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C-stainless steel composites using the improved MPS methodAhmed, Z.*; Wu, S.*; Sharma, A.*; Kumar, R.*; 山野 秀将; Pellegrini, M.*; 横山 諒*; 岡本 孝司*
International Journal of Heat and Mass Transfer, 250, p.127343_1 - 127343_17, 2025/11
The study aims to measure boron concentration through the unidirectional diffusion of boron within the stainless steel (SS) layers while evaluating the updated model ability to replicate melt relocation behavior and geometry. In the current MPS simulations, one scenario employed dummy walls as heat sources, while another scenario used SS surface particles as heat sources to avoid interference with the melt flow as it reached the bottom of the specimen.
和田 裕貴; 柴本 泰照; 日引 俊詞*
International Journal of Heat and Mass Transfer, 249, p.127219_1 - 127219_16, 2025/10
Two saturated boiling heat transfer correlations for downward flows in vertical circular pipes depending on wall superheat or wall heat flux as input parameters were developed based on a heat transfer experimental database. Owing to the absence of heat transfer correlations specifically developed for downward flows, existing heat transfer correlations for different flow directions were evaluated to determine their applicability to predicting the downward flow heat transfer coefficient. The results revealed that even the most accurate correlation showed a mean absolute percentage error (MAPE) of 66.5%, highlighting the need for improving predictive performance. In response, the downward flow heat transfer correlation was modeled by integrating a nucleate boiling heat transfer term and a forced convection heat transfer term. The Dong-Hibiki correlation, a two-component, two-phase heat transfer correlation for downward flows, was adopted for the forced convection heat transfer term. The Forster-Zuber correlation, developed as a wall superheat function, and the Cooper correlation, developed as a wall heat flux function, were used for the nucleate boiling term to develop the heat transfer correlations where either wall superheat or wall heat flux is known. Notably, the Dong-Hibiki correlation has been validated over a wide range of experimental conditions. A correction factor was applied to the nucleate boiling term to address errors caused by applying Foster-Zuber and Cooper correlations to downward flows. The two developed correlations achieved an MAPE value of approximately 20%, representing an improvement of roughly 40% over existing correlations of heat transfer coefficients.
青木 健; 清水 厚志; 石井 克典; 守田 圭介; 水田 直紀; 倉林 薫; 安田 貴則; 野口 弘喜; 野本 恭信; 飯垣 和彦; et al.
Annals of Nuclear Energy, 220, p.111503_1 - 111503_7, 2025/09
被引用回数：0原子力機構は、核熱により水素を製造する原子力水素製造システムの接続技術を確立するため、HTTR-熱利用試験プロジェクトを開始し、その許認可に向けた安全設計及び安全解析を行っている。本研究では、原子力水素製造システムの適用法令及び設計基準の区分の候補の優劣を評価するための相対評価手法を提案し、それをHTTR-熱利用試験施設に適用した。評価の結果、高圧ガス保安法を熱利用試験施設(水素製造施設)に適用し、高圧ガス保安法に基づく設計基準を水蒸気改質器に適用する候補は、いずれの指標においても最下位とならず、最も優れた候補として提案された。
相馬 秀; 石垣 将宏*; 柴本 泰照
Annals of Nuclear Energy, 219, p.111455_1 - 111455_12, 2025/09
被引用回数：0 パーセンタイル：0.00(Nuclear Science & Technology)Containment venting is one of the accident mitigation measures during severe accidents in nuclear power plants for preventing overpressure failure of the containment vessels. Because of the capability of releasing hydrogen generated in the containment vessel, the hydrogen risk can be also reduced. In this study, we conducted experiments with the large-scale test facility CIGMA to investigate the light gas transport during the venting action, mainly focusing on the effect of sump water boiling caused by the vent. The CIGMA test vessel initially pressurized by steam, air, and helium (hydrogen simulant) that formed a helium-rich density stratification was depressurized with and without sump water, with different venting flow rates, and at different venting positions. As the sump water became a steam source due to flash boiling, the helium stratification was diluted and the venting time increased twofold compared to the case without sump water, which significantly affected the amount of helium discharged to the atmosphere. Especially for the high venting flow rate condition, the amount of helium remaining in the vessel at the end of depressurization was half that of the case without sump water. Lowering the venting position from within the initial stratification to 3 m below its interface led to a threefold increase in the amount of helium remaining at the same low pressure, because of the longer time until the helium-rich stratification reached the venting position.
