Optimising sodium incorporation into potassium-activated metakaolin-based alkali-activated materials

Chaerun, R. I.; Sato, Junya; Hiraki, Yoshihisa; Yoshida, Yukihiko; Sato, Tsutomu*; Osugi, Takeshi

Construction and Building Materials, 500, p.144270_1 - 144270_10, 2025/11

https://doi.org/10.1016/j.conbuildmat.2025.144270

Alkali-activated materials (AAMs), particularly those derived from metakaolin, have gained significant attention as sustainable binders for hazardous waste immobilisation, owing to their dense microstructure and chemical durability. Their amorphous aluminosilicate framework enables effective encapsulation of hazardous materials and reduces environmental risks. However, maintaining the stability of this amorphous network is challenging, particularly when sodium (Na)-rich precursors are used, as excess Na) promotes crystallisation and compromises matrix integrity. This study systematically investigates the influence of Na) concentration on the structural stability of metakaolin-based AAMs activated primarily with potassium (K)). The objective is to identify the threshold Na incorporation level that preserves the amorphous structure and maintains chemical stability. Transmission electron microscopy (TEM), Raman spectroscopy, and thermodynamic modelling were employed to examine the structural evolution of K-AAMs across a range of Na:K molar ratios. The results reveal that higher Na:K ratios induce nanopore formation and early crystallisation of Na-rich zeolitic phases, which can reduce matrix stability. In contrast, an optimal Na:K ratio was identified that maintains the amorphous network and preserves the aluminosilicate framework. These findings provide valuable insights into optimising K-AAMs for advanced, durable waste encapsulation technologies.

Achievements and status of the STRAD project for radioactive liquid waste management

Arai, Yoichi; Watanabe, So; Nakahara, Masaumi; Funakoshi, Tomomasa; Hoshino, Takanori; Takahatake, Yoko; Sakamoto, Atsushi; Aihara, Haruka; Hasegawa, Kenta; Yoshida, Toshiki; et al.

Progress in Nuclear Science and Technology (Internet), 7, p.168 - 174, 2025/03

https://doi.org/10.15669/pnst.7.168

The Japan Atomic Energy Agency (JAEA) has been conducting a project named "Systematic Treatment of RAdioactive liquid waste for Decommissioning (STRAD)" project since 2018 for fundamental and practical studies for treating radioactive liquid wastes with complicated compositions. Fundamental studies have been conducted using genuine liquid wastes accumulated in a hot laboratory of the JAEA called the Chemical Processing Facility (CPF), and treatment procedures for all liquid wastes in CPF were successfully designed on the results obtained. As the next phase of the project, new fundamental and practical studies on primarily organic liquid wastes accumulated in different facilities of JAEA are in progress. This paper reviews the representative achievements of the STRAD project and introduces an overview of ongoing studies.

High-rate performance of a time projection chamber for an H-dibaryon search experiment at J-PARC

Kim, S. H.*; Ichikawa, Yudai; Sako, Hiroyuki; Hasegawa, Shoichi; Hayakawa, Shuhei*; Nanamura, Takuya*; Sato, Susumu; Tanida, Kiyoshi; Yoshida, Junya; 11 of others*

Nuclear Instruments and Methods in Physics Research A, 940, p.359 - 370, 2019/10

https://doi.org/10.1016/j.nima.2019.06.050

Observation of a Be double-Lambda hypernucleus in the J-PARC E07 experiment

Ekawa, Hiroyuki; Ashikaga, Sakiko; Hasegawa, Shoichi; Hashimoto, Tadashi; Hayakawa, Shuhei; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Kimbara, Shinji*; Nanamura, Takuya; et al.

Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.021D02_1 - 021D02_11, 2019/02

https://doi.org/10.1093/ptep/pty149

Case studies of radiation dose assessment in emergency situation of nuclear facilities

Kawasaki, Masatsugu; Nakajima, Junya; Yoshida, Keisuke; Kato, Saori; Nishino, Sho; Nozaki, Teo; Nakagawa, Masahiro; Tsunoda, Junichi; Sugaya, Yuki; Hasegawa, Rie; et al.

JAEA-Data/Code 2017-004, 57 Pages, 2017/03

JAEA-Data-Code-2017-004.pdf:2.34MB

In emergency situation of nuclear facilities, we need to estimate the radiation dose due to radiation and radioactivity to grasp the influence range of the accident in the early stage. Therefore, we prepare the case studies of dose assessment for public exposure dose and personal exposure dose and contribute them to emergency procedures. This document covers about accidents of nuclear facilities in Nuclear Science Research Institute and past accident of nuclear power plant, and it can be used for inheritance of techniques of emergency dose assessment.

