[HN Gopher] Fusion startup plans reactor with small but powerful...
___________________________________________________________________
Fusion startup plans reactor with small but powerful
superconducting magnets
Author : rbanffy
Score : 184 points
Date : 2021-03-05 18:18 UTC (4 hours ago)
(HTM) web link (www.sciencemag.org)
(TXT) w3m dump (www.sciencemag.org)
| evantahler wrote:
| Fusion: let's make a tiny star and hold it in place with magnets.
|
| So dang cool.
| galgalesh wrote:
| The more I read about fusion, the less I think it's anything
| near to a star. The kind of fusion is completely different. A
| sun wouldn't work on earth because it doesn't produce enough
| energy per square meter. It isn't even in de same ballpark. The
| only reason why our sun produces so much energy is because it's
| so incomprehensibly large. A compost heap produces more heat
| per square meter than the sun.
|
| Fusion reactors are incredibly cool. But they're not
| "harnessing the power of a sun".
| drchickensalad wrote:
| That's why fusion is so cool. We're making something that
| runs a higher temperature than the sun's core. It's not even
| strong enough for us! We can't rely on that super slow
| quantum tunneling fusion; we're gonna make stronger yet
| thinner stars at home and literally suspend it in extremely
| limited space.
| ska wrote:
| > "harnessing the power of a sun".
|
| isn't that solar?
| cletus wrote:
| Lots of talk about shrinking the magnets required (which is a big
| part of ITER's cost). Useful of course but the article doesn't
| mention the big problems of neutron embrittlement.
| Robotbeat wrote:
| How many fusion startups have made neutrons? (I know this is a
| low bar... Fusors can do it pretty easily, but I still want to
| know.)
| [deleted]
| CodeGlitch wrote:
| What we need is a SpaceX style company to accelerate development
| of fusion reactors. Elon make it so!
|
| Although perhaps not with so many explosions...
| coolspot wrote:
| How is Lockheed Marting doing with its shipping-container-sized
| fusion reactor?
| pfdietz wrote:
| It grew in volume by a factor of 100, its power density fell to
| about 1/40th that of a fission reactor, and they stopped
| talking about it.
| jacquesm wrote:
| Even so, if they could make it work it would be quite
| amazing. After all, miniaturization is a different challenge
| from getting the thing to work in the first place.
| pfdietz wrote:
| It would be amazing in the same sense a dancing bear is
| amazing. Not because it's useful, but because it can be
| done at all.
|
| Minaturization runs up against limits on power/area through
| the wall (and minimum thickness of T breeding blankets)
| that will force any DT fusion reactor to have power density
| a small fraction of a fission reactor.
| hangonhn wrote:
| The MIT Club of Northern California posted a video a few years
| ago on this exact topic and reactor:
|
| https://www.youtube.com/watch?v=KkpqA8yG9T4
|
| This thing came out of MIT, at least according to the video, and
| was really the collective efforts of a bunch of MIT grad students
| who made the breakthrough partially by taking a very Silicon
| Valley startup approach of using off-the-shelf parts,
| experimenting with new ideas, and starting small. I don't know if
| Professor Whyte framed it that way to appeal to the crowd or not.
| aqme28 wrote:
| I haven't seen that one, but here's another talk on the same
| topic in the context of fusion energy broadly, by some people
| involved https://www.youtube.com/watch?v=L0KuAx1COEk
| elihu wrote:
| Here's a more recent (1 year old) talk that gives a bit of a
| progress update: https://www.youtube.com/watch?v=rY6U4wB-oYM
| Kliment wrote:
| Here is an even more recent (last month) update
| https://www.youtube.com/watch?v=h8uYNhevRtk
|
| tl;dw: SPARC is on track to Q=9, and there will be a magnet
| demonstrator in June, this year
| ohiovr wrote:
| A tokamak can only constrain a plasma in 2 dimensions. To get
| confinement to last longer the magnetic field concentration needs
| to increase. An entirely new way to constrain plasma to 3
| dimensions is needed for practical fusion applications. Otherwise
| accidents will be disastrous for plant operators.
| poopoopeepee wrote:
| > Otherwise accidents will be disastrous for plant operators
|
| What's going to go wrong? I've seen talks that breaches will be
| rapidly cooling and will be contained by a modest amount of
| concrete.
| pfdietz wrote:
| Plasma disruptions
|
| https://www.jp-
| petit.org/NUCLEAIRE/ITER/ITER_fusion_non_cont...
| jtchang wrote:
| These are the kind of advances we need in fusion research. Who
| knows what these new magnets will unlock.
| NortySpock wrote:
| "Commonwealth Fusion Systems announced today that later this year
| it will start to build its first test reactor, dubbed SPARC, in a
| new facility in Devens, Massachusetts, not far from its current
| base in Cambridge. The company says the reactor, which would be
| the first in the world to produce more energy than is needed to
| run the reaction, could fire up as soon as 2025."
|
| The key takeaway, for those skimming.
| Sniffnoy wrote:
| Worth noting, though it's not in the article, that they're
| aiming for a commerical version (ARC) in 2030.
| anotheryou wrote:
| "fire up" != energy positive and ripe for production
| rbanffy wrote:
| I wish this SPARC better luck than the CPUs.
| ape4 wrote:
| Of course, they were from Sun - the sun does fusion.
| jsharf wrote:
| haha this gave me a chuckle. underrated comment.
| reaperducer wrote:
| I wonder if the facility will be called a SPARCstation.
| ksec wrote:
| A _Micro_ _Fusion_ system SPARC which is similarly named to the
| CPU from _Sun_ _Micro-System_.
| mbgerring wrote:
| You mean to say that fusion is only 5 years away? Amazing!
| Florin_Andrei wrote:
| The "only X years away" jokes are predictable, but we'll know
| soon enough if they can do 20 Tesla - and if they can, then
| the time tables should be reset.
| wongarsu wrote:
| "produce more energy than is needed to run the reaction" is a
| great milestone, but "economically competitive method to
| produce electricity" is the real goal and requires a good bit
| of work beyond that
| mrfusion wrote:
| But even without that it could be immensely useful for
| space travel and colonization. And also for remote
| environments.
| maxcan wrote:
| 5 years away and always will be is a 4x improvement over the
| previous 20 years away and always will be!
| api wrote:
| Fusion research has been steadily progressing for many
| years. The "50 years away and always will" quip is baloney.
| dragonwriter wrote:
| > Fusion research has been steadily progressing for many
| years. The "50 years away and always will" quip is
| baloney.
|
| The upthread comment was 20, not 50, and I've heard 15 or
| 20 years away frequently since the 1980s and seen it in
| things dating back to the 1960s, so, no, its not baloney.
|
| Nor does it necessarily mean that progress isn't being
| made, its more of a comment that the unknown unknowns are
| being converted in known unknowns as fast as a known
| unknowns are being converted into known knowns.
| function_seven wrote:
| Just got a new Mac. As I read your comment, my Migration
| Assistant is doing similar estimates. "13 minutes
| remaining" then "41 hours remaining" then back again.
|
| It's been whipsawing between these estimates for the last
| couple hours.
|
| I think I now understand the state of fusion research.
| teachrdan wrote:
| So how far away would you say we are now? Because I
| remember "10 years away" being said in earnest since back
| in the early 90s.
| cygx wrote:
| Depends on the funding. The standard response to the 20
| years away for 50 years quip is https://commons.wikimedia
| .org/wiki/File:U.S._historical_fusi...
| tehjoker wrote:
| Why do you think the funding has been so low?
| willis936 wrote:
| The investment prior to any payoff is significant. Few
| countries, or even groups of countries, have had the
| excess capital and idealistic interest to solve the
| problem.
