(The reasons keep piling up. A more updated 25 reasons are found here ).
Eleven reasons to switch to Thorium based Nuclear Power generation.
1. Cheap and unlimited raw material. There is enough Thorium around for many millennia, and not only that, it is a byproduct of mining heavy metals and rare earth metals The price is the cost of refining it, about $40/Kg. 
2. 0.01% waste products compared to a Uranium fast breeder. The Thorium process has a much higher efficiency in fission than the Uranium process. See the figure below. 
Note the Plutonium in the Thorium cycle is Pu-238, which is in high demand. 
3. Radioactive waste lasts max 300 years instead of a million years. Initially a Thorium reactor produces as much radioactivity as other nuclear reactors, since that is what generates the heat by converting mass to heat, but the decay products have a much shorter half-life. See the figure below.
4. Can deplete some of the existing radioactive waste and nuclear weapons stockpiles. Thorenco LLC is developing a special reactor to purify spent nuclear fuel. This thorium converter reactor is designed to transmute and to “fission away” the heavy transuranic metals, the “nuclear waste” that the world’s fleet of 441+ light water reactors produce in spent fuel. This waste is about 4-5% of the volume of the fuel rods. It is composed of neptunium, plutonium, americium and curium. These transuranic elements are radiotoxic for very long periods of time. Thorenco’s technology fissions the plutonium and irradiates the transuranics causing the heavy metal elements to fission or to become lighter elements with much shorter decay periods. The thorium fuel cycle provides the neutrons as does the reactor grade plutonium. Nuclear power becomes more sustainable because the volume of the spent fuel from the uranium plutonium cycle is reduced by up to 95%. More importantly, the storage time for the residue from the recycled thorium fuel is materially reduced. This will have to be stored for less than 1% of the time needed for the storage of the untreated transuranics.
5. Produces Plutonium-238 needed for space exploration. WASHINGTON — The U.S. Senate gave final passage to an energy and water spending bill Oct. 15 2009 that denies President Barack Obama’s request for $30 million for the Department of Energy to restart production of plutonium-238 (pu-238) for NASA deep space missions. The House of Representatives originally approved $10 million of Obama’s pu-238 request for next year, but ultimately adopted the Senate’s position before voting Oct. 1 to approve the conference report on the 2010 Energy-Water Appropriations bill (H.R. 3183). The bill now heads to Obama, who is expected to sign it. NASA relies on pu-238 to power long-lasting spacecraft batteries that transform heat into electricity. With foreign and domestic supplies dwindling, NASA officials are worried the shortage will prevent the agency from sending spacecraft to the outer planets and other destinations where sunlight is scarce. Thorium reactors produce PU-238 as a “free” byproduct.
6. Does not produce Plutonium239 and higher used in nuclear bombs. The higher Plutonium isotopes are about as nasty as they get, and need expensive protection against terror attacks, and need to be stored for a very long time.
7. Produces isotopes that helps cure certain cancers. For decades, medical researchers have sought treatments for cancer. Now, Alpha Particle Immunotherapy offers a promising treatment for many forms of cancer, and perhaps a cure. Unfortunately, the most promising alpha-emitting medical isotopes, actinium-225 and its daughter, bismuth-213, are not available in sufficient quantity to support current research, much less therapeutic use. In fact, there are only three sources in the world that largely “milk” these isotopes from less than 2 grams of thorium source material. Additional supplies were not forthcoming. Fortunately, scientists and engineers at Idaho National Laboratory identified 40-year-old reactor fuel stored at the lab as a substantial untapped resource and developed Medical Actinium for Therapeutic Treatment, or MATT, which consists of two innovative processes (MATT-CAR and MATT-BAR) to recover this valuable medical isotope.
8. Earthquake safe. Thorium reactors have a very simple and compact design where gravity is the only thing needed to stop the nuclear reaction. Conventional Nuclear reactors depend on external power to shut down after a SCRAM, where poison rods fall down to halt the reaction. The next figure shows the concept of a Thorium reactor.
