In any major catastrophe they are abandoned and likely the meltdown and other issues could render whole areas uninhabitable. Might be manageable in certain power loss scenarios… but anything major and sudden like if you’re country suffered a nuclear attack or a major natural catastrophe and you survived I’d stay away from nuclear plants or chemical processing facilities.
this isn't chernobyl anymore, we have safe nuclear plants that have excellent emergecy shutdowns (the control rods are held up by electromagnets, and in a power loss they would instantly fall down, stopping the reactor)
with chemical companies, the idea is the same, but since they're handled by private corporations i wouldnt trust them that much with safety shut-offs in case of power loss. at most they'll have a backup battery and a diesel generator, which in a solar flare EMP will get destroyed too
now for only 140% the price!