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Raman identification and characterization of chemical components included in simulated nuclear fuel debris synthesized from uranium, stainless steel, and zirconium

日下 良二; 熊谷 友多; 渡邉 雅之; 佐々木 隆之*; 秋山 大輔*; 佐藤 修彰*; 桐島 陽*

Journal of Nuclear Science and Technology, 60(5), p.603 - 613, 2023/05

 被引用回数:0 パーセンタイル:0.01(Nuclear Science & Technology)

Raman spectroscopy is a powerful technique for studying nuclear materials. However, it has been scarcely utilized for nuclear fuel debris. Here, we present a Raman study of several types of simulated nuclear debris synthesized from uranium, stainless steel, and zirconium to identify and characterize chemical components included in the simulated debris. Raman spectroscopy sensitively identified many kinds of chemical components: cubic UO$$_{2}$$, U$$_{3}$$O$$_{8}$$, (Fe,Cr)UO$$_{4}$$ (iron-chromium uranate), spinel oxides, monoclinic ZrO$$_{2}$$, tetragonal ZrO$$_{2}$$, and Zr$$_{3}$$O. Some details concerning the chemical states of each component included in the simulated debris were obtained (e.g., spinel oxides were suggested to consist of Fe, Cr, Ni, Zr, and U). The results obtained here will be helpful in the Raman analysis of actual nuclear debris, such as that in the Fukushima-Daiichi nuclear power plants.


Phase analysis of simulated nuclear fuel debris synthesized using UO$$_{2}$$, Zr, and stainless steel and leaching behavior of the fission products and matrix elements

頓名 龍太郎*; 佐々木 隆之*; 児玉 雄二*; 小林 大志*; 秋山 大輔*; 桐島 陽*; 佐藤 修彰*; 熊谷 友多; 日下 良二; 渡邉 雅之

Nuclear Engineering and Technology, 55(4), p.1300 - 1309, 2023/04

 被引用回数:0 パーセンタイル:0.02(Nuclear Science & Technology)

UO$$_{2}$$・Zr・ステンレス鋼を出発物質として模擬デブリを合成し、形成された固相の分析と浸漬試験を行った。主要なU含有相は合成条件に依存し、不活性雰囲気下・1473KではUO$$_{2}$$相が維持されていた。1873Kでは(U,Zr)O$$_{2}$$固溶体相の形成が観測された。酸化性雰囲気では、1473Kの場合にはU$$_{3}$$O$$_{8}$$と(Fe,Cr)UO$$_{4}$$相の混合物が得られ、1873Kでは(U,Zr)O$$_{2}$$が形成された。浸漬試験により金属イオンの溶出挙動を調べるため、中性子照射により核分裂生成物を導入する、もしくは出発物質への添加によりその安定同位体を導入する処理を行った。試験の結果、Uの溶出挙動は、模擬デブリの性状や浸漬液の液性に依存することが確認された。CsやSr, Baは模擬デブリの固相組成に依存せず顕著な溶出を示した。一方で、多価イオンとなるEuとRuの溶出は抑制されることが観測され、模擬デブリ中でウラン相に固溶ないしは包含されたことによる影響が推察される。


Lanthanide and actinide ion complexes containing organic ligands investigated by surface-enhanced infrared absorption spectroscopy

平田 早紀子*; 日下 良二; 明地 省吾*; 為国 誠太*; 奥寺 洸介*; 浜田 昇賢*; 坂本 知優*; 本田 匠*; 松下 高輔*; 村松 悟*; et al.

Inorganic Chemistry, 62(1), p.474 - 486, 2023/01

 被引用回数:0 パーセンタイル:0.01(Chemistry, Inorganic & Nuclear)

