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Study on the surface deposition of radionuclides derived from the Fukushima Daiichi nuclear accident

Research Project

Project/Area Number 18K11633
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 63010:Environmental dynamic analysis-related
Research InstitutionNational Institute of Advanced Industrial Science and Technology

Principal Investigator

Kaneyasu Naoki  国立研究開発法人産業技術総合研究所, エネルギー・環境領域, 上級主任研究員 (00356809)

Co-Investigator(Kenkyū-buntansha) 忽那 周三  国立研究開発法人産業技術総合研究所, エネルギー・環境領域, 上級主任研究員 (60344131)
Project Period (FY) 2018-04-01 – 2022-03-31
Project Status Completed (Fiscal Year 2021)
Budget Amount *help
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2020: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000)
Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2018: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Keywords放射性核種沈着 / 雲水沈着 / ヨウ素 / 乾性沈着速度 / 地表面沈着 / 雲底高度 / 表面抵抗 / 霧雨 / 放射性核種 / 放射性ヨウ素
Outline of Final Research Achievements

To explore the possible cloudwater deposition that formed a distinctive contamination profile during the Fukushima Dai-ich nuclear accident, data from pollen sensors deployed nationwide were analyzed. Considering the existing knowledge on vertical gradients of cloudwater composition, a formation process was proposed for the observed vertical distribution, that is, surface contamination occurred intensively at the contact line between the cloud base and mountain slopes via cloudwater deposition, and the descending cloud base formed the contamination zone.
In addition, uptake of molecular iodine (I2) by clay minerals and aqueous solutions was investigated in the laboratory experiments to estimate the surface resistance, which is essential in calculating the dry deposition velocity. Our results show that using surface resistance of sulfur dioxide for soils as a proxy of I2 in atmospheric transport/deposition models may result in substantial errors under low relative humidity conditions.

Academic Significance and Societal Importance of the Research Achievements

これまで、大気輸送拡散モデルを用いた放射能汚染域の再現あるいは放射性物質大気中濃度の評価は、沈着モジュールの種類やパラメータの変更、対象物質の物理化学特性あるいは気象データの差し替えなどにより精度の改善を図ろうとしてきた。しかし、本研究はこれまで気付かれていなかったデータを発掘し、解析することにより放射性核種の地表面沈着過程に関して新たな視点を提示し、モデル内のモジュールをいじる以上の対処の必要性を示した。また、代理物質の特性を用いずにヨウ素そのものの乾性沈着速度を計算するための基礎となるデータを提供した。これは放射性ヨウ素による被曝量の推定精度向上に向けて学術面のみならず社会的意義を有する。

Report

(5 results)
  • 2021 Annual Research Report   Final Research Report ( PDF )
  • 2020 Research-status Report
  • 2019 Research-status Report
  • 2018 Research-status Report
  • Research Products

    (7 results)

All 2021 2020 2019 2018

All Presentation (7 results) (of which Int'l Joint Research: 1 results)

  • [Presentation] 分子状ヨウ素の乾性沈着速度のラボ実験2021

    • Author(s)
      兼保直樹、忽那周三
    • Organizer
      第62回大気環境学会年会
    • Related Report
      2021 Annual Research Report
  • [Presentation] 土壌成分によるヨウ素分子蒸気の取り込み速度とその湿度依存性(矩形パルス法実験)2020

    • Author(s)
      忽那周三、兼保直樹
    • Organizer
      日本化学会第100春季年会
    • Related Report
      2019 Research-status Report
  • [Presentation] Detection of cloud droplets or fog by a polarization optical counting sensor: Circumstantial evidence for cloudwater deposition of radionuclides in mountainous areas of Japan during the Fukushima nuclear accident2019

    • Author(s)
      Naoki Kaneyasu
    • Organizer
      The 8th International Conference on Fog, Fog Collection and Dew, Taipei, Taiwan
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research
  • [Presentation] ヨウ素分子I2の乾性沈着地表面抵抗の評価(室内実験)2019

    • Author(s)
      忽那周三、兼保直樹
    • Organizer
      第60回大気環境学会年会
    • Related Report
      2019 Research-status Report
  • [Presentation] ヘサキナールのヘンリー定数と水和反応平衡定数の決定2019

    • Author(s)
      忽那周三、兼保直樹
    • Organizer
      第60回大気環境学会年会
    • Related Report
      2019 Research-status Report
  • [Presentation] 慣性沈着表面抵抗スケーリング係数の評価―矩形パルス法の利用2018

    • Author(s)
      忽那周三、兼保直樹
    • Organizer
      第59回大域環境学会年会
    • Related Report
      2018 Research-status Report
  • [Presentation] 花粉センサー・データを利用した接地雲(霧)の検出 -福島事故起源の放射性核種沈着メカニズムとして-2018

    • Author(s)
      兼保直樹、忽那周三、古田泰子
    • Organizer
      2018日本気象学会2018年度秋季大会
    • Related Report
      2018 Research-status Report

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Published: 2018-04-23   Modified: 2023-01-30  

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