|
| Raegan gutted virtually every US program and refunding
| has only come back to things that are politically
| relevant. "That giant science machine that might one day
| make lots of heat" isn't high on the "political value"
| list.
| tehjoker wrote:
| There was a lot of juice back in the day for research
| priorities around aviation, nuclear weapons, etc but
| those were all things that were militarily significant.
| cygx wrote:
| Who knows. If I had to make a guess, here are some ideas:
|
| You cannot yet make money with it, so there's no
| capitalist lobby. Success is not certain, and timeframes
| are too long for politicians to score points in the
| election game. It's not as cool as space, and the green
| faction isn't too keen on the whole nuclear thing. So
| far, fears about peak oil turned out to be largely
| unfounded (but do note that we probably did pass the peak
| as far as _conventional_ oil production in concerned).
|
| If I kept at it, I probably could come up with more
| theories...
| runarberg wrote:
| I don't think the green faction disagrees with fusion
| because "nuclear = bad". I think the fact that current
| estimates point to the 2060s as the earliest point in
| time for commercial viability. By that point we will have
| had to have moved on from fossil fuel (or at least gained
| net 0 carbon emission) for at least 10-20 years. So
| nuclear fusion is _not_ a solution to the climate crisis.
|
| In other words the green faction is simply disinterested
| in nuclear fusion, like we are disinterested in the Large
| Hadron Collider, sure its a cool experiment, but nothing
| we should be considering to further our goal of fighting
| our current environmental disasters.
| cygx wrote:
| From personal experience, "nuclear = bad" is a thing.
|
| That said, I agree that as things stand today, fusion
| research is no panacea to climate change. However, note
| that the _United Nations Framework Convention on Climate
| Change_ was ratified in '92, and if we'd decided to go
| all-in on fusion back then, who knows where we'd be at
| today...
| runarberg wrote:
| Just because some people believe blindly that "nuclear =
| bad", that doesn't mean they won't change their opinion
| of fusion once they receive an adequate explanation on
| how fusion is different from fission. I've personally
| never met anybody in the wild that disagrees with fusion
| power because of our current track record with fission
| power. I.e. the believe that "nuclear = bad" does not
| equate to the believe that "fusion = bad".
|
| So honestly I don't believe that there exists people in
| the wild who's opinion is: "No to fusion! Because nuclear
| = bad", and if they do exists, I don't think they are of
| anywhere near size and numbers required to influence
| public funding.
| api wrote:
| I don't know, and I don't think anyone does. It depends
| on lots of things including funding and what other
| unknown unknowns there are on the tech/eng tree.
|
| What I do know is that superconducting magnets have been
| getting cheaper, more powerful, and more compact for
| quite some time and that's one of the limiting factors on
| fusion reactor designs. I also know that there is no
| known physical barrier to net-positive fusion, only
| engineering barriers.
|
| If I had to totally guess I'd say someone will show net-
| positive fusion for a brief period of time before 2030...
| assuming the funding is present. It will not be a fully
| viable power plant yet but a proof of concept. This will
| be followed by a huge bump in funding and a race to
| produce power plants.
|
| ... but that's a guess.
|
| It's like asking "when will there be a human base on
| Mars?" We know it's possible and I think it will happen,
| but I don't know how long it will actually take. We could
| probably have one in 5 years if someone wanted to write a
| blank check.
|
| I would bet that we could have a fusion PoC in 5 years if
| someone wrote a blank check and fully funded many
| different credible efforts.
| simonh wrote:
| I'm pretty confident it will make it over the line into
| viability eventually, but it's a really tough problem and
| it is going to take decades. There's still a lot about
| the engineering required we just don't fully understand,
| and it will take a lot of tests and investigation on a
| lot of different fronts to make meaningful progress. So I
| agree, we're in it for the long haul on this one.
| pfdietz wrote:
| Why are you confident it will be viable? Remember,
| commercial viability means not just that it works, but
| that it's better than any competitor. Why is it that
| fusion will win this competition? It's the nature of most
| technologies to fail in the face of something better.
| runarberg wrote:
| I was reading somewhere that the earliest point for
| commercial viability will be in the 2060s. By which point
| we can assume there have been build a lot of renewable
| energy infrastructure (or else the climate crisis is
| still in full effect; and I can't really think about what
| kind of society will have evolved from that disaster).
| This should bring down the cost of renewables even more
| then today as economics of scales grow exponentially.
| Making the quest for comersial viability of fusion even
| tougher.
|
| I honestly wonder if fusion will ever be commercially
| viable. And if all these experiments will simply lead up
| to us realizing that: "cool, so fusion power is possible
| on Earth. Now what should we do with it?"
|
| But hey. Maybe it will be the energy of the future on
| Antarctica or the Moon or something instead.
| jonas21 wrote:
| > _I would bet that we could have a fusion PoC in 5 years
| if someone wrote a blank check and fully funded many
| different credible efforts._
|
| If that's the case, then why hasn't anyone written that
| check? The potential profit from commercialized fusion
| seems enormous (unlike a mars base), and there doesn't
| seem to be a shortage of capital seeking large returns.
| willis936 wrote:
| Few people have the ability to write the check.
|
| Musk is the only one that even comes to mind, and he's on
| the record saying he won't touch turbulence.
|
| Still, there is hope.
| dividedbyzero wrote:
| I guess it would be a really really big blank check, and
| then you'd still have to get from a PoC to a commercially
| viable plant and convince the public it's not a hydrogen
| bomb and it's quite safe and then you'd have to
| outcompete renewables for decades to get a decent return
| while you miniaturize your device for use anywhere else
| than a stationary plant, and then someone starts making a
| paint with tiny organic solar cells in it and absurdly-
| efficient batteries and while you can still make a
| killing for niche applications, it's a pittance compared
| to your investment. I guess in the end both risks and
| upfront costs are just way too high to do things that
| way.
| Ekaros wrote:
| Fusion is a complicated thing. Even if we reach net
| positive energy generation before 2030. How much longer
| will mature power plant design take? Lets say something
| lasting at least 10 if not 20 years with reasonable
| maintenance(that is not replacing the whole thing every
| other year). Not to forget that nuclear plants can run 60
| years.
|
| And then comes questions of life-cycle energy inputs and
| costs. How long will it be to be net positive on these?
| That is we spend less energy on cooling the coolant for
| superconductors and overall building the thing.
| willis936 wrote:
| There have been tokamak and stellarator fusion power
| plant studies published every few years for the past
| several decades. Answers to all of your questions and
| more are in them.
| wolfi1 wrote:
| fusion is the energy of the future and has been so for the
| last 50 years
| willis936 wrote:
| Just goes to show that something witty is good at
| convincing a ten year old that something false is true.
| temp0826 wrote:
| I think it will happen. I mean, Duke Nukem' Forever
| actually _did_ eventually get released. Anything is
| possible!
| tambourine_man wrote:
| Hopefully not like an asymptotic curve.
| mpalmer wrote:
| 5 minutes away and always will be.
| Iv wrote:
| People love to joke about it but I remember 20 years ago,
| the joke was about it being 40 years away.
| gweinberg wrote:
| Well, 40 years ago it was 30 years away, so for a while
| it must have been going backwards.
| wlesieutre wrote:
| In SimCity 2000 it didn't show up until around 2050. Game
| was from 1993, so that was a 57 year prediction.
| SkyBelow wrote:
| Given we know how long it has been 40 years away, 20
| years away, and now 5 years away, we can estimate how
| long it will be until it is 0 years away. Unless it goes
| down by a power of 2 each time.
| coldpie wrote:
| Zeno's fusion reactor
| asien wrote:
| Technically speaking we already have << fusion >>.
