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出井 俊太郎; 柴田 真仁*; 根岸 久美*; 杉浦 佑樹; 天野 由記; Bateman, K.*; Wilson, J.*; 横山 立憲; 鏡味 沙耶; 武田 匡樹; et al.
Results in Earth Sciences (Internet), 3, p.100097_1 - 100097_16, 2025/12
高レベル放射性廃棄物の地層処分において、セメントと泥岩の相互作用による化学的擾乱領域が形成され、岩盤中の核種移行特性に影響を及ぼす可能性がある。本研究では、11年前に幌延深地層研究センターの140m調査坑道に施工されたセメント(普通ポルトランドセメント(OPC)および低アルカリ性セメント(LAC))と泥岩の界面における変質状態について調査した。複数の分析手法を組み合わせることで、セメントの溶解、方解石やC-(A-)S-H相などの二次鉱物の析出、モンモリロナイトの陽イオン交換、泥岩の空隙率の低下など、セメントと岩石の界面における主要な反応が特定された。また、空隙率の低下による拡散の低下や、変質した泥岩中の二次鉱物への取り込みによる収着の促進など、セメントと泥岩の相互作用が放射性核種の移行に及ぼす影響についても明らかになった。
大塚 直彦*; Devi, V.*; 岩本 修
Applied Radiation and Isotopes, 225, p.111903_1 - 111903_18, 2025/11
被引用回数：0We developed a set of EXFOR utility codes (ForEXy) to process the information of the experimental nuclear reaction data stored in the EXFOR library. We designed a new JSON format (J4) for the EXFOR library, and developed a code converting the information in an EXFOR file to a J4 file (X4TOJ4) and another code converting it to an EXFOR file (J4TOX4) as a core part of this new code package. We also developed some other codes for management of the EXFOR storage, bibliography and dictionary. As an application of the new code package, we constructed covariance matrices for the fast neutron induced fission cross sections of neptunium-237 in the EXFOR library by using the new codes, and applied them to evaluation of the cross section between 100 keV and 200 MeV.
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
被引用回数：0The 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.
久保 光太郎; 森 憲治*; 村松 健
Nuclear Engineering and Design, 442, p.114176_1 - 114176_14, 2025/10
被引用回数：0Nuclear fuel cycle facilities are important elements for supporting the efficient use of energy resources by establishing a nuclear fuel cycle. However, given that the risks of these facilities are lower than those of nuclear power plants, it is considered reasonable to apply simplified assessment methods when evaluating seismic risks. In this study, a simplified quantification method is proposed for seismic risk assessment at such facilities. Traditional simplified methods have streamlined the assessment process by selecting only representative components, often neglecting others. In contrast, the proposed method simplifies the required computational processes while considering all components by applying Clark approximation. Clark approximation is a mathematical method for approximating the maximum of two normal distributions as a new normal distribution. The proposed method was validated by comparing its seismic probabilistic risk assessment with those performed using Monte Carlo simulations and traditional simplified methods. Results showed that although the proposed method overestimated the high confidence of low probability of failure by a relative difference of 0.15 compared with that of the Monte Carlo method under completely independent condition, the overall plant-level fragility curve was generally within the range of the 5% and 95% confidence fragility curves. The proposed method accounted for the impact of correlated failure, which is critical in seismic risk assessments. Thus, this method enabled the seismic risk assessment of nuclear fuel cycle facilities in a simplified manner without compromising accuracy, potentially contributing to examining risk mitigation measures and developing risk-informed safety regulations for these facilities.
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 パーセンタイル：0.00(Nuclear Science & Technology)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。
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：0 パーセンタイル：0.00(Chemistry, Physical)Metakaolin-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 study will enhance the knowledge on MKGP for pollutant immobilization, thereby mitigating the spread of contaminants in the environment and expanding the potential application areas.
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：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)FeN 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.
neutron diffraction study山下 享介*; 古賀 紀光*; Mao, W.*; Gong, W.; 川崎 卓郎; Harjo, S.; 藤井 英俊*; 梅澤 修*
Materials Science and Engineering A, 941, p.148602_1 - 148602_11, 2025/09
被引用回数：0Ferrite-austenite duplex stainless steels offer excellent strength and ductility, making them suitable for extreme environments. In this study, 
neutron diffraction during tensile testing at 293 K and 200 K was used to investigate stress partitioning and phase-specific deformation. Phase stress was calculated using a texture-compensated method. At both temperatures, ferrite showed higher phase stress than austenite, acting as the harder phase. At 200 K, both phases exhibited increased strength and work hardening. Austenite showed significant stacking fault formation alongside dislocation migration, while ferrite retained its dislocation-based deformation mode, becoming more effective. Stress contributions from both phases were comparable. No martensitic transformation occurred. Strengthening and enhanced work hardening in both phases led to high strength at 200 K, with ductility similar to that at 293 K.
