FLiBe with 99.995% 7Li

Torres
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FLiBe with 99.995% 7Li

Post by Torres » Nov 11, 2014 5:11 pm

How feasible will be to use a molten salt reactor to purify 99.9% 7Li to 99.995% 7Li by injecting small quantities of 99.9% 7Li and leave the reactor decompose the 6li up to 99.995% 7Li purity?

Lars
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Re: FLiBe with 99.995% 7Li

Post by Lars » Nov 11, 2014 6:22 pm

You would increase from 0.005% Li-6 to 0.1% Li-6. In other words, 20x as much Li-6. Neutron losses to capture by Li-6 would be 20x as high. This is an extraordinarily expensive way to do isotropic separation. You would have to feed in plenty of fissile (like U235) to compensate. For each atom of Li-6 removed this way you would need to add 1.2+ atoms of U235. Exchanging isotropic enrichment of uranium (235/238) instead of lithium (6/7) is a poor trade indeed.

Torres
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Re: FLiBe with 99.995% 7Li

Post by Torres » Nov 17, 2014 10:20 am

If the fuel is in liquid form maybe I may inject very small quantities of the the less enriched Li to control core reactivity and enrich Li at the same time. As I understand, 1g of 235U is $50 and can finishing the enrichment 1 kg of Li. This enriched Li will increase end of life value of the reactor.

At 1.05 separation capacity it looks that this activity to enrich from 99.9% to 99.995% is very hard and costly to achieve.

I find this paper in the internet about new Li separation techniques: http://jolisfukyu.tokai-sc.jaea.go.jp/f ... /4_10.html

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Kirk Sorensen
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Re: FLiBe with 99.995% 7Li

Post by Kirk Sorensen » Nov 17, 2014 12:15 pm

Not enriched, depleted. Enriched lithium has >8% lithium-6. Depleted lithium has <8% lithium-6. The lithium we need for MSRs is highly depleted.

Torres
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Re: FLiBe with 99.995% 7Li

Post by Torres » Nov 17, 2014 9:20 pm

Thank you for the correction.

Lars
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Re: FLiBe with 99.995% 7Li

Post by Lars » Nov 19, 2014 3:20 pm

Torres wrote:If the fuel is in liquid form maybe I may inject very small quantities of the the less enriched Li to control core reactivity and enrich Li at the same time. As I understand, 1g of 235U is $50 and can finishing the enrichment 1 kg of Li. This enriched Li will increase end of life value of the reactor.

At 1.05 separation capacity it looks that this activity to enrich from 99.9% to 99.995% is very hard and costly to achieve.

I find this paper in the internet about new Li separation techniques: http://jolisfukyu.tokai-sc.jaea.go.jp/f ... /4_10.html
1 gram of U235 would be 1/235 moles of extra neutrons in a very good reactor. This would allow removal of 1/235 moles of Li-6 which would enrich 1/235/.095% = 4.5 moles of lithium. This is 31 grams of lithium. But not all of the u235 fissioned so there will be some loss of performance in your reactor from that. Also, you don't get to add 100% u235. Legally it will be 20%u235 and 80%u238. The U238 won't perform as well as Th232 in the reactor so there is going to be more losses there. Finally, no one makes 20%LEU today so you have a sourcing problem in addition. I'm not absolutely certain that this isn't going to be a productive approach but I'm pretty sure it isn't the path to pursue.

Torres
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Re: FLiBe with 99.995% 7Li

Post by Torres » Nov 19, 2014 8:49 pm

Thank you Lars.

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Eino
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Re: FLiBe with 99.995% 7Li

Post by Eino » Jan 03, 2015 1:53 pm

Question:

I've been reading about these LFTR reactors for some time (as a layman). I caught wind of something that just never occurred to me the other day. I was reading a post and it stated that the stuff (FLiBe) was very expensive. Is this currently manufactured for industrial processes or would it need to be "custom" made for new power plants?

