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PostPosted: Oct 23, 2013 10:06 am 
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Kirk Sorensen wrote:
I agree about Brayton, but remember that because an MSR would run a Brayton cycle indirectly, you can use working fluids other than helium. Nitrogen, argon, and CO2 are all viable options as well.


Argon isn't very attractive as a working gas in Braytons. It's a very good insulator. Good for protecting turbine blades, but not nice for gas coolers and heaters that the Brayton requires.

Probably the list is nitrogen, nitrogen-helium, helium, and CO2. Neon is theoretically another decent option, though perhaps practically a bit of an exotic one at the moment. Some have suggested neon as a gas coolant in stead of helium to solve problems in the design that helium's low atomic number causes.

I think nitrogen and S-CO2 are the most practical for non-nuclear (indirect cycle) application.


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PostPosted: Oct 23, 2013 11:26 pm 
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jagdish wrote:
Similarly isotopically ultra-pure 7Li as part of FLiBe will render the MSR economically unfeasible.
Not demonstrated. Recent strides in isotopic purifaction suggest this might be a rather inexpensive proposition.

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PostPosted: Oct 25, 2013 6:45 am 
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KitemanSA wrote:
jagdish wrote:
Similarly isotopically ultra-pure 7Li as part of FLiBe will render the MSR economically unfeasible.
Not demonstrated. Recent strides in isotopic purifaction suggest this might be a rather inexpensive proposition.


Any guess as to the cost per kg of Li7 with the new production techs? Are you referring to lithium crown ethers or vacuum distillation or something else?


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PostPosted: Oct 25, 2013 11:44 pm 
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I have an open mind. Has anyone tried to centrifuge liquid Li? It might work as 6&7 is quite a difference in mass! Otherwise I have suggested mass spectrum analysis. It should be possible to separate the Ions with mass nos 6&7. Economical feasibility is the problem anticipated.
As things stand, LWR's are losing out to temporarily cheaper shale gas in the US but doing well in China. Cheaper carrier salts are a must for the MSR.


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PostPosted: Oct 26, 2013 3:32 am 
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Liquids have too much self-interaction. Any seperated molten Li7 would quickly diffuse back into the rest of the molten Li. Liquid separation only works where you have different phases that don't interact rapidly, such as for liquid-solid and liquid-gas separation.


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PostPosted: Oct 26, 2013 4:43 am 
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Cyril R wrote:
KitemanSA wrote:
jagdish wrote:
Similarly isotopically ultra-pure 7Li as part of FLiBe will render the MSR economically unfeasible.
Not demonstrated. Recent strides in isotopic purifaction suggest this might be a rather inexpensive proposition.


Any guess as to the cost per kg of Li7 with the new production techs? Are you referring to lithium crown ethers or vacuum distillation or something else?

I believe the most recent work was a varient of crown esters.

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PostPosted: Oct 26, 2013 9:34 am 
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Yes, the Li crown ether (I think its ether not ester) appears highly promising with a simple low cost low temperature low pressure chemical. The Li crown ether is also less toxic than the other crown ethers (about the same toxicity as diesel). Still it's hard to get estimates of what this is going to cost.


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PostPosted: Oct 26, 2013 10:14 am 
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Berkeley came up with $83.33 per kg of enriched LiCl
using a series of highly speculative (and in my view optimistic) assumptions.
They required about 300 stages to get to 0.99995.

Ault et al, Lithium Isotope Enrichment: Feasible Domestic Enrichment Alternaitives
Report UCBTH-12-005, 2012-05-05.


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PostPosted: Oct 26, 2013 11:30 am 
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djw1 wrote:
Berkeley came up with $83.33 per kg of enriched LiCl
using a series of highly speculative (and in my view optimistic) assumptions.
They required about 300 stages to get to 0.99995.

Ault et al, Lithium Isotope Enrichment: Feasible Domestic Enrichment Alternaitives
Report UCBTH-12-005, 2012-05-05.


Ok, so that's around $500/kg Li7. Only some $9 million/GWe for a MSBR like system.

With such a low cost we've got some leeway. A system with twice the Li7 requirement and twice the cost of Li7 would still only net under $40 million/GWe which is peanuts.


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PostPosted: Oct 26, 2013 1:26 pm 
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Cyril R wrote:
Yes, the Li crown ether (I think its ether not ester)
You are correct. Thank you for the polite correction.

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PostPosted: Oct 26, 2013 1:28 pm 
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What needs to be researched on this issue? Is there any way to crowd fund this?

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PostPosted: Oct 26, 2013 2:05 pm 
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KitemanSA wrote:
What needs to be researched on this issue? Is there any way to crowd fund this?


Looks like all basic R&D is done. High separation factors are demonstrated, convenient salt forms have been identified (LiI and LiCl), and bench scale equipment has proven everythhing. Now it's time for the second "D", a demonstration project with a large number of stages to actually produce a small amount of high purity Li7.


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PostPosted: Oct 26, 2013 10:43 pm 
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This is such a cheap and hugely profitable investment for a small country.


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PostPosted: Oct 27, 2013 12:33 am 
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Couldn't a PWR or some other design of a reactor with a secondary steam loop (ie. the steam is not passed through the core) simply vent the live steam to atmosphere?

Although I don't imagine the environmentalists would like superheated steam being ejected from the top of the plant stack it would avoid having to fit desuperheaters or similar equipment.
Would require make up feedwater to be provided at a prodigious rate however.


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PostPosted: Oct 27, 2013 4:37 am 
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E Ireland wrote:
Couldn't a PWR or some other design of a reactor with a secondary steam loop (ie. the steam is not passed through the core) simply vent the live steam to atmosphere?

Although I don't imagine the environmentalists would like superheated steam being ejected from the top of the plant stack it would avoid having to fit desuperheaters or similar equipment.
Would require make up feedwater to be provided at a prodigious rate however.


This can be done, but there's only a small amount of water and steam in the steam system, and dumping steam means a temperature and pressure transient. It's a decent backup option but primarily you'd want to attempt a closed loop operation so that you can continue to operate the plant.

Are desuperheaters really needed, or can you sparge superheated steam in the condenser hotwell? This is what saturated steam cycles typically do with startup/shutdown. The enthalphy in the phase change is a lot bigger than in the superheat.


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