“Thunder is good, thunder is impressive, but it is lightning that does the work.” – Mark Twain
The Norse god Thor is the ultimate symbol of strength. Often depicted wielding a powerful hammer, Thor is probably the most popular god of Germanic paganism. Thor’s influence on modern culture continues to reverberate, making appearances in books, poems, and blockbuster films. He even has a day of the week named after him (Thursday = “Thor’s Day”). In short, Thor is everywhere.
When Swedish chemist Jons Jakob Berzelius discovered a new silvery-white metal in 1828, he was quick to name it Thorium, in a nod to the popularity of Thor in Scandinavia. Now, while having your own day of the week is impressive, getting a chemical element named after you seems like an even higher honor. Sure, there are more spots on the periodic table than in the 7-day week, and Thursday is a pretty good day (especially compared to Tuesday), it’s not like it’s part of the weekend or anything.
Thorium is a relatively stable metal, although it will tarnish over time if small traces of its oxide are present. It is also abundant, existing in average concentrations of 6 parts per million in typical soils. The metal is mined industrially as a byproduct of the production of rare-earth metals – a topic we’ve covered in a prior piece. What makes thorium interesting to many is the fact that it can be used as a fuel for nuclear reactors, albeit not without some tinkering. It also occupies a growing share of mind in some nuclear energy circles, as evidenced by the number of comments and emails we receive urging us to explore it for a future Doomberg piece.
And here we are.
More than 99.9% of the thorium found on earth exists as thorium-232, a mildly radioactive isotope with a half-life of over 14 billion years. When thorium-232 is irradiated with neutrons, it becomes thorium-233, which eventually transmutes into uranium-233 – a fissile material suitable for use as a nuclear fuel. The thorium fuel cycle is well understood and has been studied for decades. It has recently come back into the popular lexicon, influenced largely by projects in China and India. Some enthusiasts think thorium is a potential magic bullet solution to our energy problems, while others are less sanguine in their appraisal. The renewed interest centers on three factors: thorium’s abundance, its waste profile, and the new processing technology it enables. We review each in turn and draw our own conclusion, so let’s dig in.