Study of generation mechanism of anthropogenetic radionuclides containing microparticles

Research Project

Project/Area Number	17K19086
Research Category	Grant-in-Aid for Challenging Research (Exploratory)
Allocation Type	Multi-year Fund
Research Field	Nuclear engineering, Earth resources engineering, Energy engineering, and related fields
Research Institution	Tokyo Institute of Technology
Principal Investigator	Ohnuki Toshihiko 東京工業大学, 科学技術創成研究院, 教授 (20354904)
Co-Investigator(Kenkyū-buntansha)	宇都宮聡九州大学, 理学研究院, 准教授 (40452792) 高野公秀国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門原子力科学研究所原子力基礎工学研究センター, リーダー (40501367) 香西直文国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門原子力科学研究所先端基礎研究センター, 研究主席 (80354877)
Project Period (FY)	2017-06-30 – 2020-03-31
Project Status	Completed (Fiscal Year 2019)
Budget Amount *help	¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000) Fiscal Year 2018: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000) Fiscal Year 2017: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000)
Keywords	福島原子力発電所事故 / マイクロ粒子 / 化学状態 / CsMP / 溶解 / 放射性セシウム / ヨウ素 / MCCI / エアロゾル発生機構
Outline of Final Research Achievements	Highly radioactive cesium-rich microparticles (CsMPs) were released from the Fukushima Daiichi Nuclear Power Plant to the surrounding environments at the early stage of the nuclear disaster. These CsMPs should involve not only Cs, but also I. However, the characteristics of Cs and I in the CsMPs are still unknown. We analyzed characteristics of Cs and I in the simulated CsMPs. The simulated CsMPs are analyzed elemental compositions by SEM and chemical forms by XANES. SEM analyses showed that many round particles of different diameters between ~2 micro-m and several tens micro-m are present in the simulated CsMP samples. EDX analyses indicate that simulated CsMP icontained Cs and I. XANES analyses indicated that the simulated CsMPs contain Cs possessing different chemical species from CsI, which is insoluble with deionized water. Almost all I are present as the chemical species of CsI in the simulated CsMP, and are dissolved with deionized water.
Academic Significance and Societal Importance of the Research Achievements	福島第一原子力発電所事故により生成した放射性Csを含むマイクロ粒子の生成機構を解明するため、Cs及びIを含むマイクロ粒子を実験により合成したことは初めての試みである。さらに、マイクロ粒子中のCs及びIの化学状態を明らかにした点は、放射性Cs及び放射性Iの環境中の挙動及び人体への被爆の評価に対しても重要である。