Photo courtesy of Thorium Forum.
Thorium reactors have the potential the potential to be a less toxic and cheaper alternative to other nuclear fuel – but not without risk.
Unlike uranium and plutonium, thorium – although a radioactive material – isn’t fissile by itself. This means thorium reactors, or thorium itself, can create its own chain reactions . Neither can it be weaponized, or blow up by accident.
Thorium reactors also use liquid fuel, not solids, meaning there is no chance of a Chernobyl or Fukushima-style meltdown, as the fuel is already molten.
This fuel is kept at regular atmospheric pressure, so there is no chance of explosion from overpressure.
Finally, thorium produces much less toxic waste, and the waste decays at a much faster rate. This means it only has to be kept safe for around 300 years, as opposed to more than 10,000 for uranium waste.
The fuel cost for thorium reactors is only $0.00004/kwH, compared to $0.02/kWh for coal, another inexpensive fuel source.
While there would still be capital costs for installing thorium reactors (and the process has yet to be made commercially viable), regular nuclear reactors are twice as expensive to build.
Thorium is also more efficient, and can burn existing nuclear fuel in the process, using old waste to create new energy.
Thorium is 3-4 times more abundant (pdf) than coal.
It can be found all around the world, with major reserves estimated in the U.S., India, Brazil, South Africa, Australia, and Norway.
Image courtesy of the United States Geological Survey via the Massachusetts Institute of Technology.
Why isn’t thorium in use yet?
Thorium reactors have been researched since the ‘50s; however, they have yet to be made commercially viable.
This is because thorium itself doesn’t sustain its own nuclear reaction once it’s started. In other words, another fuel has to be introduced to keep it going.
Uranium and plutonium have so far been easier to exploit, and doubled up as weapons program for nuclear nations during the Cold War.
There is also the fear of proliferation that always haunts civilian nuclear programs. While thorium itself isn’t weaponizable, its byproducts could still be exploited, despite being extremely difficult to handle. Nascent nuclear programs like Iran or North Korea’s in particular could be able to do so.
Will we see thorium reactors in the near future?
Very possibly. In fact, India, a leader in the field, hope to use thorium power plants for 25% of its electricity by 2050.
At least two methods for exploiting thorium are reaching viability: the first is a a hybrid method that mixes plutonium fuel rods with a blanket of uranium and thorium.
This technology is already being developed and used in Russian power plants by the U.S. company Lightbridge.
The second method truly exploits its potential, however: only thorium or waste from other materials should be used. That’s the promise of Accelerator-Driven Systems, which aim to use particle beams (pdf) to spark a continued chain reaction.
Such a system isn’t likely to be perfected for years, however, making adoption of hybrid systems much more likely.