Is there a barrier to powering it with mechanical energy instead of electronic? Gas combustion and hydraulics instead of batteries, CPUs, and servomotors.
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'.
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.
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.
Would having two robots make a difference? One without sensors for close encounter with the radioactive material and another for with sensors that observes from distance?
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.
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"?
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.
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."
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.
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.
Yeah I guess it could interfere with the image, but that's solved by turning down the gain (or using a less sensitive tube etc) and using brighter lights.
> 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.
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).
I thought about getting a little bit deeper into the details, but decided to keep it brief. `godelski`s comment expands on the theme for anyone interested.
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.
> I always had the impression that the storage requirements for nuclear waste are a lot bigger than what they needed to be
This is debatable and I don't like to -- especially in a public setting -- give an authoritative answer of "yes" or "no" because truth is that neither of these would be correct.
I'd rather state some of the factors involved and give you the idea that this is complicated and that there are very smart people working on these issues and we have good reason to trust them (rather than trying to reason through the problem entirely by ourselves[0]).
So the question about nuclear safety is not a binary one, and truthfully this is true for any question about safety (or most things!). Instead it is about level of acceptable risk. This can be VERY small and to the point where we just treat it as a binary case (but it isn't!) or certain bounds. This type of risk assessment is quite complex, especially with nuclear, and depends of the __type__ of failure. So this also includes a whole other topic of failure design/engineering (e.g. skyscrapers are __designed__ to collapse in on themselves. Not to make them weaker or to cause them to fail, but to control the way that they fail __if__ they fail. You don't want your building falling over and taking out another building (creating a cascading effect), so if it falls in on itself it is less likely to cause more damage. Bridges are another common example if you want to learn more).
Nuclear safety design is quite complex because of all the ways things can go wrong and our great concern for safety (making this a WELL studied topic and why the nuclear industry is one of the safest, and arguably the safest in terms of power generation. Even including the 3 main disasters). Disasters are complex and I'll bet you most of what you've heard about Chernobyl, Fukushima, and 3 Mile are quite limited in accuracy. This isn't because of dishonesty or malintent, but because of the complexity.
So the big questions about nuclear storage is how long we want to have a high confidence in our storage. Certainly we have a large and abnormal margin of safety in nuclear compared to other industries, but the question is if we want this or not (that's not a question that science answers, that's a public policy question and to answer appropriately we need to be aware of our answers to this question for other comparable industries (which means not assuming or "reasoning your way through it." It means spending time)) There are some people who want the high level waste to be safely stored for tens of thousands of years and under strong conditions such as not necessarily understanding English or our conventional warning signs (there's a whole rabbit hole to go down here![1]). But there are others who think it is fine to have a safety solution that is good for several hundred years and that we should use this as we invent better techniques. With this, we actually have the technology and even use it today. This route would allow us to store waste on site and there's discussion of ways to cheaply and effectively decommission plants ontop of themselves. (FWIW, this is the option I'm in favor of) Part of the reason some want this method is because it's extremely reasonable to believe that we actually want this material and as our technology has advanced in the last 70 years, we've learned how to extract much more energy from our fuel (which means much lower waste products, which means lower length of half-lives on material, which also means we can recycle old fuel and turn it into new fuel. To understand this properly we need to understand how the fuel actually works, but this is another long topic. I'll just say that we use a very small portion of it. And I'll also mention that France gets about 17% of its total electricity from recycled nuclear. Not 17% of nuclear energy, 17% of __total__ electricity[2]).
The last thing I want to say is we have to keep in mind how much mat...
I wish I could vote for people like you on the elections. It would be a far better world to have representatives that understand the issues, and understand what we still don't know for certain about those issues.
Thanks, but I don't want to be a politician. I would encourage you to look into Star and approval voting though. Cardinal methods are pretty powerful considering you can embed candidates with an inhomogeneous metric. Not to mention you're rating then independently instead of against one another. Ordinal methods have gotten quite popular but still have these fundamental flaws.
I'd encourage fixing the voting system so people that do want to be politicians and have expertise can actually have a chance. Instead of resulting in extremist points of views
I literally copied these numbers from the provided link. Because I never remember this stuff off the top of my head, even when I was working in nuclear.
But sanity checking, we find the same chart on the EPA's website[0] as well as the IAEA's site, which you can then calculate the chain yourself pretty easily (down 2 + left 2 (alpha), diag up left (beta-), diag up left (beta-)).
Maybe you're thinking of U-235, which has a half-life of 7e8yrs? Or U-233 with 1.6e5yrs? These aren't considered stable btw.
