What-If 0029: "Spent Fuel Pool"

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Fire Brns
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Re: What-If 0029: Spent Fuel Pool

Postby Fire Brns » Wed Jan 23, 2013 8:10 pm UTC

ImagingGeek wrote:
Fire Brns wrote:
ImagingGeek wrote:
armandoalvarez wrote:Does this water being a such a good absorber of radiation thing mean that inhabitants of underwater bubble cities, even ones in shallow water, would have lower cancer rates than those of us living on dry land?

Not really. Much of the radiation that we encounter that causes cancer is in the materials we build with (a lot of bricks are made of uranium-containing clays, for example). Medicals sources, etc, also account for a lot. Radon is a major source; depending on your building materials and air-handeling technology you *might* get away from it underwater.

Globally, about 10% of cancers are though to involve exposure to radiation, about 1/3rd of that medical, so at-best you'll reduce your cancer burden by 6 or so percent. And that's assuming you don't introduce new (or higher-dose) non-radiative carcinogens in your colony.

Bryan

Smoke detectors give off a lot of radon which if left unventilated is perfect for causing lung cancer. Underwater bubble colonies would need excellent fire detection systems.

This is incorrect. Americium-based smoke detectors do not release volatile fission products. Americium breaks down into an isotope of neptunium which is solid & has a multi-million year half-life.

Bryan
That's assuming Americium based detectors are used. I'll have to look into getting those now. As it is there is a greater chance for such place to concentrate radioactives and carcinogens.
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Re: What-If 0029: Spent Fuel Pool

Postby MarkSmash » Wed Jan 23, 2013 8:10 pm UTC

ijuin wrote:
craigmpeters wrote:I saw a great article about storing radiation so that we can tell people thousands of years in the future that it is unsafe about how they would convey by architecture and symbols "do not dig this up you idiot, man did some stupid stuff here and do not disturb it"

I cannot find it unfortunately.


The most worrisome problem is that even if we were able to communicate our intentions to these future people, who might have long-since forgotten any of the languages that we currently use, the mere fact that we are telling them to keep away will make it a "forbidden fruit" issue, sort of like with warnings placed on tombs. The mere fact that we don't want them digging it up might lead some of them to think that it is a buried treasure rather than poison. This goes doubly if they happen to be a non-industrial society and have no concept of radiation poisoning, and therefore wouldn't believe that the nuclear waste would kill you just by being near it without touching it.


There's a story in the book 'Cradle to Cradle' by William McDonough about a Navajo Elder attending a big conference to determine how best to label nuclear waste materials so that visiting aliens would know it was dangerous. After listening for a while, he started laughing. When he was asked why he was laughing, he said, "You don't need to put up a sign to warn visiting aliens. WE will tell them."

I suppose we tend to forget that we are a part of this world.

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Re: What-If 0029: Spent Fuel Pool

Postby Sizik » Wed Jan 23, 2013 9:12 pm UTC

I think the assumption is that we will all be dead/gone, and as such are unable to directly tell them.
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Re: What-If 0029: Spent Fuel Pool

Postby firechicago » Wed Jan 23, 2013 9:45 pm UTC

tibfulv wrote:"Though I'd make time for a brew first. Want one?"

Only if it comes pre-nuked.

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Re: What-If 0029: Spent Fuel Pool

Postby MarkSmash » Wed Jan 23, 2013 9:54 pm UTC

Sizik wrote:I think the assumption is that we will all be dead/gone, and as such are unable to directly tell them.


I suppose the point is, that a 'Western' point of view sees humans as separate from nature and also easily removable. The aboriginal world view is that we are inseparable from nature; you can no easier remove humans as you could trees or insects or clouds.

Maybe the fact that modern thinking has envisioned global anhiliation and our science has made this outcome plausible, distinguishing us from previous generations. However, one can see that we also tend to see ourselves as strangers to our own planet.

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Re: What-If 0029: Spent Fuel Pool

Postby Fire Brns » Wed Jan 23, 2013 10:19 pm UTC

MarkSmash wrote:
Sizik wrote:I think the assumption is that we will all be dead/gone, and as such are unable to directly tell them.


I suppose the point is, that a 'Western' point of view sees humans as separate from nature and also easily removable. The aboriginal world view is that we are inseparable from nature; you can no easier remove humans as you could trees or insects or clouds.

Maybe the fact that modern thinking has envisioned global anhiliation and our science has made this outcome plausible, distinguishing us from previous generations. However, one can see that we also tend to see ourselves as strangers to our own planet.

