(AP) — A nuclear power plant damaged by fire and explosions emitted a burst of radiation Tuesday, panicking an already edgy Japan and leaving the government struggling to contain a spiraling crisis caused by last week’s earthquake and tsunami.
Radiation levels in areas around the nuclear plant, which rose early in the afternoon, appeared to subside by evening, officials said. But the unease remained in a country trying to recover from the massive disasters that are believed to have killed more than 10,000 people and battered the world’s third-largest economy.
The leak caused the government to order 140,000 people living within 20 miles of the plant to seal themselves indoors to avoid exposure and declared a ban on commercial air traffic through the area. Worries about radiation rippled through Tokyo and other areas far beyond that cordon. The stock market plunged for a second day, dropping 10 percent. The troubles cascaded Tuesday at the Fukushima Dai-ichi plant, where there have already been explosions at two reactor buildings since Friday’s disasters.
An explosion at a third reactor blasted a 26-foot (8-meter) hole in the building and, experts said, damaged a vessel below the reactor, although not the reactor core. Three hours later, a fire broke out at a fourth reactor, which had been offline for maintenance.
In a nationally televised address, Prime Minister Naoto Kan said radiation had seeped from four of the plant’s six reactors.
The International Atomic Energy Agency said Japanese officials informed it that the fire was in a pool where used nuclear fuel rods are stored and that “radioactivity is being released directly into the atmosphere.”
Long after the fire was extinguished, a Japanese official said the pool might still be boiling. Depending on how bad the blast was at Unit 2, experts said more radioactive materials could seep out. If the water in the storage pond in Unit 4 boils away, the fuel rods could be exposed, leaking more virulent radiation.
Experts noted that much of the leaking radiation was apparently in steam from boiling water — and the falling radiation levels suggest the situation could be stabilizing.
Government spokesman Yukio Edano said the radiation leak potentially affected public health. But authorities and experts said the risks to the public diminished the farther the distance from the plant.
At its most intense, the leak released a radioactive dose in one hour at the site 400 times the amount a person normally receives in a year. Within six hours, that level had dropped dramatically.
A person would have to be exposed to that dose for 10 hours for it to be fatal, said Jae Moo-sung, a nuclear engineering expert at Seoul’s Hanyang University. Radiation elsewhere never reached that level.
In Tokyo, 170 miles to the southwest, authorities reported radiation levels nine times a normal level — too small, officials said, to threaten the 39 million people in and around the capital.
Weather patterns helped, shifting Tuesday night to the southeast, blowing any potential radiation from the plant toward the sea.
“It’s not good, but I don’t think it’s a disaster,” said Steve Crossley, an Australia-based radiation physicist. “If the radioactive material gets out, it’s a major problem. That doesn’t appear to be happening in Japan, and that’s the big difference. As long as you are not near it, it doesn’t pose a health risk.”
Though Kan and other officials urged calm, the developments fueled a growing panic in Japan and around the world amid widespread uncertainty over what would happen next.
In the worst case scenario, one or more of the reactor cores would completely melt down, a disaster that could spew large amounts of radioactivity into the atmosphere. The radiation fears added to the catastrophe that has been unfolding in Japan.
Four days after the 9.0-magnitude earthquake and tsunami, millions of people strung out along the east coast had little food, water or heat, and already chilly temperatures dropped further as a cold front moved in.
Up to 450,000 people are in temporary shelters. Officials have only confirmed about 3,300 deaths, but officials have said the toll was likely to top 10,000 in one of the four hardest-hit areas.
Experts involved in the 2004 Asian tsunami said there was no question more people died, despite Japan’s high state of preparation, and like the earlier disaster, many thousands may never be found.