|
| The problem is we don't have << stable fusion >> this one
| will take another 5-6 years.
|
| Then we need << positive yielding fusion >> today fusion has
| negative yield... that's another 5 -10 years at least.
|
| Finally we need <<commercial scale fusion reactor >> like
| France did with their Nuclear Reactor massive investment from
| post war to today in order to make cost and delay acceptable.
|
| That would be 2040 at least for industrial nuclear fusion.
|
| I have no idea what humanity will look like in that
| timeframe.
| garmaine wrote:
| TFA is about stable, positive yield fusion in 5 years.
| agumonkey wrote:
| IF (if) everything goes to plan than 5 years is quite
| fundamental considering the amount of implications about
| safer cheaper energy.
| fchu wrote:
| The key difference here is that it's a venture backed effort,
| which signals something very different from large state-
| financed research efforts like Iter.
|
| Namely, that there is a path to financial viability
| willis936 wrote:
| MIT's product isn't the reactors: it's HTS coil winding.
| That's the proprietary tech they are developing and
| planning to sell.
| jgalt212 wrote:
| VC backed and
|
| > Namely, that there is a path to financial viability
|
| I see what you did there.
| DesiLurker wrote:
| at this rate we might get fusion before James Webb space
| telescope becomes fully functional!
|
| ref: https://xkcd.com/2014/
| NortySpock wrote:
| The test plant is 5 years away, but yeah, net-gain in energy
| is the target.
| pintxo wrote:
| A five time improvement over the previous estimates
| Veedrac wrote:
| ITER is aiming for Q>1 in 2035 IIUC, so 3x.
| Fordec wrote:
| Wasn't ITER supposed to be built by now? DEMO was
| supposed to start in 2033 as the _successor_ to ITER.
| cygx wrote:
| If you try to coordinate design and manufacturing among
| 35 participating states, delays tend to happen.
|
| Perhaps also noteworthy from a historical perspective is
| that the whole thing was proposed by the Soviet Union,
| which doesn't even exist anymore. The US also pulled out
| of the collaboration in '98, necessitating a redesign;
| they rejoined in 2003, but congress periodically tries to
| pull the plug...
| willis936 wrote:
| It depends on which baseline you're referring to and how
| many more times the US would back out of its financial
| commitment after that baseline was made.
| Veedrac wrote:
| ITER, like many oversized government programs where
| funding and structure are almost entirely political, has
| had delays. First plasma (not full power) was originally
| scheduled for 2016, and is now 2025.
| gary_0 wrote:
| See also: The SLS program (the "Senate Launch System").
| the-dude wrote:
| Six.
| kregasaurusrex wrote:
| An important part of the article mentions bringing down the cost
| of high-temperature ReBCO tape conductors, where SPARC itself
| needed more than entire than what existing companies would expect
| to produce in an entire year. Existing technologies using
| superconductors like MRI machines, large transformers/motors, and
| synchronous condensers for power generation have each benefitted
| from bringing down these costs as the use cases mature.
|
| ITER's estimated timeline having a working reactor by 2025 is
| ambitious, but is also supply constrained in that they're
| projecting the need for more Nb-Ti and Nb-Tn exceeding current
| yearly production amounts as well. For reaching the end goal of
| affordable hyperscale energy production, it's promising to see
| demand increase in order for new competitors to invest in related
| research projects.
| fuoqi wrote:
| What about degradation of superconducting materials under high
| neutron flux which will be generated by a "commercial" load? IIRC
| modern superconducting materials rely on relatively fragile meta-
| structures, which can be easily damaged by a sufficiently strong
| radiation. Changing magnets one-two times per year does not sound
| good for economic viability of such reactors.
| elihu wrote:
| I think if I understand correctly, there'll be a fluid (FLiBe)
| between the plasma and the magnet coils that absorbs most of
| the neutrons. The FLiBe heats up and is used to boil water to
| power a steam turbine.
|
| SPARC isn't particularly designed for durability, but for the
| ARC reactor which is meant to be the commercially-useful
| iteration they're looking at having solder joints on the
| superconducting magnet film so the whole top of the reactor can
| be removed so they can pull out the inner lining in one piece
| and replace it. (Apparently they figured out that regular non-
| conducting solder joints don't actually introduce very much
| resistance.) I don't think there's any plan to replace the
| ribbon.
| jacquesm wrote:
| regular non- _super_ conducting solder joints. They conduct,
| just not nearly as good as the material itself at that
| temperature.
|
| Still, interesting that that would not result in enough power
| to boil away the solder.
| anonuser123456 wrote:
| >IIRC modern superconducting materials rely on relatively
| fragile meta-structures
|
| The HTS 'tape' they use is very robust. A lot of the work they
| are doing is qualifying the coils and magnets under various
| scenarios.
| willis936 wrote:
| Neutron flux at the coils is one of the primary things looked
| at in reactor studies. It is a factor in choosing the thickness
| of the lithium blanket and boron coating.
| soperj wrote:
| All the 50 years, 30 years, 20 years away jokes are silly,
| because the time-frame always had the caveat: Given a certain
| level of funding.
|
| Because the funding never came, the time frame was never going to
| work out.
|
| It's like someone asking for a dev estimate, and then coming back
| in that time and asking where it is. If you were assigned to
| something else clearly it didn't get done.
| hindsightbias wrote:
| We've been spending 0.5 to 1B a year on inertial confinement
| alone for decades.
|
| https://www.laserfocusworld.com/lasers-sources/article/14175...
| ChuckMcM wrote:
| I have some hope for this approach, but as the article points out
| making reliable magnets is really the key. When a fusion reactor
| quenches, the plasma will basically eat the reactor through
| "hole" in the field. I keep hoping an effort to manufacture ReBCo
| coils directly will be successful, it would both make them less
| expensive and likely more reliable. However I expect it would
| require something like a 5-axis 3D printer capability.
|
| Lastly, fusion power is one of the possible 'good' future events
| (unlike climate change, or nuclear war) that give me hope for the
| future of the planet.
| Florin_Andrei wrote:
| Controlled fusion seems one of the few awesome future things
| that's unambiguously good.
| technofiend wrote:
| Particularly if there's some way to capture carbon that's
| otherwise impractical due to energy requirements.
| pfdietz wrote:
| Why is is unambiguously good? There's great reason to doubt
| it could be anywhere close to economically competitive. That
| makes its value pretty ambiguous, in my view.
| ChuckMcM wrote:
| I think that an argument can be made that it will _always_
| be economically competitive. That reasoning includes the
| 'fuel cycle' is non-waste producing, the economics of other
| energy sources continues to rise thus creating a wider
| window for economic recovery, the liability associated with
| fusion will always be less than the liability associated
| with fission, and as the carbon externalizations of fossil
| fuel are priced into its production it will become in-
| economic as well.
|
| Well designed fusion power should come in at or below
| hydro-electric power without the environmental impacts or
| risks associated with dams.
| HPsquared wrote:
| Wind and solar have zero fuel cost, but they cost money
| to build. A fusion plant is always going to be a rather
| high-tech, expensive thing.
| pfdietz wrote:
| This is a bad argument. The fuel cycle is a small
| fraction of the cost of fission power. The main cost is
| the cost of building the plant. Fusion reactors will be
| much larger than and much more complex than fission
| reactors, per unit of thermal power output, so they
| should be more expensive. Fission reactors today are
| uncompetitive, even with liability artificially set to a
| small value, so that argument fails too.
| reissbaker wrote:
| The reason nuclear fission is uncompetitive is its high
| operating costs. The cost to build the plant is a sunk
| cost: if the reactor is expected to be reasonably
| profitable to operate, you can fund building it. If the
| reactor is _not_ expected to be reasonably profitable to
| operate... Good luck.
