At a store in Misaki, Chiba provice, a sign says milk products are not being… (Everett Kennedy Brown /…)
Reporting from Tokyo and Los Angeles — Japanese and U.S. officials gave additional indications of progress in efforts to stabilize the Fukushima nuclear plant, but the list of tainted agricultural products grew Monday to include canola and chrysanthemum greens, a day after milk and spinach showed traces of radioactive isotopes.
The food samples were taken from areas as far as 43 miles from the Fukushima Daiichi nuclear plant, Japanese officials said, and some registered nearly seven times the allowable levels of the radioactive isotope iodine-131, a hazardous byproduct of nuclear fission that can cause thyroid cancer. Taiwan also said it discovered small amounts of radiation in fava beans from Japan, as foreign governments appeared to be stepping up inspections of Japanese food imports.
The Japanese government emphasized that the contamination levels were not immediately harmful to humans. Nonetheless, Japanese authorities seeking to reassure a nervous public and protect the nation's food exports and reputation said that none of the vegetables in question had been shipped to market. A spokesman said the government would decide Monday whether to place a ban on shipments of spinach and milk produced in certain areas, which contained excessive amounts of iodine-131 and cesium-137.
Photos: Unrelenting crisis grips Japan
The government also said it had found higher-than-average levels of radioactive materials in the air and tap water in Tokyo and elsewhere in Japan. Those levels pose no threat to human health, officials said, but as a precaution, people were urged to avoid getting wet by rain. Showers were forecast for Monday in the area where the Fukushima nuclear plant is located, about 150 miles north of Tokyo.
Japan's Nuclear and Industrial Safety Agency said it had begun testing samples from the ocean near the plant for radioactivity, amid fears that contamination will also be seen in fish.
Radiation measurements at the Fukushima plant are still high, but a senior U.S. nuclear official said Sunday that they may be tapering off.
The plant, which houses six nuclear reactors, showed radiation levels in the range of hundreds of millisieverts per hour, said Gregory Jaczko, chairman of the U.S. Nuclear Regulatory Commission. The duration of those readings was not clear. The exposure limit for Japanese workers was recently raised to 250 millisieverts per year.
The average American is exposed to 6.2 millisieverts of radiation per year, half of which come from natural sources, according to the commission.
The Nuclear Regulatory Commission is using "a variety of sources," including data from the Department of Energy, to assess radiation levels at the Fukushima plant and in the surrounding area, Jaczko said on the C-SPAN program "Newsmakers." But power interruptions at the plant have knocked out some of the instruments that would normally provide reliable readings.
In Tokyo, Tetsuro Fukuyama, the deputy chief Cabinet secretary, said Sunday that officials were "getting closer to bringing the situation under control."
The increased hopes came after the Tokyo Electric Power Co. indicated it had made progress in restoring electrical power to the facility to restart cooling systems knocked out by the March 11 earthquake and tsunami. Government officials said power was extended to the No. 2 and No. 5 reactors Sunday afternoon.
Some American scientists were more cautious about assessing the progress. Although the restoration of electricity to two of the reactors at the Fukushima plant appears to have stabilized them, the situation in "is still quite uncertain," said Edwin Lyman of the Union of Concerned Scientists in Washington.
"It's premature to make any assessment about the most severely affected reactors," he said.
Damage already incurred by the nuclear fuel rods in the plant's other four reactors may make it more difficult for workers to cool them to a safe temperature, even after electricity is fully restored, Lyman said.
Japanese officials said there were signs of progress in their ongoing efforts to cool overheated spent-fuel rods in tanks by dousing them with tons of cold seawater. Defense Minister Toshimi Kitazawa said that the temperatures of the pools holding depleted fuel at all six reactor units were below the boiling point of water. But a temporary rise in pressure in the No. 3 reactor on Sunday indicated the still-volatile nature of the efforts to contain the disaster, which has included explosions and fires at three of the reactors in the power complex.
The crisis began when the earthquake caused reactors Nos. 1, 2 and 3 to shut down, power from the grid was lost, and backup diesel pumps were hobbled by the tsunami. Reactor Nos. 4, 5, and 6 had been shut for maintenance but still require circulating water to cool their radioactive cores and depleted-fuel pools.