>>>> godelski:
>>>> how Uranium-238 decays into Thorium-234, in 4.4e9 years,
>>>> Uranium-234, which has a long half-life of 2.45e5 years
>>> jojobas:
>>> You got something terribly wrong
> jojobas:
> From the provided link:
> U-238 4.468×10^9 a
> U-234 2.45×10^5 a
I've been checking for a typo, so that's why I quoted, but I'm not seeing it. Can you clarity? It looks like you used the same numbers as I did.
Is the confusion "a"? It stands for annum. Which in the decay chart on the EPA site (at the bottom) there's a nifty legend that specifies "half-life units: a - years". But the IAEA site specifically uses "y", stating "4.468 x 10^9 y" and "2.455 x 10^5 y".
Are you mad at the rounding? I'm really trying to understand what you're saying I've said is in error. If I made an error I'd like to fix it.
I think the correspondent takes issue with the 4th paragraph in your post describing alpha and beta decay; specifically your calling U-234 "much more stable" than U-238. I don't know if "more stable"/"less radioactive" denotes a slower rate of decay, less energy released, or is based on some other metric, but the perceived error seems to hinge on the half-life of U-234 precluding it from being considered "more stable" than the much longer-lived U-238.
As I don't know if that's what a degree of stability in an isotope would refer to I don't take a position, but simply offer a hopefully less confused reading of the exchange y'all are having. I enjoyed reading your posts and found them very approachable.
Oofff, yeah, that was a mistake. Thank you for clarifying. I really wasn't getting what the other user was trying to communicate, but it does make sense now. I was having a hard time seeing it because I was like "yes, that's correct?" not seeing where the actual blunder on my part was lol.
Yes, U-238 is more stable than U-234. I incorrectly wrote the reverse before.
Degree of stability would refer to the rate of decay, which generally is going to strongly correspond to the half-life. (I think the error happened in an edit, where I was previously still talking about Pa. Either way, I messed up)
Why is it waste? Putting it into breeder reactors is one thing, but we've got this stuff, thats emitting dangerous nuclear radiation, but isn't that radiation energy? What would it take to harness that energy and turn it into a power source?
The juice isn't worth the squeeze. Whatever you build to harness that energy would be very expensive compared to the relatively small amount of power you get out of it.
I kinda explain this in the other post, but this is a good question.
For the low and intermediate level waste, these probably aren't useful amounts of radiation. Even if you could 100% turn all that energy into electricity. It just wouldn't be that much (the amount to harm your body is actually not that much total energy, because cascading effects. Again, complicated, because type of radiation and where it is plays a significant role (dominating even)).
But for the high energy waste, yes! In fact, France even does this (ironically the US invented the technology). 17% of their total electricity comes from recycled fuel. This is partially why I'm in favor of in situ storage.
But this does get quite complicated. As I've, and others, said, if something is long lasting it probably isn't giving off much radiation. Though, these isotopes typically can be converted into an isotope that will be shorter lived and produce higher energy (in fact, this is part of the whole theory behind nuclear power). In fact, even all that fuel from France that is "spent" is still pretty energetic.
But I should finish by referencing this graph[0]. The differential in y is energy and so you gain energy (electricity) going right to left if you're an element heavier than lead (fission) or left to right if you're lighter (fusion). While the slope is relatively steady, at a certain point it becomes not worth it.
So really there's a lot to consider here but we would need to invent quite a lot of things along the way. Which, is very viable in the next few hundred years (which is how long we believe we can safely store fuel on site).
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).
The importance of the "several centuries" is that it sets an upper limit on how long we can wait before reprocessing or burying (or otherwise permanently disposing of) spent nuclear fuel. After that point, the fuel's gamma activity will have declined so much it is no longer self-protecting from "amateur" reprocessing and diversion of the plutonium.
I think it's quite plausible that today's dry casks could last several centuries. So, we have a technology that will last as long as it could be intended to. Arguably it's better for our descendants to do this and let them deal with the waste, not needlessly do something much more expensive. Our descendants will not like that we squandered wealth and left them with larger debts or lower growth either. Always consider what else could be done with resources when you advocate their use.
In a similar "sometimes our intuition is wrong" vein, we often learn about types of radiation that are hard to shield against, which makes them automatically scarier than ones "stopped by a sheet of paper."
However in some circumstances those types are actually safer to be around, since radiation that can't be stopped is also radiation that isn't interacting and dealing damage.
________________
This relates to the radioactive cookie puzzle, which has many variations, ex: "You have three cookies that emit alpha, beta, and gamma radiation respectively. Choose one cookie to eat, one to put in your pocket, and one to put in a thin lead box."
