Despite alarming new radiation data presented by the International Atomic Energy Agency, the government said Thursday it has no plans to widen the evacuation zone around the crippled Fukushima No. 1 power plant.
The international nuclear watchdog said Wednesday in Geneva it detected about 2 million becquerels of radioactive substances per sq. meter, or double the threshold at which the IAEA itself would order an evacuation, in soil samples from the village of Iitate about 40 km northwest of the nuclear power plant.
With the data, the IAEA effectively urged Japan to expand the current no-go zone of 20 km around the plant. Residents in areas 20 km to 30 km of the plant have been advised to stay indoors.
Chief Cabinet Secretary Yukio Edano only said the government may consider expanding the mandatory evacuation zone if the higher levels of radiation continue.
“If a person is exposed to the radiation levels exceeding the IAEA criteria for a long time, it might affect their health because radioactive substances could accumulate in the body,” Edano said. “If that is the case, we need to consider evacuating residents from the area.”
But for now, he said, the government will conduct air and soil monitoring in a more detailed manner at Iitate, where about 100 people still reside.
Edano’s apparent attempt to play down the alarm bells rung by the IAEA was offset by the rising radioactivity detected from seawater near the plant.
The Nuclear and Industrial Safety Agency said Thursday the level of radioactive iodine-131 in seawater near the plant was 4,385 times the maximum tolerable amount, the highest reading since the crisis began March 11.
Other highly radioactive materials were also detected, including cesium-134 at 783.7 times the maximum amount permitted, and cesium-137 at 527.4 times the legal limit.
The half-life of cesium-137, or the time its radioactivity dissipates by half, is 30 years compared with eight days for iodine-131 and two years for cesium-134.
The radiation level in seawater near the plant has been renewing record figures since last week.
The NISA stressed again that the amount doesn’t pose an immediate health risk to people in the area.
“Although the figure is on the rise, it will not immediately affect (the health) of residents nearby as the evacuation area is set at a 20-km radius from the nuclear plant and fishermen are not working in the area,” said agency official Hidehiko Nishiyama. “Radioactive material will spread and dilute by the time people take it in through marine products.”
But Nishiyama also said the NISA will increase the number of ocean monitoring sites. The science ministry has been monitoring radiation about 30 km offshore while the NISA will conduct checks about 15 km from the coast.
Meanwhile, work to remove toxic water at the plant continued as Tokyo Electric Power Co. began pumping out a nearly full trench below reactor No. 1′s turbine building, the NISA said.
After pumping out water from about 9 to 11:30 a.m., the level decreased by 1 meter, the agency said. The water was moved to a storage tank near reactor No. 4.
It was confirmed over the weekend that trenches below the turbine buildings of reactors 1, 2 and 3 were filled with water.
It is not known where the toxic water came from, and the water in unit No. 2′s trench contains high levels of radiation — more than 1,000 millisieverts per hour — according to Tepco.
Tepco is also working to remove contaminated water in the basements of the turbine buildings for all four reactors. The depth of the flooding ranges from 20 cm to 1.5 meters.
Tepco hopes to pump out the contaminated water so new water can be pumped in to cool the crippled reactors, but it is facing a tough challenge relaying spilled toxic water from one tank to another.
Media reports Thursday said the government is considering building a facility to store and properly dispose of the contaminated water. According to the Tokyo Shimbun, the government has already asked a general contractor to work on the problem.
But Hidehiko Nishiyama of the NISA said he had not heard such a decision had been made, while admitting it was possible.
On Thursday, bad weather forced Tepco to cancel a plan to spray synthetic resin on the plant premises to prevent the further spread of radiation.
Information from Kyodo added