[HN Gopher] Controlling the nuclear fusion plasma in a tokamak w...
___________________________________________________________________
Controlling the nuclear fusion plasma in a tokamak with
reinforcement learning
Author : 317070
Score : 417 points
Date : 2022-02-17 23:08 UTC (23 hours ago)
(HTM) web link (deepmind.com)
(TXT) w3m dump (deepmind.com)
| [deleted]
| teraflop wrote:
| Via SF&F Stack Exchange, a short story from 1990 with a similar
| premise: https://scifi.stackexchange.com/questions/260530/ai-
| controll...
| aqme28 wrote:
| Technically also the plot of Spider-Man 2. Controlling a
| burning plasma with an AI was Doc Oc's field of study.
| ClassAndBurn wrote:
| And suddenly the plot of one of the better Spiderman movies was
| happening in real life.
| [deleted]
| AceJohnny2 wrote:
| (offtopic)
|
| I'm reminded of Alastair Reynolds' sci-fi short story "Weather"
|
| <spoilers follow>
|
| The twist of the story is that the alien/incomprehensible
| starship drives are controlled by an embedded, augmented,
| disembodied human brain. I've long felt the gimmick was a bit
| silly because what system would require an actual human brain
| over a normal control algorithm.
|
| Well...
| mLuby wrote:
| Saw the headline, immediately thought of the same short story.
| Excerpts where they encounter said brain: "It's
| a monstrosity." "Not to us," she said sharply. "We see a
| thing of wonder and beauty." "No," I said firmly. "Let's
| be clear about this. What you're showing me here is a human
| brain, a living mind, turned into some kind of slave."
| "No slavery is involved," Weather said. "The mind chose this
| vocation willingly." "It *chose* this?" "It's
| considered a great honour. Even in [our] society, even given
| all that we have learned about the maximization of our mental
| resources, on a few are ever born who have the skills necessary
| to tame and manage the reactions in the heart of a
| [star]-drive." ... "The degree of concentration is
| quite intense. He can barely spare any resources for what we
| might call normal thought. He's in a state of permanent
| unconscious flow, like someone engaged in an enormously
| challenging game. But now the game has begun to get the better
| of him. It isn't fun anymore. And yet he knows the cost of
| failure." ... "It'll be more like one very long
| dream. Someone else's dream, certainly, but I don't doubt that
| there'll be a certain rapturous quality to it. I remember how
| good it felt to find an elegant solution, when the parameters
| looked so unpromising. Like making the most beautiful music
| imaginable. I don't think anyone can really know how that feels
| unless they've also held some of that fire in their minds. It's
| ecstasy, Inigo, when it goes right." "And when it goes
| wrong?"
|
| Definitely worth reading.
| duvenaud wrote:
| This is a bit off-topic, but can anyone here explain the expected
| economic advantages of fusion power over fission? My
| understanding is that fusion plants would also use heat-driven
| turbines, and be pretty capital intensive. Would they fill a
| different niche, or are they expected to be fundamentally more
| cost-effective?
| vermilingua wrote:
| OpEx > CapEx
|
| Yes, fusion is considerably more capital intensive than fission
| power, but the fuel is just water. You don't need to worry
| about digging the fuel out of the earth, maintaining a costly
| disposal scheme for hazardous waste, etc.
| TheSpiceIsLife wrote:
| Where does tritium come from?
| willis936 wrote:
| Li6 fission in between the first wall and confinement
| coils.
|
| If you want some details: check out section 3.2 of the ITER
| research plan.
|
| https://www.iter.org/doc/www/content/com/Lists/ITER%20Techn
| i...
| sanxiyn wrote:
| This is where tritium _will_ come from, but not where it
| does now.
| willis936 wrote:
| Oh. I'm pretty sure it will be the same place most of the
| current tritium gas comes from: CANDU.
| sanxiyn wrote:
| ITER plans to test breeding tritium from lithium. It should
| work in theory, but there is no practical experience yet.
| Current tritium used in fusion research is entirely
| produced from fission reactor moderated by heavy water, and
| there is only one production facility in the world at
| Canada.
| duvenaud wrote:
| Thanks, but is the fuel cost a significant factor in fission
| plants? And the waste disposal? There's already lots of
| radioactive material in the ground, after all, for example in
| uranium mines.
| colinmhayes wrote:
| Building one power plant is incredibly expensive. Building
| it again costs less. Building it 1000 times costs much less
| per plant. We're not building thousands of fission plants
| because of politics. Fusion might be an easier sell.
| sanxiyn wrote:
| This isn't really true. Yes first of a kind is expensive
| and there is learning curve, but learning is serial and
| iteration cycle is long. You can't build 1000 plants in
| parallel and learn 1000x. Solar power cost is falling
| fast because iteration cycle is short.
|
| South Korea built 28 reactors over 36 years and cost fell
| 1.5% per year, totalling 40% reduction. Even with this
| South Korean nuclear power is only about as half cheap as
| solar power locally (as of 2020), and South Korea is a
| very poor country for solar power considering its
| latitude and weather.
| sanxiyn wrote:
| Fuel cost is not significant, waste disposal even less so.
| (In fact, usual accounting of nuclear fuel cost includes
| waste disposal cost. People argue cost is not accounted in
| full, but as accounted, waste disposal typically costs 1/6
| of fuel cost.)
|
| In terms of cost, 80% of nuclear power is CAPEX. Among
| OPEX, about 1/3 is fuel, rest is operation and maintenance.
| So from total cost, about 6% is fuel, and about 1% is waste
| disposal.
| ncmncm wrote:
| Still, fission operational expense is very, very large
| when compared to solar and wind, which _also_ have
| radically lower capital cost. Operational expense of
| neutron-emission fusion would be radically _more_ than
| for fission: not for the fuel, but for everything else.
| The_rationalist wrote:
| Nuclear byproducts storage (let's not call it waste since MOX
| fuel is the future for humanity) do not cost much, it's not a
| point that is salient enough to male fusion relevant in any
| way.
| conradev wrote:
| Helion is trying to capture the energy directly using the
| magnetic confinement field instead of a heat-driven turbine
|
| I am not sure if any of the other designs avoid the turbine
| KiwiJohnno wrote:
| A completely different approach to fusion that may or may not
| work but can do direct generation of electricity without a
| turbine is pollywell fusion
| ncmncm wrote:
| But, even less is being spent on that than on other
| aneutronic designs, which themselves are on shoestring
| budgets. Theoretical reasons make it seem like an
| unpromising avenue.
| willis936 wrote:
| Confinement approaches aren't inherently neutronic or
| aneutronic. What matters is the temperature, desnity, and
| confinement time (lawson criterion). Get it sufficiently
| high then DT becomes a breeze. Get it a factor of 500
| higher and pB11 is on the table.
|
| No one serious talks about aneutronic fusion because we
| need to walk 1 mph before we sprint at 500 mph. We'll
| seriously discuss aneutronic fusion in 200 years when
| it's relevant.
| willis936 wrote:
| Which will never work because of conduction losses in the
| coils. You can't just put solid materials inside your
| confinement volume and expect to make power.
| [deleted]
| torginus wrote:
| Not an expert, but off the top of my head:
|
| - The end product of Deuterium + Tritium is regular, stable
| Helium, making waste disposal both safe, and cheap
|
| - The input of the process, heavy water, while not safe, is way
| less dangerous than thorium or uranium
|
| - The whole process is no way involved with nuclear weapons,
| making security concerns much less relevant
|
| - Since the process produces magnetically charged plasma, steam
| turbines are not necessary, a solution of directly harvesting
| energy with electromagnets was proposed.
| epgui wrote:
| (Note that you can drink a lot of pure heavy water without
| worrying about any health impact. I still wouldn't recommend
| it, but bad things would be unlikely to happen by accident.)
| aunty_helen wrote:
| Cody's Lab where he drinks heavy water:
| https://www.youtube.com/watch?v=MXHVqId0MQc
| dzhiurgis wrote:
| My partner was part of breast feeding study where she had
| to drink some of the heavy water.
