
My thesis is actually somewhat related to this all. Coal beds, being a sedimentary formation, collects a lot of other elements into its minerals compared to its pure carbon content. Any sediments coming from upstream can become trapped. U/Th is relatively common in granite and erodes out and is constituted in minerals within coal, most commonly pyrite. When burned, these elements become ash and coat EVERYTHING around the plant. So the entire plant is covered in layers of burnt uranium/thorium