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Author Topic: Can we "export" fission waste ?  (Read 8318 times)

Offline Geezer

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Can we "export" fission waste ?
« on: 20/12/2010 02:59:35 »
There has been some discussion about disposing of nuclear waste that is a byproduct of fission reactors by launching it into the Sun.

What does the energy balance look like? If we were to do this, would we expend more, or less energy than the energy we obtained from the reactor?


 

Offline William Myres

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Can we "export" fission waste ?
« Reply #1 on: 20/12/2010 03:28:23 »
Dear Geezer, Multiple rockets to the sun must overcome the 30 kilometers per second speed with loads of tens of thousands of tons. They would have to do it with gravitational assist from the Earth and Venus, taking years per voyage. I really wouldn't want thousands of those rockets up there on near collision courses with the Earth.
 

SteveFish

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Can we "export" fission waste ?
« Reply #2 on: 20/12/2010 03:40:22 »
Also, what about a launch failure. The best scheme I have heard about for the nuclear waste problem has been promoted by James Hanson (global warming guy) and others. There are several new nuclear reactor types that are being studied that are referred to as Generation 4 if anybody wants to research this. There is a pretty good nontechnical piece on Wikipedia. Some of these reactors can run on the waste from the older reactors and the final products have half lives in the hundreds of years instead of the multiple thousands of years of the current waste. So, if the reactors can be made safe they could actually use up the waste while generating electricity. I don't know enough about this to comment further. Check it out.
« Last Edit: 20/12/2010 03:42:59 by SteveFish »
 

Offline Geezer

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Can we "export" fission waste ?
« Reply #3 on: 20/12/2010 04:33:42 »
Thanks William and Steve!

I'm sure there are many potential issues, and there are probably many alternatives to such a scheme, but I thought it would be interesting to try to understand if there was even a net energy gain associated with it. If the net energy gain is negative, then it's probably not even worth considering.

In it's most simplistic form, the question concerns energy versus the mass required to obtain that energy. That's why I posted it in the Physics forum.
 
 

Offline syhprum

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Can we "export" fission waste ?
« Reply #4 on: 20/12/2010 05:58:08 »
I cannot understand the obsession with the waste from fission reactors, coal fired power stations dump far more radioactivity into the environment and the deaths caused by coal mining are at least a thousand times as many as those caused by nuclear power station mishaps.
The present arrangements for storing nuclear waste are adequate and the only barriers for long term underground storage are only political.
 

Offline Geezer

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Can we "export" fission waste ?
« Reply #5 on: 20/12/2010 06:13:03 »
I cannot understand the obsession with the waste from fission reactors, coal fired power stations dump far more radioactivity into the environment and the deaths caused by coal mining are at least a thousand times as many as those caused by nuclear power station mishaps.
The present arrangements for storing nuclear waste are adequate and the only barriers for long term underground storage are only political.

I confess my question had a "slightly" political overtone. If the energy cost of dumping the byproducts into the Sun is small, why would we not do it?

So, (physicists) what's the energy balance?
 

Offline peppercorn

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Can we "export" fission waste ?
« Reply #6 on: 20/12/2010 09:54:09 »
Here's a thought: What would be the longterm effect of dropping it (lightly encased) into the deepest parts of the worlds oceans?
 

Offline Mazurka

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Can we "export" fission waste ?
« Reply #7 on: 20/12/2010 13:40:58 »
Here's a thought: What would be the longterm effect of dropping it (lightly encased) into the deepest parts of the worlds oceans?
Although not precisely an answer to your question, there has been some research carried out into the dumping at sea - in the 50's and early 60's the US dumped drums containing radioactive materials at a couple of deepwater sites.  In the 70's there was some investigation of the "2800m" site  which is approximately 200km off the east coast.  The drums dumped there were mainly intact and the geochemistry of the sediment was investigated to see if the cation exchange capacity of the clay minerals in the sediment would be sufficient to lock up any leaks.  I understand that the conclusion was that it might work, but the sedimentation rate was too low to cover the drums.
As a consequence there was some research into the possibillity of dumping drums into "turbidty currents" that run down the continental slope at 60mph, thus encasing the waste into turbidite depoists.  However, these are too unpredicatble.

