How should we get rid of Nuclear Waste?

[falofonos]

There are several treaties prohibiting the dumping of nuclear waste at sea which would eliminate the geological subduction plan as well as the deep ocean dump.

Same applies to firing the stuff into space.

Due to the statistically insignificant threat of terrorists hijacking a shipment of the stuff and more significant threat of a traffic accident, transportation is a problem so why not bury it next to the reactor. What could possibly go wrong? Aside from some sort of china syndrome thingy?

[Javster]

Currently, I've heard the volume of a swimming pool/reactor is enough to store it all.

[robopilot99]

My solution:

Find a desert

Dig a hole

Dump your nuclear stuufs in

Fill the hole with concrete

Put up a fence with DANGER RADIOACTIVE! Signs all over it

[peadar1987]

There are several treaties prohibiting the dumping of nuclear waste at sea which would eliminate the geological subduction plan as well as the deep ocean dump.

Same applies to firing the stuff into space.

Due to the statistically insignificant threat of terrorists hijacking a shipment of the stuff and more significant threat of a traffic accident, transportation is a problem so why not bury it next to the reactor. What could possibly go wrong? Aside from some sort of china syndrome thingy?

The main threat is it leaks into the groundwater, which can transport radioactivity to somewhere it can get at people, which is not good.

Road accidents are actually not really a threat, the containers are unbelievably sturdy:

I've seen the actual fuel flask they used for that test, it was outside the plant where I worked. The only damage was a few bent cooling fins. The train was vaporised

[Galacticruler]

confirm there is no life on it, and dump it on Mercury

[makinyashikino]

confirm there is no life on it, and dump it on Mercury

If anything could survive on MERCURY, a vacuum with no atmosphere and the insane surface temperatures, I think they could survive a little nuclear waste.

[NERVAfan]

You say "dump it somewhere safe" but what is safe? It has to last for millions of years

I am deeply skeptical of this. Things get less radioactive over time... isotopes with higher half-life decay faster... so most of the REALLY nasty stuff is going to be gone long before "millions of years". Sure, it will still be radioactive, but...

The chances of it actually harming anyone if it's put somewhere relatively inaccessible (say Yucca Mountain) is just not high enough to be worth worrying about.

[Seret]

why not bury it next to the reactor.

Nuclear power plants are often built next to bodies of water, to give them access to coolant.

[78stonewobble]

I'd say go with the ocean trenches at in a subduction zone. Seems to me to be the safest place free from any large scale human interaction. 2nd option would be a geologically stable desert something buried in rocks.

[peadar1987]

After about 10,000 years, nuclear fuel is a million times less radioactive than when it came out of the reactor.

The surface dose rate of spent nuclear fuel just after leaving the reactor is about 250,000 Sv/hr. It takes about 5 Sv to give you fatal and irrevocable radiation poisoning in most cases, which means if you touched a nuclear fuel rod just after it left the reactor, as well as burning yourself horribly from the heat, you'd have fatal radiation poisoning in just under a tenth of a second.

After 10,000 years, the activity will be down to about 0.25 Sv/hr, and that's only when you're actually touching the sample. That's enough to significantly increase your risk of cancer, and even kill you, if you decide to build a chair out of it or something. However, at this stage, the radiation emitted is mostly beta particles, and soft Brehmstrahlung X-Rays, which tail off rapidly as they pass through matter (like the air).

Beta particles are generally accepted to be stopped by 15-20cm of air (or by human skin), so if you don't lick the spent fuel you'll be fine, even if you keep it in the corner of your living room.

The main health issue associated with beta- and alpha- emitters is if they are ingested, absorbed, or inhaled into the body. If this happens, they can sit in your tissues happily emitting radiation at close range with no air or anything to shield you from it, so basically we're left again with the main issue being stopping the stuff from getting into the water.

At this stage, the main contributor to radiation in the fuel is Technetium-99, which has a half-life of just over 200,000 years, so after this, the level of radiation is going to tail off very slowly indeed.

An interesting side note I found while researching this post:

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.

However, after a few tens of thousands of years, the nasty stuff will have decayed, leaving the plutonium behind in a form that can essentially just be dug up out of the ground and shaped into a bomb core with only minimal reprocessing, which is a pretty scary thought!

