FUKUSHIMA, Japan —
"Most of the motors and switchboards were submerged by the tsunami and they cannot be used," Nishiyama said.
Even once the power is reconnected, it is not clear if the cooling systems will still work.
The storage pools need a constant source of cooling water. When removed from reactors, uranium rods are still very hot and must be cooled for months, possibly longer, to prevent them from heating up again and emitting radioactivity.
People evacuated from around the plant, along with some emergency workers, have also tested positive for radiation exposure. Three firefighters needed to be decontaminated with showers, while among the 18 plant workers who tested positive, one absorbed about one-tenth tenth of the amount that might induce radiation poisoning.
As Japan crossed the one-week mark since the cascade of disasters began, the government conceded Friday it was slow to respond and welcomed ever-growing help from the U.S. in hopes of preventing a complete meltdown.
The United States has loaned military firefighting trucks to the Japanese, and has conducted overflights of the reactor site, strapping sophisticated pods onto aircraft to measure radiation aloft. Two tests conducted Thursday gave readings that U.S. Deputy Energy Secretary Daniel B. Poneman said reinforced the U.S. recommendation that people stay 50 miles (80 kilometers) away from the Fukushima plant. Japan has ordered only a 12-mile (20-kilometer) evacuation zone around the plant.
Emergency crews at the plant faced two continuing challenges: cooling the nuclear fuel in reactors where energy is generated, and cooling the adjacent pools where thousands of used nuclear fuel rods are stored in water.
The tsunami knocked out power to cooling systems at the nuclear plant and its six reactors. Since then, four have been hit by fires, explosions or partial meltdowns.
The government on Friday raised the accident classification for the nuclear crisis, putting it on a par with the Three Mile Island accident in Pennsylvania in 1979, and signifying that its consequences went beyond the local area.