(Partial spoiler) Put the alpha-emitter in your pocket, since it'll be blocked by a layer of fabric and dead skin cells. (Your eyes remain vulnerable, though.) The lead-box would be overkill. Finally, even if it seems easy to manage, the alpha-radiation is not safe: Eating that cookie could kill you, since your important (living) inner cells would be damaged trapping its output.
Conversely, eating the gamma-ray emitter is sometimes the best call, because it's not going to be much worse than the other choices, and much of it will leave your body unimpeded.
This may seem counter-intuitive, but the longer the half-life of a given radioisotope, the less radioactive it actually is. In a given pile of nuclear waste, the scariest stuff is also the first stuff to decay into something stable. It's why waste from power plants only needs to rest in the cooling pool for a few years before it is safe enough to transport to a long term storage facility.
I don't feel it's counterintuitive. If we have a leaky cauldron, the bigger the hole, the faster it emptied and vice versa. Although we wouldn't know whether this big stream is because of a big hole or a big jug...
As an example: there is a very long lived radioisotope of iodine that occurs in fission products, iodine-129, with a half life of 15 million years.
The radioactivity of this isotope is so low that, as I understand it, one could replace every iodine atom in your body with this isotope and you'd still be okay. This would imply it's fine to dispose of this isotope by just dissolving it into the ocean. The ocean's total iodine is about 10^11 tons, so a disposal rate of ~10^4 tons/year would eventually (in ~a half life) make the ocean's iodine mostly I-129 (conservatively, assuming no exchange of iodine is occurring between the ocean and external reservoirs of the element.) This production rate is what would obtain in a totally nuclear powered world at today's primary energy consumption rate.
With Uranium half-life of 4.5b years and current exposure of tens of thousands roentgens per hour, the roadmap to survivability extends well beyond the heat death of the universe, though.
Uranium isn't the issue. A long half-life means that it's only mildly radioactive. Prior to being irradiated in a reactor, fuel rods can be manually handled safely. The majority of radiation being emitted currently is coming from fission products like Sr-90 and Cs-137 that have half-lives of decades.
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.
The MiG-25 used nuvistors[1] for the avionics, which are quite small compared to your average stereo amplifier tubes. Sure it requires high voltage, though "only" around 100V[2].
> 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.
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?
Essentially, they use optical fiber as radiation sensors on Fukushima. So, while the concern about cloudiness is valid, the reality is that at least some types of optical fibers work okay even there.
Yea I have two things on my 50 years bingo chart: supporting unemployable people through UBI/bullshit jobs by reallocating the profits from automated production, or getting rid of them through wars, famine, etc. until only the capital owners remain.
Still waiting on which one it'll be. Probably both to some extent.
the only idea I have on how to improve the outcome here is normalizing things like Gofundme and Patreon and just in general transferring wealth from people who hit the automation jackpot to people who don't.
But things are going to get weird and it's hard to predict the social consequences. Maybe robots get so cheap that there's no reason the have-nots don't have them, too (like today with smartphones and cars) and then there's no famine because food production is so easy with automation (???)
It will continue until either Putin is no longer in power, or until RU is pushed back to its borders. Russia implements Lenin's approach: "We probe with bayonets, where we find mush, we press on, where we find steel,we withdraw.". The West has so far provided mostly mush and insufficient & overly constrained steel (e.g., short range and can't hit targets in RU so self-creating a safe zone for Putin). When the West steps up to win, it will end. If it doesn't, we'll be fighting more expensive wars on NATO territory, the Baltics, Poland, Finland, and more.
Maybe they deleted their old comments? Maybe some weird bot? I'm mostly frustrated that I flagged it and someone vouched the comment despite it being an obvious dupe from a sketchy account.
People do actually generate and not use HN accounts and then later sell them on or give them some life (repeating other comments in days old threads is common) so they can later be used to "chime in entusiastically" when a product is launched.
Watch that account and see if it endorse | votes up a submission next week.
I couldn't find fuel weight in a BWR-3, but a RBMK reactor (Chernobyl) contains between 150 and 200 tons of Uranium.
Now, a RBMK runs natural uranium, so you're going to be using more fuel for the same power, but it suggests the number isn't totally whack.
I would not be surprised by it being a typo, but depending on what you include in "melted fuel" (fuel assembly, reactor parts, etc), 880 tons isn't outrageously high either.
Well, ~75 tons of fuel per three units fully loaded plus a few times that for the spent nuclear fuel pools. Also bear in mind that fuel being melted with concrete and metal becomes one, so you can add a hefty multiplier to the above figure. So it seems like 800 tons is in the ballpark of the fuel assemblies plus molten metal structures of the lower part of the reactors vessels.
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?
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.
No, the fix is to not have fucking politicians in charge of practical matters.