This link points at problems.

http://www.the-weinberg-foundation.org/ ... m-problem/

Cyril R
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Re: FLiBe with 99.995% 7Li

Post by Cyril R » Jan 03, 2015 4:30 pm

FLiBe is the most neutronically and also thermal-hydraulically efficient option. So it receives much attention. But, it isn't strictly necessary. There are many options available, more so for molten salt fuelled reactors than molten salt cooled reactors, in terms of still retaining decent negative feedback coefficients (the less neutronically optimal salts absorb more neutrons so have more positive void coefficient).

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Re: FLiBe with 99.995% 7Li

Post by KitemanSA » Jan 13, 2015 12:23 pm

Kirk Sorensen wrote:Not enriched, depleted. Enriched lithium has >8% lithium-6. Depleted lithium has <8% lithium-6. The lithium we need for MSRs is highly depleted.
seems to imply that there is a convention that the terms "enriched" and "depleted" only apply to the minor component. Is that a real convention? Aren't we really seeking "enriched" Li7?
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Kirk Sorensen
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Re: FLiBe with 99.995% 7Li

Post by Kirk Sorensen » Jan 13, 2015 1:56 pm

Yes, the convention applies to the minor component.

Lars
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Re: FLiBe with 99.995% 7Li

Post by Lars » Jan 13, 2015 3:46 pm

Eino wrote:Question:

I've been reading about these LFTR reactors for some time (as a layman). I caught wind of something that just never occurred to me the other day. I was reading a post and it stated that the stuff (FLiBe) was very expensive. Is this currently manufactured for industrial processes or would it need to be "custom" made for new power plants?

This link points at problems.

http://www.the-weinberg-foundation.org/ ... m-problem/
Li7 is used to balance acidity in LWRs but the volume they need is much smaller than required for LFTRs.

E Ireland
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Re: FLiBe with 99.995% 7Li

Post by E Ireland » Jan 13, 2015 9:23 pm

Only PWRs - BWR type reactors run with entirely neutral water chemistry as they do not use Boric acid to control reactivity.

Cyril R
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Re: FLiBe with 99.995% 7Li

Post by Cyril R » Jan 14, 2015 3:50 am

Lars wrote:
Eino wrote:Question:

I've been reading about these LFTR reactors for some time (as a layman). I caught wind of something that just never occurred to me the other day. I was reading a post and it stated that the stuff (FLiBe) was very expensive. Is this currently manufactured for industrial processes or would it need to be "custom" made for new power plants?

This link points at problems.

http://www.the-weinberg-foundation.org/ ... m-problem/
Li7 is used to balance acidity in LWRs but the volume they need is much smaller than required for LFTRs.
The Li-7 concentration is also lower for them. There don't appear to be any 99.995% Li7 producers. If it exists that pure then its legacy supply. Not sure if this is for technical reasons (I can't imagine any) or for economical reasons (likely).

Like Ed says it is for PWRs. Neutral water chemistry is one of the selling points of BWR over PWR.

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Tim Meyer
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Re: FLiBe with 99.995% 7Li

Post by Tim Meyer » Jun 03, 2016 10:00 am

If I may, but given the importance of isotopic separation of lithium, perhaps you would deign to look at the ionic liquids methods that were published. Using expensive neutrons to convert 6Li to 3H may be feasible but not desirable.

The new ionic liquids (ILs) separation methods look very promising. I believe members ought to review at:

Post subject: Re: Lithium-7 Posted: May 30, 2016 3:17 pm

Do ILs look good? Ups and downs?

Cyril R and others point here to the optimum properties of FLiBe and then give up on achieving HD lithium (99.995% or better). As best as I can tell, the new IL methods with commercially available extractors SOLVES the HD lithium supply problem; and given what Dr. Vidal at Materion Brush has said, there's plenty of FLiBe to meet demand from FE LFTRs. Done.
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