The operator of Japan's tsunami-damaged nuclear plant on Sunday 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 said the company decided that there was no immediate need to vent the pressure at the Unit 3 reactor of the Fukushima Dai-ichi plant. They said the pressure is relatively high, but that it has stabilized.
Meanwhile, the government warned that tests of spinach and milk from areas as far as 75 miles away exceeded safety limits. Tap water farther away turned up tiny amounts of radioactive iodine in Tokyo and other areas.
Food beyond Japan's borders was also reportedly tainted. Radiation was detected on fava beans imported from Japan to Taiwan, Taiwanese officials said in what appears to be the first case of contamination in Japanese imports.
Taiwan's Cabinet-level Atomic Energy Council Radiation Monitoring Center said in a statement that a small amount of iodine and cesium had been found on a batch of Japanese fava beans imported to the island on Friday. The center said 11 becquerels of iodine and 1 becquerel of cesium were detected.
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The amount of radiation was well below Taiwan's legal limit and not harmful to human health, an official from the center told The Associated Press.
The official spoke on condition of anonymity because he was not authorized to deal with the media.
Amid concerns of wider contamination, 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 Fukushima Dai-ichi 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."
While four of Fukushima's six nuclear reactors have been dangerously overheating since the March 11 earthquake and tsunami disrupted cooling systems, Unit 3 has proved particularly troublesome.
After the government said Saturday that the unit appeared to be stabilizing after being doused with water, nuclear safety officials said the efforts may not have worked. Pressure was rising on Saturday inside the reactor's containment vessel, requiring a release of radioactive gas to prevent a more dangerous buildup, said safety agency official Hidehiko Nishiyama.
While battling Unit 3, emergency teams used an unmanned vehicle to spray water at another at-risk reactor — Unit 4 — while preparing to switch power back on for the first time since a March 11 earthquake and tsunami knocked out the plant's crucial cooling systems.
However, there was no guarantee the cooling systems would still work, even once power was restored.
Minuscule amounts of radioactive iodine were found in tap water Friday in Tokyo and elsewhere in Japan — although experts said none of those tests showed any health risks. They also said radioactive dust and particles found in Greater Tokyo area also posed no risk to human health.
The Health Ministry also said that radioactive iodine slightly above government safety limits was found in drinking water at one point Thursday in a sampling from Fukushima prefecture, the site of the nuclear plant, but later tests showed the level had fallen again.
Six workers trying to bring the Fukushima Dai-ichi plant back under control were exposed to more than 100 millisieverts of radiation — Japan's normal limit for those involved in emergency operations, according to Tokyo Electric Power Co., which operates the complex. The government raised that limit to 250 millisieverts on Tuesday as the crisis escalated.
"We more or less do not expect to see anything worse than what we are seeing now," Hidehiko Nishiyama of the Nuclear and Industrial Safety Agency said earlier.
Japan has been grappling with a cascade of disasters unleashed by the 9.0-magnitude earthquake on March 11. The quake spawned a tsunami that ravaged Japan's northeastern coast, killing more than 8,100 people and knocking out cooling systems at the Fukushima Dai-ichi nuclear plant, causing the complex to leak radiation.
More than 12,000 people are still missing, and more than 452,000 are living in shelters. The quake and tsunami has likely killed more than 15,000 people in Miyagi prefecture alone, Kyodo news agency said Sunday, quoting local police.
'No immediate health risk'
Chief Cabinet Secretary Yukio Edano, meanwhile, insisted the contaminated foods "pose no immediate health risk."
The tainted milk was found 20 miles from the plant, a local official said. The spinach was collected from six farms between 60 miles and 75 miles to the south of the reactors.
Those areas are rich farm country known for melons, rice and peaches, so the contamination could affect food supplies for large parts of Japan.
More tests were being done on other foods, Edano said, and if they show further contamination, then food shipments from the area would be halted.
Disaster at a glance
Officials said it was too early to know if the nuclear crisis caused the contamination, but Edano said air sampling done near the dairy showed higher-than-normal radiation levels.
Iodine levels in the spinach exceeded safety limits by three to seven times, a food safety official said. Tests on the milk done Wednesday detected small amounts of iodine-131 and cesium-137, the latter being a longer-lasting element that can cause more types of cancer. But only iodine was detected Thursday and Friday, a Health Ministry official said.
Calming a jittery public
After the announcements, Japanese officials immediately tried to calm an already-jittery public, saying the amounts detected were so small that people would have to consume unimaginable amounts to endanger their health.
"Can you imagine eating one kilogram of spinach every day for one year?" said State Secretary of Health Minister Yoko Komiyama. One kilogram is a little over two pounds.
Edano said someone drinking the tainted milk for one year would consume as much radiation as in a CT scan; for the spinach, it would be one-fifth of a CT scan. A CT scan is a compressed series of X-rays used for medical tests.
The Health Ministry said iodine levels slightly above the safety limit were discovered Thursday in drinking water samples from Fukushima prefecture. On Friday, levels were about half that benchmark; by Saturday, they had fallen further.
Drinking one liter of water with the iodine at Thursday's levels is the equivalent of receiving one-eighty-eighth of the radiation from a chest X-ray, said Kazuma Yokota, a spokesman for the prefecture's disaster response headquarters.
The trace amounts of iodine were found in Tokyo's water on Friday, the first day since the government ordered nationwide daily sampling due to the nuclear crisis, the Ministry of Education, Culture, Sports, Science and Technology said. A ministry statement said the amounts found did not exceed government safety limits. But tests on water, which for decades were only done once a year, usually show no iodine.
At the Fukushima plant, emergency workers have been struggling to cool the reactors and the pools used to store used nuclear fuel, as well as to put the facility back on the electricity grid.
A replacement power line reached the complex Friday, but workers needed to methodically work through badly damaged and deeply complex electrical systems to make the final linkups without setting off a spark and potentially an explosion. Company officials hoped to be able to switch on the cooling systems Sunday.
Quake risk at nuclear plants
Once the power is reconnected, it is not clear if the cooling systems will still work.
A fire truck with a high-pressure cannon pumped water directly from the ocean into one of the most troubled areas of the complex — the cooling pool for used fuel rods at the plant's Unit 3. Because of high radiation levels, firefighters only went to the truck every three hours to refuel it.
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 officials with Tokyo Electric Power Co., which owns the complex.
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 2½ times so they could keep working.
Officials insisted that would cause no health damage.
The Associated Press and Reuters contributed to this report.