"When the massive tsunami smacked into Fukushima Daiichi, the nuclear power plant was stacked high with more uranium than it was originally designed to hold and had repeatedly missed mandatory safety checks over the past decade. The Fukushima plant that has spun into partial meltdown and spewed out plumes of radiation had become a growing depot for spent fuel in a way the American engineers who designed the reactors 50 years earlier had never envisioned, according to company documents and outside experts."
"At the time of the March 11 earthquake, the reactor buildings at Fukushima held the equivalent of almost six years of the highly radioactive uranium fuel rods produced by the plant, according to a presentation by Tokyo Electric Power Co to a conference organized by the International Atomic Energy Agency.
Along with questions about whether Tokyo Electric officials waited too long to pump sea water into the plants and abandon hope of saving them, the utility and regulators are certain to face scrutiny on the fateful decision to store most of the plant's spent fuel rods inside the reactor buildings rather than invest in other potentially safer storage options.
That debate has direct implications for nuclear policy in the United States about whether changes enacted after the September 11, 2001 attacks go far enough to protect potentially vulnerable fuel stored at the nearly two dozen U.S. power plants that have the same design as the Fukushima Daiichi plant, experts say."