|
| That's what fusion aims to solve. The fuel is plentiful
| and you can easily buy it; the same can't be said of
| uranium. It's also much safer to run than fission, and
| produces vastly less dangerous waste.
|
| Perhaps your argument is that solar and wind are
| sufficient to power humanity's needs, without fission or
| fusion. That's debatable. But _compared to fission_ ,
| fusion is theoretically better on some pretty critical
| metrics -- if we knew how to build a fusion reactor,
| which we don't yet. If you assume solar and wind won't be
| sufficient, fusion seems worth research.
| [deleted]
| pfdietz wrote:
| Making reliable magnets is A key, but it's by no means the only
| one. Fusion faces many grave obstacles even if the magnets were
| totally reliable and cost nothing.
| thewarrior wrote:
| What are some of the others ? I've heard even if everything
| worked the generated neutrons would eventually destroy the
| reactor.
| pfdietz wrote:
| That's one. Another showstopper is that all the energy has
| to be radiated through the wall of the reactor. By limits
| on this areal power density and the square cube law, the
| volumetric power density of fusion reactors will suck.
| Compare ITER (0.05 MW/m^3) or ARC (0.5 MW/m^3) vs. a
| commercial PWR fission reactor primary reactor vessel (20
| MW/m^3). Stronger magnets don't save a reactor from this.
|
| The large size and complexity of a fusion reactor also
| means their reliability is a huge problem. There are many
| parts and joins there, and the machine will be so
| radioactive hands on access will be impossible. A single
| leak of coolant into the vacuum chamber renders a fusion
| reactor inoperable (while a fission reactor can keep
| operating even with multiple fuel rod leaks.)
| HPsquared wrote:
| A good comparison would be, what's the capital cost of a
| hypothetical fusion plant, compared to equivalent
| renewables (e.g. battery-backed solar/wind)
| thewarrior wrote:
| I've heard the sun has a very low power density it's just
| that it's massive. Maybe it's just easier to create a
| star and live in orbit around it
| pfdietz wrote:
| The key point is the Sun is already paid for. :)
| dejv wrote:
| For anyone interested in small fusion reactors there is another
| startup called Tokamak Energy with great Youtube channel:
| https://youtube.com/channel/UCuSlFJbBUIj1zfJLRnGXSow
| pontifier wrote:
| For anyone interested in even smaller reactors, I'm working on
| a device that believe might be able to scale down to the size
| of a button cell battery.
|
| http://www.ddprofusion.com
| dexwiz wrote:
| Modern super conducting magnets are amazing. It's the next
| generation of miniaturization. We could see fusion in the home by
| the end of our lifetimes.
| amluto wrote:
| That would take a different sort of breakthrough. Fission,
| unlike fusion, does not produce actinides or fission products.
| But it does produce neutrons, and neutrons produce activation
| products, and I don't want neutrons or activation products in
| my house in any quantity. And reactor designs using lovely
| materials like FLiBe involve having those materials around. I
| also don't want them in my house.
|
| To be clear, I would be okay with a neighborhood fusion plant
| so long as the safety measures were well designed. There would
| be no risk of massive catastrophe along the lines of a fission
| plant, but I would want the risks of an activation product
| release or a release of non-radioactive but still nasty
| substances to be appropriately mitigated.
| fmihaila wrote:
| > Fission, unlike fusion
|
| Fusion, unlike fission
| elil17 wrote:
| >Fusion in the home
|
| Why would you possibly want to make reactors that small when we
| already have such extensive electric grids?
| dexwiz wrote:
| Honestly I think the grid will change over coming years. The
| cities will remain similar but rural towns and remote homes
| will be switched to local power or limited connectivity. It's
| too expensive to maintain a modern grid. Connecting power
| used to be closely related to phone, but this is less the
| case with cell and satellite service. Also building utilities
| can be amortized in a way that assumes the entire population
| in a region are captured customers. But as individual homes
| start generating power instead of consuming it, those methods
| of paying for the grid no longer make sense.
| teruakohatu wrote:
| I am doubtful that is something I will see in my lifetime,
| but there are loads of reasons why people would want it. For
| a start in New Zealand we pay a lot more to the grid
| operators than I pay to generators for power most of the
| time, the only exceptions being large spikes in power prices
| due to shortages.
| Florin_Andrei wrote:
| All I want is truck-size fusion reactors.
|
| That would open up the Solar System the way the steam engine
| opened up the oceans.
|
| Ideally you'd have a custom design for rocket engines, where
| the reactor is semi-open: you feed in fuel through one end,
| and have the nozzle generating thrust at the other end. Even
| better if you could optionally close that, when you need only
| electricity but no thrust.
| danans wrote:
| Obviously, to power DeLorean time machines
|
| https://backtothefuture.fandom.com/wiki/Mr._Fusion
| justicezyx wrote:
| Because it is cool?
|
| Seriously, having such thing on a car is a god send. And a
| lot of people are looking for live off-grid nowadays; plus US
| power grid does not look like will sustain without a lot of
| capital.
| elihu wrote:
| I'm now imagining an implausible scenario with a SPARC
| reactor loaded onto a trailer and being used to power Jay
| Leno's steam powered car.
| DarmokJalad1701 wrote:
| Spaceflight
| scythe wrote:
| I remember being in high school and visiting the large magnet
| facility in Tallahassee at FSU (you know, where they levitate
| frogs). They explained to us that the superconducting coils were
| made of niobium-titanium alloy, and I remember asking: "aren't
| there better superconductors?". The answer was yes, there are,
| but they're insanely difficult to make or something, so we don't
| consider it practical, "maybe someday".
|
| It looks like "someday" finally got here -- the cuprates are
| being used in practice.
| zafka wrote:
| Are there any startups working on the material science side of
| making these magnets? It seems like a very tight engineering
| team might do well here.
| elihu wrote:
| In one of the SPARC talk videos I think someone asked who
| makes the Rebco film, and the speaker said there were a
| handful of small companies around the world. I don't remember
| if he was any more specific than that, but anyways it seems
| it's kind of a novelty low-volume product at this point. I
| assume with demand picking up that manufacturing capacity is
| going to grow along with it.
|
| Low temperature superconductors in general is, of course, an
| active area of research. There may be better alternatives to
| Rebco just waiting to be discovered.
| pontifier wrote:
| I'm working on a concept that would use the field from a COTS
| permanent magnet MRI machine. I've got more information at
| http://www.ddprofusion.com
| nickik wrote:
| I still don't understand why people want fusion.
|
| Like fisson already does basically what you need and is easier in
| every way.
|
| Yes, the energy density of fusion is higher but the energy
| density of fission is already so absurdly high compared to
| chemical.
|
| There are only a small number of cases where I can think of this
| making sense, and even then it would likely not be worth it.
|
| The problem with nuclear power is the lab to operations process,
| regulation and engineering cost. Fission will likely not improve
| on either of those compared to fission reactors now being
| developed.
|
| If we can't can't get a Molten Salt reactor with a CO2 Brayton
| Cycles turbine into commercial deployment, I have little hope for
| Fusion.
|
| And if we do, then its hard to see how Fusion reactors beats it
| on price.
|
| That said, I want fusion for crazy rocket concepts.
| AnimalMuppet wrote:
| Fusion is much less likely to have accidents that poison the
| local landscape for the next 10,000 years.
| epistasis wrote:
| As odd as this may sound, this is not an impediment to
| current nuclear fission deployment. The risks are small, and
| many populations are very willing to accept them. See France,
| as well as most places in the US that already have nuclear
| reactors nearby. Or for that matter, many many sites in the
| UK.
