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Hello all,
I am someone who has been interested in the future of nuclear energy for awhile now. Recently a new type of nuclear reactor came to my attention, one I believe has a great deal of promise for humanity's future, so knowing TL is full of techies who might be interested in it, and after a thorough search revealed no other posts on this topic, I decided to make one. It is called a LFTR, a Liquid Fluoride Thorium Reactor, and it has many advantages over the current Pressurized Water Reactors (PWRs) which produce 99.9% of all nuclear power today.
In a nutshell:
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The LFTR is a better design than the current PWRs for a number of reasons:
1) PWR's, as their name implies, hold water in a highly pressurized state. Water is held between 75-150 atmospheres of pressure so that it's boiling point can be raised above 300C, which is the only way to generate enough heat to make it viable for generating electricity. Since the LFTR uses molten salt instead of water as a coolant, and since molten salt does not need to be pressurized to reach high temperatures, the reactor can be operated at normal pressures, mitigating the possibility of explosions, meltdown, and environmental contamination. This is the single greatest advantage of the LFTR over current PWR technology.
2) Since the reactor operates in the 700C range, the temperatures are hot enough to use a gas turbine instead of the steam turbines other reactors use, vastly increasing efficiency. Because LFTRs use a gas turbine, the excess heat generated can be used to de-salinate seawater, essentially for free. This means that in addition to generating power, a LFTR can provide fresh drinking or irrigation water, instead of one or the other with traditional nuclear de-salination.
3) LFTR, as the name implies, uses a fuel known as Thorium, which is so abundant in the earth's crust that you can literally mine a ton of ordinary rock, and extract enough Thorium from that rock to power your life for 5 years. 5000 tons of Thorium would provide the entire planet's energy needs for a year, and there is over a million tons of Thorium in known deposits already on earth, and probably several times that much still undiscovered.
4) LFTRs do not produce the "spent fuel" problem of ordinary solid fuel reactors like PWRs. Because the fuel is a liquid it can be fully burnt up in the reactor, so storage of spent fuel is not necessary. Furthermore the projected transuranic waste of a 40MW "mini" reactor produced over ten years is anticipated to be only a few millionths of a gram. This is teeny tiny amounts of pollution.
5) LFTRs can burn up existing nuclear waste as part of their fuel cycle. So if you're concerned about nuclear waste and the Yucca Mountain depository, build LFTRs instead and burn it all up!
6) Since LFTRs do not use water as a coolant, they do not need to be located near a major river like PWRs. States like Utah or Nevada can go on a LFTR building spree, something they cannot do with PWRs. Furthermore, developing countries can build them regardless of their climate and water availability, and as mentioned above can even use them to generate drinking water or water for crops.
7) LFTRs were originally conceived in the 1950s as part of a "Nuclear Bomber" program the Air Force had. As such they were designed to power an aircraft, something a PWR could never hope to do for a number of reasons. Because of this LFTRs are incredibly safe. It is a dynamically stable system, meaning it self-regulates. As the salt heats up, it expands, touching more of the pipe surface. This begins to cool the salt, and it begins to contract, heating it up, and the cycle repeats. It is walk away safe. Unlike PWRs nuclear safety technicians could walk out the door and turn out the lights, and it would keep running safely without risk until it used up all its fuel.
8) A "freeze plug" is used as a passive safety system in the LFTR. A fan blows a cool gas over a portion of pipe containing the salt, freezing it solid. In the case that something goes wrong and power is lost in the reactor, the fan stops blowing, the frozen salt plug melts, and all the molten salt in the reactor drains down naturally by gravity into a storage container designed for that purpose. No explosions, no meltdowns, no radioactive contamination.
