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Nuclear power plant fuel is mined from the ground. It has some measure of radioactivity, say X. It's then processed into fuel to be much more radioactive. The waste from the process is also more radioactive than when it was mined.
So the thought experiment / question would be "If we returned this
nuclear material to where we mined it with even less radioactivity per pound than how we found it, would that be acceptable?"
So you'd have a mine area with X amount of radioactivity, and after you mined all the Uranium, processed it, used it for power then blended the waste with the same inert material that surrounded it when it was dug up, the radioactivity in that area would be about 1/2 X.
Again, this would be silly but it would be a way to gauge what the mindset of the anti nuclear person was. If they're against reducing the radioactivity in nature that would be kind of hard to make another argument with and you could just move on.
Private companies going the nuclear route.
https://www.bbc.com...ticles/c748gn94k95o
[doctorremulac3, Jan 03 2025]
Wind Turbine Flex
https://www.youtube...watch?v=mL_MgUakQSc
[bs0u0155, Jan 06 2025]
[link]
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That's not how radioactivity works. It's not an "emissions per gram" thing across all types. The thing about radioactive materials is you can get more dangerous substances that emit less in total because they emit on a different wavelength. Also most radioactive waste is things like gloves, metal parts that were parts of a reactor, possibly contaminated floor sweepings, and so on. These things could mostly just be ground up with the rest, but they would act differently from the original material. My final point is that uranium in the ground is bound in a solid rock. The only way to put it back into solid rock is to melt rock together with the uranium, and that brings up enough problems to give the corpse of the Borg an erection. |
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So is there any way to return this material to the same or lesser state as far as danger of radiation exposure? For instance, if I take one gram of radioactive waste and mix it evenly with a ton of sand, it's safe no? There's no magic with any substance, they're all subject to laws of not even physics, but logic. |
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Let's look at poison as an analogy. If you take a gallon of cyanide and mix it with a gallon of CoolAid that's not good to drink. But mix it with 100,000 gallons it's probably fine no? Okay, one million gallons. Ten million? At some point it's safe. |
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My point is there IS a level of safety that can be reached through diluting a toxic substance, whatever it is. To say this can't be done gives an air of mysticism to these substances. There is a safe level of ANY toxic substance, including ground up radioactive boots, floor sweepings, gloves and face-masks. |
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As far as the solid rock thing, okay, put it in concrete. But again, it can be done theoretically, even if it's silly, which is clearly is. But that's why it's a thought experiment, not a proposal. |
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And there's a purpose for this. If they can agree that if there WERE a safe way to dispose of radioactive waste, then we're okay with nuclear power, then maybe we can be open to discussing more plausible ways of dealing with that waste. |
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So to be clear, this is a way to open dialog, not an actual proposal to deal with radioactive waste. |
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All I know is I'll be following the reopening of Three Mile Island with some interest as to how they modernize, if they do modernize. The control room from looks like exactly like the Simpsons intro. |
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Well I think the nukes are coming back, like it or not. I understand Google, Amazon, Microsoft and I think Oracle are just doing it on their own. (link) |
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I know with AI taking off we're gonna need a lot of juice to power that industry. |
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Explode it in a bomb, then it is diluted through the entire atmosphere |
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Chernobyl has shown that radioactivity has not kept life from thriving. |
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The waste heat is useful. |
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There are perks to be had from the waste. |
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We could probably use a bunch of it on the moon soon. |
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Let's suppose you have a uranium mine. You dig out many tonnes of uranium ore, that is, uraninite (UO2). |
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The most common isotopes in natural uranium are 238U (99.274%) and 235U (0.711%). We mainly want the 235U, so let's suppose we extract that, and put most of the 238U back. Isolating U235 is not actually straightforward, which is why nuclear bombs aren't commonplace, and also why that's not normally done - anything over 85% is "weapons grade" uranium; for energy generation the normal target is 3-5%. But let's suppose we reconstitute ore depleted of 235U. |
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Of course, there can be other radioactive elements in the mined material. A page I found online reports that the tailings (that is, rejected stuff from the mined material which isn't wanted) has about 75% of the initial radioactivity. |
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Okay, cool, so that's your mine basically refilled - the tailings are returned, and we took out less than a quarter of the actual ore. Actually, less than that if we're reprocessing nuclear waste - we already have a lot of 238U because only a small fraction gets used up, the rest can be carried forward. But now we want to actually use that lovely uranium235 goodness to make some electricity. |
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The isotope Uranium 235 has a half-life of 703,800,000 years, so *provided it's not crammed together in any significant density*, it's radioactive, sure, but not hideously so. That's why things like uranium glass were in widespread use for years without any obvious issues.
