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 Post subject: Re: End Game
PostPosted: May 25, 2009 4:29 am 
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Here is what I'd fix:
[*]Diagrams. You need to show the plant flow diagram. What goes in, what is extracted every 10 years, what flows to waste and what is returned.
[*]Treating the U-233 as an afterthought doesn't work. Talk about U-233 in the section where you introduce the species to be minimized: not just the TRUs, but U-233 and maybe a couple of the 1000-year fission products too.

I also wonder about losses to the environment that do not go through a controlled waste stream. If I understand right, Areva's reprocessing facility loses a few tenth's of a percent of the material that flows through it, and I think the British facility has lost a bit more. Although in the British case those losses are considered exceptional, for a large deployment accidental releases will not be exceptional. Once you've reduced the deliberate losses to waste to very small amounts, I suspect accidental losses will dominate.


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 Post subject: Re: End Game
PostPosted: May 25, 2009 9:44 am 
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Thanks,

The primary point of the paper was to show that the end game inventory was not the dominate source as the French previously believed. The status is that I provided the French with the information some months ago. It is time to ask them if they have tried to verify my results.

There is a reason I did not add the u233 inventory discussion up front. When we startup the reactors you see a significant (75%) drop in TRU inventory. This is because it is replaced with u233. Also I started up 1k with TRU and 8k GW with u233. If I show the up front inventory including u233 it will jump up 9x. Not the message I wanted to give. Perhaps I should not show inventory at all. But since there is concern over Pu both from a waste and proliferation concern I thought it would be a selling point to show that we rapidly and significant reduce the amount of Pu in the world.


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 Post subject: Re: End Game
PostPosted: Nov 29, 2009 1:57 pm 
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Cool!

If the reason for shutting down the fission plants is that fusion plants are cheaper (you never know, 200 years is a long time!) then that may also help destroy the wastes (external source of neutrons). Unless it is aneutronic fusion.

Some people also mentioned using hard gamma rays as a possible future transmutation strategy. With a timeline of centuries, many things look possible.

If 'the space age' really takes off, then final reprocessing may also be done on the moon. Contamination of the facility isn't a problem there. The nasties will stay on the moon, the good stuff gets sent back to earth.


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 Post subject: Re: End Game
PostPosted: Nov 30, 2009 12:04 am 
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If you just shoot vitrified fission products moonwards. it may be cheaper. you could do it as soon as you can handle it. Not wait till you can work on the moon! 8)


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 Post subject: Re: End Game
PostPosted: Nov 30, 2009 12:21 am 
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It is a tough sell to ship rad wastes into space. The energy it takes to get stuff into space it a lot. The accident rate on launches is extremely high compared to nuclear power plants. Geological storage for the stuff we don't use is a reasonable choice. For now, I'd use above ground storage since the "wastes" contain lots of exotic materials that future generations may want.


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 Post subject: Re: End Game
PostPosted: Nov 30, 2009 12:48 am 
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Lars wrote:
fnord wrote:

I don't particularly agree with his 200 year lifetime assumption for his NM-TMSR, and would dearly love to see how he developed some of his numbers.



The design target for a plant lifetime is 60 years. The nice thing about MSRs is that we can transfer the salt from a plant being decommissioned to a new one with almost no transuranic waste. When analysing the TRU waste flow then the lifetime of an individual plant becomes irrelevant. What is important is how long society depends on these type of plants for its energy. I picked 200 years rather arbitrarily.


A quick note that graphite and some components from LFTRs will be sufficiently contaminated with transuranics that they will require geologic disposal. This is certainly not the end of the world, as it is known that this can be done successfully (the U.S. is currently operating a salt repository to dispose defense transuranic-contaminated wastes). Despite optimistic statements to the contrary, all fission energy systems require the capacity to dispose some materials into geologic repositories or their equivalent.

On the end game question, if one wanted to dispose of LFTR uranium and thorium without concern for future recovery for weapons use, one can simply dilute it with depleted uranium (there will be plenty around) prior to disposal, making the U-233 unusable. No equivalent dilutant exists for plutonium, so the IAEA has concluded that repositories with spent fuel from the uranium cycle will require permanent safeguards monitoring.


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 Post subject: Re: End Game
PostPosted: Nov 30, 2009 2:14 am 
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Wouldn't they prefer we put the plutonium in a LFTR and burn it up?

Graphite isn't mandatory for LFTR, the French approach has no core graphite and can achieve neutron spectrums from somewhat faster than LWR to somewhat slower than oxide based solid fuel breeders.

If the plutonium concentration is low enough that we can't reasonably recover it (say 100grams/400kg of lanthanide radioactive wastes) then would it really need to be guarded? Although this isn't the end of the world it does seem rather unnecessary. Extracting such low concentration of plutonium that is mostly Pu238 would seem to be much much harder than enriching uranium.


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 Post subject: Re: End Game
PostPosted: Nov 30, 2009 2:38 am 
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Lars wrote:
Wouldn't they prefer we put the plutonium in a LFTR and burn it up?


What, you mean they should suggest that something should be done to deal with the problem? You have forgotten that the IAEA as an institution is the purest of pure bureaucracy: it exists to exist. Actually solving a problem puts that core mission at risk. </sarcasm>


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 Post subject: Re: End Game
PostPosted: Nov 30, 2009 4:09 am 
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Lars wrote:
It is a tough sell to ship rad wastes into space. The energy it takes to get stuff into space it a lot. The accident rate on launches is extremely high compared to nuclear power plants. Geological storage for the stuff we don't use is a reasonable choice. For now, I'd use above ground storage since the "wastes" contain lots of exotic materials that future generations may want.


