Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
福田 航大
Annals of Nuclear Energy, 208(1), p.110748_1 - 110748_10, 2024/12
被引用回数：0 パーセンタイル：0.00(Nuclear Science & Technology)The Windscale Works criticality accident in 1970 resulted from mixing an aqueous solution with an organic solvent with different plutonium concentrations and densities. Although this accident has been studied using improved computer capabilities in recent years, a precise criticality scenario has not yet been identified. This study aims to clarify a possible criticality scenario of the accident-the time variation of reactivity and its mechanism. The accident was simulated by combining the multiphase computational fluid dynamics solver of OpenFOAM and the delta-tracking-based Monte Carlo neutron transport code Serpent2. Consequently, the periodic uneven arrangement of fluids might have caused oscillations in neutron leakage and absorption, resulting in periodic wavy reactivity changes. Furthermore, the emulsion, which was thought to be the primary cause, might not be the dominant mechanism for reactivity change, although it contributed to the criticality of the accident.
物質科学研究センター
JAEA-Review 2024-037, 141 Pages, 2024/11
JAEA-Review-2024-037.pdf:13.08MB
JRR-3(Japan Research Reactor No.3)には、日本原子力研究開発機構(原子力機構)が所管する15台の中性子ビーム利用実験装置が設置されており、装置高度化を含めた原子力機構の独自利用を行うとともに施設供用装置として外部利用者に供し、様々な研究成果を創出している。本報告書は、運転再開後の令和3年度、令和4年度の独自利用研究および中性子ビーム利用実験装置の高度化などの技術開発の進捗状況を取りまとめたものである。
小泉 光生; 伊藤 史哲*; Lee, J.; 弘中 浩太; 高橋 時音; 鈴木 敏*; 有川 安信*; 安部 勇輝*; Wei, T.*; 余語 覚文*; et al.
第45回日本核物質管理学会年次大会会議論文集(インターネット), 4 Pages, 2024/11
Neutron resonance transmission analysis (NRTA) is a non-destructive method applicable for measuring nuclear material using a time-of-flight (TOF) technique with a pulsed neutron source. To realize a high resolution compact NRTA system, use of a short-pulsed neutron source is essential. Laser-driven neutron sources (LDNSs) are well-suit for generating such neutron beams due to their short pulse width. The advances in laser technology will further reduce the system's size and improve practicality. In this study, we demonstrate the measurement of a neutron transmission TOF spectrum of a sample containing indium and silver using the LDNS of the Osaka University. The obtained spectrum was analyzed using the least-square nuclear-resonance fitting program, REFIT, showcasing for the first time the potential of an LDNS for nondestructive areal-density material characterization.
-ray fields冠城 雅晃; 鎌田 圭*; 石井 隼也*; 松本 哲郎*; 真鍋 征也*; 増田 明彦*; 原野 英樹*; 加藤 昌弘*; 島添 健次*
Journal of Instrumentation (Internet), 19(11), p.P11019_1 - P11019_17, 2024/11
A new LiCAF:Ce detector with an ultra-thick (99 
m) crystal and optimized readout was developed. The LiCAF:Ce and KG2 detectors were used to detect a sealed Cf-252 neutron source (neutron emission rate of ~
) using a 5 cm thick high-density polyethylene (HDPE) block located at the front of the detector. At the air kerma rates at the front surface of the HDPE block (
) of up to 1.07 Gy/h, the effective neutron count rate (
) for the LiCAF:Ce detector was the same within margins of errors, but it decreased by 5.7 
0.8% at 2.97 Gy/h. In contrast, for the KG2 detector, with increased up to 1.07 Gy/h, for KG2 increased up to 20 1.0 % at 1.07 Gy/h. Then, decreased by 20 1.0% at 2.97 Gy/h. Therefore, the LiCAF:Ce detector exhibited a smaller influence on neutron count rates by -rays compared to the KG2 detector because of the faster decay time and optimization of digital pulse processing.
neutron diffraction study to elucidate hydrogen effect on the deformation mechanism in Type 310S austenitic stainless steel伊東 達矢; 小川 祐平*; Gong, W.; Mao, W.*; 川崎 卓郎; 岡田 和歩*; 柴田 曉伸*; Harjo, S.