A new technique, surface-enhanced infrared absorption (SEIRA) spectroscopy, was used for the structural investigation of lanthanide (Ln) and actinide (An) complexes containing organic ligands. We synthesized thiol derivatives of organic ligands with coordination sites similar to those of diglycolamide (DGA), Cyanex-272, and $$N,N,N',N'$$-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN), which have been used for separating Ln and An through solvent extraction. These ligands were attached on a gold surface deposited on an Si prism through S-Au covalent bonds; the gold surface enhanced the IR absorption intensity of the ligands. Aqueous solutions of Ln (Eu$$^{3+}$$, Gd$$^{3+}$$, Tb$$^{3+}$$) and An (Am$$^{3+}$$) ions were loaded onto the gold surface to form ion complexes. The IR spectra of the ion complexes were obtained using FT-IR spectroscopy in the attenuated total reflection mode. In this study, we developed a new sample preparation method for SEIRA spectroscopy that enabled us to obtain the IR spectra of the complexes with a small amount of ion solution (5 $$mu$$L). This is a significant advantage for the IR measurement of radiotoxic Am$$^{3+}$$ complexes. In the IR spectra of DGA, the band attributed to C=O stretching vibrations at $$sim$$1630 cm$$^{-1}$$ shifted to a lower wavenumber by $$sim$$20 cm$$^{-1}$$ upon complexation with Ln and An ions. Moreover, the amount of the red-shift was inversely proportional to the extraction equilibrium constant reported in previous studies on solvent extraction. The coordination ability of DGA toward Ln and An ions could be assessed using the band position of the C=O band. The Cyanex-272- and TPEN-like ligands synthesized in this report also showed noticeable SEIRA signals for Ln and An complexes. This study indicates that SEIRA spectroscopy can be used for the structural investigation of ion complexes and provides a microscopic understanding of selective extraction of Ln and An.


Study on the relation between the crystal structure and thermal stability of FeUO$$_{4}$$ and CrUO$$_{4}$$

秋山 大輔*; 日下 良二; 熊谷 友多; 中田 正美; 渡邉 雅之; 岡本 芳浩; 永井 崇之; 佐藤 修彰*; 桐島 陽*

Journal of Nuclear Materials, 568, p.153847_1 - 153847_10, 2022/09

 被引用回数:2 パーセンタイル:63.62(Materials Science, Multidisciplinary)



Structure, stability, and actinide leaching of simulated nuclear fuel debris synthesized from UO$$_{2}$$, Zr, and stainless-steel

桐島 陽*; 秋山 大輔*; 熊谷 友多; 日下 良二; 中田 正美; 渡邉 雅之; 佐々木 隆之*; 佐藤 修彰*

Journal of Nuclear Materials, 567, p.153842_1 - 153842_15, 2022/08

 被引用回数:3 パーセンタイル:77.29(Materials Science, Multidisciplinary)

福島第一原子力発電所事故では、UO$$_{2}$$やZr,ステンレス鋼(SUS)の高温反応により燃料デブリが形成されたとみられる。この燃料デブリの化学構造や安定性を理解するため、UO$$_{2}$$-Zr-SUS系模擬デブリ試料の合成と物性評価を行い、より単純な組成の試料と比較した。模擬デブリ試料の合成では、不活性雰囲気(Ar)もしくは酸化雰囲気(Ar + 2% O$$_{2}$$)において1600$$^{circ}$$Cで1時間から12時間の加熱処理を行った。$$^{237}$$Npおよび$$^{241}$$Amをトレーサーとして添加し、浸漬試験ではUに加えてこれらの核種の溶出を測定した。試料の物性評価は、XRD, SEM-EDX,ラマン分光法およびメスバウアー分光法により行った。その結果、模擬デブリの主なU含有相は、加熱処理時の雰囲気に依らず、Zr(IV)およびFe(II)が固溶したUO$$_{2}$$相であることが分かった。模擬デブリ試料の純水もしくは海水への浸漬試験では、1年以上の浸漬の後も主な固相の結晶構造には変化が観測されず、化学的に安定であることが示された。さらに、U, Np, Amの溶出率はいずれも0.08%以下と、溶出は極めて限定的であることが明らかとなった。


Uranium dissolution and uranyl peroxide formation by immersion of simulated fuel debris in aqueous H$$_{2}$$O$$_{2}$$ solution

熊谷 友多; 日下 良二; 中田 正美; 渡邉 雅之; 秋山 大輔*; 桐島 陽*; 佐藤 修彰*; 佐々木 隆之*

Journal of Nuclear Science and Technology, 59(8), p.961 - 971, 2022/08

 被引用回数:2 パーセンタイル:63.62(Nuclear Science & Technology)



Development of heavy element chemistry at interfaces; Observing actinide complexes at the oil/water interface in solvent extraction by nonlinear vibrational spectroscopy

