[HN Gopher] Nuclear fusion has encountered a shortage of tritium
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Nuclear fusion has encountered a shortage of tritium
Author : smusamashah
Score : 56 points
Date : 2022-05-20 20:04 UTC (2 hours ago)
(HTM) web link (www.wired.co.uk)
(TXT) w3m dump (www.wired.co.uk)
| jmyeet wrote:
| ITAR should be shut down. Straight up. It's a complete waste of
| taxpayer funds taht holds no prospect of producing commercially
| viable power. Its design constraints were decided decades ago.
| Since then science and engineering has advanced a lot.
|
| I'd love if it fusion became commercially viable but I'm doubtful
| it ever will. At the least the kind involving fusion atoms in a
| plasma for all the documented reasons, most notably plasma
| turbulence and the power loss and container damage from neutron
| escapes.
|
| I'm not that concerned about a shortage of tritium. That's a
| solvable problem. In fact we probably need a variety of breeder
| reactors for things like this and producing plutonium for deep
| space probes anyway.
|
| Fusion is a trap for many because it seems so easy. I mean the
| Sun is doing a lot of it. But the Sun is relatively inefficient
| (which is compensated for by mass) and it solves the containment
| problem with gravity.
| madengr wrote:
| Stevvo wrote:
| One of the main objectives of ITER is to test Tritium Breeding
| technologies for DEMO. There is no shortage due to heavy water
| plants shutting down because it was never planes to use Tritium
| from that source in the first place!
| jszymborski wrote:
| I'm not sure about the scale here, but is it really as crazy as
| the article says to use tritium that is formed from fission?
| What's the ratio of fusion:fission energy you'd need? I can't
| imagine even if it was 50% or 25% that it wouldn't be worth doing
| seeing as you'd just be fuelling a clean energy source from the
| waste stream of another energy source that doesn't produce CO2.
| marcosdumay wrote:
| The reaction is supposed to be self-sustaining. The reactor
| walls are supposed to emit more than enough tritium to satisfy
| your needs.
|
| Whatever you bring from outside is just to bootstrap it once
| you turn it on. (I imagine they are not collecting the tritium
| between runs, but it's something you are expected to do.)
| ASalazarMX wrote:
| > The reactor walls are supposed to emit more than enough
| tritium to satisfy your needs.
|
| Didn't know that fusion generators produced its own fuel! If
| it produces more than enough, then the excess tritium is
| considered radioactive waste?
| fallingknife wrote:
| Not really an issue though, as tritium has a half life of
| 12 years, and the amounts produced would be negligible
| anyway. You could probably release it into the atmosphere
| harmlessly (not that regulations would ever allow that,
| though).
| adrian_b wrote:
| The kinds of fusion generators that are considered for the
| near future produce most of their energy as kinetic energy
| of neutrons.
|
| The energy of the neutrons is transformed into heat by
| adsorbing them into some shielding walls. The materials for
| those walls will be chosen to minimize the quantity of
| radioactive waste that is produced by the extremely intense
| neutron irradiation, but it is impossible to avoid
| completely the production of radioactive waste.
|
| So all the fusion generators planned for the near future
| will generate radioactive waste, but in significantly less
| quantities than fission reactors of the same power.
|
| Because they produce an intense neutron flux, like the
| fission reactors, the fusion reactors can also be used for
| element transmutation by neutron capture, e.g. for
| producing tritium or for producing lightly-doped silicon
| crystals for the high-voltage electronic devices (by
| transmuting silicon into phosphorus).
|
| However, such transmutation applications usually also need
| the use of a neutron moderator, to slow the neutrons down
| to whatever speed is optimal for producing the desired
| isotope, e.g. tritium. For tritium, heavy water can play
| both roles, of the neutron moderator and of the target
| containing the element to be transmuted.
| jszymborski wrote:
| Wait, so then at _whatever_ cost, the cost of producing
| Tritium is sorta moot, right? Whether it's building reactors
| or investing a tonne of energy, the cost of creating the
| amount of tritium needed is met with theoretically infinite
| profits?
