TEPCO has released a detailed analysis of the tsunami that hit the Fukushima Daini Nuclear plant on March 11th, 2011. The analysis specifies the Inundation height, Inundation area, and the Run-up Height
Inundation Height – Considering the marks left on building facilities the height of the Tsunami waters reached 6.5meters to 7meters above the base level (Base Level = O.P. 0 meters) Inundation Depth was approximately 2 to 3 meters only at the south side of Unit 1 building.
Inundation Area – Most of the ocean-side area but no run-up over the hill to the main building area was found.
Run-up Height – Considering the vestiges on slope and road, approximately O.P. +14 meters.
It appears the Fukushima Daini nuclear plant was designed to be able to handle Tsunami waters that are only 5.2 meters above the Base level O.P. 0 meters. As the Tsunami waters reached 6.5 to 7 meters above base level the heat exchanger building was overwhelmed but the waters did not overwhelm the Turbine buildings or the reactor buildings the way it did to the Fukushima Daiichi nuclear plant.