However, I guess the biggest obstacle to such dumping would be international treaty - it was banned by the London Convention in 1993...       
 

SteveFish

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Can we "export" fission waste ?
« Reply #8 on: 20/12/2010 15:23:59 »
Geezer, I am pretty sure there is much more energy made by power plants than would be expended by any number of waste disposal schemes, including launching into the sun, but the energy balance is not important. What is important is the cost. The real cost of current nuclear reactors is already so high that increasing this is unacceptable (and they told us it would be too cheap to meter).

Peppercorn, there was a plan to explore putting the waste in the bottom of subduction zones so they would be carried down into the mantle. I don't know what happened with this idea, but I suspect that concern for the already highly stressed ocean ecology might have had something to do with it.

Steve
 

Offline Geezer

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Can we "export" fission waste ?
« Reply #9 on: 20/12/2010 18:38:01 »
Here's a thought: What would be the longterm effect of dropping it (lightly encased) into the deepest parts of the worlds oceans?

Oi! Start your own thread, matey!  ;D
 

Offline Geezer

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Can we "export" fission waste ?
« Reply #10 on: 20/12/2010 18:50:58 »
Geezer, I am pretty sure there is much more energy made by power plants than would be expended by any number of waste disposal schemes, including launching into the sun, but the energy balance is not important. What is important is the cost. The real cost of current nuclear reactors is already so high that increasing this is unacceptable (and they told us it would be too cheap to meter).

Steve,

It must take quite a bit of energy to send something to the Sun. Perhaps someone has data?

The "cost" of nuclear energy should really factor in the cost of safe disposal of the waste it produces, and burning it in the Sun strikes me as a very good long term solution compared with all the sequestration methods that many people object to.

Nuclear energy is expensive, but I really don't think we have an alternative. BTW, France seems to be doing just fine with its reactors.
 

SteveFish

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Can we "export" fission waste ?
« Reply #11 on: 20/12/2010 19:32:15 »
Geezer:

I just checked up on what Space X, a private launch enterprise in the US, is up to. They are talking about dropping launch costs per pound from $4,000 to $1,300 ($8,800/kg to $2,900/kg) and this is just to low earth orbit. Because spent uranium is heavy and spreading a bunch of radioactive material all over the landscape with the occasional launch failure, out of the thousands that would be required, you might rethink this idea.

Using standard reactor design peak uranium will be here in 20 years. The only way to build many more reactor and have a continuing fuel supply is to build breeders, and these are the ones that create weapons grade material. France has a mess that they probably won't continue, check out the cost overruns of their latest in Finland and on their own soil. There are plenty of less dangerous and less dirty power sources available that will be less expensive in the long run.

Steve
 

Offline Geezer

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Can we "export" fission waste ?
« Reply #12 on: 20/12/2010 19:43:42 »
Steve,

It may indeed be a lousy idea, but I'd still like to understand the energy consumed versus the energy produced. That alone may be sufficient to shoot it down in flames.

I have my own opinions about the need for nuclear energy, but that's probably a debate that we should have in a different thread.
 

Offline peppercorn

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Can we "export" fission waste ?
« Reply #13 on: 20/12/2010 19:45:02 »
Here's a thought: What would be the longterm effect of dropping it (lightly encased) into the deepest parts of the worlds oceans?
Oi! Start your own thread, matey!  ;D
I thought about a pre-emptive apology when I wrote that and I realise now that it was a 'failing' not to include it!  :-X

Peppercorn, there was a plan to explore putting the waste in the bottom of subduction zones so they would be carried down into the mantle. I don't know what happened with this idea, but I suspect that concern for the already highly stressed ocean ecology might have had something to do with it.
Deep enough it should have no effect on ecology I would have thought. (Although answer quietly lest Geezer notices)...
 

SteveFish

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Can we "export" fission waste ?
« Reply #14 on: 21/12/2010 00:06:54 »
Peppercorn:

I suspect that the deep ocean currents could spread a variety of chemicals that might form if a container were breached. I was going to use small type to be quiet, but ....

