Nuclear Plants have not been designed for being flooded by tsunami nor for earthquakes of the sort anticipated in the near-term.
Levees all across America–and perhaps in other parts of the world–have not been designed for “heavy weather” of the sort that destroyed the largest “conventional” levee protecting the city of New Orleans.
This is a short-coming that will ultimately be fatal for more than one community, and it is not being corrected by anyone.
Quake Motion May Have Exceeded Plant's Design
Earthquake simulator gives model levee a big shake