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熊田 高之; 元川 竜平; 大場 洋次郎; 中川 洋; 関根 由莉奈; Micheau, C.; 上田 祐生; 杉田 剛; 美留町 厚; 佐々木 未来; et al.
Journal of Applied Crystallography, 56(6), p.1776 - 1783, 2023/12
被引用回数：1 パーセンタイル：60.87(Chemistry, Multidisciplinary)既存のメイン検出器および高位置分解能フォトマル検出器に加えて新規に導入した前面検出器を組み合わせることにより、波数0.002nm
から6nmにわたる散乱を3つの光学機器配置により切れ目なく測定できるようになった。またグラフィカルユーザーインターフェースの導入と併せて装置のユーザビリティが大幅に向上した。
川口 真穂*; 柴 茂樹*; 岩橋 大希*; 大川 剛*; 郡司 智; 井澤 一彦; 須山 賢也
Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 8 Pages, 2023/10
原子力規制委員会は、2014年から日本原子力研究開発機構(JAEA)と共同で、福島第一原子力発電所事故で発生した燃料デブリの臨界性を評価するための実験的アプローチに取り組んでいる。その一環として、擬似燃料デブリの特性を評価する臨界実験を実施するため、原子力機構は臨界実験装置STACY(STAtic experiment Critical facilitY)を改良した。予備解析として、提案した炉心配置パターンについて、主要な核データライブラリを用いて臨界特性を検証した。3次元連続エネルギーモンテカルロ中性子・光子輸送コードSERPENT-V2.2.0と最新のJENDL-5を用いた。その結果、STACY更新炉の炉心配置パターン全てにおいてJENDL-5による中性子増倍率は、他のライブラリを使用した結果と比較して大きく評価された。また、JENDL-5の
H散乱反応及び
U核分裂反応断面積の感度係数は他のライブラリとは異なっていた。これらのライブラリとの比較から、JENDL-5の更新されたS(
, 
)は、STACY更新炉の臨界特性の評価結果に影響を与える可能性があることがわかった。
柴 茂樹*; 岩橋 大希*; 大川 剛*; 郡司 智; 井澤 一彦; 須山 賢也
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 9 Pages, 2023/05
原子力規制委員会は2014年より日本原子力研究開発機構と共同して実際の燃料デブリを模擬した模擬燃料デブリの臨界性を判断するための実験に取り組んでいる。日本原子力研究開発機構は模擬燃料デブリの特性を解明することを目的とした燃料デブリを模擬した臨界実験を実施するためSTACY(STAtic experiment Critical facilitY)を改造した。そこでは3種類のSTACY更新炉の炉心構成が提案されている。STACY更新炉での臨界実験では、提案した炉心構成が溶融炉心-コンクリート相互作用デブリを代表するものかどうかを判断することが重要である。本研究では、擬似燃料デブリと減速材の体積比(V
/V
)を考慮した擬似燃料デブリ・モデルを構築し、SCALE6.2の感度及び不確かさ解析手法の実装のためのツール-指標及びパラメータ(Tools for Sensitivity and Uncertainty Analysis Methodology Implementation-Indices and Parameters: TSUNAMI-IP)を用いて、修正STACY炉心形状と疑似燃料デブリ・モデルの間の不確かさに基づく類似性値(C
)の算出を行った。その結果、我々が提案したSTACY更新炉の炉心に装荷される構造材棒は、V/V値を通じて疑似燃料デブリ模型と高い類似性を持つことが示された。C値への主な寄与は、極めて高いコンクリート成分を含む疑似燃料デブリモデルを除き、
U 
, U 
, 
Fe (n,
)であった。
成田 弘一*; Nicolson, R. M.*; 元川 竜平; 伊藤 文之*; 森作 員子*; 後藤 みどり*; 田中 幹也*; Heller, W. T.*; 塩飽 秀啓; 矢板 毅; et al.