[Nuke]

thats one of the reasons i mentioned subduction zones. geology takes a really long time to do its thing. something that gets pulled along with a bit of subducting crust is going to take a very long time to ever see the light of day again, by which time its either been thoroughly mixed up with other material, or has decayed sufficiently to be harmless. its proibly going to be the best bet to find a spot far away from nearby volcanoes to increase the amount of time it would need to travel there, which by geological scales is a really really long time.

[bsalis]

Why not dump it in the Sarcophagus before they roll the New Safe Confinement over it?

Area is already screwed. Will save you the effort of putting up all the radiation hazard signs too.

[Seret]

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.

Which is why reprocessing is so controversial.

[Accelerando]

Let's dump it on the surface of Enceladus. Maybe we can finally reach that ocean.

[Nuke]

using reactors with online reprocessing is better for non proliferation. you reprocess smaller amounts and immediately put it back into the reactor, it gets burned up right away rather than just put in inventory, where it can sit until somebody steals it. lftr has a good way of doing this, i even seen a canadian solid core reactor design that let you extract fuel pellets while the reactor is running, reprocess them, and load them back at the other end.

[NERVAfan]

However, after a few tens of thousands of years, the nasty stuff will have decayed, leaving the plutonium behind in a form that can essentially just be dug up out of the ground and shaped into a bomb core with only minimal reprocessing, which is a pretty scary thought!

I think it is pretty unlikely to matter given that that mattering would imply a technological level very close to ours. A low-tech society (even say 19th century level) wouldn't know how to use it, and a high-tech society (say, one with antimatter manufacturing ... or even just lots of orbital industry and thus the easy ability to make orbital kinetic strikes/nudge asteroids) would have widespread really dangerous stuff to the point that they likely wouldn't worry as much about nuclear proliferation as we do... in the same way that ammonium nitrate is widely used in industry today despite being really explosive.

[PyroDesu]

using reactors with online reprocessing is better for non proliferation. you reprocess smaller amounts and immediately put it back into the reactor, it gets burned up right away rather than just put in inventory, where it can sit until somebody steals it. lftr has a good way of doing this, i even seen a canadian solid core reactor design that let you extract fuel pellets while the reactor is running, reprocess them, and load them back at the other end.

The CANDU reactor (second design referred to) can even burn the various actinides. And even some unreprocessed fuel from other types of reactors, as I recall.

[architeuthis]

As far as I know there is no way to completely eliminate waste. But we could pretty dramatically reduce the the volume, and mitigate the environmental impacts, of high-level waste though transitioning commercial power to low-waste generation and a combination of geological repositories, reprocessing, and integral fast neutron reactors.

[YourEverydayWaffle]

I am a fan of the Traveling wave reactor.

http://en.wikipedia.org/wiki/Traveling_wave_reactor

Finally, somebody who knows what a TWR is. Yeah, they're great

[YourEverydayWaffle]

The current method, storing it in waterproof salt caverns, but if sending things to orbit was cheaper, I'd say a graveyard orbit would be the best option.

[YourEverydayWaffle]

The CANDU reactor (second design referred to) can even burn the various actinides. And even some unreprocessed fuel from other types of reactors, as I recall.

You're right, the CANDU can use deuterium, thorium, some types of used waste, uranium, plutonium, you name it. They're are already a couple of them running, and so far, the results have been very good.

[Duxwing]

I got the following idea from a science magazine: pile still-hot nuclear waste into a steel bathysphere and lower it into a subduction zone, where the waste's heat will melt the rock, which will eventually bury the fuel.

-Duxwing

[Ralathon]

I got the following idea from a science magazine: pile still-hot nuclear waste into a steel bathysphere and lower it into a subduction zone, where the waste's heat will melt the rock, which will eventually bury the fuel.

-Duxwing

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.

[Sophistry]

Crashing something into the sun is bloody difficult, and a highly overpriced, wasteful, inefficient way to deal with it.

Sounds like we need to outsource the problem to some Kerbals!

[peadar1987]

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.

Plus the rock will probably melt at a higher temperature than any metallic fuel elements, and a good deal of the ceramics as well. And it's very hard to melt your way down through something, you have to melt a lot to have a sufficient volume of liquid to make anything sink.