|
| People, especially mothers were somewhat worried about
| magic heavy chemical water with different nuclear
| properties...
| nomel wrote:
| > magic heavy chemical water with different nuclear
| properties...
|
| That seems a bit dismissive. I would naively assume that
| there have been exactly zero studies to see if there are
| any problems with babies drinking heavy water, beyond
| some LD50 extrapolation.
| dzhiurgis wrote:
| Your typical crunchy mom won't know what any I'd these
| words mean, let alone randomised controlled trial. So yes
| I'm dismissive and sexist.
|
| But there's tons of inert things that we don't need to
| study because it makes no sense.
| nomel wrote:
| It doesn't appear that heavy water is biologically inert:
|
| https://en.wikipedia.org/wiki/Heavy_water#Effect_on_biolo
| gic...
|
| From reading that, it seems the mechanisms aren't really
| understood.
| ncmncm wrote:
| You would die if you drank heavy water for long enough.
| But it is very expensive, so you could not afford to buy
| that much.
| 323 wrote:
| > _You could consume a single glass of heavy water without
| suffering any major ill effects, however, should you drink
| any appreciable volume of it, you might begin to feel
| dizzy. That 's because the density difference between
| regular water and heavy water would alter the density of
| the fluid in your inner ear_
|
| https://www.thoughtco.com/can-you-drink-heavy-water-607731
| systemvoltage wrote:
| Missing, arguably the most important factor: It is not a
| runaway reaction. You don't need a giant pool of water with
| functioning pumps to mitigate a disaster. There are some
| newer designs that are self-regulating but surprised to see
| this is not at the top of the list.
| u320 wrote:
| It's not possible to have a runaway reaction in a light
| water reactor either. The major incidents (TMI and
| Fukushima) happened as the reactor cooled down. It's just
| that the power output of the decay heat is enough to cause
| problems.
| ridgeguy wrote:
| Heavy water is not a radiological hazard, but it's toxic [1].
| I doubt there have been definitive experiments on humans (for
| obvious reasons). I wouldn't try substituting it for ordinary
| water.
|
| [1]
| https://en.wikipedia.org/wiki/Heavy_water#Effect_on_animals
| MagnumOpus wrote:
| It is toxic when you ingest >20% of your body weight. Let's
| just say that that sort of thing won't happen by accident.
|
| (And to point out the obvious, every other liquid apart
| from drinking water is _more_ toxic when you ingest literal
| bucketfuls, including harmless household liquids like
| vinegar, shampoo, ethanol, olive oil.)
| vimacs2 wrote:
| > - Since the process produces magnetically charged plasma,
| steam turbines are not necessary, a solution of directly
| harvesting energy with electromagnets was proposed.
|
| But wouldn't that require aneutronic fusion to be viable? I
| had thought that the prevalence of neutron radiation
| otherwise would have made directly tapping the plasma for
| electricity impractical.
| ncmncm wrote:
| Yes. But mostly aneutronic fusion is possible, in
| principle.
|
| "Side reactions" produce neutrons and gamma rays, and
| fusion products can get involved in side reactions too,
| also producing neutrons and gamma rays. If you can keep
| recirculating the desired reactants, filtering out the
| products and side products, those reactions can be kept to
| a low level.
| alextingle wrote:
| Direct harvesting is not possible with the fusion reactions
| we are currently working on. The products are electrically
| neutral, so the only way to harvest the energy is as heat.
|
| Helium-3 fusion produces charged particles, which it might be
| possible to directly harvest as electricity. The He3 fusion
| reaction has a high activation energy, which is currently
| unachievable, and there is no Helium-3 on Earth. We'd have to
| get it from space, somehow. (The movie "Moon" was set on a
| Helium-3 mining outpost on the Moon.)
| gpm wrote:
| > Direct harvesting is not possible with the fusion
| reactions we are currently working on
|
| Depends on which company you're talking about.
|
| Helion, for a coutner example, is directly harvesting
| energy out of plasma.
| ncmncm wrote:
| "Hopes someday to be"
|
| Not the same as "is".
| gpm wrote:
| Hellion _is_ extracting energy out of plasma.
|
| Hellion hopes someday to be extracting more than they put
| in.
| u320 wrote:
| But Helion is not using the reactions they are currently
| working on.
| DennisP wrote:
| Conveniently, pure deuterium fusion (D-D) is easier than
| D-He3 fusion, and the output of D-D fusion is half He3, and
| half tritium which decays to He3 with a 12-year half-life.
| So if we can get net power from He3, we can make He3 from
| deuterium and generate energy in the process.
|
| D-D fusion does produce neutrons but they're much lower
| energy than D-T neutrons. Fusion startup Helion is working
| on a hybrid D-D/D-He3 reactor, saying the combination will
| produce only 6% of its energy as neutron radiation, low
| enough so they can do direct conversion.
|
| They've built half a dozen reactors, and now they're
| working on a seventh that they'll use for a net power
| attempt around 2025. They recently had a fundraising round
| led by Sam Altman, and raised $500M with another $1.7
| billion of commitments based on milestones.
|
| https://techcrunch.com/2021/11/05/helion-series-e/
| ksec wrote:
| Sounds too good to be true? 2024 commercialisation, size
| of shipping container and direct to electricity
| generation?
|
| Surely we are missing something in this discussions?
| ncmncm wrote:
| There is no usefully available Helium-3 on the moon,
| either. The only practical source known is decay of
| tritium, which must itself be synthesized by nuclear
| reaction, and is, for military use.
|
| Another choice is fusion of ordinary hydrogen, usually
| labeled "p" for the proton, with boron, B, thus "pB". But
| that is even harder to achieve. Still, it is being worked
| on.
|
| There is no route to commercially viable fusion extracting
| heat from Tokamak reactors, as any such reactor would need
| to be enormously bigger and much more expensive to operate
| than the same-rated fission reactor, which is not today
| competitive, and gets less so all the time.
|
| Some people hope that something can be learned from Tokamak
| work that might be applicable to potentially practical
| designs, but the money is all going to Tokamak, while the
| others mostly go begging.
| gweinberg wrote:
| I think you need a fission reactor to get the tritium.
| ncmncm wrote:
| Or fusion, if you can achieve it.
| zamalek wrote:
| > stable Helium, making waste disposal both safe, and cheap
|
| Even better. Helium is a relatively scarce resource, there
| would be no shortage of people to take it off of your hands.
| YetAnotherNick wrote:
| The amount of helium will be much lesser than what you
| think it is. If we produce all the energy in the world
| using fusion, it will create less helium per day than a
| tank used by kids helium balloon shop.
|
| > If one ton of deuterium were to be consumed through the
| fusion reaction with tritium, the energy released would be
| 8.4 x 10^20 joules[1]
|
| That's 0.84 exajoule(233 TWh) per kilo of deuterium or 0.42
| exajoule(117 TWh) per kg of helium produced. World energy
| consumption is 1.6 exajoule per day[2] so less than 4 kg
| helium will be removed per day if energy extraction is
| perfect or few 10s of kg assuming imperfection
|
| [1]: https://www.britannica.com/science/nuclear-
| fusion/Energy-rel... [2]:
| https://www.statista.com/statistics/265598/consumption-of-
| pr...
| willis936 wrote:
| These numbers don't jive with my understanding. It's
| about a factor of 2,500x higher.
|
| https://news.ycombinator.com/item?id=30277024
| Retric wrote:
| Your energy estimate is off, but also ~10kg of helium is
| ~56 cubic meters or ~2,000 cubic feet that's several
| large helium tanks which run around 291 cubic feet as
| that's a serious pain to move around without a hand
| truck.
|
| Actual fuel fuel estimate: "a 1000 MW coal-fired power
| plant requires 2.7 million tonnes of coal per year, a
| fusion plant of the kind envisioned for the second half
| of this century will only require 250 kilos of fuel per
| year, half of it deuterium, half of it tritium."