9) LFTRs are extremely proliferation resistant, overcoming another of the major objections to nuclear power as it is currently practiced. The reason for this is chemisty. Unlike all other nuclear reactors today which use either the U-235 or the U-238-->Pu-239 fuel cycle, the LFTR operates on the Th-232-->U-233 fuel cycle. This means that the LFTR is a breeder reactor like Liquid Metal Fast Breeder Reactors (LMFBR) but unlike LMFBRs it does not use fast neutrons, it uses thermal neutrons, which makes fission much easier to achieve, and the fluoride salt used in the LFTR is much safer and less reactive than the liquid sodium used in the LMFBRs. Uranium-233 is useless for making bombs, since it has a hard gamma emitter in its decay chain. This is manageable for containment and disposal but not for bombs that have to be designed and that sit in storage. The gamma emissions from the decay of U-233 will:
a) Damage your bomb's circuits
b) Kill your staff working on it
c) Show everyone in the world with gamma ray detectors where your bomb is (pretty much every developed country has them on satellites by now.)
Sound too good to be true? It did to me too when I first heard about it. Here are some links I recommend you check out if you want to learn more.
Links:
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Finally if you want to get involved in trying to make this a reality you can check out Energy From Thorium, the largest Thorium advocacy organization I'm aware of.
Energy From Thorium:
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Flibe Energy is the only company I know of in the United States currently pursuing LFTR. If you have a few billion to spare, consider helping them out.
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China is officially pursuing LFTR:
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LFTRs built in years past:
The Aircraft Reactor Experiment, a 2.5MW LFTR designed to power a bomber aircraft. Made obsolete by ICBMs.
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The Molten Salt Reactor Experiment at Oak Ridge National Laboratory.
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In a nutshell, if this was conceived of in the 1950s, why did they go and make all those PWRs?
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On January 25 2012 10:32 EtherealDeath wrote:
In a nutshell, if this was conceived of in the 1950s, why did they go and make all those PWRs?
Excellent question, and this is covered extensively in those two documentaries, but the short answer is that Thorium is useless for making a nuclear weapon, and in the 1950s at the height of the Cold War they wanted to generate power and make bombs, so they chose U-235 and the U-238-->Pu-239 fuel cycles, both of which can be used for electricity and for bombs.
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I see you're from China EtherealDeath. You may be interested to know that China is currently the only country in the world actively developing LFTR technology. They anticipate their prototype LFTR coming online by 2022, and it is being spearheaded by Jiang Mianheng, the son of Jiang Zemin, who holds a PhD in Electrical Engineering from Drexel.
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This all just seems wonderful. :D
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I like how the thread starter actually knows what he is talking about and responding in a professional manner.
Nice thread, thanks for sharing and explaining 
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mmm, this does sound too good to be true. But it also sounds plausible.
If this stuff works out it could be a huge leap in electricity supply. The biggest issue with green power is that lack of proper storage systems which nuclear power totally circumvents. Time for a read...
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Sounds to good to be true but if it is true will be a good energy source untill we master fusion.
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On January 25 2012 10:47 Zaros wrote:
Sounds to good to be true but if it is true will be a good energy source untill we master fusion.
I used to be the biggest fusion guy. I would read or watch anything I could find on it. Now I am inclined to agree with you. LFTR now, fusion when we master it (probably a few more decades,) matter-antimatter annihilation sometime after that.
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In a nutshell, I bet this would get more responses if it was titled "girl invents unlimited power source." However the topic has been around here before, maybe just buried in other threads.
Truthfully I'd think that in the past these fission reactors with thorium weren't fully technologically feasible. It's too optimistic to say otherwise, there would have been years of development needed in the past before anything could really be built, while getting started on uranium fission plants was quicker. The understanding of how the nuclear reactions would work was there, but overall level of technology was such that cost would have been prohibitive and smaller scale reactors which could be built today simply wouldn't have been doable. It's equally important to remember the political pressure on nuclear power has always immense. A reactor design that would not cleanly lead to enrichment of fuel for weapons and was out-lobbied never was given the opportunity for significant research and development. Of course, it is regrettable the visionary choice wasn't made back then because we would probably all be better off now.