| marcosdumay wrote:
| Yes, in theory. On practice the problem is that the ITER
| doesn't recover enough tritium for economical reasons, and
| thus needs a constant supply of it for running its
| experiments.
|
| There is another, unrelated issue that if we decide to
| scale (H + D) fusion power, for decades we will need more
| tritium than they can generate.
| dhosek wrote:
| >in, ... 12.3 years..., half of the tritium available today will
| have decayed into helium-3.
|
| When I saw this, I thought that sounded odd, shouldn't the atomic
| number go _down_ with radioactive decay? but it turns out that in
| this case what happens is one of the neutrons splits into a
| proton, an electron and an electron neutrino so the atomic number
| goes _up_ by one (unlike the more familiar fission reactions of
| the heavier elements where the atomic number decreases). So much
| physics I've either forgotten or never learned.
| adrian_b wrote:
| This is the standard beta radioactive decay, which increases Z
| by 1, while the alpha radioactive decay decreases Z by 2 (and
| gamma decay does not change Z).
|
| For every A (the number of nucleons in a nucleus) there is a
| ratio between (A-Z) and Z (i.e. between the number of neutrons
| and the number of protons) for which the mass of the nucleus is
| minimum.
|
| Any other isobaric nuclei have an excess of mass over the
| nucleus with the optimal neutron/proton ratio, so they will
| decay towards it. The nuclei with too many protons will capture
| electrons or emit positrons, while the nuclei with too many
| neutrons will emit electrons, increasing the number of protons
| with each emitted electron, until the optimal neutron/proton
| ratio.
|
| For the decay products of uranium and thorium, there are always
| too many neutrons, so the normal beta decay is what always
| happens.
|
| It is possible to artificially produce nuclei with too many
| protons, and there are a few such unstable isotopes that are
| produced naturally, which decay by the reverse beta decay
| (electron capture or positron emission), where Z decreases by 1
| for every captured electron / emitted positron.
|
| For A = 3, the nucleus with minimal mass is helium-3. Tritium
| has too many neutrons in comparison with helium-3, and it must
| get rid of them by emitting an electron.
| db48x wrote:
| Yea, beta decay is weird. On the other hand, transmutation of
| the elements!
| rob_c wrote:
| "tritium for its experiments".
|
| The whole point is to reach a Deuterium or Hydrogen reactor with
| a light lithium ignition in a lot of cases which would be easier
| to fuel than Tritium due do problems extracting it.
| howenterprisey wrote:
| If anyone was wondering if SPARC and ARC care about this, SPARC
| onsite tritium inventory is planned to be fairly low: just 10
| grams (not kg) in this 2018 SPARC paper[0]. I would also
| speculate that 200 kg/year sounds a little bit too high, although
| I can't find an ARC paper to corroborate (the magic words you
| want are "total on-site tritium inventory").
|
| [0]
| https://www1.psfc.mit.edu/research/alcator/pubs/APS/APS2018/...
| [deleted]
| [deleted]
| api wrote:
| Can't an operational fusion reactor breed tritium? If so we just
| need enough tritium to start one.
| ceejayoz wrote:
| The article covers that.
|
| > Tritium breeding was originally going to be tested as part of
| ITER, but as costs ballooned from an initial $6 billion to more
| than $25 billion it was quietly dropped. Willms' job at ITER is
| to manage smaller-scale tests. Instead of a full blanket of
| lithium surrounding the fusion reaction, ITER will use
| suitcase-sized samples of differently presented lithium
| inserted into "ports" around the tokamak: ceramic pebble beds,
| liquid lithium, lead lithium.
|
| > Even Willms admits that this technology is a long way from
| being ready to use, however, and a full-scale test of tritium
| breeding will have to wait until the next generation of
| reactors, which some argue might be too late. "After 2035 we
| have to construct a new machine that will take another 20 or 30
| years for testing a crucial task like how to produce the
| tritium, so how are we going to block and stop global warming
| with fusion reactors if we will not be ready until the end of
| this century?" says Mazzucato.
| BurningFrog wrote:
| I'm very unimpressed by the "we must only consider short term
| solutions to global warming" idea.
