Francisco, P. C. M.; Mitsui, Seiichiro; Ishidera, Takamitsu; Tachi, Yukio; Doi, Reisuke; Shiwaku, Hideaki
Geochimica et Cosmochimica Acta, 270, p.1 - 20, 2020/02
Nagai, Takayuki; Sasage, Kenichi; Okamoto, Yoshihiro; Shiwaku, Hideaki; Yamagishi, Hirona*; Ota, Toshiaki*; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*; Takahashi, Tomoe*; et al.
JAEA-Research 2019-003, 94 Pages, 2019/09
The local structures of glass-forming elements and waste elements would change by the chemical composition of waste glass including those elements. In this study, simulated waste glass samples were prepared from borosilicate glass frit including phosphorus (P) or vanadium (V), and we investigated local structures of boron, sodium, and waste elements in these P glass and V glass samples by using synchrotron XAFS measurements in soft and hard X ray region.
Narita, Hirokazu*; Nicolson, R. M.*; Motokawa, Ryuhei; Ito, Fumiyuki*; Morisaku, Kazuko*; Goto, Midori*; Tanaka, Mikiya*; Heller, W. T.*; Shiwaku, Hideaki; Yaita, Tsuyoshi; et al.
Inorganic Chemistry, 58(13), p.8720 - 8734, 2019/07
Okamoto, Yoshihiro; Nagai, Takayuki; Shiwaku, Hideaki; Kano, Shigeru; Himeno, Haruyuki*; Kobayashi, Hiroshi*; Nakatani, Mikio*
JAEA-Research 2018-013, 18 Pages, 2019/03
The chemical state and local structure of some elements in the simulated nuclear waste glass samples (20 batches) prepared by bottom drain test in the full scale mock-up tests using KMOC melter were investigated by synchrotron radiation based X-ray absorption fine structure (XAFS) analysis. As a result of the analysis of cerium element, it was confirmed that the oxidation proceeds gently as the batch advanced. For manganese, iron, and zinc, there was almost no difference between batches, which seemed to be stabilized by getting into the frame structure of the borosilicate glass. There were no elements that seemed to be clearly crystalline except for platinum group elements. Remarkable precipitation was hardly observed in zirconium and molybdenum with the imaging analysis.
Ambai, Hiromu; Nishizuka, Yusuke*; Sano, Yuichi; Uchida, Naoki; Iijima, Shizuka; Shiwaku, Hideaki; Yaita, Tsuyoshi
Journal of Nuclear Science and Technology, 56(2), p.193 - 200, 2019/02
During the accident that occurred at the Fukushima Daiichi Nuclear Power Plant, a large volume of seawater was introduced as coolant into the storage pools for spent nuclear fuel. If this fuel is reprocessed, some components of seawater will be mixed with the nitric acid solution containing metal ions in the reprocessing process where stainless steels are used as structural material. In this study, we investigated the effect of seawater components in high active liquid waste (HAW) containing nitric acid and metal ions as fission products on the corrosion behavior of SUS316L stainless steel. Corrosion tests were conducted in surrogate HAW containing artificial seawater (ASW). Intergranular corrosion was observed in the HAW with ASW, where Ru increased the corrosion potential to the transpassive region. An increase in the amount of ASW led to a decrease in the corrosion rate and suppression of intergranular corrosion. Interactions between Ru ions and seawater components, such as chloride ions, were indicated by the results of extended Xray absorption fine structure spectroscopy and cyclic voltammetry analyses of the solution containing ASW and HAW.
Kobayashi, Toru; Akutsu, Kazuhiro*; Nakase, Masahiko*; Suzuki, Shinichi; Shiwaku, Hideaki; Yaita, Tsuyoshi
Separation Science and Technology, 54(13), p.2077 - 2083, 2019/02
Development of separation reagent, which can efficiently separate lanthanides, is of increasing importance because it concerns establishment of purification and recycle techniques rare-earth elements. In our research group, several hetero donor type ligands, which have both oxygen and heterocyclic nitrogen atoms as donor atoms, were developed and revealed that this type of ligands show the selective complexation with specific lanthanide. In this paper, we will discuss the lanthaides complexation properties of the hetero donor type ligand containing benzimidazole group as nitrogen donor (-methyl--phenyl-2-(1-benzimidazol-2-yl)-pyridine-6-carboxamide) based on structural investigation by crystallography.
