Environmental Restoration Efforts and Reconstruction Progress in FukushimaThe 28th UN Climate Change Conference (COP28)
Decontamination
Decontamination
In order to reduce the impact of radiation on people and the environment, radioactive materials are removed or covered with shielding materials.
Immediately after accident
Changes in the Air Dose Rate (Map of the area within 80 km)
* What is the air dose rate? The amount of radiation in the air is referred to as the air dose rate, and the air dose rate indicates the amount of air dose per hour.
Long-term Goals
In addition to the natural attenuation of radioactive materials, decontamination and health management measures are aimed to keep the additional exposure dose below 1 mSv/year in the long term.
Decontamination Methods
Radioactive cesium is easily adsorbed by clay minerals, and once fixed, it is difficult to dissolve in water. Therefore, in order to reduce the radiation dose from radioactive materials in the environment, we first took measures to remove, shield, and keep the soil with away from radioactive cesium attached.
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Residential Areas
Surface soil was removed from gardens, and replaced by additional soil from outside.
Leaves and other accumulated materials were removed from rain gutters.
Roofs were wiped, and accumulated materials were removed.
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Agricultural land
In rice paddies and fields, the following methods were taken:1) Surface soil was removed, and replaced by an additional soil 2) Reversal tillage which replaces bottom soil at a depth of around 30 cm 3) Deep plowing of fields
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Road
Remove sediments (leaves, moss, mud, etc.).
Paved surfaces may be cleaned with brushes or high-pressure water.
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Forest
Remove fallen leaves, branches, etc. within an effective area of approximately 20 m from the forest edge.
If removal of fallen leaves, etc. alone is not effective enough, remove remaining fine fallen leaves and other sedimentary organic residues.
Current Situation
Air dose rate also drops. A continuous decontamination effect has been observed.
Decontamination in residential areas reduced the radiation dose by 60%, and a subsequent investigation showed that it had fallen by 76%.This confirms that the effects of surface decontamination are being maintained.
[Timing]
Pre-decontamination measurement: Nov. 2011 – Nov. 2016
Post-decontamination measurement: Dec. 2011 – Nov. 2017
Subsequent monitoring: Oct. 2014 – Aug. 2018
* Average value of the air dose rate in residential areas, agricultural land, forests, and roads (aggregation of measurement point data)
* Residential areas include schools, parks, graveyards, and large-size facilities. Agricultural land includes fruit farms. Forests also include slopes, plains, and grasslands.
2022(139 months after the accident) Measurement Results by Aerial Monitoring
Air dose rate compared to the immediate aftermath of the accident is on a steady downtrend.
*These maps include air dose rates from natural radionuclides.
[Source]
Nuclear Power Steering Committee "Measurement Results by Aerial Monitoring in Fukushima Prefecture and Neighboring Prefectures" dated March 10, 2023
Status of evacuation zones as of May 2023
Surface decontamination has been completed except in restricted areas and evacuation orders in these areas have been lifted.
Air dose rates in Fukushima Prefecture have dropped to levels similar to those in major cities around the world.