|
| We don't know the future, and we keep being surprised by it!
| adgjlsfhk1 wrote:
| if we want to significantly curb global warming, long term
| solutions aren't where we need to focus effort
| DennisP wrote:
| Then it's a good thing we're not focusing effort on long-
| term solutions. We're spending a lot more money on
| rolling out renewables than we are on fusion research.
| That doesn't mean we should cut out long-term solutions
| entirely.
|
| If we want to fund more renewables than we are now, then
| the place to cut back is the many fossil fuel projects
| that we're still investing in. Until we've done that, I
| think any positive effort deserves applause instead of
| complaints about focus.
| api wrote:
| Oops missed that.
|
| ITER is not necessarily the best approach to fusion, although
| it's the best funded.
|
| In any case if we can't breed tritium than we either need to
| shoot for higher energy D-D fusion or some other reaction or
| fusion will never be cost-competitive.
| GuB-42 wrote:
| Is there any other approach to fusion than ITER?
|
| I mean fusion capable of practical power generation.
|
| D-T fusion is the easiest, and yet super hard. Tokamaks are
| the only design that we know how to build in order to meet
| the goal, with maybe stellerators in second position.
| Inertial fusion work for scientific and military
| experiments, but are far from being a usable power source.
| Things like fusors and its derivative are great hobby
| projects with a few limited practical applications, but we
| are not even sure if it is physically possible to produce
| more energy than we put in. As for LENR (aka. cold fusion)
| we are essentially at the "thought experiment" stage, when
| it is not a scam.
|
| One other idea that may work with current tech is to dig a
| large cave, line it with really thick material and detonate
| hydrogen bombs inside it, extracting energy from the heat
| of the explosion. I don't think I need to tell you that
| even if we can do that (unsure), we certainly shouldn't
| (absolutely sure).
|
| Or, take, advantage of that really big fusion reactor we
| already have and makes us go around in circles.
| DennisP wrote:
| Most conservatively, there are tokamaks that use more
| modern superconductors, able to support much stronger
| magnetic fields. Tokamak output scales with the fourth
| power of the magnetic field, so that allows the same
| output as ITER from a much smaller, cheaper reactor. The
| MIT spinoff CFS is doing this, along with Tokamak Energy
| in the UK. CFS is shooting for a net power attempt in
| 2025.
|
| There are also various alternative designs, like Zap
| Energy's z-pinch, General Fusion's magnetized target
| fusion, and Helion's field-reversed configuration. Helion
| is attempting hybrid D-D/D-He3 fusion, the other two are
| D-T.
| cpuguy83 wrote:
| $25 billion... thinking about how much money we've dedicated
| for active warfare in the last 2 months alone... clearly we
| have our priorities.
| gwright wrote:
| I struggle to understand this type of comment.
|
| You can't respond to the bad guys with a plea for them to
| stop what they are doing because you would rather spend the
| money on something else.
|
| That isn't to say that battles should not be picked
| carefully, just that sometimes you don't have a choice and
| have to deal with a situation and spend lots of $$$ and
| sometimes blood in order to avoid a worse situation. Even
| in the context of "last 2 months alone" it isn't clear what
| specific action is being referenced so the comment is just
| too abstract, IMHO.
|
| In some cases it makes sense to engage, in others it
| doesn't. There is no single correct answer unless you want
| to enter into a discussion of pacifism.
| robonerd wrote:
| $25 billion is about 9 Virginia-class submarines. The US
| has already built 22 and plans to build 66. Granted,
| they're very nice and important submarines, but it still
| makes $25 billion seem like chump change by national
| project standards.
| somenewaccount1 wrote:
| Title is extremely misleading.
|
| > "Right now, the tritium used in fusion experiments like ITER,
| and the smaller JET tokamak in the UK, comes from a very specific
| type of nuclear fission reactor called a heavy-water moderated
| reactor."
|
| You litterally just need to make more of these heavy-water
| moderated reactors, which are rare and approaching end of life,
| but certainly you can build more of them if it was the difference
| between having endless energy or not.
| dang wrote:
| Ok, we've changed the title to the subtitle above.
