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Predictive and inverse modeling of a radionuclide diffusion experiment in crystalline rock at ONKALO (Finland)

Soler, J. M.*; Kek$"a$l$"a$inen, P.*; Pulkkanen, V.-M.*; Moreno, L.*; Iraola, A.*; Trinchero, P.*; Hokr, M.*; $v{R}$$'i$ha, J.*; Havlov$'a$, V.*; Trpko$v{s}$ov$'a$, D.*; et al.

Nuclear Technology, 209(11), p.1765 - 1784, 2023/11

The REPRO-TDE test was performed at a depth of about 400 m in the ONKALO underground research facility in Finland. Synthetic groundwater containing radionuclide tracers (HTO, Cl-36, Na-22, Ba-133, Cs-134) was circulated for about four years in a packed-off interval of the injection borehole. Tracer activities were additionally monitored in two observation boreholes. The test was the subject of a modelling exercise by the SKB GWFTS Task Force. Eleven teams participated in the exercise, using different model concepts and approaches. Predictive model calculations were based on laboratory-based information concerning porosities, diffusion coefficients and sorption partition coefficients. After the experimental results were made available, the teams were able to revise their models to reproduce the observations. General conclusions from these back-analysis calculations include the need for reduced effective diffusion coefficients for Cl-36 compared to those applicable to HTO (anion exclusion), the need to implement weaker sorption for Na-22, compared to results from laboratory batch-sorption experiments, and the observation of large differences between the theoretical initial concentrations for the strongly-sorbing Ba-133 and Cs-134 and the first measured values a few hours after tracer injection. Different teams applied different concepts, concerning mainly the implementation of isotropic vs. anisotropic diffusion, or the possible existence of Borehole Disturbed Zones around the different boreholes. The role of microstructure was also addressed in two of the models.


First observation of $$^{28}$$O

近藤 洋介*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; 馬場 秀忠*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.

Nature, 620(7976), p.965 - 970, 2023/08



High-temperature creep properties of 9Cr-ODS tempered martensitic steel and quantitative correlation with its nanometer-scale structure

大塚 智史; 静川 裕太; 丹野 敬嗣; 今川 裕也; 橋立 竜太; 矢野 康英; 鬼澤 高志; 皆藤 威二; 大沼 正人*; 光原 昌寿*; et al.

Journal of Nuclear Science and Technology, 60(3), p.288 - 298, 2023/03

 被引用回数:2 パーセンタイル:82.38(Nuclear Science & Technology)



Magnetic ground state of YbCo$$_2$$Zn$$_{20}$$ probed by muon spin relaxation

髭本 亘; 佐藤 一彦*; 伊藤 孝; 大石 一城*; 才賀 裕太*; 小坂 昌史*; 松林 和幸*; 上床 美也*

Journal of Physics; Conference Series, 2462, p.012039_1 - 012039_5, 2023/03



Present status of J-PARC MUSE

下村 浩一郎*; 幸田 章宏*; Pant, A. D.*; 名取 寛顕*; 藤森 寛*; 梅垣 いづみ*; 中村 惇平*; 反保 元伸*; 河村 成肇*; 手島 菜月*; et al.

Journal of Physics; Conference Series, 2462, p.012033_1 - 012033_5, 2023/03

At J-PARC MUSE, since the $$mu$$SR2017 conference and up to FY2022, there have been several new developments at the facility, including the completion of a new experimental area S2 at the surface muon beamline S-line and the first muon beam extraction to the H1 area in the H-line, mainly to carry out high-statistics fundamental physics experiments. Several new studies are also underway, such as applying negative muon non-destructive elemental analysis to the analysis of samples returned from the asteroid Ryugu in the D2 area of the D-line. This paper reports on the latest status of MUSE.


