Thorium is a chemical element with symbol Th and atomic number 90. A radioactive actinide metal, thorium is one of only two significantly radioactive elements that still occur naturally in large quantities as a primordial element (the other being uranium). It was discovered in 1828 by the Norwegian Reverend and amateur mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jöns Jakob Berzelius, who named it after Thor, the Norse god of thunder.
Three reasons Thorium stands out
- 1
Radioactive, might one day power cleaner nuclear reactors.
- 2
It is three to four times more abundant in the Earth's crust than uranium, giving it enormous potential as a future fuel.
- 3
Its most common isotope has a half-life of 14 billion years, longer than the current age of the universe.
An ancient isotope and a possible future fuel
Thorium-232 has a half-life comparable to the age of the universe, explaining why substantial deposits remain. It is fertile rather than directly fissile: reactors can convert it into uranium-233. Advocates see fuel-cycle advantages, although engineering, waste, economics, and proliferation questions remain.