Radiation Exposure Data for Nuclear Power Plant Workers (Fiscal Year 2012)

On October 9, 2013, the Nuclear Regulatory Agency published the FY2012 report on the management of worker radiation exposure at nuclear power facilities. www.nsr.go.jp/committee/kisei/data/0026_03.pdf  (in Japanese)

Table 1 shows the data on radiation dose management for workers in nuclear reactor buildings of nuclear power plants, based on the report’s data for “management of radioactive wastes and management of radiation doses of workers engaged in radiation-related jobs at nuclear reactor facilities for generating power for commercial use and those for generating power for research and development,” during the period from April 2012 through March 2013.

Previously, the data for Tokyo Electric Power Company’s (TEPCO) Fukushima Daiichi Nuclear Power Station and the Fukushima Daini Nuclear Power Station remained un-submitted, due to “a delay in dosage calculation by TEPCO’s subcontractors caused by the negative effects of the 2011 Great East Japan Earthquake.” The data was finally submitted on April 26, 2013.

Table 2 shows the revised report published on July 5. Earlier, the Ministry of Health, Labor and Welfare closely examined the internal exposure data in the original report in response to complaints from the World Health Organization and other international organizations about the data. As a result, the ministry discovered that there were a number of discrepancies between the data presented by TEPCO and those from its subcontractors. The revised July 5 report contains the re-calculations of the data.

The number of workers at the Fukushima Daiichi Nuclear Power Station who suffered a cumulative radiation exposure of 20 mSv annually totaled 738, consisting of 63 TEPCO employees and 675 subcontractor employees. The maximum annual radiation dose registered by workers stood at 54.1mSv.

Table 3 shows the distribution of annual radiation dose registered by the workers at the Fukushima Daiichi Nuclear Power Station each fiscal year, published by TEPCO. According to our calculations, the workers’ combined exposure doses for March 2011, FY2011, and FY2012 reached an enormously high level of approximately 341 man-Sv. Of these, about 73 percent are doses registered by subcontractor employees.

In most Western countries and South Korea, the central government has the responsibility for managing the radiation doses of workers at nuclear power facilities. In Japan, however, the subcontractors that employ such workers are expected to take responsibility for this. The government is doing nothing except collect the data from the subcontractors. Even after the nuclear accident in Fukushima on March 11, 2011, it is not TEPCO but the subcontractors who are required to manage worker radiation dose and worker health.It is still unclear how the major subcontractors evaluated the radiation doses of the workers employed by the lower and lowest level subcontractors.

Amid the confusion in the wake of the nuclear accident, there was a serious shortage of dosimeters for individual workers. Moreover, many workers lied about their doses, fearing that they might be fired once their doses exceeded the official limit. These incidents indicate that the published data do not correctly reflect the true situation on radiation doses. For many years, we have strongly insisted on the need for the government to unify the management of exposure doses of workers engaged in radiation-related work and take strict responsibility for data management. We called for the creation of such a system even before the March 11 nuclear accident, but the government has thus far totally failed to take the necessary measures.

(Mikiko Watanabe, CNIC)