By Toshihiro Okuyama | AjwAsahi
Nuclear plant workers not employed by the operating utilities were exposed to nearly four times the radiation doses received by utility employees, indicating that “outside workers” are often assigned the dangerous tasks, statistics showed.
In fiscal 2010, the accumulated dose total of all “outside workers,” who make up the bulk of the work force at nuclear plants in Japan, was about 30 times that of utility employees.
The figures were derived from annual reports the electric power companies submit to the Nuclear and Industrial Safety Agency about the radiation doses of workers–both their own employees and other workers–at nuclear power plants across Japan.
The other workers include contract workers hired by partner companies, such as equipment manufacturers and subcontractors.
According to the latest reports, 62,961 workers were engaged in radiation-related tasks in fiscal 2010 at nuclear power plants in Japan. (The figure does not include Tokyo Electric Power Co.’s Fukushima No. 1 and Fukushima No. 2 plants that were damaged by the Great East Japan Earthquake and tsunami on March 11, 2011.)
Overall, the workers were exposed to a dose of 1 millisievert on average, or a total of 61 sieverts for all workers.
But when broken down, the figures show that the 7,701 utility employees received an average radiation dose of 0.3 millisievert for an overall total of 2 sieverts. For the 55,260 “other workers,” or 88 percent of all workers, the average dose was 1.1 millisieverts for a total of 59 sieverts.
As the dose levels increased, the ratio of utility employees decreased. Utility employees accounted for 13 percent of all workers with doses up to 5 millisieverts, but that proportion plunged to 0.48 percent in the 5-10 millisievert bracket and 0.24 percent in the 10-15 millisievert range.
None of the 281 workers who were exposed to more than 15 millisieverts was a utility employee. The highest exposure level recorded was 19.6 millisieverts. Similar tendencies can be traced back to earlier years.
For example, in fiscal 2009, the 9,195 “other workers” at the Fukushima No. 1 nuclear plant were exposed to an average radiation dose of 1.5 millisieverts for a total of 14 sieverts. That far exceeded the average dose of 0.8 millisievert for the 1,108 TEPCO employees for a total of 0.85 sievert.
Only two of the 257 workers who were exposed to more than 10 millisieverts were TEPCO employees. The annual dose limit for male nuclear plant workers is 50 millisieverts during normal times. There have been no reports of figures exceeding that limit, which is considered safe against acute radiation syndrome.
There is, however, no consensus on the long-term effects of low-dose radiation exposure.
The average dose of TEPCO employees outstripped that of outside workers at the Fukushima No. 1 nuclear plant during the period between March 11, 2011, when the accident started, and May this year. That was because many TEPCO employees at the plant were exposed to high radiation doses.
But more than five times as many outside workers as TEPCO employees were exposed to radiation at the crippled plant.
© Copyright 2012 Asahi Shimbun and AJW - Published at Set You Free News with license