Thorium: A safer alternative for nuclear power generation?


May 26, 2011

Thorium could provide a cleaner and more abundant alternative to uranium (Photo: Three Mile Island Nuclear Power Plant/ Lyndi & Jason via Flickr)

Thorium could provide a cleaner and more abundant alternative to uranium (Photo: Three Mile Island Nuclear Power Plant/ Lyndi & Jason via Flickr)

The world's growing need for energy, the limits of our supply of fossil fuels and concern about the effects of carbon emissions on the environment have all prompted interest in the increased use of nuclear power. Yet the very word "nuclear" carries with it an association of fear. People are concerned about the waste produced by reactors, the possibility of catastrophic accidents as highlighted by recent events in Japan and the link between nuclear power and nuclear weapons. Yet what if there existed a means of nuclear power generation with which these risks were drastically reduced?

The answer could be thorium - an element occurring as a silvery metal that's more abundant, cleaner and can produce more bang-per-buck in energy terms than uranium. So how does thorium differ from uranium and plutonium, and why isn't it being used? First, a quick run-down on how nuclear energy works.

What is nuclear power?

The word "nuclear" refers to the nucleus, or dense center of the atom. In a nuclear power reactor, these nuclei are split into smaller parts through a process known as fission. A sub-atomic particle known as a neutron strikes the nucleus of an atom of suitable fuel (particular isotopes of the heavy elements uranium and plutonium) breaking it into its component parts. Each fission results in the release of energy in the form of electromagnetic radiation and kinetic energy in the fragments of the split nucleus. This effect is twofold; the release of energy will produce heat, and the release of neutrons, which can in turn fission other atoms.

In material that has typically been employed as nuclear fuel, this reaction occurs in a "chain reaction" and is self-sustaining. When this is occurring, the reactor can be said to be"'critical". In a fission weapon, a mass of plutonium or uranium in excess of critical is assembled very quickly, with a flood of neutrons from a device known as an "initiator". The release of energy is extremely rapid and results in a massive explosion.

In a nuclear power reactor, the reaction is far slower and more controlled - the heat produced can be harnessed to boil water to spin turbines for the generation of electricity and this has been in practice for decades. The use of nuclear reactors for power generation began on 27 June 1954 at the Obninsk power plant in the former Soviet Union and has continued in numerous countries to this day.

There are of course, some significant problems with nuclear power. Fission reactions will always result in the production of radioactive waste products which require secure storage and pose a health risk to humans and the environment. There is the possibility that the operators may lose control of the fission chain reaction resulting in an accidental release of this material (often referred to as a "meltdown"). There's also the concern that reactors may also be used for the production of material suitable for nuclear weapons.

Modern nuclear reactors

The two main types of reactors used for commercial power generation are the pressurized water reactor (PBR) and the boiling water reactor (BWR), which both typically make use of uranium in the form of uranium oxide fuel rods. The criticality of the reactor is managed by control rods, which when inserted absorb neutrons that would otherwise cause the chain reaction to continue. The reactor can be shut down, or "scrammed", by the rapid insertion of these control rods. However, this is a manual process and there is a possibility of an error occurring.

Criticality, fertility and the potential of thorium

The element thorium, named after the Norse god of thunder, may provide a safer alternative as a fuel. The key difference between thorium and other nuclear fuels is that it cannot sustain a chain reaction on its own. Fissile fuels like uranium and plutonium are able to sustain a chain-reaction, yet fission can also be achieved in material like thorium that is not fissile but fertile - i.e. it can produce fissile material, if neutrons are provided from an outside source.

Thorium is estimated to be three to four times more plentiful than uranium in the Earth's crust and has the advantage of being found in nature in the one isotope, which makes it suitable as a nuclear fuel as it need not be enriched to separate the right isotope. For convenience, thorium fuel can be used in the form of a liquid molten salt mixture.

Accelerator Driven System

Fission occurs in thorium when atoms absorb a neutron to become a heavier isotope and quickly decay into an isotope of the element protactinium and then an isotope of uranium, which is fissioned when struck by an additional neutron. The number of neutrons produced is not sufficient for a self-sustained chain reaction.

A particle accelerator could be used to provide the necessary neutrons for fission to occur in thorium and a nuclear reactor making use of such an outside neutron source would be known as an 'accelerator driven system' (ADS).