| https://www.iter.org/sci/FusionFuels
|
| "Global electricity consumption in 2019 was 22,848
| terawatt-hour"
|
| 22,848 * 1000 / 365 / 24 = 2608 different 1GW reactors
| each producing 250kg of helium per year. So 652,000
| kg/year if all the worlds electricity was made from
| fusion or ~3,650,000 cubic meters or ~130,000,000 cubic
| feet of helium.
|
| PS: Efficiency numbers could wildly change those
| estimates, but that's the rough ballpark for electricity
| let alone stuff like transportation or home heating etc.
| YetAnotherNick wrote:
| You are talking if helium is stored in atmospheric
| pressure. It is generally sold compressed like all other
| gas. Search google for 10kg helium tank. In my area it is
| available for $30.
| Retric wrote:
| That's the weight of the tank not the helium inside it.
| They should advertise it as filling ~30 helium balloons.
| Which obviously weigh far less than 10kg or they wouldn't
| float.
|
| The ~300 cubic foot tanks are 9 inches in diameter, 55
| inches tall, with about 130 pounds and contain about
| 1.5kg of helium.
| dr_dshiv wrote:
| What. The. F.
|
| New level of appreciation. Thank you.
| Drblessing wrote:
| > The whole process is no way involved with nuclear weapons,
| making security concerns much less relevant
|
| The most important factor.
| giarc wrote:
| I think I heard on a podcast the other day that a 10ft x 10ft
| tank of heavy water would produce the same amount of energy
| the entire world consumes in a year (or some crazy stat like
| that).
| DennisP wrote:
| That sounds plausible. The heavy water in your morning
| shower could provide all your energy needs for a year.
|
| https://dothemath.ucsd.edu/2012/01/nuclear-fusion/
| eatmyshorts wrote:
| Another big one is the default-to-safety nature of fusion vs.
| fission. With fission, if things go wrong, the nuclear
| process often speeds up and can run out of control. With
| fusion, generally when things go wrong temperatures dissipate
| and the fusion process halts naturally.
| anonymousDan wrote:
| I think the main advantage of fusion is they are not
| susceptible to Chernobyl style meltdowns line fission reactors.
| retrac wrote:
| There are no proliferation concerns with fusion. You can't make
| a nuclear bomb with a fusion reactor. They'll be largely free
| of the nuclear materials and technologies handling and export
| regulations. Quite a few international deals for fission plants
| over the years have been scuttled over concerns about
| misapplication of the reactors or fuel.
| ggm wrote:
| Any reaction which emits neutrons is capable of being used to
| feed breeder-reactor cycles.
|
| Nuclear fusion emits neutrons.
|
| If you can soak up surplus neutrons in uranium 238 you can
| breed plutonium 239.
|
| By _design intent_ fusion does not intend making fission
| happen. A side effect of the nuclear physics makes fission
| products, if you _want to_.
|
| You can make weapons grade fission materials, with neutrons
| from a fusion reactor.
| willis936 wrote:
| You need to start with fissile material to make weapons
| grade fissile material. If there is no peaceful application
| for fissile material then a global ban treaty complete with
| trust-but-verify policies is within the realm of reason.
|
| Regardless of this hypothetical: the fact remains that no
| part of a fusion reactor increases weapons proliferation
| risks, unlike a fission reactor. You could plop one down
| anywhere on the planet and locally source fuel.
|
| If you want a neutron source then you can make one in your
| basement with a fusor or linear magnetic mirror.
| melony wrote:
| There actually is proliferation concerns, maybe even worse.
| KiwiJohnno wrote:
| Can you elaborate? Fusion reactors don't produce any
| fissionable material.
| ncmncm wrote:
| One is not _obliged_ to turn ordinary, mined uranium into
| weapons-grade stuff, in a neutron-emitting fusion system,
| but you could if you cared to.
|
| I.e., a nation that had control of such a fusion plant
| would have little difficulty attaching an enrichment
| process without interfering with power output.
|
| _Fortunately_ , no economically practical power
| generation system can be built using hot-neutron fusion,
| so it is an idle concern, but almost all the money being
| spent on fusion pursues that impractical goal.
| willis936 wrote:
| It's an idle concern because fast neutron sources are
| cheaply available without fusion reactors.
| remarkEon wrote:
| In what way? Are you implying e.g. materials science
| advances will lead to non-nuclear weapons proliferation?
| 317070 wrote:
| All of these points are up for debate of course, but:
|
| * compared to fission, the nuclear waste management for fusion
| looks to be done within a human generation, rather than outlast
| human civilisation. So how you discount the future has a large
| impact on the trade-off between fusion and fission.
|
| * the fuel for fission is uranium, a hard to get and limited
| resource. The fuel for fusion is hydrogen. Initially only the
| rarer hydrogen isotopes, but we might eventually get fusion to
| work for the more common isotopes as well.
| duvenaud wrote:
| Okay, but is the fuel a major cost for fission plants? And
| it's not clear to me how nuclear waste can both be extremely
| long-lived and also very dangerous that entire time.
| flaviut wrote:
| > And it's not clear to me how nuclear waste can both be
| extremely long-lived and also very dangerous that entire
| time.
|
| This is a really good question, and as someone who knows
| nothing about this, here's what I've found:
|
| There's 4 kinds of nuclear waste:
|
| - Very low-level waste
|
| - Low-level waste
|
| - Intermediate-level waste
|
| - High-level waste
|
| You just dump very low-level waste into a landfill[1]. This
| stuff is basically random concrete, etc. that comes from
| demolishing a nuclear power plant.
|
| Low-level waste is still pretty boring stuff like clothing
| and rags that got irradiated somehow, and is 90% of the
| volume and 1% the radioactivity of radioactive waste[1].
| The radioactivity in this mostly comes from atoms with a
| half-life of less than 5 years, although it seems like
| trace amounts of slightly long-lasting radioactive isotopes
| are allowed[2].
|
| Intermediate-level waste looks like it's pretty varied
| things: sludges, fuel cladding, reactor parts from
| decomissioning. It's 7% of the volume and has 4% of the
| radioactivity[1]. Looks like this stuff is generally pretty
| long-lived: takes about 1000 years to become 10x as
| radioactive as low-level waste, and 100k years to become as
| radioactive as low-level waste.
|
| High-level waste is basically spent fuel. It's special in
| that it requires some kind of cooling, at least for a few
| decades. It's 3% of the volume and 95% of radioactivity[1].
| It can often be re-processed into more fuel. After about
| 200 years, it becomes about as radioactive as intermediate-
| level waste, and 100k years to become as radioactive as
| low-level waste.
|
| [1]: https://world-nuclear.org/information-library/nuclear-
| fuel-c... [2]: https://en.wikipedia.org/wiki/Low-
| level_waste [3]:
| https://www.radioactivity.eu.com/site/pages/ML_LLW.htm [4]:
| https://www.radioactivity.eu.com/site/pages/HLW_Waste.htm
| lazide wrote:
| Fuel is not a major cost of fission plants.
|
| Nuclear waste is not actually that dangerous that long.
| Everyone (including the planners) like to hype it up for
| their own reasons.
|
| Fusion has many fusion pathways, some of which are pretty
| light on the dangerous radiation, others that are pretty
| heavy on it. Most advocates don't know which one they're
| advocating for.
|
| The radiation 'activates' and damages the interior of the
| fusion reactor, making it radioactive. This is not a solved
| problem yet. It may never be.
| duvenaud wrote:
| It sounds like you're pretty knowledgeable on this topic
| - care to speculate about the economic pros and cons of
| fusion vs fission?
| lazide wrote:
| Near as I can tell, no one has yet gotten to the point of
| having a somewhat plausible guess at cost/watt for
| fusion, so it's a moot point.
|
| All reactors are still at best early scientific
| experiment level, and have been for some time.
|
| Fission exists now, and we understand the economics. With
| all the political friction and the like, the west
| basically builds no new plants.