Inorganic Chemistry, 58(13), p.8720 - 8734, 2019/07
被引用回数：14 パーセンタイル：69.15(Chemistry, Inorganic & Nuclear)Current industrial practices to extract rhodium from virgin ores carry a heavy environmental burden. Improving the efficiency of the hydrometallurgical processes to separate and recover rhodium from other precious metals provides an opportunity to improve the materials and energy balances, but the presence of mixed chloride-rhodium species following leaching by acid chloride media complicates the recovery process. In this work we have applied a broad range of analytical techniques (FT-IR spectroscopy, X-ray diffraction, EXAFS, water-transfer analysis, small-angle neutron scattering, NMR spectroscopy, and electrospray mass spectrometry), which together show that the amino-amide reagent preferentially transports chlorido-rhodium species as a 1:2 neutral assembly from aqueous 2.0 M HCl phase into an organic phase. The extractants then ligate in the outer coordination shell of the chloride-rhodium anion, making this an efficient separation process. In this study, we found that protonation to the extractants induced to form a proton chelate ring, which pre-organises the ligand to present an array of charge diffuse C-H bonds. This templated arrangement of positive dipoles favors complexation to the charge diffuse chloride-rhodium anion over the more charge-dense chloride anion.
solution; Comparison with tri-
-butyl phosphate上田 祐生; 菊池 圭; 杉田 剛; 元川 竜平
Solvent Extraction and Ion Exchange, 37(5), p.347 - 359, 2019/07
被引用回数：8 パーセンタイル：33.64(Chemistry, Multidisciplinary)リン酸トリブチル(TBP)を用いた従来のPUREXプロセスにおいて多量のZr(IV)が含まれる場合、抽出錯体,遊離の抽出剤,酸、および水の凝集を起源として生成する不溶性の第三相や沈殿による目的物の抽出阻害が問題であった。本研究では水にほとんど溶解しないフルオラス化合物に着目し、TBPと同一のリン酸エステル構造を有するフルオラスリン酸エステル抽出剤を合成し、本抽出剤のZr(IV)抽出特性,抽出機構、および第三相生成の抑制効果をTBPと比較検証した。開発した新規抽出剤は、TBPと比較し第三相の生成を著しく抑制するとともに、幅広い硝酸濃度領域においてTBPよりも高いZr(IV)抽出能力を示すことが明らかとなった。
成田 弘一*; 前田 泰生*; 所 千晴*; 鈴木 智也*; 田中 幹也*; 元川 竜平; 塩飽 秀啓; 矢板 毅
Analytical Sciences, 33(11), p.1305 - 1309, 2017/11
被引用回数：11 パーセンタイル：40.32(Chemistry, Analytical)Using 
-tetra-2-ethylhexyl-thiodiglycolamide (TEHTDGA) in -dodecane as the extractant, we compared the percentages of Pd(II) extracted from HCl and HBr solutions, and analyzed the structures of the Pd(II)-extractant complexes. TEHTDGA rapidly extracted Pd(II) from both HCl and HBr solutions, predominantly by formation of a 1:2 Pd(II)/TEHTDGA complex. The extractability of Pd(II) from HBr solution was inferior to that from HCl solution. FT-IR spectroscopy and EXAFS measurements indicated that two of the halide ions in the tetrachloro- or tetrabromopalladate(II) ions were replaced by the sulfur atoms of two TEHTDGA molecules. In the [PdBr
(TEHTDGA)] complex, the Pd-S bond was shorter than the Pd-Br bond. We suggest that this bond length difference resulted in greater steric hindrance during coordination of TEHTDGA to the Pd(II) atom in the HBr system than in the HCl system, leading to the lower extractability in the HBr system.