All trees or all insects but any one species can easily be wiped out; there are tree species with less than 1000 documented specimens alive and a renewal rate lower than the death rate. Humans would be the most difficult mammal to remove as we have the greatest population but that does not make our own destruction -at least in the cultural sense- impossible.

Political restructuring is the most dangerous threat to accurately protecting nuclear disposal sites. We do not have very accurate records from the Roman Empire but they did their fair share of documentation. Any number of factors could make knowledge of such sites disappear from the books. Especially as we rely more and more on digital rather than hard copy documentation.
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Re: What-If 0029: Spent Fuel Pool

Postby ShuRugal » Thu Jan 24, 2013 12:54 am UTC

J Thomas wrote:I'll tell you a much safer way. We can take our radioactive waste and dump it in the sun. The sun is so huge that a few tons of heavy metals cannot possibly have any effect on it. They will disappear without a trace. If they have some sort of influence on one little sunspot or flare or something, it won't matter.



you cant be serious. You know how much energy it takes to get something into the sun? The earth has an average orbital speed of almost 30 km/s, most of which would need to be shed in order to make a collision course with the sun (a close enough pass for burnup would not be sufficient, we don't want a cloud of vapourized radioactive waste intersecting out orbital path, do we?). that's -after- escaping earth orbit.

using this chart we see that from earth surface to lunar orbit requires a delta-v of approximately 4 km/s.

Now, assume we do some fancy lunar slingshot with our garbage rocket and we can manage a retro-orbit breakawy from earth orbit to sol orbit with a total (from launch to breakaway) of 5 km/s delta v needing to be made from by rocket thrust. Now we are just behind the earth on a solar orbit going about the same speed. great, there's the easy part done.

Now our waste rocket is orbiting the sun at slightly less than earth orbital speed, but still damn close to 30 km/s. Let's assume that we only need to make a delta-V of 20 km/s to narrow out our orbit enough to hit the sun (the sun is a pretty wide damn target after all, and we are not particular about exactly where we hit it, or the impact angle, just getting into the corona will be enough, drag can do the rest from there)

So, to get our nuclear waste into the sun, we only need a total delta-v of roughly 25 km/s, or five times the total delta-v budget of an apollo mission (not including the landing phase).

now, the real fun part, how much fuel do we need? Apollo used 2.5 million kilograms of fuel (again discounting landing phase) to achieve that 5 km/s delta-v. We need five times the delta-v to hit the sun. If your remember from the model rocket 'what if' when the math went from a 2 km/s delta-v to a 10 km/s delta-v, the mass of the rocket went from a tow truck (about 5 tons) to the great pyramid of giza (6 million tons). Now, model rocket engines have absolute shit efficiency (specific impulse), a tenth or less what a real rocket has. So lets assume that instead of needing a factor of 1 million, we need only 100,000 times as much fuel.

Now we have a rocket with 250 billion kilograms of fuel, to move a few tons of nuclear waste into the sun. Granted, this number is the product of some serious rough guessing, but even if i've overcalculated by a factor of 100 (btw, if someone who knows the data to do this accurately wants to correct me, please do) we still are using 2.5 billion kilos of fuel to get rid of a few tons of nuclear waste.

the atmospheric pollution just from launching enough rockets to get rid of the hundreds (thousands?) of tons of the crap already laying around would be nightmarish, not to mention continuing to do this a few times a year as nuclear production picks up. Also, the environmental damage from manufacturing all that fuel, not to mention the inevitable spills and explosions, and rocket fuel is some of the nastiest shit humanity has ever produced as far as environmental damage goes. We'd be better off disposing of spent fuel by converting it to warheads and blowing it up.

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Re: What-If 0029: Spent Fuel Pool

Postby Pfhorrest » Thu Jan 24, 2013 1:14 am UTC

I may be wrong, but I think JT was sarcastically suggesting we dump heavy nuclear materials into the sun on the same "what could go wrong" flippancy as the suggestion to dump them in the ocean. I'm not an expert on stellar fusion but IIRC aren't there some mechanisms by which heavy elements can disrupt the stellar life cycle?

EDIT: I know the difference between fission and fusion.
Last edited by Pfhorrest on Thu Jan 24, 2013 5:16 am UTC, edited 1 time in total.
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Re: What-If 0029: Spent Fuel Pool

Postby drummerpatch » Thu Jan 24, 2013 3:36 am UTC

Pfhorrest wrote:I may be wrong, but I think JT was sarcastically suggesting we dump heavy nuclear materials into the sun on the same "what could go wrong" flippancy as the suggestion to dump them in the ocean. I'm not an expert on stellar fission but IIRC aren't there some mechanisms by which heavy elements can disrupt the stellar life cycle?


