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Level of radioactive iodine in Tokyo water supply falls

Three workers suffer burns at crippled plant

Officials distributed bottled water for an estimated 80,000 children under the age of 1 in the Tokyo area yesterday. Officials distributed bottled water for an estimated 80,000 children under the age of 1 in the Tokyo area yesterday. (Kyodo New via Associated Press)
By David Jolly
New York Times / March 25, 2011

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TOKYO — Levels of a radioactive isotope found in Tokyo’s water supply fell by more than half yesterday, testing below the country’s stringent maximum for infants, even as three workers at the stricken nuclear plant to the north suffered radiation burns as they struggled to make emergency repairs.

The lowered readings in Tokyo’s water came hours after Yukio Edano, the chief Cabinet secretary, said the isotope, iodine 131, had been detected in the water supply of Kawaguchi City, just north of Tokyo, as well as those of two of Tokyo’s neighboring prefectures, Chiba and Saitama. On Wednesday, authorities cautioned those in the affected area not to give infants tap water.

The problem is not likely to end soon; nuclear workers will have to keep venting radioactive gases from the damaged reactors, adding to the plume of emissions carried by winds and dispersed by rain. The public has already been warned not to consume food and milk from the immediate area.

“Continued monitoring of the situation is essential,’’ a Tokyo government statement said.

Edano said the three injured workers had radiation burns on their legs after dragging an electrical cable through contaminated water in an effort to restore a crucial pump at Reactor No. 3 in the Fukushima Daiichi nuclear plant. The workers were burned as contaminated water poured over the tops of their low boots, soaking their feet and ankles, The Asahi Shimbun newspaper reported, citing sources with Tokyo Electric Power, the plant’s operator.

Two workers were taken to Fukushima Medical University Hospital and were expected to be transferred to the National Institute of Radiological Sciences in Chiba City. Edano did not elaborate on the status of the third worker. Hiro Hasegawa, a Tokyo Electric spokesman, said that the third man had not been hospitalized but that he could not comment further.

The three were employed by a subcontractor of Tokyo Electric, Edano said, and were trying to connect a cable in the basement of the turbine building next to the No. 3 reactor. They were exposed to more than 170 millisieverts of radiation, he said. That is more than the old maximum of 100 millisieverts for workers but less than the new maximum of 250 millisieverts instituted in the days after the disaster. The injuries would appear to raise questions about whether the new maximum is too high.

Halting progress was reported in the efforts to restart the plant’s cooling systems that were knocked out in the earthquake and tsunami March 11.

An official at Tokyo Electric said workers had restored lighting in the central control room of Reactor No. 1, an important step toward restarting its cooling system. The temperature in the reactor pressure vessel has been showing a worrisome increase, and Edano said efforts were being focused on resolving the problem.

Officials of Japan’s Nuclear and Industrial Safety Agency said that Reactors No. 1 and No. 4 were giving off white smoke but that it was not interrupting repair work.

The warning Wednesday over the heightened levels of iodine 131, which can accumulate in the thyroid and cause cancer, set off widespread anxiety and a run on bottled water emptied store shelves in Tokyo. Yesterday morning, the authorities were distributing water for the estimated 80,000 children less than 1 year old in the area and considering importing bottled water. The authorities said frequent rains might have washed radiation into Tokyo’s watershed, which lies mostly north and northeast of the city.

Emissions from the plant have largely blown east; elevated levels of iodine 131 and another dangerous isotope, cesium 137, were found 18 miles off the coast, according to the International Atomic Energy Agency.

Japan’s limits on iodine 131 are far lower than those of the international agency, and are measured in units called becquerels. Japan says older children and adults should get no more than 300 becquerels per liter; the agency recommends a limit of 3,000 becquerels.

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