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Reflections in Fukushima: The Fukushima Daiichi Accident Seven Years On via Greenpeace

Seven years after the start of the Fukushima Daiichi nuclear disaster and one year after the Japanese government lifted evacuation orders in areas of Namie and Iitate, radiation levels remain too high for the safe return of thousands of Japanese citizen evacuees. That is the conclusion of Greenpeace’s latest extensive radiation survey in Namie and Iitate, Fukushima prefecture. As a result of being invited by local citizens, Greenpeace was able to continue its survey work in Iitate, while also extending it to select homes in the highly contaminated exclusion (difcult to return) zone of Namie. Radiation risks, long term dose estimates and revision of targets In the areas of Iitate and Namie where evacuation orders were lifted in March 2017, contamination will remain well above international maximum safety recommendations for public radiation exposure of 1 milisievert per year (1mSv) for many decades. Greenpeace includes projections on dose rates to mid-21st century, which show that they will still be well in excess of the current government long term target levels of 0.23 micro-Sieverts per hour (µSv/h ). It is this target level that the government uses for its calculation to reach an estimated annual exposure level of 1mSv/y. The government calculation is based on citizens spending an average of 8 hours per day outside and taking account of shielding from radiation while inside a wooden house. Unless otherwise stated in the text, the Greenpeace calculation of annual human dose rates are based on radiation measurements taken at 1 meter, and what an adult’s exposure would be over one full year (total of 8,760 hours) at that specifc location.

In the case of radiation levels in the highly contaminated exclusion zone of Namie the situation is even more severe. It will be at least many decades more, and beyond the end of this century, before they start to even approach government targets. The Japanese government is well-aware of scientifc evidence of cancer and other health risks from low-dose radiation exposure, including in the range of 1-5 mSv/y. It has even part funded such research.1

Yet the government has opened areas of Namie and Iitate where citizens will be exposed to rates equal to this and higher, choosing instead to ignore the science to justify its Fukushima policies.

In a clear admission of the failure of its decontamination program, the Japanese government has recently begun a process to revise the current long term decontamination target of 0.23 µSv/h. In January 2018, during discussions on dose estimates for returning evacuees, the chair of the Nuclear Regulation Authority (NRA) stated that the current target “could hinder evacuees’ return home.”2 It has been insinuated that the new target would be in the 1.0 µSv/h range. The review of the target is to be conducted under the auspices of the Radiation Council of NRA.

Given the extent of contamination and the failure and limited nature of the decontamination program, radiation levels in Namie and Iitate are many decades and longer from reaching the current target.

Namie exclusion zone

The results of Greenpeace’s extensive survey around houses, farmland and forest in the Namie exclusion zone reveal radiation levels that far exceed the government’s long term decontamination target of 0.23 µSv/h. Average dose rates around homes between 25 km and 30 km northwest of the Fukushima Daiichi nuclear plant ranged from 1.3 – 3.4 µSv/h, with even higher levels in nearby forests and farmland. The home of Ms. Kanno in Namie, despite being subjected to an extensive decontamination program, had radiation levels with a weighted average of 1.3 μSv/h and with a maximum level of 5.8 µSv/h. In 60% of the nearby forested area current radiation levels would lead to an exposure dose of 17 mSv/y.

Radiation levels in the community of Obori in Namie, which is 20km west-north-west of the Fukushima Daiichi plant, were particularly concerning. This included measurements of 11.6 μSv/h, which would lead to an annual exposure of 101 mSv. […]

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