I don't actually know the answer. What I do know is that it would be stellar fusion. Fission is the breakdown of large elements (usually heavy metals, although really it's possible in anything larger than iron -- any smaller, and energy input is greater than energy output) into smaller ones by way of neutron bombardment (releasing free neutrons -- creating a chain reaction -- and free protons, which are gamma rays). Fusion is the joining of two smaller atoms (generally something smaller than iron, because above that energy input is higher than energy output) into larger ones by way of extreme heat and pressure (essentially forcing rapid high-energy collisions between atoms), releasing excess energy (thereby creating a chain reaction) and free protons and neutrons, with are gamma and beta rays respectively.

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Re: What-If 0029: Spent Fuel Pool

Postby Max™ » Thu Jan 24, 2013 4:19 am UTC

Have Tartakovsky design it with the help of 8 year olds.

Image

As for the sun, perhaps if you dropped planetary masses of iron or heavier elements into a star it would be noticeable pretty quickly, but for the most part no, stars getting various materials dumped into them from neighbors isn't uncommon.

I wouldn't start doing this to a high mass neutron star though, not unless I didn't like whoever lived within a certain number of light years from it.


For the record, these: http://en.wikipedia.org/wiki/Titan_IIIE were enough to launch these: http://en.wikipedia.org/wiki/Helios_probes into orbits which passed just inside the orbit of mercury, which also set a speed record for fastest manmade space vehicle as I recall, hitting 40 mi/s (70 km/s), which is pretty damn fast.
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Re: What-If 0029: Spent Fuel Pool

Postby Pfhorrest » Thu Jan 24, 2013 5:27 am UTC

drummerpatch wrote:What I do know is that it would be stellar fusion. Fission is the breakdown of large elements...

Yes, I know this. Brain fart. Sorry.

However:

...into smaller ones by way of neutron bombardment (releasing free neutrons -- creating a chain reaction -- and free protons, which are gamma rays).

I am pretty sure that you are confusing protons and photons here. Gamma rays are electromagnetic radiation and thus made of photons, not protons.

Likewise:

...free protons and neutrons, with are gamma and beta rays respectively.

Gamma rays are made of photons again, and beta rays are high-energy electrons and positrons. The only radiation made of either protons or neutrons is alpha radiation, which is made up of helium nuclei, two protons and two neutrons each.

Also, I'm pretty sure that beta decay doesn't happen in fusion, only in fission, and likewise alpha decay (well, I suppose hydrogen fusion does end up with a lot of high-energy helium nuclei floating around, but I don't think that counts).
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Re: What-If 0029: Spent Fuel Pool

Postby ijuin » Thu Jan 24, 2013 7:27 am UTC

Pfhorrest wrote:Also, I'm pretty sure that beta decay doesn't happen in fusion, only in fission, and likewise alpha decay (well, I suppose hydrogen fusion does end up with a lot of high-energy helium nuclei floating around, but I don't think that counts).

If two protons collide and fuse, the diproton created is unstable and one proton will decay into a neutron via inverse beta decay, releasing a positron and a neutrino. Within a star, the positron thus created will encounter an electron long before it has a chance to escape from the star. The solar wind, however, is made of ions that have been blasted out of the sun's corona, and is mostly hydrogen and helium nuclei with some electrons.

Anyway, in regards to the "dump waste into the sun" concept, the sun is frakking huge--it's literally one million times bigger than the Earth (1/3 of a million times more massive, but 1 million times more volume). You could drop an entire Earth-sized planet into the sun and it would only cause moderate flares--enough to knock out our satellites and some ground electronics, but hardly enough to disrupt meteorological cycles.

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Re: What-If 0029: Spent Fuel Pool

Postby Mikeski » Thu Jan 24, 2013 7:45 am UTC

Pfhorrest wrote:I'm not an expert on stellar fusion but IIRC aren't there some mechanisms by which heavy elements can disrupt the stellar life cycle?

Probably. Can we find enough of the stuff to make it happen?

Consider our moon. Even looking at with the naked eye, it's a cratered mess, due to all the stuff that's randomly slammed into it over a few billion years. The sun is a vastly larger and more-gravitational target. How much non-H/He mass do you think has slammed into it over time? I don't think we can compete.