Yildirim, A. C.*; Mei, H.*; 戸田 賀奈子*; 青柳 登; 斉藤 拓巳*
Applied Clay Science, 274, p.107853_1 - 107853_9, 2025/09
被引用回数：0Metakaolin-based geopolymers (MKGPs) are ceramic-like materials used for nuclear waste stabilization. Therefore, understanding the sorption of ions on MKGPs is crucial where the cation exchange is considered as the main mechanism, yet the studies based on pH are limited. Thus, this study evaluates the effect of pH on the sorption mechanism of Eu(III) onto Na- and K-MKGPs. Here, time-resolved laser fluorescence spectroscopy (TRLFS) combined with parallel factor analysis, TRLFS in mixed D
O/HO matrices, and extended X-ray absorption fine structure analysis. Eu(III) predominantly forms surface complexes with both MKGPs in the pH range of 4 
11 at the open air environment, where three distinct surface species were identified at different pH values. The Eu(III) sorption mechanisms of both MKGPs are similar, involving ternary edge-sharing bidentate or monodentate inner-sphere surface complexation of Eu(III) with MKGP and silicate ions released from the MKGP up to pH 8, followed by the precipitation of europium tri-hydroxide within the pores of MKGP. The insights gained from this studywill enhance the knowledge on MKGP for pollutant immobilization, thereby mitigating the spread of contaminants in the environment and expanding the potential application areas.
Wang, Z.; 松本 俊慶; 柴本 泰照; Duan, G.*
Journal of Computational Physics, 537, p.114072_1 - 114072_29, 2025/09
In this study, we develop a novel sharp surface tension (SST) model for multiphase particle methods. Our approach integrates surface tension directly into pressure computation, enabling precise representation of pressure discontinuities across interfaces and effectively mitigating parasitic currents. In addition, to improve curvature accuracy, particularly in scenarios involving topological changes, a co-directional scheme is proposed to faithfully consider interfacial normal vectors. Furthermore, we reconstruct the interfacial particle shifting scheme to separately address tangential, normal, and repulsive components, effectively suppressing the common problem of interface particle mixing in multiphase particle methods. The effectiveness and reliability are rigorously validated through a series of numerical tests, including the Rayleigh-Taylor instability, curvature verification, droplet deformation and coalescence, as well as bubble rising and coalescence. The results demonstrate the superior accuracy and robustness of the proposed method, marking a significant advancement in simulations of multiphase flow with surface tension.
Mn
N and Fe
Co
N filmsYin, W.*; 伊藤 啓太*; 坪和 優佑*; 辻川 雅人*; 白井 正文*; 梅津 理恵*; 高梨 弘毅
Journal of Magnetism and Magnetic Materials, 628, p.173157_1 - 173157_8, 2025/09
被引用回数：0FeN exhibits a large anomalous Nernst effect (ANE), which motivates a systematic study of enhancing the anomalous Nernst coefficient (S
) by modulating its electronic and magnetic structures. In this study, Mn and Co substitution effects for Fe in FeN on S
were investigated. FeMnN and FeCoN films in wide ranges of x and y were grown epitaxially on MgO(001) and (LaAlO
)
(SrTaAlO
)
(001) substrates, respectively, using molecular beam epitaxy. The S value of the FeN film is suppressed by substituting Fe with Mn or Co. By measuring the ANE, Seebeck effect, and anomalous Hall effect, the transverse thermoelectric conductivity (
) was evaluated. The composition dependence of S was dominated by the change of for both FeMnN and FeCoN films. First-principles calculations were conducted for the transverse electric conductivity (
) and of FeN and Fe
Co
N, and large leading to large S was predicted in FeCoN.
Rizaal, M.; 中島 邦久; 鈴木 恵理子; 三輪 周平
Annals of Nuclear Energy, 218, p.111433_1 - 111433_10, 2025/08
被引用回数：0 パーセンタイル：0.00(Nuclear Science & Technology)The release of iodine in a case of severe nuclear accident is directly linked to short-term radiological consequences. This concern raises issues in understanding the chemical forms of the transported iodine to devise proper accident management measures/strategies. In contributing to such efforts, this work presents experimental and theoretical approaches to defining the impact of molybdenum as a semi-volatile fission product toward iodine speciation in the gas phase. Given humid atmospheric conditions with different oxygen potentials, the interactions were revealed through the reaction products consisting of both gas and aerosols upon their transport and condensation in the temperature range of 1150-450 K. Through thermodynamic equilibrium calculations where new thermodynamic data of cesium molybdates have been incorporated, the experimental observation was reproduced, hence general interaction mechanism was proposed in this work.