Obviously, we need the reaction to go faster than that. If you lump enough uranium together, you can get a chain reaction, and if you manage that carefully you can get energy out, while the uranium gets converted into a variety of decay products. It's actually not just one decay event per atom; the products are mostly themselves radioactive, often with shorter half-lives, and form a decay pathway. Real nuclear reactors also convert some of the U238 into plutonium, and that can be also be reacted to produce energy and more decay products. |
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Okay. So the decay products you get from a nuclear reactor have half-lives ranging from tiny fractions of a second (which happen inside the reactor, we basically don't need to worry about them in the waste, except as they are generated through ongoing decay further up the pathway), though days, weeks or months (relatively easy to get rid of... you just have to wait a bit), through years to tens of thousands of years. |
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I think it's clear that even thousands of years is much less than half a billion years, so nuclear waste can be much more radioactive - per unit time, in the short term - than the starting material. |
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Which is to say that you'd need more than the original mine's worth of tailings to 'dilute' the nuclear waste back to its original level of radioactivity. Furthermore, a number of the isotopes either directly in the decay pathway, or from transmutation of other nearby materials are bioaccumulated (iodine is the canonical example), or at risk of escape - through leaching by water, for example.
But the good news is that only about 3% of radioactive waste is long-term harmful (ie, radioactive for thousands of years). We might as well bite the bullet and just store that somewhere safely in concentrated form. |
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My bad, thought I clarified that. You aren't limited to the area it was mined or the original amount of surrounding material. |
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And again, just a thought experiment, you'd never actually do this because it's not a viable solution. Just a step towards getting control of any stigmas surrounding nuclear power. |
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And I'll be the first to repeat what's been pointed out. If our first exposure to gasoline was napalm with pictures of charred human remains, how excited would we be to pump natural gas into our houses and pump gasoline into our cars? Our first exposure to nuclear power was two cities vaporized in mushroom clouds. |
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Hey, I'd probably have some reservations about gasoline myself. Or at least some questions. I'd probably be reticent about bringing a can of this stuff to the woods and have my kids roast marshmallows on it. "Hey kids! Who wants napalm treats in an area where if we're not careful the stuff in this can we might destroy tens of thousands of acres of forest and kill every living thing it its path!" "Can we make smores?" "Sure! Just make sure not to kill thousands of animals and trees even people by being a little careless!" "YAY! SMORES!" |
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//You aren't limited to the area it was mined or the original amount of surrounding material.// |
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Well, sure, you can. But if it's not going back in situ, then you lose the only real benefit this has going for it - that you can say you've left the area in the same or better state than it started.
And, like, that couldn't even be true practically, but it would be some sort of justification which might mollify some people. |
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Really, one of the advantages nuclear power has is the smallness of the waste it produces. It might be dangerous, but it's tiny, and it should just be possible to store it away somewhere safe and practically forget about it.