|
| So we'd be comparing 'no clue it's even possible to build
| a plant' to 'expensive and generally not building new
| ones'
| ascar wrote:
| > Nuclear waste is not actually that dangerous that long.
| Everyone (including the planners) like to hype it up for
| their own reasons.
|
| Can you elaborate? E.g. Plutonium-239 has a half life of
| 24000 years. That hardly sounds like "not that long"?
| Leftover uranium-238 even stays radioactive for billions
| of years (half life of 4.5 billion years).
| lazide wrote:
| The more radioactive it is, by it's very nature, the
| shorter it's half life. That is literally what is going
| on. Decay means release of radiation. Decay means less of
| the original radioactive material.
|
| Some of these elements have pretty high overall energy
| levels released in their decay chains (so it's not just
| one decay) some less - but sources that are more
| radioactive are decaying and releasing energy faster,
| have shorter half lives, and are very dangerous for
| shorter periods of time.
|
| You can literally buy Uranium 238 ore through the mail
| and handle it with no more special precautions than
| washing your hands afterwards and not eating it. It's
| seriously fine.
|
| Except in a few spots where it was heavily concentrated,
| most of the legitimately dangerous stuff has decayed to
| 'meh, not that bad' levels already even at Chernobyl.
|
| It's still not a good idea to lick it, or spend all your
| time in the main reactor hall, but give it another 50
| years and you'll probably be able pet the elephants foot
| on a tour.
|
| Hiroshima and Nagasaki has been fine for awhile. People
| do tours at ground zero of the Trinity test site.
|
| Some of these elements are chemically active in weird
| ways, and even without the radioactivity, eating
| plutonium, cesium, or uranium will be a bad time. Same
| with mercury, lead, cadmium, etc. so I'm not advocating
| for being careless with them.
|
| But the idea of a big chunk of radioactive waste being a
| glowing orb in 10k years is fantasy.
| ncmncm wrote:
| Plutonium, anyway, is not waste, but fuel. And weapons
| material.
|
| But there are other long-lived isotopes, as well. Safe
| disposal is not a difficult technical problem, but is a
| political football causing limitless distraction.
| 317070 wrote:
| Fuel is not a major cost right now, but it inevitably will
| be at some point. Current estimates are that we have 80-250
| years of uranium left [0], so we could use a different
| energy source for the long run.
|
| The difference in radioactive danger, is because not all
| nuclear reactions are treated equally. Tritium decays once,
| emitting a 0.019MeV beta particle [1]. Uranium creates an
| avalanche of particles [2] for a total of 51.7 MeV. So it
| has the leeway to be both more radioactive and to be it for
| longer. But both the type and energy of the radiation have
| intricate effects on how they interact with biology and so
| how dangerous they really are.
|
| That said, exactly how radioactive fusion waste will be is
| a bit a philosophical problem, as nobody knows what the
| minimal requirements are for a functional plant.
|
| [0] https://bettermeetsreality.com/how-much-uranium-is-
| left-in-t... [1] en.m.wikipedia.org/wiki/Tritium [2]
| https://en.m.wikipedia.org/wiki/Decay_chain
| duvenaud wrote:
| Finally some numbers! Thank you. So again, this sounds
| like more evidence against an economic advantage of
| fusion over fission, is that correct in your opinion?
| flaviut wrote:
| FYI the bettermeetsreality site you link to is SEO spam.
|
| But anyway, those numbers sound about right, here's what
| wikipedia (and their source,
| https://doi.org/10.1787/uranium-2018-en) says:
|
| > As of 2017, identified uranium reserves recoverable at
| US$130/kg were 6.14 million tons (compared to 5.72
| million tons in 2015). At the rate of consumption in
| 2017, these reserves are sufficient for slightly over 130
| years of supply. The identified reserves as of 2017
| recoverable at US$260/kg are 7.99 million tons (compared
| to 7.64 million tons in 2015).
|
| I wouldn't be too worried right now though, because Table
| 1.1 in uranium-2018 shows that the known recoverable
| uranium sources @ $40/kgU grew 50% between 2015 and 2017,
| and known recoverable uranium sources @ $80/kgU grew 4.6%
| over the same time period.
|
| No one's going to go around prospecting unless they think
| they can make a profit doing it.
| u320 wrote:
| The fuel for DT fusion is heavy water and lithium. Everyone
| leaves out the lithium part for some reason. They are
| considerably more rare than hydrogen. But more common than
| uranium for sure.
| stocknoob wrote:
| Lithium is more common than lead (https://en.wikipedia.org/
| wiki/Abundance_of_elements_in_Earth...). If fusion required
| heavy water and lead, would you care that it was left out
| as an ingredient?
| axg11 wrote:
| As the other commenter mentioned, fuel is limitless and the
| waste product doesn't need special disposal. This isn't just a
| technical advantage over fission, but also a political one.
|
| In its current form though, the CapEx for fusion projects is
| huge. Fusion won't play a big part as an energy source if
| reactors take 10+ years to come online and cost tens of
| billions of dollars. Fusion proponents will argue that costs
| will come down, but if the political and entrepreneurial
| pressure to reduce cost isn't there, fusion will end up the
| same as fission.
| duvenaud wrote:
| Thanks. So it sounds like you're saying that, unless there is
| some radically different plant design in the future, that
| there won't be an economic advantage to fusion over fission,
| at least in the near term.
| aqme28 wrote:
| "In the near term" doesn't really make sense for fusion. It
| won't be economical at all in the near term.
| colinmhayes wrote:
| Well fission energy would be much cheaper if most of our
| energy was produced that way. Economies of scale provide
| huge opportunities that are currently limited by political
| will. I don't see a reason fusion can't quickly become a
| large scale source of power, because unlike fission, there
| would be much less political backlash.
| sanxiyn wrote:
| I am sad to report that in South Korea, which produces
| fission power very well and does excellent fusion
| research, the leading anti-nuclear activist (also a
| member of congress) is vocally against fusion and already
| proposed to cut 100% of fusion research budget in 2018.
| (People thought that's too extreme so she haven't
| repeated it so far, but I don't think her position
| changed in any way.)
| ncmncm wrote:
| Being against wasting tax money is a principled stance.
| There is no possibility of current work leading to
| practical power on a time scale of less than multiple
| decades, and even then only if a mostly aneutronic form
| is achieved, which very few are working on.
| anonymousDan wrote:
| This is still not wasted money. We would all still be
| sitting around scratching our asses in caves with that
| attitude to scientific research.
| duvenaud wrote:
| Thanks. So it sounds like there isn't an economic
| advantage of fusion over fission, except indirectly
| through less political opposition.
| ncmncm wrote:
| Right, the current crop of Tokamak designs getting the
| lion's share of funding would cost much more than 10x,
| per watt out, than fission, and the reactors would cost
| that much more to build, besides. Since fission is
| uncompetitive, that kind of fusion is completely
| impractical.
|
| Such reactors would also quickly destroy themselves, so
| would have no opportunity to pay back the investment.
|
| The only hope for useful fusion is if work on existing
| designs turns out to be applicable to actually practical,
| aneutronic forms. Current spending on those is
| negligible.
| 2wrist wrote:
| Is that to run or to build currently? And is this not due
| to the fact that fission is an exisitng technology and
| fusion new? The new technology would be much more
| expensive until it becomes know and then it the price
| comes down as they understand how to build it more
| effiently.
| duvenaud wrote:
| Thanks for actually answering my question! I guess no one
| wants to be a downer, but I'm pretty shocked that no one
| else in this thread, or that I've talked to about this
| issue, or anything I've read about fusion, has mentioned
| that current designs aren't on track to be remotely cost
| effective, which is what you seem to be saying.
| ncmncm wrote:
| Most people think the fusion idea is cool enough to be
| enthused over, and assume all the deep technical
| difficulties, beyond actual fusing itself, will
| evaporate, because that would be cool too.
