Chemisorption behavior of CsOH vapor on UO under high temperatures and various water vapor concentrations

Mohamad, A. B.; Nakajima, Kunihisa; Imoto, Jumpei*; Takano, Masahide

Journal of Nuclear Materials, 631, p.156826_1 - 156826_12, 2026/09

https://doi.org/10.1016/j.jnucmat.2026.156826

Data-driven on-site diagnostic technology: Predicting microbiologically influenced corrosion risk for ensuring long-term integrity (Contract research); FY2024 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Japan Agency for Marine-Earth Science and Technology*

JAEA-Review 2026-013, 86 Pages, 2026/07

JAEA-Review-2026-013.pdf:5.3MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), has been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") from FY2019. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), 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 FY2024, this report summarizes the research results of the "Data-driven on-site diagnostic technology: predicting microbiologically influenced corrosion risk for ensuring long-term integrity" conducted in FY2024. The present study aims to establish an innovative on-site diagnostic protocol capable of predicting microbiologically influenced corrosion (MIC) risks with high accuracy. To achieve this, we combined high-throughput analytical methods, simulated field experiments, and data-driven statistical analyses. Environmental samples were collected in Fukushima Prefecture to characterize microbial community structures and to develop key technologies for on-site genetic diagnostics. Using these samples, we evaluated the iron-corroding potential under various culture conditions and designed experimental systems simulating 1F environment. A high-throughput testing framework was validated for its ability to measure actual iron corrosion. In parallel, statistical approaches integrating microbial community profiles with MIC activity data were applied, yielding useful insights into both their applicability and limitations. Further, fixation methods for microbial observation in corrosion samples were examined, and optimal conditions were identified. Overall, the project provided valuable information on environmental microbial communities, cultivation of corrosion-associated microorganisms, and data-driven statistical approaches. These results lay the groundwork for the development of biomarker-based, ubiquitous diagnostic technologies for MIC applicable to diverse field environments, including those around 1F site.

Human resource development for research based on fuel debris study and SEEM-ology buildup (Contract research); FY2024 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*

JAEA-Review 2026-003, 173 Pages, 2026/06

JAEA-Review-2026-003.pdf:12.5MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), has been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") from FY2019. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F), 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 FY2024, this report summarizes the research results of the "Human resource development for research based on fuel debris study and SEEM-ology buildup" conducted in FY2024. The present study aims to buildup of "Severe Engineering Management (SEEM)-ology" that enables more rational decision-making in an uncertain and severe environment, and at the same time, to develop research personnel supporting the academic foundation of the extraction, long-term storage, treatment and disposal of fuel debris, which is a central issue in the decommissioning of 1F. Experts in different fields promote multiple research and human resource development tasks in organic collaboration. In the first fiscal year of this study, it was necessary to clarify specific research methods and set the direction in the [SEEM Fields] [Specialized Fields 12] and [Common Engineering Fields 13], as well as to prepare various conditions for necessary tests and analyses. It was also necessary to promote the operation of educational programs related to nuclear decommissioning and the planning of SEEM-related courses. For this reason, the purpose of this fiscal year was to obtain the prescribed results by examining specific research methods and making various preparations for conducting necessary tests, preparing various conditions, building and analyzing some measurement systems, and examining human resource development. Based on this objective, we set the performance targets and implementation methods for this fiscal year as an operational plan, implemented them as planned, and were able to achieve the targeted results in each technical field and education and human resource development activities.

Comparative effects of CO-curing condition on phase assemblage and mechanical response of CS pastes; Insights from atomic, crystallographic, and macroscopic deformations

Cho, S.*; Im, S.*; Tominaga, Aki; Shobu, Takahisa; Bae, S.*; 5 of others*

Journal of Building Engineering, 128, p.116694_1 - 116694_31, 2026/06

https://doi.org/10.1016/j.jobe.2026.116694

Cold sintering of whitlockite-based phosphate ceramics for ALPS carbonate slurry waste immobilization

Gubarevich, A.*; Kubo, Ryotaro*; Arisaka, Makoto; Osugi, Takeshi; Yoshida, Katsumi*; Takeshita, Kenji*

