Methods for regulating depth of corrosion fissures in simulated fastener holes of 7050-T7451 aluminum alloy

青山 高士; Choudhary, S.*; Pandaleon, A.*; Burns, J. T.*; Kokaly, M.*; Restis, J.*; Ross, J.*; Kelly, R. G.*

Corrosion, 81(6), p.609 - 621, 2025/06

https://doi.org/10.5006/4739

This study presents a new test method for inducing controlled corrosion damage within simulated fastener holes of aluminum alloys, aimed at pretreating fatigue test specimens. The method involves insulating the outer surface while exposing the fastener hole surface to electrolytes containing 0.66 M NaCl + 0.1 M AlCl with varying concentrations of K S O . The evolution of corrosion damage within the fastener hole was examined as a function of exposure duration, electrolyte composition, and volume, as well as the effect of galvanic coupling with a SS316 cathode. Results indicate that fissure depth increases with an increase in K S O concentration but does not progress further after 24-48 hours of exposure in the chemical, or freely-corroding, exposure test. In contrast, galvanic coupling with a SS316 plate significantly accelerates corrosion, leading to much deeper fissures in a shorter time. The importance of electrolyte replenishment has been explored using electrochemical measurements, revealing the impact of evolving electrolyte chemistry. Beyond its application in fatigue specimen pretreatment, this method provides a simple yet effective approach for studying localized corrosion and evaluating mitigation strategies for fastener holes in aerospace structures.

Magnetism of kagome metals (FeCo)Sn studied by SR

Cai, Y.*; Yoon, S.*; Sheng, Q.*; Zhao, G.*; Seewald, E. F.*; Ghosh, S.*; Ingham, J.*; Pasupathy, A. N.*; Queiroz, R.*; Lei, H.*; et al.

Physical Review B, 111(21), p.214412_1 - 214412_17, 2025/06

https://doi.org/10.1103/PhysRevB.111.214412

We study the magnetic properties of the metallic kagome system (FeCo)Sn by a combination of muon spin relaxation (SR), magnetic susceptibility, and scanning tunneling microscopy (STM) measurements in single crystal specimens with Co concentrations = 0, 0.11, 0.8. In the undoped antiferromagnetic compound FeSn, we find possible signatures for a previously unidentified phase that sets in at ~K, well beneath the Neel temperature ~K as indicated by a peak in the relaxation rate 1/ observed in zero field (ZF) and longitudinal field (LF) SR measurements, with a corresponding anomaly in the ac and dc susceptibility, and an increase in the static width 1/ in ZF-SR measurements. No signatures of spatial symmetry breaking are found in STM down to 7~K. Related to the location and motion of muons in FeSn, we confirmed a previous report that about 40% of the implanted muons reside at a field-cancelling high symmetry site at ~K, while an onset of thermal hopping changes the site occupancy at higher temperatures. In FeCoSn, where disorder eliminated the field-cancellation effect, all the implanted muons exhibit precession and/or relaxation in the ordered state. In FeCoSn, we find canonical spin glass behavior with freezing temperature ~K; the ZF and LF-SR time spectra exhibit results similar to those observed in dilute alloy spin glasses CuMn and AuFe, with a critical behavior of at and as . The absence of spin dynamics at low temperatures makes a clear contrast to the spin dynamics observed by SR in many geometrically frustrated spin systems on insulating kagome, pyrochlore, and triangular lattices. The spin glass behavior of CoSn doped with dilute Fe moments is shown to originate primarily from the randomness of doped Fe moments rather than due to geometrical frustration of the underlying lattice.

Incommensurate antiferromagnetism in UTe under pressure

Knafo, W.*; Thebault, T.*; Raymond, S.*; Manuel, P.*; Khalyavin, D. D.*; Orlandi, F.*; Ressouche, E.*; Beauvois, K.*; Lapertot, G.*; 金子 耕士; et al.

Physical Review X, 15(2), p.021075_1 - 021075_16, 2025/05

https://doi.org/10.1103/PhysRevX.15.021075

The discovery of multiple superconducting phases in UTe boosted research on correlated-electron physics. This heavy-fermion paramagnet was rapidly identified as a reference compound to study the interplay between magnetism and unconventional superconductivity with multiple degrees of freedom. The proximity to a ferromagnetic quantum phase transition was initially proposed as a driving force to triplet-pairing superconductivity. However, we find here that long-range incommensurate antiferromagnetic order is established under pressure. The propagation vector k = (0.07, 0.33, 1) of the antiferromagnetic phase is close to a wavevector where antiferromagnetic fluctuations have previously been observed at ambient pressure. These elements support that UTe is a nearly-antiferromagnet at ambient pressure. Our work appeals for theories modelling the evolution of the magnetic interactions and electronic properties, driving a correlated paramagnetic regime at ambient pressure to a long-range antiferromagnetic order under pressure. A deeper understanding of itinerant-f-electrons magnetism in UTe will be a key for describing its unconventional superconducting phases.

