Dropping spent nuclear fuel into lava

Factual Questions
21

There is essentially no temperature that will render it inert.

Normal chemical toxins are dangerous because of chemical reactions and can frequently be made safe just by breaking molecular bonds. These molecular bonds (made between the electrons of each atom/molecule) break pretty easily; lava would be hot enough to dispose of most toxins.

But radioactivity is not a property of molecular bonds because it depends on the nucleus of the atom (hence the term nuclear). Uranium at any temperature is still uranium and still radioactive, even in the core of the sun.

To make a radioactive element inert means changing the nucleus of the atom in some way such as fission, fusion, or radioactive decay processes like beta particle, alpha particle and gamma ray emissions. The radioactive decay happens naturally and can’t be stopped, but it can take millions or billions of years for some isotopes to become inert this way. We don’t have any way to do fusion or fission of atoms that doesn’t produce more radioactivity than we’re trying to get rid of, and that’s why long-term storage of radioactive substances is our only strategy right now.

22

One might as well ask how we could permanently and definitively get rid of all this useless gold we have lying around. Maybe you could figure out some way to do it, but why would you want to? The only difference is that gold is only valuable because some people like it, while nuclear waste is inherently useful.

23

For the latter two questions, the Sun wouldn’t destroy them, except for molecular compounds (uranium dioxide -> uranium and oxygen) but that wouldn’t matter, nor would it make sunlight radioactive, especially when you consider that you could drop the entire Earth into the Sun (which is about a million times larger) and it wouldn’t notice it any more than an elephant would a gnat. Also, sunlight already originates as gamma rays (the most dangerous kind of nuclear radiation), which gradually lose energy over thousands of years until they finally escape (that said, sunlight contains gamma rays that escape).

24

The sun’s radioactive?! RUN!!!

25

that would explain the modified e coli strains found in some magma tests

26

Question: IF you could get our radioactive trash dropped onto the Sun, isn’t it hot enough there to break down said trash into non-atomic plasma?

27

What do you mean by “non-atomic plasma”? If you meant to say “monatomic”, that is to say, the molecules broken up into individual atoms, then sure. But that doesn’t make any difference for radioactive material. If you actually did mean “non-atomic”, i.e., not made of atoms, that requires absolutely friggin’ absurd temperatures, which haven’t been found anywhere in nature since the time of the Big Bang.

28

No, or as far as I know; atoms will break down in the sense that they lose their electrons but the nuclei stay intact, and it is the latter that determines what kind of atom/ion you have, similar to what happens in chemical bonds (a uranium atom, uranium ion and bare uranium nucleus are all still uranium). Maybe if you heated up an atomic nucleus enough it will decompose into protons and neutrons, then into quarks (as in neutron stars (electrons and protons turn into neutrons), and quark stars, if the latter exist, but it is mainly due to extreme pressure).

29

Aha, so all we have to do is drop enough nuclear waste into the sun so that it turns into a neutron star! Another 0.44 solar masses should do it, right? We’d better get to work.

And Derleth, that was a great explanation of orbits and why it takes more energy to launch something from earth into the sun than it takes to launch it out of the solar system entirely.

30

Just send it in to the nearest black hole. It’ll be gone forever, that way.

No radiation can escape a black hole (except hawkings radiation), so even though it may still “exist” in some sense (though probably not once it reaches the singularity at the center), for all intents and purposes, it’s a ‘perfect’ way to dispose of it.

31

Perhaps a foolish question…but why not use nuclear fuel waste to heat process water? It could be insulated by a heat exchanger, and you coulod get limitless hot water…and not worry about where to bury the stuff. A lot of energy is used to heat water-why not utilize the stuff for this?

32

Yes, you could use radioactive material to generate heat. The problem is that your radioisotopes are generating dangerously high energy photons as they decay. So yeah, you could have a lump of plutonium sitting on your kitchen countertop, and you could boil water for your morning coffe with it. But it would be constantly generating gamma rays and xrays, and those would go zooming off into your kitchen and into your body. Not good.

Any source of radionuclides concentrated enough to generate a useful amount of heat is going to be much too dangerous to actually use.

However, note that lots of space probes use radioactive isotopes to generate heat to create electricity. Because they’re in deep space they don’t have to worry about the radiation affecting people and animals, just the modules on the space probe itself.

Of course, launching nuclear materials into space is a really bad idea. Space launch technology isn’t exactly foolproof, and every so often things explode, or go the wrong direction. Congratulations, you’ve just spread nuclear waste all over Florida.

There are much much cheaper ways of dealing with nuclear waste. Like, digging a deep hole in an area with no ground water, and piling it in there. That’s what the Yucca Mountain facility was supposed to be. Except Nevada got mad that they had to accept the nuclear waste from all over the country. The other problem is transportation of the waste from all the generating sites all over the country to the repository. Trains are a lot safer than rockets, but we still have massive train wrecks every so often, often causing nasty chemical releases.

And so we have the situation we have now, which is where nuclear sites mostly retain the nuclear waste they generate on site. This has the advantage of reducing transportation, and the nuclear site is already a nuclear site. The problem is that a lot of sites aren’t really suited for long term sequestration of nuclear materials, due to extensive groundwater, potential for earthquakes or floods, and so on.

But the notion that nuclear waste is so dangerous that we have to remove it from the planet to be safe is just silly. Low level waste will be dangerous for thousands of years, but that’s because it is decaying really slowly. The really dangerous isotopes fission really quickly, that’s what makes them dangerous.