Okamoto, Yoshihiro; Nagai, Takayuki; Shiwaku, Hideaki
Yoyuen Oyobi Koon Kogaku, 62(1), p.11 - 17, 2019/01
The vitrified radioactive waste is a multicomponent material containing many kinds of elements. Synchrotron radiation XAFS with element selectivity is suitable for analysis of elements in the waste. From the XAFS analysis, the chemical state and the local structure of each element were clarified. Imaging XAFS technique was used as an analysis based on element distribution in the glass. The imaging XAFS is effective for analysis of elements that are less soluble in the glass like molybdenum and platinum group elements. It was clarified from the simultaneous imaging XAFS analyses of multiple elements that the chemical form of rhodium is strongly dominated by the distribution correlation with ruthenium. We proposed multi - scale structural analyses with wide angle scattering, PDF analysis, small angle scattering in order to evaluate the soundness of the vitrified waste.
Nagai, Takayuki; Okamoto, Yoshihiro; Shiwaku, Hideaki; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*; Hirono, Kazuya*; Homma, Masanobu*; Kobayashi, Hiromi*; Takahashi, Tomoe*; et al.
JAEA-Research 2018-007, 87 Pages, 2018/11
To select the chemical composition of a glass frit which can increase the waste content, the simulated waste glass samples prepared from a borosilicate glass frit including vanadium (V) were investigated by using Laser Ablation (LA) ICP-AES analysis, Raman spectrometry, and synchrotron XAFS measurement in this study on foundation business of the Agency for Natural Resources and Energy.
Kofuji, Hirohide; Watanabe, So; Takeuchi, Masayuki; Suzuki, Hideya; Matsumura, Tatsuro; Shiwaku, Hideaki; Yaita, Tsuyoshi
Progress in Nuclear Science and Technology (Internet), 5, p.61 - 65, 2018/11
Kobayashi, Toru; Suzuki, Shinichi; Shiwaku, Hideaki; Yaita, Tsuyoshi
Progress in Nuclear Science and Technology (Internet), 5, p.74 - 77, 2018/11
Development of extractant, which can efficiently separate actinides, is of increasing importance because it concerns establishment and simplification of separation techniques in nuclear fuel cycle and decontamination of radioactive wastes. In this study, the complexation properties of N-alkyl-N-phenyl-1,10-phenanthroline-2-carboxamide (PTA) with trivalent lanthanides (Ln) were investigated based on structural analysis by using X-ray crystallography and extended X-ray absorption fine structure (EXAFS) methods. As a result, it is revealed that two PTA molecules coordinate with Ln as tridentate ligand via two nitrogen in phenanthroline moiety and one oxygen in amide moiety in both crystal and solution states. The slight difference in coordination bond distances are observed between Eu and Nd complexes, this difference corresponds to the difference in ionic radius between Nd and Eu. This result indicates slight difference in ionic radii of Ln hardly affects coordination properties of PTA.
Nakase, Masahiko*; Kobayashi, Toru; Shiwaku, Hideaki; Kawamura, Takuya*; Takeshita, Kenji*; Yamamura, Tomoo*; Yaita, Tsuyoshi
Progress in Nuclear Science and Technology (Internet), 5, p.56 - 60, 2018/11
Gel/liquid extraction was investigated to achieve selective separation of trivalent actinides over lanthanides. In this study, thermosensitive hydrogel including N,N,N',N'-tetraallylpyridine-2,6-dicarboxamine (PDA) was synthesized, and its complexation with lanthanide was investigated by extended X-ray absorption fine structure experiments at SPring-8. The radial structure functions (RSF) of solution with gels with and without ligands at different temperatures showed slight differences. As the temperature increased, the RSF decreased owing to the increase in thermal vibration, but PDA-gel showed a shift in the first peak toward the shorter direction. This shift was attributed to the change in stoichiometry of PDA-Ln(III) complexes or coordination number of water molecules affected by the change of conformation of polymer chains and the hydrophilic/hydrophobic properties in the hydrogel.