(Al, Zn)
Approximant crystal; Influence of chemical disorder清水 一行*; 山口 正剛; 赤丸 悟士*; 西村 克彦*; 阿部 李音*; 佐々木 泰祐*; Wang, Y.*; 戸田 裕之*
Scripta Materialia, 265, p.116730_1 - 116730_7, 2025/08
被引用回数：0The approximant crystal Mg(Al, Zn) (T-phase in Al-Zn-Mg alloys) holds the potential for enhancing both strength and hydrogen embrittlement resistance in aluminum alloys when present as nano-precipitates. Our previous computational exploration indicated strong hydrogen trapping but neglected the inherent chemical disorder of this approximant crystal. This study revisits hydrogen trapping in Mg(Al, Zn), directly including chemical disorder via special quasirandom structures. Density functional theory calculations reveal that, while chemical disorder introduces variations in trapping energies, the overall trend of strong trapping persists. Tetrahedral sites coordinated by Mg atoms exhibit particularly strong trapping, with smaller tetrahedral volumes correlating with stronger trapping due to enhanced Mg-H interactions. Multiple hydrogen occupation of these sites is also calculated, resulting in high hydrogen densities. Experimental validation using thermal desorption spectroscopy on a bulk Mg(Al, Zn) sample confirms hydrogen trapping, reinforcing the potential of this phase for designing advanced, hydrogen-resistant aluminum alloys.
荒木 祥平; 會澤 栄寿; 村上 貴彦; 新垣 優; 多田 裕太; 神川 豊; 長谷川 健太; 吉川 智輝; 住谷 正人; 関 真和; et al.
Annals of Nuclear Energy, 217, p.111323_1 - 111323_8, 2025/07
被引用回数：0 パーセンタイル：0.00(Nuclear Science & Technology)原子力機構では、臨界集合体STACYを均質溶液体系から非均質軽水減速体系へと更新した。STACY更新炉においても最大熱出力は200Wと定められており、熱出力校正は運転を行う上で重要である。熱出力測定においては、溶液系STACYで用いていたFPの分析による熱出力の評価が適応できなかったため、放射化法をベースとする実験データと数値計算を組み合わせて出力を評価する手法をSTACY更新炉の体系に適応し、測定を実施した。測定データを基に出力校正を実施した結果、校正後の指示値は放射化法による測定結果と3%以内で一致した。
望月 陽人; 松井 裕哉; 中山 雅; 坂本 亮*; 柴田 真仁*; 本島 貴之*; 城 まゆみ*
Case Studies in Construction Materials, 22, p.e04648_1 - e04648_20, 2025/07
被引用回数：0放射性廃棄物の地層処分で使用される低アルカリ性セメントは、長期にわたる処分場の操業期間中に大気中の二酸化炭素による炭酸化や地下水との接触によってその特性が変化する可能性がある。本研究では、フライアッシュとシリカヒュームを混合した低アルカリ性セメント(HFSC)を用いた吹付けコンクリートの化学的特性、微細構造ならびに輸送特性に対して大気中での炭酸化および地下水との接触が与える影響を、幌延の地下研究施設において16年間にわたり調査した。HFSC吹付けコンクリートの炭酸化領域と溶出領域のいずれにおいても、直径約300nm未満の細孔の毛細管空隙率が増加し、全空隙率は非変質領域よりも高くなった。これらの空隙構造の変化は、ケイ酸カルシウム水和物(C-S-H)の脱灰とエトリンガイトの分解に関連していると考えられる。このような変化は、OPC吹付けコンクリートの変質領域では軽微であったことから、本研究の調査条件下において、HFSC吹付けコンクリートは炭酸化や地下水溶出に対する抵抗性が相対的に低いことが示された。しかしながら、HFSCの透水係数は、地層処分に用いられる低pHセメントに求められる機能要件を満たす程度に低かった。
相馬 康孝; 小松 篤史; 加治 芳行; 山本 正弘*; 五十嵐 誉廣
Corrosion Science, 251, p.112897_1 - 112897_15, 2025/07
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)高温水中(288
C)におけるステンレス鋼のすき間内部への酸素侵入に関する実験およびモデリング研究を実施した。すき間内への酸素侵入の限界距離
は、酸素濃度、すき間幅、浸漬時間に関わらず、すき間開口部からの距離dがそれ以上の数値になる場合、主要表面酸化物組成が(ヘマタイト
マグネタイトに)変化する位置として定義することができた。その場測定により、付近での電気伝導度の増加が確認され、これは酸素濃度差電池によるイオン濃縮を示した。は、すき間幅、酸素濃度、浸漬時間の増加に伴って拡大した。モデル計算の結果、酸化膜の成長によってステンレス鋼金属のアノード溶解が抑制され、対応する酸素のカソード還元消費速度が低下することで、時間とともに酸素の侵入が進行することが示唆された。
Johansen, M. P.*; Gwynn, J. P.*; Carpenter, J. G.*; Charmasson, S.*; 森 愛理; Orr, B.*; Simon-Cornu, M.*; Osvath, I.*; McGinnity, P.*
Journal of Environmental Radioactivity, 287, p.107706_1 - 107706_8, 2025/07