Proceedings of the 7th International Symposium on Steel Science (ISSS 2024), p.237 - 240, 2024/11
Hydrogen embrittlement has long been an obstacle to the development of safe infrastructure. However, in contrast to hydrogen's embrittling effect, recent research has revealed that the addition of hydrogen improves both the strength and uniform elongation of AISI Type 310S austenitic stainless steel. A detailed understanding of how hydrogen affects the deformation mechanism of this steel could pave the way for the development of more advanced materials with superior properties. In the present study, 
neutron diffraction experiments were conducted on Type 310S steel with and without hydrogen-charged to investigate the effect of hydrogen on the deformation mechanism. In addition to the effect of solid-solution strengthening by hydrogen, the q-value, a parameter representing the proportion of edge and screw dislocations in the accumulated dislocations, was quantitatively evaluated using CMWP analysis on neutron diffraction patterns. The comparison of q-values between the hydrogen-charged and non-charged samples reveals that hydrogen has minimal effect on dislocation character in Type 310S steel.
横山 賢治; 羽様 平; 谷中 裕; 大木 繁夫
JAEA-Data/Code 2024-007, 41 Pages, 2024/10
JAEA-Data-Code-2024-007.pdf:1.1MB
汎用炉心解析システムMARBLEの第3版であるMARBLE3を開発した。MARBLEの開発ではオブジェクト指向スクリプト言語Pythonを用いており、これまでの開発ではPythonバージョン2(Python2)を用いていたが、Pythonのバージョンアップの後方非互換性の問題により、Pythonの最新版であるPythonバージョン3(Python3)では、MARBLEを動作させることができなくなっていた。このため、MARBLE3の開発では全面的に改修を行って、Python3で動作するように整備した。また、MARBLE3では、新しく開発された解析コードのカプセル化や新しく提案された計算手法等の組み込みを行うとともに、メンテナンス性や拡張性、柔軟性の観点からユーザインターフェースの拡張やソルバーの再実装等を行った。MARBLE3では、新規に開発された3次元六角/三角体系輸送計算コードMINISTRIVer.7(MINISTRI7)と3次元六角/三角体系拡散計算コードD-MINISTRIを利用できるように整備した。これらのコードは、MARBLEのサブシステムである核特性解析システムSCHEMEや高速炉燃焼解析システムOPRHEUSで利用できる。また、MARBLEに組み込まれている炉心解析システムCBGのユーザインターフェースを拡張して、CBGの2次元RZ体系の拡散計算ソルバーや輸送計算ソルバーをSCHEME上で利用できるように整備した。一方、計算手法についても改良を加えた。MARBLE3では、チェビシェフ有理関数近似法に基づく燃焼計算手法の改良に関する論文やミニマックス多項式近似法に基づく燃焼計算手法に関する論文で提案された計算手法を利用できるように、燃焼計算ソルバーの機能拡張を行った。また、メンテナンス性の観点から、MARBLE2で導入された一点炉動特性ソルバーPOINTKINETICSを廃止して、MARBLE3ではKINETICSソルバーとして新たに整備し直した。
Mao, W.*; Gao, S.*; Gong, W.; 川崎 卓郎; 伊東 達矢; Harjo, S.; 辻 伸泰*
Acta Materialia, 278, p.120233_1 - 120233_13, 2024/10
被引用回数：1 パーセンタイル：71.29(Materials Science, Multidisciplinary)Using a hybrid method of in situ neutron diffraction and digital image correlation, we found that ultrafine-grained 304 stainless steel exhibits Luders deformation after yielding, in which the deformation behavior changes from a cooperation mechanism involving dislocation slip and martensitic transformation to one primarily governed by martensitic transformation, as the temperature decreases from 295 K to 77 K. Such martensitic transformation-governed Luders deformation delays the activation of plastic deformation in both the austenite parent and martensite product, resulting in delayed strain hardening. This preserves the strain-hardening capability for the later stage of deformation, thereby maintaining a remarkable elongation of 29% while achieving a high tensile strength of 1.87 GPa at 77 K.