The notion of the ADS is credited to Carlo Rubbia of the European Organisation for Nuclear Research (CERN) joint winner of the 1984 Nobel Prize for Physics. The ADS would likely be far smaller than other reactors and if the accelerator were to be turned off, the nuclear reaction would cease, although it should be noted that even in a reactor which is not critical, the heat from the decay of materials can be significant and cooling is required.

In a thorium reactor, quantities of other fuels could be included, without the fuel being capable of sustaining a chain reaction, and thus the reactor could be used to provide energy from disposing of material such as plutonium from disassembled nuclear weapons. It's also possible to ensure that the reactors are designed in such a way that it is not possible to extract fissile material, which can be used to manufacture nuclear weapons.

Though all nuclear reactors will produce waste products, a reactor fulled by thorium will produce far less long-lived waste products than one fueled by uranium or plutonium, with waste decaying to the same level of radioactivity as coal ashes after 500 years.

Thorium also produces more energy from the same amount of material compared to uranium.

"Two hundred tonnes of uranium can give you the same amount of energy you can get from one tonne of thorium," Rubbia told the BBC News in a recent interview.

Towards a thorium reactor

Though several reactors have made use of thorium for experimental purposes, a thorium power reactor is not as yet a reality. Countries like Russia, India and China are looking at the use of thorium and such a reactor may one day soon be a viable energy source.

So why has it taken so long for thorium to hit the nuclear power agenda? The key reason seems to be that because it can't be used to make a nuclear bomb, it was largely ignored during the Manhattan project and in the development of nuclear power stations that followed.


This ain\'t new, the idea has been around for some time... but it\'s time someone build one using Thorium rather than Uranium...

Windmaster Hiroaki

Google sponsored some lectures on LIFTR (LIquid Fluoride Thorium Reactor) technology a few years back. You can find them on YouTube if you do a search. Some very good (and technical) information there. Almost all upside. Almost no downside. (Nothing is perfect) Significantly greener than oil, gas or the current state of nuclear. If you take into account the massive amount of pollution created by the production of photo-voltaic it\'s even greener than that and doesn\'t consume thousands of acres of delicate desert land. Have a look.


What\'s the environmental impact of the mining process like compared to uranium? And where are the main deposits of the stuff located, internationally speaking? (as in, what countries would stand to gain/lose from a Thorium reactor revolution mining wise).

Earl Leonard

A nuke dummy I almost fell for the hook. The grid is the issue. Individual power no grid no stock holders, no officers to drive the cost of energy up so the sale of planes, boats and fast cars can continue unabated. The Grid comes down, get ready with individual power sources, Red Dawn is the model, and the Grid makes us vulnerable to Canadians looking for a beach. The fossil fuel revolution comes to an end before we all suffocate. Nuke ends before we cook ourselves to death, Fukushima is a four letter for GE.

The Agents of the Crystalline Matrix

Patrick McGean

Get a grip guys. This is just old hogwash: In 2008 a report from the Norwegian Radiation Protection Authority (NRPA) revealed that thorium-based nuclear energy plants - once vaunted as a clean alternative type of nuclear energy - have the same negative environmental consequences as their uranium-based cousins do. The NRPA report dealt with the environmental consequences of potential thorium related industry in Norway. The report takes on various aspects of the thorium fuel cycle from mining and extraction, fuel production, reactor operation and waste handling. The report concludes that the environmental consequences of using thorium-based nuclear power will result in the same problems the world faces today with uranium bases reactors. "The NRPA invalidated that thorium is kind nuclear power, as many have earlier asserted," said Nils Bohmer, nuclear physicist with Bellona, a Norwegian based environmental organization. "Using thorium leads to highly radioactive nuclear waste and the risk of accidents will always be present." According to the NRPA, thorium-based nuclear energy, uncontrolled chain reactions and, in the worst case, meltdowns can occur. The NRPA also asserts that thorium-based nuclear energy will produce long-lasting radioactive waste that will demand the same handling as highly radioactive waste from current nuclear reactors. The NRPA report also points out that it is impossible to give a full value oversight of all potential environenmental consequences of thorium-based nuclear energy. The report shows that each form of thorium extraction, whether by open-pit mining or underground mining, will lead to negative burdens on the environment. Extraction will produce radioactive waste in the form of slag heaps that can lead to an escalation of radiation for humans and the environment, and the spread of radioactivity. Earlier, many had asserted that thorium technology cannot be used for weapons purposes. Even though this would be more difficult than with current technology, the NRPA report shows that this will continue to be possible. In the 1950s, the United States accomplished its first test explosion with uranium 233, which is the material thorium-based energy production produces. Additionally, highly enriched or plutonium is required as an additive to thorium to produce a chain reaction. These are materials that can be abused for weapons grade purposes.


