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論文

Investigating eutectic behavior and material relocation in B $_{4}$ C-stainless steel composites using the improved MPS method

Ahmed, 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

https://doi.org/10.1016/j.ijheatmasstransfer.2025.127343

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.

論文

Densities, surface tensions, and viscosities of molten high-silicon electrical steels with different silicon contents

Neubert, L.*; Bell, M. R.*; 山本泰生*; 西剛史*; 山野秀将; Ahrenhold, F.*; Volkova, O.*

Steel Research International, 96(5), p.202400237_1 - 202400237_8, 2025/05

https://doi.org/10.1002/srin.202400237

被引用回数：2 パーセンタイル：0.00(Metallurgy & Metallurgical Engineering)

Density, surface tension, and viscosity of various liquid electrical steels are measured at different temperatures, varying in their silicon content between 3 and 6mass%.

論文

Density, surface tension, and viscosity of molten Ni-based superalloys using the maximum bubble pressure and oscillating crucible methods

西剛史*; 松本早織*; 山野秀将; 林喜一郎*; 遠藤理恵*; Bell, M. R.*; Neubert, L.*; Volkova, O.*

Steel Research International, 96(5), p.2300766_1 - 2300766_6, 2025/05

https://doi.org/10.1002/srin.202300766

被引用回数：4 パーセンタイル：75.40(Metallurgy & Metallurgical Engineering)

ニッケル基超合金について、密度は最大気泡圧法、粘度はるつぼ振動法、表面張力は最大気泡圧法により、測定データを得た。

論文

Density of a molten stainless steel-B $_{4}$ C alloy measured in the electrostatic levitation furnace onboard the international space station

石川毅彦*; 織田裕久*; 小山千尋*; 下西里奈*; 池内留美子*; Paradis, P.-F.*; 岡田純平*; 福山博之*; 山野秀将

International Journal of Microgravity Science and Application, 42(2), p.420202_1 - 420202_10, 2025/04

https://doi.org/10.15011/jasma.42.420202

Samples of stainless steel (SS) - boron carbide (B $_{4}$ C) alloys were levitated in the Electrostatic Levitation Furnace onboard the International Space Station (ISS-ELF) to measure the thermophysical properties of their melts. Melting of samples of two different compositions (SS-12.3, and 28 mass% B $_{4}$ C) were attempted in the furnace. Even though only one sample (SS-12.3 mass% B $_{4}$ C) could be melted, its density was successfully obtained.

論文

Radiation heating effects on B $_{4}$ C-SS eutectic melting and its relocation behaviour

Ahmed, Z.*; Sharma, A. K.*; Pellegrini, M.*; 山野秀将; 岡本孝司*

Arabian Journal for Science and Engineering, 50(5), p.3361 - 3371, 2025/03

https://doi.org/10.1007/s13369-024-09412-9

被引用回数：0 パーセンタイル：0.00(Multidisciplinary Sciences)

This study pioneers the use of radiative heating for high-resolution visualisation and quantification of the eutectic melt composition, providing a novel approach to observing the melting and candling phenomena. Key findings include two distinct failure processes: SS cladding detachment forming molten droplets and fragmentation of B $_{4}$ pellets, with sintering observed in B $_{4}$ powder.

論文

「地球環境に対する人類活動の影響」、「地球温暖化と造礁サンゴの北上」

三ツ口丈裕; 山野博哉*

全地球史; 世界で集めた地球史のかけら, p.59 - 60, 2025/03

18世紀の産業革命以降、人類活動が地球環境に及ぼす影響が顕著化したのは1950年代以降であり、例えば、(1)化石燃料の大量消費に伴う二酸化炭素・熱の大量排出、(2)工業化に伴う人工化学物質の放出、(3)核エネルギー開発(大気圏核実験や核燃料再処理)に伴う特定の放射性核種(ヨウ素129や炭素14)の放出である。また、近年の地球温暖化により日本列島周辺域の海水温が上昇し続けており、これに伴って、従来は温暖な南方海域にのみ生息していた造礁サンゴ種が黒潮にのって北上している。

論文

Density, surface tension, and viscosity of liquid low-sulfur manganese-boron steel via maximum bubble pressure and oscillating crucible methods

Bell, M. R.*; Neubert, L.*; Sherstneva, A.*; 山本泰生*; 西剛史*; 山野秀将; Weinberg, M.*; Volkova, O.*

Steel Research International, p.2400252_1 - 2400252_10, 2025/00

https://doi.org/10.1002/srin.202400252

被引用回数：1 パーセンタイル：0.00(Metallurgy & Metallurgical Engineering)

低硫黄マンガンボロン鋼について、異なる温度域でボロンと硫黄の含有量を変えて、物性値を測定した。

論文

次世代革新炉(高速炉と高温ガス炉)開発の最前線,1; 次世代革新炉開発の国内外動向

山野秀将; 豊岡淳一; 佐藤博之; 坂場成昭

日本原子力学会誌ATOMO, 66(12), p.607 - 611, 2024/12

https://doi.org/10.3327/jaesjb.66.12_607

主要な開発国を対象に国外の高速炉開発動向を紹介するとともに、国内動向を紹介する。

論文

First freezing experiments with a molten mixture of boron carbide and stainless steel in core disruptive accidents of sodium-cooled fast reactors