The idea is to empty the fissile U-233 core through gravity alone. Since the fuel is already molten, it can run out like pig-iron into cooling heat exchangers with water supplied thru gravity alone. 
As we can see the reactor hardened structure is compact, and can be completely earthquake and tsunami proof. What can be sheared off are the steam pipes and external power, but the shutdown can complete without additional power.
9. No risk for a meltdown, the fuel is already molten. The fuel in a Thorium reactor is U-233 in the form of UraniumFluoride (UF4) salt that also contains Lithium and Beryllium, in its molten form it has a very low vapor pressure. The salt flows easily through the heat exchangers and the separators. The salt is very toxic, but it is completely sealed.
10. Very high negative temperature coefficient leading to a safe control. This is another beauty of the molten salt design. The temperature coefficient is highly negative, leading to a safe design with simple and consistent feedback. What does that mean? It means that if temperature in the core rises, the efficiency of the reaction goes down, leading to less heat generated. There is no risk for a thermal runaway. In contrast, Chernobyl used graphite moderated Uranium , and it suffered a thermal runaway as the operators bypassed three safety circuits trying to capture the last remaining power during a normal shut-down. The reactor splat, the graphite caught fire and the rest is history. Five days later two nuclear installations in Sweden shut down their reactors due to excessive radiation, but it took a while before they could figure out what had happened. First then did the Soviets confess there had been an accident.
11. Atmospheric pressure operating conditions, no risk for explosions. Materials subjected to high radiation tend to get brittle or soften up. Thorium reactors operate under atmospheric conditions so the choice of materials that can withstand both high temperatures and high radiation is much greater, leading to a superior and less expensive design. There is no high pressure gas buildup and the separation stage can be greatly simplified.
Many of the pictures are from a slide presentation given by David Archibald in Melbourne Feb 5 2011. He posted it “for the benefit of all” which I have interpreted as waving the copyright of the pictures
Next installment: Eleven more reasons for Thorium https://lenbilen.com/2012/02/15/eleven-more-reasons-to-switch-to-thorium-as-nuclear-fuel/
Len Bilén's blog, a blog about faith, politics and the environment. 
You are comparing to heavy water fast breeders. Can you educate me on the differences with thorium reactors the newer light water reactors more common in France? thank you and great post.
Heavy water is DeuteriumOxide. It is like normal water except it allows neutrons to roam around freely without getting absorbed. You may recall the story of the “Heroes of Telemark” where Norwegian Resistance fighters sank a ferry containing a railroad car filled with heavy water thus derailing the German nuclear program for the rest of the war.Heavy water costs about $2000/gallon, so it is difficult to make reactors profitable with heavy water as a moderator. Its biggest advantage is that it can produce power and plotunium directly from narural Uranium without enrichment. Other than cost it is the easiest and safest way thechnologically to produce Nuclear Power.
Light water reeactors use enriched Uranium.
Thorium is FERTILE not FISSILE.
So how do you get the ball rolling?
The USSR and USA spent serious money on thorium molten salt reactors generations ago.
They were complete busts.
ANY design that uses fluorine in proximity to fission reactions — like the above — generates ‘hot fluorine’ nuclei which are destructive beyond all others.
No materials can be made that can withstand it. The afore mentioned countries spent most of their monies on just this one issue.
——
Thusly, thorium cycle reactors are ALWAYS on the cusp of promise, a technical tease that fools the non-engineer.
There are other astounding designs that float around the Web for ultra performance internal combustion engines.
They too founder on materials science: it’s impossible to build working prototypes because nothing can be found that can take the heat, pressure or torque said design requires.
And then, there’s the Stirling engine. It actually works. But, it turns out to be brutally difficult to make a practical machine with ordinary materials and ordinary techniques that has even slightly decent performance.