|
| Consider that the majority of startup companies with
| apparently good ideas never get to market. People like to
| think the hardest problem they know of _right now_ is all
| that matters, but often it is a boring problem that sinks
| the company. Maybe it is technically solvable, but costs
| enough to destroy the value proposition.
|
| So long as solar and wind costs are still falling fast,
| any prediction about the viability of competing tech is
| at best provisional.
|
| Solar and wind benefit from the opposite effect: there
| are known problems, but they have lots of known viable
| solutions that are just competing for which ones (plural)
| will end up cheapest, or have the most side benefits, or
| are easiest to deploy.
|
| It used to be that poor round-trip efficiency would sink
| a storage technology, but generation has become so cheap
| that losses matter less than other considerations. 50%
| loss? Build out more panels!
|
| Hydrogen still has awful efficiency, electrolysers and
| fuel cells need platinum-group metals, and liquid
| hydrogen needs really rigorous handling, but H2 is so
| useful that those don't matter. Efficiency and cost will
| only improve. Ammonia synthesis is similar: super-useful,
| but maybe easier to make starting with water. (There will
| be a _lot_ of waste oxygen soon.)
|
| Iron-air batteries likewise have poor efficiency, and low
| discharge rate, but the material basis is very, very
| cheap. You can gang up thousands in parallel to get the
| rate you need, and stick lithium or lead cells on the
| front to handle load spikes. Useless for cars, fine for
| utilities.
|
| Liquifying air is very mature tech, so as the basis for a
| storage medium it's a safe bet. Storage capacity grows
| with cheap tankage. And, excess LN2 is valuable, so when
| your tanks are full you still have revenue.
|
| It turns out there are myriad elevated basins that would
| be perfect for pumped hydro storage, another very mature
| technology. Unlike hydro generation, you don't need a
| whole watershed and river valley, just hills with a dip.
|
| Even if fusion fizzles for utilities, the _mostly_
| -aneutronic sort might be perfect for outer solar system
| propulsion, where a completely different set of
| constraints apply. And, military deployments will often
| not be able to lay out much solar where they land. So,
| even though fission is, relative to solar, super-
| expensive, places can be found where nothing else will
| do.
| skywal_l wrote:
| You make an interesting point and I am myself absolutely
| not knowledgeable in that field but there are some
| obvious points that you elude in your response.
|
| Fission (will?) have the advantage of being able to
| produce energy whenever we need it. Solar or wind need
| storage. And as far as I know, there are no viable
| storage solution as of today.
|
| > It turns out there are myriad elevated basins that
| would be perfect for pumped hydro storage, another very
| mature technology. Unlike hydro generation, you don't
| need a whole watershed and river valley, just hills with
| a dip.
|
| In some countries, all possible places of hydro
| generation have already been used. What would be the
| potential for new hydro solutions in Europe for example,
| where hydro has been exploited for decades? Again, not an
| expert, but I don't think that there is an obvious path
| in countries where population density is pretty high and
| without large swathe of lands, to build hydro storage to
| be able to produce enough energy on a sufficient long
| period of time. Curious to know what you think.
|
| Using any sort of battery, based on a chemical process,
| will also probably have high impact on the environment.
| Current battery relies on rare earth material or
| industrial processes that are very impactful. Creating
| enough batteries to ensure safe power distribution for
| billions of people will probably be terrible for the
| environment.
|
| My point is that there is no silver bullet as of now so
| putting all you eggs in the same basket does not seem to
| be a sane strategy. Investigating fusion is worth a shot
| I think.
|
| And if we worry about money, there's plenty of money to
| go around. We are talking about the survival of
| civilization here. 16 billions were poured into the a
| company providing ways to share pictures of your baby to
| your high school friends ten years ago (yes Facebook). I
| am sure we can find the money to finance Fusion AND
| research on energy storage. It's a question of political
| will. In the end, we'll get what we deserve...
| ncmncm wrote:
| It seems you did not even read the parts you quoted. Try
| reading what I already wrote, and you will have your
| answers.
| mchusma wrote:
| Fusion definitely has long term economic advantages over
| fission. The fuel is the most plentiful in the universe
| and the energy released from fusion is much higher than
| fission.
|
| The chart here shows the energy difference pretty well:
| https://www.nuclear-power.com/nuclear-
| power/fission/nuclear-...
|
| More fuel + more energy from fuel = superior for most
| uses long term. If we pull it off.
| duvenaud wrote:
| Okay, but the other commenters are saying that fuel is
| around 6% of the cost of running a fission plant. Do you
| really think fuel availability will be a decisive factor
| in say, the next 60 years?
| ncmncm wrote:
| In a word, no.
|
| Fission is already not competitive, so a technology much
| more expensive to build and operate is even less so. In
| ten years, solar and wind will be even cheaper than
| today, and will be supplying most of our energy needs.
| MagnumOpus wrote:
| Fission is non-competitive only because governments don't
| want it to be. France's nuclear fleet built in the
| 60s/70s with more primitive tech has capital/operating
| costs of 7c/kWh, which is fairly similar to commercial
| solar or wind in France - and is the cheapest option once
| you double the cost of the latter to account for extra
| storage/smart grids/other intermittency handling.
|
| (Not every place is Southern California where there are
| no clouds and the sun shines all year. Solar is cheap in
| some places, but not at high latitudes.)
| willis936 wrote:
| To tack on to the last sentence: "as long as there is fossil
| fuel to burn".
| markvdb wrote:
| As you say, fusion technology inherently has less need for
| strict regulation. Less harmful waste. Less runaway reaction.
| Less arms proliferation.
|
| This potentially creates room for fusion that never existed
| for fission:
|
| - innovation and entrepreneurial pressure. Best case, we get
| SpaceX efficiency fusion innovators versus SLS pork barrel
| subsidy patients.
|
| - insurability. Fusion energy production might become
| privately insurable.
|
| - political support. If the political buyin required is
| mainly limited to capex, that's a very big advantage versus
| fission.
|
| As for short to medium term political motivation, one might
| hope fusion energy research is to benefit from the tension
| between Russian and western leadership.
| willis936 wrote:
| On the political motivations: one can hope. My view of
| things at this point is that those with power in the global
| playing field want to maintain it. Both Russia and the US
| supply the world with a lot of oil. This grants a lot of
| political power. If you make oil obsolete then you remove
| your lever.
|
| This sounds like a great thing for humanity, but humanity's
| interests are not properly represented by the existing
| political power structures.
| manholio wrote:
| Too little, too late. The traditional fission industry is being
| killed by high CAPEX and nothing about the current tokamak based
| designs suggests they will be any cheaper to build for a given
| power rating:
|
| - They need large, highly advanced cryocooled superconducting
| magnets in very close proximity to a hundred million degree
| plasma. This only makes economic sense in massive, and expensive
| plants.
|
| - They are a very strong source of fast neutrons useful to
| transmute cheap depleted uranium into plutonium, so carry massive
| proliferation risks, need close regulatory scrutiny and will
| require mounts of paperwork to operate, thus exceptionally
| inflexible to improvements and rapid iteration. Just like the
| current fission crop.
|
| - Aneutronic fusion is a currently a purely theoretical concept,
| in the last 70 years nobody has been able to contain even the
| much cooler D-T plasma for economically viable durations and
| temperatures.
|
| - The structure of the reactor becomes radiologically active and
| cleanup operations must be considered. Highly penetrating neutron
| radiation means some radiation will escape regardless of
| containment, requiring a radiological exclusion zone. No Mr.
| Fusion in your car, sorry.
|
| - They operate and must breed sensitive nuclear materials -
| Tritium, a well known component of boosted thermonuclear weapons.
| The limited efficiency of tritium production from lithium-6 might
| require obtaining some from fission reactors to top up the fuel
| cycle and keep fusion reactors operating.
|
| So when you draw the line, a life time of magnetic containment
| research has produced a speculative design that even if it were
| to work, which it doesn't, would be, in the best case scenario,
| comparable to existing fission designs that are being phased out
| for cost and risk issues.
