[HN Gopher] A robot will soon try to remove melted nuclear fuel ...
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A robot will soon try to remove melted nuclear fuel from Fukushima
reactor
Author : geox
Score : 90 points
Date : 2024-05-28 18:08 UTC (4 hours ago)
(HTM) web link (apnews.com)
(TXT) w3m dump (apnews.com)
| joe_the_user wrote:
| I think a problem that all the previous robots faced was the way
| that radiation interferes with the operation of any and all
| electronic devices.
| HeatrayEnjoyer wrote:
| Is there a barrier to powering it with mechanical energy
| instead of electronic? Gas combustion and hydraulics instead of
| batteries, CPUs, and servomotors.
| patmorgan23 wrote:
| And control it how?
| andrewflnr wrote:
| Fiber optic endoscope for the view, and manual mechanical
| controls. A big fat umbilical does reduce the mobility
| options a bit, granted, but it sounds/looks like they're
| already resigned to something along those lines with their
| '"telesco-style" extendable pipe robot'.
| HPsquared wrote:
| If they don't care about going slow, they could reduce
| the wire count massively using a relay multiplexer. One
| input/output at a time.
| pathartl wrote:
| I wonder if there's an issue with exhaust and radiation, like
| not wanting irradiated gas to escape into the atmosphere more
| than it already is.
| gibolt wrote:
| The brains are the issue, not the power source. If you
| operators can't see what is happening/control it, or the
| onboard autonomous mode glitches, you're gonna have a bad
| day.
| HPsquared wrote:
| Vacuum tubes and remote control.
| https://diakont.com/nuclear-services/radiation-tolerant-
| cctv...
| saalweachter wrote:
| Radiation affects cameras.
| misnome wrote:
| Maybe there might be radiation-hardened or tolerant
| cameras one could use?
| sandworm101 wrote:
| Endoscopes. A bundle of fiberoptic passively moves the
| image a few meters back to where a camera can run outside
| of the high radiation. Or even older-school, use
| mirrors/lenses/prisms as one would in a submarine's
| periscope to move the image far enough away.
| pfdietz wrote:
| The problem is that transparent materials are also
| rapidly degraded by radiation, ruining optics.
| distortionfield wrote:
| Did you even look at the link? Lol, they are selling
| specifically radiation hardened cameras for nuclear power
| plant use. I'm no nuclear engineer so I can't comment on
| durability but they are legitimately selling a solution
| to exactly that problem.
| blix wrote:
| Do you really think the engineers building a robot to go
| into Fukishima have never once looked at the first
| handful of google results for "radiation hardened
| camera"?
| Retric wrote:
| A more generous reading of that comment would be that
| it's other things not the camera's that are causing the
| problem.
|
| A CCD image sensor that's lost 20% of its pixels could
| still be providing useful information, especially if
| you're just trying to get the robot out. Other systems
| may inherently have issues long before that point.
| jcrawfordor wrote:
| Eh, I did some work with a team building a robot for
| maintenance inspections on an accelerator. Their client
| had come to the conclusion that the cost-benefit on
| radiation hardened cameras was questionable, and advised
| them to select inexpensive off-the-shelf cameras that
| could be regularly replaced in a cost effective way.
|
| Radiation hardening is tricky, there are tradeoffs
| involved and lots of reasons you might choose different
| points on the spectrum from "disposable robot" to "robot
| expected to have a long service life in a radiation
| environment."
| HPsquared wrote:
| I reckon a shutdown accelerator has orders of magnitude
| less radiation than a lump of Fukushima corium.
| bagels wrote:
| I think the other comments in response to this are
| because the text and the link don't seem congruent with
| one another. A radiation tolerant camera of that size is
| not likely to be using vacuum tubes.
| HPsquared wrote:
| Wikipedia page has a picture of a small one:
|
| https://en.wikipedia.org/wiki/Video_camera_tube
|
| They're probably really inefficient and need bright
| lighting, low resolution, etc etc. But that kind of thing
| won't get zapped by radiation. It's glass and metal,
| maybe a few phosphors.
