Validation study of ambient dose equivalent conversion coefficients for radiocaesium distributed in the ground; Lessons from the Fukushima Daiichi Nuclear Power Station accident

地中で指数関数的に分布した放射性セシウムのインベントリーから空間線量当量率への換算係数のヴァリデーション; 福島第一原子力発電所事故からの教訓

越智 康太郎   ; 舟木 泰智 ; 吉村 和也  ; 飯本 武志*; 松田 規宏  ; 眞田 幸尚   

Ochi, Kotaro; Funaki, Hironori; Yoshimura, Kazuya; Iimoto, Takeshi*; Matsuda, Norihiro; Sanada, Yukihisa

The ambient dose equivalent conversion coefficient (ADC) for converting from the radionuclide inventory to the ambient dose equivalent rate (ambient dose rate) is used to estimate exposure doses. We have collected actual data, ambient dose rate at 1 m above the ground level and vertical distribution of radiocesium in the soil sample, around the Fukushima Daiichi Nuclear Power Station (FDNPS). The actual data during FY2011-FY2019 is used for confirming the validity of ADC. The ADC assuming the vertical distribution of radioceisum were calculated with relaxation mass depth. Good correlation was found between the calculated inventory by the ambient dose rate and ADC in this study and actual radiocesium inventory. Therefore, the ADC in this study sufficiently reflected the actual deposition status of radiocesium on the ground surface after the FDNPP accident.