Go,Thor! HAMMER DOWN! {^,^}


According to the USGS, USA, Australia and India have particularly large reserves of thorium, with India possessing the largest quantity.

Racqia Dvorak

Thorium is highly abundant and easily attainable. It runs on a low pressure system, so much safer than present day high pressure Nuclear reactors. It\'s also nearly 100% efficient. Here are some figures from Kirk Sorenson\'s Google presentation:

6600 tonnes of thorium (500 quads) is equal to one of the following in the list below:

5.3 billion tonnes of coal (128 quads) 31.1 billion barrels of oil (180 quads) 2.92 trillion m3 of natural gas (105 quads) 65,000 tonnes of uranium ore (24 quads)

more figures.

6 kg of thorium metal in a liquid-fluoride reactor has the energy equivalent (66,000 MWhr electrical) of:

230 train cars (25,000 MT) of bituminous coal or, 600 train cars (66,000 MT) of brown coal or, 440 million cubic feet of natural gas (15% of a 125,000 cubic meter LNG tanker), or, 300 kg of enriched (3%) uranium in a pressurized water reactor.

Kirk Sorenson is an expert on the matter, check his site for how things are developing:

Fabrizio Pilato

Um the grid does need a serious upgrade. but the grid is good silly rabbit. If you live on a farm and don\'t have a family sure you can have some wind mills, most people live in burbs or cities.. What then? No one wants solar panels even with subsidies they are 30-40 cents per kwh, and then you have to charge something to get through the night.. then it gets to a $1 per kwh. No thanks I think we will keep the grid and just build more nuclear plants.

Michael Mantion

Thorium is very abundant. but then again so is uranium, especially all the spent fuel that could be reprocessed.

Michael Mantion

One of the promising things about Thorium reactors is that they can be built significantly smaller than current Uranium based reactors. It\'s possible that a town could purchase and install their own reactor rather than relying on grid power. There even is a proposal for a portable reactor designed for remote site power and heat generation.


About 3 years back a thorium powered reactor was being fitted into a ship to test the feasibility of the system. France maintains a good stockpile of Thorium - about the only country to do so. But you must get your perspective right, for virtually all countries with nuclear reactors, it\'s the power generation that is the by-product - the ultimate product is what we\'ve cleverly been taught to call \"waste material\" - weapons grade fissile material.


In addition to comments made by Eletruk;

Not only would the decentralization of the grid be beneficial to the reliability of service since more and smaller plants would cover the energy needs not only better, less energy would be wasted over long distance transport, and reducing single points of failure. And let\'s not forget in times of disaster how slim chances of it might be, that would be the moment when you want to be ensured of energy.

Also Windmills are very green for many but they look very grey, tall and ugly to me when I pass them by, in otherwise beautiful landscapes, the same goes for the pylons wasting the skyline.


John Kepers

\"It\'s also possible to ensure that the reactors are designed in such a way that it is not possible to extract fissile material, which can be used to manufacture nuclear weapons.\" This is important, as apparently U-233 can be employed in a simple gun-type assembly weapon, easily built by a well-funded group. Also, is there a link to an english language version of this NRPA report?

Zeb Leonard

The debate on Nuclear power intensifies no sooner than there is a mishap and the recent japan disaster has perhaps been more intense consideering the magnitude of the destruction. Although nuclear power has been foremost in a few countries, the precautionary aspect seems to have been neglected. Suggestion on thorium is like experimenting with a new fuel without perhaps the knowledge on inherent destructive potential it may throw up later when we all start debating on. Although it is not too late, we need to pay greater attention to the nuclear generation with uranium and plutonium to minimise the impact.

