Thorium first

CERN estimates that 1 ton of thorium is capable of producing as much energy as 200 tons of uranium. This is because 100% of thorium is available for fission where uranium is only .7% of usable U 235 and must be enriched to get rid of the unwanted U 238. Thorium is about 3-4 times more common than uranium in the earth's crust. Thorium's ore, monazite, generally contains higher concentrations of thorium than the percentage of uranium found in its respective ore. This makes thorium a more cost efficient and less environmentally damaging fuel source. Thorium is found in the waste products (tailings) in other mining such as iron and phosphate. Thorium is concentrated in coal ash. Over 5 billion tons of coal ash have been produced in the U.S. over the last century, with roughly 110–140 million tons generated annually. Ash from the typical coal power plant each year will contain 15,000 tons of thorium which according to Google AI could power the entire world for ten years.