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The other crippling problem with thorium cycle technology: it produces U-233 in a form and way that is ‘easy’ to separate. ( All things being relative. )
That’s VERY troubling because U-233 is the single best nuclear explosive yet known.
It’s the quickest way to the atomic bomb — by far. No matter what scheme the above fellows create; ill minded fellows can wrap it with additional converter blankets of thorium — which would then be continuously processed to extract quantitatively pure U-233.
The fact that such a beast might only create grams per day is cold comfort: pure U-233 needs a trivial fraction of Little Boy’s charge — and absolutely none of Fat Man’s hyper-compression.
So thorium cycle technology is too dangerous to solve. It’s a blessing that all attempts break down.
Thank you for your comment. Let us take the points one by one.
Thorium is fertile. You are absolutely right. Thorium by itself is about as radioactive as bananas.
India is right now starting a heavy water moderated thorium based thermal breeder reactor with a plutonium spark plug to get the process going. We are having a large stockpile of U-233 at Oak Ridge and could have sold them some of it, but that was not to be.
We did indeed spend serious money on salt moderated reactors.
We spent about a hundred times more money on fast breeder uranium reactor technology.
Both were canceled after the Three Mile Island nuclear accident. After that we took a 35 year hiatus from any new serious nuclear power research.
The decision to cancel Thorium reactor technology was strictly political, not technical.
The Shippingport commercial Thorium reactor was a technical success, but since it was a research type reactor, the economy was not there to continue to have just one reactor of that type in the nation it was canceled after the Three Mile Island Accident.
Under heavy radiation all materials known to man tend to get mushy. Molten salt reactors have an advantage since they work under atmospheric pressure which greatly reduces fatigue problems.
And then there was the Chernobyl Catastrophe. The carbon moderated reactors have a problem with going prompt critical in the case of a failure to shut down properly. To gain the last bit of power out of a scheduled shutdown the clever operators had disabled the automatic scramming of the safety rods that poison the process promptly. We are still paying for that.
The last point about the easy separation of U-233 from Thorium-232 is interesting. The cat is already out of the bag. The U-233 retrieved from a breeder reactor is never turned pure on location but always mixed with Thorium in sufficient ratio to render it useless for terrorists without sophisticated reprocessing capabilities. It will never be anywhere nearly as troublesome as all the spent nuclear rods we stockpile everywhere since we do not have a functioning policy for reprocessing and storage.
The politics of re-processing are crazed with emotion.
In a perfect world we’d ship our stuff to the Atacama Desert in northern Chile.
We don’t live there, nor does much else.
It sits astride the world’s largest subduction zones — so injecting waste into the mantle is an option for the future.
It’s so isolated that perimeter security would be a breeze.
It’d permit deliveries by ship from all points of the compass.
It’s also fault free. It’s a wedge between mega faults that’s so stable that the Andes can rise to the heavens while it just ‘floats’ there – -between heaven and the abyss.
U-233 worries = Iran and other nation-states. The idea that wacko-terrorists are EVER going to have the moxie to work with and around radioactive materials — without killing themselves and without leaving ‘breadcrumbs’ all over the place — is absurd. So naturally, the various state organs of security constantly run the idea up the flag pole so that their powers are ever expanded.
I you pay someone to find problems — boy will he ever.
Reprocessing atomic waste with advanced robotics would yield astounding economic benefits.
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I’ve long advocated mass production of atomic reactors – -in the manner and style of large commercial aircraft.
Further, that these reactors should be EXCLUSIVELY mounted inside floating ‘keeps’ ( as in a castle’s keep ) which can be floated around the globe.
This bucket design would have the reactors ALWAYS below sea level. In extremis, the ocean would bleed off heat.
By staying moderately off-shore, power connections are sweet and easy. ( High Voltage Direct Current, always )
By using deep water as coolant you have the best Carnot efficiency.
At the end of life the entire contraption can be scrapped — with contaminated elements re-floated and dropped off into a subducting abyss. Plate tectonics would suck the beast into the mantle.