Yes, I'm serious. TEPCO wanted to dump sea water into the reactors as a last resort so they wouldn't melt down, but the Japanese government at the time didn't allow it because the reactors would be rendered unusable.
Of course, the reactors melted down and became unusable anyway.
Fukushima #1 was a human failure and the only solution to that is a human solution. Any engineering solution will be foiled by a bigger human failure, as the saying goes.
I mean sure, but if the backup generators weren't submerged from failure to plan for flooding, then the politicians wouldn't be in that situation. That's an engineering solution that isn't like earth shattering. Maybe it was a human bean counter that said it would cost too much (ha!) to do that for the generators. This isn't the same situation of planning to use school buses as an evacuation plan not realizing their parking lot is likely to be flooded. This is a nuclear reactor and there's meant to be some really smart people involved.
>if the backup generators weren't submerged from failure to plan for flooding
We need to be fair here: Plans for potential flooding were made, the issue was nobody expected a tsunami that fucking tall and reasonably so.
Guidelines and such have been updated since so it (hopefully) won't happen again, but you can't fault engineers of the past for working with the data they had and coming to the conclusions they did.
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.
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.
Indeed, yes, nothing is certain... The other part, which is about certain, is that we'll have been dealing with the fallout of this particular meltdown for 30 to 40 years, or more.
The third part that is also about certain is that we'll be dealing with climate change, since we are not stopping burning fossil fuels. Instead we are building new fresh power plants fueled by fossil fuels with planned operational life times far into the future.
I guess in listing other milestones, I might have alluded to an ongoing debate? Whether to build new fission reactors or to wait for new fusion tech? My intention was only to indicate the scale of the harm in this particular instance.
However, it’s still tempting for me to respond to this fission-prevents-global-warming claim with my own appraisal. You’re right, it is certain that we’ll still be using fossil fuels. I’ve given up worrying about fossil fuels and global warming. It’s something I can’t do anything about, and I think it will be fine: the people who make the macro decisions decided decades ago that we didn't really need to / weren’t going to risk economic growth by suddenly reducing fossil fuel use as much as the scientists said would be needed. It was really a masterwork: the same political groups eager to go to war in the Middle East and hungry for tax breaks were kept more than eager to keep buying gas, effectively sending their money to the Middle East about once or more a week in many cases. There are some nuances that undermine the reasoning expressed in my last sentence, but I’m sure that those particular nuances weren’t the justification, as much of the public has indicated that they support bombing even Agrabah. [0]
Why didn’t we do enough? Well, lately it has turned out that geo-engineering was taboo only to indicate as an option, not to actually do when the time came. [1] It looks like the plan all along has been geo-engineering, while keeping the public on-edge about that to justify projects like fission plants. Fission research has long been an avenue to develop knowledge essential for nuclear weapons R&D. In the context of international relations and international nuclear treaties, the cover story of saving the planet makes even more sense as an essential. The Secretary of Energy was in Congress just the other day discussing compensation for victims of Manhattan Project radiation [2], a topic which has nothing to do with nuclear energy, unless nuclear energy is sometimes a codeword for nuclear weapons. Fission isn’t really important to stop global warming if we’re just going to implement geo-engineering.
It is less that fission-prevents-global-warming, but that removal of nuclear plants has a very strong positive relationship with the construction of new fossil fueled power plants. Sweden as an example did not use fossil fueled power plants, but in the aftermath of decommissioning of their most southern power plant there is now one oil fueled power plants operating almost 24/7, and a additional new gas powered plant being building built. This in times where emissions need to go down rather than up. Its also a fairly common story in other countries where nuclear power plants get decommissioned and hastily get replaced with newly constructed fossil fueled power plants.
Sweden did have a nuclear program but it was decommissioned in 1966. The program instead went exclusively into civilian energy production, with nuclear power plants being built from 1969 until 1980. The military did not show any interest since 1970, with nuclear weapons deemed way to expensive, ineffective, and the civilian research and military research diverging too much in order for continued cooperation.
Geo-engineering is interesting, but like nuclear weapons it is also a tool for mass destruction and warfare on a scale that even dwarf the largest nuclear weapons in existence. The R&D for geo-engineering in order to address global warming is indistinguishable from using it as a weapon. It order to make sure that geo-engineering does not cause mass destruction, it is essential to know what could trigger mass destruction.
We might have one or two prototype fusion plants, in the most optimistic plans that are not pure marketing fluff. We might have a small research base on Mars where one or two people occasionally spend a few months or something.
Two days too late to comment this. Think about how many people could be employed. It would be a lot too because they could only work for 45 seconds each.
But why would you become anti-nuclear energy because of this? The cleanup is obviously professionally handled and it doesn't appear to be an issue for nature and nearby population.
