PeakOil is You
THE Uranium Supply Thread pt 4 (merged)
Re: Uranium Supply
by EnergyUnlimited » Thu 10 Jan 2008, 16:37:03
$this->bbcode_second_pass_quote('Dezakin', 'N')ow the problem with burning the 160 trillion tons of uranium and thorium in the crust in growth isn't running out of fuel, with a 1GW reactor demanding some 1 ton per year... its running out of heat dissipation capacity of the earth. If you make as much energy as the sun (say 10^16 watts?) you become dangerously close to altering the global climate without doing anything to the atmosphere at all, and your fuel resource will only last 16 million years.
You don't have to worry about these.
You will not be able to construct necessary infrastructure to utilize even small proportion of available total.
$this->bbcode_second_pass_quote('', 'I') dont think we're going to do that with nuclear reactors, partially because I expect solar will eventually become more economical and much of human industry will be space based, but its an interesting exercise.
I don't think we are going to develop solar sufficiently to cover even current level of use but there is a small chance that few percent of current consumption will be covered by that.
Nuclear will in all probabilities be used for several decades more, then uranium 235 will no longer be economical to use, MOX will run out and reactors will shut down.
Maybe several thorium breeders will be built to carry on here and there, but this is still open question.
At this time we are unlikely to see much industry left, either on Earth or in space.
Perhaps there will be some industry somewhere in space, as long as it is run by Aliens.
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EnergyUnlimited - Light Sweet Crude
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Re: Uranium Supply
by Dezakin » Thu 10 Jan 2008, 16:44:28
$this->bbcode_second_pass_quote('sch_peakoiler', 'A')nd how long should a thorium breeder run on HEU till it has bred enough U233 to start a normal cycle? about 10 years I guess? Lets take 10 years as a base.
so we take 100 PWRs, 400 tons of HEU, a bunch of thorium and start the cycle.
after 10 years we are able to refill them with Th+U233, and then they will breed at optimistic 1.02, so that we have another "fuel refill" after some 35 years. effectively 200 reactors after 35 years.
so we take 100 PWRs, 400 tons of HEU, a bunch of thorium and start the cycle.
after 10 years we are able to refill them with Th+U233, and then they will breed at optimistic 1.02, so that we have another "fuel refill" after some 35 years. effectively 200 reactors after 35 years.
Theres no way PWRs are going to breed at 1.02. The core geometry is wrong, LWR eats too many neutrons and isn't an optimal moderator. There was a light water breeder reactor designed but IIRC it wasn't like the PWRs on the market.
If I had access to say 400 billion dollars instead of invading some country I'd probably spend say 10 on the development of a molten chloride fast reactor for incinerating the plutonium and other actinides in spent fuel, and another 10 on the development of a molten fluoride reactor for meeting the global energy demands, and then spend I'd guess 2 billion each on the chloride fast reactors and about 1.5 billion on the fluoride thermal reactors.
The molten chloride incinerator reactors could run entirely on spent fuel plutonium, and we've got some 50 years of that stuff stockpiled up that we can send the uranium back to the enrichment plants for reintroduction into the market of PWRs (just basic fluoride volitility or using ANL pyroprocessing, so should be cheaper than the aqueous reprocessing methods for MOX fuel. No fuel fabrication requirement makes this cheaper also) The chloride reactors have a breeding ratio of over 1.4 IIRC (better than even LMFBR because of the xenon purging) and all the extra neutrons can go to the thorium blanket which continually strips out the U233 for marketing for the liquid flouride reactors.
The liquid flouride reactors have a breeding ratio of about 1.05, and as such really are converter reactors. They would cost less after development than a comperable PWR because of lower capital costs (running at atmospheric pressure negates the need of massive pressure vessels that can only be built by two steel foundries on the planet for a start, as well as having higher power density, smaller cores and higher thermodynamic efficiency) lower operating costs (no fuel fabrication requirement, much cheaper fuel costs, continuous revenue stream from marketable fission products like platinum metals, xenon, and radioisotopes.)
Also this would finally get people to shut up about the whole running out of energy meme when they realize how much energy is recoverable just by digging up some dirt in the backyard. (Cue in next doomy topic about overpopulation, ecological collapse, whatever. Theres allways some pessimistic horizon)
Strictly speaking, the chloride fast reactor is unnecissary. Fluoride thermal breeders can be started on enriched uranium, and the only industry demand would be for the initial fuel load. The chloride reactors are only aesthetically desirable for incineration of the spent fuel stockpile and optimal production of U233 for the market.
The fluoride reactors would consume 1/200th of a fuel thats 3 times as plentiful, produce 1/1000th of the waste that would have an average of a 30 year half life so that in 300 years the stuff is less radioactive than the ore it came from.
$this->bbcode_second_pass_quote('', 'W')ell: forget breeders completely and stick with SWU, old tails, MOX, Mining, PWR
:)That, IMHO, is sufficient for the fuel cycle and energy demands of civilization, though not aesthetically pleasing or optimally efficient. I doubt things will play out with any breeder reactors in the future because of the initial startup risk, unless some government decides they're making a strategic decision for energy security.
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