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Yomogida, Takumi; Takahashi, Yoshio*
Chikyu Kagaku, 59(1), p.1 - 10, 2025/03
X-ray absorption fine structure XAFS spectroscopy techniques, which are applicable to almost all elements, provide information on elemental valence and local structure with high elemental selectivity and high sensitivity. It has become an indispensable method in space geochemistry and environmental chemistry. This review presents examples of the application of fluorescence XAFS methods to elements that are difficult to detect by conventional methods, and examples where new chemical species information has been obtained by increasing the energy resolution of the X-ray fluorescence (XRF) detection system to obtain XAFS.
ssbauer spectroscopyMorii, Shiori
Hosha Kagaku, (51), p.21 - 23, 2025/03
To understand the influence of redox properties of structural Fe in clay minerals on removal and immobilization of radionuclides in geological disposal environment, we investigated redox and structural properties of Fe in clay minerals at reducing conditions. Clay mineral sample was reduced by controlled-potential electrolysis at -0.5 V vs the standard hydrogen electrode. Redox state and structural properties of Fe in this prepared clay mineral sample was investigated by Fe-57 Mssbauer spectroscopy. From the Mssbauer spectra, we found that structural Fe(III) in octahedral sheets was reduced to Fe(II). This fundamental information about the Fe in clay minerals will contribute to technical reliabilities of geological disposal.
Aoki, Katsutoshi*; Machida, Akihiko*; Saito, Hiroyuki*; Hattori, Takanori
Koatsuryoku No Kagaku To Gijutsu, 35(1), p.4 - 11, 2025/03
Iron reacts with hydrogen to form solid solutions with body-centered cubic, face-centered cubic, hexagonal close packed, and double hexagonal close packed structures at high temperatures and high pressures. Neutron diffraction is the most powerful tool for determining the occupation sites and occupancies of hydrogen atoms dissolved in a metal lattice. Structural parameters, including hydrogen occupation sites and occupancies, are refined via Rietveld analysis for neutron diffraction data. We present our expertise in Rietveld refinement of iron hydrides accumulated over 10 years.
Hirota, Noriaki; Nakano, Hiroko; Takeda, Ryoma; Ide, Hiroshi; Tsuchiya, Kunihiko; Kobayashi, Yoshinao*
Zairyo No Kagaku To Kogaku, 61(6), p.248 - 252, 2024/12
A comparative analysis of the 0.2 % yield stress in SUS304L stainless steel revealed that lower strain rates and higher temperatures significantly reduce yield stress. Grain refinement from 68.6 
m to 0.59 m minimally impacted the rate of yield stress reduction at slower strain rates. However, finer grains showed a decrease in yield stress at reactor operating temperature compared to room temperature. In slow strain rate tests under conditions promoting intragranular stress corrosion cracking (SCC), SUS304L with grain sizes of 28.4 m or smaller exhibited similar fracture strains comparable to those at reactor operating temperatures, whereas coarse-grained SUS304L showed reduced fracture strain. Microstructural analysis showed that in smaller grains, over 87 % of the fracture surface was ductile. In particular, SUS304L with 0.59 m grains exhibited a higher presence of {111} / 
3 boundaries, which decreased with grain growth. These results indicate that grain refinement will suppress intragranular SCC by slowing corrosion progression through increased {111} / 3 boundaries.
Asai, Shiho*; Horita, Takuma
Bunseki Kagaku, 73(10-11), p.569 - 578, 2024/10
The accurate estimation of the quantities and composition of long-lived radionuclides in radioactive waste is crucial for assessing the long-term safety of its disposal. Traditionally, theoretical predictions of the quantities of long-lived radionuclides obtained from burn-up calculation codes with evaluated nuclear data have been used especially for the safety assessment of high-level radioactive waste. However, such nuclear data used in theoretical predictions have not been sufficiently validated due to the scarcity of the reported measurement data. In this study, we aim to contribute to the improvement of the reliability of theoretical predictions by confirming them with the measured quantities of long-lived radionuclides per unit mass of uranium in spent nuclear fuel, which are output data obtained from the burnup calculation code. This involves measuring the long-lived radionuclides present in nuclear fuel pellets used in commercial nuclear reactors. Specifically, we focused on 
Zr, 
Pd, and 
Cs, which can be effectively measured using an inductively coupled plasma mass spectrometer (ICP-MS). Besides the purpose of validating the nuclear data, this article also highlights viable measurement techniques for these radionuclides, along with examples demonstrating their applicability to long-lived radionuclides, including the preparation procedures for their measurement.
