[ExI] cure for global warming.
jonkc at bellsouth.net
Mon Dec 27 20:40:26 UTC 2010
On Dec 27, 2010, at 1:56 PM, Eugen Leitl wrote:
> Any preparative neutron source can be used to breed plutonium. Thorium molten-salt is definitely
> not proliferation-resistent.
To hell with molten-salt, I'm talking about Liquid Fluoride Thorium Reactors (LFTR) where not just the neutron moderator and the coolant is in liquid form but the fuel is too. A LFTR reactor needs almost all its neutrons just to keep going, so if you try to steal them to irradiate U238 to make plutonium the LFTR reactor chain reaction will stop.
I'm going to quote from part of a post I sent to the list about 6 months ago.
Consider the advantages:
*Thorium is much more common than Uranium, almost twice as common as Tin in fact. And Thorium is easier to extract from its ore than Uranium.
*A Thorium reactor burns up all the Thorium in it so at current usage that element could supply our energy needs for many thousands, perhaps millions of years; A conventional light water reactor only burns .7% of the Uranium in it.
* To burn the remaining 99.3% of Uranium you'd have to use a exotic fast neutron breeder reactor, Thorium reactors use slow neutrons and so are inherently more stable because you have much more time to react if something goes wrong. Also breeders produce massive amounts of Plutonium which is a bad thing if you're worried about people making bombs. Thorium produces an insignificant amount of Plutonium.
* Thorium does produce Uranium 233 and theoretically you could make a bomb out of that, but it would be contaminated with Uranium 232 which is a powerful gamma ray emitter which would make it suicidal to work with unless extraordinary precautions were taken, and even then the unexploded bomb would be so radioactive it would give away its presents if you tried to hide it, destroy its electronic firing circuits and degrade its chemical explosives. For these reasons even after 65 years nobody has even tried to make bomb out of Uranium 233.
*A Thorium reactor only produces about 1% as much waste as a conventional reactor and the stuff it does make is not as nasty, after about 5 years 87% of it would be safe and the remaining 13% in 300 years; a conventional reactor would take 100,000 years.
*A Thorium reactor has an inherent safety feature, the fuel is in liquid form (Thorium dissolved in un-corrosive molten Fluoride salts) so if for whatever reason things get too hot the liquid expands and so the fuel gets less dense and the reaction slows down.
*There is yet another fail safe device. At the bottom of the reactor is something called a "freeze plug", fans blow on it to freeze it solid, if things get too hot the plug melts and the liquid drains out into a holding tank and the reaction stops; also if all electronic controls die due to a loss of electrical power the fans will stop the plug will melt and the reaction will stop.
*Thorium reactors work at much higher temperatures than conventional reactors so you have better energy efficiency; in fact they are so hot the waste heat could be used to desalinate sea water or generate hydrogen fuel from water.
* Although the liquid Fluoride salt is very hot it is not under pressure so that makes the plumbing of the thing much easier, and even if you did get a leak it would not be the utter disaster it would be in a conventional reactor; that is also why the containment building in common light water reactors need to be so much larger than the reactor itself. With Thorium nothing is under pressure and there is no danger of a disastrous phase change so the expensive containment building can be made much more compact.
If you're interested in this technology this might be a good place to start:
John K Clark
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