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Authorities and local press need to double check the levels of risk for which US nukes were designed. The main design error leading to this crisis was that no one had a large enough nightmare. Although they survived the 9.0 quake they were only designed for 7.9 or 8.2 (I've seen both levels claimed). They were only designed for a 2m tsunami and got twice that. When they were built 40 years ago that may have been a plausible worst case scenario, but they should have known better for several years now. In hind sight a bigger sea wall would have been VERY cost effective.

Given the large number of unexpectedly bad natural disasters the past couple decades I suspect many risk estimates were low balled in the past. '100 year' floods seem to happen every 20 years and '500 year' ones are commonplace. They better not be designing midwestern nuke plants for only T3 tornadoes or we'll find how well a T5 can scatter radiation. Siting plants near large natural water supplies can be very beneficial- where'd they be without easy access to sea water now? But you need a generous safety margin of elevation. Run computer models of worst theoretically conceivable river floods, tsunamis, etc. Seattle area better model lava flows or lahars from Mt. Rainer.

Consider the probability that a natural disaster strong enough to break one thing could well break several things. I'd also like to see robots capable to investigating high radiation areas and debris strewn areas. That need has been obvious since Chernobyl. It's shocking that Japan apparently doesn't have such available. Our military has made much progress in robots in Iraq and Afghanistan. Some of that tech and experience needs to be spun off and pre-positioned for such use. It should be technically possible to remotely pilot helicopters for these water drops as well as those pump trucks. There may still be some radiation hazard involved in fueling and servicing them, but performance could be better without having to protect a pilot. A robot that could deliver and position a fire hose would also be great.

I guess the question always comes down to how conservative is conservative enough (not in the political sense, but from a design viewpoint). Right now in this country the seismic requirements for design basis earthquake is one twice as powerful as the most powerful seismic event for the region in which the plant is located. Maybe this experience will lead to an increase in that margin for new build, and reasonable retrofitting for existing units.

But the thing that sticks out like a sore thumb in this latest accident is the common mode failure. The plants withstood the seismic event. They shutdown upon detection of that, the diesels started when offsite power went out, everything was running until the tsunami came ashore. Anyone who has ever designed a system knows that you always try to avoid common mode failure where you can, but here things obviously were inadequate. I think that is where the focus will be in the "lessons learned" to come from all of this. And, historically, the industry has been pretty diligent in applying those lessons. I think we'll see that again here.