石川 諒尚; 田中 浩基*; 中村 哲志*; 熊田 博明*; 櫻井 良憲*; 渡辺 賢一*; 吉橋 幸子*; 棚上 裕生*; 瓜谷 章*; 鬼柳 善明*
Journal of Radiation Research (Internet), 11 Pages, 2024/10
被引用回数：0From the viewpoints of the advantage depths (ADs), peak tumor dose, and skin dose, we evaluated the effect of neutron beam properties, namely, the ratio between thermal and epithermal neutron fluxes (thermal/epithermal ratio), fast neutron component, and -ray component on the dose distribution. Several parameter surveys were conducted with respect to the beam properties of neutron sources for boron neutron capture therapy assuming boronophenylalanine as the boron agent using our dose calculation tool, called SiDE. The ADs decreased by 3% at a thermal/epithermal ratio of 20% - 30% compared with the current recommendation of 
. The skin dose increased with the increasing thermal/epithermal ratio, reaching a restricted value of 14 Gy-eq at a thermal/epithermal ratio of 
. The fast neutron component was modified using two different models, namely, the "linear model," in which the fast neutron intensity decreases log-linearly with the increasing neutron energy, and the "moderator thickness (MT) model," in which the fast neutron component is varied by adjusting the moderator thickness in a virtual beam shaping assembly. Although a higher fast neutron component indicated a higher skin dose, the increment was 
at a fast neutron component of 
Gy cm
for both models. Furthermore, in the MT model, the epithermal neutron intensity was 
higher at a fast neutron component of 
Gy cm compared with the current recommendation of 
Gy cm. The -ray component also caused no significant disadvantages up to several times larger compared with the current recommendation.
Zhang, Y.-J.*; 梅田 岳昌*; 諸岡 聡; Harjo, S.; 宮本 吾郎*; 古原 忠*
Metallurgical and Materials Transactions A, 55(10), p.3921 - 3936, 2024/10
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)In this study, a series of eutectoid steels with Mn addition up to 2 mass% were isothermally transformed at various temperatures from 873 K to 973 K to clarify the pearlite growth kinetics and the underlying thermodynamics at its growth front. The microscopic observation indicates the acceleration in pearlite growth rate and refinement in lamellar spacing by decreasing the transformation temperature or the amount of Mn addition. After analyzing the solute distribution at pearlite growth front via three-dimensional atom probe, no macroscopic Mn partitioning across pearlite/austenite interface is detected, whereas Mn segregation is only observed at ferrite/austenite interface. Furthermore, in-situ neutron diffraction measurements performed at elevated temperatures reveals that the magnitude of elastic strain generated during pearlite transformation is very small.
廃炉環境国際共同研究センター; 海上・港湾・航空技術研究所*
JAEA-Review 2024-020, 77 Pages, 2024/09
JAEA-Review-2024-020.pdf:3.34MB