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Re: What-If 0029: Spent Fuel Pool

Postby Klear » Thu Jan 24, 2013 9:17 am UTC

Just imagine: suppose we WANTED to shut down the sun by any means we can think of. Do you think we could pull it off? I doubt it. With the difficulty of destroying just Earth, destroying sun has to be much more impossible.

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Re: What-If 0029: Spent Fuel Pool

Postby stianhat » Thu Jan 24, 2013 9:45 am UTC

J Thomas wrote:Are you serious?

Wouldn't you want to completely understand the oceans first? What if plankton concentrated the radioactivity enough to mostly kill themselves, what then?

What if fish eat the radioactive plankton and we have to give up seafood? Well that isn't so bad, I never liked seafood that much anyway. What if seabirds eat the fish and then come poop on you? How do you know what to expect?

I'll tell you a much safer way. We can take our radioactive waste and dump it in the sun. The sun is so huge that a few tons of heavy metals cannot possibly have any effect on it. They will disappear without a trace. If they have some sort of influence on one little sunspot or flare or something, it won't matter.

We don't have to know all about how the sun works to be completely sure that nothing we do can affect it in the slightest. There are people who say that if we don't completely understand how the sun works that we might possibly cause it to become more variable, or maybe go out or something. They're stupid. They don't realize how *big* and *massive* the sun is. It's sheer common sense that our wastes can't do anything at all to it.


If radioactive materials somehow concentrate in plankton, we would not have existed. The largest source of uranium is and has always been the sea. Just not very economical to refine it from there. Anyway, the volume of the sea is so large that the dilution of added radioactive material would be homeopathical at worst. As far as dumping radioactive waste into the sun, sounds smart, but how are you gonna get it there? What if your rocket explodes somewhere in the stratosphere? Hello nuclear holocaust?

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Re: What-If 0029: Spent Fuel Pool

Postby J Thomas » Thu Jan 24, 2013 11:32 am UTC

ShuRugal wrote:
J Thomas wrote:I'll tell you a much safer way. We can take our radioactive waste and dump it in the sun. The sun is so huge that a few tons of heavy metals cannot possibly have any effect on it. They will disappear without a trace. If they have some sort of influence on one little sunspot or flare or something, it won't matter.


you cant be serious.


No, I wasn't serious at all.

You know how much energy it takes to get something into the sun? The earth has an average orbital speed of almost 30 km/s, most of which would need to be shed in order to make a collision course with the sun (a close enough pass for burnup would not be sufficient, we don't want a cloud of vapourized radioactive waste intersecting out orbital path, do we?). that's -after- escaping earth orbit.


Well, but nuclear power plants are kind of dangerous. Wouldn't it make sense to put our nuclear power plants in orbit and then just beam down the energy? That way if anything goes wrong it will be harmlessly out in space where it doesn't matter, and not down here with us.

.... Now we have a rocket with 250 billion kilograms of fuel, to move a few tons of nuclear waste into the sun. Granted, this number is the product of some serious rough guessing, but even if i've overcalculated by a factor of 100 (btw, if someone who knows the data to do this accurately wants to correct me, please do) we still are using 2.5 billion kilos of fuel to get rid of a few tons of nuclear waste.


Obviously, you don't do it that way. We would use nuclear energy to push our rockets. How else are we going to move all those nuclear power plants into space? And then we have plenty of energy available to dump the waste into the sun where it can never do any harm to anybody.

I actually heard this seriously proposed. I'm pretty sure the place I saw it was the science fact section of Analog magazine, in the late 1970's or early 1980's. I believe it was Jerry Pournelle but maybe not. It makes a kind of sense. To put enough stuff into space to get a space society, we will need nuclear rockets. With nuclear rockets we can put thousands or millions of nuclear power plants into space where they will be completely safe. We will have plenty of power to lift everything else we need to lift, and plenty of power to dump radioactive wastes into the sun. With one proposal it solves the problems of unsafe nuclear power plants, unsafe nuclear waste, chemical rockets, and getting off the planet while the getting's good.

At about the same time Pournelle argued that nuclear fusion power plants will be a good thing because they create lots of neutrons, so any terrorists who try to steal nuclear material from them will quickly fry themselves.
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Re: What-If 0029: Spent Fuel Pool

Postby J Thomas » Thu Jan 24, 2013 11:59 am UTC

Klear wrote:Just imagine: suppose we WANTED to shut down the sun by any means we can think of. Do you think we could pull it off? I doubt it.