久松 秀悟; 鈴木 伸一; 幸本 重男*; 岸川 圭希*; 山本 雄介*; 元川 竜平; 矢板 毅
Tetrahedron, 73(27-28), p.3993 - 3998, 2017/07
被引用回数：15 パーセンタイル：57.31(Chemistry, Organic)A sensory system incorporated with an amplification function was developed for detection of trace-level fluoride ions. This sensory system comprises two steps, namely, amplification, and chemiluminescence. These steps were linked with chemical reactions and were induced continuously. The process from amplification to chemiluminescence was accomplished in the system by using fluoride ions. The amplification was based on a self-immolative system, which permitted the detection of emissions even at low fluoride ion concentration for system in which chemiluminescence cannot be induced in the absence of fluoride ions. An optical ratio of the chemiluminescent compound and the amplifier was calculated for achieving efficient amplification.
前田 泰生*; 成田 弘一*; 所 千晴*; 田中 幹也*; 元川 竜平; 塩飽 秀啓; 矢板 毅
Separation and Purification Technology, 177, p.176 - 181, 2017/04
被引用回数：22 パーセンタイル：58.37(Engineering, Chemical)The separation properties of Pt(IV) over Fe(III) in HCl solutions using 
-2-ethylhexyl-bis(-di-2-ethylhexyl-ethylamide)amine (EHBAA) were investigated and then compared with those using the conventional extractant tri--octylamine (TOA). Also, the structural analyses of Pt(IV) in both of the aqueous (HCl solution) and organic (EHBAA in -dodecane-2-ethylhexanol solution) phases were performed with EXAFS spectroscopy. The extractability of Pt(IV) was much higher with EHBAA than with TOA in the studied HCl concentration range (0.2-0.8 M HCl); additionally, EHBAA selectively extracted Pt(IV) over Fe(III) under the condition of [EHBAA] 
0.1 M and [HCl] 1 M. The Pt(IV) loading capacity of 0.1 M EHBAA was about 9.2 g/L (about 0.05 M). Most of the Pt(IV) extracted with 0.1 M EHBAA from 1 M HCl was stripped with 0.1 M NaOH; the co-extracted Fe(III) was selectively scrubbed with distilled water. The structural studies indicated that the Pt(IV) extracted with EHBAA from 1 M HCl formed an ion-pair complex, [PtCl
]
(EHBAAH).
元川 竜平; 小林 徹; 遠藤 仁*; 池田 隆司; 矢板 毅; 鈴木 伸一; 成田 弘一*; 阿久津 和宏*; Heller, W. T.*
Journal of Nuclear Science and Technology, 53(8), p.1205 - 1211, 2016/08
被引用回数：0 パーセンタイル：0.01(Nuclear Science & Technology)This study uses small-angle neutron scattering (SANS) to elucidate the coordination structure of the complex of mono-acetyl substituted dibenzo-20-crown-6-ether (ace-DB20C6) with Cs. SANS profiles obtained for the complex of ace-DB20C6 and Cs (ace-DB20C6/Cs) in deuterated dimethyl sulfoxide indicated that Cs coordination resulted in a more compact structure than the free ace-DB20C6. The data were fit well with SANS profiles calculated using Debye function for scattering on an absolute scattering intensity scale. For this theoretical calculation of the scattering profiles, the coordination structure proposed based on a density functional theory calculation. Consequently, we conclude that the SANS analysis experimentally supports the proposed coordination structure of ace-DB20C6/Cs and suggests the following: (1) the complex of ace-DB20C6 and Cs is formed with an ace-DB20C6/Cs molar ratio of 1/1; (2) the two benzene rings of ace-DB20C6 fold around Cs above the center of the crown ether ring of ace-DB20C6.
