[fighterpilot]

Likewise, Lehman may not even necessarily represent the tail risk of a financial crisis, after all the other banks didn't also collapse.

Extreme Value Theory tells us it is hard to calibrate estimates of tail risk but it's not as if we have no data and no grounds with which to do it in the case of nuclear power.

Flippant analogies that are actually flawed analogies upon close examination aren't helping. If there's reason to believe that modern nuclear plant designs could lead to large scale death with a non-trivial probability, far beyond the scale of Chernobyl which had a very small death count relatively speaking, then the case for this needs to be made by outlining the actual mechanism by which this can happen.

Regarding the significantly improved safety of modern plant designs, this was addressed by other commenters.