Energy From Thorium Discussion Forum

Here's an interesting presentation by Miroslav Hron containing lots of interesting details about the Sphinx Project, which is a project to develop technology designed to eliminate actinides using molten fluoride technology:

http://www.nr.titech.ac.jp/coe21/eng/events/Ines-2/pdf/3B2/69_Hron.pdf

I don't know about others, but this sounds to me like the Czechs are driving towards an eventual full-blown MSR plant project.

The presentation mentions the justification of dealing with spent fuel from the six reactors (combined) at Dukovany and Temelin -- and there has been talk about expanding the VVER fleet further, either at Temelin or at a new "green field" site (possibly a former coal plant site).

While I am somewhat dubious that they could swing this on their own, the chances of success would likely improve with cooperation with France and India.

Jaro,

I completely agree. Remember the news from the CNS?
It seems to me that the group at the UJV is actively seeking partners to do just what you suggest. I sure hope Dr. Forsberg can make something happen so that the working group can evolve into a real MSR development project.

Isn't Forsberg the guy who wants to turn MSRs into solid fuel reactors, using TRISO type oxide fuel ?

....that wouldn't be much help for efficient processing & burning of transuranics.

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Wow--this is super interesting! Thanks Honzik!

These guys appear to be actually building some kind of hybrid liquid-fluoride/solid-core reactor...I'm still fuzzy on a lot of what they're trying to do but they certainly get a lot of credit for doing something!

Me too -- although I think I saw somewhere in that presentation that its supposed to be a zero-power critical assembly.
If that's the case, then the VVER fuel rods are there just to take the assembly to critical, while minimizing the amount of molten salt -- since its just an experiment to observe various technical aspects, rather than a practical commercial design.....

Their fuel cycle concept is very interesting and very similar to what I've been thinking about lately:



Namely, take spent uranium oxide fuel and fluorinate it. This step isn't very radical since we take uranium oxide out of the ground and fluorinate it (first to UF4 and then to UF6) to get it ready for enrichment. The nice thing about fluorination is that it is chemically favored (uranium fluoride being more stable than uranium oxide) and that once you've got it fluorinated, removing the uranium from the minor actinides (MA) and fission products is pretty easy. Just fluorinate it some more, changing the uranium from UF4 to UF6 and it will come out as a gas.

You can also remove fission products like technetium and molybdenum through fluorination since they will form volatile hexafluorides like uranium (TcF6, MoF6, and UF6, respectively). Each of those volatile hexafluorides condense at a different temperature, allowing you to rather easily separate them. Indeed, each of these steps is ALREADY done as uranium is purified in preparation for enrichment, something that's going on on a huge scale right now.

Removing plutonium and other minor actinides from the fluoride mixture used to be a problem that I thought could be a showstopper, but I read this paper by some French researchers who showed how you could remove minor actinides through reductive extraction with metallic aluminum. Basically, in a simple form, it works like this. Metallic aluminum would rather be aluminum fluoride more than minor actinide fluorides would rather NOT be metal, so the aluminum steals the fluorine ions away from the MA fluorides and they come out of solution as metals. But the fission products are left behind.

So now you have one solution of fission product fluorides, suitable for disposal and another bunch of metallic minor actinides, which could then be chlorinated with chlorine-37 and used as the feed to a fast-spectrum chloride reactor, where they could be fissioned and destroyed.

That would be my only real difference with this fuel scheme--I think that a fast-spectrum chloride reactor will do a much better job destroying minor actinides than a thermal (or epithermal) fluoride reactor. Maybe I'm wrong, but everything I've seen points to that conclusion.

I suspect that the lab's set-up is limited to a thermal (or epithermal) fluoride reactor, simply because they haven't got access to any fuel that's enriched high-enough to make a fast-spectrum chloride reactor go critical.
Note the use of the VVER hexagonal fuel rods, as driver fuel.

Honziku -- isn't there a text report somewhere that goes with this slide presentation ? (Thnx)

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Here are a few references I've found. Here's an abstract from the ICAPP07 Conference (with contact information):
http://www.inspi.ufl.edu/icapp07/program/abstracts/7424.html

Here's a paper on the subject, although it's hard to put a date on it:
http://tauon.nuc.berkeley.edu/references/2005_10_Global_Tsukuba/GL0xx/GL094DF.pdf

I was thinking: Since we have Miroslav Hron's contact address, couldn't we write and ask for some of his and/or his colleague's latest papers on MSRs, and post them in EFT's reference section? My guess is most of the papers are in English.

Even better, could we get him to join the discussion forum?

(But I'll definitely make any papers available that aren't already available on the net...)

Hmmm -- from this document, I get the impression that they're actually serious about a concept for running VVERs (ie. PWRs) with a few fluid fuel loops in the middle !
Talk about complicating your life, unnecessarily !
...how the heck do you unplug the fluid fuel loops when you want to take the RPV head off for the periodic refueling of the normal fuel rods ??
Bizarre.

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On second thought, maybe there are no fluid fuel "loops" in their concept -- just closed hexagonal containers, with heat transfer through the container walls, to the light water coolant, that cools the rest of the core as well ?
Does that make any sense ?
Why sacrifice the possibility of a high-efficiency Brayton cycle, in an ordinary PWR with a 35% efficient Rankine ?
Are we really so desparate, that ANY sort of technological departure from standard PWRs must be avoided like the plague ??
Boy, things must be worse than I thought !

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Maybe all that they care about is the transmutation of minor actinides in the salt. Pretty lame, I agree, but in such a case the salt simply serves the purpose of a convenient solvent for the minor actinides, and any heat production in the salt from fission is removed via conduction to the light water coolant.

On the other hand, the GNEP people might view this as a convenient way of avoiding having to build a whole lot of "Advanced Burner Reactors" (ie. fast reactors) to get rid of TRUs.

Traditionally, HWRs (like CANDU) are considered as particularly well suited for this role, requiring far fewer ABRs.

So this MSR-PWR fusion may also be viewed as a shot across the bow of the CANDU industry....

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Wouldn't you be making more TRUs in the VVER fuel than you could possibly hope to burn up in a fluoride salt channel?