Energy From Thorium Discussion Forum

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PostPosted: Dec 06, 2010 3:43 pm 
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Joined: May 24, 2009 4:42 am
Posts: 823
Location: Calgary, Alberta
For a basic NaCl/UCl3/PuCl3 chloride salt fast reactor system with or without a UCl3 blanket, can people please outline the options for fuel salt cleanup of fission products and selective transfer of blanket fissile to the core.

The ideal functional requirements would create three or perhaps four process streams, uranium in one, Pu and TRU's in the second and the last step to be able to separate FP's and radiosulphur from fuel salt.

Simple systems would be preferred, if they are practical and reasonably effective.


PostPosted: Dec 06, 2010 4:00 pm 

Joined: Jul 14, 2008 3:12 pm
Posts: 5045
Chlorination might be hard since there is considerable volitility overlap of the UClx series. But a vacuum distillation unit would work ok, maybe not as efficient as fluorides still, but thats fine for a fast reactor. You can afford a bunch of fission products. In fact, beyond noble stuff removal that comes out easily without touching the fissile, why process at all? The French think the fast TMSR fluoride reactor can go for 20 years without salt seeker processing (of course if thats true then we don't need a chloride reactor so much anymore...) If you must process going for the vacuum still seems like a reasonable development. Lower temperature than the fluoride still. Thorium can also be used and will distill out at reasonable temperatures so you don't have to go fancy with reductive extraction and all that.

I wouldn't count on a barrier in a fast reactor with high power density with temperatures in excess of 900 K. The barrier may end up as cork in about, oh, three months - if you're lucky. Better go for single fluid and make it big, then line the outside with non-moderating non-structural reflectors and ditto neutron poisons. Perhaps a 1 1/2 fluid will be good enough, I don't know.

PostPosted: Dec 06, 2010 5:01 pm 

Joined: Jul 28, 2008 10:44 pm
Posts: 3063
In a 1 1/2 fluid design the second wall (outside the blanket) can have the same (or better) protection as your wall in a 1 fluid design. That is, we can put neutron absorbers in front of the wall to protect it. With a blanket we can productively use most of the neutrons and then settle for simply absorbing the ones that make it to the second wall.

I wonder if the first wall (core/blanket) need be structural. What if the blanket were designed to have fission products in it - that is, it was the same salt as the fuel salt but without uranium (or almost without uranium)? Second, what if the design had a means to passively ensure the fluid pressure on both sides of the wall was the same. Any pinhole leaks would be inconsequential to normal operations. If the wall should collapse it would dilute the core salt so that we would lose criticality - so there is no safety issue with the collapse as far as mixing the blanket and fuel salts. The only concern I can think of would be if the wall shed pieces into the fuel salt and those munged up the pump or the HX. Seems like a possible operational issue but the wall could tolerate a lot more damage if the criterion was that it should not shed pieces rather than a criterion of having a certain strength.

PostPosted: Dec 12, 2010 4:05 am 

Joined: Apr 19, 2008 1:06 am
Posts: 2240
Boiling points of thorium and uranium chlorides are below 1000C and they can be distilled from fission products. Processing has to be based on chloride volatility. Some fission products and Chlorides(ZrCl4) can be removed under operation.

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