Thorium, a naturally occurring radioactive element named for the Norse god of thunder, was discovered in 1828. It is only found as its isotope, thorium-232, which is just one neutron shy of being the lifeblood (and bane) of today's nuclear industry, uranium-233.
Thorium has a lot of upsides. It's three times more abundant than uranium and about as common as lead. Australia, the United States, Turkey, India, Egypt, Norway, Canada and South Africa all have significant deposits.
The radioactive waste produced by a reactor running on thorium lasts 10 to 10,000 times less time than the waste from traditional uranium reactors. Thorium does not have to be enriched, saving time, effort and money.