[dfox]

The extent of damage and contamination certainly is human failure, mainly in accident response. My understanding is that the correct response to such a major loss of cooling on BWR is just to evacuate premises and do nothing (with the idea that the resulting excursion will obliterate the reactor but the dangerous fallout will remain inside the containment), the Fukushima operators tried to save the situation and thus made the impact worse.

[pdonis]

> the correct response to such a major loss of cooling on BWR is just to evacuate premises and do nothing

The problem at Fukushima wasn't a short-term loss of coolant; it was the long-term lack of backup cooling after the tsunami hit (by which point the reactor had already been shut down for about 45 minutes), because of poor siting of the backup generators and switchgear. The operators couldn't do anything about that, no matter what they did.

[dfox]

And that is exactly my point. In such situation just leaving the reactor be would cause destruction of the reactor and no major environmental impact, yet they misguidedly tried to save the situation and thus exacerbated the environmental impact.

Poor placement of backup systems is critical to process continuity, but in case of BWR mostly irrelevant to actual nuclear safety as long as you are willing to just write off the reactor (as you should) in case of major accident.

[pdonis]

> In such situation just leaving the reactor be would cause destruction of the reactor and no major environmental impact

I'm not sure the last part is true; as I understand it, there was a significant risk of a containment breach if decay heat removal was insufficient--not from the reactor cores themselves, but from the spent fuel pools.

I agree with you, though, that any attempt to save the reactor itself was doomed to failure once the tsunami hit and the backup cooling was taken out, so any actions taken toward that end were misguided.