[roenxi]

> The choice of DBA tsunami height was clearly an underestimate, and underestimates were identified for Fukushima and other plants prior to the accident but not acted upon.

Not much of a swiss cheese failure then though. The failure is just that they committed hard to an assumption that was wrong.

My point is that unless it is actually an example of multiple failures lining up then this is a bad example of a swiss-cheese model. Seems to be an example of a tsunami hitting a plant that wasn't designed to cope with it. And a plant with owners who were committed to not designing against that tsunami despite being told that it could happen. It is a one-hole cheese if the plant was performing as it was designed to. The stance was that if a certain scenario eventuated then the plant was expected to fail and that is what happened.

Swiss cheese failures are there are supposed to be a number of independent or semi-independent controls in different systems that all fail leading to an outcome. This is just that they explicitly chose not to prepare for a certain outcome. Not a lot of systems failing; it even seems like a pretty reasonable place to draw the line for failure if we look at the outcomes. Expensive, unlikely, not much actual harm done to people and likely to be forgotten in a few decades.

[icehawk]

I don't think you understand how a swiss cheese failure happens. They're not independent or semi-independent. Latent failures, expose active failures, like:

"Committed hard to an assumption that was wrong"

Then causes damage to the seawater pumps along the shoreline, and flooded emergency diesel generators.

That causes total loss of AC and DC power.

Loss of AC and DC power causes the reactor to overheat.