I took it to mean he was talking about worst case disaster scenarios in general not just nuclear reactor related. The breaking of the levees in hurricane Katri

I took it to mean he was talking about worst case disaster scenarios in general not just nuclear reactor related. The breaking of the levees in hurricane Katrina and the collapse of the world trade center come to mind. For example in the towers collapse the fire weakened the structural supports even though they were designed to withstand the impact.