Nagai, Takayuki; Kobayashi, Hidekazu; Shimamura, Keisuke; Oyama, Koichi; Sasage, Kenichi; Okamoto, Yoshihiro; Shiwaku, Hideaki; Yamanaka, Keisuke*; Ota, Toshiaki*
JAEA-Research 2018-005, 72 Pages, 2018/09
Addition of radioactive waste to a borosilicate glass frit affects the local structures of glass-forming elements and waste elements in a waste glass produced in a vitrification process. In this study, simulated waste glass samples were prepared from borosilicate glass frit including phosphorus pentaoxide, and we investigated local structures of sodium (Na), boron (B), and waste elements in these glass samples by using synchrotron XAFS measurements in soft and hard X ray region.
Okamoto, Yoshihiro; Nagai, Takayuki; Shiwaku, Hideaki
Hoshako, 31(4), p.274 - 280, 2018/07
As a method for disposal of nuclear waste, the use of vitrification technique is very promising. In this technique, many kinds of elements should be involved stably in the glass and chemical state of these elements in the glass must be confirmed in order to guarantee stability of the glass. We have used synchrotron based X-ray absorption fine structure (XAFS) technique, in which the element selectivity is utilized, to obtain the chemical state of each element in many kinds of simulated glass samples. In addition, imaging XAFS technique has been used to clarify correlation between constituent elements. We are going to contribute to research and development of the vitrification technique by using synchrotron radiation based XAFS analyses. In this article, we introduce results of the high energy XAFS of high temperature slag samples, the imaging study of high temperature borosilicate glass samples and the imaging XAFS analysis of platinum group metals in the borosilicate glass samples.
Suzuki, Tomoya*; Ogata, Takeshi*; Tanaka, Mikiya*; Kobayashi, Toru; Shiwaku, Hideaki; Yaita, Tsuyoshi; Narita, Hirokazu*
Metals, 8(7), p.558_1 - 558_10, 2018/07
The refining of platinum group metals is based mainly on solvent extraction methods, whereas Ru is selectively recovered by distillation as RuO. Replacement of distillation byextraction is expected to simplify the purification process. To develop an effective extraction system for Ru, we analyzed the Ru species in HCl with UV-Vis and EXAFS spectroscopies, and we examined the properties of Ru extracted with N-2-ethylhexyl-bis(N-di-2-ethylhexyl-ethylamide) amine (EHBAA). EXAFS and UV-Vis spectra of Ru in HCl solutions revealed that the predominant Ru species in 0.5-10 M HCl solutions changed from [RuCl(HO)] to [RuCl] with the HCl concentration. The extraction percentages of Ru in the EHBAA system increased with increasing HCl concentration, reached 80% at [HCl] = 5 M, and decreased athigher HCl concentrations. EXAFS analysis of the extracted complex indicated that the Ru had 5 Cl and 1 HO in its inner coordination sphere. The similarity of the dependence on HCl concentrations of the extraction in the EHBAA system and the distribution profile of [RuCl(HO)] on [RuCl(HO)] suggested that the EHBAA extracted the pentachlorido species.
Yoshigoe, Akitaka; Shiwaku, Hideaki; Kobayashi, Toru; Shimoyama, Iwao; Matsumura, Daiju; Tsuji, Takuya; Nishihata, Yasuo; Kogure, Toshihiro*; Okochi, Takuo*; Yasui, Akira*; et al.
