Measurement of mechanical behavior of B-enriched MgB wire using a pulsed neutron source

町屋 修太郎*; 長村 光造*; 菱沼 良光*; 谷口 博康*; Harjo, S.; 川崎 卓郎

Quantum Beam Science (Internet), 7(4), p.34_1 - 34_17, 2023/10

https://doi.org/10.3390/qubs7040034

Measuring the actual strain on the MgB filaments are of paramount importance, since tensile stress and strain diminish the critical current. In this study, the strain measurement using neutron diffraction during tensile loading was established. We fabricated a MgB wire enriched with boron-11, an isotope having a smaller neutron absorption cross- section than natural boron, and succeeded in obtaining changes in the lattice constant under tensile loading through Rietveld analysis.

Work hardening behavior of dual phase copper-iron alloy at low temperature

山下 享介*; 古賀 紀光*; 川崎 卓郎; 諸岡 聡; 友野 翔平*; 梅澤 修*; Harjo, S.

Materials Science & Engineering A, 819, p.141509_1 - 141509_10, 2021/07

https://doi.org/10.1016/j.msea.2021.141509

In-situ neutron diffraction measurements were performed on a cold-rolled copper-iron (Cu-Fe) alloy during tensile tests at 293 K and 150 K. The roles of Cu and Fe on the deformation behavior of alloys were discussed and clarified. The strength and work-hardening rate of the alloy increased with decreasing test temperature. Furthermore, the phase stress of Fe increased considerably with decreasing test temperature; however, the response of this stress to the applied true stress exhibited no dependence on the temperature. The phase stresses of Cu changed only slightly with decreasing test temperature. However, the Cu phase stress response to the applied true stress increased with decreasing test temperature, indicating an increase in the work-hardening rate. The strengthening of Fe and the increase in the work-hardening of Cu contributed to an increase in the strength and work-hardening rate of the Cu-Fe alloy at low temperatures.

Neutron diffraction mapping measurement for Japanese nails in the ancient and present days

山下 享介; Harjo, S.; 梅澤 修*; 川崎 卓郎

JPS Conference Proceedings (Internet), 33, p.011063_1 - 011063_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011063

Japanese nails have been applied to various wooden building skeletons in Japanese temples and shrines over a period of one thousand years. Since most of Japanese nails in the ancient day are designated as an important cultural property, their destructive examinations can be hardly done. In order to discuss the material and its manufacturing process of the Japanese nails, we have done some experiments on both ancient and present Japanese nails. In this study, phase, texture and residual stress of the Japanese nails were investigated using neutron diffraction. Two types of Japanese nails were provided; one was an ancient nail obtained from Houryuji-temple; the other was a present nail forged by blacksmith. BCC iron peaks are identified in both. Although the cementite and ferrous oxide peaks are detected in the present nail, no cementite is detected in the ancient nail. The residual stresses of each nail were very low. The ferrite grains of each nail were randomly oriented.

Role of retained austenite in low alloy steel at low temperature monitored by neutron diffraction

山下 享介; 諸岡 聡; Harjo, S.; 川崎 卓郎; 古賀 紀光*; 梅澤 修*

Scripta Materialia, 177, p.6 - 10, 2020/03

https://doi.org/10.1016/j.scriptamat.2019.10.002

neutron diffraction measurements during tensile tests at low temperatures of a low alloy steel containing retained austenite have been performed. Evolutions of phase fractions and phase stresses were analyzed and discussed with the progress of deformation. The role of austenite in the steel during deformation at low temperatures was observed not to directly in the contribution to the strengths but in the improvement of the elongation by transformation of austenite to martensite -and in the increasing of the work-hardening rate by an increase in the phase fraction of martensite and the work hardening of martensite.

Mechanical-electromagnetic property of stainless sheet laminated BSCCO-2223 wires

長村 光造*; 町屋 修太郎*; 川崎 卓郎; Harjo, S.; 加藤 武志*; 小林 慎一*; 長部 吾郎*

Materials Research Express (Internet), 6(2), p.026001_1 - 026001_13, 2019/02

https://doi.org/10.1088/2053-1591/aaed0c

In order to elucidate the effect of applied tensile stress/strain on the critical current of DI-BSCCO-2223 wires, the critical current measurement and the tensile test were carried out at 77 K. Neutron diffraction measurements were also performed at 77 K to get direct information about the local strain exerted on the BSCCO superconducting filaments. It was reported that the critical current of BSCCO wires decreases linearly in a small range of tensile stress/strain and that the critical current returns reversibly on reducing the stress/strain. The gradual decrease of critical current was observed within the reversible region. When the tensile stress/strain increased beyond a characteristic value, the critical current decreased rapidly due to the brittle fracture of BSCCO filaments. It is proposed that the reversible stress/strain limit of critical current ( and ) can be defined experimentally as the 99% recovery stress ( and strain (. The reversible strain limit is proposed to consist mainly of three factors of pre-strain, thermal strain and tensile fracture strain of SC filaments themselves. The calculated relation between the and could well explain quantitatively the observed relation between 99% recovery stress and strain.