Incorporation of boron into metakaolin-based geopolymers for radionuclide immobilisation and neutron capture potential

Niu, X.*; Elakneswaran, Y.*; Li, A.*; Seralathan, S.*; 菊池 亮佑*; 平木 義久; 佐藤 淳也; 大杉 武史; Walkley, B.*

Cement and Concrete Research, 190, p.107814_1 - 107814_17, 2025/04

https://doi.org/10.1016/j.cemconres.2025.107814

Metakaolin-based geopolymers have attracted significant interest in decontaminating radioactive debris from the Fukushima nuclear accident. This study explored the incorporation of boron (B) into geopolymers using boric acid as the source, with the goal of developing B-enriched geopolymers for enhanced radionuclide immobilisation and neutron capture potential.

2023年度人形峠環境技術センターにおける研究・技術開発成果; トピックス

人形峠環境技術センター

JAEA-Review 2024-050, 55 Pages, 2025/03

JAEA-Review-2024-050.pdf:3.57MB

本報告書は、2023年度に人形峠環境技術センターが実施した研究開発や技術開発に係る主要な業務を概説するものである。人形峠環境技術センターでは、2001年まで核燃料サイクルにおける上流側(フロントエンド)と言われるウランの探鉱から採鉱、製錬、転換、そしてウラン濃縮までの技術開発を実施し、現在ではこれら開発に使用してきた施設・設備の解体・撤去に取り組んでいる。また、2016年に公表した「ウランと環境研究プラットフォーム」構想に基づき、ウラン廃棄物を安全に処理・処分するための研究開発にも取り組んでいる。ウランと環境をテーマとした研究開発は、人形峠周辺環境の特徴を活かした「環境研究」及び人形峠環境技術センターの施設やポテンシャルを活かした「ウラン廃棄物工学研究」に大別される。また、安全や現場管理に関する技術開発、保健物理や放射線生物学の視点から放射線影響評価に関する研究も進めている。本報告書では、環境研究や環境保全として、花崗岩山間地における地下水流動の特徴に関する調査、鉱物への微量元素の分配に関する基礎と応用について報告する。ウラン廃棄物工学研究として、レーザーを利用した除染技術開発、廃棄体容器材料に関する調査について報告する。保障措置として、人形峠環境技術センターのウラン濃縮施設における、課題や取り組みについて報告する。安全技術・設備開発として、鉱さいたい積場の防災対策について、また放射線影響評価研究として、ラドンのリスクと生体影響の評価について報告する。これら研究・技術開発の成果は、論文等を通じて積極的に外部発表するよう努めている。

Measurements of neutron capture cross-section for nuclides of interest in decommissioning (II); Fe(n,)Fe

中村 詔司; 芝原 雄司*; 遠藤 駿典; Rovira Leveroni, G.; 木村 敦

Journal of Nuclear Science and Technology, 62(3), p.300 - 307, 2025/03

https://doi.org/10.1080/00223131.2024.2427244

As nuclear facilities are dismantled in decommissioning, large amount of various waste is generated. Even more inconveniently, waste is radioactive due to neutron activation. Thus, the neutron capture cross-sections of nuclides targeted in decommissioning are required to evaluate the radioactivity produced. In this work, Fe nuclide was selected among objective nuclides for decommissioning, and its thermal-neutron capture cross-section was measured by a neutron activation method at the graphite thermal column of Kyoto University Research Reactor in 5-MW operation. The thermal-neutron capture cross-section was derived using s convention. The present work obtained 1.360.03 barns for the Fe(n,)Fe reaction. The present result supports the JENDL-5 evaluation within 2. If updated with currently recommended nuclear data, some of the reported past data would support the present result.

Relationships between protection and operational dosimetric quantities for external exposure to natural background radiation

Ulanowski, A.*; 佐藤 達彦; Petoussi-Henss, N.*; Balonov, M.*

Radiation and Environmental Biophysics, 64(1), p.105 - 115, 2025/03

https://doi.org/10.1007/s00411-025-01109-3

Protection and operational dosimetric quantities for human external exposure have been compared for situations of outdoor exposure to natural background radiation represented by gamma radiation of primordial and cosmogenic radionuclides and by radiations produced by the galactic cosmic rays in the earth atmosphere. Calculations were performed using the data from publications of ICRU and ICRP for global geographical grid of marine and terrestrial locations. Using modelled fluence spectra of natural cosmogenic and terrestrial background radiation, the ratios of the protection to operational quantities were calculated, demonstrating the effect of high-LET neutron component on the ratios of effective dose to absorbed dose or kerma in air. The influence of the neutron component was found to be stronger for high-altitude terrestrial locations and for terrestrial and marine locations at higher geographic latitudes. The computed ratios can be used for interpretation of the measured ambient dose rate data and calculation of effective doses in radiological protection tasks or assessment of public exposure to natural and anthropogenic sources of radiation.

