Explosion rocks reactor

High levels of radiation leaked from a crippled nuclear plant in tsunami-ravaged northeastern Japan after a third reactor was rocked by an explosion today and a fourth caught fire in a dramatic escalation of the 4-day-old catastrophe.

Workers were striving to stabilize three reactors at the Fukushima Dai-ichi nuclear plant in Fukushima state that exploded in the wake of Friday’s quake and tsunami. Officials said 50 workers, all of them wearing protective radiation gear and working at great personal risk, were still trying to put water into the reactors to cool them.

The crisis at the complex is already the worst nuclear accident since the Chernobyl reactor disaster a quarter-century ago.

People ordered to stay indoors

The Japanese government warned 140,000 people near the nuclear complex to stay indoors to avoid exposure. Tokyo also reported slightly elevated radiation levels, but officials said the increase was too small to threaten the 39 million people in and around the capital, about 170 miles away.

In a nationally televised statement, Prime Minister Naoto Kan warned there is a danger of more leaks and told people living within 19 miles of the complex to stay indoors to avoid exposure that could make people sick. "Please do not go outside. Please stay indoors," Chief Cabinet Secretary Yukio Edano told residents in the danger zone. Some 70,000 people had already been evacuated from a 12-mile radius around the complex.

U.S. offers assistance

President Barack Obama proclaimed yesterday that the United States will stand by longtime ally Japan, saying he has offered any assistance the U.S. can provide.

Aside from several U.S. Navy ships already involved in the relief effort, the Nuclear Regulatory Commission has sent two technical experts to Japan, officials said. The Department of Energy has also dispatched reactor experts and emergency response experts to Japan.

The U.S. assistance operation will ramp up with the arrival of U.S. Marines, who are expected to use the USS Tortuga amphibious dock ship to ferry some 300 Japanese civil defense workers close to the disaster area today.