被引用回数：0Radiological ingestion doses from eating seafood are regularly evaluated near coastal nuclear facilities, following accidents/events and frequently in national studies worldwide. However, a recent global review found that published seafood doses varied greatly depending on which radionuclides were selected for evaluation and that there has been a tendency to omit important radionuclides or focus on less significant ones. This indicates a need for clear guidance on which radionuclides to prioritise in such studies. Here, we use worldwide data for 16 key radionuclides contributing to typical background seafood ingestion dose. We account for the loss of radionuclides during cooking and the radioactive decay of the short-lived 
Po. Results indicate that for the typical world consumer, naturally-occurring radionuclides account for 
99% of the total seafood ingestion dose, of which about 84% comes from Po and 8% from Pb. About 5% comes from 
Ra, a far greater proportion than the more frequently-assessed 
Ra (
1%). Other Th- and U-series radionuclides provide far lower contributions (0.07%-0.70%), while 
C provides about 0.09%. In comparison, the contribution to total seafood ingestion dose from background anthropogenic radionuclides is 1%, with 
Cs contributing most (0.08%) and 
Sr, 
Tc, 
Ag and 
Pu adding a further 0.05% together. These percentage contributions to dose can vary somewhat depending on consumption patterns (e.g., differing proportions of fish, bivalves, etc.). However, Po is the dominant contributor irrespective of country-specific diets or restricted diet scenarios (fish-only, seaweed-only, etc.). Study results provide new guidance to improve the design, interpretation and communication of seafood ingestion dose assessments.
Gu, G. H.*; Jeong, S. G.*; Heo, Y.-U.*; Harjo, S.; Gong, W.; Cho, J.*; Kim, H. S.*; 他4名*
Journal of Materials Science & Technology, 223, p.308 - 324, 2025/07
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)Face-centered cubic (FCC) equi-atomic multi-principal element alloys (MPEAs) exhibit excellent mechanical properties from cryogenic to room temperatures. At room temperature, deformation is dominated by dislocation slip, while at cryogenic temperatures (CTs), reduced stacking fault energy enhances strain hardening with twinning. This study uses in-situ neutron diffraction to analyze the temperature-dependent deformation behavior of Al
(CoNiV)
, a dual-phase (FCC/BCC) medium-entropy alloy (MEA). At liquid nitrogen temperature (LNT), deformation twinning in the FCC matrix leads to additional strain hardening through the dynamic Hall-Petch effect, giving the appearance of improved strengthening at LNT. In contrast, BCC precipitates show dislocation slip at both 77 K and 298 K, with temperature-dependent lattice friction stress playing a significant role in strengthening. The study enhances understanding of deformation behaviors and provides insights for future alloy design.
石飛 尊之
Journal of the Physical Society of Japan, 94(7), p.075001_1 - 075001_2, 2025/07
We show that superzone gap formation-phenomena usually attributed to antiferroic ordering-can also arise from ferroic orders in materials featuring sublattice structures. Through an analysis of a 
-orbital tight-binding model on a zigzag chain, we reveal that ferroquadrupolar or ferromagnetic ordering, as well as external magnetic fields, can generate a Su-Schrieffer-Heeger-type gap.