Technically impressive, but unfortunately feels basically like a PR stunt.
The title suggests that the melted material will be removed soon but is not realistic. At this moment should say "will try to remove 3 grams from the >800 tons of melted fuel. At this pace, the place will be safe by natural means much before the robot will end the work.
Apart of this, I wonder... is this stuff still usable? There is something that could be done with this grams of melted dust that would worth the risk of spreading it around?
...
Second: why to design a robot for that, or move electronics close to this area so they can fry in seconds?.
The idea that must be some sort of robot (because some sort of idealized human rescuer figure is what the public expects) is not very smart. What they need is maybe (IMAO) a sort of "anteater-tongue machine" that just will try each crevice until finding the correct path. A sort of strictly mechanical machine moved from a safe distance with a real human brain taking the decisions much faster.
If you need to move a tube there are a lot of solid mechanical joints in the market tested since decades for every possible need. All needed is an axis able to rotate, a motor placed very far away, and a removable set of arms that would pick and vacuum the stuff and would double as "fuel rods" or something later when will be unavoidably contaminated. Just cut the tube in appropriate lengths and put the contaminated rod to sleep in the pool with the other stuff.
If electronics are an obstacle, just remove it entirely and use a stochastical movement instead a directed one.
Radioactive dust in the path could be grabbed with some type of greasy or sticky material before to be collected by a moving ring. No need to design a complicated claw here. There are several metallic types of grease available that could jail the dust and maybe even, dunno, provide benefits to block the dust radiation somehow into a matrix of metallic particles.
If you need to see the path, use echolocation or maybe run a camera forward for one second to retreat it fast to safety. The "tongue" could be used as a rail for the camera.
Alternatively, they could made the path safer first deploying a lead jacket made with tubes or plates where the robot can move. If the room is radioactive, line it in lead lames. That would also remove coins and crevices and would made the route much safer for people and machines and easier to navigate until the final part.
I was at Fukushima Daiichi on Monday, and they explained that they only want to take a few grams of the melted material to test the composition of the melted fuel/debris, e.g. what elements are in it.
Even just planning to remove all of the melted fuel is a long way away.
I can't remember if they were talking about Unit 1 or Unit 2, but from what I understood is that due the collapsed rubble above/around the reactor, they only have a very narrow opening, which means they've struggled to use larger robots.
And I believe the robot operating centre is a bit of a distance away from the reactors too (probably so that the robot operators don't need to wear protective equipment).
> What they need is a sort of "anteater-tongue machine" that just will try each crevice until finding the correct path.
I think the problem is that once you get through all the debris, there's a big cavern. Hence why they're using some sort of crane robot on a rope (it reminds me a bit of a [claw machine game][1]).
141 comments
[ 6.1 ms ] story [ 209 ms ] threadA 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.
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."
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.
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...
https://physics.stackexchange.com/questions/336049/can-the-7...
> 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
And, 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_...
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).
>This last part isn't isolated to nuclear technologies and is a common logic failure of many internet warriors.
I thought about getting a little bit deeper into the details, but decided to keep it brief. `godelski`s comment expands on the theme for anyone interested.
And all is well!
This is debatable and I don't like to -- especially in a public setting -- give an authoritative answer of "yes" or "no" because truth is that neither of these would be correct.
I'd rather state some of the factors involved and give you the idea that this is complicated and that there are very smart people working on these issues and we have good reason to trust them (rather than trying to reason through the problem entirely by ourselves[0]).
So the question about nuclear safety is not a binary one, and truthfully this is true for any question about safety (or most things!). Instead it is about level of acceptable risk. This can be VERY small and to the point where we just treat it as a binary case (but it isn't!) or certain bounds. This type of risk assessment is quite complex, especially with nuclear, and depends of the __type__ of failure. So this also includes a whole other topic of failure design/engineering (e.g. skyscrapers are __designed__ to collapse in on themselves. Not to make them weaker or to cause them to fail, but to control the way that they fail __if__ they fail. You don't want your building falling over and taking out another building (creating a cascading effect), so if it falls in on itself it is less likely to cause more damage. Bridges are another common example if you want to learn more).
Nuclear safety design is quite complex because of all the ways things can go wrong and our great concern for safety (making this a WELL studied topic and why the nuclear industry is one of the safest, and arguably the safest in terms of power generation. Even including the 3 main disasters). Disasters are complex and I'll bet you most of what you've heard about Chernobyl, Fukushima, and 3 Mile are quite limited in accuracy. This isn't because of dishonesty or malintent, but because of the complexity.
