Fundamental study on applicability of fluorous solvents and ionic liquids as extraction media for thorium fuel reprocessing

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K19047
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 31:Nuclear engineering, earth resources engineering, energy engineering, and related fields
• Research Institution: Tokai University
• Principal Investigator: Asanuma Noriko 東海大学, 工学部, 准教授 (70439660)
• Co-Investigator(Kenkyū-buntansha): 稲津 敏行 東海大学, 工学部, 教授 (70151579)
• Project Period (FY): 2018-06-29 – 2022-03-31
• Keywords: 溶媒抽出 / フルオラス溶媒 / イオン液体 / セリウム / 核分裂生成物

Outline of Final Research Achievements

Applicability of fluorous solvents and ionic liquids were investigated as media of solvent extraction for thorium fuel reprocessing. It is known that fluorous solvent have high chemical stability, and ionic liquids have high solubility of extraction chemical species. Cerium was used as a simulated element of thorium. Cerium in nitric acid was extracted to the fluorous solvent phase containing a phosphate type fluorous extractant. After that, cerium was distributed to an imidazolium-type ionic liquid phase containing trioctylmethylammonium chloride as an extractant. In the examination of extraction from the simulated thorium fuel dissolved solution by using simulated elements of fission products, it is found that cerium was selectively recovered to the ionic liquid phase through the fluorous solvent phase.

Free Research Field

原子力工学

Academic Significance and Societal Importance of the Research Achievements

新しい学問領域であるフルオラス科学を原子力工学分野の化学分離へ適用させる取り組みであり、異分野の融合を図ることにつながった。フルオラス溶媒もイオン液体も抽出媒体としての基礎的知見は蓄積されており、互いの長所短所を把握したうえで課題解決に臨むことができた。トリウム燃料再処理には技術的課題が多く、既存の概念だけでは解決困難だが、フルオラス溶媒とイオン液体を組み合わせた抽出プロセスは、提案者らの独自手法であり、本研究で原理的な成立性を確認できた。今後、工学的な見地による検討を進めることで、トリウム燃料サイクルの確立に貢献できるだけでなく、他の分野への適用も期待できる。