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Are Thorium Reactors in our Future?

With such a worldwide focus on energy that is NOT based on fossil fuels, it’s no surprise that breakthroughs in solar, wind, tidal, geothermal, hamster, and on and on seem to dominate the energy news. Most recently another source of energy seems to be having a resurgence, namely using thorium as a fuel source in nuclear reactors instead of uranium.

They’re calling it the nuclear fuel that will last for millenia, produce little waste, and can’t be proliferated into bombs.

Kirk Sorensen, a former NASA rocket engineer and now chief nuclear technologist at Teledyne Brown Engineering said:

“Once you start looking more closely, it blows your mind away. You can run civilization on thorium for hundreds of thousands of years, and it’s essentially free. You don’t have to deal with uranium cartels,”

So what’s the deal here?

Thorium, named after one of the coolest gods, Thor, is found on the periodic table near plutonium and Uranium but it’s only slightly radioactive, you could even carry in your pocket without much worry.

The main idea that many scientists are supporting including Nobel laureate Carlo Rubbia of CERN is the creation of reactors that use a thorium fuel cycle instead of a uranium based one.
In a nutshell, both these types of fuel can be used to create sustained nuclear reactions that reactors need to ultimately make electricity to charge all our iphones

What the difference then? What are the advantages of using thorium-based reactors

For one, thorium is much more abundant in earth’s crust than uranium.  Estimates put 3 to 4 times more thorium than uranium in the world. Miners actually consider it a nuisance. Since one ton of Thorium produces as much energy as 200 tons of uranium, it could be quite a long time before we run out.

Conversion of thorium into a fissile material is more efficient as well. It has a better Neutron Economy which means that less neutrons are created uselessly (the term also refers to the overall efficiency of the reactor design)

Thorium also simply has better chemical and physical properties compared to uranium. Examples include a higher melting point, less thermal expansion, and overall greater stability. All of these characteristics improve reactor performance, lower their cost and make them simpler.

One of the biggest advantages is that some Thorium reactors are naturally resistant to proliferation. In other words it would not be easy to extract uranium or plutonium from this process to make weapons.
Some science writers seem to oversell this point. For example, Takahashi from the Huffington Post on Jan 5 wrote:

“There is no terrorism potential for the thorium cycle.”

I was skeptical of this primarily because…well it was on the HuffPo site.

There’s lots of conflicting talk about this specific advantage from sources all over the map.
My take is that if you’re using a thorium reactor designed to be proliferation resistant like a liquid fluoride thorium reactor, or LFTR then it would be very hard to make bombs although it’s probably not impossible.

If however this specific design was changed then you could more than likely still have a thorium reactor but it could also fairly easily produce byproducts for weapons.

There seems to be little question that proliferation would be reduced worldwide if all reactors were LFTRs but a nation determined to make plutonium is going to do it one way or the other. There are many pathways to making fissile material and LFTRs are no panacea.

It may sound like Thorium based fuel is a new idea but  it was shown to work in tests more than 60 years ago. It seems that one of the deciding factors against it was the fact that the United States needed an easy way to make plutonium to make bombs to keep up with the Russians. Another pivotal time in history occurred during the oil embargo of the 70s. Desperate for an alternative source of energy, the US fast-tracked the approval of a plethora of uranium reactors, essentially killing any thorium reactor research that was still going on. Uranium-fueled reactors never looked back. Thorium reactors became a footnote in the history of nuclear energy.

That footnote is now getting de-footnoted it appears.

The appeal is obvious, right?
More than ever, we desperately need carbon-free electricity and nuclear energy is entering another renaissance now because of that fact….This new thorium design appears to make nuclear reactors even more compelling.

So compelling that nuclear industries around the world are taking a very serious look at this stuff. France which gets 75 percent of its electricy from nuclear power is trying to make existing thorium designs more efficient. India and China are probably the biggest players with obvious interests in this technology.

My bottom line on this is that it deserves more attention for many reasons like cost, size, complexity, efficiency etc but it is not a panacea for the spread of nukes like many are advocating.

P.S. Just found this cool looking thorium-fuel base concept car.

Designer Loren Kulesus apparently claims that this car can go a century without engine maintenance or refueling.

I am of course skeptical.

9 comments to Are Thorium Reactors in our Future?

  • You’re spot on. The whole Nuclear proliferation thing seems to be a giant red herring. The world’s biggest polluters are all nuclear powers anyway. If only the current nuclear powers (which by my rough estimate make up at least half the world’s population) changed their fossil-fuel burning power stations for thorium reactors then the environmental impact would be huge. Surely that’s reason enough to look seriously at the technology.