日本原子力研究開発機構(JAEA)廃炉環境国際共同研究センター(CLADS)では、令和4年度英知を結集した原子力科学技術・人材育成推進事業(以下、「本事業」という)を実施している。本事業は、東京電力ホールディングス株式会社福島第一原子力発電所の廃炉等をはじめとした原子力分野の課題解決に貢献するため、国内外の英知を結集し、様々な分野の知見や経験を、従前の機関や分野の壁を越えて緊密に融合・連携させた基礎的・基盤的研究及び人材育成を推進することを目的としている。平成30年度の新規採択課題から実施主体を文部科学省からJAEAに移行することで、JAEAとアカデミアとの連携を強化し、廃炉に資する中長期的な研究開発・人材育成をより安定的かつ継続的に実施する体制を構築した。本研究は、令和2年度に採択された研究課題のうち、「無人航走体を用いた燃料デブリサンプルリターン技術の研究開発」の令和2年度から令和4年度分の研究成果について取りまとめたものである。本研究は、日英共同研究体制の下、耐放射線性を持ちつつ中性子検出効率を向上させた中性子検出器と、強力な切削能と収集能を持ったエンドエフェクタ並びにマニピュレータを融合させた燃料デブリサンプリング装置を開発し、それらを無人航走体へ搭載させた燃料デブリサンプリングシステムを構築することを目指したものである。さらに、システム位置を同定する測位システムと、光学カメラ、ソナー、今回開発する中性子検出器の計数情報を仮想現実システムへ投影させる技術を開発し、遠隔操作技術の向上に貢献する技術開発を行った。日本側が担当した燃料デブリマッピングツールの開発では、1)高耐放射線小型高効率中性子センサの開発、2)UUVプラットホームの開発、3)放射線環境シミュレーション及び積算中性子線量計の特性評価を実施した。実施項目1)ではシリコン半導体検出器に微細構造を施して中性子の感度を上げ、ガンマ線の感度を下げたMSNDの特性評価と専用集積回路を開発し、小型高効率中性子センサを実現した。実施項目2)では、燃料デブリマッピングツール構成要素(中性子センサ、水中カメラ、ソナー、LiDAR)が連動するための通信制御系とUUVプラットホームとのインターフェースを完成させた。
Zhu, L.*; He, H.*; Naeem, M.*; Sun, X.*; Qi, J.*; Liu, P.*; Harjo, S.; 中島 健次; Li, B.*; Wang, X.-L.*
Physical Review Letters, 133(12), p.126701_1 - 126701_6, 2024/09
It has long been suspected that magnetism could play a vital role in the phase stability of multi- component high-entropy alloys. However, the nature of the magnetic order, if any, has remained elusive. Here, by using elastic and inelastic neutron scattering, we demonstrate evidence of antiferromagnetic order below 
80 K and strong spin fluctuations persisting to room temperature in a single-phase face-centered cubic (fcc) CrMnFeCoNi high-entropy alloy. Despite the chemical complexity, the magnetic structure in CrMnFeCoNi can be described as -Mn-like, with the magnetic moments confined in alternating (001) planes and pointing toward the 
111
direction. Combined with first-principles calculation results, it is shown that the antiferromagnetic order and spin fluctuations help stabilized the fcc phase in CrMnFeCoNi high-entropy alloy.
小泉 光生; 伊藤 史哲*; Lee, J.; 弘中 浩太; 高橋 時音; 鈴木 敏*; 有川 安信*; 安部 勇輝*; Lan, Z.*; Wei, T.*; et al.
Scientific Reports (Internet), 14, p.21916_1 - 21916_9, 2024/09
被引用回数：0Laser-driven neutron sources (LDNSs) can generate strong short-pulse neutron beams, which are valuable for scientific studies and engineering applications. Neutron resonance transmission analysis (NRTA) is a nondestructive technique used for determining the areal density of each nuclide in a material sample using pulsed thermal and epithermal neutrons. Herein, we report the first successful NRTA performed using an LDNS driven by the Laser for Fast Ignition Experiment at the Institute of Laser Engineering, Osaka University. The key challenge was achieving a well-resolved resonance transmission spectrum for material analysis using an LDNS with a limited number of laser shots in the presence of strong background noise. We addressed this by employing a time-gated 
Li-glass scintillation neutron detector to measure the transmission spectra, reducing the impact of electromagnetic noise and neutron and gamma-ray flashes. Output waveforms were recorded for each laser shot and analyzed offline using a counting method. This approach yielded a spectrum with distinct resonances, which were attributed to 
In and 
Ag, as confirmed through neutron transmission simulation. The spectrum was analyzed using the least-square nuclear-resonance fitting program, REFIT, demonstrating the possibility of using an LDNS for nondestructive areal-density material characterization.
Ying, H.*; Yang, X.*; He, H.*; Yan, A.*; An, K.*; Ke, Y.*; Wu, Z.*; Tang, S.*; Zhang, Z.*; Dong, H.*; et al.
