This is a silly question, I admit, but this thread made me think of this:
What would happen if we disposed of spent nuclear fuel by dropping it into lava? Like at Volcanoes National Park?
Wouldnt that just create a buncg of irradiated rock?
I suspect that the next volcanic eruption would spread irradiated ash over the countryside.
Can’t find the thread, but it and similar questions have been asked before.
Not a good idea. Lava doesn’t actually destroy nuclear fuel. It doesn’t burn to nothing. Even if it disintegrates, you’re left with the same amount of radioactive stuff, now in particulate form.
So, all we’d be doing is spreading nuclear fuel around wherever the lava ends up. Worst case, there’s a volcanic explosion and we’ve just put tons of nuclear waste into the atmosphere to be distributed around the world.
Xenu? Is that you?
Seriously: radioactive lava is unlikely to ever be a good thing.
You’d get radioactive lava and rocks throughout the park. The stuff under a volcano isn’t (usually) going to sink back under the earth’s crust. I suppose some of it might melt and mix into a magma chamber, so that you’d have a lot of moderately radioactive lava instead of a small amount of highly radioactive waste. Maybe some of it would be contained under ground for long periods of time, but I’d bet that you’d just turn the whole area around the volcano into a radioactive waste site.
Now, there are half-serious proposals to dispose of waste in subduction zones where one part of the crust is sinking under another. Over geological time scales, the waste would be melted diluted through huge areas of the mantle. But on human time scales such schemes would pretty much have casks of waste sitting in geologically unstable oceanic trenches for thousands of years. Would you trust those casks to survive that long?
Depends a bit on the waste - but you could just maybe get rid of something this way. Typical fuel rods are clad in zirconium alloy. Zirconium has a melting point higher than almost all magmas. So, if you were very brave, you could drop your spent fuel rods into a magma chamber, and hope that the reasonably dense rods (full of uranium dioxide - density 10+) would sink through the magma, and with luck would sink far enough that by the time the cladding was breached they would be way past any chance of returning. The uranium dioxide pellets have an even higher melting point, and won’t be a problem, but the evil stuff - the fission products in the rods will be. Once the rod is breached it will leak radioactive isotopes of caesium, strontium, xenon, and all sorts of other goodies. It is these that make the fuel rods waste. Unless the rods make it pretty deep, this stuff will be coming back again soon. Trouble is that magma is reasonably viscous, and gets more so as you go down. It is going to take a very long time for something to sink far enough - years possibly - and any up-welling of the magma may overtake the sinking.
I blame TV. If you zap something, it is completely destroyed. Nothing left.
Doesn’t work like that in real life.
I’m going to file a Class Action suit against TV for Willful Spreading of Ignorance.
The problem with hoping that casks of radioactive waste will sink is that volcanoes don’t have large-enough spaces for something to sink through. There’s not a giant open well or something like that. The lava is moving through (in fact, often “forcing open” is the better term) small cracks the rock. Casks of nuclear waste won’t sink through that any better than an iron pellet will sink through a kitchen sponge.
If you actually had a wide open, unobstructed path down to a magma chamber, you’d have high-pressure lava spewing out and nothing would sink through that regardless of density, and once the pressures equalized, you’d have a collapse that would block up the opening and put you right back to tiny cracks.
I blame The Lord of the Rings. It worked for Frodo.
Yeah, but I wouldn’t have wanted to be living in Mordor when it happenned.
Isn’t that pretty much the origin story for Godzilla?
I appreciate the answers. I don’t have anything to add, but I didn’t want to look like a drive-by OP.
This leads me to a similar question:
Understanding that right now it is probably cost prohibitive, but assuming the cost factor could be mitigated, would shooting nuclear waste into the Sun actually be the best way to dispose of the material?
A few questions:
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There are no issues with our technological ability to do this correct?
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Would the Sun actually completely destroy the materials or otherwise render them inert?
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Any chance that the material could/would come back to harm us in the form of the very rays that warm our planet?
It takes a lot of fuel to shoot something into the sun (more than it takes to shoot it out of the solar system, according to a recent thread which I couldn’t find, but here’s one that discusses the same sorts of stuff, including waste being fired into black holes and the sun). And in the meantime you have a load of nuclear waste sitting on top of all that fuel. If something goes wrong, the thing might explode while the nuclear waste is still in the atmosphere, and that would be bad.
In fiction, though, Niven had at least one Known Space story where they got rid of waste by depositing it on the moon, the thinking being that future generations might actually be able to use today’s waste as fuel.
Exactly- what would likely happen is that your nicely concentrated radioactive waste would get distributed in everything in the Kilauea magma chamber (I’m assuming that’s the volcano being discussed at the Volcanoes Natl. Park), and then on the next major eruption, you’d basically end up with radioactive lava flows, radioactive Pele’s Tears and Hair, and probably at some point, radioactive steam when the radioactive lava meets the sea.
Not a good plan, really. Far better to encapsulate it well, weight it seriously, and drop it into a subduction zone, if you ask me.
What temperature is necessary to render nuclear waste inert?
This was the Slate Explainer column’s 2007 question of the year.
(Their answer was the same: Bad stuff would just come right out again.)
In addition to what has already been mentioned (radioactive steam, ash, etc) some if it will probably end up getting burped up and forming part of the new land that always forms around volcanoes. Then in a few hundred years erosion will start wearing it away, carrying stuff that is still radioactive into the ground water and causing all kinds of problems.
Nothing reasonable. Even if you melt it, it remains radioactive and dangerous. At Chernobyl, for example, a big chunk of the core melted and essentially became lava, flowing down out of the core. It solidified as it cooled forming what they call the “elephant’s foot” structure., which is still highly radioactive. Completely melting it did not render it inert.
One does not simply carry nuclear waste into Mordor.
It’s actually easy to understand why once you understand how orbits work.
The classic thought experiment is throwing a baseball on Earth. If you just drop it, and don’t impart any momentum of your own to it, it will fall straight down. If you throw it at a low speed, and only impart a little momentum, it will go a short distance before hitting the ground, because momentum is conserved: The ball always takes the shortest path it’s allowed to take*, and with the momentum you gave it, the shortest path involves going forwards a little while. As you add more and more momentum, it has to go forwards a greater and greater distance, until its forwards path is enough to take it completely around the world. Without anything to slow it down, like an atmosphere, it never stops falling, because it never hits what it’s falling towards, but, at the same time, it doesn’t have enough momentum to keep going in a straight line forever. That’s an orbit: A balancing act between gravity, which keeps it tethered, and momentum, which keeps it moving.
*(This is called the ‘Path of Least Action’, and it shows up a lot when you study quantum physics. It’s part of the fundamental fabric of reality.)
So. The Earth is falling towards the Sun, but it has enough momentum at right-angles to the path into the Sun to keep it orbiting. This means everything on Earth, and everything that’s orbiting Earth, has (pretty much) the same momentum in the same direction. Therefore, getting something from the Earth into the Sun requires taking away the momentum it has from being on something that’s orbiting the Sun. That’s quite a lot of momentum, at least in our case, and the only way to get rid of it without an atmosphere (and, remember, Earth’s atmosphere has the same momentum Earth itself does) is to burn fuel in engines pointing the opposite direction of the orbit. It’s easier to get to Mars, for example, because you can use the momentum you got from Earth to your advantage and build on it to get into an orbit farther out than Earth’s, one that intersects Mars’ orbit.