Elucidation of actinide colloidal reaction under contaminated water conditions at Fukushima Daiichi Nuclear Power Station

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K14160
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 31010:Nuclear engineering-related
• Research Institution: Japan Atomic Energy Agency
• Principal Investigator: Ouchi Kazuki 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, 研究職 (10760407)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: アクチノイド化学 / ウラン / ネプツニウム / 電解析出 / コロイド / 電気化学 / X線吸収微細構造

Outline of Final Research Achievements

Since the contaminated water generated at the Fukushima Daiichi Nuclear Power Station accident is a heterogeneous system and a condition in which actinide (An) colloid is likely to form, it is difficult to understand the behavior of An. In this study, we investigated the An colloid reaction in close to contaminated water conditions including (1)valence change, (2) colloid/micronization, and (3) interaction with inorganic ions. It was clarified that the formation process of An deposits following the valence change formed hydroxide as an intermediate and changed to oxide. We also found that the deposition was suppressed by sulfate ion.

Free Research Field

アクチノイド化学

Academic Significance and Societal Importance of the Research Achievements

本研究では，ウラン（U）とネプツニウム（Np）の原子価変化に伴う析出反応過程を解明するとともに，硫酸イオンによる析出抑制の効果を見出した．得られたAn析出物の形成機構や反応性に関する知見は，福島第一原子力発電所事故で発生した汚染水中のα核種含有微粒子の由来や反応予測に貢献できると期待される．また，UとNpの析出反応は，形成した析出物の電気抵抗値により析出の進行に大きな違いを及ぼすという新規の知見が得られ，学術的意義も大きい．