Uncertainty quantification for severe-accident reactor modelling; Results and conclusions of the MUSA reactor applications work package

Brumm, S.*; Gabrielli, F.*; Sanchez Espinoza, V.*; Stakhanova, A.*; Groudev, P.*; Petrova, P.*; Vryashkova, P.*; Ou, P.*; Zhang, W.*; Malkhasyan, A.*; et al.

Annals of Nuclear Energy, 211, p.110962_1 - 110962_16, 2025/02

https://doi.org/10.1016/j.anucene.2024.110962

The completed Horizon-2020 project on "Management and Uncertainties of Severe Accidents (MUSA)" has reviewed uncertainty sources and Uncertainty Quantification methodology for the purpose of assessing Severe Accidents (SA). The key motivation of the project has been to bring the advantages of the Best Estimate Plus Uncertainty approach to the field of Severe Accident. The applications brought together a large group of participants that set out to apply uncertainty analysis (UA) within their field of SA modelling expertise, in particular reactor types, but also SA code used (ASTEC, MELCOR, etc.), uncertainty quantification tools used (DAKOTA, RAVEN, etc.), detailed accident scenarios, and in some cases SAM actions. This paper synthesizes the reactor-application work at the end of the project. Analyses of 23 partners are sorted into different categories, depending on whether their main goal is/are (i) uncertainty bands of simulation results; (ii) the understanding of dominating uncertainties in specific sub-models of the SA code; (iii) improving the understanding of specific accident scenarios, with or without the application of SAM actions; or, (iv) a demonstration of the tools used and developed, and of the capability to carry out an uncertainty analysis in the presence of the challenges faced. The partners' experiences made during the project have been evaluated and are presented as good practice recommendations. The paper ends with conclusions on the level of readiness of UA in SA modelling, on the determination of governing uncertainties, and on the analysis of SAM actions.

令和5年度大型計算機システム利用による研究成果報告集

システム計算科学センター 高性能計算技術利用推進室

JAEA-Review 2024-044, 121 Pages, 2025/01

JAEA-Review-2024-044.pdf:7.42MB

日本原子力研究開発機構では、原子力の総合的研究開発機関として原子力に係わるさまざまな分野の研究開発を行っており、これらの研究開発の多くにおいて計算科学技術が活用されている。日本原子力研究開発機構における計算科学技術を活用した研究開発の論文発表は、過去十数年にわたり、毎年度、全体の約2割を占めている。大型計算機システムはこの計算科学技術を支える重要なインフラとなっている。大型計算機システムは、第4期中長期計画にて重点化して取り組むとされた「安全性向上等の革新的技術開発によるカーボンニュートラルへの貢献」、「原子力科学技術に係る多様な研究開発の推進によるイノベーションの創出」、「東京電力福島第一原子力発電所事故の対処に係わる研究開発の推進」、「高レベル放射性廃棄物の処理処分に関する技術開発の着実な実施」、「原子力安全規制行政及び原子力防災に対する支援とそのための安全研究の推進」等といった研究開発活動に利用された。本報告は、令和5年度における大型計算機システムを利用した研究開発の成果を中心に、それを支える利用支援、利用実績、システムの概要等をまとめたものである。

Evolution of radionuclide transport and retardation processes in uplifting granitic rocks, Part 2; Modelling coupled processes in uplift scenarios

Metcalfe, R.*; Benbow, S. J.*; 川間 大介*; 舘 幸男

Science of the Total Environment, 958, p.177690_1 - 177690_17, 2025/01

https://doi.org/10.1016/j.scitotenv.2024.177690

花崗岩が隆起している条件を対象とした地層処分の安全評価においては、隆起による地質条件の変化とそれに伴う放射性核種の移行・遅延特性への影響を考慮する必要がある。このような地質環境の長期変遷を考慮した安全評価では、十分に現実的な数値モデルと適切なパラメータを適用する必要がある。しかしながら、隆起過程には、岩石特性や核種移行特性の変化などを含む複雑な連成現象が含まれるため、モデルの開発には困難を伴う。ここでは、いくつかの代表的な放射性核種を対象とした連成モデル解析を通じて、現実的で保守的なプロセスの概念化とモデルパラメータの設定を検討するための方法論を提示する。