元川 竜平; 遠藤 仁*; 横山 信吾*; 小川 紘樹*; 小林 徹; 鈴木 伸一; 矢板 毅
Langmuir, 30(50), p.15127 - 15134, 2014/12
被引用回数：27 パーセンタイル：63.28(Chemistry, Multidisciplinary)The effect of cesium (Cs) adsorption on the mesoscopic structure of the clay minerals vermiculite and weathered biotite (WB) in suspensions was elucidated by small-angle X-ray scattering (SAXS). The clay minerals form multilayered structures and the Cs cations are strongly adsorbed in the interlayer space of the soil clays, in particular vermiculite and WB. SAXS was used to monitor the relationship between Cs adsorption at the clay interlayers and the structural changes at length scales from 0.1 to 100 nm. The variation in the distance between the neighboring clay sheets and the spatial arrangement of the clay sheets with and without Cs were clarified. Our quantitative analyses revealed that the number of stacked layers of pure vermiculite was decreased by Cs addition, whereas that of WB increased. Moreover, the average distance between the neighboring layers of vermiculite in suspension was larger than that of WB, which reflects the different conditions of Cs intercalation. These findings provide fundamental insights that are important for predicting the environmental fate of radioactive cesium in contaminated regions and for developing methods for extracting cesium from soil.
元川 竜平; 遠藤 仁*; 横山 信吾*; 西辻 祥太郎*; 小林 徹; 鈴木 伸一; 矢板 毅
Scientific Reports (Internet), 4, p.6585_1 - 6585_6, 2014/10
被引用回数：36 パーセンタイル：70.93(Multidisciplinary Sciences)Following the Fukushima Daiichi nuclear disaster in 2011, Cs radioisotopes have been dispersed over a wide area. Most of the Cs has remained on the surface of the soil because Cs is strongly adsorbed in the interlayer spaces of soil clays, particularly vermiculite. We have investigated the microscopic structure of an aqueous suspension of vermiculite clay over a wide length scale (0.1-100 nm) by small-angle X-ray scattering. We determined the effect of the adsorption behavior of Cs on the structural changes in the clay. It was found that the abruption of the clay sheets was induced by the localization of Cs at the interlayer. This work provides important information for predicting the environmental fate of radioactive Cs in polluted areas, and for developing methods to extract Cs from the soil and reduce radioactivity.
Awual, M. R.; 小林 徹; 塩飽 秀啓; 宮崎 有史; 元川 竜平; 鈴木 伸一; 岡本 芳浩; 矢板 毅
Chemical Engineering Journal, 225, p.558 - 566, 2013/06
被引用回数：198 パーセンタイル：98.67(Engineering, Environmental)This study was investigated the trace lanthanide (Nd(III), Eu(III) and Yb(III)) sorption and recovery from wastewater streams by novel hybrid adsorbent. The experiments were investigated to determine the effects pH, ions selectivity and lanthanide ions coordination by XAFS spectra. The EXAFS data revealed that O and N donor atoms of the HA were strongly coordinated to lanthanide ions to form stable complexes. However, the bond distance of O donor atoms was shorter than N donor atoms.
Awual, M. R.; 小林 徹; 宮崎 有史; 元川 竜平; 塩飽 秀啓; 鈴木 伸一; 岡本 芳浩; 矢板 毅
Journal of Hazardous Materials, 252-253, p.313 - 320, 2013/05
被引用回数：185 パーセンタイル：97.62(Engineering, Environmental)The oxygen and nitrogen donor atoms containing Lewis base N-methyl-N-phenyl-1,10-phenanthroline-2-carboxamide (MePhPTA) ligand was synthesized and subsequently an adsorbent was prepared by direct immobilization onto mesoporous silica. The crystallography for the Sm-MePhPTA complex suggested that MePhPTA was strongly coordinated to Sm(III) with oxygen and nitrogen by forming a stable complex with two 5-membered rings. The data clarified that bond lengths between Sm(III) and amide oxygen (2.475 
) were shorter than Sm-N (2.662 ) in phenanthroline moiety indicating strong oxygen driven adsorbent.