In a world where people didn't crap their pants about some problems while ignoring much worse problems caused by the alternatives, it would be a reasonable solution. |
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Yes, but you're preaching to the choir. |
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Maybe adopting some of my gasoline rant as an extension of your, I'll call it, "Let's get some perspective on this." argument. |
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However we do this I think it's an important discussion to have. Whatever gets the dialog going works for me. |
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And hey, maybe I'm throwing rocks at specters, I haven't found a lot of people who are anti-nuke these days. I even heard that Greta Thunberg is pro nuke, and I think she might represent a pretty good portion of the youth and their views these days. |
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Actually, just occurred to me my gasoline faux-rant might backfire. Start a movement to eliminate natural gas heating homes. |
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I didn't realize the heating of natural gas was a problem. Or that homes are designed to accomplish that. Are they using heat pumps to dump heat from homes into natural gas storage tanks when higher pressure is needed? If so I don't see a problem with it. |
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Send the concentrated waste stuff into the sun and fuggedaboudit. Just make sure the rocket doesn't blow up on the pad... |
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No. The Moon needs it. What part of that is misunderstood? |
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We are going to need radioactive materials on the moon soon. |
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//It's not an "emissions per gram" thing// |
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It sort of is an "emissions per gram thing". There's a lot of radioactivity bound up in the world's granite, but that stops no-one from making kitchen counters out of it. Those two are sort of linked, because granite is a relatively low density emitter, most of the radioactivity is emitted INTO granite, which happens to be an excellent radiation shield. Very high density emitters are much more likely to emit into the environment than themselves. |
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//The thing about radioactive materials is you can get more dangerous substances that emit less in total because they emit on a different wavelength.// |
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Not just wavelength of X/gamma but also particle/wave with alpha/beta, but I get the point, you can generate concentrated and high energy waste from the nuclear industry. This tends to be short lived though. |
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//The only way to put it back into solid rock is to melt rock together with the uranium,// |
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Not usually uranium, that's a touch too valuable to waste, but exactly this. It's really easy to put stuff in rock, concrete is rock, chemically. Actually, we can do a lot better. Glass is very cheap and humans are very good at making it. Furthermore, it's impervious to water, it's beyond Earth's natural chemistry to degrade it, physically it's remarkable. |
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//Well I think the nukes are coming back, like it or not. I understand Google, Amazon, Microsoft and I think Oracle are just doing it on their own. (link)// |
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This is very informative, possibly on a number of levels. It implies that: |
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these corporations are big enough to take on nuclear power projects |
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they think the risk/benefit of nuclear power is a no-brainer |
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they do not trust the existing infrastructures to handle planned demand. |
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What happens if there is a nuclear incident? Do they still have the rights and responsibilities of people? Are Microsoft going to jail? Can they afford a clean up? Or is it the usual private gain/public risk? |
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//Just make sure the rocket doesn't blow up on the pad// |
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If you could just nail the "sure" part, and the energetics. |
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//we can be open to discussing more plausible ways of dealing with that waste.// |
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Offer to dispose of the spent wind turbine blades at the same time. |
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//Offer to dispose of the spent wind turbine blades at the same time.// |
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Nice!! Got a bit of an underlying zinger message as well no? |
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I'm struggling to understand why they're fiberglass. They're not a long way away from glider wings mounted to a hub, and I understand why glider wings are fiberglass, mass/weight is critical. For a wind turbine does weight matter? No, the whole blade array should be balanced. Mass matters, but only during spin up, and the generator can be de-loaded a little to help that, Shirley? I imagine it already is. |
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The profile of the blade is critical for efficiency, and molding fiberglass is an effective way of controlling that. Make the blades of aviation-wing grade aluminum and you can machine the profile carefully, but it's expensive at that scale and aluminum blades will always fatigue-fail. |
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Fiberglass is all well and good until the glass fibers start to work loose from the epoxy, like flexing a starched shirt collar, this is why they're thrown away. Steel or titanium are the ideal materials, I imagine they just can't be bothered putting they're big boy pants on to work out how to control the blade profile at that scale, I'd recommend a similar mold and go with hydroforming. |
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<wind turbines>
//I'm struggling to understand why they're fiberglass. They're not a long way away from glider wings mounted to a hub, and I understand why glider wings are fiberglass, mass/weight is critical. For a wind turbine does weight matter? No, the whole blade array should be balanced. Mass matters, but only during spin up,// |
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Have you considered what happens when a component fails? Even the 'lightweight' fiberglass/metal frame sails are pretty heavy overall and can disassemble spectacularly.
