Worker Exposure Data
On August 20 the Nuclear Industrial and Safety Agency released data relating to worker radiation exposure and the management of radioactive waste at nuclear facilities for the 2006 fiscal year.
At nuclear power plants in FY2006 a total of 66,895 workers (8,632 electric utility workers and 58,343 subcontractor workers - people who worked at more than one plant are double-counted) received a collective dose of 67.43 person-sieverts (3.28 person-sieverts for utility workers and 64.14 person-sieverts for subcontractor workers). The average individual dose of 1.0 milli-sieverts (0.4 mSv for utility wokers and 1.1 mSv for subcontractor workers) was the same as the previous year. Over 95% of the total dose was received by subcontractor workers. The highest individual dose for a utility worker (12.9 mSv) was received by a worker at the Fukushima I plant, while the highest individual dose for a subcontractor worker (19.7 mSv) was received by a worker at the Ohi plant.
In Japan, exposure is greatest for people who work for subcontractors. Moreover, these people often work at more than one nuclear power plant. In 1977 the Radiation Dose Registration Center was established for the purpose of accurately and consistently assessing and managing the dose of individual workers. It was established within the Radiation Effects Association, which is financed and managed by the electric utilities. It began recording data in 1980 and publishes the total yearly radiation dose and the number of related work places for each radiation industry worker.
According to the 2006 report, 25% of workers worked at two or more places. The average dose of people who worked at only one place was 0.7 mSv. The table below shows a strong trend for radiation dose to increase as people work at more places.
Relation between number of radiation-related
work places and radiation dose
|Number of work places
|Average radiation dose (mSv)
Workers' Compensation Case of the Late Tadashi Kiyuna
Tadashi Kiyuna worked at nuclear power plants all around Japan, mainly at Pressurized Water Reactors, including Tomari, Ikata, Mihama, Ohi, Tsuruga and Genkai. He also worked at the Rokkasho Reprocessing Plant. His job was to check for radiation leaks. His total dose in just over six years from September 1997 to January 2004 was assessed to have been 99.76 mSv. He was a victim of the push to reduce costs through longer consecutive operation of nuclear power plants and shorter periodic inspections. His health got progressively worse until he was forced to quit in February 2004. In May that year he was diagnosed as having malignant lymphoma, a form of blood cancer. He died after great suffering in March the following year at the age of 53.
In October 2005 his family applied to the Yodogawa Labor Standard Supervision Office in Osaka for worker's compensation. The application was rejected in September 2006, without a sample being submitted for assessment by the central office, on the grounds that there is no precedent for accepting malignant lymphoma. Kiyuna's family appealed in October and the case is still being assessed. On June 8 this year, in the context of negotiations with the government over several radiation exposure issues, the Ministry of Health, Labour and Welfare agreed to reconsider Kiyuna's application for worker's compensation. Now the stage is set for the real negotiations to begin.
In Japan, approval of radiation-related workers' compensation for nuclear workers has been based on very narrow criteria. Until now, with the exception of Mitsuaki Nagao's multiple myeloma (see NIT 99), the only cases that have been accepted have been for leukemia. It would be a great step forward for workers' compensation for Japan's nuclear workers if Kiyuna's malignant lymphoma were to be accepted.