-butyl phosphate/-octane mixtures by X-ray and neutron scattering in a wide 
range元川 竜平; 鈴木 伸一; 小川 紘樹*; Antonio, M. R.*; 矢板 毅
Journal of Physical Chemistry B, 116(4), p.1319 - 1327, 2012/02
被引用回数：36 パーセンタイル：65.39(Chemistry, Physical)Tri--butyl phosphate (TBP) is an important extractant for separating hexavalent uranium and tetravalent plutonium from used nuclear fuel by solvent extraction. In such solvent extractions using TBP, the organic phase occasionally separates into two organic phases, namely, light and heavy organic phases. The latter one in particular is called the third phase. The purpose of this work is to elucidate the mechanism whereby the third phase forms in biphasic liquid-liquid solvent extraction of heavy metal ions. Toward this end, small- and wide-angle X-ray and neutron scattering experiments were conducted to examine the microscopic structures of TBP/octane mixtures. These investigations of solute associations provide insights into system performance. After the extraction of heavy metal ions, for example, the microscopic structures formed in the organic phase are likely to be correlated with the initial microscopic structures, which are revealed here. SWAXS and SWANS, with accurate estimations of incoherent scattering intensities for all solution samples, revealed the following: (1) TBP self-associates in octane, and the average distance between two TBP molecules in the TBP assemblies is evaluated as 0.9-1.0 nm; (2) the shape of the TBP assembly is ellipsoidal; and (3) the attractive interaction among TBP assemblies in octane is miniscule, and thus, they tend to be dispersed homogeneously due to the excluded volume effect.
寺島 崇矢*; 元川 竜平; 小泉 智*; 澤本 光男*; 上垣外 正己*; 安藤 剛*; 橋本 竹治*
Macromolecules, 43(19), p.8218 - 8232, 2010/10
被引用回数：42 パーセンタイル：77.44(Polymer Science)
and time-resolved small-angle neutron scattering (SANS) was employed for the elucidation of star polymer formation mechanism via linking reaction of living linear polymers in ruthenium-catalyzed living radical polymerization. Here, methyl methacrylate (MMA) was first polymerized with R-Cl/RuCl(PPh)/tribuylamine (-BuN) initiating system, followed by the addition of ethylene glycol dimethacrylate (EGDMA: 3) as a linking agent. After the in situ addition of a small amount of 3 to living linear PMMA, the SANS analysis revealed the following three steps: (process II-1) formation of block copolymers (4) and competitive formation of the small star polymers via the linking reaction of 4 and 4; (process II-2) star-star linking of the small star polymers into star polymers and putting 4 into the core of the star polymers, leading to formation of the microgel-core star polymers; (process II-3) growth of the microgelcore star polymers (5) via placement of 4 into the microgel-core star polymers. Furthermore, the SANS profiles, obtained as a function of polymerization time, were quantitatively analyzed with a core-shell spherical model in order to determine the microstructures of the star polymers: The final reaction product had an average radius of microgel-core (
1 nm), and average arm numbers N 17.
古賀 毅*; 田中 文彦*; 元川 竜平; 小泉 智*; Winnik, F. M.*
Macromolecular Symposia, 291-292(1), p.177 - 185, 2010/05
被引用回数：4 パーセンタイル：60.27(Polymer Science)We developed a theoretical model for a self-assembling telechelic poly(Nisopropylacrylamide) (PNIPAM) carrying octadecyl end-groups in aqueous solution, as a function of temperature and concentration, on the basis of small-angle neutron scattering data. In solutions of concentration 10 gL at temperatures between 10 and 20 
C, the telechelic PNIPAM of molecular weight of 22200 gmol associates in the form of flower micelles containing about 12 polymer chains. Micelles have a 3-layered core-shell morphology with an inner core consisting of the octadecyl units, a dense inner shell consisting of partly collapsed PNIPAM chains, and an outer shell of swollen hydrated PNIPAM chains. Drastic changes in the scattering profile of the solution heated above 31 C are attributed to the formation of mesoglobules of diameter of 100 nm consisting of about 1000 polymer chains. In solutions of lower concentration (1 gL), association of flower micelles and mesoglobules is suppressed. The structure of the individual flower micelles and mesoglobules is not affected by changes in concentration. In solutions of 50 gL, a peak attributed to a correlation between flower micelles appears in the scattering profiles at low temperature (10 C). Despite the difference in the population of intermicellar bridges, the overall temperature dependence of the scattering profile at 50 gL remains similar to that at 10 gL.
