TEPCO skews employee radiation exposures lower by insisting on calculating from March 21 - Nine full days after the hydrogen explosion in Dai-ichi

Gov't calls TEPCO radiation exposure standards 'overly optimistic'

"As the number of workers exposed to high levels of radiation at the crippled Fukushima No. 1 Nuclear Power Plant increases, the government is accusing plant operator Tokyo Electric Power Co. (TEPCO) of slack radiation dose calculations.

"From the start, the way TEPCO calculates internal radiation exposure has been overly optimistic," a senior Ministry of Health, Labor and Welfare official stated.

On June 14, Health, Labor and Welfare Minister Ritsuo Hosokawa directed TEPCO to withdraw any worker exposed to more than 100 millisieverts of internal radiation at the disaster-stricken plant, sparking a dispute between the company and the government over radiation dose calculation standards, and delaying the implementation of worker safety-first policies at the plant.

Meanwhile, with work at the Fukushima plant -- where three reactors have melted down -- projected to go on for some time, uncertainty over exactly how high a dose workers there are subjected to may impact TEPCO's public timetable for resolving the nuclear crisis.

On May 30, TEPCO revealed that two of its Fukushima No. 1 plant workers had been exposed to a higher radiation dose than the 250 millisievert emergency upper limit, though the firm did not state how much of that exposure had been from radioactive materials taken into the body.

The labor ministry had demanded that TEPCO calculate workers' cumulative radiation exposure starting from March 12, when a hydrogen explosion destroyed the plant's No. 1 reactor building. However, TEPCO rejected the government demand, stating, "It's impossible to say when any internal radiation exposure occurred. If workers were on the job until the end of March, then cumulative radiation calculations should be made starting March 21, about half way between the day of the earthquake and the end of the month."

Internal radiation doses are measured with a device called a "whole body counter," which measures not only current exposure but sums up a person's total dose over time. As such, TEPCO's insistence on calculating total radiation doses starting from March 21 has resulted in significantly lower exposure figures than those the government is using.

"We tried to persuade TEPCO to use a rigorous calculation method but the company wouldn't give in. In fact we're still at odds over the issue," the labor ministry's standards bureau told the Mainichi.

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