The nature of these mega-buckets would permit super scale reactors and power generation. Their security would be easy with the coastal ocean as a moat — and heavy weapons, castle style, to ward off any Bond villains.
Earthquakes and tsunamis would be withstood with aplomb: too far out to feel a tsunami – they’d sweep on past to the coast and the bucket would sit on unfaulted ground – in a semi-floating manner. ( Think of a ship deliberately beached in thirty meters of water that’s half empty, half laden. )
These bucket-complexes could be sited globally – -with the asset owned by America/ Japan/ etc. — just selling block power contractually. This way nations like Nigeria could power up on the cheap.
Naturally, these devices would be built in lower cost areas – -avoiding the difficulties of on site construction.
The scale of the enterprise would be so vast that sub-assemblies would come from every talented nation on earth.
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But there’s another option: hydro-power from the Andes – -particularly from the eastern face in Peru.
The Amazon acts as a solar collector. The energy is concentrated as snow and rain upon the Andes.
There is enough hydro-potential to power the ENTIRE planet at current levels on those slopes.
Which means that in the out years mankind can shift over to a hydropowered society — using various intermediary forms.
As you might imagine, such a path would upset the oil cartel.
I realize that it’s not very high tech. But it would scale large — keeping a lot of men employed.
It does have its limits: if the Sun winks out, if the Andes erode, if plate tectonics freeze… it won’t work.
Until then, it has some promise.
The last point on hydroelectric power in the Andes, I do not get anywhere nearly the power you seem to believe is there. Remember the only energy left to harvest is the potential energy from the mountains down to about 300’ elevation. The world production of electricity was about 12000 TeraWh/year in 1997. The economically feasible potential from South America is another 1600 TeraWh/year. In fact the total amount worldwide of yet to be exploitable hydroelectric power is about 8000 TWh/year. (Tera is 1,000,000,000,000)
The surveyor’s imagination of what hydro-potential is warped by their belief that containment dams the likes of Grand Coulee are the required method.
So they throw away high elevation flows.
Instead, calculate the square miles of solar collection in the western Amazon…
Then take a gander at the typical altitude of precipitation on the slopes.
Very unlike temperate climates the Amazon lays down HEAVY rains upon those slopes year-round.
It’s simply an area that gets no respect. The number of active dams in the area is zero.
The second largest dam in the world, Itaipu, is built like Grand Coulee. Meaning that it’s a ‘low-head’ dam. ( All things being relative. )
The hydo-potential of the Andes requires Swiss style very-high head designs.
It also requires mass production in the first world and remote delivery.
The ENTIRE hydro-power industry is stuck upon reactionary designs ( love that pun ) that matured generations ago. EVERYTHING is presumed to be big.
Hence, non-recognition of the ultimate power of the Andes watershed.
And, then, unlike PV, hydro-power runs at night, too.
As awesome as the statistics are, I can never see a day when the planet will use only the Andes.
Instead, I see a time when a blend of nuclear, hydro, and PV — with fossil fuel topping systems in a mature system.
I take issue with your assertion that everybody is stuck on the grand dam models. Granted, politicians are stuck on many things that do not have much technical merit. However lots of people are drooling about having a peak power processing plant that buys power at 3c/kWh and resells it at 30. All they need is a 1000 feet mountain with a lake on top. Unfortunately they are located in mountain regions where nobody lives. The profit goes up in transmission losses both ways. And it is almost impossible to build long transmission lines anymore. The high altitude drop turbines were used in Rjukan in Norway in the 1920’s.
You are right there is a lot of potential hydropower available in the third world. The Andes region is one. The other is the power available from the Kongo River. They do not even have to build a dam, the erelevation is already there. Unfortunately since the colonizers left Africa, what little infrastructure was there is being destroyed.
The Chinese have no qualms. They have built the world’s largest dam, the Three Gorges Dam in the Yangtze river. Unfortunately it is in a very active earthquake area, so, when it goes millions of people will get wiped out.
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