An explosion on March 15 damaged the containment structure of reactor No. 2 at the Fukushima Dai-ichi nuclear complex. Military fire trucks sprayed the reactor units at the complex in northeastern Japan in an attempt to cool them on March 18.
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Destroyed buildings are seen though the rubble in the northern town of Rikuzentakata on March 19.
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A woman cries amid the rubble in Rikuzentakata.
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Messages of the whereabouts of people who survived the tsunami cover the walls of the city hall in Kesennuma, Miyagi prefecture.
A member of a Japanese rescue team takes part in operations in Rikuzentakata.
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The operator of Japan's tsunami-damaged nuclear plant has backed away from plans for a tricky venting of radioactive gas at one of the troubled reactors, saying that pressure inside has stabilized.
Tokyo Electric Power company officials say the company has decided that there is no immediate need to vent the pressure at the Unit 3 reactor of the Fukushima Dai-ichi plant. They say the pressure is relatively high, but that it has stabilized.
Earlier Sunday, Japanese officials said pressure was rising in the reactor, and technicians prepared to vent radioactive gas into the air.
Growing concerns about radiation add to the overwhelming chain of disasters Japan has struggled with since the 9.0-magnitude quake. The March 11 quake spawned a tsunami that ravaged the northeastern coast, killing more than 8,100 people, leaving 12,000 people missing, and displacing another 452,000, who are living in shelters.
One piece of good news emerged early Sunday when rescuers found two survivors nine days after the disaster struck. An 80-year-old woman and her 16-year-old grandson were found inside their damaged home in northeast Japan. The area was rocked by the earthquake and decimated by the ensuing tsunami, but the two survivors were conscious and reported to be weak.
Traces of radiation are turning up well beyond the leaking Fukushima Dai-ichi plant after cooling systems to its six reactors were knocked out by the massive quake and tsunami. Radiation has seeped into the food supply, with spinach and milk from as far as 75 miles showing levels of iodine in excess of safety limits, although officials said they posed no immediate health hazard.
Minuscule amounts are being found in tap water in Tokyo and rainfall and dust over a wider area. Taiwan even reported receiving a batch of contaminated fava beans imported from Japan.
Government Admits Mistakes
Fuel, food and water remain scarce for a 10th day in the disaster. The government in recent days has acknowledged being caught ill-prepared by an enormous disaster that the prime minister has called the worst crisis since World War II and that required an immediate, full-scale response.
In the latest admission, a nuclear safety official said the government was caught off-guard by the accident's severity and only belatedly realized the need to give potassium iodide to those living within 12 miles of the nuclear complex.
The pills help reduce the chances of thyroid cancer, one of the diseases that may develop from radiation exposure. The official, Kazuma Yokota, said an explosion at the plant's Unit 3 reactor last Sunday should have triggered the distribution. But the order only came three days later.
"We should have made this decision and announced it sooner," Yokota told reporters at the emergency command center in the city of Fukushima. "It is true that we had not foreseen a disaster of these proportions. We had not practiced or trained for something this bad. We must admit that we were not fully prepared."
The Unit 3 Reactor
After the cascading troubles at the Fukushima plant appeared to lessen Saturday, pressure inside the vessel holding the reactor of Unit 3 rose again Sunday, dealing a setback to the government and forcing officials to consider the dangerous venting. Nuclear safety officials said one of the options could release a cloud dense with iodine as well as the radioactive elements krypton and xenon.
A Japanese rescue worker in Kesennuma, Miyagi prefecture, on Friday, one week after a massive earthquake and tsunami devastated northeastern Japan.
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Japanese troops unload food aid from a U.S. helicopter in Minamisanriku.
Dozens of coffins line a hall in Rifu, Miyagi prefecture. The official number of dead and missing has topped 16,600.
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Volunteers distribute rice balls at a shelter in Rikuzentakata, Iwate prefecture.
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A Japanese rescue worker transports an elderly survivor to a hospital in Kesennuma.
