福島市内における個人線量測定と確率論的線量評価

Measurements of external doses to the population of Fukushima City

高原 省五  ; 木村 仁宣 ; 本間 俊充; 加藤 尊秋*; 西川 雅史*

Takahara, Shogo; Kimura, Masanori; Homma, Toshimitsu; Kato, Takaaki*; Nishikawa, Masashi*

本研究では、住民が日常生活を通じて受ける外部被ばく線量の分布を評価するために、確率論的な線量評価を実施した。福島市内において自宅の周辺線量当量と住民の屋外滞在時間を調査してそれぞれの分布形を定め、乱数を発生させて個人線量を評価するモデルの計算を実施し、個人の線量分布を評価した。評価結果は、測定値とおおむねよく一致していたが、線量の高い地域の屋外作業者についてはうまく再現することができなかった。正確に住民の線量を評価するためにはロケーションファクターの整備が必要である。

To assess distributions of individual doses from external exposures to the population groups living in the affected areas due to the Fukushima Dai-ichi Nuclear Power Station Accident, probabilistic dose assessments were performed based on the model developed by previous studies taking into account the experience of the Chernobyl accident. The distributions of individual doses were gained as the composite distribution of ambient dose equivalent rates and fractions of time spent at outdoors. The distributions of these parameters were determined based on the results of measurements in Fukushima City. The dose distributions obtained from probabilistic assessments were in good agreement with the measured ones for the population groups living in the area where ambient dose equivalents are low. In order to assess the doses accurately to the population living in the areas where doses are high, further investigations will be needed to evaluate location factors.