日下 良二; 渡邉 雅之

Journal of Physical Chemistry Letters (Internet), 13(30), p.7065 - 7071, 2022/08

 被引用回数:2 パーセンタイル:61.67(Chemistry, Physical)

Understanding the chemistry of elements at the bottom of the periodic table is a challenging goal in chemistry. Observing actinide species at interfaces using interface-selective second-order nonlinear optical spectroscopy, such as vibrational sum frequency generation (VSFG) spectroscopy, is a promising route for developing heavy element chemistry; however, such attempts are scarce. Here, we investigated the phase transfer mechanism of uranyl ions (UO$$_{2}$$$$^{2+}$$) in solvent extraction using the di-(2-ethylhexyl)phosphoric acid (HDEHP) extractant dissolved in dodecane organic phase by probing the oil/water liquid-liquid interface using VSFG spectroscopy. The POO$$^{-}$$ symmetric stretch vibrational signals of the HDEHP ligands clearly demonstrated that uranyl ions form interfacial complexes with HDEHP at the oil/water interface. The interfacial uranyl-HDEHP complexes were formed with uranyl ions coming from both the aqueous and oil phases, strongly suggesting that the interfacial complex is an intermediate to cross the oil/water interface. Density functional theory (DFT) calculations proposed the molecular structure of the interfacial uranyl-HDEHP complex.



熊谷 友多; 日下 良二; 中田 正美; 渡邉 雅之; 秋山 大輔*; 桐島 陽*; 佐藤 修彰*; 佐々木 隆之*

放射線化学(インターネット), (113), p.61 - 64, 2022/04



Distribution of studtite and metastudtite generated on the surface of U$$_{3}$$O$$_{8}$$; Application of Raman imaging technique to uranium compound

日下 良二; 熊谷 友多; 蓬田 匠; 高野 公秀; 渡邉 雅之; 佐々木 隆之*; 秋山 大輔*; 佐藤 修彰*; 桐島 陽*

Journal of Nuclear Science and Technology, 58(6), p.629 - 634, 2021/06

 被引用回数:7 パーセンタイル:70.19(Nuclear Science & Technology)

Studtite and metastudtite are uranyl peroxides formed on nuclear fuel in water through the reaction with H$$_{2}$$O$$_{2}$$ produced by the radiolysis of water. However, it is unclear how the two types of uranyl peroxides are generated and distributed on the surface of nuclear fuel. Here, we used Raman imaging technique to exemplify distribution data of the two uranyl peroxides formed on the surface of a U$$_{3}$$O$$_{8}$$ pellet through immersion in a H$$_{2}$$O$$_{2}$$ aqueous solution. As a result, we observed that studtite and metastudtite are heterogeneously distributed on the U$$_{3}$$O$$_{8}$$ surface. No clear correlation between the distributions of studtite and metastudtite was observed, suggesting that the two uranyl peroxides are independently generated on the surface of U$$_{3}$$O$$_{8}$$. We anticipate that this Raman imaging technique could reveal how these uranyl peroxides are generated and distributed on the surface of the nuclear fuel debris in the Fukushima-Daiichi Nuclear Power Plants.


Stoichiometry of lanthanide-phosphate complexes at the water surface studied using vibrational sum frequency generation spectroscopy and DFT calculations

日下 良二; 渡邉 雅之

Journal of Physical Chemistry B, 125(24), p.6727 - 6731, 2021/06

 被引用回数:8 パーセンタイル:50.56(Chemistry, Physical)

In the solvent extraction of metal ions, the transport mechanism of metal ions through the liquid-liquid organic/aqueous interface remains unclear. In this study, the adsorption process of trivalent lanthanide ions from the aqueous phase to the interface in the solvent extraction of lanthanides with di(2-ethylhexyl)phosphoric acid (HDEHP) extractant is investigated by using a model interface - water surface covered with HDEHP (air/HDEHP/aqueous interface). As a result, symmetric POO$$^{-}$$ stretch signals of HDEHP observed by vibrational sum frequency generation spectroscopy and density functional theory calculations show that the stoichiometric ratio of lanthanide-HDEHP complexes formed at the air/HDEHP/aqueous interface is 1:1. The formation of the interfacial 1:1 lanthanide-HDEHP complex could be an elementary chemical process occurring just before the transfer of lanthanide ions to the side of the organic phase.