江村優軌; 松場賢一; 菊地晋; 山野秀将

Proceedings of 13th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS13) (Internet), 8 Pages, 2024/11

Assuming the CDA of SFRs, the eutectic melting between B $_{4}$ C as a control rod material and stainless steel (SS) as a structural material could occur below their melting points. After that, the mixture produced by eutectic melting between B $_{4}$ C and SS (B $_{4}$ C-SS mixture) would relocate inside or outside of the original core region. From the viewpoint of core reactivity changes, the relocation behavior of B $_{4}$ C-SS mixture induced by its melting/freezing behavior, is one of the key elements to evaluate the CDA consequences. Many experimental studies on freezing behavior using core materials and its simulants, including molten UO $_{2}$ , SS, tin, wood's metal have been reported in the past. Based on these experimental findings, the freezing/blockage model for the severe accident simulation code was established and discussed through analyses of freezing process. Specifically, it has been considered that the experimental correlation of melt-penetration length was a key indicator to quantitatively describe freezing behavior. However, there was no experimental data for the freezing behavior of actual B $_{4}$ C-SS mixture. Therefore, the freezing experiments of B $_{4}$ C-SS mixture were conducted to investigate the freezing and blockage behavior inside a flow path such as fuel pin bundle. In the freezing experiments, B $_{4}$ C powder and SS block were heated up to around 1,750 K using a graphite heating furnace, then B $_{4}$ C-SS mixture flowed down into an SS pipe for cooling below 750 K. The experimental results showed that the B $_{4}$ C-SS mixture solidified and resulted in the blockage in the SS pipe with 4 mm or 6.7 mm in inner diameter, respectively. Furthermore, the observations for cross section of SS pipe suggested that the B $_{4}$ C-SS mixture penetrated deeper than molten SS. This difference is considered to be influenced by decrease of the melting point.

論文

A Preliminary study for boron mixing effect on severe accident scenario in sodium-cooled fast reactor

山野秀将; 守田幸路*

Proceedings of 13th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS13) (Internet), 9 Pages, 2024/11

This study is intended to investigate the effect of boron mixing in the degraded core using the eutectic reaction model between B $_{4}$ C and SS. Two difference B $_{4}$ C particle sizes were used to examine the effect of the boron dilution in the degraded core material mixture. The tight fluid-particle momentum coupling in the case of small size of B $_{4}$ C particles allows boron to keep remaining in the core mixture in a longer time than in the case of nominal size of B $_{4}$ C particles. However, this preliminary calculation showed that the upward motion of the eutectic melt in the molten core pool as well as the reactivity transient behavior caused by the molten core material relocation. This analysis indicated that the reactivity increase could be delayed thanks to the boron mixing.

報告書

SIMMER-III and SIMMER-IV; Computer codes for LMFR core disruptive accident analysis

近藤悟; 飛田吉春*; 守田幸路*; 神山健司; 山野秀将; 鈴木徹*; 田上浩孝; 曽我部丞司; 石田真也

JAEA-Research 2024-008, 235 Pages, 2024/10

JAEA-Research-2024-008.pdf:4.77MB

日本原子力研究開発機構が開発したSIMMER-III及びSIMMER-IVは、2次元/3次元、多速度場、多成分流体力学モデルを空間・時間依存の核動特性モデルと結合した計算コードであり、液体金属高速炉の炉心崩壊事故の解析に広く利用されている。従来コードに対して次のような高度化したモデルが採用されている。すなわち、安定かつ頑健な流体力学アルゴリズム、最大8までの多速度場モデル、構造材及び多相流幾何形状の取扱いの改善、熱及び質量移行過程の包括的取扱い、高精度の状態方程式、高精度かつ高効率の中性子束計算モデル、崩壊熱モデルなどである。本報告書ではSIMMER-III及びSIMMER-IVのモデル及び解法の詳細を記述する。別途詳細が報告されている個別モデルについてはその概要をまとめる。なお、コードの検証及び妥当性確認についてはすでに報告済みである。

論文

Development of failure mitigation technologies for improving resilience of nuclear structures

笠原直人*; 山野秀将; 中村いずみ*; 出町和之*; 佐藤拓哉*; 一宮正和*

International Journal of Pressure Vessels and Piping, 211, p.105298_1 - 105298_6, 2024/10

https://doi.org/10.1016/j.ijpvp.2024.105298

Passive safety structures were applied to next-generation fast reactors, subject to high temperature and low-pressure conditions. In the case of loss-of-heat-removal accidents, high temperature conditions accelerate the creep deformation of structures. When deformation redistributes loadings and reduces stresses at important positions such as coolant boundaries, progression to creep rupture of boundaries can be mitigated. When an excessive earthquake occurs, plastic deformation and buckling become dominant, due to low pressure and, therefore, a thin-wall structure. The above-mentioned failure modes reduce rigidity and natural frequency. When the natural frequency becomes lower than the input frequency, vibration energy is hardly transferred to structures and the subsequent failures of structures, such as collapse and break, are mitigated.

論文