Thorium: a future option for nuclear?

Nuclear reactors running on thorium are widely held to be inherently safer than the awful pressurized-water reactors we have today. So why don’t we have thorium reactors? A new TV documentary also available online answers the question quite well. Craig Morris sums up the evidence.

the Kalkar power plant in Germany

the German Kalkar power plant, which failed to go online (Photo by Raimond Spekking, edited, CC BY-SA 4.0, via Wikipedia Commons)

The documentary in French and German (but available with English subtitles) aired in October on the Franco-German TV station Arte. The film clearly calls for tremendous investments in thorium nuclear, with a prototype reactor costing “a billion euros.” Proponents of the idea quoted in the film put this amount into perspective: Goldman Sachs paid 16 billion dollars in bonuses in 2010 alone. The documentary thus is an ad for thorium and cleverly begins with one in order to appear more objective; a comic strip version of the late nuclear expert Alvin Weinberg tells viewers he is sick of ads and asks whether we are ready to take a deep dive into the technology.

The documentary’s sales pitch is convincing, and I do recommend the movie to anyone who wishes to know what thorium nuclear reactors are (or would be) and why we don’t have them. The benefits are clearly explained:

  • Radioactive waste would be reduced by around 80%, much of which would only have a half-life of seven years.
  • During operation, the reactors would probably be inherently safe. The problem with the reactors we currently have is that they need cooling even when they are shut down or break, as happened in Fukushima. When a thorium reactor cooled with molten salt has an emergency shutdown, the liquid salt can be dumped into a reservoir under the reactor, where it would quickly cool down enough to harden so that leaks would not even be a problem.

So why don’t we have such reactors? The reason given in the film is the one we also give in our book, Energy Democracy, in telling the history of nuclear in Germany. Basically, the first nuclear reactors were actually built to produce material for nuclear weapons. The nuclear power plants we have today were derived from this design. In fact, the one that blew up in Chernobyl was technically a military reactor repurposed for power production.

Once this reactor type had become the utility favorite, other competing designs were discouraged. Utilities and the government did not want potentially safer reactors to succeed, lest the public demand the immediate shutdown of the reactors already built, which have the worst possible design of all the options originally on the table.

The Germans also played around with thorium. Strangely, the documentary does not tell the story of Germany’s thorium reactor in Hamm from the 1980s, probably because it is not exactly the kind proposed (for instance, the German one used helium, not molten salt, for cooling). But Germany also had a reactor with sodium as the coolant in Kalkar.

The thorium reactor ran for just over a year and was closed because of rising costs (basically, it broke). The other was also closed based on cost, but it never had time to break. With the molten sodium flowing through the cooling system and the reactor ready to be loaded with fuel rods, the state government refused to give the go-ahead, and the plant operator eventually gave up because keeping the sodium heated up as a liquid was costing millions of deutsche marks every day.

Do either of these German examples provide any lessons?

The Chinese have also tried their hand at the kind of thorium reactor described in the movie, and they could not quite get the technology to work either. But the problems could be manageable; the reactor design does not pose any obstacles that might not be solved through trial and error. The big one – and the one that plagued the Chinese – is corrosion from the molten salt. But this challenge is well understood today and already managed in other industry facilities, including concentrated solar power plants with molten salt storage. For what it’s worth, the IAEA claims that “no technological breakthroughs are required” for the corrosion issue (PDF).

So should we go ahead with thorium? As the Chinese and German examples show, more than one prototype will be needed. If each one comes at a price tag of 1 billion euros, we are talking about a lot of money. Maybe Goldman Sachs could pay for all of this out of the kitty, but that doesn’t mean thorium is the best option.

Even if they work as touted, thorium reactors would still produce some nuclear waste – and frankly, it’s not completely certain they would be inherently safe if there were an accident. Finding that out would cost billions. By the time we figured that out, the falling cost of solar + wind + storage would, no doubt, make thorium uninteresting. And we already know for certain that renewables are inherently safe.

Craig Morris (@PPchef) is the lead author of German Energy Transition. He is co-author of Energy Democracy, the first history of Germany’s Energiewende, and is currently Senior Fellow at the IASS.


Craig Morris

Craig Morris (@PPchef) is co-author of Energy Democracy, the first history of Germany’s Energiewende.


  1. Avatar
    James Wimberley says

    Articles like this will bring nuclear fans out of the woodwork. I can’t work out who they are. The nuclear industry is moribund, and surely incapable of organising or funding a competent astroturf operation. Financiers lost interest thirty years ago. Nuclear weapons people don’t show up on green blogs. Are the fans working in the industry, trying to convince themselves it has a future? Or contrarian hobbyists, the kind of people who complain about GMO crops, vaccinations, and wind turbine syndrome?

    BTW, an advocate for a new design of nuclear reactor has to deal with the timetable issue. Start tomorrow with a blank cheque, and you might have working experimental reactors by 2025. Commercial pilots by 2035. Large-scale deployment (in the hundreds) starting in 2045. By then the battle to stabilise the climate will have been won or lost. Oh, they will say, the delays are all because of safety fusspots imposing too many regulations, and changing them all the time. Give the innovators a free hand, and you will see quick results! I’d sooner believe in antigravity machines than in the public’s acceptance of the Soviet approach to reactor safety.

