[Geezer (OP)]

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?

[William Myres]

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]

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.

[Geezer (OP)]

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.
 

[syhprum]

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.

[Geezer (OP)]

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?

[peppercorn]

Here's a thought: What would be the longterm effect of dropping it (lightly encased) into the deepest parts of the worlds oceans?

[Mazurka]

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]

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

[Geezer (OP)]

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!  []

[Geezer (OP)]

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]

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

[Geezer (OP)]

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.

[peppercorn]

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!  []

I thought about a pre-emptive apology when I wrote that and I realise now that it was a 'failing' not to include it!  []

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]

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

[Geezer (OP)]

The Shrinkomatic is nigh!

[peppercorn]

Steve,
I like the idea of 'folding' waste back into the Earth's innards - makes me think of making cake mixture []

The Shrinkomatic is nigh!

Nnnnnnnnnnoooooooooooooooooooo!!

[CliffordK]

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.

[Geezer (OP)]

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.)

[peppercorn]

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.