The reactor was shut down soon after the quake, but the fuel rods in the reactor remained hot, both in terms of temperature and radioactivity. With the area's electrical power knocked out, the reactor's cooling system failed, and so did backup diesel generators meant to keep the system running. The Associated Press reported that temperatures at the reactor were running 150 percent higher than normal.
"The quake has affected Japan's power structure and grid in a way that is difficult to comprehend at this point," according to Graham Kent, Nevada Seismological Laboratory director and University of Nevada professor of geological sciences. "The epicenter is not just one dot, 100 miles offshore. The rupture in this case is the length of the California coastline. That's why the damage is so widespread."
Speaking at the White House earlier today, Secretary of State Hillary Clinton said U.S. Air Force planes were delivering "some really important coolant" to the 40-year-old plant, which is 170 miles north of Tokyo. The distressed reactor is one of six at the plant, which is run by the Tokyo Electric Power Co.
Kent cited the Loma Prieta earthquake—which hit near San Francisco in 1989 and measured about 7 on the Richter Scale—to put the scale of Japanese quake into perspective. "The Loma Prieta rupture was 20 to 30 kilometers long," he said. "With the magnitude 9 quake in Japan, the rupture runs basically the length of the country. It has hamstrung the nation's whole infrastructure."