Comments on: The Atomic Show #121 – LFTR with Kirk Sorensen and Charles Barton

By: Aaron Rizzio

Aaron Rizzio — Fri, 30 Jan 2009 22:23:22 +0000

link to MIT thesis on S-CO2 turbine cycle (PDF)

By: Aaron Rizzio

Aaron Rizzio — Fri, 30 Jan 2009 22:16:03 +0000

I don't know why CO2 would not be vary nearly as useful as helium in gas turbine reactors. I ran across an interesting engineering thesis paper from MIT describing a super-critical gas turbine with ~42% efficiency. The only significant trade-off would be operating temperature as CO2 tends to sublimate graphite (a problem for TRISO?) at high temperatures (above ~600 centigrade), but operating efficiencies of 42% are achievable with super-critical CO2 at this (relatively) low temperature. In LFTRs lead would be a good intermediate heat transfer medium between the circulating fuel and S-CO2.

By: Rod Adams

Rod Adams — Mon, 19 Jan 2009 23:29:55 +0000

Bill – it would if we could figure out how to keep the process running for more than a second or two at a time.

By: Bill Woods

Bill Woods — Mon, 19 Jan 2009 21:39:45 +0000

Time to ramp up the synthesis of helium from hydrogen, I guess. If only the process didn’t produce so much waste heat!

By: Aaron Rizzio

Aaron Rizzio — Sat, 17 Jan 2009 21:14:40 +0000

Total world demand for helium was, according to Worldwide Helium Air Products , 165 million nm3 (normal meters cubed, ~24,000 metric tons) in 2007, and is estimated to grow at around 4% per year; 3/4 of world production is from the US which is now drawing down its long held strategic helium reserve (of 170,000 metric tons a decade ago) as natural gas fields reportedly show helium decline of 10-15% per year. According to a 2000 National Academy of Sciences report , the total U.S. helium resources will disappear by 2035–probably sooner.

Helium has doubled in price just since 2000, according to Scientific American this is due to demand from MRI medical diagnostics. How much helium would a standard 1000MW(th) LFTR require or for that matter a GA model GT-MHR or an Adams, Eskom, or MIT design PBMR?

http://en.wikipedia.org/wiki/Helium

By: Rod Adams

Rod Adams — Wed, 14 Jan 2009 00:50:23 +0000

@ondrejch – you are correct for now. However, I am more concerned about what happens to the price of the gases if there is a significant new demand. With N2, the supply is essentially unlimited, though there is a certain cost of new machinery to produce the high purity product.

The same is not true of the other gases. The overall supply is actually quite limited, but right now it balances the demand. That equation changes if there is a large new demand – like thousands of Adams Engine type machines.

By: ondrejch

ondrejch — Tue, 13 Jan 2009 20:56:03 +0000

Hi Rod et al., thanks for a great show! I looked up the high purity gases prices, and it seems they are not significantly different. http://www.cehs.siu.edu/gas/price_list.htm
http://www.alibaba.com/product-gs/211539843/High_purity_oxygen_hydrogen_helium_neon.html

By: Aaron Rizzio

Aaron Rizzio — Sun, 11 Jan 2009 07:21:03 +0000

Thanks for this show I've been following Kirk Sorensen's web publications on the LFTR concept for several months now; recently I came accross his ppt presentation file linked to the Nov 3 workshop he participated in that James Hansen mentioned in his "Open Letter to Obama". I was wondering if Mr. Sorensen has a text or audio file of his presentation to go along with it? The idea of submersible LFTRs are probably more practical than large scale off-shore wind projects such as the 5GW (capacity) Ocean Energy Institute proposal for the Maine coast. I can see 100-500MW(e) mini-sub sized units manufactured at Portsmouth Naval Shipyard and either towed or self propelled to an anchorage in the littoral zones of the world adjacent to convenient grid tie-ins.

By: Jagdish

Jagdish — Wed, 07 Jan 2009 10:02:52 +0000

A very enlightening discussion that brings out various of their pet LFTR concept. There are some interesting ideas which need to be tried out even in other type of reactors.
Liquid fluoride/salt coolant is one such idea. I sometimes wonder why it has not replaced sodium or water as coolant in the fast and even thermal reactors so far.It could avoid sodium fires in fast reactors or reduce pressure in thermal reactors improving safety in both and reducing costs in thermal reactors. Some fluoride combinations could be more neutron economic than light water.
Thorium has higher conversion to fissile isotopes than uranium and with some fissile initial input makes thermal breeders or near breeders, resulting in higher burn up and longer time between fuel changes or reprocessing.
Fluid fuel enables easy removal of volatile fission products like Xenon. Some fissile isotopes fluorides may also escape but could be recovered and put back in.
Removal of neutron hungry fission products is very important for continued criticality and there are many Lanthanide’s creating such problems including Samarium. The boiling and melting points of solvent salts,fission products and fuel fluorides (excluding UF6) are so interlaced that it is not feasible to separate them physically. This may have been unsaid reason for lack of progress in the technology in the last few decades.
The best way to separate Lanthanide’s from Actinides that I have read about is use of 3.5N Hydrochloric acid to dissolve the Lanthanides leaving a residue of thorium and uranium, used by Bharat rare earths.This, as pointed out in the talk, requires a conversion from fluorides. Let the chemists consider the electrolytic refining in fused fluorides like Aluminum refining.