Advanced speciation method for Iodine-129 in the terrestrial environment

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K22337
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0202:Condensed matter physics, plasma science, nuclear engineering, earth resources engineering, energy engineering, and related fields
• Research Institution: Japan Atomic Energy Agency
• Principal Investigator: Honda Maki 国立研究開発法人日本原子力研究開発機構, 安全研究・防災支援部門 安全研究センター, 博士研究員 (80881432)
• Project Period (FY): 2020-09-11 – 2023-03-31
• Keywords: 環境放射能 / I-129 / スペシエーション

Outline of Final Research Achievements

To identify the primary physicochemical forms controlling the migration behavior of I-129 in groundwater, an original scheme combining UV irradiation (decomposition of organic matter) and sequential filtration (separation into dissolved and suspended I-129) was developed, and this analytical method was applied to groundwater samples. As a result, total I-129 (suspended + dissolved), suspended I-129 (>0.45 μm), and dissolved I-129 (suspended matter below 0.45 μm and above 10 kDa, and ions) were successfully assessed. In groundwater at a depth of 250 m below the surface, the amount of dissolved I-129 (number of atoms) was lower than the amount of suspended I-129, indicating that I-129 was flowing deep underground with suspended matter of larger particle size.

Free Research Field

環境放射能

Academic Significance and Societal Importance of the Research Achievements

本研究では従来は困難であった環境試料で、I-129スペシエーションの分析に成功した。地下水試料だけでなく、本分析手法を河川水等の水試料に適用することで、水圏におけるI-129の移行挙動を支配する主要な物理化学的形態を特定できる可能性がある。従って本研究成果は、原子力施設から継続的に環境に放出されているI-129の複雑な生物地球化学的循環システムにおける移行挙動の解明に資するものである。