Perhaps we just don't know how yet.

If you take a thousand gallons of sterile wort and you add 1000 yeast cells, you can get beer.

If you take a functioning brain and you add a few thousand prion molecules you can get scrapie etc.

Is there some way that our sun is tenuously balanced, so that some small event could disrupt that balance? I dunno. Mikeski and Max point out that lots of stuff falls into suns and yet novas are rare. I expect that most of what falls into suns in binary systems etc has long half lives, and it's rare for things like our nuclear waste to do that. Would that make any difference? I dunno.

I think it's reasonable to imagine that nothing we do could affect the sun, given what we know now. So, how sure are you about that? Would you bet our sun on it?
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Re: What-If 0029: Spent Fuel Pool

Postby PolakoVoador » Thu Jan 24, 2013 12:00 pm UTC

You could send Jupiter right into Sun's face and it would merely sneer at your feeble attempt to hurt him.

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Re: What-If 0029: Spent Fuel Pool

Postby Klear » Thu Jan 24, 2013 12:23 pm UTC

I'm absolutely sure that if an attempt to snuff out the sun involves tossing Jupiter into it, it would be much much easier to destroy Earth, which is by no means a small feat.

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Re: What-If 0029: Spent Fuel Pool

Postby ImagingGeek » Thu Jan 24, 2013 2:17 pm UTC

Fire Brns wrote:That's assuming Americium based detectors are used. I'll have to look into getting those now. As it is there is a greater chance for such place to concentrate radioactives and carcinogens.

All non-americium detectors rely on non-radioactive detection technologies such as light scattering.

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Re: What-If 0029: Spent Fuel Pool

Postby J Thomas » Thu Jan 24, 2013 2:46 pm UTC

PolakoVoador wrote:You could send Jupiter right into Sun's face and it would merely sneer at your feeble attempt to hurt him.


I expect so. Still, a mosquito which can viciously bite you in the face without you even noticing, can give you yellow fever and kill you.
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Re: What-If 0029: Spent Fuel Pool

Postby Fire Brns » Thu Jan 24, 2013 3:39 pm UTC

ImagingGeek wrote:
Fire Brns wrote:That's assuming Americium based detectors are used. I'll have to look into getting those now. As it is there is a greater chance for such place to concentrate radioactives and carcinogens.

All non-americium detectors rely on non-radioactive detection technologies such as light scattering.

Bryan

Interesting, I remember encountering something about radon being released into the home around the same time I was researching smoke detectors. Must be memory substitution, I must do more research.
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Re: What-If 0029: Spent Fuel Pool

Postby Pfhorrest » Thu Jan 24, 2013 10:41 pm UTC

IIRC radon occurs naturally in the atmosphere but being a heavier part of it will tend to accumulate to sometimes-dangerous concentrations in low-lying enclosed areas like basements.
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Re: What-If 0029: Spent Fuel Pool

Postby Fire Brns » Thu Jan 24, 2013 11:43 pm UTC

Ok, that makes sense. I was researching ventilation at the same time.

To the nuclear wast disposal suggestion. We don't need to drop it into the sun, just in a random direction in space.
As for getting it into space, a sabot shell to contain the radioactives launched from a mass driver would be sufficient to get it out of the atmosphere at escape velocity. Sabot isn't the best term but I'll use it here. All without the risk of exploding like a conventional rocket or producing pollution to make said rockets. We would need to be willing to part with a lot of radiation absorbing and magnetic metals to build the sabots.
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Re: What-If 0029: Spent Fuel Pool

Postby dreadengineer » Thu Jan 24, 2013 11:51 pm UTC

ImagingGeek wrote:
armandoalvarez wrote:Does this water being a such a good absorber of radiation thing mean that inhabitants of underwater bubble cities, even ones in shallow water, would have lower cancer rates than those of us living on dry land?

Not really. Much of the radiation that we encounter that causes cancer is in the materials we build with (a lot of bricks are made of uranium-containing clays, for example). Medicals sources, etc, also account for a lot. Radon is a major source; depending on your building materials and air-handeling technology you *might* get away from it underwater.

Globally, about 10% of cancers are though to involve exposure to radiation, about 1/3rd of that medical, so at-best you'll reduce your cancer burden by 6 or so percent. And that's assuming you don't introduce new (or higher-dose) non-radiative carcinogens in your colony.