| seniorsassycat wrote:
| > There are other ways of creating tritium but these techniques
| are too expensive to be used for the quantities required, and
| they will likely remain the reserve of nuclear weapons programs
|
| Too expensive for clean power, just right to threaten the world
| [deleted]
| theptip wrote:
| > "It would be an absurdity to use dirty fission reactors to fuel
| 'clean' fusion reactors,"
|
| This seems like a non-sequitur. If we need to keep around (or
| even build) a few heavy-water fission plants to enable the fusion
| industry, what's the problem? The simple phrasing of fission as
| "dirty" really shows the quotee's biases. You could easily
| envision a stable energy mix with a few percent of fission, the
| rest fusion and storage/peaking power, and that would be far, far
| cleaner than our current GHG/pollutant-heavy mix of fossil fuels.
|
| It seems quite premature to call this a "crisis" since we already
| have proven ways of manufacturing the required ingredient. I
| suppose the risk is just that this pushes up the price of fusion
| in the initial phases of deployment, providing an "activation
| cost" that delays fusion from taking over, but that's quite a
| speculative concern at this point.
| perihelions wrote:
| - _" a few heavy-water fission plants"_
|
| It's actually tilted very far in the opposite direction. The
| ratio is something like 600:1 heavy-water fission to fusion. A
| mix of 99.8% fission and 0.2% fusion, if your fusion is relying
| on that as its sole source of tritium.
|
| - _" Small quantities of tritium are also produced by CANDU-
| type nuclear reactors--on the order of 100 grams per year for a
| 600 MW reactor,"_
|
| https://www.iter.org/mag/8/56
|
| You'd need 60 kg/year for a 600 MW D+T fusion reactor.
| theptip wrote:
| Fair enough, perhaps I was oversimplifying with my example.
| It seems from the OP the plan is to transition to breeding
| the tritium in fusion reactors, and that we currently have
| enough fission-produced tritium to plausibly bridge to those
| fusion-based processes. And the concern is that the fission
| reactors might shut down before we bootstrap the fusion
| reactors.
|
| Still, as I said originally, it sounds like keeping our
| current level of fission reactors around should solve the
| bootstrapping problem.
| robonerd wrote:
| > _The simple phrasing of fission as "dirty" really shows the
| quotee's biases._
|
| And I think their failure to really understand fusion power
| either. The sort of fusion reactors we build first will produce
| tons of neutron radiation, which over time will turn the whole
| reactor itself into radioactive nuclear waste.
| 99_00 wrote:
| There's a lot of bad thinking in that one sentence.
|
| All or nothing. We must have completely clean power or it has
| no value.
|
| Not using comparison. How does it compare to other sources of
| energy, (including solar which is built in facilities using
| coal power).
| zitterbewegung wrote:
| Fission is much cleaner than coal power plants in the Nuclear
| isotopes that are released into the air and we can contain
| nuclear waste pretty well.
| JimTheMan wrote:
| At some point, we will have enough solar/hydro/wind etc that
| they won't be built using coal power... Right now it's a
| necessary yes, in the future no.
|
| In a way, that last (...) is also a very black and white way
| of viewing things.
| 99_00 wrote:
| >In a way
|
| In what way is it black and white view of things?
|
| Solar energy production is not 100% clean. It never will be
| regardless if coal is used or not. That doesn't mean it's
| bad. The goal isn't purely clean energy. The goal is
| improved sources of energy.
|
| Hopefully coal isn't used in the future. But things don't
| appear to be on track.
|
| https://www.carbonbrief.org/china-
| briefing-17-march-2022-bei...
|
| Unfortunately, because black and white thinking and
| evaluating energy sources without comparing them has
| resulted in a shortage of natural gas (thanks to fossil
| fuel divestment and ESG) and energy producers falling back
| to coal. The worst possible source of energy.
| c7DJTLrn wrote:
| It's just shit popsci journalism. Better off reading The
| Register.
