IEEE Spectrum has an interesting and smart interview with Tsuneo Futami, who ran the Fukushima nuclear reactors for the Tokyo Electric Power Company before leaving to teach at Japanese universities. It provides great context for how the power plant's operators thought about what was possible and probable.
The scale of the Fukushima Dai-1 accident was far beyond my imagination. When I was superintendent, I could not have imagined that all electricity including battery power for units 1 through 4 would be completely lost at the same time, and would not be restored for more than 9 days.. At first, I thought that the diesel generator for each reactor automatically started, so I was sure that they could bring the plant to a cold shut down, although there would be many difficulties.
Read the full story at IEEE Spectrum.