Bryan


Also, background radiation already varies widely by geographic location, but there's actually been no observed correlation between it and cancer rates. For example, there are cities in Iran where the background radiation from local minerals yields roughly the U.S. federal occupational limit of 5 Rem/yr, and residents don't have higher cancer rates than places where it's a more typical 300 mRem/year.

So the data kind of points to the conclusion that there's a radiation threshold below which it doesn't matter. (For conservatism, regulations still assume that there's additional risk even at low levels, but this is purely theoretical. It's calculated by just taking a linear proportion of the observed risk at high levels.)

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Re: What-If 0029: Spent Fuel Pool

Postby dreadengineer » Fri Jan 25, 2013 12:00 am UTC

tibfulv wrote:Had a thought. How about storing the materials under the sea floor near a subduction zone? We could let the mantle take care of the problem. Of course we could then never use it again, and we would have to store it away from volcanoes.


This has been proposed and would work perfectly well. A big reason we don't do it is that you'd need international approval, so a bunch of backward or irrationally anti-nuclear countries in the U.N. could block it. Also, within around 200 years, the near-surface deposits of uranium will be exhausted, so we'll likely want to reprocess the spent fuel eventually. Yucca Mountain is designed with this in mind; the dry-storage casks are basically on railcars so they can easily be pulled out again when we decide to reprocess.

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Re: What-If 0029: Spent Fuel Pool

Postby KrytenKoro » Fri Jan 25, 2013 1:52 am UTC

J Thomas wrote:
PolakoVoador wrote:You could send Jupiter right into Sun's face and it would merely sneer at your feeble attempt to hurt him.


I expect so. Still, a mosquito which can viciously bite you in the face without you even noticing, can give you yellow fever and kill you.


I'm breaking a retirement to post this, but it needs to be said:

Stars aren't some delicately balanced thing. They're the very definition of "make it bigger until it works". You can't kill a star until it's core is literally choked with heavy elements, and even that is going to require more heavy elements than there are on Earth.

Stars expire from running out of fuel (in the core). They don't get "poisoned".
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Re: What-If 0029: Spent Fuel Pool

Postby mattdeclaire » Fri Jan 25, 2013 2:08 am UTC

I've got two friends that have personally worked at nuclear power plants. Here is what they had to say after reading the comic.

Friend 1

Ha! I like the write up! The stick figures make it. I distinctly remember a conversation between Friend 2 and I about just this years ago. But I have a couple of unanswered questions from this overly simplistic article however:

1) what about the contamination (small invisible radioactive particles) that would be left on your skin and in your hair after you leave the pool? They filter/scrub the water pretty well, but there's still some bad stuff in there. Just ask Friend 2 how hard it is to remove things from the spent fuel pool. He has done it many, many times. Needless to say, you cant just put on your flip flops and towel dry.

2) what about the pool water that you would end up swallowing? Try swimming without opening your mouth. Its practically impossible. Any swallowed contamination would coat your stomach and you wouldnt be able to remove it, further increasing your total body dose as it slowly decays inside you. How about water in your eyes or ears? Or your bum, or worse yet your pee hole.

3) while the average temperature of the pool is as stated, for the first couple days after they empty the reactor to refuel there are some pretty significant thermals or "boils" happening in the pool. Its not actually boiling, but it appears that way (I've seen it, and it almost looks like its steaming). That water is significantly hotter than the average pool temp. Water at 50C (122F) in one of those thermals wouldnt feel so great. It wouldnt take too long to boil your potatoes if you swam right after the start of a refuel outage.

Friend 2

Good article and fairly accurate.

We have one of the cleanest pools in the industry but you still would not catch me swimming in it. You never know when you might encounter a hot particle, and I can think of several areas that I do not want a hot particle to come in contact with. We keep our pools around 75 F just for reference. I would argue that there might be more dose then the article states at the deeper depths. At the surface of the pool we get about .0001 Rem/hr. Years ago a rad protection tech just for fun took a radiation monitor and stuck it down into the pool (he made sure to water proof it). From about 1 foot away the monitor read 12000 Rem/hr. So yes, water does a good job at shielding, we keep about 30ft of water above the top of the fuel assemblies.

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Re: What-If 0029: Spent Fuel Pool

Postby ijuin » Fri Jan 25, 2013 8:05 am UTC

J Thomas wrote:Well, but nuclear power plants are kind of dangerous. Wouldn't it make sense to put our nuclear power plants in orbit and then just beam down the energy? That way if anything goes wrong it will be harmlessly out in space where it doesn't matter, and not down here with us.