| westcort wrote:
| My key takeaways:
|
| * In a perfect world, there would be a more ambitious program
| developing the breeding technology in parallel to ITER, Willms
| says, so that by the time ITER has perfected the fusion reactor
| there's still a fuel source to run it
|
| * Like many of the most prominent experimental nuclear fusion
| reactors, ITER relies on a steady supply of both deuterium and
| tritium for its experiments
|
| * When it's finally fully switched on in 2035, the International
| Thermonuclear Experimental Reactor will be the largest device of
| its kind ever built, and the flag-bearer for nuclear fusion
|
| * And as ITER drags on, years behind schedule and billions over
| budget, our best sources of tritium to fuel it and other
| experimental fusion reactors are slowly disappearing
|
| * Right now, the tritium used in fusion experiments like ITER,
| and the smaller JET tokamak in the UK, comes from a very specific
| type of nuclear fission reactor called a heavy-water moderated
| reactor
|
| * "We're hitting the peak of this tritium window roughly now."
| Scientists have known about this potential stumbling block for
| decades, and they developed a neat way around it: a plan to use
| nuclear fusion reactors to "breed" tritium, so that they end up
| replenishing their own fuel at the same time as they burn it
|
| * "Calculations suggest that a suitably designed breeding blanket
| would be capable of providing enough tritium for the power plant
| to be self-sufficient in fuel, with a little extra to start up
| new power plants," says Stuart White, a spokesperson for the UK
| Atomic Energy Authority, which hosts the JET fusion project
|
| * "It would be an absurdity to use dirty fission reactors to fuel
| 'clean' fusion reactors," says Ernesto Mazzucato, a retired
| physicist who has been an outspoken critic of ITER, and nuclear
| fusion more generally, despite spending much of his working life
| studying tokamaks
|
| * "After 2035 we have to construct a new machine that will take
| another 20 or 30 years for testing a crucial task like how to
| produce the tritium, so how are we going to block and stop global
| warming with fusion reactors if we will not be ready until the
| end of this century?" says Mazzucato
|
| Arthur Turrell's book, The Star Builders, is an excellent
| overview of the state of the art of nuclear fusion technology.
| Unfortunately, however, fusion is unlikely to be radically
| cheaper than other sources.
| gitfan86 wrote:
| Last week Elon explained that the problem of fusion is that it
| will be more expensive than solar and wind.
| DennisP wrote:
| The real question is whether it's more expensive than
| solar/wind plus the batteries required for dispatchable
| power.
|
| The answer depends on the reactor design, which Elon doesn't
| know. There are a lot of possibilities, and if the first ones
| are too expensive, later ones might not be.
| Victerius wrote:
| "Precious tritium is what makes this project go. There's only 25
| pounds of it on the whole planet."
| ceejayoz wrote:
| > There's only 25 pounds of it on the whole planet.
|
| "Because we haven't needed more until now, and it's mostly man-
| made."
|
| There wasn't any plutonium on Earth, either, until we decided
| we needed some.
| adrian_b wrote:
| Actually, when the Earth was formed, it contained a non-
| negligible quantity of plutonium (supernovae produce all the
| elements until Z=100, much over the Z=94 of plutonium, but
| the heavier elements had already decayed before the
| interstellar dust reached the nascent Solar System).
|
| Because the longest-lived isotope of plutonium has a half-
| life close to 100 million years, so some 45 halvings have
| happened since the Earth formation, almost all primordial
| plutonium has decayed by now.
|
| A few atoms of the primordial plutonium are still around us,
| though they are much too few to be easily detectable (there
| have been claims that some very sensitive experiments have
| detected them).
| rmdashrfstar wrote:
| What about in near earth asteroids?
| dodobirdlord wrote:
| Tritium has a half-life of about 12 years, meaning that it
| essentially doesn't exist naturally. It's all man made.
| [deleted]
| Goronmon wrote:
| Just to provide the other half of the concern around how little
| there is.
|
| _...it's estimated that working fusion reactors will need up
| to 200 kg of it a year_
| AustinDev wrote:
| The working fusion reactors will produce enough to not need
| additional tritium, it is a self-sustaining reaction after
| all.
