>Nuclear power plants are designed with scenarios like terrorist attacks in mind
Look, the world trade center was 'designed with scenarios like plane crashes in mind'. The towers still fell :( No one really expected bad guys to use planes as weapons, and things to get so hot.
Fukushima was designed with tsunamis in mind. No one expected a tsunami so far outside the design envelope.
That's fine, you can't economically design for every eventuality, so you define an envelope.
If you design a system to be robust against the 1 in 50 year Tsunami/attack/whatever, then after 50 years, all events are likely going to be in your margin of safety. If you extrapolate purely from that observed data, you are going to get a real shock 70 years in when a 1-in-100-years storm/attack/whatever occurs.
It's great that things are designed for robustness. But it then takes a long time for the true costs to be naively estimated just by looking at historical data.
Analysis based on 'the problems we have had' is fundamentally rearward looking. There's a value to it, but it's not the complete story. I argue its particularly dangerous with a technology that has rare but catastrophic failure modes.
In particular, it is flawed to look at a limited history of a tech with rare but catastrophic failures/costs, and empirically compare against a tech with more normally distributed failures/costs.
I do understand your point, by the way. I completely agree that we can't account for every possible scenario using history alone. But there's a balance between over-engineering for fantastical events that are difficult to predict and keeping things affordable. Equally, at some point you have to weigh up the very present and deadly effects of coal power plants against the low probability, high impact of a nuclear power plant going boom.
[1] https://carnegieendowment.org/2012/03/06/why-fukushima-was-p...