  2. Avatar
    Dennis says

    It’s not crackpots who are promoting ‘green nuclear’, but those of us who believe in global warming and want to use all available approaches. A recent study from a green energy think tank has concluded that it will not be possible not only on the basis of cost (which will continue to decline) but also because of simple math:

    “Accommodating the 46,480 solar PV plants envisioned for the U.S. in the WWS vision would take up 650,720 square miles, almost 20% of the lower 48 states. This is close in size to the combined areas of Texas, California, Arizona, and Nevada.
    A 1000-megawatt (MV) wind farm would use up to 360 square miles of land to produce the same amount of energy as a 1000-MV nuclear plant.
    To meet 8% of the U.K.’s energy needs, one would have to build 44,000 offshore wind turbines; these would have an area of 13,000 square miles, which would fill the entire 3000 km coastline of the U.K. with a strip 4 km wide.
    To replace the 440 MW of U.S. generation expected to be retired over the next 25 years, it would take 29.3 billion solar PV panels and 4.4 million battery modules. The area covered by these panels would be equal to that of the state of New Jersey. To produce this many panels, it would take 929 years, assuming they could be built at the pace of one per second.”

    The other part of green energy optimism that proves unworkable is political, trying to get western nations to agree on lowering standard of living is just not going to happen.

    I am convinced that the Thorium MSR is a viable plan, and yes it will take more than one research plant. They are being built today in China and India. Don’t confuse them with the Soviet-era plants, and don’t confuse the issue that they can make uranium 233 from thorium, because they can just as easily reprocess waste fuel from conventional reactors.

  3. Avatar
    Ben Paulos says

    I had to look up the source for the claim “Dennis” made in his comments about the Wind-Water-Sun research. He said it was from a “green think tank.” In fact it was from a group called Friends of Science, based in Calgary, the center of the Canadian oil and tar sands industry.

    Their web site says “Friends of Science have spent a decade reviewing a broad spectrum of literature on climate change and have concluded the sun is the main driver of climate change, not carbon dioxide (CO2).”

    Here is some more background:

  4. Avatar
    Alan Reinhart says

    Some how the complaints against thorium are a bit vague and I’m still not understanding why you are against it. I will give you that, under current political and frightened,misled public opinion, that it could take much too long to perfect the MSRs. Fear, not technology, has stifled and nearly destroyed a promising future.

  5. Avatar
    PhilH says

    The numbers quoted by Dennis below are seriously out, even allowing for his confusion of GW, MW & MV units and miles & kilometers.

    In the UK, 44,000 offshore turbines of a typical 5MW size would have a capacity of 220GW and an average output of 100GW, which is enough to supply all the UK’s energy needs (deliver all its electricity, run all its transport, provide all its heating, etc), not just 8%, and still have some for export. They would cover 40,000km2, which is &#189% of the UK’s Exclusive Economic Zone waters.

    In the US, 440GW of fossil-fuel stations provide about 200GW average output, which could be supplied by 4bn (not 30bn) PV panels, which is about 13 per American, occupying a 14′ by 14′ square, which should be fittable on existing home roofs, workplace roofs and carports.

    If his belief in the economics of thorium reactors are based on similar factor-of-10 errors, it’s no wonder that the people who know the real figures aren’t funding them.

  6. Avatar
    PhilH says

    In the comment below, it should read: “They would cover 40,000km2, which is ½% of the UK’s Exclusive Economic Zone waters”.

    Additionally, the WWS report says in Table 2 that the 46,480 50MW PV plants would occupy 0.2% of the US, not 0.2 of it as misreported by Friends of Science and Dennis. But what’s a factor of 100 in a post-truth world?

  7. Avatar
    heinbloed says

    Thanks for checking the numbers, PhilH. And for checking the background information,Ben Paulos.

  8. Avatar

    So no word on efficiency, or ability to exhaust the energy and potential radioactivity in the fuel, or the fact that thorium can be, and is, stored in piles, on-ground in China because it has a half-life of billions of years and is a restproduct from rare earth metal industry, or that it is orders of magnitude more common than the useful uranium isotope, or that there is present development in China and India. Instead of quoting numbers I can’t verify, search the internet to see what Kirk Sorensen from Nasa has to say! The important question might be “by whom”, and not “when” or “if”, molten salt Thorium reactors are realized.

  9. Avatar
    Nicolai Grenovski says

    Chris, are you aware of Thor Energy in Norway?

    They have a process, which successfully passed testing and being tested in the UK, to use Thorium (MOX) as a fuel in conventional reactors >90% of the world’s reactors are light water reactors (including new EPRs) that can use Thorium MOX.

    The benefits are that Thorium is cheaper, far more common than Uranium and because of its high melting point, it is even less likely to melt down.
    In addition to this, its use with MOX is a mechanism by which we can rid ourselves of Plutonium which does away with the need for long-term storage.

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