How should we get rid of Nuclear Waste?

[Floppster]

The Sun is huge.

<More simple math>

Okay, didn't put things in perspective

[glacierre]

During our history of nuclear energy usage we've produced just 70k metric tons of the stuff. Going by average density this is about 15 Olympic swimming pools of waste during our entire history. We'll probably switch to a fusion based energy system in a century or 2. So fission only has to carry us for a measly 2 centuries. The resulting waste is considerable, but it really is peanuts in terms of volume. Dump it, somewhere safe. We can always dig it back up a few centuries later and use our scarcity free economy to get rid of it completely.

I find the attitude of "I don't know how to solve this problem that I am creating, but instead of stopping to make more trouble, I will kick it to the future and let them deal with it" completely short sighted and appalling. Moreover, "we probably" and "we will" are not synonyms.

One of the main ways of preventing proliferation of weapons grade material is to make sure that it is contaminated with something particularly nasty. For example, spent nuclear fuel contains some plutonium-239, which is only very lightly radioactive, and can be used to make bombs fairly easily. However, it is usually contaminated with a lot of other really horrible things, that will kill you pretty quickly if you get too close, so the only way of getting at that plutonium is to have some really advanced processing techniques only available to very rich governments. This keeps the plutonium out of the hands of regular Joes and crazy people.

NOOOPE. This does nothing to prevent a cheap, easy and "extra nasty" (thanks to your idea) dirty bomb. You just need to get the stuff, grind it in fine dust, load it in a bucket and use conventional explosives.

Crazy people and terrorists do not need to know nuclear physics to completely disrupt life in an average sized city, just basic pyrotechnics is more than enough.

About this topic, I found this documentary very, very good http://www.imdb.com/title/tt1194612/

We should all keep in mind the "quality" of the buildings executed by government contractors in the last century and wonder how realistic is to expect the lowest bidder to build something for the next 10.000 years.

Edited April 27, 2014 by glacierre

[cantab]

From what I've read, the deposits of uranium and such in Earth's crust are part of its original formation rather than from later bombardment. They are (probably) upwellings from deep below caused by turbulence during the asteriod bombardment period. The crust hardened before they sank again.

I don't believe they are. Uranium ores do tend to be found in old continental rocks, but even those were formed some time after the Earth formed and solidified (and got clonked by Theia), and there are some in much younger rocks.

Indeed, while it's relatively rare in the crust by virtue of being relatively rare in the universe, Uranium's not one of the siderophile elements that preferentially goes into the iron core, but readily binds with oxygen into minerals. IIRC it's more abundant in the crust than in the deep Earth, and most of the radioactive heating within the Earth happens around the core-mantle boundary, while the heat flow from the core is mainly driven by latent heat released when from the iron freezing.

(See http://en.wikipedia.org/wiki/Goldschmidt_classification for a fuller discussion)

[peadar1987]

NOOOPE. This does nothing to prevent a cheap, easy and "extra nasty" (thanks to your idea) dirty bomb. You just need to get the stuff, grind it in fine dust, load it in a bucket and use conventional explosives.

Not my idea, it's what is actually considered when talking about fuel cycles.

And grinding it up isn't particularly easy when it will kill you in a few seconds just from being near it.

And even if you do that, with 20kg of nuclear waste, you can contaminate maybe a few square kilometres of a city. With 20kg of weapons grade plutonium, you could level that same city. Big difference!

I always think terrorists are far too focused on large-scale, spectacular attacks. Every now and again you hear of a cell of 10 or so terrorists arrested for plotting to blow up a landmark or airliner. How much more chaos would they have caused if each of them had just bought a handgun and ammunition, and opened fire in a crowded area. It doesn't bear thinking about, so I suppose we're quite lucky that most terrorists are basically morons.

Crazy people and terrorists do not need to know nuclear physics to completely disrupt life in an average sized city, just basic pyrotechnics is more than enough.

About this topic, I found this documentary very, very good http://www.imdb.com/title/tt1194612/

We should all keep in mind the "quality" of the buildings executed by government contractors in the last century and wonder how realistic is to expect the lowest bidder to build something for the next 10.000 years.

Too right. It's an issue that's too important to try and cut corners to save costs. Although, as per my previous post, after only a few hundred years, it will be reasonably safe to be around the waste, so long as you don't get any of it in or on your body for long periods of time, as most remaining radiation will be beta particles and soft X-rays.

Edited April 27, 2014 by peadar1987

[Beowolf]

I don't believe they are. Uranium ores do tend to be found in old continental rocks, but even those were formed some time after the Earth formed and solidified (and got clonked by Theia), and there are some in much younger rocks.

IIRC it's more abundant in the crust than in the deep Earth, and most of the radioactive heating within the Earth happens around the core-mantle boundary, while the heat flow from the core is mainly driven by latent heat released when from the iron freezing.

Interesting, and thanks for expanding my knowledge. While this is far outside my field, I will say that I've read multiple articles in the past decade or so that said we used to think the molten core was from latent heat, but now believe it's radioactive decay. But I never tried to validate those statements like I would in a field I understood.

