Radiation leak at nuke plant, but reactor 'intact'

TOKYO: Radiation leaked from a quake-hit Japanese nuclear plant Saturday, but the government moved to calm fears of meltdown and said a huge explosion had not ruptured the container surrounding the reactor.

An evacuation order for tens of thousands of residents was expanded to 20 kilometres (12 miles) around the Fukushima plant, where authorities scrambled to control rising temperatures and pressure inside several reactors.

The fear was that evaporating cooling liquid would expose the fuel rods to air, triggering a nuclear meltdown and major radiation leak.

Work was continuing to douse the site with sea water to reduce the temperature.

Japan's nuclear safety agency rated the accident at four on the international scale from 0 to 7. The 1979 Three Mile Island accident in the United States was rated five while the 1986 Chernobyl disaster was a seven.

"Right now we are considering the accident should be rated four," an official of Japan's Nuclear and Industrial Safety Agency said early Sunday, adding that the rating may be changed according to how the situation develops.

Japan had on Friday declared an atomic emergency amid growing international concern over its reactors after an 8.9 magnitude earthquake, the biggest in Japan's history, unleashed tsunamis that destroyed everything in their path.

The US Air Force, which has many bases in Japan, on Friday delivered coolant to a nuclear plant there, US Secretary of State Hillary Clinton said that day, without specifying which plant.

The operator Tokyo Electric Power (Tepco) pumped water into the Fukushima No. 1 plant and released steam to depressurise the hut containers, an action that experts say will release a certain amount of radioactive vapour.

Tepco said that, at its highest level, the hourly radiation inside the plant reached 1,015 micro sievert before the blast -- equivalent to the permissible exposure for people over one year.

In the afternoon a huge explosion ripped through the plant, and a massive plume of white smoke billowed into the sky, raising fears the steel reactor had been destroyed.

But Tepco later said it was the structure encasing the reactor that had collapsed, saying that this took place at the time of an earthquake aftershock, and that the steel reactor inside it was not ruptured. (AFP)