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Is thorium the nuclear alternative?

Desperate to be seen to be doing something (or is it because they are afraid of upsetting the powers that be) Governments worldwide are plumping for nuclear power rather than renewable energy to counter global warming. As we reported in the last two issues of Green Health Watch, this makes things look pretty bleak, what with (i) the huge potential for radioactive contamination and (ii) the fast vanishing supplies of high-quality uranium ore. Another alternative, albeit nuclear, was rejected by the European Commission in 1999 and 2000: a much safer way to produce nuclear energy called 'accelerator-driven system (ADS)' using a much less radioactive substance, thorium.

Accelerator-driven systems
In an 'accelerator-driven system' (ADS), a very strong external beam of protons is needed to trigger and maintain the heat-generating reactions. If a reaction appears to be getting out of control, you simply switch the proton beam off. In an ADS, the chain reaction which can become an atomic bomb or melt down a conventional reactor, could only occur through utter negligence or sabotage by an insider. A fault or, for instance, a bomb, would halt the reaction instantly. On the other hand, a terrorist bomb on a conventional reactor could contaminate land and people for hundreds, may be thousands of miles. Professor Egil Lillestol* estimates that the technology would require only 550 million euros and 15 years to develop. One major remaining problem is how to safely contain the molten lead (highly corrosive) used in the ADS process.

There is three times as much thorium as uranium in the Earth's crust. It produces 250 times more energy than uranium. Thorium waste loses its radioactivity in hundreds of years rather than tens of thousands. So what's the problem? Australia has the world's largest reserves of thorium, but India, which is sitting on about a quarter, has already planned its transition to ADS-thorium reactors.

Egil believes that the prime objection to both EU and global investment in ADS-thorium technology is more political than scientific. The countries which currently supply or process uranium ore are, understandably, not supportive. Nor are the countries which are still jealously guarding nuclear-uranium know-how. Those which have ADS-thorium know-how are also, to some degree, keeping it to themselves and working on different prototypes rather than pooling their expertise. Developing ADS-thorium technology within a relevant global warming timescale will demand (i) an acceptance that global power balance will shift from oil and uranium-owning nations to thorium-owning nations, and (ii) an unprecedented level of international cooperation and sharing.

* professor at the Institute of Physics and Technology, University of Bergen (Norway)


12899) Helen Brown. The Independent 13.12.06


Thorium - other benefits

Thorium offers other important benefits over uranium:

  • Add uranium, plutonium or any other radioactive 'actinide' metal into the mix and the thorium fuel process incinerates these elements.
  • Thorium-fuelled nuclear power stations could not only generate power but also solve the thorny problem of disposing of existing nuclear waste
  • Mining and refining thorium ore is simpler and cleaner than mining and refining uranium ore
  • The thorium fuel process could also be used to manufacture fuel for conventional uranium-fuelled power stations, reducing the need for further uranium mining or plutonium manufacture (other than the plutonium the politicians believe they need for weapons)
  • It is not possible to make weapons-grade materials from thorium

(12624) Tim Dean. Cosmos Online 15.4.07