Eddy current-adjusted plasma shape reconstruction by Cauchy condition surface method on QUEST

中村 一男*; Jiang, Y.*; Liu, X.*; 御手洗 修*; 栗原 研一; 川俣 陽一; 末岡 通治; 長谷川 真*; 徳永 和俊*; 図子 秀樹*; et al.

Fusion Engineering and Design, 86(6-8), p.1080 - 1084, 2011/10

https://doi.org/10.1016/j.fusengdes.2011.04.045

CCS (Cauchy Condition Surface) method is a numerical approach to reproduce plasma shape, which has good precision in conventional tokamak. In order to apply it in plasma shape reproduction of ST (Spherical Tokamak), the calculation precision of the CCS method in CPD ( = 0.25 T, = 0.3 m, = 0.2 m) has been analyzed. The precision was confirmed also in ST and decided to be applied to QUEST ( = 0.25 T, = 0.68 m, = 0.40 m). In present stage from the magnetic measurement, it is known that the eddy current effect is large in QUEST experiment, and there are no special magnetic measurements for eddy current now, so some proper model should be selected to evaluate the eddy current effect. The eddy current density by not only CS (Center Solenoid) coil but also plasma current is calculated using EDDYCAL (JAEA), the eddy currents are taken as unknown variables and solved together with plasma shape reconstruction. The result shows that the CCS method with eddy current adjustment achieves stable, accurate reconstruction of plasma shape in application to QUEST.

Influence of crack initiation, propagation and coalescence on load in fatigue test at elevated temperature

Bubphachot, B.*; 渡部 修*; 川崎 信史; 笠原 直人

日本機械学会M&M2007材料力学カンファレンス講演論文集(CD-ROM), p.346 - 347, 2007/10

有孔平板の高温疲労におけるき裂の発生と進展がCCDカメラにより観察された。試験片はSUS304製であり、55Cの疲労試験を実施した。なお、有孔平板は孔径をパラメータとして製作している。き裂に発生を観察するため、各サイクルの画像データが取得された。試験結果は、応力再配分軌跡法(SRL法)とノイバー則によって比較検討された。

Creep-fatigue strength evaluation of perforated plate at elevated temperature using stress redistribution locus method

Bubphachopt, B.*; 渡部 修*; 川崎 信史; 笠原 直人

Proceedings of 2007 ASME Pressure Vessels and Piping Division Conference/8th International Conference on Creep and Fatigue at Elevated Temperatures (PVP 2007/CREEP-8) (CD-ROM), 9 Pages, 2007/07

有孔平板の高温疲労特性に対するクリープの影響を、応力再配分軌跡法(SRL法)を適用し検討した。試験温度は、550Cであり、SUS304製の有孔平板を用いてクリープ疲労試験が実施された。有孔平板は、孔数と孔径をパラメータとした。試験結果は、SRL法と時間消費則を用いて評価した。

A Methodology of structural analysis for nuclear power plant size of assembly

谷 正之; 中島 憲宏; 西田 明美; 鈴木 喜雄; 松原 仁; 新谷 文将; 櫛田 慶幸; 羽間 収; 近藤 誠; 川崎 幸三

Proceedings of Joint International Topical Meeting on Mathematics & Computations and Supercomputing in Nuclear Applications (M&C+SNA 2007) (CD-ROM), 12 Pages, 2007/04

The quakeproof analysis for an assembly structure such as a nuclear power plant should not be calculated as a piece of structure as existed structural analyses as do so, because of heterogeneity of each part in the functionality, which relates to the boundary condition. As well known that nuclear power plant consists of over ten million detailed parts, it takes lots of computational resources such as memory, disk space, and computational power to carry out its analysis. In order to achieve the assembly structure analysis, it is to give an efficient performance method, a treatable data handling method, and taking account the heterogeneity of each part in the functionality. The proposed method is to treat a power plant size assembly with its components. The components are handled by one by one to reduce the size of data at a operation, and to concern heterogeneity of each part.

HTTR(高温工学試験研究炉)の安全設計及び安全評価の考え方

飯垣 和彦; 七種 明雄; 澤畑 洋明; 篠崎 正幸; 栃尾 大輔; 本間 史隆; 橘 幸男; 伊与久 達夫; 川崎 幸三; 馬場 治*

JAEA-Review 2006-010, 90 Pages, 2006/07

JAEA-Review-2006-010.pdf:5.65MB

ガス炉は、原子力の開発初期からの長い歴史を持っており、高温ガス炉(HTGR)は、安全,効率,環境面から受容できかつ経済性から21世紀の工業用熱利用と発電に向けた高温のエネルギーを作り出す最終目標として期待されている。HTGRの革新的な設計には、受動的な安全装置の配置が試みられており、これらの原子炉の安全評価等については、おもに軽水炉用に策定されている現在の安全指針等を直接的にHTGRに適用できないこと等からの特別な配慮が必要となる。本報告では、試験研究炉HTTRでの安全設計安全評価についての変遷を調査し、軽水炉と異なる高温ガス炉の安全設計安全評価の特徴的な主な事項、これまでのHTTRの運転蓄積をもとに次期高温ガス炉の安全設計安全評価に反映すべく事項をとりまとめたものである。