Study of the $$N=32$$ and $$N=34$$ shell gap for Ti and V by the first high-precision multireflection time-of-flight mass measurements at BigRIPS-SLOWRI

飯村 俊*; Rosenbusch, M.*; 高峰 愛子*; 角田 佑介*; 和田 道治*; Chen, S.*; Hou, D. S.*; Xian, W.*; 石山 博恒*; Yan, S.*; et al.

Physical Review Letters, 130(1), p.012501_1 - 012501_6, 2023/01

 被引用回数:1 パーセンタイル:95.37(Physics, Multidisciplinary)

The atomic masses of $$^{55}$$Sc, $$^{56,58}$$Ti, and $$^{56-59}$$V have been determined using the high-precision multireflection time-of-flight technique. The radioisotopes have been produced at RIKEN's Radioactive Isotope Beam Factory (RIBF) and delivered to the novel designed gas cell and multireflection system, which has been recently commissioned downstream of the ZeroDegree spectrometer following the BigRIPS separator. For $$^{56,58}$$Ti and $$^{56-59}$$V, the mass uncertainties have been reduced down to the order of 10 keV, shedding new light on the $$N=34$$ shell effect in Ti and V isotopes by the first high-precision mass measurements of the critical species $$^{58}$$Ti and $$^{59}$$V. With the new precision achieved, we reveal the nonexistence of the $$N=34$$ empirical two-neutron shell gaps for Ti and V, and the enhanced energy gap above the occupied $$nu$$p$$_{3/2}$$ orbit is identified as a feature unique to Ca. We perform new Monte Carlo shell model calculations including the $$nu$$d$$_{5/2}$$ and $$nu$$g$$_{9/2}$$ orbits and compare the results with conventional shell model calculations, which exclude the $$nu$$g$$_{9/2}$$ and the $$nu$$d$$_{5/2}$$ orbits. The comparison indicates that the shell gap reduction in Ti is related to a partial occupation of the higher orbitals for the outer two valence neutrons at $$N = 34$$.


New $$K$$ isomers in $$^{248}$$Cf

Orlandi, R.; 牧井 宏之; 西尾 勝久; 廣瀬 健太郎; 浅井 雅人; 塚田 和明; 佐藤 哲也; 伊藤 由太; 洲嵜 ふみ; 永目 諭一郎*; et al.

Physical Review C, 106(6), p.064301_1 - 064301_11, 2022/12

 被引用回数:0 パーセンタイル:0.02(Physics, Nuclear)

The nuclear structure of $$^{248}$$Cf produced by the $$^{18}$$O+$$^{249}$$Cf multinucleon transfer reaction was investigated using $$gamma$$-ray spectroscopy. Analysis of the $$gamma$$-ray spectrum of $$^{248}$$Cf revealed the presence of multiple long-lived (isomeric) excited states at low excitation energies. The energies and half-lives of the isomers contain information on the proton and neutron orbits in the heavy-element region and the deformation of atomic nuclei, and are important data to predict the properties of nuclei in the "island of stability".


Sodium-cooled Fast Reactors

大島 宏之; 森下 正樹*; 相澤 康介; 安藤 勝訓; 芦田 貴志; 近澤 佳隆; 堂田 哲広; 江沼 康弘; 江連 俊樹; 深野 義隆; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

ナトリウム冷却高速炉(SFR: Sodium-cooled Fast Reactor)の歴史や、利点、課題を踏まえた安全性、設計、運用、メンテナンスなどについて解説する。AIを利用した設計手法など、SFRの実用化に向けた設計や研究開発についても述べる。


The Multiaxial creep-fatigue failure mechanism of Mod. 9Cr-1Mo steel under non-proportional loading; Effect of strain energy on failure lives

小川 文男*; 中山 雄太*; 旭吉 雅健*; 橋立 竜太; 若井 隆純; 伊藤 隆基*

Transactions of the Indian National Academy of Engineering (Internet), 7(2), p.549 - 564, 2022/06



Time-resolved 3D visualization of liquid jet breakup and impingement behavior in a shallow liquid pool

