The fundamental flaw in your response is that the Fukushima units had no design features to deal with a tsunami from the start, so analysis was never part of the equation.
The report commissioned by the Diet specifically pointed to active resitance on the part of TEPCO to resist documentation efforts that would support an increase to the height of the sea wall because they relied on historical data instead of geological data and more modern techniques for assessing the risk.
If you postulate a tsunami that breaches the wall, then you must analyze the plant to ensure it can withstand, and this was never done.
Exactly. Like an aircraft crash, more than one thing has to go wrong to produce the failure. This is reactor failure caused by long term mis-management of the technology, not the actual technology. No enhancement to the sea wall or improving back-up power redundancy, operator training, more intensive drills and simulations - the list goes on. In the 60's Fukushima was state of the art and the sea wall was built according to what was reasonable at the time.
Over time a belief system, 'Nuclear is Safe', developed. That produced a dogmatic skepticism, re-inforced by social proof so no actual challenges to the beleif system, even those based in science, were accepted. No machine is immune to human foley. And this is a point made in the
official report into the Fukushima disaster:
The Nuclear industry learned nothing from the lessons of Chernobyl.
In the case of Diablo, they designed the plant with the ability to withstand an earthquake from the start. They postulated the earthquake, performed the analysis, then obtained new earthquake information and validated that the existing analysis enveloped the new data.
Great. I haven't looked at Diablo Canyon. I was more concerned with San Onofre, Palo Verde, Davis Besse and, Indian Point but for different reasons. I'm glad SONGS is being decommissioned, it was on the other side of the Pacific in a fault zone with a greater density of fuel rods. It looks like the people who actually matter making the decisions about operating them in the US are smart enough to understand the dangers and not affected by social proof, but actual scientific proof.
None of this happened at Fukushima.
That's right - we all lost. The collusion between TEPCO and the regulator meant doing that work was actively resisted. It looks like there is a real movement in the NRC to grow some and challenge the operators of the reactors to shut them down if they can't be re-certified. This is a positive thing and the NRC should be commended for protecting the US from an accident caused by the same collusion that caused Fukushima to explode and melt down.
It looks like a really beautiful countryside from the pictures in the wiki too.