The Dark Side of Thorium

The element thorium, which many regard as a potential nuclear “wonder-fuel”, could be a greater proliferation threat than previously thought, scientists have warned. Writing in a Comment piece in the new issue of the journal, Nature, nuclear energy specialists from four British universities ,Dr Stephen F. Ashley and Dr. Geoffrey T. Parks from the University of Cambridge; Professor William J. Nuttall from The Open University; Professor Colin Boxall from Lancaster University and Professor Robin W. Grimes from Imperial College London suggest that, although thorium has been promoted as a superior fuel for future nuclear energy generation, it should not be regarded as inherently proliferation resistant. The piece highlights ways in which small quantities of uranium-233, a material useable in nuclear weapons, could be produced covertly from thorium, by chemically separating another isotope, protactinium-233, during its formation.

Press release at:

Nuclear energy: Thorium fuel has risks, DOI: 10.1038/492031a


  1. For more information on thorium, see:

    Dr. Arjun Makhijani on the downsides of the proposed thorium reactors and why solar power will save money and save lives

    This includes discussion of proliferation questions.

    This also includes discussion of the experimental Liquid Fuel Thorium Reactor at Oak Ridge National Laboratory. Decades later, they still have not figured out how to deal with the mess that was left behind.

  2. This proliferation issue is a red herring.
    The simple solution would be to restrict the use of Thorium reactors to the countries that already possess nuclear weapons. It turns out that these countries are also the largest producers of greenhouse gasses.
    If these countries developed Thorium reactors and thus stopped using coal and oil, it would result in an 85% reduction in greenhouse gas emission.

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