So the big questions about nuclear storage is how long we want to have a high confidence in our storage. Certainly we have a large and abnormal margin of safety in nuclear compared to other industries, but the question is if we want this or not (that's not a question that science answers, that's a public policy question and to answer appropriately we need to be aware of our answers to this question for other comparable industries (which means not assuming or "reasoning your way through it." It means spending time)) There are some people who want the high level waste to be safely stored for tens of thousands of years and under strong conditions such as not necessarily understanding English or our conventional warning signs (there's a whole rabbit hole to go down here![1]). But there are others who think it is fine to have a safety solution that is good for several hundred years and that we should use this as we invent better techniques. With this, we actually have the technology and even use it today. This route would allow us to store waste on site and there's discussion of ways to cheaply and effectively decommission plants ontop of themselves. (FWIW, this is the option I'm in favor of) Part of the reason some want this method is because it's extremely reasonable to believe that we actually want this material and as our technology has advanced in the last 70 years, we've learned how to extract much more energy from our fuel (which means much lower waste products, which means lower length of half-lives on material, which also means we can recycle old fuel and turn it into new fuel. To understand this properly we need to understand how the fuel actually works, but this is another long topic. I'll just say that we use a very small portion of it. And I'll also mention that France gets about 17% of its total electricity from recycled nuclear. Not 17% of nuclear energy, 17% of __total__ electricity[2]).
The last thing I want to say is we have to keep in mind how much mat...
I'd encourage fixing the voting system so people that do want to be politicians and have expertise can actually have a chance. Instead of resulting in extremist points of views
You don't get to anything more stable in the U-238 decay chain until you reach Pb-206, which is stable.
But sanity checking, we find the same chart on the EPA's website[0] as well as the IAEA's site, which you can then calculate the chain yourself pretty easily (down 2 + left 2 (alpha), diag up left (beta-), diag up left (beta-)).
Maybe you're thinking of U-235, which has a half-life of 7e8yrs? Or U-233 with 1.6e5yrs? These aren't considered stable btw.
[0] https://www.epa.gov/radiation/radioactive-decay
[1] https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
U-238 4.468×10^9 a
U-234 2.45×10^5 a
Is the confusion "a"? It stands for annum. Which in the decay chart on the EPA site (at the bottom) there's a nifty legend that specifies "half-life units: a - years". But the IAEA site specifically uses "y", stating "4.468 x 10^9 y" and "2.455 x 10^5 y".
Are you mad at the rounding? I'm really trying to understand what you're saying I've said is in error. If I made an error I'd like to fix it.
As I don't know if that's what a degree of stability in an isotope would refer to I don't take a position, but simply offer a hopefully less confused reading of the exchange y'all are having. I enjoyed reading your posts and found them very approachable.
Yes, U-238 is more stable than U-234. I incorrectly wrote the reverse before.
Degree of stability would refer to the rate of decay, which generally is going to strongly correspond to the half-life. (I think the error happened in an edit, where I was previously still talking about Pa. Either way, I messed up)
If I need to touch grass, why don't you join me, because clearly I'm not alone.
For the low and intermediate level waste, these probably aren't useful amounts of radiation. Even if you could 100% turn all that energy into electricity. It just wouldn't be that much (the amount to harm your body is actually not that much total energy, because cascading effects. Again, complicated, because type of radiation and where it is plays a significant role (dominating even)).
But for the high energy waste, yes! In fact, France even does this (ironically the US invented the technology). 17% of their total electricity comes from recycled fuel. This is partially why I'm in favor of in situ storage.
But this does get quite complicated. As I've, and others, said, if something is long lasting it probably isn't giving off much radiation. Though, these isotopes typically can be converted into an isotope that will be shorter lived and produce higher energy (in fact, this is part of the whole theory behind nuclear power). In fact, even all that fuel from France that is "spent" is still pretty energetic.
But I should finish by referencing this graph[0]. The differential in y is energy and so you gain energy (electricity) going right to left if you're an element heavier than lead (fission) or left to right if you're lighter (fusion). While the slope is relatively steady, at a certain point it becomes not worth it.
So really there's a lot to consider here but we would need to invent quite a lot of things along the way. Which, is very viable in the next few hundred years (which is how long we believe we can safely store fuel on site).
[0] https://www.britannica.com/science/nuclear-binding-energy
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).
Question 1: How many seconds until its below lethal levels.
Question 2: How many years will it take until the last atom is gone with a probability of 99%?
I think it's quite plausible that today's dry casks could last several centuries. So, we have a technology that will last as long as it could be intended to. Arguably it's better for our descendants to do this and let them deal with the waste, not needlessly do something much more expensive. Our descendants will not like that we squandered wealth and left them with larger debts or lower growth either. Always consider what else could be done with resources when you advocate their use.
However in some circumstances those types are actually safer to be around, since radiation that can't be stopped is also radiation that isn't interacting and dealing damage.