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A woman checks messages from survivors at a shelter in Sendai.
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A man looks at the stock price board in Tokyo. Japan's stocks posted solid gains Friday, and the yen relaxed after hitting historic highs, after the world's seven major industrial nations agreed to intervene in currency markets to help the earthquake-stricken nation.
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The plant's operator, Tokyo Electric Power Co., temporarily suspended the plans Sunday after the pressure inside the reactor stopped climbing, though it was at a relatively high level.
"It has stabilized," Tokyo Electric manager Hikaru Kuroda told reporters. Kuroda said temperatures inside the reactor reached 572 Fahrenheit and the option to release the highly radioactive gas inside — a maneuver he called a "dry vent" — is still under consideration if pressure rises.
The higher reactor pressure may have been caused by a tactic meant to reduce temperatures — the pumping of seawater into the vessel, Kuroda said.
Using seawater to douse Unit 3 and the plant's five other reactor vessels or their nuclear fuel storage pools was a desperate measure since it's corrosive, damaging the finely milled machine parts. The government acknowledged Sunday that the entire complex would be scrapped once the emergency is resolved.
"It is obviously clear that Fukushima Dai-ichi in no way will be in a condition to be restarted," Chief Cabinet Secretary Yukio Edano told reporters.
Meanwhile, the shelves in many food stores are bare. NPR's Jason Beaubien, reporting from northeastern Japan, says many stores on the main island have run out of noodles, bread and meat products, and entire milk coolers are empty.
Gasoline is also in short supply, as most gas stations remain shut. At the stations that remain open, there are long lines, and motorists are only allowed to buy roughly $12 worth of fuel at one time.
Electricity is returning, but water shortages persist in many of the hardest hit areas. Officials say more than a million people are still without running water.
Japanese officials said earlier that they had detected slightly elevated radiation levels in spinach and milk at farms in the area surrounding the Fukushima Dai-ichi nuclear complex, and that trace amounts of radioactive iodine had been found some 150 miles south of the plant, in the capital Tokyo.
Edano insisted that the radiation found in the spinach and milk "pose no immediate health risk." Separately, the Health Ministry said the iodine in the water did not exceed government safety limits.
From corner stores to Tokyo's vast Tsukiji fish market, Japanese shoppers picked groceries with care Sunday after the discovery of contamination in spinach and milk fanned fears about the safety of this crowded country's food supply.
"It's a little hard to say this, but I won't buy vegetables from Fukushima and that area," said Yukihiro Sato, 75, shopping at a bustling Tokyo supermarket.
NPR Science Correspondent Christopher Joyce said news of the contaminated food was "unsettling, and obviously people are concerned about this because it goes to human health, but it's not unexpected."
"The levels are really low," he said. "Authorities say eating the tainted food would give a dose less than a cat scan at a hospital, though they didn't make it clear how much or how long you'd have to eat the spinach."
Farmers and merchants expressed fears of their own that public anxiety might hurt even producers of goods that were free of contamination.
"There will probably be damaging rumors," said farmer Shizuko Kohata, 60, who was evacuated from the town of Futaba, near the Fukushima complex, to a sports arena in Saitama, north of Tokyo.
"I grow things and I'm worried about whether I can make it in the future," Kohata said Saturday.
On Sunday, an official in Taiwan told The Associated Press that radiation was detected on fava beans imported from Japan in what appears to be the first case of contamination in Japanese imports.
The amount of radiation was well below Taiwan's legal limit and not harmful to human health, the official from Taiwan's Cabinet-level Atomic Energy Council said, speaking on condition of anonymity because he was not authorized to deal with the press. The precise amount and type of radiation were not disclosed.
Japan's food exports are worth about $3.3 billion a year — less than 0.5 percent of its total exports — and seafood makes up 45 percent of that, according to government data.
Official Says Backup Power Systems Were Vulnerable
The failure of Fukushima's backup power systems — which were supposed to keep cooling systems going in the aftermath of the magnitude 9.0 quake and resultant tsunami — let fuel overheat and were a "main cause" of the crisis, Nishiyama said.
