Assessment of radiation doses from ingestion pathway to the public in Fukushima prefecture after the Fukushima Dai-ichi Nuclear Power Plant accident

福島第一原子力発電所事故後の福島県内における住民の食物摂取経路からの被ばく線量評価

高原 省五  ; 渡邊 正敏*

Takahara, Shogo; Watanabe, Masatoshi*

経口摂取による公衆の内部被ばくは、福島事故後の被ばく線量評価において最も関心の高い被ばく経路の一つである。本研究では、福島事故後の最新知見をもとに、食品中核種濃度の減衰速度や調理過程における濃度低減を考慮して被ばく線量の予測モデルを開発した。開発したモデルを用いて遡及的な評価を行ったところ、同経路からの被ばく線量は事故後1年目に数10Sv程度であり、その後は年間数Svを超えることなく単調に減衰していくことが分かった。また、これらの結果は、マーケットバスケット法,陰膳法及び汚泥中濃度に基づく逆推定法による先行研究と整合性のある結果となった。

Internal exposure from ingestion pathway is one of most concerned contributor to the received doses to the public after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In the present study, we developed the dose prediction model taking into account the ecological half-lives of radionuclides in foodstuffs and the reduction effects on concentration of radionuclides in cooking-process based on the experiences and the latest insights of the FDNPP accident. From comparison of the retrospective assessment results in Fukushima city between our models and the previous models (market bascket, duplicate, sewer sludge method), no contradictions were observed. In addition, it was found that the potential annual effective doses, which were assessed using the developed model, is several tens micro Sieverts in the first year after the FDNPP accident, and subsequent years the doses is also not exceeding several micro Sv for the future in Fukushima city.