From where things stand today, real investment in this technology ought to yield results much more quickly. First world countries like the US could solve the problem effectively permanent electrical power (not going to run out of thorium) at costs that aren't discouraging, especially compared to other renewables. The main obstacle is that the current economic state of the world and political priorities of first world countries make any large scale investment in energy difficult. If the entire scientific and energy community was behind a new age of investment in nuclear power it would be tough enough, let alone competing with other energy lobbies and the effect of dividing up already small amounts of funds and subsidies that would go towards solar/wind/other renewable energy.
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On January 25 2012 10:51 Crazy Eddie wrote:
Truthfully I'd think that in the past these fission reactors with thorium weren't fully technologically feasible.
LFTRs are not an unproven technology. They have been built before. The Molten Salt Reactor experiment ran for over 3 years. Here are a few examples of LFTRs in the past:
Links:
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I remember reading from one of those periodic tables w/ descriptions of elements that thorium ores were super abundant and could represent energy potential far greater than uranium. Glad to see it's being implemented, the question is when will it be widespread enough that coal, oil, and natural gas are no longer needed? And will the U.S. government be receptive to a power source that is not oil and that could unemploy its citizens (although the construction of the facilities will employ people at first).
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On January 25 2012 10:51 Crazy Eddie wrote:
From where things stand today, real investment in this technology ought to yield results much more quickly. First world countries like the US could solve the problem effectively permanent electrical power (not going to run out of thorium) at costs that aren't discouraging, especially compared to other renewables. The main obstacle is that the current economic state of the world and political priorities of first world countries make any large scale investment in energy difficult. If the entire scientific and energy community was behind a new age of investment in nuclear power it would be tough enough, let alone competing with other energy lobbies and the effect of dividing up already small amounts of funds and subsidies that would go towards solar/wind/other renewable energy.
And unfortunately that is politics the greatest disaster in humanities existence, i wonder if a name change and some PR work for nuclear energy would help at all?
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On January 25 2012 10:42 Grobyc wrote:I like how the thread starter actually knows what he is talking about and responding in a professional manner. Nice thread, thanks for sharing and explaining
Thanks for the nice compliment! It's my pleasure!
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This seems like one of those "to good to be true" things. If it really can do all that i would love to see a serious investment in the USA. OP because you knew that research was being done in china do you know if there is anything being looked into in the USA?
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On January 25 2012 11:09 Deathmanbob wrote:
This seems like one of those "to good to be true" things. If it really can do all that i would love to see a serious investment in the USA. OP because you knew that research was being done in china do you know if there is anything being looked into in the USA?
So far the only people in the US pursuing this is a company called Flibe Energy started by Kirk Sorensen who is the man featured in both of the documentaries posted in the OP.
http://flibe-energy.com/
They apparently have some military contracts to develop small modular LFTRs because under the current nuclear regulatory environment in the US it is easier to get unorthodox reactor designs approved for military use than it is for civilian use.
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Yes but as the article points out the high price of Throium is currently because it is not used for much, and if we started to build alot of LFTRs the price could drop to 10$/ton very quickly. There is a discussion in the "LFTR in 5 Minutes" video about how the fuel costs are essentially zero because Thorium is so abundant and is always being mined in rare earth mining operations, so the first several dozen kilotons of Thorium are already extracted and ready. In fact there is a really interesting part of the movie discussing how it would give the US an advantage over China in the rare earths market because it would make rare earth mining in the US much more profitable if thorium wasnt subject to all the unecessary regulations in the US. Thorium is currently treated as radioactive rock in the US and must be stored in nuclear disposal vessels, making it prohibitively expensive to mine rare earths in the US, since they are always found with Thorium. Thorium is not radioactive. It has a half-life of 14 billion years, as old as the universe, making it one of the most stable elements on earth. You can hold it in your hand or keep it in your pocket, it will not harm you.
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EPT
