Because nuclear power plants and the associated fuel cycle industry is incredibly dangerous and the participants have consistently lied about that danger for all of history? Note: not a tree hugger. I believe nuclear power (in conjunction with significant restrictions on consumption) must play a big part in decarbonization. But...so many lies for so long. Put down the Kool-Aid and admit these things are not safe and…
It's the history and detailed analysis of every nuclear accident, from the discovery of the radium to current days. You'll learn in passing that people used to drink radioactive cola to "improve" their health...
My main take away is that if you don't know exactly what you're doing, nuclear will kill you very very quickly. It's been quite reassuring about the security of existing plants