木村 郁仁*; 山村 聡太*; 藤原 広太*; 吉田 啓之; 齋藤 慎平*; 金子 暁子*; 阿部 豊*

Nuclear Engineering and Design, 389, p.111660_1 - 111660_11, 2022/04

 被引用回数:3 パーセンタイル:73.56(Nuclear Science & Technology)

A new three-dimensional laser-induced fluorescent (3D-LIF) technology to obtain the hydrodynamic behavior of liquid jets in a shallow pool were developed. In this technology, firstly, a refractive index matching was applied to acquire a clear cross-sectional image. Secondly, a series of cross-sectional images was obtained by using a high-speed galvanometer scanner. Finally, to evaluate the unsteady 3D interface shape of liquid jet, a method was developed to reconstruct 3D shapes from the series of cross-sectional images obtained using the 3D-LIF method. The spatial and temporal resolutions of measurement were 4.7 $$times$$ 4.7 $$times$$ 1.0 lines/mm and 25 $$mu$$s, respectively. The shape of a 3D liquid jet in a liquid pool and its impingement, spreading and atomization behavior were reconstructed using the proposed method, successfully. The behaviors of atomized particles detached from the jet were obtained by applying data processing techniques. Diameters distribution and position of atomized droplets after detachment were estimated from the results.


A Storm-induced flood and associated nearshore dispersal of the river-derived suspended $$^{137}$$Cs

内山 雄介*; 徳永 夏樹*; 東 晃平*; 上平 雄基; 津旨 大輔*; 岩崎 理樹*; 山田 正俊*; 立田 穣*; 石丸 隆*; 伊藤 友加里*; et al.

Science of the Total Environment, 816, p.151573_1 - 151573_13, 2022/04

 被引用回数:5 パーセンタイル:74.25(Environmental Sciences)



"Live-autoradiography" technique reveals genetic variation in the rate of Fe uptake by barley cultivars

樋口 恭子*; 栗田 圭輔; 酒井 卓郎; 鈴井 伸郎*; 佐々木 実莉*; 香取 摩耶*; 若林 優奈*; 間嶋 勇太*; 齋藤 彰宏*; 大山 卓爾*; et al.

Plants (Internet), 11(6), p.817_1 - 817_11, 2022/03

 被引用回数:2 パーセンタイル:43.33(Plant Sciences)




矢野 康英; 橋立 竜太; 丹野 敬嗣; 今川 裕也; 加藤 章一; 鬼澤 高志; 伊藤 主税; 上羽 智之; 大塚 智史; 皆藤 威二

JAEA-Data/Code 2021-015, 64 Pages, 2022/01


安全性・経済性に優れ、放射性廃棄物の減容化・有害度の低減に貢献する高速増殖炉サイクルシステムの実用化の観点から、燃料の高燃焼度化が求められており、これに対応した被覆管材料の開発が必要不可欠である。この高燃焼度達成のための被覆管材料には、耐照射スエリング性能及び高温強度特性に優れた酸化物分散強化(Oxide Dispersion Strengthened; ODS)フェライト鋼の研究開発を実施している。ODSフェライト鋼を燃料被覆管として適用するためには、材料強度基準整備が重要であり、そのためのクリープ強度データ等の各種強度データ取得を実施している。本研究では、材料強度基準整備に資することを目的に、これまで得られた知見・検討結果に基づき、9Cr-ODS鋼被覆管の引張強度とクリープ強度特性について評価を行った。9Cr-ODS鋼は相変態温度を持つことから、母相の相状態が変化しない850$$^{circ}$$C以下と事故時を想定したそれ以上の温度域に分けて評価を行った。


Evaluation report of Task 9C based on comparisons and analyses of modelling results for the ONKALO REPRO-TDE experiment

Soler, J. M.*; Kek$"a$l$"a$inen, P.*; Pulkkanen, V.-M.*; Moreno, L.*; Iraola, A.*; Trinchero, P.*; Hokr, M.*; $v{R}$$'i$ha, J.*; Havlov$'a$, V.*; Trpko$v{s}$ov$'a$, D.*; et al.