| Judgmentality wrote:
| I am skeptical of this, assuming you need some sort of
| public support in order to build a nuclear power plant (I'm
| guessing voters are involved somewhere, even if it's
| electing their state governor).
|
| Most people are scared of nuclear power, so it seems
| politically problematic (at least in the United States).
|
| I went to school in Pittsburgh where there are nuclear
| power plants nearby and people still felt more comfortable
| with coal being shipped over from Virginia.
| epistasis wrote:
| Current sites that would welcome new nuclear, as
| evidenced by enthusiastic local support matched by a new
| construction project:
|
| * Vogtle, Georgia
|
| * VC Summer, South Carolina
|
| * a cluster of small towns in the west that are the first
| customers for small modular reactors
|
| * Wylfa, UK
|
| * Hinkley, UK
|
| The greater challenge with nuclear is getting the funding
| to construct, followed by actual engineering,
| procurement, and construction.
| reissbaker wrote:
| The funding problem is because of the safety problem.
| There are high regulatory costs associated with building
| new (fission) nuclear power plants, because:
|
| * If you don't regulate the materials and fuels used for
| fission nuclear power plants, most countries could easily
| build nuclear weapons, and
|
| * If you build fission power plants badly, or maintain
| them poorly, everyone and everything around them dies in
| a large radius, and in an even larger radius gets
| severely sickened. And this radius is poisoned
| effectively forever.
|
| If there weren't safety problems inherent to fission
| nuclear reactors, they would be much cheaper to build as
| well as being much cheaper to operate -- and thus easier
| to fund. That's part of why fusion reactors are
| interesting: theoretically they should work just as well
| if not better than fission reactors at converting fuels
| to energy; the fuel is more prevalent and cheaper; and
| there should be lower costs associated with building and
| operating them since the risks are lower.
|
| We just don't know how to build them yet, and figuring
| that out is expensive.
| pfdietz wrote:
| > The funding problem is because of the safety problem.
|
| I have yet to see convincing evidence of this. It seems
| like an excuse. Perhaps it's code for "the regulators
| won't let us get away with screw ups", which is what
| happened at Flamanville.
| [deleted]
| nickik wrote:
| The chance of that happening with the fission reactors
| currently being built is almost vanishingly small.
|
| And even the largest nuclear accidents ever did not lead to
| anything close to that.
|
| This is just fear mongering nonsense. And btw, even with
| Fusion you still produce huge amounts of high energy
| particles that can be just as dangerous and can be used to do
| bad stuff as well.
|
| Fusion is not magic.
| pfdietz wrote:
| On the other hand, they will almost certainly have tritium
| leaks far larger than from fission plants. A single 1 GW(e)
| DT fusion reactor would burn enough tritium each year to
| contaminate 2 months of flow of the entire Mississippi River
| above the legal limit for drinking water. Leaking even a
| small fraction of that could have serious consequences.
| phreeza wrote:
| The question is why wouldn't you want fusion. More options are
| always better I think.
| pfdietz wrote:
| I wouldn't want it because it would be far too expensive.
| nickik wrote:
| I'm not saying I don't want it. It just seems as humanity we
| totally fucked up. We found a revolutionary new energy source
| and we totally fucked up the deployment of it.
|
| We should live in a nuclear age already, fission powered
| space craft, trains, ships, power stations, remote
| electricity. There is no fundamental reason why fission
| should not be used an all of those.
|
| Yet we almost don't use it at all, and phasing it out at the
| same time as we face climate change.
|
| At the same time huge money is spent on Fusion that is much
| less likely to actually help. With the money spent on ITER
| you could literally run a matcher competitive competition to
| build 3-4 new fission reactors and likely multible new
| powerful turbines.
|
| A molten salt reactor with a brayton turbine would likely be
| far more revolutionary then whatever ITER can ever be.
|
| In general I just feel like fission is disliked and future
| has this 'wow the future could be magical', and I'm saying,
| the present could be magical, we don't need to wait for some
| magical technology. All that is required is some engineering
| and a general acceptance that fission is good among
| politicians, regulators and people.
|
| If some start ups want to work on it, I'm not against it. The
| point is more that even if this magical technology break-
| threw happens, deploying it in the real world will run
| against many of the same problems as fission does.
| orthecreedence wrote:
| The problem, in my view, is mostly regulatory capture and
| this incessant drive to let markets do their thing.
|
| As it stands, fossil fuels should be taxed so high that
| building, maintaining, and running nuclear power plants is
| _cheap_ in comparison. Yet we have continued investment
| into fossil fuels even though we 're now fully aware of the
| damage they're doing. And people say "oh, well we don't
| have nuclear, because it's so expensive." You know what
| else is expensive? Entire cities being under 6ft of ocean
| and having to relocate hundreds of millions of people.
|
| In other words, the _known_ externalities are not imbued in
| the price, because yay capitalism. I think a little market
| tampering is warranted when planetary survival is at stake.
| And obviously, the ramp-up should be gradual, ie, we should
| have been starting this 20 years ago, when it was _also_
| painfully obvious that digging up huge amounts of carbon
| and burning it is a bad idea. Oops.
| fastball wrote:
| - no radioactive waste
|
| - no nuclear meltdowns / runaway processes
|
| - more abundant fuel (on earth and the rest of the solar
| system)
|
| - less pre-processing of fuel
|
| - fuel cannot be used to easily make weapons
|
| Should we use fission right up until we have viable fusion? Of
| course, we should definitely be building more fission reactors.
| But I can't think of a single reason we'd continue using
| fission once we get to fusion.
| hairytrog wrote:
| - there is waste, it's just shorter lived than fission waste
| and lower in quantity. The expectation is that fusion
| reactors will have to be regulated in almost exactly the same
| way as fission reactors because they are nuclear sites, with
| nuclear waste, and proliferation concerns.
|
| - there is lot's of pre processing of the fuel to breed the
| Tritium in a molten salt blanket that surrounds the reactor
| and separating from the salt and then feeding it into the
| chamber
|
| - there is plenty of fission and fusion fuel. Yes, there is
| more hydrogen around.
|
| - tritium is used in nuclear weapons as a booster, to
| dramatically lower the amount of necessary fissile material -
| each fusion reactor is a fast neutron source, which means it
| can be used to make weapons grade materials. Conveniently, it
| has a breeding blanket for tritium, in which other fertile
| fuels can be place to make weapons material: proliferation
| concerns are a real problem for fusion
| willis936 wrote:
| - tritium is used in nuclear weapons as a booster
|
| It is, but tritium is not put into bombs. Lithium is.
|
| - proliferation concerns are a real problem for fusion
|
| Unless all fissile materials are banned. It is very easy to
| check for the existence of fissile materials. If there were
| no legitimate, safe reasons to have any fissile materials
| in use on the planet, then a global ban on fissile
| materials is on the table. A treaty where every nation
| checks on the other is reasonable. It is hard to build a
| secret fusion reactor, just as its hard to build a secret
| uranium centrifuge.
| philipkglass wrote:
| _It is, but tritium is not put into bombs. Lithium is._
|
| Both are put into bombs.
|
| _The main concern when it comes to tritium supply,
| regards tritium used for boosting of fission charges.
| Both applications are crucially important, but fusion
| boosting appears to require significantly larger
| quantities of tritium. Tritium and deuterium for boosting
| are supplied to the weapon from an external reservoir
| (gas bottle) as part of the arming process of the
| weapon._
|
| _Since about 5.5% of existing tritium decays every year,
| the tritium assigned to each weapon must be regularly
| replenished. This is done by removing the weapon's
| tritium reservoir and exchanging it with a newly refilled
| reservoir (5). Figure 1.3 shows what may be such a
| reservoir._
|
| From Norwegian Defence Research Establishment report
| "Tritium production":
|
| https://publications.ffi.no/nb/item/asset/dspace:6780/20-
| 013...
