From Mainichi Shinbun English (5/30/2011; emphasis added):
TOKYO (Kyodo) -- Two Tokyo Electric Power Co. employees working at the crisis-hit Fukushima Daiichi nuclear power plant may have been exposed to radiation exceeding the ultimate limit of 250 millisieverts, but no health problems have so far been reported, the company and the government said Monday.
The two men, who are in their 30s and 40s and have been at the plant from the time the March 11 quake and tsunami triggered the crisis, may have been cumulatively exposed to several hundred millisieverts, a company official said, while adding that they are "not at a stage that would require emergency medical treatment."
The two workers have been involved in dealing with the plant's Nos. 3 and 4 reactors. At 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 higher than data on other workers.
The external exposure levels of the two workers were between 74 and 89 millisieverts, the plant operator known as TEPCO said.
The two have worked at the plant's reactor control room, a building where the headquarters to deal with the crisis is located, and outside on the premises. They ingested stable iodine on March 13 to prevent radioactive iodine from accumulating in the thyroid and increasing the risk of thyroid cancer.
TEPCO said it plans to check some 150 other workers who have engaged in similar work.
(The article continues.)
Well, what the article doesn't say (but it is mentioned in the Mainichi's Japanese articles) is that the two workers stopped taking potassium iodide pills after March 13. No reason is given. The Japanese articles also say that the high level of iodine-131 was detected from the urine of the workers.
These workers were not even working among highly radioactive debris outside or inside the turbine buildings or reactor buildings with high air radiation. They were working in the central control rooms for the Reactors 3 and 4, although the English article above makes it sound as if they were also working outside.
Did TEPCO have enough potassium iodide pills for the workers to begin with? Or the Japanese government?
The CBS News article back in March 16 alleges that the Japanese government had only 230,000 doses of potassium iodide when the Fukushima crisis started, and as of March 16 it hadn't yet asked other countries who had abundant supplies "at least not publicly". (h/t anon reader of my Japanese blog)
As far as the Japanese government went, it chose to hide the simulation data from the public that predicted the very high organ dose of iodine-131 over a surprisingly wide area rather than admitting the radiation problem and the lack of potassium iodide.