| jjk166 wrote:
| These robots are radiation hardened, and the levels of
| radiation are steadily decreasing. At some point it will
| inevitably become survivable.
| johnea wrote:
| Exactly! we just need to try again in 10,000 years...
| BurningFrog wrote:
| I don't know the numbers, but it's much less!
|
| Because if an isotope emits high radiation, it will "burn
| out" relatively fast. If it lasts thousands of years, it
| does it by emitting low radiation.
|
| And, yes, I know this is a serious comment to sarcasm, but
| I feel educational today...
| lainga wrote:
| See the 7-10 rule (of murky and apparently empirical
| provenance), although this is for fission products of a
| bomb, not melted fuel
|
| https://physics.stackexchange.com/questions/336049/can-
| the-7...
| godelski wrote:
| > Because if an isotope emits high radiation, it will
| "burn out" relatively fast
|
| > but I feel educational today...
|
| To help people get intuition about this remember that
| energy is conserved. Radiation can come in multiple
| forms: alpha (2 protons and 2 neutrons), beta (electron
| or positron), or gamma (high energy "light"). At each
| decay even the original atom MUST lose energy, and thus,
| mass (thanks Einstein!).
|
| Alpha is pretty common (how Uranium-238 decays into
| Thorium-234, in 4.4e9 years, releasing 4.2 MeV of
| energy[0]). But also note that this is large and that's
| why it can be stopped pretty easily (unless the MeV is
| very high).
|
| Beta decay is a bit trickier because it can be either a
| positron or electron, but the process is quite similar.
| In both alpha and beta decay there's a clear mass being
| ejected from the atom (and along with it, energy). An
| example of beta decay is when Thorium-234 decays into
| Protactinium-234m (m for "metastable") in 24.1 days but
| with only 0.27MeV (you can tell here thought that this
| decay releases more energy over time, despite being a
| lower amount of energy released per decay event).
| Protactinium-234m then has a VERY short half-life of 1.16
| minutes releasing 2.27MeV per event, turning into
| Protactinium-234, which also has a short half-life of 6.7
| hrs, giving off 2.2 MeV of beta- (electron) decay,
| turning into Uranium-234, which has a long half-life of
| 2.45e5 years.
|
| I think this last example is where people get confused,
| because we went from Uranium to Uranium, right? But the
| numbers are important! Uranium-238 to Uranium-234! Those
| are the number of neutrons in each atom. Uranium-234 is
| much more stable.
|
| (I need to also note that there are some long lived
| products with high energies, but this is far more
| complicated than we have time for in this already long
| comment. We'd have to also discuss biological half-lives
| if we're going to talk about that. And someone will
| mention stuff about boars and mushrooms, and not
| understand)
|
| The other confusing part is waste and composition of
| waste[1]. It's important to note that 90% of waste is
| "low level", which are things like clothing or tools, and
| only contain 1% of the total radiation in waste. This
| stuff is readily disposed of, and the truth here is that
| were this to all get lost, there would be no real serious
| danger posed to any{one,thing}. We like to be on the safe
| side with nuclear, and for good reason (this is again,
| complicated). But the AMOUNT of waste is __VERY__ little
| > On average, the waste from a reactor supplying a
| person's electricity needs for a year would be about the
| size of a brick. Only 5 grams of this is high-level waste
| - about the same weight as a sheet of paper.
|
| And, > Unlike any other energy generating
| industry, the nuclear sector takes full responsibility
| for all of its waste.
|
| So this needs to be remembered when comparing competing
| energies. This is a common misconception when comparing
| and people without actual domain expertise here naively
| look at data and don't understand the assumptions of that
| data (I'm looking at us, HN...). And it is more
| complicated than just comparing the full waste generation
| from solar vs nuclear (as a far too common example. Which
| these technologies don't compete!)
