For varying definitions of successfully contained given all the radiation that poured into the ocean and polluted soil for miles around the plant. Let us also not forget that they were warned to raise their generators higher off the ground. The new specifications would have prevent the failure in the first place and we'd still have a nuclear power pant if they had spent the money when it mattered.
"Warned" by who? And how credible were these warnings? I know you think you know the difference between foresight and hindsight. But you don't. You have to understand when people knew what and how fast a very conservative bureaucracy responds to newly exposed risks.
Here's my understanding of the timeline for the tsunami risk assessment. From previous discussions on Slashdot, I gather it was realized before the earthquake that the risk of much higher tsunami had been underestimated. But this risk wasn't even revealed till 2001 (that's the oldest reference anyone has given me).
Then the various nuclear plants were instructed to review this risk some point after that with TEPCO completing their assessment of the Fukushima plant some point around 2008 or 2009. At that point, apparently, it was determined that the plant did not have adequate sea walls for the worst case.
At this point, you have various complicating factors such as the planned closure of these reactors over the next decade and the fact that nobody in the nuclear industry moves fast.
It is much like the levies in Louisiana that flooded the whole city. The army core of engineers had already recommended improvements that were not performed because nobody wanted to spent the few million it would have taken. So instead we spent 10s of billions cleaning up the mess.
Except that those risks have been known for a long time and the risk of New Orleans getting directly hit by a strong hurricane remain considerably higher than eastern Japan getting hit by very high tsunami. New Orleans still faces that same risk despite the levee upgrades.
For example, if a hurricane stalls over New Orleans, then it'll be just as flooded as it was that time. It's also worth noting that they still have the habit of appointing the sort of irresponsible leadership that led to the high loss of life in the Katrina disaster.