| photochemsyn wrote:
| Tell that to the Sun. We already have a fusion reactor sufficient
| to meet all of humanity's energy needs, it's a gravitationally
| contained fusion reactor with a projected lifetime of at least
| one billion years, so why not just rely on that? Seems to have
| done wonders for the biosphere for the last one billion years,
| hasn't it?
| h2odragon wrote:
| Known to cause cancer, tho. And may be implicated in global
| warming.
| nh23423fefe wrote:
| Instead of asking oblique rhetorical questions, you could
| actually make a meaningful statement.
| gfodor wrote:
| It seems like every fusion post is bound to have at least one
| commenter point out that the sun is a working fusion reactor,
| as if literally anyone in these threads will learn something
| from this observation.
| toomuchtodo wrote:
| Roughly $50 billion has been spent globally on fusion
| research since the 1950s with nothing material to show for
| the effort; at what point do you stop throwing good money
| after bad? This strikes me as the learning from these
| posts.
| tedd4u wrote:
| I think you make an excellent point that fusion research
| is underfunded. NASA budget since the 50s is ~$1,400
| billion -- almost 30x what's been put into fusion
| research. We're asking fusion research to produce "free,
| clean, and carbon-free base-load electricity forever."
| Seems worth a NASA-level of investment to me.
| fallingknife wrote:
| Intel has a capex budget of $27 billion just for 2022, so
| you don't really understand scale or have a point.
| toomuchtodo wrote:
| Intel has working products, customers, shareholders, and
| fundamentally, accountability for that research spend.
| Results driven research funding is not unreasonable,
| unless you want to classify this research in the same
| vein as particle accelerators and a curiosity with no
| expectation of success (which is fine; just don't sell as
| an energy silver bullet where there's no evidence it can
| be delivered on). Hope is not a strategy nor a cost
| justification.
| [deleted]
| dariusj18 wrote:
| I'm sure it is difficult to decide that since, as pointed
| out, there is a working example staring at us every day.
| So it always feel just out of reach.
| otikik wrote:
| The Sun doesn't shine for half of the day in most places on
| Earth. Or when there's clouds.
| DennisP wrote:
| The sun is a great fusion reactor, it's just too bad the
| transmission lines go down for so many hours every day.
| toomuchtodo wrote:
| You are spot on. The world will be powered by renewables before
| fusion ever sees its first commercial watt produced.
|
| https://news.ycombinator.com/item?id=31428469
|
| https://pv-magazine-usa.com/2022/05/16/a-fate-realized-1-tw-...
| [deleted]
| adrian_b wrote:
| Moreover, if we would really ever become able to produce by
| nuclear fusion a quantity of energy comparable with the energy
| received from the Sun, then that would cause by itself a great
| climate warming, so nuclear fusion is not a solution against
| it.
|
| If the quantity of energy produced by nuclear fusion would
| remain negligible in comparison with the solar energy, then
| there is no need for it.
|
| While on Earth using the nuclear fusion makes little sense,
| mastering it could enable the exploration and even the
| colonization of the Solar System.
| areoform wrote:
| Just a quick reminder, we already have practical fusion with tens
| of thousands of years of runway available to us today. We choose
| not to do it because it sounds dangerous and it's not politically
| expedient.
|
| For those unfamiliar, I am talking about Project PACER. The
| fusion reactor proposed by Teller after the creation of the
| thermonuclear weapon. It may sound fanciful but it's based on a
| simple precept. We can already induce fusion reactions, albeit in
| an unstable and explosive fashion. What if we took that warhead,
| surrounded it with a giant underground chamber made out of steel
| several feet thick, and let it explode while molten fluoride
| captured the heat?
|
| Their work conclusively shows that this can be done, and that
| molten fluoride salts could capture most of the neutrons to
| prevent embrittlement. A single such facility could power the
| entire country. Oh and it could be configured to create Tritium
| in the process.
|
| https://en.wikipedia.org/wiki/Project_PACER
|
| The project was terminated because it was "bound to be
| controversial" and would "arouse considerable negative
| responses."
|
| The math is sound. The concepts are sound. We could solve the
| _comparatively_ minor engineering challenges and build one today
| while waiting on the the breakthrough needed for controlled,
| continuous fusion.
