Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
斎須 要文*; 安藤 維彦*; 内山 恵三*; 上野 敏弘*; 瀧澤 孝一*; 遠藤 裕司*; 吉村 和也; 眞田 幸尚
Journal of Radiological Protection, 44(2), p.021518_1 - 021518_16, 2024/06
Following the accident at the Fukushima Daiichi Nuclear Power Station, evacuation orders were issued for the surrounding communities. In order to lift the evacuation order, it is necessary to determine individual external doses in the evacuated areas. The purpose of this study was to determine the quantitative relationship between individual external doses and ambient dose rates per hour as conversion coefficients. More specifically, individual external doses of Tokyo Electric Power Company Holdings employees in difficult-to-return zone were measured broadly over a long period (FY2020 to FY2022). To obtain highly accurate estimates, we used not only ambient dose rates based on airborne radiological monitoring data, but also Integrated dose rate map data that had been statistically corrected to correspond to local ambient dose rate gradients on the ground. As a result, the conversion coefficients based on the ambient dose rate map measured by airborne radiological monitoring were 0.42 for the Evacuation-Order Lifted Zones (ELZs), 0.37 for the Special Zones for Reconstruction and Rehabilitation (SZRRs), and 0.47 for the Difficult-to-Return Zones (DRZs) without a SZRRs. On the other hand, the conversion coefficients based on the Integrated dose rate map which is a highly accurate dose rate map based on statistical analysis of various types of monitoring that have been studied in government projects in recent years, were 0.78 for the ELZs, 0.72 for the SZRRs and 0.82 for the DRZs. Using these conversion coefficients, the individual external dose can be estimated from two representative ambient dose rate maps provided by the government.
斎須 要文*; 内山 恵三*; 石井 利明*; 安藤 維彦*; 上野 敏弘*; 中山 和美*; 佐藤 里奈; 吉村 和也; 眞田 幸尚
no journal, ,
2020年から2021年において、避難指示区域等における東京電力社員の屋外作業時の個人線量をのべ649日人分計測し、統計的な解析を行った。帰還困難区域に設けられた特定復興再生拠点区域では、2021年に計測した個人線量は2020年と比較して、中央値で30%の低減が確認でき、最大でも1時間当たりの被ばく線量は2.63Svであった。これらのデータについて、既存の空間線量率データと比較し考察を行った。