Reference Material: Workers’ Exposure Data (FY2024)
By Tanimura Nobuko
CNIC has compiled a report below on radiation management at nuclear facilities*. The number of workers engaged in decommissioning efforts at Tokyo Electric Power’s (TEPCO’s) Fukushima Daiichi Nuclear Power Station came to about 12,000 in FY2024, unchanged from the previous fiscal year. The maximum radiation dose received was 16.8 millisieverts (mSv) and the collective effective dose was 24.73 person-sieverts. Difficulties encountered in retrieving fuel debris have led TEPCO to announce a delay in the schedule for starting full-scale retrieval work from early 2030 to 2037 or beyond. It is trying not to change its target for completing the reactor decommissioning work. The collective effective dose for workers involved in decommissioning measures has reached 196 person-sieverts as of the end of FY2024.
Decontamination work has continued since the nuclear accident in areas outside nuclear power station grounds that were contaminated. Even in 2024, 13 years after the accident, the number of workers involved in decontamination efforts outside the grounds exceeds 10,000 each year. Because it requires manual work under conditions of high radiation doses, exposure is unavoidable. Compared to the annual collective effective exposure of workers at nuclear power plants (NPPs), that of the off-site decontamination workers is considerably higher (see fig. below). The reality is evident that once a serious NPP accident occurs, an enormous amount of work involving radiation exposure will be necessitated over the long term both on and off site.
Fig. Comparison of annual collective effective dose for on-site work at NPPs and off-site decontamination
At other NPPs, too, worker exposures at the Takahama and Sendai nuclear power stations are high, followed by the Tokai Daini reactor, which is currently idled.
Regarding applications for worker’s compensation at the Fukushima Daiichi plant, three persons were announced as recognized in March 2024 and one in July 2025. To date, seven leukemia cases, one polycythemia vera case, two pharyngeal cancer cases, two thyroid cancer cases, two lung cancer cases and one colon cancer case have been recognized as workers’ injuries.** (During the translation of this article in October 2025, a further two persons were recognized as eligible for compensation as workers’ injuries (leukemia and colon cancer), bringing the total to 17 persons.)
*Searches through N-ADRES (Nuclear Regulation Authority’s archive search system) for “Report on Radiation Management for the send half of FY2024”: www.da.nra.go.jp/ (in Japanese)
** Ministry of Health, Labour and Welfare (2025) Regarding the results of examination and recognition of workers’ injuries by the Committee to Review Non-job-related aspects of Ionizing-radiation-related Disorders, 8 July 2025. www.mhlw.go.jp/content/11201000/001513132.pdf (in Japanese)