Scripta Materialia, 250, p.116181_1 - 116181_7, 2024/09
被引用回数：1 パーセンタイル：71.29(Nanoscience & Nanotechnology)Nanoscale chemical fluctuations and their effect on the deformation behavior of CrFeCoNi-based high-entropy alloys (HEAs) were investigated using small-angle scattering and in situ neutron diffraction measurements. Small-angle scattering results demonstrated the presence of nano (
10 nm) chemical fluctuations in the as-prepared CrFeCoNiPd HEAs, which was attributed to the negative mixing of enthalpy and the significant atomic radius difference between Pd and the constituent elements in the CrFeCoNi-based alloys. Subsequent tensile tests demonstrated that the yield and tensile strengths of the as-prepared CrFeCoNiPd HEA surpass those of the as-prepared CrMnFeCoNi HEA. Neutron diffraction data analysis revealed an anomalous response of dislocation evolution with the strain.
長谷美 宏幸; 甲斐 哲也
JAEA-Testing 2024-001, 39 Pages, 2024/08
JAEA-Testing-2024-001.pdf:1.4MB
RAIM (Resonance Analysis code for neutron IMaging)は大強度陽子加速器施設J-PARCの物質・生命科学実験施設(MLF)などのパルス中性子源で測定した共鳴吸収スペクトルを解析し、試料の原子核の密度や温度などの情報を求める解析コードである。RAIMは中性子のパルス関数と断面積データをもとにした共鳴吸収関数の畳み込み計算によりパルス中性子源で測定される共鳴吸収スペクトルを再現し、測定で得られた共鳴吸収スペクトルデータに対してフィッティングを行うことで、試料に含まれる特定の元素の密度や温度を求めることができる。また、RAIMは計算設定のパラメータを極力少なくすることや、2次元検出器で測定した数多くのスペクトルを一括で処理するスクリプトを用意するなど、共鳴イメージングデータを容易に解析することを念頭に開発されている。本書はRAIMの計算機へのインストール方法および共鳴吸収スペクトルのシミュレーションと測定データへのフィッティング方法について説明するマニュアルである。
遠藤 駿典; 安部 亮太*; 藤岡 宏之*; 猪野 隆*; 岩本 修; 岩本 信之; 河村 しほり*; 木村 敦; 北口 雅暁*; 小林 龍珠*; et al.
European Physical Journal A, 60(8), p.166_1 - 166_10, 2024/08
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)Measurements of -ray circular polarization emitted from neutron capture reactions provide valuable information for nuclear physics studies. The spin and parity of excited states can be determined by measuring the circular polarization from polarized neutron capture reactions. Furthermore, the -ray circular polarization in a neutron capture resonance is crucial for studying the enhancement effect of parity nonconservation in compound nuclei. The -ray circular polarization can be measured using a polarimeter based on magnetic Compton scattering. A polarimeter was constructed, and its performance indicators were evaluated using a circularly polarized -ray beam. Furthermore, as a demonstration, the -ray circular polarization was measured in 
S(n,)
S reactions with polarized neutrons.
遠藤 章
Radiation Protection Dosimetry, 200(13), p.1266 - 1273, 2024/08
被引用回数：0 パーセンタイル：0.00(Environmental Sciences)本研究では、外部中性子照射における周辺線量
、周辺線量当量
及び実効線量の関係を、様々な作業場の163種類の中性子スペクトルを用いて分析した。その結果、実効線量の評価に対して、は中性子のエネルギー分布によっては著しく過大あるいは過小評価する一方、は過大評価の場合でも適度な範囲内で合理的な推定値を与えることが明らかになった。本研究は、特に高エネルギー中性子が存在する環境における線量評価に対して、実用量の要件から見たの限界との優位性を示した。
Cf rotation method with a water Cherenkov neutron detector田辺 鴻典*; 米田 政夫; 藤 暢輔; 北村 康則*; 三澤 毅*; 土屋 兼一*; 相楽 洋*
Scientific Reports (Internet), 14, p.18828_1 - 18828_10, 2024/08
被引用回数：0The global challenge of on-site detection of highly enriched uranium (HEU), a substance with considerable potential for unauthorized use in nuclear security, is a critical concern. Traditional passive nondestructive assay (NDA) techniques, such as gamma-ray spectroscopy with high-purity germanium detectors, face significant challenges in detecting HEU when it is shielded by heavy metals. Addressing this critical security need, we introduce an on-site detection method for lead-shielded HEU employing a transportable NDA system that utilizes the Cf rotation method with a water Cherenkov neutron detector. This cost-effective NDA system is capable of detecting 4.17 g of 
U within a 12 min measurement period using a Cf source of 3.7 MBq. Integrating this system into border control measures can enhance the prevention of HEU proliferation significantly and offer robust deterrence against nuclear terrorism.
