The meme that coal plants emit more radioactivity than nuclear power plants originated with this Scientific American article [1] (linked somewhere else in this thread too). The article has the title "Coal Ash Is More Radioactive Than Nuclear Waste". The comparison is obviously preposterous, nuclear waste is probably trillions of times more radioactive than coal ash. When SA realized the mistake they added an explanation just at the end of the article that states
"As a general clarification, ounce for ounce, coal ash released from a power plant delivers more radiation than nuclear waste shielded via water or dry cask storage." (emphasis mine)
By adding the qualification "shielded" the comparison becomes meaningless. Brazil nuts, bananas, beer, carrot juice and drinking water [2] all release more radiation than shielded nuclear waste.
Nowhere in the SA article they compare coal ash with Chernobyl of Fukushima.
[1] https://www.scientificamerican.com/article/coal-ash-is-more-...
[2] https://www.thoughtco.com/common-naturally-radioactive-foods...