Cleanup crews around the crippled Fukushima No. 1 nuclear power plant were exposed to an average dose of 0.5 millisievert of radiation per year, well below the government safety standard, a report shows.
Cleanup crews around the crippled Fukushima No. 1 nuclear power plant were exposed to an average dose of 0.5 millisievert of radiation per year, well below the government safety standard, a report shows.
Released April 15 by the government-affiliated Radiation Effects Association, the report said the maximum dose for decontamination workers was 13.9 millisieverts per year, while the average dose was half the mean exposure level for ordinary nuclear plant workers of 1 millisievert.
Decontamination work is currently under way in broad areas near the Fukushima plant, which experienced a triple meltdown in the 2011 earthquake and tsunami disaster.
The association surveyed individuals who had been involved in state-led decontamination work between 2011 and 2013.
According to the report, no cleanup workers exceeded the health ministry's annual exposure limit of 50 millisieverts during the study period.
The report said 11,058 individuals were engaged in decontamination work around the Fukushima plant in 2011 and 2012. The highest exposure level of 13.9 millisieverts was detected during the period for one worker, with the average radiation dose being 0.5 millisievert.
In 2013, 20,564 people were engaged in the cleanup work and were exposed to a maximum radiation level of 6.7 millisieverts. The average exposure for 2013 was 0.5 millisievert per year.
The association also released preliminary readings for each quarter.
According to the data, cleanup crews received an average radiation dose of 0.8 millisievert between January and March 2012. The figure was relatively high compared with other quarters because the government conducted decontamination in areas with higher radiation levels on a trial basis during the period.
However, the health ministry said the number of workers surveyed is different from the total number of cleanup personnel reported by the Environment Ministry, which could mean the association failed to record radiation doses of all individuals working around the Fukushima plant.