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A stranded elderly woman is carried on the back of a Japanese soldier after being rescued from a residence at Kesennuma, northeastern Japan, on Saturday.
AP PHOTO
Volunteer firefighters search for victims at Rikuzentakada, Iwate Prefecture, northern Japan, Sunday.
AP PHOTO
A rider passes by an overturned fishing boat which was washed away by tsunami, in Hachinohe, Aomori, northern Japan Sunday.
AP PHOTO
A woman embraces her grandchild as they were reunited at a shelter in Natori, Miyagi, northern Japan Saturday following Friday’s catastrophic earthquake and tsunami.
AP PHOTOS
IWAKI, Japan — Cooling systems failed at another nuclear reactor on Japan’s devastated coast Sunday, hours after an explosion at a nearby unit made leaking radiation, or even outright meltdown, the central threat to the country following a catastrophic earthquake and tsunami.
Japan’s top government spokesman says a partial meltdown likely is under way at a second reactor and that radiation at the nuclear plant briefly rose above legal limit. He said fuels rods were briefly exposed at that reactor.
The Japanese government initially said radiation emanating from the plant appeared to have decreased after Saturday’s blast, which produced a cloud of white smoke that obscured the complex. But the danger was grave enough that officials pumped seawater into the reactor to avoid disaster and moved 170,000 people from the area.
Japan’s nuclear safety agency then reported an emergency at another reactor unit, the third in the complex to have its cooling systems malfunction. To try to release pressure from the overheating reactor, authorities released steam that likely contained small amounts of radiation, the government said.
Japan dealt with the nuclear threat as it struggled to determine the scope of the earthquake, the most powerful in its recorded history, and the tsunami that ravaged its northeast Friday with breathtaking speed and power. The official count of the dead was 763, but the government said the figure could far exceed 1,000.
Teams searched for the missing along hundreds of miles (kilometers) of the Japanese coast, and thousands of hungry survivors huddled in darkened emergency centers that were cut off from rescuers and aid. At least a million households had gone without water since the quake struck. Large areas of the countryside were surrounded by water and unreachable. Some 2.5 million households were without electricity.
Powerful aftershocks continued to rock the country, including one Sunday with a magnitude of 6.2 that originated in the sea, about 111 miles (179 kilometers) east of Tokyo. It swayed buildings in the capital, but there were no reports of injuries or damage.
The explosion at the nuclear plant, Fukushima Dai-ichi, 170 miles (274 kilometers) northeast of Tokyo, appeared to be a consequence of steps taken to prevent a meltdown after the quake and tsunami knocked out power to the plant, crippling the system used to cool fuel rods there.
The blast destroyed the building housing the reactor, but not the reactor itself, which is enveloped by stainless steel 6 inches (15 centimeters) thick.
Inside that superheated steel vessel, water being poured over the fuel rods to cool them formed hydrogen. When officials released some of the hydrogen gas to relieve pressure inside the reactor, the hydrogen apparently reacted with oxygen, either in the air or the cooling water, and caused the explosion.
“They are working furiously to find a solution to cool the core,” said Mark Hibbs, a senior associate at the Nuclear Policy Program for the Carnegie Endowment for International Peace.
Nuclear agency officials said Japan was injecting seawater into the core — an indication, Hibbs said, of “how serious the problem is and how the Japanese had to resort to unusual and improvised solutions to cool the reactor core.”
Officials declined to say what the temperature was inside the troubled reactor, Unit 1. At 2,200 degrees Fahrenheit (1,200 degrees Celsius), the zirconium casings of the fuel rods can react with the cooling water and create hydrogen. At 4,000 Fahrenheit (2,200 Celsius), the uranium fuel pellets inside the rods start to melt, the beginning of a meltdown.
Chief Cabinet Secretary Yukio Edano said radiation around the plant had fallen, not risen, after the blast but did not offer an explanation. Virtually any increase in dispersed radiation can raise the risk of cancer, and authorities were planning to distribute iodine, which helps protect against thyroid cancer. Authorities ordered 210,000 people out of the area within 12 miles (20 kilometers) of the reactor.
Among those waiting to leave was Reiko Takagi, a middle-aged woman standing outside a taxi company in Iwaki, about 19 miles (30 kilometers) from the nuclear plant.
“Everyone wants to get out of the town. But the roads are terrible,” Takagi said. “It is too dangerous to go anywhere. But we are afraid that winds may change and bring radiation toward us.”
Officials have said that radiation levels at Fukushima were elevated before the blast: At one point, the plant was releasing each hour the amount of radiation a person normally absorbs from the environment each year.
The Japanese utility that runs the plant said four workers suffered fractures and bruises and were being treated at a hospital. Nine residents of a town near the plant who later evacuated the area tested positive for radiation exposure, though officials said they showed no health problems.
Two days after the magnitude 8.9 quake, there were grim signs that the death toll could soar. One report said no one could find four whole trains. Others said 9,500 people in one coastal town were unaccounted for and that at least 200 bodies had washed ashore elsewhere.
The government said 642 people were missing and 1,426 injured.
Atsushi Ito, an official in Miyagi prefecture, among the worst-hit states, could not confirm the figures, noting that with so little access to the area, thousands of people in scores of towns could not yet be reached.
MORE INSIDE
For more coverage on the devastation in Japan, see Pages 8A, 9A, 10A