| WheatM wrote:
| jandrese wrote:
| Some of the heartburn about PACER is that there are failure
| modes that can only be described as catastrophic.
| cogman10 wrote:
| No shit.
|
| Turns out a daily detonation of a fusion bomb tends to wear
| on things and when those things fail... you've just detonated
| a fusion bomb.
| areoform wrote:
| We're facing a catastrophe. I and others have described
| elsewhere that the path we're on is much, much worse than
| even the most dire of predictions the IPCC makes.
| https://news.ycombinator.com/item?id=30947756
|
| Teller et al anticipated your objection. It's why the
| reactor is supposed to dig into sold rock. If there's a
| catastrophic failure then it's yet another subsurface
| nuclear test. And the more advanced designs considered for
| Project Plowshare produce minimal residual radioactivity.
| All of the products dissipate within 6 months.
|
| So, in the worst case scenario, the facility gets buried
| under tons of rocks, far away from any water. And the
| residual radioactive products rapidly decay into being
| harmless with 6 months. Any induced radioactivity from the
| neutrons produced during the explosion will follow a fairly
| predictable pattern as well.
|
| This can be done.
|
| In exchange we get a reactor that creates nearly limitless
| power for entire countries.
| cogman10 wrote:
| Or we could chose a number of WAY safer fission reactors
| for the same cost and same power output (Pick your
| favorite Gen IV reactor).
|
| We also don't end up creating a literal nuclear weapons
| manufacturing plant in every nation that wants to use
| this (since the "fuel" for this reactor is constantly
| detonating nukes).
| cinntaile wrote:
| Why not Gen III+, these are ready to go whereas most Gen
| IV reactors are still in the drawing board possibly early
| prototype phase.
| cinntaile wrote:
| > We're facing a catastrophe. I and others have described
| elsewhere that the path we're on is much, much worse than
| even the most dire of predictions the IPCC makes.
|
| There are a lot of processes we don't fully understand so
| your claim is hard to substantiate. Also, if that was the
| case then a lot of people would probably just accept
| their fate.
| jandrese wrote:
| Worst case scenario is you blow the doors off of the
| facility and tons of superheated radioactive fluoride
| salts are blasted into the air, along with the vaporized
| particles of all of the workers and the fissile material
| in all of the bombs in the staging areas.
| tlb wrote:
| The same line of reasoning says that we should build
| conventional light- or heavy-water reactors. The risk is
| minimal. And they're (a) tested and (b) much cheaper than
| PACER.
| jandrese wrote:
| The advantage of a PACER setup is that you get a lot more
| bang (heh) per kg of uranium than you do out of a fission
| reactor. But the cost of uranium is not currently a
| problem with our fission reactors. We do have a problem
| with radioactive waste, but even that is way more
| political than it is technical.
|
| I wonder which two senators are going to be ok with
| detonating 32 bombs in their state every day? This isn't
| the 50s, NIMBYs know how to make your life a living hell
| when trying to do anything nuclear.
| barkingcat wrote:
| I suspect worst case scenarios are more about earthquakes
| either natural or human induced
| R0b0t1 wrote:
| But surely the payoff would justify a 10-20x overbuild for
| the containment and research into extremely small payloads,
| no?
| jandrese wrote:
| They actually want to detonate a H-Bomb every 45 minutes,
| all day every day. 32 nuclear explosions every day.
|
| One does have to appreciate how these guys took anti-
| proliferation concerns with the nuclear industry and said
| "fuck it, everyone knows we're only doing this to make
| bombs, so lets make a shit ton of bombs". No more concerns
| about terrorists getting their hands on some yellowcake and
| making a dirty bomb. Now they have a full up H-Bomb factory
| moving so much product that security can get complacent.
| [deleted]
| [deleted]
| tlb wrote:
| It lacks the key advantage of fusion reactors over fission: not
| contaminating its working fluid with radioactive isotopes. For
| something like PACER, you have to extract the heat by running
| the hot fluoride through heat exchangers to run steam turbines.
