Energy From Thorium Discussion Forum

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 Post subject: Re: Lithium-7
PostPosted: Aug 07, 2015 10:53 am 
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E Ireland wrote:
What 7Li enrichment is actually required for say a DMSR?
(I understand as high as possible is wanted for tritium containment reasons, but what do we actually need).


Depletion, not enrichment. MSRs need lithium depleted to about 50ppm lithium-6.


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 Post subject: Re: Lithium-7
PostPosted: Aug 07, 2015 2:19 pm 
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Kirk Sorensen wrote:
E Ireland wrote:
What 7Li enrichment is actually required for say a DMSR?
(I understand as high as possible is wanted for tritium containment reasons, but what do we actually need).


Depletion, not enrichment. MSRs need lithium depleted to about 50ppm lithium-6.


So that is about? 99.995% pure 7Li?
Oh good, that is the same as the FHR programme requires.
There might be more chance of a reasonable plant producing that.


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 Post subject: Re: Lithium-7
PostPosted: Aug 07, 2015 2:47 pm 
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E Ireland wrote:
Unfortunately the only really available-in-the-west technology of crown ether extraction is apparently not very amenable to the SWU approximation, you can't stack it really.


Its may be more optimal to use 2 different technologies, first a "quick and dirty" then a "boutique" process. Possibly a chemical process to start, then a physical process to top it off.


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 Post subject: Re: Lithium-7
PostPosted: Aug 07, 2015 8:21 pm 
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The stated enrichment/depletion level is apparently low enough to reach using the chemical technology - albeit with an enormous tails fraction (with Lithium so cheap and its uses normally not caring about isotopic make-up I suppose this is a reasonable route to take).

The price then becomes basically dependent on what sort of price cuts you can get from the crown ether extractant from mass production.
Also have to have a discussion about whether it would be worth recovering the Lithium from old DMSR salt.
Extracting the uranium is one thing but the lithium is a far more involved process.

30,000kg of 7Li in a Reference DMSR. $500/kg is only $15,000,000 - which is nothing. Works out about 7.6 cents per MWh


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 Post subject: Re: Lithium-7
PostPosted: Aug 07, 2015 11:27 pm 
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Is there a consensus on the method of separation? Can we really have an estimate? A mass spectrum is one way I am convinced will work.


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 Post subject: Re: Lithium-7
PostPosted: Aug 08, 2015 7:46 am 
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jagdish wrote:
Is there a consensus on the method of separation? Can we really have an estimate? A mass spectrum is one way I am convinced will work.


Only thing I can find out the cost is this paper.

EM Separation will struggle to make $500/g unfortunately.


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 Post subject: Re: Lithium-7
PostPosted: Aug 08, 2015 8:36 am 
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Laser isotope separation may be useful. Short write up of technology from LLNL.
https://str.llnl.gov/str/Hargrove.html


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 Post subject: Re: Lithium-7
PostPosted: Aug 08, 2015 8:40 am 
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LNLL website talks about cost being lower than centrifuges for uranium and having wide ability to separate isotopes of different elements. No talk of lithium but does talk about calcium.


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 Post subject: Re: Lithium-7
PostPosted: Aug 08, 2015 9:08 am 
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michaelw wrote:
LNLL website talks about cost being lower than centrifuges for uranium and having wide ability to separate isotopes of different elements. No talk of lithium but does talk about calcium.


People have been talking about doing AVLIS and other laser isotope separation methods for years. It has become a bit like fusion in that regard.


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 Post subject: Re: Lithium-7
PostPosted: Aug 08, 2015 12:13 pm 
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LNLL did more than talk. Like many things nuclear(MSR, Integral Fast reactor), the funding was cut when the technology was close to commercial viability. Frustrating to think what might have been.
mike


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 Post subject: Re: Lithium-7
PostPosted: Aug 08, 2015 12:15 pm 
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LLNL


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 Post subject: Re: Lithium-7
PostPosted: Aug 08, 2015 4:23 pm 
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E Ireland wrote:
michaelw wrote:
LNLL website talks about cost being lower than centrifuges for uranium and having wide ability to separate isotopes of different elements. No talk of lithium but does talk about calcium.


People have been talking about doing AVLIS and other laser isotope separation methods for years. It has become a bit like fusion in that regard.


It is quite feasible, compared to sustained electricity generation with fusion.

Its just that physics and chemistry haven't given us a decent volatile lithium compound, so we have to get vacuum and some temperature with the elemental stuff. Bit of a pain, but no reason it shouldn't work. Laser can be very selective so selectivity might make up some of that expense of heated vacuum equipment and costly lasers. It might be interesting to use crown ethers to get to 99-point-something, then final enrichment to 99.999% with lasers.


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 Post subject: Re: Lithium-7
PostPosted: Aug 09, 2015 6:31 am 
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Natural Lithium comes with a neutron poison 6Li. It does not function as fuel or even the moderator, only a component of the solvent. At the time when the nuclear power is getting a beating on price, among other things, it is not worthwhile to push it through a costly isotope separation process, yet to be commercially developed.
To get the molten salt technology going at this stage, we have to cut down costs. We have to forego 7Li and the graphite moderator to cut volume and cost.
The initial successful nuclear technology has been the LWR. Even the PHWR, which substituted Deuterium enrichment to replace uranium enrichment is only an also ran. Graphite moderated voluminous rectors are also on the way out.
It is time to
1. Avoid high pressure and costly reactor vessels so that people who want it can get it easily.
2. Re-use the used LWR fuel to get waste disposal points.
Unmoderated MSR's using the recycled LWR fuel is the only way for MSR technology to get a foot inside the energy door.


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 Post subject: Re: Lithium-7
PostPosted: Aug 09, 2015 6:59 am 
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If Graphite and Heavy Water reactor reacctors are also rans - what are Fast Reactors?

There is one fast reactor in operation - and that is in Russia.

There are many more graphite and heavy water reactors in operation.


That said, I see little point pushing beyond 50ppm 6Li. We need it to be cheap enough to just discard the salt.


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 Post subject: Re: Lithium-7
PostPosted: Aug 09, 2015 8:32 am 
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What's the cost difference between 10 ppm Li6 and 50 ppm?


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