The issues here is what is your worst case when you loose your cooling. After Three Mile Island and Fukushima we have some answers for their respective designs: pressurized water reactors which have everything "hot" inside the classic dome also keep enough of that hot stuff in it, boiling water reactors that have things spread out in a rather complicated design don't.
Ok, this is a safer design. Anyway, my point is that loosing the cooling system of an active nuclear plant is much worse than loosing the cooling system of the shutdown nuclear plant (but don't try that at home). So it's not necessary to rush to dismantle the nuclear material, because of the fear of a tsunami. Those material should be handled properly.
And the insane Chernobyl design....