________________
This relates to the radioactive cookie puzzle, which has many variations, ex: "You have three cookies that emit alpha, beta, and gamma radiation respectively. Choose one cookie to eat, one to put in your pocket, and one to put in a thin lead box."
(Partial spoiler) Put the alpha-emitter in your pocket, since it'll be blocked by a layer of fabric and dead skin cells. (Your eyes remain vulnerable, though.) The lead-box would be overkill. Finally, even if it seems easy to manage, the alpha-radiation is not safe: Eating that cookie could kill you, since your important (living) inner cells would be damaged trapping its output.
Conversely, eating the gamma-ray emitter is sometimes the best call, because it's not going to be much worse than the other choices, and much of it will leave your body unimpeded.
The radioactivity of this isotope is so low that, as I understand it, one could replace every iodine atom in your body with this isotope and you'd still be okay. This would imply it's fine to dispose of this isotope by just dissolving it into the ocean. The ocean's total iodine is about 10^11 tons, so a disposal rate of ~10^4 tons/year would eventually (in ~a half life) make the ocean's iodine mostly I-129 (conservatively, assuming no exchange of iodine is occurring between the ocean and external reservoirs of the element.) This production rate is what would obtain in a totally nuclear powered world at today's primary energy consumption rate.
You're technically right.
With Uranium half-life of 4.5b years and current exposure of tens of thousands roentgens per hour, the roadmap to survivability extends well beyond the heat death of the universe, though.
https://en.wikipedia.org/wiki/Video_camera_tube
But yeah, still not great for making robots.
[1]: https://en.wikipedia.org/wiki/Nuvistor
[2]: https://archive.org/details/manualsbase-id-455546/page/4/mod...
> 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.
Energy does what energy does.
Essentially, they use optical fiber as radiation sensors on Fukushima. So, while the concern about cloudiness is valid, the reality is that at least some types of optical fibers work okay even there.
Still waiting on which one it'll be. Probably both to some extent.
But things are going to get weird and it's hard to predict the social consequences. Maybe robots get so cheap that there's no reason the have-nots don't have them, too (like today with smartphones and cars) and then there's no famine because food production is so easy with automation (???)
The madness will continue as long as he's in power.
That was a big problem with the Chernobyl reactor. The temporary sarcophagus was almost rubble, when they put up the big quonset hut.
https://en.wikipedia.org/wiki/Runaround_(story)
https://en.wikipedia.org/wiki/Runaround_(story)
Watch that account and see if it endorse | votes up a submission next week.
...
> About 880 tons of highly radioactive melted nuclear fuel remain inside the three damaged reactors
talk about starting small
I couldn't find fuel weight in a BWR-3, but a RBMK reactor (Chernobyl) contains between 150 and 200 tons of Uranium. Now, a RBMK runs natural uranium, so you're going to be using more fuel for the same power, but it suggests the number isn't totally whack.
I would not be surprised by it being a typo, but depending on what you include in "melted fuel" (fuel assembly, reactor parts, etc), 880 tons isn't outrageously high either.
> 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.
It isn’t the type of problem amenable to just bulldozing it into a hole, unless you’re Russian anyway.
It seems to me the fix would be to not have your backup generators below the water line.
Yes, I'm serious. TEPCO wanted to dump sea water into the reactors as a last resort so they wouldn't melt down, but the Japanese government at the time didn't allow it because the reactors would be rendered unusable.
Of course, the reactors melted down and became unusable anyway.
Fukushima #1 was a human failure and the only solution to that is a human solution. Any engineering solution will be foiled by a bigger human failure, as the saying goes.
We need to be fair here: Plans for potential flooding were made, the issue was nobody expected a tsunami that fucking tall and reasonably so.
Guidelines and such have been updated since so it (hopefully) won't happen again, but you can't fault engineers of the past for working with the data they had and coming to the conclusions they did.
that's less reasonable when you consider Japan's history with tsunami.
The events in 1933,1896, and 1993 produced tsunamis with larger wave heights than the Tohoku event.
https://www.tepco.co.jp/en/decommision/planaction/landwardwa....
Remove high level waste to a more stable environment is the first step in reducing those ongoing costs.
Wow. By the time they finish the cleanup, we could be running profitable fusion power plants, have humans living on mars, discovered new physics…
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.