Asoor Shyam

Kepers I might have to disagree with you. smaller plants are in general less efficient and more polluting. Electric travels very well over long distances must of the waste is close to the consumer. I agree much of the grid could use an upgrade, but wasting time, money and other resources on making many smaller plants really won\'t help. Sadly we import more electricity then we export. We do need to decrease our demand or increase our supply, but building power plants in Canada or even mexico is easier then making them in the US. We would be well served if the states had more control over power production. Also why do people keep bashing the appearance of wind mills. I think they look awesome. Driving through wind farms in so cal in Texas is nice. If they tried to generate the same power from solar cells you wouldn\'t see the ground at all, it would be a sea of silicon panels

Michael Mantion

Overall, an informative article, but there are a number of technical errors that are being propagated through several of the recent articles out there on thorium.

The major technical error is quote from Rubbia: \"Two hundred tonnes of uranium can give you the same amount of energy you can get from one tonne of thorium,\" This is absolutely not true and he is comparing the use of thorium in a full recycle system to that of our current-generation reactors with no recycle. If you fully recycle uranium, like he is assuming for thorium, they both will provide the same amount of energy (one tonne of thorium equals one tonne of uranium). It should also be pointed out that ADS can be used with uranium as well as thorium. The advantage that thorium will have is lower production of higher actinides.

Another error in the report is the statement: \"The reactor can be shut down, or \"scrammed\", by the rapid insertion of these control rods. However, this is a manual process and there is a possibility of an error occurring.\" Modern reactors can be scrammed manually, but also have automated scram systems and they do scram automatically based on particular set points on plant conditions.

Finally, this statement \"The key reason seems to be that because it [thorium] can\'t be used to make a nuclear bomb,\" is absolutely false. Thorium certainly can be converted to U-233, which is a fissile material, like U-235 or Pu-239. It is true that the products from civilian nuclear power systems, whether they are uranium based (producing Pu) or thorium based (producing U-233 with U-232) are not desirable.


We have learned so much about the amazing energy in the nucleus of heavy atoms and the best non-lethal use we can come up with is... Steam? Thorium would be a safer generator of steam, but the spent fuel is still toxic and hard to store safely. I would prefer more research dollars put into direct conversion of radiation to electricity. Out here in the west, there are several likely spots where generation of electricity might become as simple as drilling a hole and dropping in the proper receptive materials. I want to leave the bulk of reactive materials where it is.

Chris Chiller

I wouldn\'t worry excessively about the environmental consequences of mining thorium as fuel, since there\'s presently an overabundance of the stuff stockpiled.

Thorium is a waste product of rare earth element mining, so as long as we\'re already digging up ores to make magnets, there will be a \"free\" source of nuclear fuel.

Also, unlike uranium, there is only one naturally occurring isotope of thorium, so very little refining needs to be done, which means that there\'re relatively little environmental impact from that.

How safe thorium is in a reactor depends on which reactor design is used... some designs are basically meltdown-proof, and we can expect any new thorium power plants to use such designs... but it\'s also possible to use thorium as a fuel rod ingredient for use in reactors which were originally meant to run on uranium, in which case it\'s no safer than uranium.

Similarly, how clean the waste is depends on the reactor design... the most efficient designs produce a waste which is safe to landfill within five centuries, while putting thorium in a fuel rod to burn it in a reactor that was built for uranium use will result in a waste product that\'s just as long-lived as conventional nuclear waste.

Ben Goldberg

All this sounds great in theory. My concern is that if these types of reactors are built and become a source of power for our country, what will keep the prices of Thorium from escalating just like Oil?

Some country will end up being the owner of the most abundant supply of Thorium, and then of course we\'ll be subject to their pricing and supply demands. I think the absolute worse thing the US could do would be to adopt an energy source that merely puts us at the mercy of another country.

We need an energy resource that we control and can access right here at home. No...sorry I don\'t have the solution for that proposal, but you can look at this just like Oil.

If we do build Thorium reactors, then we become dependent upon whatever country ends up being the supplier. I really don\'t think we would be any better off.

Kerry Thomas

@ patrick... Please search LFTR before you make wild claims that \"it is the same as conventional nuclear\" Git a grip! The liquid fluoride THORium reactor IS the worlds hope for clean, rather cheap and definitely UNLIMITED energy! It has been proven and demonstrated and only needs a little bit more research to make it work indefinitely. Go molten salt reactors (because they don\'t meltdown when solar flares knock out the grid)! Please contact your reps today and tell them why!