  • [...] This post was mentioned on Twitter by SkepticsGuide, Ryan Gigliotti and michael ellerby, Pete Manning. Pete Manning said: How could we have overlooked this? RT @SkepticsGuide: Are Thorium Reactors in our Future?: [...]

  • I’m with Jay, this just raises a lot of red flags. That being said, I really hope this does turn out to be as awesome as it sounds. We just need to be careful =) I’m pretty sure I’ve seen this sci fi story line before, amazing new fuel source discovered but abandoned in the 60s, seems like the first half of something we are going to need the Dr to get us out of. JK

  • “There’s lots of conflicting talk about this specific advantage from sources all over the map.
    My take is that if you’re using a thorium reactor designed to be proliferation resistant like a liquid fluoride thorium reactor, or LFTR then it would be very hard to make bombs although it’s probably not impossible.”

    The proliferation question is a tricky one. A LFTR, in theory, produces excess Uranium at a known rate at full power (about 10% core mass per year). The mix is U-233 with traces of U-232 from the odd (n,2n) reaction.

    The U-232, and specifically the hard gamma emitters in its daughter products are what are considered the primary deterrents to proliferation resistance, with easy accounting a close second.

    On the other hand, I’ve never seen predictions of U-232 production rates in a LFTR reactor, nor measurements from the MSR prototype on which it’s based – but that’s just probably a lack of clearance on my end.

    Still, that means I have no idea how credible the primary claim of resistance is, since I have no idea how prevalent the U-232 contamination is.

    That said, the main argument against reprocessing is proliferation issues with plutonium – but light water reactors have similar contamination in their plutonium.

    In a thermal spectrum with high burnup, like in an LWR, you only get about half 239-Pu. Of the rest, 240-Pu has a high spontaneous fission rate, making the 23% or so present in reactor grade plutonium anathema to building a stable bomb. 241-Pu – another 24% – has a decay chain with very short-lived stuff, meaning high heat and gamma production, not to mention other spontaneously fissioning actinides.

    The spontaneous fission and decay properties of spent fuel plutonium similarly make enrichment to the 80% 239 needed to make a useful weapon something only governments can pull off – at which point you might ask yourself, “Why aren’t we just enriching natural uranium again?”

    The United States’ solution to this problem is to have reactors designed with a flux shunt: you have a shunt near the core through which slugs of material can be passed in and out of the core’s neutron flux. Passing depleted uranium slugs through this shunt for 1-2 months of burnup yields small amounts of nearly pure 239-Pu that can be chemically separated from the 238-U.

    Preventing this in any reactor design is relatively easy: deny open space anywhere near the core flux. I wouldn’t be surprised if that’s part of the NRC’s design requirements.

    I should mention that while Kirk is very quick to say “We’ve built one”, that’s not entirely accurate. We’ve built a 233UF4-fueled molten salt reactor with burnup and neutron flux characteristics that would, within a thorium blanket, breed 233U faster than it burned it. That is to say, the principle has been proven, but the practice has yet to be completed.

    Mind, I’m a programmer, not a scientist of any flavor. So anything I say, take with a pound of salt – preferably, LiF/BeF2.

  • rstubbs1

    For more information about Thorium reactors, see, and It really is as good as it sounds, but it needs funding to develop the technology to commercial reality, and time to get through the slow and bureaucratic regulation process. The more popular support the technology has, the faster the politicians will (hopefully) move to make it a reality!

  • Yeah, I can’t help but think that if this was such a Good Thing™ that it wouldn’t have already been done long ago. I’m guessing the main issue, aside from the general public fear of anything nuclear or radioactive, is one of economic feasibility.

    Thorium-232, the isotope that would be used in a reactor, has a half-life of 14 billion years. What that means is that it is emitting radiation energy at a very slow rate–thus its ability to be carried around in your pocket. I wonder though if this could be a disadvantage; low energy emission would seem to mean that either you’d need a whole lot of the stuff, or that energy output wouldn’t be all that great. It may have 200 times the energy of uranium, but if it takes 14 billion years to get half of it….

    Also I’m not sure where you got the picture at the top but Wikipedia says Thorium is silvery-white in color. Speaking of which, there are some pretty informative articles there. Try a Wiki search on “Thorium” and “Thorium fuel cycle”. The latter article lists several disadvantages of Thorium as a nuclear fuel, which I do not feel qualified enough to sum up here. There seem to be a few issues involving uranium though.

  • [...] I just ran across another great article about the same topic from The Skeptics Guide. Will Thorium Reactors be in our future? It also includes pictures of a thorium based concept [...]

  • [...] The future of nuclear energy could rest on the use of Thorium for fuel. Thorium is theoretically more energy efficient and less likely to produce materials which could be used in weapons. [...]

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