However, it’s still tempting for me to respond to this fission-prevents-global-warming claim with my own appraisal. You’re right, it is certain that we’ll still be using fossil fuels. I’ve given up worrying about fossil fuels and global warming. It’s something I can’t do anything about, and I think it will be fine: the people who make the macro decisions decided decades ago that we didn't really need to / weren’t going to risk economic growth by suddenly reducing fossil fuel use as much as the scientists said would be needed. It was really a masterwork: the same political groups eager to go to war in the Middle East and hungry for tax breaks were kept more than eager to keep buying gas, effectively sending their money to the Middle East about once or more a week in many cases. There are some nuances that undermine the reasoning expressed in my last sentence, but I’m sure that those particular nuances weren’t the justification, as much of the public has indicated that they support bombing even Agrabah. [0]
Why didn’t we do enough? Well, lately it has turned out that geo-engineering was taboo only to indicate as an option, not to actually do when the time came. [1] It looks like the plan all along has been geo-engineering, while keeping the public on-edge about that to justify projects like fission plants. Fission research has long been an avenue to develop knowledge essential for nuclear weapons R&D. In the context of international relations and international nuclear treaties, the cover story of saving the planet makes even more sense as an essential. The Secretary of Energy was in Congress just the other day discussing compensation for victims of Manhattan Project radiation [2], a topic which has nothing to do with nuclear energy, unless nuclear energy is sometimes a codeword for nuclear weapons. Fission isn’t really important to stop global warming if we’re just going to implement geo-engineering.
[0] https://www.snopes.com/news/2015/12/18/agrabah-aladdin-repub...
[1] https://www.usatoday.com/story/news/weather/2024/05/24/can-g...
[2] https://m.youtube.com/live/Xwx5pLoDXIg?t=66m50s
Sweden did have a nuclear program but it was decommissioned in 1966. The program instead went exclusively into civilian energy production, with nuclear power plants being built from 1969 until 1980. The military did not show any interest since 1970, with nuclear weapons deemed way to expensive, ineffective, and the civilian research and military research diverging too much in order for continued cooperation.
Geo-engineering is interesting, but like nuclear weapons it is also a tool for mass destruction and warfare on a scale that even dwarf the largest nuclear weapons in existence. The R&D for geo-engineering in order to address global warming is indistinguishable from using it as a weapon. It order to make sure that geo-engineering does not cause mass destruction, it is essential to know what could trigger mass destruction.
- Humanity
https://scholarbank.nus.edu.sg/handle/10635/223658
The title suggests that the melted material will be removed soon but is not realistic. At this moment should say "will try to remove 3 grams from the >800 tons of melted fuel. At this pace, the place will be safe by natural means much before the robot will end the work.
Apart of this, I wonder... is this stuff still usable? There is something that could be done with this grams of melted dust that would worth the risk of spreading it around?
...
Second: why to design a robot for that, or move electronics close to this area so they can fry in seconds?.
The idea that must be some sort of robot (because some sort of idealized human rescuer figure is what the public expects) is not very smart. What they need is maybe (IMAO) a sort of "anteater-tongue machine" that just will try each crevice until finding the correct path. A sort of strictly mechanical machine moved from a safe distance with a real human brain taking the decisions much faster.
If you need to move a tube there are a lot of solid mechanical joints in the market tested since decades for every possible need. All needed is an axis able to rotate, a motor placed very far away, and a removable set of arms that would pick and vacuum the stuff and would double as "fuel rods" or something later when will be unavoidably contaminated. Just cut the tube in appropriate lengths and put the contaminated rod to sleep in the pool with the other stuff.
If electronics are an obstacle, just remove it entirely and use a stochastical movement instead a directed one.
Radioactive dust in the path could be grabbed with some type of greasy or sticky material before to be collected by a moving ring. No need to design a complicated claw here. There are several metallic types of grease available that could jail the dust and maybe even, dunno, provide benefits to block the dust radiation somehow into a matrix of metallic particles.
If you need to see the path, use echolocation or maybe run a camera forward for one second to retreat it fast to safety. The "tongue" could be used as a rail for the camera.
Alternatively, they could made the path safer first deploying a lead jacket made with tubes or plates where the robot can move. If the room is radioactive, line it in lead lames. That would also remove coins and crevices and would made the route much safer for people and machines and easier to navigate until the final part.
Even just planning to remove all of the melted fuel is a long way away.
I can't remember if they were talking about Unit 1 or Unit 2, but from what I understood is that due the collapsed rubble above/around the reactor, they only have a very narrow opening, which means they've struggled to use larger robots.
And I believe the robot operating centre is a bit of a distance away from the reactors too (probably so that the robot operators don't need to wear protective equipment).
> What they need is a sort of "anteater-tongue machine" that just will try each crevice until finding the correct path.
I think the problem is that once you get through all the debris, there's a big cavern. Hence why they're using some sort of crane robot on a rope (it reminds me a bit of a [claw machine game][1]).
[1]: https://en.wikipedia.org/wiki/Claw_machine
I see. Different situation then.