Role of advection in atmospheric ammonia; A Case study at a Japanese lake basin influenced by agricultural ammonia sources

久保田 智大; 黒田 久雄*; 渡邊 未来*; 高橋 晃子*; 中里 亮治*; 樽井 美香*; 松本 俊一*; 中川 圭太*; 沼田 康子*; 大内 孝雄*; et al.

Atmospheric Environment, 243, p.117856_1 - 117856_9, 2020/12

 被引用回数:2 パーセンタイル:11.13(Environmental Sciences)



Application of photoluminescence microspectroscopy; A Study on transfer of uranyl and europium ions on dry silica gel plate

日下 良二; 渡邉 雅之

Journal of Nuclear Science and Technology, 57(9), p.1046 - 1050, 2020/09

 被引用回数:0 パーセンタイル:0.01(Nuclear Science & Technology)

When water contacts with porous materials, water and chemical species dissolved in the water transfer into the inside of the porous materials. Here, to study the transfer of uranyl and europium ions on a dry silica gel plate, we dropped a small amount of aqueous solution ($$sim$$0.5 $$mu$$L) dissolving the two ions on a dry silica gel plate, and the distributions of the two ions spread on the silica gel plate were observed by photoluminescence microspectroscopy. Photoluminescence images of uranyl and europium ions clearly show that when uranyl ion coexists in the solution, europium ion distributes in a larger area compared to uranyl ion. It can be interpreted that the larger-area distribution of europium ion is caused because uranyl ion is preferentially adsorbed to silica gel and the uranyl adsorption disturbs the adsorption of europium ion. The coexistence of uranyl ion may influence the mobility of other ion species.


Extraction mechanism of lanthanide ions into silica-based microparticles studied by single microparticle manipulation and microspectroscopy

大高 稔紀*; 佐藤 辰巳*; 大野 真平; 名越 航平; 安倍 諒治*; 新井 剛*; 渡部 創; 佐野 雄一; 竹内 正行; 中谷 清治*

Analytical Sciences, 35(10), p.1129 - 1133, 2019/10

 被引用回数:7 パーセンタイル:34.17(Chemistry, Analytical)

Single porous silica microparticles coated with styrene-divinylbenzene polymer (SDB) impregnated with octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) were injected into an aqueous 3 mol/L nitric acid solution containing trivalent lanthanide (Ln(III)), as a high-level liquid waste model, using the microcapillary manipulation-injection technique; and the extraction rate of Ln(III), as an Ln(III)-CMPO complex, into the single microparticles was measured by luminescence microspectroscopy. The extraction rate significantly depended on the Ln(III), CMPO, or NO$$_{3}$$$$^{-}$$ concentration, and was analyzed in terms of diffusion in the pores of the microparticles and complex formation of Ln(III). The results indicated that the rate-determining step in Ln(III) extraction was the diffusion in the pore solution of the microparticles.


Mechanism of phase transfer of uranyl ions; A Vibrational sum frequency generation spectroscopy study on solvent extraction in nuclear reprocessing

日下 良二; 渡邉 雅之

Physical Chemistry Chemical Physics, 20(47), p.29588 - 29590, 2018/12

 被引用回数:17 パーセンタイル:69.73(Chemistry, Physical)



The Structure of a lanthanide complex at an extractant/water interface studied using heterodyne-detected vibrational sum frequency generation

日下 良二; 渡邉 雅之

Physical Chemistry Chemical Physics, 20(4), p.2809 - 2813, 2018/01

 被引用回数:14 パーセンタイル:62.6(Chemistry, Physical)



Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

中島 健次; 川北 至信; 伊藤 晋一*; 阿部 淳*; 相澤 一也; 青木 裕之; 遠藤 仁*; 藤田 全基*; 舟越 賢一*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12



Microscopic analyses of complexes formed in adsorbent for Mo and Zr separation chromatography

安倍 諒治*; 名越 航平*; 新井 剛*; 渡部 創; 佐野 雄一; 松浦 治明*; 高木 秀彰*; 清水 伸隆*; 江夏 昌志*; 佐藤 隆博*

Nuclear Instruments and Methods in Physics Research B, 404, p.173 - 178, 2017/08

 被引用回数:5 パーセンタイル:46.25(Instruments & Instrumentation)

