What about the higher halogens?

Threads relating to the design of liquid-chloride, fast-spectrum reactors as well as fuel reprocessing.
Cyril R
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Re: What about the higher halogens?

Post by Cyril R » Aug 02, 2010 1:29 pm

Well you could try to run super hot pure uranium metal in liquid state. But its insane from a corrosion and materials perspective.

NNadir
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Re: What about the higher halogens?

Post by NNadir » Aug 02, 2010 10:11 pm

Cyril R wrote:Well you could try to run super hot pure uranium metal in liquid state. But its insane from a corrosion and materials perspective.
I've played around in my mind with iron/plutonium eutectics in this sort of game.

Of course the IFR people had an awful time with Fe/Pu eutectics, and ended up with a zirconium alloy as I recall, not that I know. But they were trying to be solid phase kind of guys and gals.

There is nothing quite as exciting as phases of plutonium and its alloys, and quite a bit is known of them.

It would be interesting to know if any of the fissionable actinides have peritectics equivalent to the iron/carbon peritectic known as austentite. Of course a peritectic of an actinide in a neutron flux would be an interesting thing, to be sure.

Such a peritectic would be a swell find. It is now more possible to construct modeling systems for this sort of thing than ever before.

I am rather surprised at the number of calculated phase diagrams one can find in the literature these days.

Cyril R
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Re: What about the higher halogens?

Post by Cyril R » Aug 03, 2010 12:24 pm

Hmm, iron. That would make EM pumps interesting. If your liquid plutonium eutectic system develops a leak, things will certainly get even more 'interesting'. However the high HM density of liquid fissiles is rather tempting. Plutonium has a reasonably low melting point so you can have a lot of plutonium in the eutectic while staying at a reasonable melting point. Hell, you could just go for straight TRU to simplify processing. Take all of the TRU from LWR SNF. This seems ideal for a fast spectrum reactor (breed ourselves a lot of U-233 for example). The thorium part (in case of two fluid) gets tricky, its melting point is high and thorium is also not very soluble in bismuth. You could try magnesium, or use a solid blanket.

An important question is where do you put this stuff in. Surely not carbon, you'll get carbides? Metals probably. Maybe alloys of beryllium, zirconium, niobium etc.

jagdish
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Re: What about the higher halogens?

Post by jagdish » Aug 04, 2010 3:42 am

You could have a lead-plutonium (or all the TRU's combined) eutectic as both are low melting metals and plutonium is in any case more soluble than uranium or thorium. The fertile thorium or uranium you want in the core can be put there as rolls of wire mesh with a vertical axis, generally acting as solid fuel internal blanket
but widely distributed. Some could be in a blanket too. With the fluid fuel, dissolution of some fertile or created fissile fuel would not amount to a problem
When you have enough U233 for use as fissile fuel, just dissolve it as a uranyl salt for an even better fluid fuel in a 'Water Boiler'. Then you can go back to thermal spectrum. Thorium wire mesh can continue.

Owen T
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Re: What about the higher halogens?

Post by Owen T » Aug 04, 2010 10:23 am

jagdish wrote:You could have a lead-plutonium (or all the TRU's combined) eutectic as both are low melting metals and plutonium is in any case more soluble than uranium or thorium. The fertile thorium or uranium you want in the core can be put there as rolls of wire mesh with a vertical axis, generally acting as solid fuel internal blanket
but widely distributed.
If the uranium mesh is fine enough any bred plutonium may be leached out of it by the molten lead. Could this effect be made reliable enough to rely on it as a form of slow "reprocessing" right inside the core? It the uranium blanket is in the form of fine powder and stored inside bricks of some porous ceramic into which the lead can infiltrate then diffusion might do the rest of the work.

Cyril R
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Re: What about the higher halogens?

Post by Cyril R » Aug 04, 2010 1:08 pm

That might work:

http://resources.metapress.com/pdf-prev ... ze=largest

Although it does not look like Pu-Pb forms low melting point eutectics:

http://resources.metapress.com/pdf-prev ... ze=largest

Iron is perhaps more interesting. You only need 9.5% iron to get to the Pu-Fe binary eutectic point, which is around 430 degrees C. That's a lot of plutonium!

http://www.freepatentsonline.com/3600585.pdf

Molten plutonium is kinda scary though. I also heard that plutonium only fuel is real tricky in terms of control.

jagdish
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Re: What about the higher halogens?

Post by jagdish » Aug 05, 2010 1:07 am

Pure liquid plutonium is scary. It has to be diluted by lead in which it is more soluble than Th or U. The increased volume will also accomodate fertile neutron absorber Th or U. Plutonium leaching out to lead solution wholly or partly should be acceptable so far as it is fairly widely distributed in the core. U233 may leach out less than the Pu. I prefer Pb based fluid fuel as Fluorine is light and may take the core to resonance region. Cl may require separation of isotope Cl37, increasing the costs. Other halogens are rare and may cost much more. Graphite moderator has its own problems and results in radioactive waste.
Fissile in fluid and fertile as solid phase can form a convenient matrix and leaching of some fissile created to liquid is not necessary but will cause no harm if it takes place to some extent. In case of Th-U233 cycle, the fissile could be in water or heavy water solution. Cheaper light water is to be preferred if additional fissile feed is not required as is expected in case of LFTR.
The two phases can be separately electrolysed for removal of results of muclear reactions. Fertile feed can be added at that stage.

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