Yanagisawa, Kayo; Yokota, Hiromi*; Fujimoto, Katsushige*; Takagai, Yoshitaka*
Bunseki Kagaku, 73(9), p.515 - 522, 2024/09
On-line isotope dilution-laser ablation-inductively coupled plasma-mass spectrometry (on-line ID-LA-ICP-MS) is capable of quantification for each point ablated by laser, then the quantitative mapping of elements can be also conducted by reconstruction of the obtained each point data. The volume of data obtained as flow peaks in this system as a flow injection analysis, will be multiplied by each data such as number of m/z, scan time, time resolution and measurement position, and the total amount of data is enormous, resulting in a large human power and time consumption for data processing. In this paper, an original application software using Python to improve the efficiency of data processing in on-line ID-LA-ICP-MS was developed. To discriminate between the time-to-peak intensity and the background noise, an automatic peak detection using penalized asymmetric least squares was developed.
Osawa, Takahito
Chikyu Kagaku, 58(3), p.70 - 82, 2024/09
This paper describes the recent research and development status of neutron-induced prompt gamma-ray analysis and muonic X-ray analysis as elemental analysis methods using quantum beams. Neutron-induced prompt gamma-ray analysis is an elemental analysis method using neutrons, and is often used as a nondestructive quantitative analysis method for boron and hydrogen. The prompt gamma-ray analysis system (PGA) installed at JRR-3 is an old device constructed more than 30 years ago, but recently an articulated robot has been installed and an advanced automated analysis system is in operation. On the other hand, the muonic X-ray analysis method is attracting attention as a new analysis method, and can detect light elements such as oxygen nondestructively. Both analytical methods have been used in the analysis of the samples of asteroid Ryugu, and will continue to evolve greatly as analytical methods in the future.
Matsueda, Makoto
Hosha Kagaku, (50), p.55 - 57, 2024/09
Concentrations and isotope ratios of 
Tc, 
I, and Pu isotopes, which are long-lived nuclides, provide us the important information in many fields such as the decommissioning of nuclear facilities and investigation of environmental dynamics. It will increase the effort for their analysis in the future. Therefore, their analytical methods should be developed for corresponding many samples, and inductively coupled plasma mass spectrometry (ICP-MS) is expected to be a technique to help resolve them. However, there are some problems in the analysis of these nuclides, and technological innovations have not progressed yet. In this paper, we attempted to solve these problems by combining multiple separation systems with ICP-MS.
S
under pressureKosaka, Yusuke*; Oishi, Kazuki*; Hattori, Takanori
Koatsuryoku No Kagaku To Gijutsu, 34(3), p.121 - 126, 2024/09
Transition-metal intercalated dichalcogenides have attracted attention due to the observation of chiral helimagnetism (CHM) and chiral soliton lattice in CrNbS. It forms a chiral monoaxial crystal structure with a space group P622. To examine the pressure effect on the CHM period of CrNbS, we performed small-angle neutron scattering experiments with a piston-cylinder pressure cell up to 1.2 GPa. We observed a decrease in the magnetic transition temperature with increasing pressure. Moreover, the CHM period decreased with increasing pressure. Compared to the decrease of the lattice constant, that of the CHM period is much larger. This indicates that applying pressure weakens the amplitude of Dzyaloshinskii-Moriya interaction.
Machida, Shinichi*; Hattori, Takanori; Nakano, Satoshi*; Sano, Asami; Funakoshi, Kenichi*; Abe, Jun*
Koatsuryoku No Kagaku To Gijutsu, 34(3), p.134 - 142, 2024/09
A diamond anvil cell (DAC) for high-pressure neutron diffraction experiments has been developed at the PLANET beamline, Materials and Life Science Experimental Facility, in J-PARC. The conically supported diamond anvils were used for high-pressure generation. We succeeded in obtaining the neutron data for D
O ice up to 69.4 GPa. In addition, the gasket materials suitable for the neutron diffraction measurements were investigated. 11 kinds of alloys were tested and SUS304, Inconel718 and M2052 (73Mn-20Cu-5Ni-2Fe, at%) alloys showed excellent performance. Especially, M2052 null-matrix alloy has proven to be useful for neutron diffraction experiments where the beam inevitably hits the gasket. We then obtained refinable neutron diffraction profiles in Rietveld analysis from DO ice at least up to 43.3 GPa.
Nankawa, Takuya
Kagaku, 79(8), p.48 - 52, 2024/08
Lacquer is a natural paint with excellent water and chemical resistance. It has long been known that adding a very small amount of iron into raw lacquer produces a very beautiful black color called Shikoku. However, the structure and reactions of lacquer are still largely unknown, and the reason of black color is also unclear. In this study, we analyzed the structure of raw lacquer and black lacquer films by using different kind of quantum beams. As a result, black lacquer has a completely different nanostructure from raw lacquer, and that the color changes depending on the difference in the structure. This result is the first successful analysis of the structure of the lacquer film, which had been a mystery for many years. This commentary describes this research and also explains how this research has been proceeded.
