TBF, historically most nations allow "temporary" storage of spent nuclear fuel cells in perpetually filled pools or running water, which have the potential to run out and cause a nuclear apocalypse via irradiating everything on the surface of the earth. Currently millions of spent rods are stored "temporarily" in such pools which all together contain as much Cesium-137 as 30 Chernobyls in the USA alone.

It gets talked about a lot in "what if" scenarios about human extinction, because if Humanity died out then those pools will dry up and everything else will die alongside us.