Question Regarding Safety of Nuclear Plants In The U.S.

The disaster in Japan raised questions and concerns about the safety of U.S. plants; parallel concerns and lessons that may apply here; i.e., of earthquakes and tsunamis. Well, it was reported that the Japanese nuclear power plants were knocked out by the tsunami and not the earthquake. So, is there a concern that American nuclear plants may be vulnerable to increasingly severe flooding events, recorded over the past decade as a result of climate change? Floods wreacked much destruction on affected communities and knocked out power in areas that were under water, as in a tsunami. Wouldn't flood damage pose as potentially serious a problem to nuclear plants, similar to a tsunami water damage, if backup power fails? Just a thought, assuming there are nuclear plants in the U.S. built on flood zones.