SKB TR-21-09, 204 Pages, 2021/11

Task 9C of the SKB Task Force on Modelling of Groundwater Flow and Transport of Solutes (Task Force GWFTS) was the third subtask within Task 9 and focused on (1) predictive and (2) back-analysis modelling of experimental results from the REPRO-TDE in situ diffusion experiment. The test was performed at a depth of about 400 m in the ONKALO underground research facility in Finland. Synthetic groundwater containing radionuclide tracers (HTO, Cl-36, Na-22, Ba-133, Cs-134) was circulated for about four years in a packed-off interval of the so-called injection borehole. Tracer activities were additionally monitored in two observation boreholes arranged as a right-angled triangle and located at about 0.1 m wall-to-wall from the injection borehole. Eleven modelling teams participated in the modelling exercise, using different model concepts and approaches. Three main types of models were applied: (1) An analytical solution to the diffusion-retention equations, (2) continuum-porous-medium-type numerical models, and (3) microstructure-based models. The predictive model calculations were based on laboratory-based information concerning porosities, diffusion coefficients and sorption partition coefficients available in the task description. Microstructural characterisation of rock samples was also available and used by the teams using microstructure-based models.


The $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe cross section from the surrogate ratio method and its effect on the $$^{60}$$Fe nucleosynthesis

Yan, S. Q.*; Li, X. Y.*; 西尾 勝久; Lugaro, M.*; Li, Z. H.*; 牧井 宏之; Pignatari, M.*; Wang, Y. B.*; Orlandi, R.; 廣瀬 健太郎; et al.

Astrophysical Journal, 919(2), p.84_1 - 84_7, 2021/10

 被引用回数:1 パーセンタイル:9.7(Astronomy & Astrophysics)

The long-lived $$^{60}$$Fe (with a half-life of 2.62 Myr) is a crucial diagnostic of active nucleosynthesis in the Milky Way galaxy and in supernovae near the solar system. The neutron-capture reaction $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe on $$^{59}$$Fe (half-life=44.5 days) is the key reaction for the production of $$^{60}$$Fe in massive stars. This reaction cross section has been previously constrained by the Coulomb dissociation experiment, which offered partial constraint on the E1 $$gamma$$-ray strength function but a negligible constraint on the M1 and E2 components. In this work, for the first time, we use the surrogate ratio method to experimentally determine the $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe cross sections in which all the components are included. We derived a Maxwellian-averaged cross section of 27.5$$pm$$3.5 mb at $$kT$$ = 30 keV and 13.4$$pm$$1.7 mb at $$kT$$ = 90 keV, roughly 10%-20% higher than previous estimates. We analyzed the impact of our new reaction rates in nucleosynthesis models of massive stars and found that uncertainties in the production of $$^{60}$$Fe from the $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe rate are at most 25$$%$$. We conclude that stellar physics uncertainties now play a major role in the accurate evaluation of the stellar production of $$^{60}$$Fe.


Chiral-spin rotation of non-collinear antiferromagnet by spin-orbit torque

竹内 祐太郎*; 山根 結太*; Yoon, J.-Y.*; 伊藤 隆一*; 陣内 佛霖*; 金井 駿*; 家田 淳一; 深見 俊輔*; 大野 英男*

Nature Materials, 20(10), p.1364 - 1370, 2021/10

 被引用回数:62 パーセンタイル:98.63(Chemistry, Physical)