No hurry, this is a long term objective; your scenario lasts 200 years! If or when space travel becomes more reliable and cheaper, it may become an option. And while we wait, the radwaste in the intermediate storage will be less and less dangerous due to decay, and may even as you say yield some valuable elements if this can be extracted effectively and efficiently. Combine that with discounting, and more time to do research on geologic disposal, transmutation etc. it makes a lot of sense to postpone geologic disposal for at least a few decades. In a rather strange twist, it appears that postponing geologic disposal may actually cause our children to be better off!

If lunar reprocessing won't make it, we can still do the geologic repository on earth. However, one might think that the moon would be the ultimate geologic repository!

As for the energy required for space travel, it would be trivial compared to the output of TWs of reactors over several decades...

As for safety, the radwaste would have to be highly armored against both accidents as well as re-entry if the good stuff is sent back.

Alternatively, one may not do reprocessing at all and use the moon as geologic repository. As Per points out, this will be required for some contaminated equipment anyway.


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 Post subject: Re: End Game
PostPosted: Nov 30, 2009 3:53 pm 
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Cyril R wrote:
Lars wrote:
It is a tough sell to ship rad wastes into space. The energy it takes to get stuff into space it a lot. The accident rate on launches is extremely high compared to nuclear power plants. Geological storage for the stuff we don't use is a reasonable choice. For now, I'd use above ground storage since the "wastes" contain lots of exotic materials that future generations may want.


No hurry, this is a long term objective; your scenario lasts 200 years! If or when space travel becomes more reliable and cheaper, it may become an option. And while we wait, the radwaste in the intermediate storage will be less and less dangerous due to decay, and may even as you say yield some valuable elements if this can be extracted effectively and efficiently. Combine that with discounting, and more time to do research on geologic disposal, transmutation etc. it makes a lot of sense to postpone geologic disposal for at least a few decades. In a rather strange twist, it appears that postponing geologic disposal may actually cause our children to be better off!

I honestly think any sort of space based nuclear fuel processing is a bit ludicrous, but centuries down the line, who can tell. And really we can do dry storage casks for centuries. My opinion is by then we'll tear them apart for fission products and transuranics on earth, but the bottom line is it isn't a problem we need to worry about today.


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 Post subject: Re: End Game
PostPosted: Nov 30, 2009 4:07 pm 
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Per Peterson wrote:
A quick note that graphite and some components from LFTRs will be sufficiently contaminated with transuranics that they will require geologic disposal.


Graphite could be combusted with oxygen, and the CO2 released to the atmosphere, while transuranics could be retained, could they not? This would reduce the mass needing burial tremendously.

http://www-pub.iaea.org/MTCD/publicatio ... son%29.pdf

TCM-Manchester99: Nuclear Graphite Waste Management


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 Post subject: Re: End Game
PostPosted: Nov 30, 2009 4:42 pm 
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Kirk Sorensen wrote:
Per Peterson wrote:
A quick note that graphite and some components from LFTRs will be sufficiently contaminated with transuranics that they will require geologic disposal.


Graphite could be combusted with oxygen, and the CO2 released to the atmosphere, while transuranics could be retained, could they not? This would reduce the mass needing burial tremendously.

http://www-pub.iaea.org/MTCD/publicatio ... son%29.pdf

TCM-Manchester99: Nuclear Graphite Waste Management


Wouldn't that release all the carbon-14 into the air? Wouldn't that be a problem?


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 Post subject: Re: End Game
PostPosted: Nov 30, 2009 5:25 pm 
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Cyril R wrote:
Wouldn't that release all the carbon-14 into the air? Wouldn't that be a problem?


That's exactly what I'm wondering--how much C-14 is in the graphite and would it be a big deal if it was dispersed?

Remember, C-14 is made from nitrogen-14, not primarily from carbon. You have to get a neutron capture in C-13, which has a small fraction in natural carbon and has a small neutron absorption cross section.

Big C-14 releases will certainly mess with the heads of future paleontologists who will think our civilization existed much further back in the past.


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 Post subject: Re: End Game
PostPosted: Dec 01, 2009 3:44 pm 
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Kirk Sorensen wrote:
Cyril R wrote:
Wouldn't that release all the carbon-14 into the air? Wouldn't that be a problem?


That's exactly what I'm wondering--how much C-14 is in the graphite and would it be a big deal if it was dispersed?

Remember, C-14 is made from nitrogen-14, not primarily from carbon. You have to get a neutron capture in C-13, which has a small fraction in natural carbon and has a small neutron absorption cross section.

Big C-14 releases will certainly mess with the heads of future paleontologists who will think our civilization existed much further back in the past.


DOE is working to develop processes other than oxidation to remove the graphite from TRISO fuel so that it can be reprocessed, because the C-14 is an issue. They are also working on processes to recycle this graphite into new graphite components for VHTRs.

However, I'm perfectly comfortable with the idea of permanently disposing of graphite in repositories once it's used, rather than spending extra to attempt to recycle it. Carbon is certainly not a scarce resource. Our problems today are not with putting carbon into the ground, they are with the amounts of carbon (coal) we're removing from the ground.


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 Post subject: Re: End Game
PostPosted: Mar 16, 2010 7:02 pm 
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Alex Goodwin wrote:
I'm more of the opinion that Jevon and his paradox will bite back with a vengeance, wiping out any gains from improved energy efficiency.


Indeed. Two years late, but his name was actually Jevons. -Carl


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