coal plants, even so-called “clean coal” emit more radiation in one year than a nuclear plant does over its entire lifetimeThat is incorrect. You may be thinking of this Scientific American article:
"Coal Ash Is More Radioactive Than Nuclear Waste"
https://www.scientificamerican.com/article/coal-ash-is-more-...
Which is a garbled retelling of this 1978 report:
"Radiological Impact of Airborne Effluents of Coal and Nuclear Plants"
https://science.sciencemag.org/content/202/4372/1045.abstrac...
The point of the 1978 report was that radioactive elements from coal are more likely to be concentrated in the food supply and retained in the body than radioactive elements released from power reactors. That leads to an effective higher radiation dose to people under their modeling assumptions. But nuclear reactors release more becquerels (or curies, to use the older unit) of radioactive material to the environment.
You can see this difference if you look at the original publication via sci-hub.
https://sci-hub.se/10.1126/science.202.4372.1045
Table 2 shows an estimated airborne release of about 1.2 curies per year of radionuclides from a 1000 MWe coal plant.
Table 3 shows shows an estimated airborne release in excess of 5000 curies per year of radionuclides from a 1000 MWe nuclear reactor.
But since the reactor radionuclides do not biologically concentrate in food or bones, they are dispersed throughout the environment and human exposure is small.
In table 5 you can see that the whole body population dose commitments for the different sources, in man-rem/year, are 18-23 for coal (depending on stack height) and 13 for a nuclear reactor. So coal is worse but far from 50x worse. Looking exclusively at bone exposure, coal can be an order of magnitude worse since radium released from coal behaves chemically like calcium and concentrates in bones.