|
| Also see this Savannah River Site page about tritium
| supply for weapons:
|
| https://www.srs.gov/general/programs/dp/index.htm
|
| And for a deeper dive, this fascinating blog post:
|
| "U.S. Tritium Production for the Nuclear Weapons
| Stockpile - Not Like the Old Days of the Cold War"
|
| https://lynceans.org/all-posts/u-s-tritium-production-
| for-th...
| why_Mr_Anderson wrote:
| You are both correct :) Tritium is used for boosting
| fission bombs, lithium (lithium 6/7 deuterides) as fusion
| fuel in thermonuclear bombs.
| benlivengood wrote:
| > more abundant fuel (on earth and the rest of the solar
| system)
|
| This is by far the most important reason in the long term.
| Between stars and even at our own outer planets where solar
| panels aren't reasonable fusion is the only long-term large
| scale energy source.
|
| It's the difference between being stuck as a Kardashev I or
| II civilization or approaching III.
|
| > Should we use fission right up until we have viable fusion?
| Of course, we should definitely be building more fission
| reactors. But I can't think of a single reason we'd continue
| using fission once we get to fusion.
|
| The power density and relative simplicity of fission
| (including mere thermocoupled) is still worthwhile for
| robotic probes or initial sources of power in distant places,
| but we'll be able to make our own fissionables indefinitely
| once we have solid fusion power.
| Robotbeat wrote:
| It is, of course, the regulatory cost they want to attack.
| Fusion can't continue melting down. Unlike fission. The fact
| that it's much harder to get to work at all is considered kind
| of an advantage here because it means the reactor can't
| accidentally keep producing energy when you don't want it to.
| Second, if you get really good at fusion there are some
| reactions that don't produce neutrons means you don't get all
| this activated material. And that lack of neutrons also makes
| it proliferation-resistant (and can allow more compact ways of
| generating electricity than a typical thermal cycle). But even
| with the low hanging fruit type of fusion with tritium &
| deuterium, you don't get these long lived transuranic isotopes.
| Also, fusion has some important very long term applications in
| human spaceflight (& interstellar travel). And the fusion fuel
| infrastructure is much less susceptible to being diverted to
| making weapons.
|
| But overall I agree with you. Fusion makes fission look really
| easy, and there are advanced fission designs and processes
| which address most of the above issues.
| pfdietz wrote:
| If we built a fission reactor with the low power density of a
| fusion reactor it would be so big it couldn't melt down, just
| from its own thermal inertia.
| willis936 wrote:
| Fission has a few unavoidable issues: long radioactive isotope
| half-life, weapons proliferation, and the runaway scenario.
| Fusion has none of these issues plus the fuel being abundant.
| It's the answer to the question "how do we meet the growing
| energy demands of humans over the next thousand years?".
|
| The only real danger is that of a tritium leak, but the short
| half-life makes the prospect of a leak less concerning.
| morning_gelato wrote:
| Why is the runaway scenario unavoidable for nuclear fission?
| Pressurized water reactors for example have negative void and
| temperature coefficients, and from what I've read about
| potential future reactors designs (e.g. high temperature gas
| reactors and some of the molten salt reactors)
| passive/inherent safety is a major selling point.
| willis936 wrote:
| All of those solutions involve better ways at keeping
| neutron multiplication factor below 1. Fission reactors
| need fuel that naturally have an eta above 1. Fission
| reactors are also designed to have large quantities of fuel
| inside of them. So if the control systems fail, even if
| those control systems are built-in chemically, then you
| have a disaster that lasts for timescales that humans would
| prefer not to be on the table.
| morning_gelato wrote:
| What's a scenario where passive safety systems, say those
| of a HTGR with TRISO fuel, fail and cause it to go prompt
| critical? I'm genuinely curious about this, as everything
| I've read suggests this is essentially impossible due to
| the design of the reactor, fuel, and coolant.
| willis936 wrote:
| I don't have an answer. Not knowing failure modes doesn't
| mean they don't exist. HBO's Chernobyl series highlighted
| how dangerous surpressing information about fission
| reactors is. No one knew how the design could fail until
| it did and then it was painfully obvious. I'm not saying
| that HTGRs can meltdown nearly as readily as RBMKs, but
| the risk of the unknown needs to be given respect when
| the stakes are high.
|
| It's difficult to be sure of safety in complicated
| systems when the only people with enough technical
| expertise to fully vet the systems have an interest in
| their success. I'm not saying it can't be done, but I
| think it slows policy down significantly.
| morning_gelato wrote:
| How could someone demonstrate the safety of these systems
| if their very association with those systems is a
| sufficient reason for you to doubt them? If the research
| and experiments of nuclear engineers, scientists, and
| regulators from around the world cannot be trusted to
| develop or assess the safety of fission reactors, why
| does this change with fusion? I also have not seen
| evidence that anyone is attempting to suppress
| information about nuclear safety. Overall nuclear power
| has an outstanding safety record and ranks among the
| lowest deaths per TWh of any energy source (and this
| includes Chernobyl)[1][2].
|
| For the record the HBO series on Chernobyl, while a good
| show, greatly exaggerated parts of the story. There was
| no threat of a megaton-level thermonuclear explosion that
| would destroy Kiev or make huge parts of Europe
| uninhabitable from the melted core coming in contact with
| water. The soviets did know about the RBMK's propensity
| to have a runaway reaction, and the rest of the world
| never allowed those types of reactors to be built.
|
| [1] https://www.statista.com/statistics/494425/death-
| rate-worldw...
|
| [2] https://ourworldindata.org/grapher/death-rates-from-
| energy-p...
| tehjoker wrote:
| Assuming all that is true, reality is extremely
| unpredictable. Imagine a country is at war and they
| accidentally drop bombs on the reactor that crack the
| fuel and change the chemistry enough. A volcano erupts
| under the plant. Imagine a nuclear weapon going off
| nearby and causing a meltdown (for example, if the
| attacker was using a "low yield" neutron bomb). Imagine
| an astronomical phenomenon that happens to pass through
| the plant.
|
| Low probabilities, but man they would suck.
| Ixio wrote:
| We keep finding new ways to make fission safer and reducing
| risk of runaway scenario but I'm pretty sure we'll never
| reach zero risk. Sure we might reach it on paper but human
| error can always happen. Chernobyl operators thought their
| reactor design had zero risk of exploding, current reactors
| are much safer but I'm pretty sure the risk isn't zero.
| morning_gelato wrote:
| With modern reactor designs the inherent safety
| mechanisms mean that humans are not in the loop to reduce
| reactivity or remove decay heat.
|
| Here's an example from Argonne National Laboratory:
|
| > In the first test, with the normal safety systems
| intentionally disabled and the reactor operating at full
| power, Planchon's team cut all electricity to the pumps
| that drive coolant through the core, the heart of the
| reactor where the nuclear chain reaction takes place. In
| the second test, they cut the power to the secondary
| coolant pump, so no heat was removed from the primary
| system.
|
| "In both tests," Planchon says, "the temperature went up
| briefly, then the passive safety mechanisms kicked in,
| and it began to cool naturally. Within ten minutes, the
| temperature had stabilized near normal operating levels,
| and the reactor had shut itself down without intervention
| by human operators or emergency safety systems."
|
| https://www.ne.anl.gov/About/hn/logos-winter02-psr.shtml
| hairytrog wrote:
| Since the reactors would ostensibly be continuously
| operating, the danger is the same. 10+ year half life is
| about as dangerous as 10000 years because you are always
| generating the waste.