|
| So TLDR:
|
| The decay can be simply thought of as "high energy, short
| lived" while the rest is actually incredibly complicated
| and exceptional levels of nuance are required for
| actually making good comparisons. This last part isn't
| isolated to nuclear technologies and is a common logic
| failure of many internet warriors.
|
| TTLDR: shit is complicated, don't talk about complicated
| stuff if you're passion doesn't align with your efforts
| to educate yourself and understand the nuance.
|
| [0]
| https://en.wikipedia.org/wiki/Decay_chain#Uranium_series
|
| [1] https://world-nuclear.org/nuclear-essentials/what-is-
| nuclear...
| jrflowers wrote:
| I like this comment because it can be summed up as "You
| are pretty much correct, also I am smarter than you are"
| godelski wrote:
| Definitely not. I have no idea how much BurningFrog knows
| or not. I was just continuing their education. Expanding
| on their comment, no more.
|
| Don't always assume malicious behavior. We're nerds.
| Sometimes we just get excited to talk about things we've
| sunken thousands of hours of our lives learning and get
| excited thinking others might also be excited with this
| thing we find cool.
|
| I hope there are things you get a lot of joy thinking
| about and when given the chance to talk about. I for one
| always enjoy hearing people talk about their passions (I
| just hope that passion aligns with dedication).
| elzbardico wrote:
| Correct me if I am mistaken, but I always had the
| impression that the storage requirements for nuclear
| waste are a lot bigger than what they needed to be,
| because there's kind of a taboo against widespread
| processing this waste because this would provide a lot of
| weapon grade plutonium.
| toomuchtodo wrote:
| https://www.science.org/content/article/lasers-defuse-
| nuclea... ("Lasers Defuse Nuclear Waste")
| pfdietz wrote:
| Also, because fission products are weirdly broken into
| two groups: those with relatively short half lives, and
| seven ones with very long halflives.
|
| The first group is essentially gone after several
| centuries. The second group has half lives in the
| hundreds of thousands to millions of years. There is an
| absence of significant fission product radioactivity in
| the intermediate range of half lives.
|
| There are also _actinides_ with half lives in that range
| (like, various plutonium isotopes).
| HPsquared wrote:
| Vacuum tubes are pretty radiation-proof. It depends how
| primitive you want to get with the electronics.
| guerrilla wrote:
| Vacuum tubes are generally big, high voltage and require
| large power supplies; so pretty terrible for robots.
| dylan604 wrote:
| Not if you're building Mechzilla. There's plenty of room
| for them at that scale!!!
| _carbyau_ wrote:
| One of the quirks I love about Battletech. A targeting
| computer weight is measured in tons... It really is a
| game of stompy robots as the 1960s thought they could be.
| pjc50 wrote:
| Obviously you solve this by using nuclear power for the
| robot. /s
| HPsquared wrote:
| Power supply etc would be external. They would have
| absolutely minimal electronics onboard, I was referring
| specifically to camera tubes:
|
| https://en.wikipedia.org/wiki/Video_camera_tube
| magicalhippo wrote:
| [delayed]
| acchow wrote:
| You could have the "brains" of the robot sit outside of the
| actual physical robot connected by very long wires.
| ceejayoz wrote:
| They do that already. https://www.cbc.ca/radio/quirks/one-
| minute-of-exercise-fukus...
|
| > But so far, at least seven have broken down in there
| while trying to locate radioactive fuel, including two that
| just died in the last few weeks. One was pulled back after
| just two hours of a ten hour mission. Radiation had fried
| its camera. Another had to have its remote control cable
| snipped when it encountered something it couldn't get
| around.
| exe34 wrote:
| I wonder if they could do something with just lenses and
| optical cables, and have the ccd or even just a dark room
| far away next to the electronics.
| ggm wrote:
| Begs questions if prolonged irradiation causes cloudiness
| in fibre optic cables or breakdown of the sheath.
| Radiation speeds up mechanical stress cracks materials
| doesn't it?
|
| Energy does what energy does.
| strangattractor wrote:
| The Russians developed a way to deal with this at Chernobyl -
| send in people. They also use this method to deal with bullets
| and artillery in Ukraine.
