A lot of people now don't realise that radiation is dangerous. There have been several mass-casualty incidents caused by radioactive materials turning up at scr

A lot of people now don't realise that radiation is dangerous. There have been several mass-casualty incidents caused by radioactive materials turning up at scrapyards in developing countries. The people involved just didn't make the connection between a weird-looking piece of metal and becoming incredibly sick. Figuring out how to correctly store and label radioactive materials is far from hypothetical. There are numerous long-term risks that don't involve the collapse of civilisation. The use of radioactive materials might become largely obsolete and the knowledge of it might become obscure trivia; such a society would have little awareness of the risks of radiation and very limited skills, equipment and infrastructure to deal with it. Geopolitical changes might put the nuclear waste site within the territory of an isolationist theocracy that rejects modern science. Changes in language might mean that the risks of radiation are fully understood, but the words and symbols we use to mark it might be incomprehensible. Data rots with remarkable speed if it isn't maintained with constant vigilance. It's fairly common for construction crews to accidentally dig into an old sewer or an electrical conduit because records weren't properly maintained. Non-trivial quantities of radioactive materials have been lost due to accidents and administrative errors. Russia lost track of dozens of nuclear warheads and vast quantities of fissile material after the fall of the Soviet Union. Over a timescale of centuries or millennia, it's entirely conceivable that the location of a major nuclear waste site could be completely forgotten. https://en.wikipedia.org/wiki/Samut_Prakan_radiation_accident https://en.wikipedia.org/wiki/Samut_Prakan_radiation_acciden... https://en.wikipedia.org/wiki/Goi%C3%A2nia_accident https://en.wikipedia.org/wiki/Goi%C3%A2nia_accident