| reissbaker wrote:
| Er, no. If you generate the same volume of waste per year,
| but for a fusion reactor the waste stops being a problem
| within a century and for a fission reactor it takes 10,000
| years, at any point in time after the first 100 years,
| waste from a given fusion reactor will be less prevalent
| than waste from a given fission reactor.
|
| It also doesn't matter that no specific nuclear reactor
| will have a lifetime of 10,000 years. The problem is that
| per megawatt of energy generated, fission theoretically
| creates (much) longer-lived waste than fusion. Over a
| longer-than-one-hundred-year timeframe, equivalent amounts
| of energy generation result in vastly different waste
| carrying costs. Fusion's waste carrying costs are much
| lower.
|
| And obviously that number is even more in favor of fusion
| if it only takes 10 years. (ITER claims 100 years though:
| https://www.iter.org/sci/Fusion)
| willis936 wrote:
| The danger is not the same between fusion and fission.
|
| Firstly, 10 years worth of energy is inside a fission
| reactor and is capable of releasing most of that energy in
| an instant if not properly controlled. This cannot happen
| in a fusion reactor. A year's worth of fuel is in a gas
| tank on the wall and needs absurd conditions to ignite. It
| cannot happen spontaneously.
|
| Secondly, the exhaust is helium-4: a stable isotape of a
| valuable element.
|
| Thirdly, the neutron bombardment in a fusion reactor
| activate the materials they hit. If they hit lithium then
| they make tritium: a much needed isotape for fuel in first
| generation fusion reactors. The other materials they hit
| are chosen to have half-lives of less than 100 years. So
| you have a nuclear site that no one's allowed to touch for
| a while then you can recycle the materials. It's nothing
| like the transuranium nuclear waste from fission plants.
| roywiggins wrote:
| If you had a half life of 5 minutes you'd only need to
| store the waste for a couple hours before burying it
| somewhere and there's a certain (smallish) amount of high-
| grade waste at any given moment, no matter how long you run
| the reactor.
|
| 10 years isn't 5 minutes, but it means you just need to
| keep it secure for a few decades before burying and
| forgetting it rather than _many human lifetimes_.
|
| Any leaks will be (to some extent) self-cleaning, insofar
| as they'll decay substantially within a human lifetime, so
| if you stop the leak you can wait a couple decades and it
| will have cleaned itself up. That's much better than the
| long-life stuff fission produces.
| [deleted]
| runarberg wrote:
| I guess people are increasingly frustrated with the failure of
| the current nuclear reactors to cost scale in the modern
| economy, so they look forward for a fundamental shift in
| technology. That is, there is no hope in fission, it has not
| stood the test of time so far, and it there is no reason it
| will in the near future. If we want nuclear we can only hope
| for fusion.
|
| Note that this is me projecting. I don't have a horse in this
| race. I'd be perfectly happy with nuclear free Earth; with
| renewables being our primary method of generating energy; a
| future which as of now looks the most likely. And if people
| develop fusion at some point in the future... cool.
| pfdietz wrote:
| Yes, it's magical thinking born of frustration, not something
| that one should truly expect.
| wcarss wrote:
| I imagine that the popular view of fusion will be better,
| because of the impossibility of meltdown and the much easier to
| manage spent materials. If that translates into less NIMBYism,
| the regulatory costs should be much lower.
|
| If the inputs can then ever be scaled, it could present a
| gateway to powerplant "mass production", which would be truly
| revolutionary. Especially for those crazy rocket concepts!
| pfdietz wrote:
| If a fission reactor had a power density as low as a fusion
| reactor, it would also be impossible to melt down, just
| because the thermal inertia of the core would be so large. Of
| course, it would also be uneconomical, because of the cost of
| that larger core (just as a fusion reactor would be
| uneconomical.)
| clarkmoody wrote:
| Fusion could be a great equalizer in terms of global access to
| large amounts of energy: if you have moderately good access to
| the ocean, you have a nearly inexhaustible source of the
| hydrogen isotopes available in seawater and required as fuel
| for a fusion reactor.
|
| Contrast this with both fossil fuels and fission materials.
| Those resources are the foundation of modern geopolitics.
| Seawater is not, and way more people have access to it.
| krasin wrote:
| re: regulation. This is the problem with fission. but not
| necessarily so with fusion. The reason is that unlike fission,
| where it's impossible to a small company to get a handle on
| fuel and build a fission plant in a less-regulated country,
| with fusion that becomes a lot more approachable.
|
| But I am just as skeptical as you about the future of fusion
| and fission in the US and Europe.
| marcosdumay wrote:
| From my point of view, fusion is incredibly important for long
| term space exploration... but I would agree, not much else.
| Even the "not so long" term space exploration can be done with
| fission.
| Florin_Andrei wrote:
| > _I still don 't understand why people want fusion._
|
| > _That said, I want fusion for crazy rocket concepts._
|
| There you go, you answered it yourself. Fusion rockets would
| open up the Solar System the way the steam engine opened up the
| oceans.
|
| Also on Earth, fusion would be cool. It's less dirty than
| fission, and the fuel is FAR more plentiful.
| reissbaker wrote:
| People want fusion because fission reactors leave long-lived
| radioactive waste, can melt down dangerously, and use the same
| fissile materials as nuclear weapons, making combating nuclear
| proliferation difficult.
|
| That's why there are extremely high regulatory costs associated
| with fission reactors.
|
| (I'm not saying we should _wait_ for fusion reactors, but there
| 's a lot of good reasons to develop them, and once fusion
| reactors are available there's a lot of good reasons to stop
| building fission reactors at that point.)
| pfdietz wrote:
| People want fusion because of mental inertia. Fusion was long
| sold as the future, so the idea that's it's desirable has
| become a social default. But it's a fossil belief, perhaps
| true decades ago, but with little to justify it now.
| dmitrygr wrote:
| The issue is that the current fusion choices (deuterium)
| produce neutrons during fusion, that hit your containment
| vessels, and ... create long-lived radioactive isotopes while
| slowly embrittling the containment vessel. When you replace
| it, it is in fact, a long lived radioactive husk that you
| need to safely contain for a long time. There are other
| fusion options that do not, but they are MUCH harder to fuse
| than deuterium (what we are still trying to achieve)
| reissbaker wrote:
| While true, it's still better than fission in terms of
| waste. (And much less liable to Fukushima-style meltdowns,
| and less likely to lead to nuclear weapon proliferation.)
| dmitrygr wrote:
| Well, actually, a nice source of a large number of
| neutrons is a HUGE proliferation thread: weaponizable
| Pu-239 is produced out of easily-available U-238 by
| neutron capture. Only generation 2 (or 3) fusion, when we
| move past deuterium, will be proliferation-safe.
| reissbaker wrote:
| It's a threat comparable to fission reactors only if
| fusion reactor containment vessels are built out of
| uranium, which they aren't.
|
| To put it another way: operating a nuclear reactor today
| is expensive due to regulatory constraints meant to
| prevent nuclear weapon proliferation. If the fuel for
| your reactor can't be mistaken for nuclear bomb parts,
| and the components of your reactor can't be mistaken for
| nuclear bomb parts, it's a lot cheaper to build and
| operate. And it's a lot safer for someone to sign off on
| "Yep that's a whole bunch of lithium for a fusion
| reactor" than looking at a bunch of uranium and being
| like... Well...
| dmitrygr wrote:
| > operating a nuclear reactor today is expensive due to
| regulatory constraints meant to prevent nuclear weapon
| proliferation
|
| The way I read that, you seem to imply that this cost
| dominates all others. If you do mean that, i'd like to
| see a citation please.