Molybdenum and zirconium obstruct the efficient recovery of minor actinides (MA(III): Am(III) and Cm(III)) by extraction chromatography; hence, the removal of these elements prior to MA(III) recovery is desirable. The use of an adsorbent impregnated with bis(2-ethylhexyl) hydrogen phosphate (HDEHP) for Mo and Zr decontamination was evaluated in this report. The adsorption/elution and column separation experiments showed that Mo and Zr in the simulated HLLW were selectively adsorbed on the particles, and that Mo was eluted by H$$_{2}$$O$$_{2}$$. EXAFS analysis and SAXS patterns of the adsorbent containing Zr revealed that the Zr-HDEHP complex had a crystal-like periodic structure similar to the structure of the precipitate produced in the solvent extraction system. Micro-PIXE analysis revealed that distribution of the residual Zr on the adsorbent was uniform.


Study on the deterioration mechanism of layered rock-salt electrodes using epitaxial thin films; Li(Ni, Co, Mn)O$$_{2}$$ and their Zr-O surface modified electrodes

阿部 真知子*; 射場 英紀*; 鈴木 耕太*; 南嶋 宏映*; 平山 雅章*; 田村 和久; 水木 純一郎*; 齋藤 智浩*; 幾原 雄一*; 菅野 了次*

Journal of Power Sources, 345, p.108 - 119, 2017/03

 被引用回数:11 パーセンタイル:39.99(Chemistry, Physical)

Ni, Co, Mn三元系リチウムイオン電池正極材料について、その劣化機構について、電気化学測定、X線・中性子線測定により調べた。実験の結果、Ni, Co, Mn三元系正極は、層状岩塩型構造とスピネル構造で構成されており、充放電を繰り返すと、充放電に関与しないスピネル構造が表面を覆っていくことが分かった。一方で、Zr-Oで表面をコートした材料は劣化しないことが知られており、その原因を調べた結果、層状岩塩型構造が安定に存在し続けていることが分かった。さらに、電極/溶液界面のLi濃度を上昇していることも分かった。


Magnetoelectric coupling in the honeycomb antiferromagnet Co$$_{4}$$Nb$$_{2}$$O$$_{9}$$

Khanh, N. D.*; 阿部 伸行*; 佐賀山 基*; 中尾 朗子*; 花島 隆泰*; 鬼柳 亮嗣; 徳永 祐介*; 有馬 孝尚*

Physical Review B, 93(7), p.075117_1 - 075117_6, 2016/02

 被引用回数:94 パーセンタイル:95.21(Materials Science, Multidisciplinary)

The magnetic structure and magnetoelectric effect have been investigated for single crystals of the antiferromagnet Co$$_{4}$$Nb$$_{2}$$O$$_{9}$$. Single-crystal neutron diffraction and magnetic susceptibility measurement have revealed that the magnetic structure is different from a collinear arrangement with spin parallel to the trigonal axis as proposed previously. Co$$^{2+}$$ magnetic moments are found to be almost lying in the basal plane, which lowers the magnetic symmetry to $$C2/c'$$ with the propagation vector $$k$$ = 0. Associated with the magnetic phase transition, a sharp anomaly in the dielectric constant and displacement current indicate the appearance of the magnetoelectric below Neel temperature TN with a large coupling constant up to 30 ps/m. The existence of off-diagonal components in a magnetoelectric tensor indicate the formation of ferrotoroidic order in Co$$_{4}$$Nb$$_{2}$$O$$_{9}$$. Such a magnetoelectric effect can be ascribed to the reduction of symmetry caused by simple antiferromagnetic order in a honeycomb network.


Changes to the chemical structure of isotactic-polypropylene induced by ion-beam irradiation

岡 壽崇; 大島 明博*; 本橋 良太*; 瀬戸 直人*; 渡邊 裕司*; 小林 亮二*; 斉藤 功樹*; 工藤 久明*; 村上 健*; 鷲尾 方一*; et al.

Radiation Physics and Chemistry, 80(2), p.278 - 280, 2011/02

 被引用回数:7 パーセンタイル:49.49(Chemistry, Physical)


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