Energy From Thorium Discussion Forum

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PostPosted: Dec 30, 2010 3:53 am 
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Well couldn't you just put neutron poisons everywhere to prevent criticality? Baths filled with boron balls, boron piping etc.

Chemistry isn't perfect. If you do one thing you always end up with another. Often that is something you don't want. The attraction for dry processing is very little chemistry is involved. In the case of vacuum distillation no chemical change is involved at all. Crystallization and sublimation techniques are equally promising.

BUT for the LFTR you need fluorides anyway so it makes sense to convert it all in one step. Why use a water based chemistry with organic solvents when you really don't want any of those materials present in your LFTR?

Based on what Luke said, a hydrofluorinator reaction should be: 4HF+UO2=2H2O+UF4. I wonder if the melt could be quickly sent to a vacuum still to grab most of the PuF4 and perhaps even some AmF4 and CmF4? Or is the dissociation to trifluorides very rapid for the transuraniums?


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PostPosted: Dec 30, 2010 11:38 am 
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Cyril,
Do you have any data for the vapor pressure of PuF4, AmF4, or CmF4?
I wonder if we couldn't promote PuF3 to be PuF4 by bubbling F2 through the liquid after we have removed the UF4 then do a second round of vacuum distilling.


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PostPosted: Dec 30, 2010 12:23 pm 
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Lars wrote:
Cyril,
Do you have any data for the vapor pressure of PuF4, AmF4, or CmF4?
I wonder if we couldn't promote PuF3 to be PuF4 by bubbling F2 through the liquid after we have removed the UF4 then do a second round of vacuum distilling.


Sorry, no vapor pressure formulae from me! Its just that the melting and boiling points aren't that radically different from UF4. If the metal phases thermodynamics are any indication, Pu, Np, and Am will come out of the vacuum still, Th definately stays put, Cm might be harder (this does make reduction to metal and zone refining/distillation of the metal attractive). Some documents mention that dissociation of PuF4 is faster under vacuum so that's not good. But I'm no chemist and am struggling with even the basics, so I should shut up before one of the chemists calls me out again :oops:


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PostPosted: Dec 30, 2010 12:59 pm 
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A quick check turned up this paper on trying to measure PuF4 vapor pressure. They got some data, but their sample decomposed to PuF3 during the experiment. It doesn't look very promising as a vac still candidate - and why bother? Electrochemical reduction will get residual U +all TRUs, but NOT Th, deposited leaving the salt seekers behind, if that's what you want, but for Kirk's demo, it's not relevant.


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PostPosted: Jan 02, 2011 8:05 am 
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Ok, here's a nice hydrofluorination experiment that suggests kirk can use a solid-gas HF + H2 + AnO2 reaction to make UF4, PuF3, AmF3 and CmF3. The hydrogen put the minor actinides in trifluoride form, a more convenient reducing agent than magnesium (since you have to use a gas anyway).

Apparently the hydrofluorination in molten FLiBe is ineffective due to limited HF solubility. That's too bad, since it means handling everything as powder. It's going to be a, uhm, grind. :lol: but at least you won't have to buy any FLiBe, Kirk!

The experiment used cerium as a minor actinide simulant. They suggest copper-nickel alloys (Monel) for the equipment.

http://www.cheric.org/PDF/JIEC/IE08/IE08-1-0098.pdf

Seems like you can just do this and then vacuum distill the UF4 out. Upside is no difficult handling of corrosive F2 and PuF6. Downside is that you'll also need to develop a vacuum still, but this is needed anyway. What kind of resources do you need to develop a vacuum still, Kirk?


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PostPosted: Jul 10, 2018 1:19 pm 
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The Department of Energy's Office of Nuclear Energy answers the call! It looks like we're going to be able to do this work at long last!

U.S. Department of Energy Provides Nearly $20 Million for Domestic Advanced Nuclear Technology Projects

Quote:
Fluorination of Lithium Fluoride-Beryllium Fluoride (FLiBe) Molten Salt Processing – Flibe Energy (Huntsville, AL) has teamed with Pacific Northwest National Laboratory (Richland, WA) to examine the use of nitrogen trifluoride as an agent to remove uranium from a molten-salt fuel mixture as a preliminary step for the removal of fission products.


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PostPosted: Jul 10, 2018 7:20 pm 
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Congratulations! Another important step forward for LFTR's and related MSR's.


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PostPosted: Jul 14, 2018 5:06 pm 
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I've thrown up a few blog posts in the last few days on some background and technical information about fluorination, some of which I put together for our successful DOE proposal:

Fluorination Technical Background Info

Fluorination Work under the MSRP


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PostPosted: Jul 23, 2018 7:46 pm 
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This historic PNNL lab runs 'hot' and 'quiet'

Quote:
This juxtaposition of old and new is found in the Radiochemical Processing Laboratory, a 65-year-old facility that is essential to nuclear science and engineering research at the Department of Energy’s Pacific Northwest National Laboratory.


Attachment:
RPL facility.jpg
RPL facility.jpg [ 28.31 KiB | Viewed 1634 times ]


This is where we'll be doing our fluorination work.


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PostPosted: Jul 23, 2018 9:47 pm 
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That is awesome, congratulations!


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