Energy From Thorium Discussion Forum

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PostPosted: Jun 03, 2018 6:00 pm 
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Joined: Apr 25, 2011 10:01 pm
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I found this:

https://liquidfluoridethoriumreactor.gl ... -products/

Fission of 1000 kg U-233 produces several chemicals essential for industry, readily extracted from a LFTR or any other Molten Salt Reactor, including:

150kg xenon

125kg neodymium

20kg medical molybdenum-99

20kg radiostrontium, zirconium, rhodium, ruthenium, and palladium.

(unknown kg) Iodine-131 is used to treat cancers of the thyroid.

(unknown kg)Thorium-229 for cancer treatments, decays to Bismuth-213, which decays through alpha emission (unlike most of the fission products that decay through beta emission). By binding Bi-213 to an antibody, it can be directed swiftly to a cancerous cell. The alpha decay of the Bi-213 then has a high probability of killing the cancer cell. (Very small amount/treatment, but decays fast to Bi-209.)


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PostPosted: Jun 03, 2018 6:00 pm 
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Joined: Apr 25, 2011 10:01 pm
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I am curious about the fission products, what are they and what percentage of the waste stream would they each be?

Does anyone know of a resource which has an itemized breakdown?


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PostPosted: Jun 05, 2018 5:36 am 
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Joined: Apr 25, 2011 10:01 pm
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I think this may be the data I was looking for but I am not sure how to read it.

https://www-nds.iaea.org/wimsd/fpyield.htm#T1

https://www-nds.iaea.org/sgnucdat/c3.htm

https://wwwndc.jaea.go.jp/cgi-bin/FPYfig


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PostPosted: Jun 06, 2018 10:08 am 
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Joined: Jan 16, 2012 7:15 am
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Matthew,
You need a time-dependent table of cumulative fission yields, because the isotopic mix of the “waste” changes over time. I couldn’t find such a table on the net, so I made one.
You can download the View235QC file at http://iffydata.org/data-output/ This file isn’t designed to answer your question(s), but it’s more applicable than the sources in your post. View235QC has a bunch of descriptive fields that make data mining more productive.

Another file, AllSlow, has fission product evolution for 233-U (and nine other fuels), but its neutron capture model isn’t yet specific to the Thorium cycle. That’s on my ToDo list. In any case, neutron capture is a minor factor in the “interesting” fission products. View235QC can show that via analysis test 8 below.
For a more accurate picture, you need to combine the AllFast data and chose a “speed” for your notional MSR (0-100% fast neutron fissions). This is probably overkill at the moment.

Some analysis suggestions: I use Excel, but I tested these data - a while ago - on freeware Calc.
1) Set the Timestep to 27 (2.0 e+27 seconds). This would assume you clean the salt every four years, which might be Thorcon’s plan. You can capture shorter lived isotopes by processing the salt more often, but these data don’t readily support that kind of analysis.
2) Set the Capture filter to Yes to avoid double counting. The “No” data is just there for QC of my neutron capture algorithm.
3) Sort by Norm (normalized yield), descending. At the top, 134-Xe shows its absolute Yield to be about 10 million atoms present in the waste tank after four years of operation. For the relative proportion, divide Norm (0.0078) by two! The sum of Norm at every timestep is 2.00, since two atoms are created when each fuel atom is split. (My reactor runs at one fission per second.)
4) Filter out the really rare isotopes (less than 1 ppm) by setting Norm to values > 0.00002. This reduces the “relevant” isotope list from 1322 to 154.
5) Set the Time_Bin to 6, to see the seven LLFP (long lived fission products). Other settings will highlight shorter-lived isotopes.
6) Set the Rung to 20 to see the shadowed isotopes. Without neutron capture, these have negligible yields. An isotope’s Rung value is its location on the Energy Ladder – basically the number of excess neutrons that must decay for the nucleus to achieve stability. (Fractional numbers denote isomers.) There is one Rung 0 isotope at each atomic weight. Most decay chains drain into these. Filter out 0 and 20 to see all the unstable isotopes in the mix.
7) The Class field bins the neutron poisons by Roman numeral plus Z (Zero barns). Class I (1-9) and Class X (10-99 barns) won’t change much if you switch the Capture field from Yes to No. Class C and M will, but you can see the differences better at 8, 17, and 34 years (Timesteps 28-30).
8) Make a subset worksheet of the list of 154. Make a Pivot table of that, then a Line chart with Timestep as the page filter, AtWt on the x-axis, Capture as the legend, and (sum of) Norm as the data values. The sums should match the cumulative yield numbers in the sources you mention in your post – if their waste is 4 years old!
9) Change the chart style to Stacked Column, and add Nuclide to the columns. This will show “active” decay chains, where more than one isotope exist. You can zoom in with Terrain as a page filter. Set this filter to Heavy to see atomic weights 125-160 in greater detail.

Note that for an MSR, the waste will be in two locations, in the "old" salt and in the off-gas tanks. 90-Sr and 137-Cs, in particular, will be in both places. Analyzing off-gas options is also on my ToDo list. Someday, you can find that at http://iffydata.org/
In terms of “waste” separation, can’t we just stick electrodes in the salt stream and try various voltages? I’d like to see an electro-plating analysis. I worry how "sticky" Li, Be and U are, though.


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PostPosted: Jun 06, 2018 7:23 pm 
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Thank you.


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