Why don't we drop medical waste and nuclear waste into active volcanoes?

[user101]

Why don't we drop medical waste and nuclear waste into active volcanoes? Aren't the temperatures in these volcaneous high enough to obliterate hazardous waste?

 

[theCandyman]

If they are active volcanoes, the volcano might erupt and the waste would be spread all over. It has been considered to drop the waste into the rifts between the tectonic plates, I don't think it's been done though.

 

[rocomath]

I remember that episode from Futurama in which a big spaceship was built to carry away the waste from Earth. Now that's a good idea :-]

 

[mathman]

I remember that episode from Futurama in which a big spaceship was built to carry away the waste from Earth. Now that's a good idea :-]

There are at least 2 problems.

1. It would have to be enormous.

2. In case of an accident on launching the fallout could be disasterous.

 

[vanesch]

Why don't we drop medical waste and nuclear waste into active volcanoes? Aren't the temperatures in these volcaneous high enough to obliterate hazardous waste?

For medical waste, this might do, but then a good stove might do too.
For nuclear waste, that's the last thing you want to do with it! The radioactive nature of the material is not altered by the "low" temperatures of a few thousand degrees, which only affect the chemical state and not the nuclear state. You'd need something much hotter to "incinerate" nuclear waste, of the order of a few million degrees at least (like the core of the sun).
The only thing a volcano would do, is to spread out quite effectively the radioactive material in the biosphere. Kind of "superchernobyl" style of exercise

The best thing you can do with nuclear waste is to keep it shielded away from the biosphere for a few hundreds / few thousands of years: it decays by itself. You want, at all price, to avoid it being spread massively around too early. That's why deep geological burrying is the "standard" solution to the nuclear waste problem. You want to keep it there for a few hundreds or a few thousands of years. Think of gas an oil and coal who have been confined for hundreds of millions of years in geological confines. A few thousand years shouldn't be such a problem. The last thing you want is to have it in an active volcano.

BTW, the fact that it decays by itself is one of the favorable properties of nuclear waste, which is not the case with certain kinds of chemical waste for instance. Heavy metals remain heavy metals for ever.

The next best thing to do with it, is to transform it actively. Although this can in principle be done, it is technologically an enormous challenge.

Sending nuclear waste in space is an idea that comes up regularly, but is basically flawed: the dangers of a failed launch are too great, the price is too high, etc... compared to the "standard" solution of deep geological burrying.

 

[DaveC426913]

Why don't we drop medical waste and nuclear waste into active volcanoes? Aren't the temperatures in these volcaneous high enough to obliterate hazardous waste?

medical waste: There is no need; simply buring the waste destroys it. And it would be very expensive to transport to the nearest volcano.

nuclear waste: Volcanos do not destroy nuclear waste.


[ EDIT ] I could have sworn Vanesch's post wasn't there when I posted mine...

 

[nanoWatt]

I thought that Uranium would reduce to Lead anyway. So just because it's producing less radiation doesn't make it safe.

BTW, the fact that it decays by itself is one of the favorable properties of nuclear waste, which is not the case with certain kinds of chemical waste for instance. Heavy metals remain heavy metals for ever.

 

[DaveC426913]

I thought that Uranium would reduce to Lead anyway. So just because it's producing less radiation doesn't make it safe.

Lead is dangerous of you ingest it. Ingesting materials from an active volcano might cause you other, more pressing problems.

 

[vanesch]

I thought that Uranium would reduce to Lead anyway. So just because it's producing less radiation doesn't make it safe.

This is true. Only, with "full nuclear incineration" (that is, by using a fast spectrum), the only genuine waste you have are fission products. Now, it is true that there are some genuinely chemically toxic materials in there, but the *amount* of it is very small as compared to the amount of directly generated chemically toxic materials by other processes.

The total fission energy content of 1 kg of uranium corresponds to the total combustion energy of 1500 ton of coal. So heavy metals present in coal on the level of the PPM are (without any retention) released into the biosphere at a greater quantity than those generated by fission for the same amount of energy.

Here, you find some interesting information:
http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html

For instance, it is estimated that from the burning of ~600 billion tons of coal worldwide in about 100 years, about 2 million tons of thorium and about 0.8 million tons of uranium will be released in the biosphere. In fact, the nuclear energy content of this material (which is present in coal, and is hence released in the ashes and smoke) is bigger than the combustion energy content!

In this http://www.osti.gov/bridge/servlets/purl/2069-ecN7fW/native/2069.PDF report, on p12, we find tentative compositions of some coal variants. Note that lead is present in the order of tens to almost hundred of ppm!

So we see that simply from one single source of heavy metal pollution of the biosphere, namely coal burning, we pollute already a few orders of magnitude more (for the same energy extraction) than its equivalent pollution by decay of radioactive waste *after its eventual full release to the biosphere* which is not intended.

 

[Andrew Mason]

This is true. Only, with "full nuclear incineration" (that is, by using a fast spectrum), the only genuine waste you have are fission products. Now, it is true that there are some genuinely chemically toxic materials in there, but the *amount* of it is very small as compared to the amount of directly generated chemically toxic materials by other processes.

