Basic Study on actinide leaching and waste management of MCCI debris

2019 Fiscal Year Final Research Report

• Project/Area Number: 16H02447
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Nuclear engineering
• Research Institution: Kyoto University
• Principal Investigator: Sasaki Takayuki 京都大学, 工学研究科, 教授 (60314291)
• Co-Investigator(Kenkyū-buntansha): 桐島 陽 東北大学, 多元物質科学研究所, 教授 (00400424) ; 佐藤 修彰 東北大学, 工学研究科, 学術研究員 (70154078) ; 秋山 大輔 東北大学, 多元物質科学研究所, 助教 (80746751) ; 小林 大志 京都大学, 工学研究科, 准教授 (80630269)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: MCCI燃料デブリ / 核分裂生成物 / 溶出挙動 / ガラス固化 / 東京電力福島第一原子力発電所

Outline of Final Research Achievements

A simulated fuel debris of MCCI debris that occurred at the severe accident at FDNPS was prepared as a fundamental study for the proposal of the final disposal. The relationship between properties of the solid phase condition and leaching of U and fission products was investigated. Additionally, we proposed the vitrification method for stabilizing the generated debris. Unlike ordinary spent fuel mainly composed of uranium dioxide, the formation of calcium-uranium oxide was confirmed at high temperatures, and the uranium boride was formed by reaction with B in control rods. Various fission products were introduced by thermal neutron irradiation. Based on the concentration of nuclides eluted by immersion in artificial seawater etc., the knowledge of long-term chemical stability of MCCI debris when disposed was obtained. When the debris was vitrified under an anaerobic condition, the volume as waste increased, but a significant effect of suppressing elution of nuclides was found.

Free Research Field

バックエンド工学

Academic Significance and Societal Importance of the Research Achievements

本研究は、福島第一原発事故で発生したと考えられる様々な燃料デブリのうち、これまで殆ど知見の無いコンクリートと反応したデブリに着目し、デブリ固相の性状および水に対する化学的耐性を実験的に検討した。これらの基礎知見は、進行中の廃炉事業ならびにデブリ回収後の過度に保守的でない処理処分方策の立案に有益な情報をもたらすものである。