Georgi Guninski's blog

The research paper concluded that there was a roughly 10 percent chance that a tsunami could test or overrun the defenses of the Fukushima Daiichi nuclear power plant within a 50-year span based on the most conservative assumptions. But Tokyo Electric did nothing to change its safety planning based on that study, which was presented at a nuclear engineering conference in Miami in July 2007. [1]

on top of it their measuring devices overflowed:

Those levels may be higher still, but authorities say 1,000 millisieverts is the upper limit of their measuring devices. [2]