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.
田村 由起子*; 荒川 勝利*; 竹中 幹人*; 中西 洋平*; 藤波 想*; 柴田 基樹*; 山本 勝宏*; 宮田 登*; 山田 雅子*; 瀬戸 秀紀*; et al.
Polymer, 333, p.128662_1 - 128662_8, 2025/08
被引用回数：0To investigate the relationship between the mechanical properties of silica-filled styrene-butadiene rubber (SBR) and the amount of bound rubber at the filler/rubber interface, the polymer matrix was extracted from silica-filled SBR using toluene at room temperature. In this study, this extraction process was reproduced by leaching a thermally annealed SBR layer deposited on a Si substrate in toluene at room temperature, where the adsorption layer of the SBR was grown at the interface with the substrate by thermal annealing. The SBR adsorption layer on the Si substrate has two-layer structures consisting of an inner and outer adsorption layers, which correspond to the tightly and loosely bound rubbers on the filler surface of the silica-filled SBR, respectively. For the sample annealed for less than 6 h, the outer adsorption layer, loosely bound to the substrate, was easily leached in toluene for 5 min, leaving only the inner adsorption layer on the substrate. For the samples annealed for more than 24 h, a large portion of the outer adsorption layer remained on top of the inner adsorption layer as a terrace structure. However, even for the sample annealed for 24 h, treating with toluene for 24 h completely leached the outer adsorption layer from the inner adsorption layer, although the inner adsorption layer remained on the substrate. It was found that the loosely bound rubber in the silica-filled SBR could be easily extracted from the filler surface, along with the free polymer chains in the polymer matrix during extraction with toluene at room temperature. In contrast, the tightly bound rubber was not leached by toluene at room temperature. This may be because the interfacial polymer chains within approximately 1 nm of the substrate surface were strongly constrained to the substrate, and even toluene molecules were excluded.
(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：0 パーセンタイル：0.00(Nanoscience & Nanotechnology)The 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.
青野 竜士; 後藤 勝則*; 木名瀬 暁理; 佐藤 義行; 原賀 智子; 伊勢田 浩克
JAEA-Data/Code 2025-006, 24 Pages, 2025/07
JAEA-Data-Code-2025-006.pdf:1.05MB
日本原子力研究開発機構の研究施設等から発生する放射性廃棄物は、放射能レベルに応じて将来的にトレンチとピットに分けて浅地中処分される予定であり、埋設処分を開始するまでに、廃棄体の放射能濃度を評価する方法を構築する必要がある。そこで、原子力科学研究所バックエンド技術部では、研究施設等廃棄物に対する放射能濃度評価方法の検討に資するため、保管廃棄施設・Lに保管されている圧縮体より分析試料を採取し、放射化学分析を実施した。本報告書は、令和2年度に取得した12核種(
H、
C、
Co、
Sr、
Nb、
Cs、
Eu、
Eu、
Pu、
Pu、
Pu、
Am)の放射能濃度データについて整理し、放射能濃度評価方法の検討のための基礎資料としてまとめたものである。
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。
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：1 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。
村上 昌史; 吉田 幸彦; 南郷 脩史*; 久保田 省吾*; 黒澤 卓也*; 佐々木 紀樹
Journal of Nuclear Science and Technology, 62(7), p.650 - 661, 2025/07
被引用回数：0 パーセンタイル：0.00(Nuclear Science & Technology)Nondestructive methods were investigated to effectively discriminate disposal-restricted materials, including aluminum, batteries, combustibles, lead, and mercury, inside waste containers without opening them. An industrial computed tomography (CT) system with maximum X-ray energy of 9 MeV was used to visualize inside 27-cm diameter pails and 59-cm diameter drums filled with typical waste materials such as combustibles, glass, concrete, and metals. The CT images with 0.5 mm spacing were acquired, and three-dimensional (3D) models were constructed. A good linear relationship was observed between the gray values in the obtained CT images and the densities of materials. Combustibles, lead, and mercury were extracted via simple segmentation based on their apparent densities. 3D feature-based discriminations were further applied to batteries and certain aluminum objects based on their structural characteristics. Almost all batteries contained in the drums were successfully discriminated regardless of deformation, except for a few cases under extreme conditions. Aluminum was extracted along with glass and concrete; however, pipes with distinctive shapes could be identified in a relatively selective manner. The discrimination methods developed in this study will be effective in revealing the contents of waste containers, particularly for harmful materials that need to be separated for proper disposal.