| moffkalast wrote:
| When all you have is people, all problems look like they need
| some people thrown at them.
| ESTheComposer wrote:
| Reminds me of this story by Isaac Asimov
|
| https://en.wikipedia.org/wiki/Runaround_(story)
| ErkanSensei wrote:
| Reminds me of this story by Isaac Asimov
|
| https://en.wikipedia.org/wiki/Runaround_(story)
| netcraft wrote:
| > TEPCO plans to remove less than 3 grams (0.1 ounce) of debris
| in the test at the Fukushima plant.
|
| ...
|
| > About 880 tons of highly radioactive melted nuclear fuel remain
| inside the three damaged reactors
|
| talk about starting small
| fbdab103 wrote:
| Given the damage is already done, why not leave it in place?
| Encase it in concrete and come back in a decade or two when the
| worst products have decayed?
| loeg wrote:
| > an extremely important step to steadily carry out future
| decommissioning work
|
| > Better understanding the melted fuel debris from inside the
| reactors is key to their decommissioning
|
| It's not exactly clear to me how this benefits decommissioning
| either, but that's all I got from the article.
| Retric wrote:
| People can't safely work near the fuel(high level nuclear
| waste) because it's really radioactive. They can work where
| high level nuclear waste (fuel) used to be.
| lazide wrote:
| Also, if they don't know exactly how thoroughly it melted
| or the precise level of damage, it's pretty hard to fix it.
|
| It isn't the type of problem amenable to just bulldozing it
| into a hole, unless you're Russian anyway.
| dylan604 wrote:
| Fix it? Do you mean the design? Because there's not
| fixing this one.
|
| It seems to me the fix would be to not have your backup
| generators below the water line.
| loeg wrote:
| Yeah but why have people there at all? Upthread commenter
| is asking about just filling it with concrete and leaving
| it alone.
| Retric wrote:
| They need to freeze the ground to avoid water flowing
| into and out of the area. Covering in concrete alone
| wouldn't safely contain it, they would need to add
| concrete beneath the fuel, which while physically
| possible would be unbelievably expensive and not actually
| last that long. Eventually tossing future generations an
| even more expensive problem.
|
| https://www.tepco.co.jp/en/decommision/planaction/landwar
| dwa....
| loeg wrote:
| Thanks.
| robertlagrant wrote:
| The article mentions a 30-40 year cleanup target; perhaps
| they're using these samples to analyse how best to proceed?
| Retric wrote:
| It's contained, not stable. They are doing a bunch of things
| like freezing the ground to avoid water intrusion which have
| high ongoing costs.
|
| Remove high level waste to a more stable environment is the
| first step in reducing those ongoing costs.
| surfingdino wrote:
| It may not be that simple. Scientists want to know what's going
| on down there. As Chernobyl shows us, we don't really know when
| it's over https://www.extremetech.com/extreme/322755-chernobyl-
| is-heat...
| odyssey7 wrote:
| > Critics say the 30- to 40-year cleanup target set by the
| government and TEPCO for Fukushima Daiichi is overly optimistic.
|
| Wow. By the time they finish the cleanup, we could be running
| profitable fusion power plants, have humans living on mars,
| discovered new physics...
| jvanderbot wrote:
| _Could_.
|
| More likely we'll be debating the usefulness of yet another
| fusion plant over some hydrothermal project vs some tidal
| energy project vs UBI expansions and on and on.
| realusername wrote:
| I have a feeling it sounds like those flying cars of the 2000s
| and none of that might come up.
| pjc50 wrote:
| By then, we might have built one or two regular fission
| reactors.
| nijuashi wrote:
| Crane game player: "my time has come"
| rassimmoc wrote:
| figures.... robots and AI keep stealing our jobs and politicians
| not doing anything about it
| ramon156 wrote:
| When I was growing up I was dreaming of exploring in the
| radiation, thanks Biden.
| rassimmoc wrote:
| thats how real men did it in chernobyl
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