KAZO, Japan — The ground started to buck at the Fukushima Daiichi nuclear power plant, and Masayuki Ishizawa could scarcely stay on his feet. Helmet in hand, he ran from a workers’ standby room outside the plant’s No. 3 reactor, near where he and a group of workers had been doing repair work. He saw a chimney and crane swaying like weeds. Everybody was shouting in a panic, he recalled.