Robert Bernal

@ben goldberg: Don\'t worry about any monopolies: thorium is widespread, and 4 times more common than Uranium . There is already enough stockpiled as a waste byproduct to last the whole world for a long time. For info about all this, see Kirk Sorensen, Thorium, on Youtube. For those fearful about Thorium radioactive waste, it sounds as though you are assuming its use as a substitute for Uranium in a Light Water Reactor; that is not at all what the LFTR does, rationally.

Shawn Disney

I would be wary of the NRPA report. Liquid Thorium Salt reactors don\'t make as much money for the present suppliers of nuclear fuels and reactors, so they will do whatever they can to attack the idea of liquid thorium salt. Stacking the deck with \"official reports\" is an old ruse. Add the opposition of the industry with that of the anti-nuclear left, and you have a formidable political force against what could well be the only way out of our present nuclear waste dilemma.

Far, far down the road, when Thorium starts getting scarce, we will surely have large scale synthetic photo-synthesis in place, or even fusion. Thorium is the bridge fuel on the road to photo synthesis.


I don\'t remember ever seeing any negative comments on thorium that were not dealing with solid fuel designs, mostly Dr. Rubbia and derivative variations on his solid-fuel reactors. And, yes, solid-...fuel thorium designs have all the same problems of any pressurized water reactor (PWR). Thorium in a molten salt reactor (TFMSR or LFTR) is a completely different conceptual paradigm. Much more info is available at [...] [...] and the Thorium Energy Alliance [..] [...], and click on the \"resources\" menu tab.


There is no perfect solution yet. Windmills and solar panels can not meet our energy needs, nor can you reasonably expect people to use significantly less energy. Coal fired plants and nuclear plants have obvious environmental concerns. And hydroelectric is limited since there are only so many waterfalls and rapids to tap and construction of dams can have massive environmental and human repercussions.

Is thorium the perfect solution? No. Will it ever be our only source of power replacing all others? No. Once mature will this technologies benefits outweigh its drawbacks when compared to other realistic alternatives? I think so, potentially by a significant margin.

Samantha Renault

I\'m taking time off with my obsession with hand counting our votes in the precinct immediately after the polls close, but here goes..

The NRPA report gives us an all things being equal scenario. Given the 400 yr half life of liquid thorium against the 10K half life of present waste, Thorium wins the argument. Overheating automatically melts salt plugs in the Thorium reactor and scams the reactor. No outside controls needed. Thorium wins that one. Present nuclear can be reprocessed, but that just extends the dangers. Present nuclear waste can be processed, but used in the Thorium reactor as its dangerously long half life is turned into electricity.

Finally, any talk of grid upgrades is an obvious smokescreen, given the scalability of safe Thorium.


@Dawg... Prefer to read the Norwegian Radiation Protection Authority (NRPA) report which \'Bellona\' (an environmental pressure group) refers to, myself. Seen the article you are quoting from on Bellona\'s web site, but they don\'t link to it either, which leaves any reader to rely on their own conclusions... and as I pointed out, they are hardly impartial, being an environmental pressure group.

I have to say I\'m also skeptical of any reports about Thorium safety coming out of Norway, because their country is completely dependent on their substantial natural oil and gas reserves. The International Monetary Fund IMF rates Norway as the second richest country in the world [1] based on nominal GDP per capita (USD), purely due to oil and gas production. Norway also has the 2nd largest sovereign wealth fund in the world, (larger than China\'s), and all of it is due to oil and gas production [2].

[1] World Economic Outlook Database-September 2011, International Monetary Fund.


Max Bone

@csbrudy RE: the salt plug melting and scramming the reactor, is it not true that even when a reactor is scrammed and is no longer critical, decay heat can still be very significant? Seems to be that Fukishima was a good example of this, control rods went in but still a great deal of heat....

Zeb Leonard

Managing demand for power is a much better solution than generating it.

The word need is incorrectly used in this context. Get basic facts like this wrong and you end up making bad desicions - such as building powerplants whose waste products have to be carefully and expensively managed for timescales beyond any pre-existing civilisation.

