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PostPosted: Oct 27, 2008 2:12 pm 
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T. S. Jones1, S. Ramachandran1, W. B. Yerrick1 and J. W. Gahan2

(1) Allegheny Ludlum Industries, Inc., Brackenridge, Pa.
(2) General Electric Co., Schenectady, N. Y.

Received: 15 June 1970

Abstract An electromagnetic pump for liquid steel was built and subjected to laboratory testing. This pump was a flat linear induction pump whose flow channel was approximately 5/8 by 12 in. in cross section by 51 in. long. This pump was successfully operated with molten stainless steel in a demonstration in which a pressure development of about 9 psi was achieved. Possible areas of application of electromagnetic pumping to steelmaking operations and directions of further development are considered.

Also see:

http://www.journalarchive.jst.go.jp/jnl ... nlabstract


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PostPosted: Oct 27, 2008 2:31 pm 
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Do these molten salts conduct electricity?


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PostPosted: Oct 27, 2008 2:48 pm 
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USPWR_RO wrote:
Do these molten salts conduct electricity?


See

http://www.electrochem.org/meetings/sch ... 4/3003.pdf

David L said ..."and finally NaF-KF-(U,Th)F4 which is one of my secret recipes that has a surprisingly low melting point (K is bad for thermal spectrums but quite good for anything fairly hard). David L. "

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PostPosted: Oct 27, 2008 6:17 pm 
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Some SFR designs assume the use of E-M sodium pumps.

This would be real sweet for MSRs, if possible.


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PostPosted: Oct 28, 2008 2:24 am 
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Few problems to that:

- There is also a document on the document repository that talks about destabilizing the salt when high magnetic fields are used.
- E.M. pump have a low inertia. Pumps in a MSR need to have a high inertia such that in the event of a loss of power reactivity by decreasing flow is inserted sufficiently slow. (There are things to fix this, but as MSR operate rather well using normal pumps why do so...)

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PostPosted: Oct 28, 2008 12:02 pm 
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The things I noticed the ORNL folks struggled t with were
#1 The chemical separation process was only talked about so far as I could tell. They never got to a prototype stage.

#2 He gas system - clogging up with metal deposits and bubbles causing power fluctuations. My impression is that the power fluctuations were not a major concern once they were understood and expected. The clogging seemed to be something solvable but requiring engineering.

#3 Vacumn distilling. Trouble with temperature sensors and clogging.

#4 Fluorinating not only the U and Np but also the Pu. Seems like they got it mostly working but would need another prototype to test out ideas for protecting the vessel walls from the fluorine gas with solid salt.

I don't recall that they had any trouble with the pumps. So it makes me wonder why the big concern over the pumps?


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PostPosted: Oct 28, 2008 12:59 pm 
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Lars wrote:
The things I noticed the ORNL folks struggled t with were
#1 The chemical separation process was only talked about so far as I could tell. They never got to a prototype stage.

#2 He gas system - clogging up with metal deposits and bubbles causing power fluctuations. My impression is that the power fluctuations were not a major concern once they were understood and expected. The clogging seemed to be something solvable but requiring engineering.

#3 Vacumn distilling. Trouble with temperature sensors and clogging.

#4 Fluorinating not only the U and Np but also the Pu. Seems like they got it mostly working but would need another prototype to test out ideas for protecting the vessel walls from the fluorine gas with solid salt.

I don't recall that they had any trouble with the pumps. So it makes me wonder why the big concern over the pumps?


I foresee a LFTR with a salt temperature of 1200C. That high temperature will be hard on the mechanical pumps. Two key design goals in LFTR development are to maximize the Mean Time Between Failure (MTBF) of both the pumps and the heat exchangers. Can you get better MTBF using magnetic fields or from mechanical pump bearings heated to at least 1200C? Testing is required to provide that answer but magnetic fields probably hold and advantage here.

In addition, any level of redundancy can be provided by the use of a series of magnetic pumps string out in a straight line over a length of a single pipe as opposed to a multi pipe manifold required by a redundent mechanical pump system that must be build without the use of welding. If at all possible, the fabrication of such a manifold will be expensive and should be avoided to minimize LFTR manufacturing costs.

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PostPosted: Oct 28, 2008 4:30 pm 
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I'm more inclined to settle for getting a lower temp LFTR running at all. We get most of the benefits and require less materials R&D. LFTR has a hard enough time with being relegated too far in the future to invest in now so I'm more inclined to make less dramatic changes.


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PostPosted: Oct 28, 2008 4:42 pm 
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OTOH, high temperatures allow you to get the absolute minimum in reactor size, by using straight UF4 or UF4/ThF4 or UF4/PuF3 or UF4/ThF4/PuF3.

Combined with a few other tricks, you could get a plant that is basically lab-scale, producting the same power as a big huge graphite-moderated MSR.

Much less development risk in such small units, in spite of the challenging thermal conditions....


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PostPosted: Oct 29, 2008 7:48 am 
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jaro wrote:
OTOH, high temperatures allow you to get the absolute minimum in reactor size, by using straight UF4 or UF4/ThF4 or UF4/PuF3 or UF4/ThF4/PuF3.


Sounds interesting! Then you can run on fast spectrum and use tungsten :-)
What are the melting/boiling temperatures of these mixtures?


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PostPosted: Oct 29, 2008 8:05 am 
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Phase diagram.....


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PostPosted: Oct 29, 2008 8:24 am 
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Thank you. What about boiling points?

Could one use this idea for a TRU (instead of U233) fuel salt?

Perhaps a flail-safe design would have core temperature stabilized by blanket boiling - this would also work an excellent heat transfer (heat pipes close to the core as apart of the blanket, just a bunch of holes along the vertical core) up to a HX, requiring a different salt composition for the blanket.

If such salt is not possible, one could interlace the core and the blanket by heat pipes separated from the blanket, and use a Na or Na/K boiling metal for cooling medium in the heat pipes.


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PostPosted: Oct 29, 2008 8:58 am 
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TRU will be a small percentage so likely it won't change the properties much.
Using 20% leu will allow us to start more plants simultaneously - starting hundreds of fast spectrum plants actually requires a significant amount of Pu.
Roughly 1000 plants with 50% u235 and 50% Pu as starter fissile will clean up all the LWR wastes that exist.
From there they run on u233 that they generate and generate surplus so that we can start u233 unity breeders for the rest of the world.
THis would produce a very fast spectrum (nothing to moderate at all) so the resonance of the fertile in the salt is needed for control.
Hence we have (as David would put it) a 1 1/2 fluid design.


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PostPosted: Oct 29, 2008 9:45 am 
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Lars wrote:
TRU will be a small percentage so likely it won't change the properties much.


Actually I'd like to run the cores on pure TRU - solving the "waste issue" is a big plus. U233 would be bred in the 2nd fluid.


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PostPosted: Oct 29, 2008 11:11 am 
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ondrejch wrote:
I'd like to run the cores on pure TRU - solving the "waste issue" is a big plus.

You could actually just take the heavy metals (U + TRU) from LWR spent fuel, convert them to fluorides and stick them in an MSR, without any further processing or separation or enrichment:
The SNF has ~0.9% U235 plus ~0.7% TRU (nearly all Pu), which would be plenty for a "thermal" MSR.
That's a big diference compared to a fast MSR, which would require additional fuel processing, in order to boost the fissile fraction to ~15%.

Plus, you could still get some of the benefit of the fast reactor (no carrier salt) by having large-diameter fuel channels (a bit larger than the mean free path of fast neutrons in dense media -- a few inches).


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