Beaming power down from space gives you one of two problems: either your beam is concentrated enough that somebody malicious who takes control of it can redirect it to fry areas of a city, or else the beam is spread out enough that you need a kilometers-wide receiving area for it on Earth (i.e. much like a solar energy farm, though the beamed power would let it keep running at night).

Pfhorrest wrote:IIRC radon occurs naturally in the atmosphere but being a heavier part of it will tend to accumulate to sometimes-dangerous concentrations in low-lying enclosed areas like basements.

Well, Radon is the heaviest element that is gaseous at human temperatures, and only a few compounds that are gaseous at such temperatures are denser (e.g. sulfur hexaflouide). That would definitely make it tend to concentrate in poorly-ventilated low-lying spots.

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Re: What-If 0029: Spent Fuel Pool

Postby lux44 » Fri Jan 25, 2013 9:47 am UTC

We know spent fuel pools can be safe to swim in because they’re routinely serviced by human divers.

Except when the pools are not serviced by human divers, like in Fukushima, where there was so little water (so many rods) that the water boiled off when the circulation pumps broke down.

Fantastic project, the what-if, many-many thanks for doing it!

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Re: What-If 0029: Spent Fuel Pool

Postby mfb » Fri Jan 25, 2013 2:29 pm UTC

J Thomas wrote:Well, but nuclear power plants are kind of dangerous. Wouldn't it make sense to put our nuclear power plants in orbit and then just beam down the energy? That way if anything goes wrong it will be harmlessly out in space where it doesn't matter, and not down here with us.

You do not have access to cooling water, and blackbody radiation would require really huge radiators. Not to mention the mass of the reactor itself. You would increase building costs per reactor from some billions to some trillions.


It is not necessary to hit the sun - a high earth orbit would be sufficient. Or, if you like, add an ion engine or a solar sail to eventually leave earth. The solar system is so huge, you won't hit anything within hundreds of millions of years unless you carefully plan the course to do so.

stianhat wrote:What if your rocket explodes somewhere in the stratosphere? Hello nuclear holocaust?
Protect the payload. A castor container can survive an exploding rocket.

J Thomas wrote:Is there some way that our sun is tenuously balanced, so that some small event could disrupt that balance? I dunno.

The sun does not have life. In addition, your examples are not appropriate: You have to ask "what happens if I add another yeast cell to the existing 1 trillion?". The sun already has all elements, we would just increase the fraction of some of them by a tiny amount.

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Re: What-If 0029: Spent Fuel Pool

Postby eran_rathan » Fri Jan 25, 2013 2:37 pm UTC

Pfhorrest wrote:IIRC radon occurs naturally in the atmosphere but being a heavier part of it will tend to accumulate to sometimes-dangerous concentrations in low-lying enclosed areas like basements.

It also occurs from natural radioactive decay of uranium in some types of granite (New England is rather prone to this).
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Re: What-If 0029: Spent Fuel Pool

Postby J Thomas » Fri Jan 25, 2013 3:51 pm UTC

KrytenKoro wrote:
J Thomas wrote:
PolakoVoador wrote:You could send Jupiter right into Sun's face and it would merely sneer at your feeble attempt to hurt him.


I expect so. Still, a mosquito which can viciously bite you in the face without you even noticing, can give you yellow fever and kill you.


I'm breaking a retirement to post this, but it needs to be said:

Stars aren't some delicately balanced thing. They're the very definition of "make it bigger until it works". You can't kill a star until it's core is literally choked with heavy elements, and even that is going to require more heavy elements than there are on Earth.

Stars expire from running out of fuel (in the core). They don't get "poisoned".


As far as I know, you are right. There is not enough evidence yet to be at all confident that you are right that it always goes the way you think it does.

It wasn't all that long ago that scientists were sure that stones never fell from the sky. They attributed eyewitnesses who claimed to see stones fall from the sky as liars or victims of mass hallucination. Thomas Jefferson interviewed a collection of reputable people who claimed to see a meteor, and decided that maybe stones occasionally fall from the sky. But it was true that almost all of the stones that will ever fall from the sky have already fallen, and almost all of the stones that are still in the sky will stay there for a very long time.


mfb wrote:The sun already has all elements, we would just increase the fraction of some of them by a tiny amount.


