Two Tokyo Electric Power Co. employees working at the stricken Fukushima No. 1 nuclear plant may have been exposed beyond the 250-millisievert limit set for the crisis, Tepco and the government said Monday.
The two men, one in his 30s and the other in his 40s, have been at the plant since the March 11 disasters triggered the crisis. Both may have a cumulative exposure of several hundred millisieverts, a company official said, while adding the two are “not at a stage that would require emergency medical treatment.”
To cope with the country’s worst nuclear plant crisis, the government raised the legal limit on the amount of radiation a worker can be exposed to in emergencies to 250 milliseiverts from 100 millisieverts.
The National Institute of Radiological Sciences is expected to conduct a detailed assessment of the workers’ internal exposure to determine their total exposure, said Hidehiko Nishiyama, spokesman of the Nuclear and Industrial Safety Agency.
The two workers were involved in work at reactors 3 and 4. In a measurement on May 23, their thyroid glands were found to have absorbed 7,690 and 9,760 becquerels of radioactive iodine-131, respectively, 10 times more than other workers.
Their external exposure levels were between 74 and 89 millisieverts, Tepco said.
The two were working in the plant’s reactor control room, a building where the headquarters for the crisis is located, and outside in the compound.
They ingested stable iodine on March 13 to prevent radioactive iodine from accumulating in their thyroids and increasing their risk of thyroid cancer.
Tepco said it plans to check some 150 other workers who were engaged in similar work.
The utility is meanwhile coming to believe that it will be impossible to stabilize the crisis by the end of the year, senior company officials said Sunday. This could effect the evacuees’ chances of returning to their homes near the plant.
The recent confirmation that meltdowns had occurred in reactors 1 to 3 and probably breached the pressure vessels encasing the fuel, have led officials to believe “there will be a major delay to work” to contain the situation, one of them said, adding that they will try to close the breaches.
Tepco announced April 17 that its time line for bringing the troubled reactors into cold shutdown was six to nine months.
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