Steve
 

Offline Geezer

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Can we "export" fission waste ?
« Reply #15 on: 21/12/2010 00:14:35 »
The Shrinkomatic is nigh!
 

Offline peppercorn

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Can we "export" fission waste ?
« Reply #16 on: 21/12/2010 01:53:08 »
Steve,
I like the idea of 'folding' waste back into the Earth's innards - makes me think of making cake mixture :D


The Shrinkomatic is nigh!

Nnnnnnnnnnoooooooooooooooooooo!!
 

Offline CliffordK

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Can we "export" fission waste ?
« Reply #17 on: 21/12/2010 12:01:04 »
The Nuke Plants use about 10% of the power in the Fuel Rods.

It is like filling your tank with gas.
Using 1 gallon.
Dumping the rest
And filling up again.

WE NEED TO START RECYCLING THE FUEL RODS

And, no, making them into toxic bullets doesn't count as recycling.

Once that is started, that should cut the waste stream by 10 fold, and hopefully get rid of some of the most long-lived isotopes.

Burying in the ocean sounds like a very bad idea.  Do we have anything that would hold up to the elements for 100,000 years?  Vitrify it first?

Rather than being dependent on the sedimentary rate, one should just decide how deep of a hole is desired, and bury it.
 

Offline Geezer

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« Reply #18 on: 21/12/2010 16:51:05 »
The Nuke Plants use about 10% of the power in the Fuel Rods.

It is like filling your tank with gas.
Using 1 gallon.
Dumping the rest
And filling up again.

WE NEED TO START RECYCLING THE FUEL RODS

And, no, making them into toxic bullets doesn't count as recycling.

Once that is started, that should cut the waste stream by 10 fold, and hopefully get rid of some of the most long-lived isotopes.

Burying in the ocean sounds like a very bad idea.  Do we have anything that would hold up to the elements for 100,000 years?  Vitrify it first?

Rather than being dependent on the sedimentary rate, one should just decide how deep of a hole is desired, and bury it.

Thanks Clifford. Now, if we could just get back to answering my actual question...... ::)

(Sheesh! - It's worse than herding a flock of cats.)
« Last Edit: 21/12/2010 16:52:37 by Geezer »
 

Offline peppercorn

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« Reply #19 on: 21/12/2010 17:11:10 »
Yes let's get back to the original idea...
It's a terrible one!

Right. New topic!


I think the main problem is it's bloody heavy stuff and there's more than a fading chance of a problem a launch.
 

Offline Geezer

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« Reply #20 on: 21/12/2010 17:16:56 »
Yes let's get back to the original idea...
It's a terrible one!

Right. New topic!


I think the main problem is it's bloody heavy stuff and there's more than a fading chance of a problem a launch.

Look buster - there's only room for one anecdotal physicist around here.

Yes, there could be a launch problem, but you're just using that as an excuse for not doing the math.
 

Offline peppercorn

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« Reply #21 on: 21/12/2010 17:20:38 »
Okay. Fair enough! Now where did I put that slide rule .... *goes off to route in drawers*....
 

Offline Geezer

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« Reply #22 on: 21/12/2010 20:26:39 »
Surely it can't be so difficult to work this out.

How about we determine the amount of work done to elevate a mass far enough above the Earth's surface that it starts to fall towards the Sun, rather than back to Earth? No orbits or fancy trajectories required.
 

Offline syhprum

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« Reply #23 on: 21/12/2010 22:52:20 »
Bodies don't start to fall towards the Sun they retain the orbital energy associated with their orbit around the Sun that has to be removed in some way.
There is no friction in their environment they have to be imparted with an acceleration of 30M/s from some source.
 

Offline Geezer

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« Reply #24 on: 21/12/2010 23:10:20 »
Bodies don't start to fall towards the Sun they retain the orbital energy associated with their orbit around the Sun that has to be removed in some way.
There is no friction in their environment they have to be imparted with an acceleration of 30M/s from some source.

Ah! Good point. So we'd have to include the work required to achieve that deceleration of the mass, or it would just stay remain in orbit around the Sun.
 

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Can we "export" fission waste ?
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