The problem which nuclear disasters have that almost all other disasters don't is the permanence of danger over such a large area. There have been plenty of large-scale chemical or industrial disasters - everything from Bhopal to Tianjing to Agent Orange to Deepwater Horizon - but they have the common property that the smoke clears and it's possible to neutralise, disperse or otherwise clean up the mess. Whereas Chernobyl and Fukushima are going to have exclusion zones that must remain covered for our entire lifetimes.