Electrical manipulation of magnetic materials by current-induced spin torque constitutes the basis of spintronics. Recent studies have demonstrated electrical controls of ferromagnets and collinear antiferromagnets by spin-orbit torque (SOT). Here we show an unconventional response to SOT of a non-collinear antiferromagnet, which has recently attracted great attention owing to large anomalous Hall effect despite vanishingly small net magnetization. In heterostructures with epitaxial non-collinear antiferromagnet Mn$$_3$$Sn, we observe a characteristic fluctuation of Hall resistance, which is attributed to a persistent rotation of chiral-spin structure of Mn$$_3$$Sn driven by SOT. We find that level of the fluctuation that varies with sample size represents the number of magnetic domains of Mn$$_{3}$$Sn. In addition, Mn$$_3$$Sn thickness dependence of critical current reveals that SOT generated by small current density below 20 MA cm$$^{-2}$$ effectively acts on the chiral-spin structure even in thick Mn$$_3$$Sn above 20 nm. The results provide unprecedented pathways of electrical manipulation of magnetic materials, offering new-concept spintronics devices with unconventional functionalities and low-power consumption.


Chemical characterization of a volatile dubnium compound, DbOCl$$_3$$

Chiera, N. M.*; 佐藤 哲也; Eichler, R.*; 富塚 知博; 浅井 雅人; 安達 サディア*; Dressler, R.*; 廣瀬 健太郎; 井上 浩樹*; 伊藤 由太; et al.

Angewandte Chemie; International Edition, 60(33), p.17871 - 17874, 2021/08

 被引用回数:2 パーセンタイル:16.39(Chemistry, Multidisciplinary)

等温ガスクロマトグラフ法を用いて、105番元素ドブニウム(Db)の単一原子を対象として、揮発性オキシ塩化物を合成し、化学的性質を調べた。同一条件下で同族元素ニオブおよびタンタルの揮発性と比較したところ、NbOCl$$_3 > $$ TaOCl$$_3 geq$$ DbOCl$$_3$$の関係が得られた。これはDb分子中の共有結合性が周期表からの予想よりも強くなっているためと考えられる。本成果により、超アクチノイド元素の化学的性質に関する理論計算に対する信頼できる実験データを与えることができた。


Evaluation of multiaxial low cycle creep-fatigue life for Mod.9Cr-1Mo steel under non-proportional loading

中山 雄太*; 小川 文男*; 旭吉 雅健*; 橋立 竜太; 若井 隆純; 伊藤 隆基*

ISIJ International, 61(8), p.2299 - 2304, 2021/08

 被引用回数:3 パーセンタイル:36.78(Metallurgy & Metallurgical Engineering)



Rabi-oscillation spectroscopy of the hyperfine structure of muonium atoms

西村 昇一郎*; 鳥居 寛之*; 深尾 祥紀*; 伊藤 孝; 岩崎 雅彦*; 神田 聡太郎*; 川越 清以*; Kawall, D.*; 河村 成肇*; 黒澤 宣之*; et al.

Physical Review A, 104(2), p.L020801_1 - L020801_6, 2021/08

 被引用回数:12 パーセンタイル:85.05(Optics)

As a method to determine the resonance frequency, Rabi-oscillation spectroscopy has been developed. In contrast to conventional spectroscopy which draws the resonance curve, Rabi-oscillation spectroscopy fits the time evolution of the Rabi oscillation. By selecting the optimized frequency, it is shown that the precision is twice as good as conventional spectroscopy with a frequency sweep. Furthermore, the data under different conditions can be treated in a unified manner, allowing more efficient measurements for systems consisting of a limited number of short-lived particles produced by accelerators such as muons. We have developed a fitting function that takes into account the spatial distribution of muonium and the spatial distribution of the microwave intensity to apply this method to ground-state muonium hyperfine structure measurements at zero field. It was applied to the actual measurement data, and the resonance frequencies were determined under various conditions. The result of our analysis gives $$nu_{rm HFS}$$ = 4 463 301.61 $$pm$$ 0.71 kHz.


Droplet-entrainment phenomena affected by interfacial behavior of a high-speed gas jet into a liquid pool

齋藤 雅史*; 金子 暁子*; 阿部 豊*; 内堀 昭寛; 栗原 成計; 高田 孝*; 大島 宏之

Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 7 Pages, 2021/08


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