Japan warns of radiation leak

SOMA, Japan -- Radiation leaked from a crippled nuclear plant in tsunami-ravaged northeastern Japan after a third reactor was rocked by an explosion Tuesday and a fourth caught fire in a dramatic escalation of the 4-day-old catastrophe. The government warned anyone nearby to stay indoors to avoid exposure.

In a nationally televised statement, Prime Minister Naoto Kan said radiation has spread from four reactors of the Fukushima Dai-ichi nuclear plant in Fukushima prefecture, one of the hardest-hit in Friday's 9.0-magnitude earthquake and the ensuing tsunami.

"The level seems very high, and there is still a very high risk of more radiation coming out," Kan said. "We are making utmost efforts to prevent further explosions and radiation leaks."

This is the worst nuclear crisis Japan has faced since the atomic bombing of Hiroshima and Nagasaki during World War II. It is also the first time that such a grave nuclear threat has been raised in the world since a nuclear power plant in Chernobyl, Russia, exploded in 1986.

Kan warned there are dangers of more leaks and told people living within 19 miles of the Fukushima Dai-ichi complex to stay indoors to avoid radiation sickness.

About 180,000 people had already been evacuated from a 12-mile radius and it was not immediately clear how many people live in the outer radius for which the new warning was issued.

Three reactors at the power plant were in critical condition after Friday's quake, losing their ability to cool down and releasing some radiation. A fourth reactor that was unoperational caught fire on Tuesday and more radiation was released, Chief Cabinet Secretary Yukio Edano said.

The fire was put out. Even though it was unoperational, the fourth reactor was believed to be the source of elevated radiation levels because of the hydrogen release that triggered the fire.

"Now we are talking about levels that can damage human health," Edano said. "These are readings taken near the area where we believe the releases are happening. Far away, the levels should be lower."

He said a reactor whose containment building caught fire Monday has not contributed greatly to the increased radiation. The radiation level around one of the reactors stood at 400,000 microsiverts per hour, four times higher than the safe level.