古賀 毅*; 田中 文彦*; 元川 竜平; 小泉 智; Winnik, F. M.*
Macromolecules, 41(23), p.9413 - 9422, 2008/11
被引用回数：73 パーセンタイル：89.27(Polymer Science)ポリ(N-イソプロピルアクリルアミド)(PNIPAM)の両端末を、オクタデシル基で疎水化したテレケリックPNIPAM(HM-PNIPAM)の水溶液は、温度変化に応答してフラワーミセルやメソグロビュール(会合構造)を形成する。この水溶液は、温度とポリマー濃度の変化に応じて、ゾル-ゲル転移や水溶液の白濁等のマクロな状態を変化させる。本論文では、この水溶液に対して中性子小角散乱測定を行い、その結果に対して理論モデルを組み立てることで、マクロな状態変化に伴うメソスケールでの構造変化(ミクロな構造変化)を明らかにした。これにより、マクロな状態変化のメカニズムを明らかにすると同時に、さまざまな温度,ポリマー濃度条件で形成されるフラワーミセルやメゾグロビュールのサイズ,形状を決定した。
大川 剛; Greenspan, E.*
Nuclear Technology, 160(3), p.257 - 278, 2007/12
被引用回数：0 パーセンタイル：0.01(Nuclear Science & Technology)米国DOEが推進するGENERATION-4に選定されている鉛ビスマス冷却金属燃料のENHS(原子力バッテリー)は、現在までの設計では、正の冷却材ボイド反応度を持っている。そのため、安全性をさらに向上させるために、負のボイド反応度を持つことが可能かどうかについて、パラメータサーベイを実施した。
Mn
NHwang, J. I.*; 石田 行章*; 小林 正起*; 平田 玄*; 田久保 耕*; 溝川 貴司*; 藤森 淳; 岡本 淳; 間宮 一敏*; 斎藤 祐児; et al.
Physical Review B, 72(8), p.085216_1 - 085216_6, 2005/08
被引用回数：65 パーセンタイル：88.06(Materials Science, Multidisciplinary)常磁性GaMnNの電子構造について光電子分光(PES),X線吸収分光(XAS)によって調べた。XAS実験スペクトルを理論計算と比較することによって、GaN中Mnは正四面体配位結晶場中の2価で説明できることがわかった。この結果に従い、Mn2p及びMn3d光電子スペクトルを配置間相互作用クラスターモデルで解析した。これにより見積もられた電子構造パラメータから計算したp-d交換相互作用定数の大きさはGaMnAsの1.6倍であることが判明した。また、内殻PESからはMn濃度の上昇に伴ってフェルミレベルが降下する様子とバンドギャップ中に新たな状態が生成され増大する様子が観測された。以上のことから、GaMnNにおいて十分な正孔濃度を実現することで高い転移点を持つ強磁性が発現する可能性が実験的に示された。
大川 剛; Greenspan, E.*
ANS 2004 Winter Meeting, 1(1), 31 Pages, 2004/00
米国DOEが推進するGENERATION-4に選定されている鉛ビスマス冷却金属燃料のENHS(原子力バッテリー)の代替炉心について検討した設計研究成果を発表する。本検討では、ステップ形状炉心をENHSの炉心に適用し、高速炉の安全性に深くかかわるボイド反応度を負にする検討を行った。更に、半径方向出力ピーキングが比較的大きいため、これを低減させる検討も同時に実施した。