Well, yes. But when you put it that way, the earth already has all elements and our nuclear waste won't increase the fraction at all. So we could just spread the waste around our cities and farmland with no harm.
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Re: What-If 0029: Spent Fuel Pool

Postby speising » Fri Jan 25, 2013 8:12 pm UTC

Well, yes. But when you put it that way, the earth already has all elements and our nuclear waste won't increase the fraction at all. So we could just spread the waste around our cities and farmland with no harm.


Actually, that doesn't sound unreasonable. The fuel was mined and refined in the first place. Why don't we just dilute it with the remains of the refinement and put it back in the old mine?

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Re: What-If 0029: Spent Fuel Pool

Postby Pfhorrest » Fri Jan 25, 2013 8:36 pm UTC

speising wrote:
Well, yes. But when you put it that way, the earth already has all elements and our nuclear waste won't increase the fraction at all. So we could just spread the waste around our cities and farmland with no harm.

Actually, that doesn't sound unreasonable. The fuel was mined and refined in the first place. Why don't we just dilute it with the remains of the refinement and put it back in the old mine?

I too would like to hear the answer to this question.
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Re: What-If 0029: Spent Fuel Pool

Postby Fire Brns » Fri Jan 25, 2013 9:03 pm UTC

Pfhorrest wrote:
speising wrote:
Well, yes. But when you put it that way, the earth already has all elements and our nuclear waste won't increase the fraction at all. So we could just spread the waste around our cities and farmland with no harm.

Actually, that doesn't sound unreasonable. The fuel was mined and refined in the first place. Why don't we just dilute it with the remains of the refinement and put it back in the old mine?

I too would like to hear the answer to this question.

It would likely need to be melted back down into a solid mass as it was found which risks the gaseous loss of radioactives or else risk being washed from the porous sandy ground or absorbed by plants.

Uranium tends to be strip mined as well, it's not as simple as sticking it in a cave tunnel and sealing the entrance.
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Re: What-If 0029: Spent Fuel Pool

Postby speising » Fri Jan 25, 2013 9:12 pm UTC

Well? It was there before for millions of years, and bothered nobody. Together with all the sand and plants.

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Re: What-If 0029: Spent Fuel Pool

Postby sardia » Fri Jan 25, 2013 9:46 pm UTC

speising wrote:Well? It was there before for millions of years, and bothered nobody. Together with all the sand and plants.

I believe the answer is similar to why a tree is good for the environment, but after I burn it for heat, it's bad for the environment. Physical changes have happened to the fuel that make it more dangerous than before.

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Re: What-If 0029: Spent Fuel Pool

Postby Fire Brns » Fri Jan 25, 2013 9:55 pm UTC

speising wrote:Well? It was there before for millions of years, and bothered nobody. Together with all the sand and plants.

Radioactives and heavy metals have bothered people by being a slow environmental poison. It just doesn't have the same psychological effect as a pool of glowing green goo.

Tobacco has a wonderful ability to pull heavy metals out of the ground. Uranium, a heavy metal, tends to be one of those that tobacco pulls up. Uranium decays into polonium which for the sake of simplicity will be described as pure cancer. I would be ignorant to assume that tobacco was the only plant that pulled toxins out of the ground. I know the body can mistake certain heavy metals for calcium and substitute them in bone tissue. I'm fairly sure uranium is one of those that can end up in bone.
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Re: What-If 0029: Spent Fuel Pool

Postby dreadengineer » Fri Jan 25, 2013 10:24 pm UTC

sardia wrote:
speising wrote:Well? It was there before for millions of years, and bothered nobody. Together with all the sand and plants.

I believe the answer is similar to why a tree is good for the environment, but after I burn it for heat, it's bad for the environment. Physical changes have happened to the fuel that make it more dangerous than before.


Correct; when a uranium nucleus fissions it doesn't disappear; it splits into two random-sized pieces according to a probability distribution. Some of those pieces will be stable atoms; others will be unstable and will eventually decay into stable atoms, releasing (typically) a gamma ray (i.e. radiation).

Those radioactive elements are why spent fuel is so radioactive, especially for the first few years after fission stops. By contrast, pure un-fissioned U-235 is safe to handle with your bare hands (this is important because it makes manufacturing U235 fuel rods a lot easier than thorium, for example).

So, spent fuel is much more radioactive than the original fuel because of the fission products. So it's a good idea to put it somewhere dry and non-geologically-active like Yucca mountain to decay, to be 100% sure particles won't leach into local groundwater somewhere. (That said, fission products don't actually leach that easily; the ancient natural nuclear reactor at Oklo still has its fission products in place.)


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