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。
進藤 愛美*; 上奥 あや*; 岡村 和奏*; 菊地 晋; 山崎 淳司*; 古賀 信吉*
Thermochimica Acta, 749, p.180021_1 - 180021_14, 2025/07
被引用回数：0 パーセンタイル：0.00(Thermodynamics)The present study focused on the multistep thermal dehydration/decomposition process of geopolymer paste samples prepared using distinct active fillers, including fly ash, blast furnace slag, and metakaolin. Besides the lower water content of the geopolymer materials compared with conventional Portland cement, the thermal dehydration/decomposition occurs as the multistep process. Water evolution behavior is critical for assessing its potential application as a construction material in water-resistant environment. The thermal dehydration/decomposition kinetics also plays a pivotal role in evaluating the thermal stability of geopolymer materials. This article presents the kinetic behavior of the multistep thermal dehydration/decomposition of different geopolymer materials in a stream of dry N or wet N with varying water vapor pressures. This study revealed that, irrespective of the samples, the two-step thermal dehydration/decomposition process occurred after the desorption of absorbed water. The kinetics of the initial reaction process, which is attributed to the thermal dehydration of bounded water, exhibited sensitivity to atmospheric water vapor. In contrast, the kinetics of the subsequent process of the thermal dehydroxylation of the binding phase demonstrated practically invariable behavior, irrespective of the atmospheric water vapor pressure. The latter was identified as a distinctive attribute of the irreversible process and as a pivotal process in determining the thermal stability of geopolymer materials.
柳澤 宏司; 求 惟子
JAEA-Research 2025-001, 99 Pages, 2025/06
JAEA-Research-2025-001.pdf:1.98MB
中性子吸収棒の反応度価値に関する安全検査データのより深い理解と反応度価値の測定技術の向上のために、TRIGA-ACPR(環状炉心パルス炉)に分類されるNSRR(原子炉安全性研究炉)の初回起動炉心の臨界解析用詳細計算モデルを作成した。本モデルの形状、材料、運転データの誤差から伝播する中性子実効増倍率(keff)の不確かさを、最新の核データライブラリJENDL-5及び旧版のJENDLライブラリとMVP第3版コードを用いて詳細に評価した。その結果、本モデルにおけるk
の全体的な不確かさは、0.0027から0.0029
kの範囲と評価した。本モデルは、TRIGA-ACPRのkのベンチマークとして利用されることが期待される。さらに、全体的な不確かさは、NSRRで測定された吸収棒価値よりも十分小さいことを確認した。よって、本モデルはNSRRにおける吸収棒反応度価値に関する今後の解析にも適用できる。
小川 達彦
Annals of Nuclear Energy, 216, p.111256_1 - 111256_12, 2025/06
被引用回数：0 パーセンタイル：0.00(Nuclear Science & Technology)AmBeに代表されるような、アルファ線を放出するアクチノイドと軽元素から構成される複合中性子源の性能を、多面的かつ絶対値でシミュレートできる新しい方法を開発した。この手法はモンテカルロ放射線輸送コードPHITSを用いて、
粒子用JENDL-5断面データライブラリと、ATIMAによる阻止能計算、ラティスジオメトリ計算機能を組み合わせることで、複合線源の様々な観測量を再現できる。従来の複合中性子源シミュレーション法は、測定値や近似的な断面積、多数イベントを平均した積分量などを使用するため、線源の特性パラメータ(アクチノイド粒径や線源のマクロなサイズ)を変更できなかったり、イベント内に放出される粒子間の相関を考慮できないなどの問題があったが、本手法ではそれらの問題が克服されている。この手法を用いて複合中性子源の様々な量、アクチノイド粒径依存性、中性子放出絶対強度、中性子および光子のエネルギースペクトル、中性子多重度、中性子放出の時間構造などを予測できることを示した。特に中性子の放出絶対強度とエネルギースペクトルについては、AmBe、AmF、AmB、PuBe、
CmBe、Pu
Cの6種類の線源で実験値と比較し、実験値の絶対値に不確定性があるPuBeを除いて矛盾ない結果が得られた。この方法を用いれば、複合中性子源から生じる中性子のシミュレーションにおいて、カウントレート、コインシデンスイベントの量、ガンマ線によるノイズなど、実用的な定量指標の計算が可能になる。
nanosheets for enhancing heat storage performance吉迫 大輝*; 岡本 範彦*; 田中 万也; 市坪 哲
Communications Chemistry (Internet), 8, p.169_1 - 169_9, 2025/06
被引用回数：0これまで層状マンガン酸化物の層間への水分子の脱挿入時の給排熱機構を利用した蓄熱材研究開発が進められてきた。本研究では、結晶子サイズの小さいマンガン酸化物を合成することで層間だけでなく表面への水分子吸着により蓄熱容量が増加することを示した。