He said the backup power systems had been improperly protected, leaving them vulnerable to the twin natural disasters that set off the nuclear emergency.
"I cannot say whether it was a human error, but we should examine the case closely," Nishiyama told reporters Saturday.
TEPCO spokesman Motoyasu Tamaki said that while the generators themselves were not directly exposed to the waves, some of the electrical support equipment was outside. He said the complex was designed to protect against tsunamis of up to 16 feet. Media reports say the tsunami was at least 20 feet high when it struck Fukushima.
Tamaki also acknowledged that the complex was old, and might not have been as well-equipped as newer facilities.
On Saturday, emergency workers at Fukushima Dai-ichi used water cannons for a third day to hose down overheating spent fuel rods.
NPR's Joyce said they had succeeded in getting at least some water into a spent fuel pool at reactor No. 3, where a hydrogen explosion Monday blew the roof off the building.
Workers set up a big tanker truck they're calling "super pumper" next to one of the damaged reactors. The truck is connected to a hose that extends a quarter mile to draw sea-water in. The 13-hour operation ended in the early morning hours Sunday.
Holes were also punched in the roofs of units 5 and 6 to vent buildups of hydrogen gas, and the temperature in unit 5's fuel storage pool dropped after new water was pumped in, according to TEPCO officials.
More workers were thrown into the effort — bringing the total at the complex to 500 — and the safety threshold for their radiation exposure was raised 2.5 times so they could keep working.
Officials insisted that would cause no health damage.
The unfolding crises have led to power shortages in Japan, forced factories to close, sent shockwaves through global manufacturing and triggered a plunge in Japanese stock prices.
Most of Japan's auto industry is shut down. Factories from Louisiana to Thailand are low on Japanese-made parts. Idled plants are costing companies hundreds of millions of dollars. And U.S. car dealers may not get the cars they order this spring.
Japan acknowledged Friday that the enormity of the natural disasters overwhelmed the government. It also raised the severity rating of the disaster at the Fukushima plant from Level 4 to Level 5 on the seven-level International Nuclear Event Scale. That puts the crisis on a par with the Three Mile Island accident in Pennsylvania in 1979, but still below the1986 Chernobyl accident, which killed at least 31 people with radiation sickness and ranked a Level 7.
Cabinet Secretary Edano said Friday that Tokyo has asked Washington for help and that the two allies were discussing specifics.
"We are coordinating with the U.S. government as to what the U.S. can provide and what people really need," he said.
Experts from the U.S. Department of Energy and the Nuclear Regulatory Commission are currently in Japan. The U.S. also is sending specialized aircraft to help determine the scope of the nuclear contamination. The converted Boeing C-135 plane, called Constant Phoenix or "the Sniffer," will fly over Japan's nuclear plants and take samples from the atmosphere. Another Air Force plane, a drone called Global Hawk, is already circling above the plants. Its infrared sensors can detect heat and help determine the effectiveness of attempts to cool the reactors.
Low levels of radiation have been detected well beyond Tokyo, which is 140 miles south of the plant, but hazardous levels have been limited to the plant itself. Still, the crisis has forced thousands to evacuate their homes and drained Tokyo's normally vibrant streets of life, its residents either leaving town or holing up indoors.
The U.S. military, which has 50,000 troops based in Japan, was working to ramp up its relief effort. But snow has limited helicopter flights and American aircraft are under orders to skirt the area around the nuclear plant to reduce the risk of radiation exposure.
In a statement Friday, the U.S. 7th Fleet said 12,750 of its personnel were involved in the relief effort, dubbed Operation Tomodachi, along with 20 ships led by the aircraft carrier USS Ronald Reagan and 140 aircraft.
With reporting from NPR's Russell Lewis, Christopher Joyce and Richard Harris in Tokyo and Tom Bowman in Washington, D.C. Material from The Associated Press was used in this story.