The total fission energy content of 1 kg of uranium corresponds to the total combustion energy of 1500 ton of coal.

Closer to 2300 Tonnes - 2500 tons. See http://www.evworld.com/library/energy_numbers.pdf"

So we see that simply from one single source of heavy metal pollution of the biosphere, namely coal burning, we pollute already a few orders of magnitude more (for the same energy extraction) than its equivalent pollution by decay of radioactive waste *after its eventual full release to the biosphere* which is not intended.

Except that the radioactive elements released by coal burning - thorium and uranium mainly - are not very radioactive whereas fission products are very radioactive. The heavier non-fission products eg. Plutonium are also much more radioactive than U and Th.

Where nuclear is much more favourable is in the occupational health side: 6,000 miners die each year mining coal in China. Hundreds of thousands die prematurely each year from breathing the effects of burning coal. There is no perfect fuel but nuclear is better than coal on just about every issue.

AM

 

[vanesch]

Except that the radioactive elements released by coal burning - thorium and uranium mainly - are not very radioactive whereas fission products are very radioactive. The heavier non-fission products eg. Plutonium are also much more radioactive than U and Th.

Yes, but the point was the *chemical* toxicity of the (decayed) waste (in the long run), which doesn't go away.

 

[olgranpappy]

and besides, if we use the volcano for destroying medical/nuclear waste then what will we use to sacrafice our virgins?

 

[vanesch]

and besides, if we use the volcano for destroying medical/nuclear waste then what will we use to sacrafice our virgins?

I'll offer my services

 

[DaveC426913]

I'll offer my services

Do you have a particularly big caldera?

 

[ChrisLeslie]

Here, you find some interesting information:
http://www.ornl.gov/info/ornlreview/...t/colmain.html

The claims of this article, if true, make a compelling argument for nuclear over coal, or nuclear and coal over coal alone. Concern about the health effects of the U ad Th released in the environment is pointless if you consider that K-40 in coal is likely to be very much more in radioactivity, energy and gamma as well. Who ever appears to worry about K-40? Not many and despite the fact that we all reek in it.

 

[CaptainQuasar]

I've been thinking recently - what if we took nuclear waste, pulverized it (carefully, of course), and mixed it in with with concrete at a dilution that makes it no more radioactive than uranium ore. Then take the concrete and use it to fill in played-out mines (not necessarily uranium mines, just any mine at all, selected for not being under the water table, etc.) Would we end up with any dangers greater than what is naturally present in the environment anyway?

⚛​

 

[binzing]

Why does your title not match your actual post?

 

[CaptainQuasar]

I think you missed that we're on the 2^nd page, binzing.

⚛​

 

[ChrisLeslie]

I've been thinking recently - what if we took nuclear waste, pulverized it (carefully, of course), and mixed it in with with concrete at a dilution that makes it no more radioactive than uranium ore. Then take the concrete and use it to fill in played-out mines (not necessarily uranium mines, just any mine at all, selected for not being under the water table, etc.) Would we end up with any dangers greater than what is naturally present in the environment anyway?

Does anybody have opinions on the pros and cons of concentrating and burying waste, as above, compared to spreading it evenly around the globe via the stratosphere?

 

[DaveC426913]

Does anybody have opinions on the pros and cons of concentrating and burying waste, as above, compared to spreading it evenly around the globe via the stratosphere?

It's not that we can't dispose of it, it's that we can't dispose of it economically.

 

[theCandyman]

Or politically. The main thing holding back the start of construction of a depository is public opnion. The tax paid on energy generated by nuclear energy for the past couple decades should cover the cost.

 

[DaveC426913]

I was going to mention safety, but that is ultimately tied up with cost and politics as well.

Who will let somoene transport waste through their own backyard, and how much extra will it cost to guarantee safety?

 

[Count Iblis]

Why don't we drop medical waste and nuclear waste into active volcanoes? Aren't the temperatures in these volcaneous high enough to obliterate hazardous waste?

As pointed out by others, the temperatures are not high enough to destroy radioactive elements. The energy needed to break up a nucleus is of the order of 100 MeV or more, so the temperature must also be in the 100 MeV range = 10^(12) Kelvin range

And if we want to transport the radioactive waste into the Earth, then you are better off using subduction zones, not the places where things move upward

 

[Count Iblis]

Does anybody have opinions on the pros and cons of concentrating and burying waste, as above, compared to spreading it evenly around the globe via the stratosphere?

I think we should concentrate it and then use it as a heat source. Suppose you extract 1000 kg of caesium-137 and make a compound (pure caesium metal is extremely reactive). Then this compound will be very hot because of the radioactive decay of the caesium. You can then make a heat exchanger out of this material and e.g. use it to heat water. And it will still yield 50% of the original power output 30 years later. If that is not good enough anymore, you just recycle the radioactive cs-137 from the old system for use in a new water heating system.