Yup . . . a pump ran out of fuel because no one was watching it. Report in Japanese:
http://www.yomiuri.co.jp/science/news/20110314-OYT1T00843.htm Last para: ある東電幹部は「想定外の大地震による作業員の不足と、深刻な事故が重なったことで、（原発の『命綱』である）注水ポンプから目を離す事態が生じた」と漏らした。 My translation: A certain person at Tokyo Electric Power divulged the following: "This occurred because we do not have enough workers due to the unexpected severity of the earthquake, so there was no one keeping an eye on the pump being used to fill the reactor vessel. You might call that pump the reactor's vital 'lifeline.'" This demonstrates that the limits of technology are defined not by the genius of inventors, but by the competence under stress of the people who have to use the technology. - Jed
