TOKYO — One week after an earthquake and tsunami spawned a nuclear crisis, the Japanese government conceded Friday it was slow to respond to the disaster and welcomed ever-growing help from the United States in hopes of preventing a complete meltdown at the Fukushima Dai-ichi power plant.
The government raised the accident classification for the nuclear crisis from Level 4 to Level 5 on a seven-level international scale. That put it on a par with the Three Mile Island accident near Harrisburg, Pa., in 1979 and signified its consequences went beyond the area.
The entire world was on alert, watching for any evidence of dangerous spikes in radioactivity spreading from the six-reactor facility, or that damage to the Japanese economy might send ripple effects around the globe.
As day broke today, steam rose from Unit 3, an unwelcome development if not a new one that signaled continuing problems. Emergency crews faced two challenges at the plant: 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.
"In hindsight, we could have moved a little quicker in assessing the situation and coordinating all that information and provided it faster," Chief Cabinet Secretary Yukio Edano said on Friday.
Crucial to the effort to regain control over the plant is laying a new power line to the complex, which would allow operators to restore cooling systems. The Tokyo Electric Power Co. said today that it had attached an electrical line to the blacked-out facility. But 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. Even when removed from reactors, uranium rods are still hot and must be cooled for months, possibly longer, to prevent them from heating up again and emitting radioactivity.
Edano said Tokyo was asking Washington for additional help, a change from a few days ago, when Japanese officials disagreed with U.S. assessments of the severity of the problem.
Radiation now in U.S.
Faint traces of very low levels of radiation from the nuclear plant in Japan have been detected in Sacramento, Calif., European officials said Friday. Health experts said the plume of radiation would have no health consequences in the United States.
Information from the New York Times was used in this report.