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Japanese

Assessment of Exposure Doses and Decontamination

（2019）

ＱIs the effectiveness of decontamination predictable?

ＡJAEA has developed a support system for decontamination activities that can accurately predict the effectiveness of decontamination and future air dose rates in short computing time. It is called RESET (Restoration Support System for Environment).
Two additional tools were developed later: ADRET, an air dose rate evaluation model that can simply estimate air dose rates, such as those after decontamination; and 3D-ADRES, which is, as opposed to ADRET, an advanced air dose rate evaluation model that can take into account even the effects of topographic features and terrestrial structures.

RESET was developed to support decontamination projects in areas contaminated by the accident at the Fukushima Daiichi Nuclear Power Station and has been used by Fukushima Prefecture, its municipalities where decontamination is underway, the Ministry of the Environment, etc. The system has also performed decontamination simulations and air dose rate predictions in response to requests from local governments in and outside of Fukushima Prefecture.


Example of analysis by RESET (Left: Dose rate distribution before decontamination; Right: Predicted dose rate distribution after decontamination)

Fig.1　Example of analysis by RESET (Left: Dose rate distribution before decontamination; Right: Predicted dose rate distribution after decontamination)

Example of RESET prediction of air dose rates after decontamination

Fig.2　Example of RESET prediction of air dose rates after decontamination

ADRET is a model to calculate air dose rates for flat land based on cesium distribution in soil.
The figure below is an example of estimations obtained by ADRET by request from an institution. It shows how much dose rates will decrease if surface soil is removed by decontamination.

Conceptual drawing of the ADRET calculation method（Malins et al., 2016）

Fig.3　Conceptual drawing of the ADRET calculation method (Malins et al., 2016)

Example of calculations by ADRET: Prediction of dose rate reductions achieved by surface soil removal

Fig.4　Example of calculations by ADRET: Prediction of dose rate reductions achieved by surface soil removal

3D-ADRES is a model to calculate air dose rates in complex environments with rough terrain, trees, and terrestrial structures. It is intended for detailed evaluations of dose rate distribution and the effectiveness of decontamination.

How 3D-ADRES performs calculations (based on a press release)

Fig.5　How 3D-ADRES performs calculations (based on a press release)

Related articles

Reference

  1. 長尾ほか(2019), 福島における放射性セシウムの環境動態研究の現状（平成30年度版）, JAEA-Research 2019-002, 235p.
  2. 山下・沢田(2020), 福島県の帰還困難区域の除染シミュレーションと将来予測, JAEA-Research 2019-010, 227p.
  3. Malins et al.(2016), Evaluation of ambient dose equivalent rates influenced by vertical and horizontal distribution of radioactive cesium in soil in Fukushima Prefecture, Journal of Environmental Radioactivity, Vol.151, Part 1, 38-49p.
  4. Kim et al.(2019), Simulation study of the effects of buildings, trees and paved surfaces on ambient dose equivalent rates outdoors at three suburban sites near Fukushima Dai-ichi, Journal of Environmental Radioactivity, Vol.210, 105803.
  5. 佐久間ほか(2018), 福島県内を想定した複雑な実環境中での空間線量率分布解析システム(3D-ADRES)の研究開発; リモートセンシング情報の活用と各環境因子(地形・土壌・建物・樹木等)の影響評価, RIST News, 64号, 3-16p.