Noguchi, Hiroki; Sato, Hiroyuki; Nishihara, Tetsuo; Sakaba, Nariaki
Kagaku Kogaku, 88(5), p.211 - 214, 2024/05
High temperature gas-cooled reactor (HTGR), one of the next-generation innovative reactors, has an inherent safety and can generate very high-temperature heat which can be used for various heat application including hydrogen production. In Japan, Green Growth Strategy for Carbon Neutrality in 2050 and Basic Policy for the Realization of GX state the promotion of technology development necessary for mass and low-cost carbon-free hydrogen production and development and construction of next-generation innovative reactors including the HTGR for the decarbonization of industrial sectors. Based on these policies, JAEA has been conducted the world's first hydrogen production test using nuclear heat from an HTGR, in addition to verifying the excellent safety features of HTGR, and has also started to study the construction of an HTGR demonstration reactor in cooperation with the industrial community. This paper shows the current status of R&D of HTGR in Japan.
Ikeda, Atsushi
Bunseki Kagaku, 73(4.5), p.147 - 159, 2024/04
Factor analysis (FA), one of the multivariate analysis methods that are frequently employed in chemometrics, is a powerful tool to extract physical/chemical information of pure components from the analytical data of the mixture of the components. Although FA has been applied mainly to the quantitative analysis in the field of analytical chemistry, its application to the qualitative analysis has been limited. This article aims at introducing FA to the qualitative analysis for determining the speciation/structure of individual chemical species/compounds by X-ray absorption spectroscopy (XAS). The fundamental concept to extract physically/chemically meaningful information from XAS-FA is described, and some reported studies using XAS-FA for the qualitative determination of chemical species/compounds are summarized.
Ouchi, Kazuki
Hosha Kagaku, (49), p.3 - 7, 2024/03
I introduce the elucidation of the deposition following the oxidation state of uranium and the electrochemical behavior of uranium(IV) chloride in an ionic liquid-organic mixture, as a basic study of in-solution reactions. In addition, I introduce the development of separation methods for actinides using a microchemical chip and polyacrylamide gel electrophoresis, as an applied study for quantitative analytical methods for small amounts of samples.
Maeda, Shigetaka
Hoshasen Kagaku Furonteia, (5), P. 17, 2024/02
Regarding Actinium-225, which is one of the medical radioisotopes and has been attracting attention today, we will report on the domestic movement toward domestic production, the research and development plan and progress for production of Actinium-225 using the experimental fast reactor Joyo.
Morii, Shiori; Yomogida, Takumi; Asai, Shiho*; Ouchi, Kazuki; Oka, Toshitaka; Kitatsuji, Yoshihiro
Bunseki Kagaku, 72(10.11), p.441 - 448, 2023/10
Rapid analytical method for the determination of Zr-93 in radioactive wastes has been developed. Laser ablation (LA)-ICP-MS was applied to the analysis of Zr isotopes in simulated high-level radioactive waste (HLW). Sample preparation time was dramatically reduced by using a DGA resin as the adsorbent for Zr. Direct quantification of Zr isotopes in this resin sample was carried out by LA-ICP-MS. Laser settings were optimized to obtain a reliable isotope ratio of the sample by LA-ICP-MS. Quantification of Zr isotopes in the simulated HLW solution by isotope dilution mass spectrometry (IDMS) was examined. The amount of Zr-90 in the sample obtained by IDMS corresponded to a value calculated from the given concentration of Zr in the sample within uncertainty. Thus, this method can be applied for the quantification of Zr-93 in radioactive wastes.
Nitta, Ayako
Kagaku To Kyoiku, 71(10), p.424 - 427, 2023/10
no abstracts in English
Tachi, Yukio
Kagaku To Kyoiku, 71(10), p.420 - 423, 2023/10
no abstracts in English
Arai, Taiki*; Yoshigoe, Akitaka; Motohashi, Mitsuya*
Zairyo No Kagaku To Kogaku, 60(5), p.153 - 158, 2023/10
Si oxide films are currently widely used as insulating materials in electronic devices and biomaterials. The atomic bonding state of these films significantly influences the properties of each device, thus it is particularly necessary to understand and control the chemical bonding state between Si and O in the films. In this study, the Si oxide films formed by anodic oxidation on Si substrate surfaces in extremely low concentrations of HF solutions were analyzed by X-ray photoelectron spectroscopy mainly focusing on Si2p and F1s spectra. Although the HF concentration is in the order of ppm, the films contain percent order of F atoms, suggesting the formation of Si-F and Si-O-F bonds in the films. It was also found that the different depth profiles for F and O atoms was observed, indicating that the surface reaction processes seem to be different depending on each element.
