I may be wrong but I recall one of the very early Nuclear power plants built in the US, Alabama comes to mind. Had a fire started by a guy looking for something using a candle, very close to a major meltdown. I just googled it. Here is the link.
https://www.neimagazine.com/features/featureremembering-the-browns-ferry-fire-40-years-on-4578707/#:~:text=On%20March%2022%2C%201975%2C%20a,fire%20protection%20in%20nuclear%20plants.