Topological transition from accretion to ejection in a disk-jet system; Singular perturbation of the Hall effect in a weakly ionized plasma

Shiraishi, Junya; Yoshida, Zensho*; Furukawa, Masaru*

Astrophysical Journal, 697(1), p.100 - 105, 2009/03

https://doi.org/10.1088/0004-637X/697/1/100

A thin disk accompanied by spindle-like jet, created commonly near massive central objects, exhibits a topologically singular aspect when viewed from an ideal macroscopic theory. The accreting inflow and jet's outflow are "singular perturbation" on the ambient Keplerian rotation, which are generated by some non-ideal higher-order (in the order of derivatives) effect. The Hall effect can generate such a structure in a weakly ionized plasma of a protostellar disk. Numerical estimate of the characteristic length scale defined by the singular perturbation justifies the precedence of the Hall effect.

J-PARC E07, systematic study of double strangeness nuclei with hybrid emulsion method

Yoshida, Junya

no journal, , 

The studies of double strangeness nuclei play an important role for modern hadron physics because they have been providing information about Lambda-Lambda and Xi-Nucleon interaction as extensions of nuclear force. J-PARC E07 is a unique experiment at J-PARC to investigate double strangeness nuclei with hybrid emulsion method. This experiment was designed to obtain ten times more double strangeness nuclei than that obtained by previous experiments. Moreover, it aims the first measurement of X-ray from Xi-atom by Germanium detector. The beam exposure of E07 was successfully completed in 2016 and 2017. New double strangeness nuclear events will be detected in the near future through the analysis of emulsion sheet. I will report the present status and the future prospect of the experiment.

Status of J-PARC E07

Yoshida, Junya; Hayakawa, Shuhei; Ekawa, Hiroyuki*; Yoshimoto, Masahiro*; Kasagi, Ayumi*; Lin, P. M.*; Nyaw, A. N. L.*; Nakazawa, Kazuma*

no journal, , 

J-PARC E07 is an experiment with the photographic emulsion technique to detect 10 times higher statistics of double hypernuclei compared to the past experiments. This experiment aims to obtain quantitative data on - and -nucleon interaction, by the mass measurement of various double hypernuclei. As of July 2019, we have scanned about 53% of 1300 emulsion sheets at least once and detected about 30 candidate events of double hypernuclei. We start a study of the branching ratio of the decay mode with the accumulating data. However, the detection efficiency is about half of the designed value. It is due to the rugged surface position of emulsion module. We are developing the correction method to reconstruct its original geometry by using proton tracks which punch through SSD and emulsion sheets.

Current and future perspectives of collaborative activities of academic society on radiation protection, 3; Efforts to train and secure on radiation protection experts in nuclear emergencies

Takada, Chie; Nakano, Masanao; Munakata, Masahiro; Yoshida, Tadayoshi; Yokosuka, Yoshiyuki; Yamada, Junya; Maeda, Eita; Watanabe, Yuki; Tomioka, Akifumi; Momose, Takumaro

no journal, , 

no abstracts in English

Analysis status of scattering events in the J-PARC E40 experiment

Nanamura, Takuya; Ichikawa, Yudai; Hayakawa, Shuhei; Yoshida, Junya; Miwa, Koji*; Honda, Ryotaro*; Akazawa, Yuya*; Yamamoto, Takeshi

no journal, , 

Hyperon-nucleon scattering experiment is one of the powerful methods for studying YN interaction. However, it is difficult due to short lifetime of hyperon. scattering experiments were performed as KEK E251 and KEK E289 in order to measure the differential cross sections. In these experiments, statistics were limited to less than 100 events and differential cross section had too large statistical errors to restrict baryon-baryon interaction models. J-PARC E40 experiment aims for measuring cross sections of scatterings with high statistics (10000 events) by overcoming difficulties of hyperon-nucleon scattering experiment. By using high rate ( 19M /spill) beam and large acceptance spectrometer, we can produce and tag large amount of beam. LH target and surrounding detector system CATCH enable us to reconstruct reactions from two body kinematics. Our experimental group completed data taking and about half of data taking by 2019 Apr. Left data taking will be performed in the end of this fiscal year.