Journal of Nuclear Science and Technology, 63(6), p.667 - 676, 2026/06

https://doi.org/10.1080/00223131.2025.2592963

To immobilize and solidify carbonate-based Advanced Liquid Processing System (ALPS) sediment wastes, this study introduces a chemical transformation process that converts these wastes into calcium and magnesium phosphate phases, followed by densification using a novel cold sintering press (CSP) technique. Simulated calcium-magnesium carbonate slurries were treated with phosphoric acid to synthesize calcium and magnesium phosphates, which were then sintered at 300-500C using CSP. The effects of the calcium-to-magnesium ratio, strontium incorporation, and sodium chloride addition on phase composition and CSP densification were investigated. Dense bulk samples were successfully fabricated and characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and the Archimedes method. The results showed that the chemical transformation process led to the formation of whitlockite and newberyite, with the calcium-to-magnesium ratio determining the relative proportions of these phases. Strontium was effectively incorporated into the whitlockite crystal structure, while newberyite enhanced densification through a dehydration-driven process. Sodium chloride had no effect on chemical transformation and was not found in the final solid product. These results show that direct conversion of calcium-magnesium carbonate slurries to whitlockite-based phosphate ceramics, followed by CSP, enables stable solidification, making this method promising for ALPS sediment waste management.

Interplay of dynamic strain aging and dynamic precipitation in the Portevin-Le Chtelier effect in an Al-Mg-Zn-based crossover aluminum alloy

Zhang, X.*; Li, Y.*; Wei, S.*; Guo, H.*; He, Z.*; Yang, C.*; Gong, W.; Harjo, S.; Zhou, D.*; Li, Z.*; et al.

Acta Materialia, 308, p.121990_1 - 121990_18, 2026/04

https://doi.org/10.1016/j.actamat.2026.121990

Redox dynamics of cerium ions in soda-lime glass during cooling analyzed by in situ X-ray absorption fine structure

Ozawa, Saki*; Shiozawa, Yudai*; Saijo, Yoshitaka*; Miyajima, Tatsuya*; Matsumura, Daiju; Tsuji, Takuya; Nakase, Masahiko*; Maehara, Terutaka*

Journal of the American Ceramic Society, 109(3), p.e70621_1 - e70621_10, 2026/03

https://doi.org/10.1111/jace.70621

Oxygen chemical diffusion in fast neutron reactor fuel UPuAmO

Vauchy, R.; Horii, Yuta; Hirooka, Shun; Akashi, Masatoshi; Sunaoshi, Takeo*; Nakamichi, Shinya; Saito, Kosuke

Proceedings of 34th Nuclear Energy for New Europe (NENE2025) , p.232 - 238, 2026/01

Development of importance measures reflecting the risk triplet in dynamic probabilistic risk assessment; The Concept and measures of risk importance

Narukawa, Takafumi*; Takata, Takashi*; Zheng, X.; Tamaki, Hitoshi; Shibamoto, Yasuteru; Maruyama, Yu; Takada, Tsuyoshi

Journal of Nuclear Engineering (Internet), 6(4), p.49_1 - 49_14, 2025/12

https://doi.org/10.3390/jne6040049

Improvement of the RuO vapor-liquid transfer model in the chemical behavior analysis code SCHERN for accident of evaporation to dryness by boiling of reprocessed high level liquid waste

Yoshida, Kazuo; Hiyama, Mina*; Tamaki, Hitoshi

JAEA-Research 2025-011, 25 Pages, 2025/11

JAEA-Research-2025-011.pdf:2.15MB

An accident of evaporation to dryness by boiling of high-level radioactive liquid waste (HLLW) is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, volatile radioactive materials, such as ruthenium (RuO) are released from the tanks with water and nitric-acid mixed vapor into the atmosphere. Accurate quantitative estimation of released Ru is one of the important issues for risk assessment of those facilities. RuO is expected to be absorbed chemically into water dissolving nitrous acid (HNO). This behavior has been experimentally confirmed and plays an important role in the migration of Ru in the facility. A new model has been proposed as a chemical and physical absorption model based on the experimental results of the migration of RuO into nitric acid-water mixtures. In this study, to improve the analytical performance of SCHERN, these new analytical models have been incorporated and attempted to analyze the behavior of RuO in each phase. As a result, it has been observed a tendency that HNO in the liquid phase increases rapidly during the late boiling phase, when RuO release increases rapidly, and confirmed that this HNO concentration change significantly affects the subsequent migration behavior of RuO. These results indicate that it is essential to improve the analytical accuracy of the chemical behavior of HNO in each phase.