渡邊 未来*; 宮本 吾郎*; Zhang, Y.*; 諸岡 聡; Harjo, S.; 小林 康浩*; 古原 忠*
ISIJ International, 64(9), p.1464 - 1476, 2024/07
The mechanical properties of TRIP steels depend on heterogeneities of chemical composition and grain size in the retained structure, although these heterogeneities have not been characterized in detail. Therefore, in this study, we quantitatively investigate the inhomogeneous carbon concentration and grain size distribution, and its effects on the thermal stability of the retained in Fe-2Mn-1.5Si-0.4C (mass%) TRIP steel using FE-EPMA, EBSD, M
ssbauer spectroscopy, and in-situ neutron diffraction during bainitic transformation at 673 K. In-situ neutron diffraction experiments detects high-carbon evolving during bainite transformation, in addition to the original , and the time variation of the volume fraction of highcarbon agrees well with the fraction of retained at room temperature. Williamson-Hall analysis based on peak width suggests that heterogeneity of carbon content exists even within the high-carbon . Compositional analysis using FE-EPMA and three-dimensional atom probe directly revealed that fine filmy was highly enriched with carbon compared to larger blocky , and the carbon content in blocky decreases with increasing blocky size. DICTRA simulation qualitatively reproduces the size dependency of carbon enrichment into . It was also found that tends to be retained at higher carbon content and smaller grain size since the smaller grain size directly improves thermal stability and the smaller size further contributes to the thermal stability via enhanced carbon enrichment.
松下 慧*; 土田 紀之*; 石丸 詠一郎*; 平川 直樹*; Gong, W.; Harjo, S.
Journal of Materials Engineering and Performance, 33(13), p.6352 - 6361, 2024/07
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)This study investigated the anisotropy of the tensile properties in a duplex stainless steel of 24Cr-5Ni-0.18N based on in situ neutron diffraction experiments. The 24Cr-5Ni-0.18N steel showed a better balance of tensile strength (TS) and uniform elongation (U.El) compared with 329J4L and 329J1 steels. The Lankford value (
-value) of the 24Cr-5Ni-0.18N steel was comparable to other duplex stainless steels while showing a larger TS. Regarding the anisotropy of the mechanical properties, the results for a test specimen oriented at 45
showed a low yield strength (YS) and TS, but a better U.El and -value. The neutron diffraction results are discussed to explain the mechanical properties.
Nguyen, T.-D.*; Singh, C.*; Kim, Y. S.*; Han, J. H. *; Lee, D.-H.*; Lee, K.*; Harjo, S.; Lee, S. Y.*
Journal of Materials Research and Technology, 31, p.1547 - 1556, 2024/07
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)This study investigates the mechanical properties of a friction-stir-welded (FSW) AA6061-T6 aluminum alloy at ultra-low temperature (ULT) of 20 K. In-situ neutron diffraction and orientation imaging microscopy were employed to compare the tensile deformation behavior of the base metal (BM) and heat-affected zone (HAZ) in the FSW aluminum plate. The results demonstrate that compared to room-temperature (RT), ULT induces a significant improvement in tensile strength and ductility in both the BM and HAZ. The enhanced mechanical properties in BM at ULT result from a more homogeneous deformation than occurs at RT. On the other hand, HAZ at ULT exhibits an even lower yield strength than at RT, but the strain hardening rate (SHR) is the most significant among the alloys, leading to a tensile strength of 346 MPa and the highest ductility of 46.8%. The lowest yield strength corresponds to the lowest-hardness zones in HAZ, caused by dissolved/coarsened precipitates during the FSW process.