| This is difficult and expensive to make safe. Like with
| conventional fission reactors, you have to be extremely sure
| your heat exchangers will last 50 years with zero leaks,
| because you can't touch them once the system has been running.
| And leaks are extremely dangerous. So every weld has to be
| triple-inspected and so on.
|
| A second disadvantage is that the parts would undergo constant
| thermal cycling. Conventional reactors are run at a very steady
| output level to handle base load, because turning them up and
| down regularly would cause the moving parts to fatigue and
| crack over time.
| namesbc wrote:
| The project was terminated because there were formidable
| technical issues, it wasn't economically profitable, and there
| was a real possibility of catastrophic failure that could not
| be mitigated.
|
| https://books.google.com/books?id=4QsAAAAAMBAJ&pg=PA18#v=one...
| Manuel_D wrote:
| > Dropping about two bombs a day would cause the system to
| reach thermal equilibrium, allowing the continual extraction of
| about 2 GW of electrical power.
|
| So the idea is to drop 2 nuclear bombs per day to get about as
| much energy as one gets from a pair of nuclear fission
| reactors? I seriously doubt that's cost-competitive with
| fission power.
| pvg wrote:
| It would have meant the end of nuclear arms control and non-
| proliferation efforts, an already difficult process. So yeah,
| that tends to arouse considerable negative responses.
| fffobar wrote:
| Isn't the problem that the fuse for a fusion bomb is a fission
| bomb, and a fission bomb very violently disperses lots of
| radioactive material? What am I not getting?
| areoform wrote:
| It's a sealed chamber underground. And the amount of fallout
| can be controlled. Some fusion designs are "cleaner" than
| others w.r.t. fallout.
|
| From the wiki,
|
| > A typical design called for a 4 m thick steel alloy blast-
| chamber, 30 m (100 ft) in diameter and 100 m (300 ft)
| tall,[9] to be embedded in a cavity dug into bedrock in
| Nevada. Hundreds of 15 m (45 ft) long bolts were to be driven
| into the surrounding rock to support the cavity. The space
| between the blast-chamber and the rock cavity walls was to be
| filled with concrete; then the bolts were to be put under
| enormous tension to pre-stress the rock, concrete, and blast-
| chamber. The blast-chamber was then to be partially filled
| with molten fluoride salts to a depth of 30 m (100 ft), a
| "waterfall" would be initiated by pumping the salt to the top
| of the chamber and letting it fall to the bottom. While
| surrounded by this falling coolant, a 1-kiloton fission bomb
| would be detonated; this would be repeated every 45 minutes.
| The fluid would also absorb neutrons to avoid damage to the
| walls of the cavity.
|
| You can see the general design here, https://nextbigfuture.s3
| .amazonaws.com/uploads/2016/01/zyrEF...
| Enginerrrd wrote:
| You control the detonation with either an engineered or
| natural cavity filled with fluid. You can then use the fluid
| as a big thermal reservoir to run steam turbines. Per
| wikipedia:
|
| >"Dropping about two bombs a day would cause the system to
| reach thermal equilibrium, allowing the continual extraction
| of about 2 GW of electrical power."
|
| Now... the part you're not getting is that if you can do all
| that, you can almost certainly just use conventional fission
| power generation, which is what we really, REALLY need to be
| doing anyway.
| G3rn0ti wrote:
| I thought the end game was aneutronic fusion using lithium and
| deuterium anyway creating only charged particles instead of high
| energy neutrons that are dangerous and damaging to the reactor.
| If nuclear fusion ever wants to be commercially viable, it must
| not depend on tritium.
| DennisP wrote:
| Helion is working on a deuterium/helium-3 reactor, which if it
| works will produce only 6% of its energy as neutron radiation.
| YCombinator was an investor. They've run six reactors and are
| building a seventh now for a net power attempt in 2024.
|
| There are also at least four companies working on proton-boron
| fusion, though all but one are very small. (TAE is the
| exception.)
| silasdavis wrote:
| Whimsy. Is there a sequence of fusion technologies where the
| previous one lights the next one and if the current one goes
| out we're fucked?
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