Applied Physics Letters, 112(2), p.021603_1 - 021603_5, 2018/01
A synchrotron radiation photoemission electron microscope (SR-PEEM) was applied to demonstrate pinpoint analysis of micrometer-sized weathered biotite clay particles with artificially adsorbed cesium (Cs) atoms. Despite the insulating properties of the clay, we observed the spatial distributions of constituent elements (Si, Al, Cs, Mg, Fe) without charging issues. We found that Cs atoms were likely to be adsorbed evenly over the entire particle. Spatially-resolved X-ray absorption spectra (XAS) of the Cs M-edge region showed Cs to be present in a monocation state (Cs). Further pinpoint XAS measurements were also performed at the Fe L-edge to determine the chemical valence of the Fe atoms. Our results demonstrate the utility of SR-PEEM as a tool for spatially-resolved chemical analyses of various environmental substances, which is not limited by the poor conductivity of samples.
Okamoto, Yoshihiro; Nagai, Takayuki; Shiwaku, Hideaki; Inose, Takehiko*; Sato, Seiichi*
Nippon Genshiryoku Gakkai Wabun Rombunshi, 16(4), p.180 - 190, 2017/12
X-ray absorption fine structure (XAFS) and imaging XAFS analyses were performed to elucidate chemical state of rhodium in the simulated waste glass. The chemical forms of Rh in the glass were evaluated to be 84% RhO and 16% metal/alloy as the result of linear combination analysis of EXAFS data. According to the imaging XAFS analysis, the chemical form of Rh which was located together with Ru was mainly oxide (RhO). It suggests that stable (Ru,Rh)O solid solution exists in the simulated glass. On the other hand, that of Rh of which distribution did not accord with Ru in the glass was mainly metallic. In the case of metallic Rh in the glass, it tended to become an aggregation form. It can be concluded that the chemical state of Rh was much affected by the existence and distribution of Ru element.
Narita, Hirokazu*; Maeda, Motoki*; Tokoro, Chiharu*; Suzuki, Tomoya*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi
Analytical Sciences, 33(11), p.1305 - 1309, 2017/11
Sasaki, Yuji; Morita, Keisuke; Ito, Keisuke; Suzuki, Shinichi; Shiwaku, Hideaki; Takahashi, Yuya*; Kaneko, Masaaki*; Omori, Takashi*; Asano, Kazuhito*
Proceedings of International Nuclear Fuel Cycle Conference (GLOBAL 2017) (USB Flash Drive), 4 Pages, 2017/09
no abstracts in English
Watanabe, So; Sano, Yuichi; Shiwaku, Hideaki; Yaita, Tsuyoshi; Ono, Shimpei*; Arai, Tsuyoshi*; Matsuura, Haruaki*; Koka, Masashi*; Sato, Takahiro*
Nuclear Instruments and Methods in Physics Research B, 404, p.202 - 206, 2017/08
Nagai, Takayuki; Kobayashi, Hidekazu; Sasage, Kenichi; Ayame, Yasuo; Okamoto, Yoshihiro; Shiwaku, Hideaki; Yamanaka, Keisuke*; Ota, Toshiaki*
JAEA-Research 2017-005, 54 Pages, 2017/06
Addition of radioactive waste to a borosilicate frit affects the local structures of boron (B) and waste elements in a waste glass. Synchrotron XAFS measurement was applied to investigate the local structural changes by using simulated waste borosilicate glass samples. Following results were obtained by the B K-edge XAFS analysis. It was confirmed that B K-edge XAFS analysis enables us to discriminate sp type boron (BO) from sp type boron (BO). Addition of waste elements to a glass frit increases the percentage of BO and decreases that of BO. By decreasing the SiO/AlO ratio or increasing the (SiO+BO)/AlO ratio in the glass composition, the BO percentage increases and the BO percentage decreases. Addition of PO decreases the BO percentage and increases the BO percentage. Following results were obtained from XAFS measurement of the waste elements. Cerium (Ce) valence is more reduced with the increase of the BO content. Addition of PO has a tendency to reduce the Ce valence and to enhance deposition of Zr oxide. Deposition of ruthenium compounds separated from glass phase can not be improved by changing the BO content. This study was performed as a part of the project, "Improvement of vitrification process of high-level radioactive liquid wastes" on the foundation business of the Agency for Natural Resources and Energy.