lot of very expensive requirements like 24/7/365 security which make it difficult to integrate with vastly cheaper renewables. Baseline power sources like nuclear and coal wind are at a massive disadvantage when integrating with significantly cheaper wind and solar. They lose significant amounts of money during part of the day and need much higher premiums the rest of the day to make up for it.
In today’s energy market there is definitely a place for fission. However, with a 50 year payback period you need to project into future energy markers with even cheaper solar, wind, and batteries. That’s why electricity companies generally view it as a dead end. Fusion is a larger unknown, it’s probably not going to be cost effective but it’s also the kind of long shot that might just pay off.
Yeah, sure, if we're gonna get a big spaceship to even a small fraction of light speed, that would require absolutely stupendous amounts of energy.
But lets worry about that after we avoid cooking ourselves with GHG emissions? We might or might not have enough fission fuel for large-scale interstellar travel, but certainly more than enough to get rid of fossil fuels.
> fission has a lot of very expensive requirements like 24/7/365 security
So will fusion, unfortunately, unless someone figures out aneutronic fusion, which is a much longer shot than D-T fusion most efforts are concentrating on.
I'm all for spending a lot more on fusion R&D though; the potential win is just so enormously large that it makes sense to bet some amount of resources on it, just in case it works out.
Since a fusion reactor would produce an intense neutron field, it doesn't take a genius to figure out that if you line the reactor vessel with natural uranium, you have a device for producing plutonium. That is by no means a showstopper, but it means fusion plants will need 24/7 security, IAEA inspections, worries when/if suspicious tinpot dictator states decide that they will need their own fusion power plants, etc. etc. Even if we'd magically solve the technical challenges in fusion, we won't be seeing things like dinky fusion-powered ships sailing around the oceans (for larger ships, one could envision some kind of IAEA monitoring system for those).
Of course, if someone figures out aneutronic fusion (pB11 or such), these proliferation concerns would evaporate. That's a pretty big if, though.
> dealing with extremely toxic metals.
Spent fuel, in particular, is certainly radiotoxic, but chemically, no, not that big of a worry. Society routinely deals with other toxic heavy metals like lead as well, not to mention all kinds of other extremely toxic compounds.
Fusion power plants would also be a terrible place to irradiate uranium. Getting material in and out would be a total hassle and you wouldn't necessarily be able to control the reaction.
Yes but you only have to worry about radioactive reactor parts and other structural materials, not spent fuel.
> still capable of producing nuclear weapons material,
I don't get this argument at all. A fusion reactor does not generate heavy elements such as uranium or plutonium. However, the fusion reaction can be a neutron source which could be used to convert heavy elements such as thorium or uranium into fissile material. But by no means would this be part of any power generation station. This leads us to...
> We'd be better off just coming up with good fast breeder reactor designs
So this neutron source is somehow more clean and secure than the other one you just dismissed?
- Fusion produces much less radioactive waste byproducts then fission. It's not zero, but it's a significant difference.
- The problems with nuclear weapons proliferation are much easier to handle with fusion. For starters, you're not transporting enriched uranium fuel around. Also you don't end up with fun transuranics like plutonium which can be readily used to make weapons, unlike any key byproducts of fusion. Hell, the main byproduct of our fusion reactors is gonna be Helium, which we actually need more of because it is a very useful element that experiences shortages due to not being contained in the atmosphere and not being super prevalent in the earth's crust.
- "Extremely fussy" is a selling point. Extremely fussy means that if something goes wrong you don't have a runaway chain reaction that makes everything go boom. It's impossible to design a fusion reactor that can melt down. Meanwhile, melting down is the default mode for fission reactors and needs to be carefully designed around.
- Fusion is the only viable energy source for long-term space travel/colonization.
- The point about net energy surplus is kinda nonsensical. Of course we're not there yet, that's why it's a problem we're actively working on and not something we've already solved. Your point is literally "we shouldn't develop this technology because we haven't developed this technology yet".
Also not sure how we can simultaneously need to "come up" with a good fast breeder reactor design while at the same time it's apparently "tried and true technology".
Sorry, I should've elaborated a bit on this point. I'm talking about the expensive containment system which will be subject to extreme conditions and have a short lifetime[1].
> Under reactor-relevant conditions, the following are the most serious damaging mechanisms: thermally induced defects such as cracking and melting of the plasma-facing material (PFM); thermal fatigue damage of the joints between the PFM and the heat sink; hydrogen-induced blistering; helium-generated formation of nanosized clusters; and neutron-induced degradation of the wall armor via reduction of the thermal conductivity, embrittlement, transmutation, and activation.
> Further serious lifetime-limiting PWI processes are caused by material irradiation with hydrogen isotope ions (D+ and T+) and impurities that—depending on their impact energy—will sputter the wall material. The eroded species will be deposited elsewhere, for example, on unshielded parts of the vacuum vessel, on blanket modules, or on less severely exposed divertor targets (outside the separatrix strike zone). Implantation of hydrogen isotopes into the surface of the PFM will result in severe embrittlement of the wall. This also has a strong impact on its cracking resistance, in particular during short transient thermal loads (i.e., ELMs). Helium will also be implanted into the surface of the wall armor or buried in redeposited surface layers. Implanted helium tends to migrate (depending on the prevailing temperature) and to form tiny bubbles that again can interact with implanted hydrogen. In several fusion-relevant PFMs (e.g., tungsten) helium can initiate rather substantial changes in surface morphology, such as the growth of tiny tendrils or “fuzz” on the surface of the PFM.12 These layers can easily reach several micrometers in thickness. These effects need to be considered as a potential source for the release of dust particles and contamination of the burning fusion plasma.
So I'm not talking about the fail-safe nature but rather the extreme cost and technical difficulty of containing the reaction for the amount of time that would be needed for fusion to be a viable commercial energy source.