Radiation levels at reactor rise after earthquake
The Japanese government declared its first-ever state of emergency at a nuclear power plant after Friday's 8.9-magnitude earthquake caused a problem in a cooling system, causing radiation levels in a reactor to rise to 1,000 times normal.
Japan's nuclear safety agency said some radiation escaped from the plant.
The government ordered 3,000 residents to leave the area.
The quake cut off power to the Fukushima Daiichi nuclear power plant, which is in Onahama city, about 270 kilometres northeast of Tokyo. A backup generator failed and the primary cooling system was not able to supply water to the plant's 460-megawatt No. 1 reactor.
Japanese nuclear safety official Yuji Kakizaki said plant workers were cooling the reactor with a less-effective secondary cooling system. Kakizaki said an emergency cooling system remains intact and ready to kick in if required to prevent a reactor meltdown.
Japan's nuclear safety agency said pressure inside the Fukushima No. 1 reactor has risen to 1.5 times the level considered normal. To reduce the pressure, slightly radioactive vapour will be released.
Yukio Edano, the chief cabinet secretary, said the amount of radioactive element in the vapor would be "very small."
"With evacuation in place and the ocean-bound wind, we can ensure the safety," Edano said early Saturday in a news conference.
Japan's nuclear safety agency said the radioactive vapour would not affect the environment or human health.
Plant workers were scrambling to restore the cooling water supply at the plant but there was no prospect of immediate success, The Associated Press reported. The U.S. offered to rush coolant to Japan, but a U.S. official later said the Japanese handled it themselves.
Builders plan for quakes
Kaoru Ishikawa, the Japanese ambassador to Canada, said all the nuclear power plants in Japan were built "bearing in mind the possibility of big earthquakes."
He said all the plants in the affected area were shut down automatically after the quake, but he noted the coolant problem at the Fukushima plant continued.
The International Atomic Energy Agency said Japanese authorities also reported a fire at the Onagawa nuclear plant. The fire has been extinguished.
"They say Onagawa, Fukushima-Daini and Tokai nuclear power plants were also shut down automatically, and no radiation release has been detected," the IAEA said in a statement posted online.