|
| A PhD money pit with zero chance of ever building anything
| useful. I know it, you know it, I'm ready for the proverbial
| downvote protecting one's paycheck from their own knowledge.
| Izikiel43 wrote:
| Check Sparc before all that stuff, iter is outdated but there
| are alternatives being worked on.
| manholio wrote:
| When SPARC ignites, 5 years from now, and when it achieves
| long burns at Q=10, after a good few more years, then I will
| redact the " _nobody has been able to contain D-T plasma for
| economically viable durations and temperatures_ " part. The
| rest of the points will probably remain true decades into the
| future, though.
| gameshot911 wrote:
| This is a really nice, well-informed post. Out of curiosity,
| why do you prefer to post it under a throwaway account?
| manholio wrote:
| It's a real account, see my very first post on it for
| details. Sorry, to disappoint, nothing up my sleeve.
| willis936 wrote:
| >The limited efficiency of tritium production from lithium-6
| might require obtaining some from fission reactors to top up
| the fuel cycle and keep fusion reactors operating.
|
| Citation needed.
| manholio wrote:
| Since nobody has yet demonstrated tritium breeding, a
| citation is actually not needed.
|
| There exist purely theoretical models where neutron
| multiplication is used so that the single fast neutron
| generated in a D+T reaction can breed more than a single
| tritium atom when it hits li-6 (which would be clearly
| insufficient to have a self fueling rector).
|
| It's all a complex mess of absorption cross sections and
| neutron spectra, dependent on lithium blanket geometries,
| coolant and structural material parasitic interactions. The
| tritium breeding efficiency today sits at exactly 0% and
| until that changes, concerns that it may never reach the
| required 110% are at least somewhat warranted.
| willis936 wrote:
| From the talks I've been to the targeted performance of
| blankets is 120% and simulations predict this should be
| possible without prohibitively thick blankets.
|
| ITER's TBM will be doing important work to test theory.
|
| It isn't clear to me that external sources of tritium will
| be necessary. Between Li-6 fission and Be neutron
| multiplication there is theoretically plenty of neutrons to
| go around even though they aren't easy to capture.
|
| Viability of blanket breeding hasn't been demonstrated to
| work yet, but my original point is that it hasn't been
| demonstrated to not work. I see now the "might" in your
| statement.
| manholio wrote:
| Sure, by the "it hasn't been demonstrated to not work"
| standard the whole field should generate cheap
| electricity tomorrow. Just that it's so unimaginably,
| fiendishly hard to make it work, perhaps the most
| challenging technical problem in history. It might never
| work, for interesting values of _never_.
|
| My point was that fueling is in itself a very difficult
| and complex problem that has yet to be solved, far from
| the "it runs on seawater" popular tropes.
| dekhn wrote:
| I worked on a previous project that was sort of an ancestor to
| this. We used grid computing (before "cloud" was even a thing) to
| rapidly scale up compute- right after an experiment, you want to
| recalculate the optimal parameters based on what you just learned
| from the experiment and then start over as fast as possible. This
| was well before anybody could say "reinforcement learning" or
| "neural network" around physicists without being pilloried.
|
| The best part was the name of our collaborator- "General Atomics"
| https://en.wikipedia.org/wiki/General_Atomics
|
| Here's a writeup,
| https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.58...
| peteradio wrote:
| Very cool, I came several years following and we too had a grid
| for similar tuning work on LHC. My fondest memories were the
| bizarre hangups that could occur in custom stuff like this, and
| the way you'd find out that you done fucked up. My favorite
| time was when I broke a database by sending an accidental
| "query all the stuff", but it was really stupid, like from the
| console all you had to do was type a partial "ls" and it would
| assume a wildcard. So when the authority in my group attached
| me in the email and said I broke the main monitoring database I
| told them they had stupid defaults and never heard anything
| again. My second favorite memory was when I found a way to gain
| production access to grid resources just by naming your output
| datasets in a particular way. I was sat down in a hush ceremony
| with the Pakistani post-doc from my group and the Russian?
| programmer of the system and asked to keep it quiet. I kept it
| quiet, and am pretty sure I failed some sort of spy test that
| day. It wouldn't be the last time I felt like I failed a spy
| test, I guess that is my third fondest memory from my time in
| grad school.
| dekhn wrote:
| Please tell me you went on to be an SRE. Because you have the
| phenotype.
| peteradio wrote:
| Well, my nickname in my first job out of grad school was
| Murphy (as in murphys law). I was essentially a dowsing rod
| for corner cases and it was very much not intentional and
| extremely distressing. You could say I have some
| experience.
| avs733 wrote:
| I've worked in a number of factories and it seems like
| everyone of them has a Murphy. The people who get
| confronted with problems that begin with everyone saying
| 'thats not actually possible'. I will always remember the
| poor guy who had to figure out the local fire
| department's radio repeater was rebooting ONE SINGLE
| piece of equipment in a factory from about a third of a
| mile away.
|
| I have always wondered if there is a way to detect this
| particular trait either using MRI or possibly smell. Once
| you are in a space you can usually identify them because
| everyone seems to slightly avoid their workspace out of
| fear of being infected.
| jacquesm wrote:
| > I will always remember the poor guy who had to figure
| out the local fire department's radio repeater was
| rebooting ONE SINGLE piece of equipment in a factory from
| about a third of a mile away.
|
| Old relays (especially when switching large DC currents)
| are _fantastic_ for this purpose. The arc will
| essentially give off a mini EMP across the whole spectrum
| and woe to you if your gear isn 't shielded and grounded
| properly.
| [deleted]
| jacquesm wrote:
| I have a family member like that. She walks into the
| room: all computing equipment mysteriously crashes. I
| haven't been able to pin it on a real world cause yet.
| shmageggy wrote:
| Sorry, I don't see how this has any similarity to the posted
| project, apart from being also related to fusion?
| dekhn wrote:
| I'm just an old man, pointing out that it's all been done
| before, and it will all be done again. The big difference is
| it looks like they're in the realtime controller for the
| plasma, rather than determining static settings for a
| subsequent run.
| shmageggy wrote:
| Yours was a tools and infrastructure project, and this is
| about learned, autonomous control. They are completely
| different goals.
|
| > _determining static settings for a subsequent run._
|
| AFAICT, your software didn't do that. Rather it provided
| infrastructure for the researchers to do that themselves
| more efficiently.
|
| From your paper:
|
| > _The ultimate goal of FusionGrid is to allow scientists
| at geographically distributed sites to participate fully in
| experimental and computational activities..._
|
| Exactly what are you saying has been done before?
| fartboi wrote:
| The guy was saying nothing, people have done computer
| work in fusion and they will use computers again!
|
| Profound.
|
| He was merely giving a shameless plug of whatever infra
| project he was involved in.
|
| Congrats - it involves computers and fusion.
| shmageggy wrote:
| I have no problem with a shameless plug -- it's an
| interesting show of how things used to be -- but he
| claimed more than that
|
| > _a previous project that was sort of an ancestor to
| this_
|
| > _it 's all been done before_
|
| implying that the current work build on his work in some
| way, which I don't see.
| fartboi wrote:
| dekhn wrote:
| Could you be a bit clearer why you're being critical?
| Much of what DeepMind does is rooted in prior projects,
| they just sprinkle a little more RL and have a great
| press team. Nobody would use their system for real in
| production, just like when they published how they could
| run Google datacenters 5% cheaper in real time- turns
| out, nobody actually deployed that because the settings
| it came up with don't make sense to humans.
| shmageggy wrote:
| I'm not trying to be critical of your project, sorry if
| it came off that way. I'm just trying to clarify when you
| say "it's all been done before", exactly what in the
| current work had been done in your project. Although they
| are both in the fusion domain, I don't see how the
| current work builds on anything done in your work, even
| in a very distant way.
| regitempus wrote:
| This is super cool, thanks for sharing. Also, you're right,
| that name is dope.
| systemvoltage wrote:
| Silicon valley would name it, ahem... Atomicly. Uber for
| atoms.