Frankly I'm hoping I'm the one who's wrong and we'll find usable deposits all over.

[cantab]

Interesting, and thanks for expanding my knowledge. While this is far outside my field, I will say that I've read multiple articles in the past decade or so that said we used to think the molten core was from latent heat, but now believe it's radioactive decay.

If that's a recent development then you may be correct, I haven't been keeping in touch with earth sciences as much as I used to.

As for uranium more generally, the BGS has a pamphlet on it that seems pretty comprehensive, https://www.bgs.ac.uk/downloads/start.cfm?id=1409 though I only skimmed it myself.

[Dwayne_Knight]

A lot of nuclear waste can be re-processed and used as fuel. Whatever can be re-used, should be.

As for the rest, it should be buried in a geologically stable place, like Australia. Or perhaps get it into a subduction plate somehow.

I like the idea of burying it deep in a subduction zone so it eventually gets dumped into our core and in some tiny way helps with our magnetosphere.

I'm glad someone mentioned it.

[Dwayne_Knight]

That sounds really implausible. The steel ball is submerged in 4 celcius water, that's a ridiculously good heatsink. And steel is a pretty good heat conductor. So there's no way that ball is going to get hot enough to melt the rock.

What if they were buried would the stone provide enough insulation?

[Spanier]

Uuuh, I had long and exhausting arguments about this topic.

So here some facts:

1. There are 300.000 tons of HLW worldwide, and each year we get 12.000 additional tons
   
2. Deep geological repositories for current HLW must be save for at least 300.000 years (*)
   
3. Current plans for disposal sites call for the waste being retrievable, so deep boreholes aren't considered
   
4. Dumping the waste in the oceans can have unpredictable impact on the local (!) flora/fauna, and has been practiced in the North Sea
   
5. It takes about 600.000 years for the fast-fission products of Pu239 to reach the same level of radiotoxicity of 300.000a old radioactive waste from current reactors
   
6. It takes about 1.200.000 years for the fast-fission products of U233 to reach the same level of radiotoxicity of 300.000a old radioactive waste from current reactors
   
7. Efficient fusion reactors aren't feasible with current technology, and even if we gain that in near future, it's very likely, it's way too expensive to be considered as a suitable power source
   

(*) At least that's considered as "long enough" in Germany, even by the supporters of nuclear power plants

The last two facts, I calculated myself, radiotoxicity is measured in Sv/kg. (Links: http://goo.gl/Wp85no http://goo.gl/pGILrz)

So even if a deep borehole might be the safest option, all countries around the world producing this stuff, currently consider, that future generations might have a brilliant idea about what to do with that highly toxic waste.

Edited April 28, 2014 by Spanier

[glacierre]

So even if a deep borehole might be the safest option, all countries around the world producing this stuff, currently consider, that future generations might have a brilliant idea about what to do with that highly toxic waste.

Put it in a time machine and set the dial to year 2000. With a note "Dear ancestors, we think this is yours. BTW we found the solution for this stuff... Enjoy"

[theend3r]

So even if a deep borehole might be the safest option, all countries around the world producing this stuff, currently consider, that future generations might have a brilliant idea about what to do with that highly toxic waste.

Coal powerplants release much more radioactivity into enviroment than all this waste together. Actually, properly handled, nuclear power plants don't release anything at all (except water).

Some food for thought: http://www.scientificamerican.com/article/coal-ash-is-more-radioactive-than-nuclear-waste/

[Spanier]

Coal powerplants release much more radioactivity into enviroment than all this waste together. Actually, properly handled, nuclear power plants don't release anything at all (except water).

Some food for thought: http://www.scientificamerican.com/article/coal-ash-is-more-radioactive-than-nuclear-waste/

Yeah, that's right, but it's not nearly that concentrated like in HLW. Coal ash is about as radioactiv as the waste, thats created at the Uranium mines, the tailings of these are compareable to lignite-ash, or even more dangerous.

Put it in a time machine and set the dial to year 2000. With a note "Dear ancestors, we think this is yours. BTW we found the solution for this stuff... Enjoy"

Appart from the time-machine-thingie, it sounds totally plausible.

[lajoswinkler]

Coal powerplants release much more radioactivity into enviroment than all this waste together. Actually, properly handled, nuclear power plants don't release anything at all (except water).

Some food for thought: http://www.scientificamerican.com/article/coal-ash-is-more-radioactive-than-nuclear-waste/

Actually, they do release some stuff, but the amounts of it, and the radioactivity of such things are very low, so that the total amount doesn't exceed normal, background levels. It's gases like tritium which are reclaimed from the irradiated water from the primary loop. They keep it in tanks for a while, then dilute it and release it through certain stacks (not the cooling towers).

Additionally, you have to consider the total life cycle, even the mining. Uranium mining is problematic because the companies easily break the laws. Local pollution occurs as the ore is milled in inadequate conditions, just like with most other metal ore mines.