I imagine that they're built to be light so they can be as large as possible - for windmills, larger is massively better from an energy standpoint, so you want them to be as big as you can possibly get. If you make them heavier per unit volume of sail, you have higher tension loads along the sail axis, and higher compression load in the support column, which probably means they're harder to scale up. |
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These could be made with recycleable and repairable aluminum no? |
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Maybe the reason for fiberglass is financial, not structural. Costs a lot of money to replace those things. |
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Okay, here's a tinfoil hatter: the oil companies get to wet their beak. The fiberglass in fiberglass is held together with products made of petroleum I think. Plus it's not recyclable so the oil companies get their taste. |
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Hey, a conspiracy theory just has to be kind of interesting and plausible to be good. That one's not horrible. 2 out of 5 stars. |
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//These could be made with recycleable and repairable aluminum no?// |
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Tensile strength fiberglass: 3,400 MPa
Tensile strength of aluminium 'heat-treatable alloys': over 690 MPa |
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The unit there is megapascals, which is effectively force per unit area; bigger numbers are better.
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The value for aluminium there is the best number I found, while that for fiberglass is not; high-performance fiberglass has even higher values. Fiberglass apparently has a tensile strength up to 4 times that of steel! |
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So no, replacing fiberglass with aluminium would not be a great drop-in solution. |
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//If you make them heavier per unit volume of sail, you have higher tension loads along the sail axis, and higher compression load in the support column, which probably means they're harder to scale up.// |
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High winds are the overwhelming driver of the necessary strength. Blade weight increasing the compression on the support i think is also negligible compared to wind loading (the bend significantly, <link>). Steel also scales marvelously, see: bridges/ships etc. I wonder if flexibility is a driver? Dealing with unusually high wind loading is tricky, with fiberglass the blades could be made to flex significantly reducing apparent frontal area, also, by controlling the weave direction, you can control how they flex, so the blades could twist to make a more resilient angle of attack. |
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//Okay, here's a tinfoil hatter: the oil companies get to wet their beak.// |
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They do OK out of the energy required to make the concrete bases. Steel isn't exactly carbon neutral either. |
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True, technically nuclear isn’t either until we get electric powered mining equipment, oar trucks etc. |
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Still seems like replacing fiberglass with something recyclable would be a good thing. I’ve seen those windmill blade graveyards, friggin’ massive. |
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//High winds are the overwhelming driver of the necessary strength. Blade weight increasing the compression on the support i think is also negligible compared to wind loading (the bend significantly,// |
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I don't think the tower strength is an issue. The tower is also generally not made of fiberglass - it's typically mostly steel. I don't see why you'd bring this distraction up, to be honest.
We were talking about why the blades are made of fiberglass - you said they didn't have to be light, I pointed out they /did/ have to be light so they could be as big as possible - for efficiency reasons. |
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:: The equation for centripetal force is Fc=mv^2/r. where m= mass kg, v= velocity in radians, r= radius in metres ::
(Note that the mass is distributed along the blade in our case, so you can't simply drop total values in, you'd need to integrate, but the point stands.) |
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Obviously, if you use a heavier design for a turbine blade, the rotating mass will be higher. The blades have to carry this force, or they fail and are thrown away from the tower. Not ideal.
Therefore, at any particular margin of safety, and with some particular sail design, the compositionally lighter blade can be larger.
The power a wind turbine can generate is dependent on the square of the radius, so bigger is distinctly better. |
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The problem with wind as a power source is it's rather diffuse - that is, unconcentrated and the wins are borderline marginal - if you fuck around making things inefficient, you basically might as well not bother, you're using more energy than you're generating.
They're using fiberglass because they've investigated and decided it's the best thing to use, not because of big epoxy, or holding shares in land-fill or whatever. |
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//you said they didn't have to be light, I pointed out they /did/ have to be light so they could be as big as possible - for efficiency reasons// |
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I don't think weight is a massive driver here, certainly not the weight/mass difference between a high grade steel and fiberglass. We can use aircraft propellers as a guide here, if Fc=mv2/r, then an aircraft prop is approx. 500x v and 100x shorter, so 50,000 less Centripetal force? and they're still overwhelmingly aluminum/steel/wood. |
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These blades I think, are about the largest fiberglass objects I can think of, with the exception of maybe boats. As boats scale up, the material of choice again becomes steel. I'm starting to think that corrosion resistance might be the biggest driver. |
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