The idea of nuclear power will always remain desireably cool to techno geeks like myself, but completely idiotic for society to adopt until the entire system - from cradle to grave - is made intrinsically safe.

Just think about the consequences of another global flu pandemic - how long can the various infrastructure systems operate without proficient experts to maintain them, or decommision them when they fail?

Robbie Price

@Zeb, LTSRs run at about 1500 degrees F. This is so much cooler than current LWR that water is needed neither to produce steam nor cool the reactor. The salt itself drives the turbines. Should something go wrong, such as a turbine seizing up, the increasing heat of the liquid just melts salt plugs, which normally contain the solution. The best design would be spherical, so that should the reactor be moved out of place by a tornado, earthquake, tsunami or hurricane, it would melt one or more plugs no matter how it "landed", and automatically scram. The Oak Ridge reactor, which ran for some nine years, was regularly shut down by having the plugs melt. It should be known that the Federales have a large store of U233, and that the nuclear industry fought for millions in funding to get rid of it, because LTSR is the best alternative to their LWRs, and they are afraid of it. Cheaper, safer and easier to build, the LTSR can initially seeded with U233.... Then kept going by recycling all the nuclear waste we have sitting around in holding ponds. @Max, thanks for the background on the Norwegian report, especially the info on their petroleum reserves.


I'm learning a lot. Brown's Gas can neutralize nuclear waste. Any ideas on how that might influence choices of reactors? You can get more information on Brown's Gas under the Meltdown links at Scroll down to Brown's Gas and the press announcement video from 1993. And if it's not too off topic, how likely is the scenario by Major General Stubblebine, that a 6.2 earthquake or another tsunami, would take down reactor #4 exposing 1,315 fuel rods and the dangers of another 6,375 more stored within 50 yards with a total 11,641 at the sites. Is anyone aware of any mitigating factors that would keep Fukushima from starting a biblical level disaster? Thanks.

Don Winfield

I would like to have the source of the NRPA funding confirmed. Max Bone's comments on Norway's reliance on the oil and gas industries are perfectly valid and means that the NRPA's comments must be highly suspect. If the NRPA is also receiving funding from the conventional nuclear industry I think that that would prove that their 'findings' are totally biased and untrustworthy.

It is obvious from the original article and comments that Thorium is more plentiful and easier to convert to use for fuel than uranium. The USA is a major source of raw thorium, along with Australia and India, so the suggestion of the US being 'held to ransom' for supplies is a spurious one (I live in the UK). So it is more plentiful, easier to convert and more efficient in use - even without the suggestion that it is safer. So what is holding up it's use in prducing nuclear power? Obviously, the vested interests of the existing nuclear industry!!!


I would like to thank those of you here who have helped to debunk many of the negatives do the Thorium reactors. The single most important thing people fail to realize is the reactor mechanism using the molten salt is WAY different than the High Pressure systems in use today.

Dr. Weinberg who invented the currently used technology tried the best he could to dissuade us from continuing to use the inherently unsafe High Pressure systems and move towards the system he had running at Oak Ridge for quite a few years. As mentioned above, it was shut down every Friday (no one wanted to work weekends) and cranked up again on Mondays.

Many experts without a funnel ending in their bank accounts agree that this is the best option moving forward to put us where we all want to be.

A spent fuel that can be encapsulated and then be safe in only 500 years is leaps and bounds ahead of where we are today not including the fact as @csbrudy says we can use these reactors to recycle spent fuel from other Nuclear facilities.

Please, contact your representatives at every level and put a bug in their ears!

Dr. Veritas

to many times has the nuclear industry said this time its different ya its possible to make a thorium reactor that has waste that would be safe to make dinner plates with the risk of some type of accident still exists there is a alternative Google water car japan

now if you can run a car on water you can run a generator this is a form of over unity now what would happen if you took the exhaust ran it though a condenser and a stirling engine or used the water once taken apart from this supper effeincent electrolysis ran it though a fuel cell or if you combined it with an atmospheric water generator this make solar and wind rather pointless those who try to market stuff like this end up dead or framed with the murder of their partners so the change we need is nothing to do with rather or not we need the grid the grid needs to go no question and so does the corporate person hood status and a few other big changes

Tha Unameable
Post a Comment

Login with your Gizmag account:

Related Articles
Looking for something? Search our articles