久保 勝規
Journal of the Physical Society of Japan, 94(7), p.074701_1 - 074701_5, 2025/07
Surface states of a tight-binding model with nearest-neighbor hopping on a diamond lattice of finite thickness are investigated. We consider systems with (001), (110), and (111) surfaces. Even if the surface direction is fixed, there is freedom to choose the surface structure due to the two-sublattice nature of a diamond lattice. The existence of surface states is governed by the topology of the matrix elements of the bulk Hamiltonian. In this sense, the existence of surface states is determined by the bulk Hamiltonian. However, the matrix elements depend on the choice of the unit cell, which should be chosen to conform to the surface structure. Thus, the surface states depend on the surface structure. We find that for each surface direction, there are two choices of surface structure, and depending on the chosen structure, the corresponding surface states emerge in distinct regions of the surface Brillouin zone.
Hamdani, A.; 相馬 秀; 安部 諭; 柴本 泰照
Progress in Nuclear Energy, 185, p.105771_1 - 105771_13, 2025/07
被引用回数：0 パーセンタイル：0.00(Nuclear Science & Technology)This study, motivated by previous TEPSYS analysis, examined how different temperatures on the 4th and 5th floors of the Fukushima Daiichi Unit 3 reactor building (R/B) influenced non-condensable gas distribution during the 2011 severe accident. Understanding this is vital for assessing risks related to gas accumulation, especially since the hydrogen explosion may have involved multiple stages. An experimental study was conducted using the CIGMA facility, designed to mimic the R/B structure, where steam and helium (as a substitute for hydrogen) were injected for 10,000 seconds to simulate leakage. Two cooling conditions were tested: 50C (Case 1) and 90C (Case 2). Results showed that the highest concentration of non-condensable gases was often found downstream rather than near the injection point. In Case 1, after 10,000 seconds, helium concentration reached 65% in the middle region (4th floor) and 45% in the top region (5th floor). Analysis indicated that the gas mixture in the middle region posed a potential detonation risk. This study offers crucial insights for enhancing safety measures and risk mitigation strategies in nuclear reactor designs.
佐藤 達彦
Radioisotopes, 74(2), p.183 - 188, 2025/07
モンテカルロ放射線挙動解析コードは、その計算精度が極めて高いため、様々な放射線治療に対する線量評価に活用されている。核医学治療分野においても、SPECT/CTやPET/CT画像をモンテカルロコードの入力ファイルに自動変換して実行し、得られた線量分布を解析するシステムの開発が世界各地で進められている。本稿では、そのシステム開発の現状について紹介するとともに、現在、我々が開発を進めているRT-PHITS (RadioTherapy package based on PHITS)の核医学関連機能について解説する。
Mao, W.*; Gong, W.; 川崎 卓郎; Gao, S.*; 伊東 達矢; 山下 享介*; Harjo, S.; Zhao, L.*; Wang, Q.*
Scripta Materialia, 264, p.116726_1 - 116726_6, 2025/07
被引用回数：0An ultrafine-grained 304 austenitic stainless steel exhibited pronounced serrated Luders deformation at 20 K, with stress and temperature oscillations reaching 200 MPa and 20 K. 
neutron diffraction and digital image correlation revealed discontinuous Luders band propagation and burst martensite formation. During deformation, austenite phase stress remained lower than at upper yielding, indicating elastic behavior. Notably, martensite phase stress stayed lower than austenite until fracture, likely due to stress relaxation from burst martensitic transformation at 20 K. The low martensite stress delayed brittle fracture until austenite plastically yielded during uniform deformation.
Lin, Z. M.*; Liu, B. X.*; Ming, K. S.*; 徐 平光; Yin, F. X.*; Zheng, S. J.*
Scripta Materialia, 263, p.116692_1 - 116692_7, 2025/07
被引用回数：0 パーセンタイル：0.00(Nanoscience & Nanotechnology)Complementary layer thickness effects on strength and plasticity in Q235 and SUS304 steels provide a novel strategy to realize high strength and high plasticity of heterogeneous Q235/SUS304 multilayered steel. In this work, the tensile deformation behaviors and fracture characteristics of vacuum hot-rolled Q235/SUS304 multilayered steel with various layer thicknesses ranging from 223 
m to 5 m were deeply investigated. The tensile strength improved with the reduction of layer thickness, and the uniform elongation were first increasing and then decreasing with the decrease of layer thickness, and the peak value appeared at the layer thickness of 20 m. Interestingly, the fracture elongation forms a high plateau value within the 1020 m range. Further analysis reveals that the severe strain localization in the brittle SUS304 thin layers is delayed by the ductile Q235 layers, which is mainly attributed to the different texture evolution and dislocation configuration characteristics during tensile deformation.