| iSnow wrote:
| Since the .com domain would be gone, it would most likely
| be Atomcly
| nr2x wrote:
| Love the picture! I can't decide if the monitors being huge
| feels stranger, or people wearing collard shirts.
| nerdponx wrote:
| I know this is maybe weird, but I kind of wish programmers
| and other "technical" people dressed up at least a little bit
| more for the office. It makes the work environment feel a bit
| tidier and more professional to me.
| surfsvammel wrote:
| I agree. But I'm old fashioned. I would never dream of
| going into the office without a collared shirt.
| groby_b wrote:
| Personally, I consider it a mark of professionalism if
| people aren't blinded by trivial external markers (like
| what clothes their colleagues wear)
|
| And I say that as somebody who _likes_ dressing up for
| work.
| Findecanor wrote:
| I think it is relative, and mostly a question of balance.
| Every workplace has its culture and norms.
|
| Making a little effort to blend in is a question about
| showing respect for your co-workers. But on the other
| hand, how you dress is self-expression.
| jacquesm wrote:
| If you're going to spend 8 hours per day with your butt
| in a chair facing a monitor you may as well dress for
| comfort rather than for looks.
| fsloth wrote:
| Precisely this.
|
| If you meet clients have a shirt. For daily coding, dress
| in what you like.
| nine_k wrote:
| I, as many of my colleagues, certainly dressed up for the
| office, carefully selecting only the most witty but
| understated T-shirts.
| WJW wrote:
| I've often wondered about dress code for programmers.
| From a quick poll conducted at lunchtime, we concluded
| that there definitely is a way to dress for acceptance
| among devs, it's just hoodies and witty T-shirts instead
| of suits and ties.
|
| Several people confirmed that they would probably be
| biased against applicants for dev positions coming in for
| an interview in a full on business suit with tie and
| slicked back hair (think "slick salesman" look). Perhaps
| not justified or fair, but interesting as a data point
| nonetheless. N=4 though, so don't take it too seriously.
| k__ wrote:
| I remember going to a meeting with fellow students I
| never met before.
|
| It was at a time I applied for jobs after university and
| so I thought, I might wear a collars shirt to the
| meeting, to get in the mood.
|
| All of my fellow CS students (aged 25-50) were wearing
| tshirts and generally more casual attire.
|
| The first thing I was asked: Oh, do you study management?
| fbanon wrote:
| Go ahead, dress up if that floats your boat. But don't
| force it on others!
| dekhn wrote:
| One of the funniest things I've ever seen was behind the
| scenes at TGIF at Google. Sundar was wearing some nice bay
| area gear (ie, ready to climb a mountain or meeting a
| corporate board room) and there were a couple PMs nearby
| wondering what brand he was wearing and how they could buy
| it.
| jacquesm wrote:
| I wished that people would stop focusing on exteriors so
| much and dealt with others based on merit rather than
| looks, age, height, weight.
| piker wrote:
| There is a notable difference between those
| characteristics and the sartorial. That will be left as
| an exercise for the reader.
| omnicognate wrote:
| Nobody said anything about looks, age, height or weight.
| jacquesm wrote:
| > "I wish people dressed up at least a little bit more
| for the office. It makes the work environment feel a bit
| tidier and more professional to me."
|
| That's very specifically about looks.
| omnicognate wrote:
| No, it's about what people wear.
| jacquesm wrote:
| Which is all about what they look like, really you're
| being pedantic beyond irritation.
| omnicognate wrote:
| The distinction, and its relevance, are obvious. If
| you're going to feign ignorance I have better things to
| do with my day than argue with you about it.
| jacquesm wrote:
| Then why do you argue about it?
|
| Yes, there is a distinction, no it is not relevant. Just
| like to a blind person it would not matter what you wore
| so therefore 'looks' and 'what you are wearing' are
| closely related, related enough to both be used in this
| context.
| regularfry wrote:
| "Everybody in this room is wearing a uniform. Don't kid
| yourself." - Frank Zappa
| alar44 wrote:
| It's not weird, it's controlling. Needing everyone to wear
| mono-colored shirts with buttons on it to feel tidy is a
| you problem.
|
| A company I worked for (that I did generally like working
| for) implemented a suit and tie policy for management and
| above. It didn't affect me but I started looking for the
| door immediately and left a few months after.
|
| Don't want to be in a company that is still clinging to
| 19th century values.
| shrimp_emoji wrote:
| But buttons, collars, ties, and other artefacts of 1500s
| tailoring technology have such respectability and
| gravitas!
| raxxorrax wrote:
| I always wear a collared shirt to work because I like
| them and they do look neat, but I cannot stand people
| that demand it from others.
|
| Hygiene is pretty important in the business I work since
| some of our devices come in contact with drinking water.
| But I can assure you that hygiene often does not
| correlate with outside appearances.
|
| Still, we have rules for people that have customer
| contact because people are still judgemental, even if
| they are often demonstrably wrong.
| iSnow wrote:
| To underscore, I would bet that washing hands frequently,
| wearing gloves when touching food and masks/hood when
| working near food is much more important than the
| difference between wearing a fresh white-collar shirt vs
| a sweat shirt you change every other day.
| raxxorrax wrote:
| That is vastly more important. It is mandatory to wash
| your hands before visiting production as well as changing
| clothes. Regardless of how clean they look, they will
| contain foreign matter. The cafeteria is pretty much
| declared a hazard zone, not only because of that one
| colleague who has a weird cheese experiment going on in
| the fridge.
|
| Downside for management is that we are only allowed to
| drink water in our offices and are not allowed to eat
| outside the cafeteria. With time I have grown to like it
| that way, even if I am a coffee junkie. But it never
| smells bad in the office in exchange.
|
| There is still some strange association with cleanliness
| and neat shirts.
| mensetmanusman wrote:
| It's not a 'you' problem per se, but just accepting that
| people are different, and that one size never fits all.
|
| Nice clothes have a reason to exist, determining where
| that fits in your life or your teams's life may be worth
| thinking about:)
| throwaways85989 wrote:
| The problem is, that alot of humanity still relies on
| cliches to communicate "base-truth". Suite and tie looks
| professional in movies, so you get more credit and
| respect for superficial looks on the job.
|
| One must not support such a ridiculous look based culture
| by heart, its instead more a - "I want to reap the
| benefits & rewards from idiots in awed reference to work
| uniforms"
|
| Ironically the same happened to the hoodie, after various
| hackermovies. Wear a hoodie and sit with a laptop,
| obviously improves your coding ability.
| ruined wrote:
| you can wear whatever you like in your home office. go
| ahead and dress up for yourself
| MathMonkeyMan wrote:
| Isn't this the plot of Spiderman 2? There the network used was
| Doc Ock's brain.
| equivocates wrote:
| Pretty sure this was the plot of Spider-Man 2 (Raimi Trilogy).
| vixen99 wrote:
| Chris Bishop and others were working on this with neural nets for
| the Tokamak at Harwell back in the 1980s which illustrates just
| how difficult this problem is.
| hamilyon2 wrote:
| No-no-no! Don't put machine learning and nuclear power together.
| Bad idea from all sides.
| willis936 wrote:
| Are you scared of a computer making a physically impossible
| chain reaction?
| pontifier wrote:
| cma wrote:
| Another interesting approach with some stuff on near fusion the
| end:
|
| Steve Brunton - Sparse Nonlinear Models for Fluid Dynamics with
| Machine Learning and Optimization
|
| https://www.youtube.com/watch?v=z_CZ_VyMDXE
| skyde wrote:
| oh dear god don't put Machine learning (a big unpredictable
| blackbox) in control of a safety critical process.
| klabb3 wrote:
| AFAIU this is entirely simulated - if it turns out the simulation
| doesn't perfectly match reality, what are the challenges in re-
| adjusting? Does the RL network need to be re-trained with massive
| amounts of data on a new improved simulation or can it be fine
| tuned on the real thing?
| kevinqi wrote:
| That's a great question; I'm curious about this as well.
