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The steam built up terrible pressure, generating hydrogen gas. But within an hour, the flooded generators failed.Īs the pumps stopped, the water in the cores began to drop, and the reactors started to boil. The Fukushima Daiichi plant, run by the Tokyo Electric Power Company (TEPCO), had planned to use emergency diesel generators to continually pump cooling water to these reactors. But nuclear fuel requires cooling even when a plant is stopped. Control rods dropped into the cores, stopping the nuclear fission of uranium. “Then I wondered about the safety of the nuclear plants.”Įleven nuclear reactors at four power plants automatically shut down when they detected the earthquake’s vibrations. “I saw the images of the Sendai airport being swept away by the tsunami,” Hiroaki later told historian Katsuya Hirano. Residents had only minutes of warning, and even evacuation locations were inundated. The waves reached heights of 128 feet, topping protective seawalls, and traveling inland for six miles to the town of Sendai. That’s when the next disaster hit: In less than an hour, the first of many tsunamis overcame the country’s northern shores. When the ground stilled, people looked to the ocean. The 9.0 magnitude earthquake was powerful enough to shorten the Earth’s day, throwing an extra wobble into its rotation. The seabed rose up 16 stories, and slipped sideways 165 feet. A slippery clay layer helped the great pieces of crust slide, releasing centuries of stress. Fifteen miles beneath the surface of the sea, one tectonic plate rumbled beneath another. It was a gray, wet afternoon, and the 61-year-old nuclear engineer was hard at work when the earthquake hit. On March 11, 2011, Koide Hiroaki was in his laboratory in Kyoto, Japan.
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