| reissbaker wrote:
| Here you go:
| https://www.americanactionforum.org/research/putting-
| nuclear...
|
| "These figures have profound implications for the
| industry's bottom-line. Based on a review of per-plant
| profitability, there are at least six plants nationwide
| where regulatory burdens exceed profit margins."
|
| Regardless, as I mentioned, the entire process is safer
| from a proliferation perspective.
| pfdietz wrote:
| Those regulatory burdens described there exceed profit
| margins on operations. Those margins ignore the sunk
| capital cost of the plants.
|
| For new nuclear construction, these regulatory costs
| would be a small compared to the cost of actually
| building the plants. Of course, new nuclear plants would
| be outrageously unprofitable.
| reissbaker wrote:
| You can't ignore operating costs because of sunk capital
| costs. That's the sunk cost fallacy! You can sometimes
| ignore sunk costs if operating revenue is good. But if
| it's negative, _that 's the problem._
| [deleted]
| Valgrim wrote:
| There are several advantages:
|
| A fusion reactor doesn't create create long-lived radioactive
| waste (or any kind of pollution).
|
| A fusion reactor cannot be used to create nuclear weapons.
|
| A fusion reactor doesn't require any form of mining for it's
| fuel.
|
| A fusion reactor cannot meltdown in any way.
|
| Due to these inherent safety features, the costs associated
| with the regulation and engineering a fusion power plant could
| be much lower than a fission plant.
| gizmondo wrote:
| It will be easy to use neutrons from DT fusion to get weapon-
| grade plutonium. This may be easier to police, i.e. "there
| should be no uranium nowhere near a fusion plant", but that's
| a much subtler statement.
|
| And of course mining for lithium as a fuel is still
| necessary, so you should perhaps say "no additional mining"
| or something.
| rnhmjoj wrote:
| > And of course mining for lithium as a fuel is still
| necessary, so you should perhaps say "no additional mining"
| or something.
|
| True, but the quantity of lithium required to breed tritium
| for power generation is ridiculously low. Operating a DEMO-
| like reactor for 30 years would consume 2 tons of lithium,
| which is nothing compared to the annual consumption for
| battery manufacturing (around 30000 tons).
| pfdietz wrote:
| And enriching lithium is necessary. A single ARC reactor
| would use a good fraction of all the 6Li produced for the
| US thermonuclear weapons program.
|
| The tritium produced in a fusion reactor program would make
| it much easier to engineer high yield fission bombs, via
| boosting.
| willis936 wrote:
| The need for lithium is a valid point. The amount required
| for fuel is very small though. A 1 GW plant would use more
| on initial filling than a 30 year lifetime of refilling and
| even that first filling would be on the order of a metric
| ton (unverified ballpark, dependent on reactor size,
| blanket thickness, and plumbing overhead). 80,000 metric
| tons of lithium are mined each year. We consume about 18
| TW.
|
| So I estimate that converting all electricity sources to
| fusion would use about 1/4 of a year's worth of lithium,
| but would be enough to make 30 year plants, which would
| still have most of their lithium left over for
| recycling/reuse afterwards.
| andy_ppp wrote:
| So their main advancement is stronger magnets with "rare-earth
| barium copper oxide (ReBCO) on metal tape" being wound into
| extremely tight loops (and is presumably extremely thin).
|
| Will we enter into a tipping point of materials science that
| allows magnets strong enough and suddenly we get fusion and it
| becomes ever better as we make better superconducting magnets?
| mysterEFrank wrote:
| the magnet singularity is coming
| DennisP wrote:
| That's pretty much what's happening here, fusion output
| increases with the fourth power of the magnetic field. Double
| the field, 16X the output. But if we take it much further,
| we'll reach a point where the limit is the structural strength
| of the reactor.
|
| A few years ago I got to tour MIT's Alcator C-Mod, which had
| the most powerful field of any tokamak to date. A grad student
| showed us a metal tie rod, about a meter long, and said they'd
| calculated that two of them could hold down the Space Shuttle
| while it was trying to launch. To hold the reactor together
| while it was operating took 38 of those.
| harveywi wrote:
| Quite possibly. The magnet as a key tool for harnessing the
| immense power of nuclear reactions is only just now coming to
| light, most recently when Dr. Indiana Jones survived a nuclear
| blast by hiding in a fridge covered by a variety of small
| magnets.
| elihu wrote:
| > Will we enter into a tipping point of materials science that
| allows magnets strong enough and suddenly we get fusion and it
| becomes ever better as we make better superconducting magnets?
|
| I think that's the idea. Iter is about as small as it could
| possibly be and still work given the magnet field strength they
| had designed around. With stronger magnets, we can make smaller
| reactors, which are cheaper to make and (if I understand
| correctly) have better power density. At some point it stops
| being practical to make it any smaller as the limits become
| "how thin can we make this shielding material?" or "how much
| heat energy can we remove by pumping fluids around?" And then
| once we've proven the concept and we've settled into an optimal
| size the engineering focus turns to "how cheaply can we
| manufacture this?" and "how can we reduce the total operating
| cost per megawatt hour?".
| tobylane wrote:
| Iter and other big or old projects are going the safe route
| with magnets that need to be at 4 or so Kelvin. All these
| 'hotter' superconductors are relatively unproven (it's a
| oversimplification for a broad category), especially their
| strength when made into the shapes that make the magnetic field
| and form part of the load bearing structure of the container.
| The winners would enter that tipping point.
| Florin_Andrei wrote:
| The sandwich structure described in the article makes sense:
| separate the superconducting and the load-bearing functions
| into different layers.
| cma wrote:
| It is worth pointing out that Iter started in 1985, I think
| before REBCO was discovered (and it was a little bit after
| that they acheived superconductivity at 77K, liquid nitrogen
| temp). Sturdy and flexible tape form from ion beam-assisted
| deposition I think was later but I can't find the date.
|
| (edit: maybe in the lab in 1992? I'm not sure when it scaled
| production: https://en.wikipedia.org/wiki/Superconducting_wir
| e#cite_note... )
| fabian2k wrote:
| Practical use of the new high-temperature superconductors
| in high field magnets is even more recent. NMR is probably
| the closest commercial application for this kind of magnet,
| and the first spectrometers using the new superconductors
| were sold last year.
| NortySpock wrote:
| Fusion seems like it will advance the fastest through (a)
| materials science unlocking better magnets and (b) simulation
| and physical experimentation with reactor designs, including
| highly experimental designs.
|
| Computational modeling seems to be helping as well:
|
| https://ai.googleblog.com/2017/07/so-there-i-was-firing-mega...
|
| Disclaimer: I am not a plasma physicist.
| fabian2k wrote:
| I'm not sure how much potential improvement you can expect
| there in the near future. There's a pretty large jump between
| the conventional superconductors and the new high-temperature
| superconductors used here, I'd suspect that it'll take a long
| time of incremental improvement to build stronger magnets with
| these new materials.
|
| There's a lot of practical problems with building very high-
| field superconducting magnets. I'm also not sure how much you
| can gain from the thinnness of the material, conventional
| superconducting magnets have a lot of non-superconducting
| material in there as well to conduct heat so that the magnet
| isn't immediately destroyed on a quench.
| Valgrim wrote:
| "Suddenly", no. They're targeting 2025 for the first tests if
| everything goes perfectly, 2027 for a first demo reactor, and
| we don't know how expensive a real reactor would be so we have
| no idea if this is the design that will one day unlock
| UNLIMITED POWER!
|
| but on the scale of civilizations, yeah this could be it.
| UncleOxidant wrote:
| 4 years in the fusion field is pretty "suddenly".
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