Design and characterisation of different characteristics of metakaolin-based geopolymer for fuel debris removal (Contract research); FY2023 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Hokkaido University*

JAEA-Review 2025-041, 79 Pages, 2025/12

JAEA-Review-2025-041.pdf:9.8MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2023. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2023, this report summarizes the research results of the "Design and characterisation of different characteristics of metakaolin-based geopolymer for fuel debris removal" conducted in FY2023. This study aims to demonstrate the potential of metakaolin-based geopolymer, which has high fluidity and confinement performance, and incorporates neutron absorption capability through boron addition, for the stabilization and solidification of radioactive waste from fuel debris and contaminated water treatment. In this year, the research focused on the design and evaluation of metakaolin geopolymer with and without boron, the interaction between metakaolin-based geopolymer and FeO colloids, the characterization of geopolymer, and the property evaluation of simulated waste solidification samples. The influence of metakaolin's particle size and firing temperature on its leaching rate, and fluidity, hardening properties of geopolymer was investigated in detail. Additionally, the effects of boron addition in alkaline solution properties and extended hardening time were confirmed. In the interaction with colloids, the confinement of colloids and dimensional changes within the geopolymer were evaluated. Furthermore, solidification samples with simulated waste were prepared, and viscosity changes during the curing process were measured. Hardening time and temperature changes during curing were measured. Compression strength measurements and -ray irradiation tests were also conducted, and through the measurement of hydrogen generation, important basic data on the properties of the solidified bodies were obtained. In research promotion, collaboration with Hokkaido University, JAEA, Sobueclay Co. Ltd., and the University of Sheffield was strengthened through regular meetings and data sharing, and plans for the following years were finalized. Additionally, a human resource development program was launched.

Possible pathway of zeolite formation through alkali activation chemistry of metakaolin for geopolymer-zeolite composite materials; ATR-FTIR study

Onutai, S.; Sato, Junya; Osugi, Takeshi

Journal of Solid State Chemistry, 319, p.123808_1 - 123808_10, 2023/03

https://doi.org/10.1016/j.jssc.2022.123808

Synthesis of a Si-Al gel as a starting material of aluminosilicate solids

Sato, Junya; Shiota, Kenji*; Takaoka, Masaki*

Zairyo, 70(5), p.406 - 411, 2021/05

https://doi.org/10.2472/jsms.70.406

An aluminosilicate solid is an inorganic material that has the property of immobilizing heavy metals or radionuclides in the matrix. In this study, aluminosilicates with a Si/Al molar ratio of 0.5 was synthesized from a chemical reagent in order to produce aluminosilicate solids with a low Si/Al molar ratio, which were expected to improve the immobilization of heavy metals and radionuclides contained in the matrix. The synthesized Si-Al gel with a Si/Al molar ratio of 0.5 had little impurity content and was in an amorphous phase. In addition, the compressive strength of the aluminosilicate solid produced by the synthesized Si-Al gel showed a 5 MPa or more, confirming that it can be used as a raw material for aluminosilicate solids. The aluminosilicate solid with a Si/Al molar ratio of 1.25 had a dense surface structure from the result of BSE images and had the highest compressive strength among all samples.