| [deleted]
| starwind wrote:
| Probably massive amounts of data but it depends on how far off
| the simulation is from reality and the expected cost of
| collecting that data vs running the simulation a few billion
| times.
|
| Not far off and you want perfect results? Go with actual data.
| Very far off where it's not even usable? You'd need to go back
| to the training environment and redo the reward function.
|
| _Generally speaking_ (and I 'm not sure if this is the case
| from reading the link but I may have missed it) reinforcement
| learning for optimal control is done to fine tune while
| traditional control methods are used for coarse adjustments.
| Since this is deepmind they probably want to use RL for
| everything
| 317070 wrote:
| Hi, author here. We validated the neural network controller on
| the real plant in a couple of experiments. All experiments in
| the paper are based on data from running the controller on an
| actual tokamak.
|
| There is a video of one of these experiments in the linked
| blogpost (figure 2), where we show imagery taken from a camera
| looking into the vessel. Next to it is a reconstruction of the
| shot, visualised on a cross-section of the torus.
|
| The simulation not perfectly matching reality is indeed a major
| challenge, and the nature paper is mainly about showing how you
| can overcome that challenge. As others have said, plasma is a
| pain to model, and you cannot collect a ton of data on these
| machines. But it seems technology is coming at a point where we
| know how to work within these limits and still get it to work.
| exo-cortex wrote:
| Hi! this is fantastic article! Years ago I was able to visit
| the "Wendelstein 7X" stelarator-type fusion reactor in
| greifswald (Germany) when it was still assembled. It was so
| cool.
|
| Do you think this approach of controlling plasmas also
| translates to these types of reactors?
|
| Reading your article I didn't understand a lot of things and
| wondered if there was some kind of fusion-reactor-physics
| word-list where the most important keywords are explained a
| little. (without reading a whole book on plasma physics :-))
|
| Also the timescales are fascinating. How long is 200ms in a
| tokamak? How long does this reactor need to ignite or shut
| down the plasma?
| ali_m wrote:
| I think one of the challenges with stellarators is that
| they are harder to simulate due to the twisted geometry of
| the chamber (with a tokamak you can often simulate a single
| 2D slice of the torus).
| exo-cortex wrote:
| that makes a lot of sense.
| willis936 wrote:
| All optimized stellarator designs are periodic, so only
| one period (with correct boundary mapping) needs to be
| simulated. But yeah, it's a much larger search space.
| klabb3 wrote:
| Very cool, and thanks for replying to laymen comments such as
| mine.
|
| Do you think this line of research will eventually feed back
| into improved designs of electromagnets, chambers and so on?
| My limited understanding of the field is that the optimal
| reactor design is a moving target that's changed a lot over
| the years due to engineering improvements in manufacturing,
| material sciences and so on.
| 317070 wrote:
| Yeah, I think the main contribution of this paper in the
| long run, might be that the time is right for optimizing
| the controller together with the hardware?
|
| I'm imagining optimizing the plasma configuration, reactor
| shape, coil/sensor placement and controller all in one
| giant computational optimization. All the algorithmic
| components and models humanity needs to attempt this seem
| to be there.
| willis936 wrote:
| Well as long as there have been electronic computers they
| have been applied they have been applied to the problems
| of magnetic confinement. For tokamaks static
| configurations and dynamic controls have been simulated.
| For stellarators geometry optimizations have been done.
| The time has always been right for this application.
|
| Stellarators are particularly fun. First you optimize a
| last closed magnetic flux surface (a 3D sheet) with
| relatively simple plasma models, then you optimize coils
| (you need to weight things like magnetic field error,
| gaps big enough for heating and diagnostics, and coil
| complexity a la minimum radius), then you perform more
| accurate simulations to start the overall optimization
| loop again.
| ragebol wrote:
| There's a great episode of the Omega Tau podcast on this
| topic, not sure which one I mean from these though:
| http://omegataupodcast.net/tag/fusion/
| willis936 wrote:
| There are 4 episodes on fusion. You're probably
| referencing 312 which talks about simulating stellarator
| plasmas a bit.
|
| Episode 22 is an intro to fusion power research and
| tokamaks, but could be skipped if you are aware of the
| big concepts. Episode 157 is an interview of a director
| at ITER: the largest fusion power project in terms of
| scale, ambition, and funding. ITER is expected to
| demonstrate net energy gain fusion within the next ten
| years. Episode 157 gives a good sense of where the
| cutting edge of fusion power research exists currently
| and its potential place in society. Episode 304
| interviews the authors of a recent popular science book
| on tokamaks. This episode covers the history of fusion
| power research, and the economics involved in future
| power plants. Episode 312 is a set of interviews at W7-X:
| the current largest stellarator. This episode take a
| deeper dive into what fusion research is like and how
| threads are being tugged on.
|
| This same podcast also has interesting episodes on plasma
| physics and superconductors. The superconductor episode
| is especially worth listening to more than once.
| sanxiyn wrote:
| This was trained in simulation and then zero shot transferred
| to actual tokamak, namely https://en.wikipedia.org/wiki/Tokamak
| _a_configuration_variab.... All reported results are on actual
| tokamak.
| willis936 wrote:
| This is why fundamental plasma physics is so valuable to fund.
| ML can come up with good models that fit the data in the
| domains that there are empirical datasets to train against, but
| it can't reliably extrapolate outside of those domains.
|
| So this is a good tool for the computationalists but we still
| need the experimentalists. This is science.
| ShamelessC wrote:
| To clarify, this result did not have the benefit of a large
| labeled dataset. They used a simulator and got working
| results without _any_ finetuning on data measured from the
| real world.
|
| > So this is a good tool for the computationalists but we
| still need the experimentalists. This is science.
|
| I would say that this is a good example of collaboration
| between the groups.
| nicholast wrote:
| The root enabling factor was not only the reinforcement learning,
| it was the simulation. Put differently, any environment that you
| can simulate within sufficient accuracy, you can derive robust
| and efficient control by reinforcement learning.
| amelius wrote:
| You can do it without simulation, but you'd have to build a
| million tokamaks.
| willis936 wrote:
| Or one TCV.
| Sosh101 wrote:
| Is this really true with complex chaotic systems?
| PartiallyTyped wrote:
| If the reward function is sufficiently dense, then likely
| yes. RL uses function approximators to solve problems, so in
| theory the perturbations of the chaotic system shouldn't
| matter as much.
| avs733 wrote:
| I'm probably being excessively pedantic but I would suggest
| _sufficient fidelity_ is a more appropriate phrase than
| sufficient accuracy.
|
| The exact precision doesn't seem to be the underlying problem
| being solve, what matters is being able to craft a stronger
| understanding of relationships of underlying phenomena that can
| then be leveraged to product new control theories.
| adrianmonk wrote:
| I think they are just talking about how accurately the model
| reflects the real world.
|
| If someone draws a map and it has some streets with the wrong
| names, you say, "This map is not accurate." It doesn't mean
| you are talking about something numerical.
| agoose77 wrote:
| Right - in scientific parlance, accuracy and precision have
| distinct meanings: https://www.antarcticglaciers.org/wp-
| content/uploads/2013/11...
|
| In this case accuracy is appropriate :)
| chairmanwow1 wrote:
| I think this was an important distinction to make~
| EGreg wrote:
| How to simulate human humor responses? Then we can evolve AIs
| that are funnier and more resourceful than anyone on the
| planet.
|
| How to simulate human connection, attraction and arousal
| responses? Then we could have bots that are smoother talking
| and far more preferable to human lovers.
|
| How to simulate human responses to nutrition? Then we could
| have individualized recommendations for diets, achieving goals
| like holistic health or muscle definition and addressing issues
| like diabetes.
| ksubedi wrote:
| These are all complex systems where figuring out how to
| simulate them is a much difficult task than even reinventing
| reinforcement learning from scratch.
| elcomet wrote:
| That's not true of any environment though. You still need some
| characteristics like a not-too-sparse reward, and certainly
| many other things.
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