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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.
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.
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.
Tomita, Ryohei; Tomita, Jumpei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka
Hosha Kagaku, (48), p.1 - 15, 2023/09
Secondary Ion Mass Spectrometry (SIMS) is the method to detect secondary ions produced by the sputtering of primary ions. SIMS is one of effective method to measure isotopic composition of particles containing nuclear material in environmental sample for safeguards. We are a group member of the International Atomic Energy Agency (IAEA)'s network of analytical laboratories and have developed analytical techniques using SIMS and other mass spectrometers for nuclear safeguards. We will introduce the principle of SIMS and analytical techniques developed by our group to measure isotopic composition of uranium particles which having a particle diameter of micron order in environmental sample for safeguards.
Yamaguchi, Akiko
Hosha Kagaku, (48), p.56 - 59, 2023/09
The adsorption reaction on clay minerals is an important chemical reaction that controls the environmental behaviors of various ions at the Earth's surface, but the details are unknown due to the complexity of the reaction, such as the diversity of clay mineral compositions and the existence of multiple adsorption sites. In this study, we focused on the adsorption structure on clay minerals at the atomic level, and clarified it in detail by combining X-ray absorption fine structure (XAFS) methods and first-principles calculations. In particular, XAFS measurements of radium, which has the largest ionic radius among alkaline earth metals and has been difficult to measure at the atomic level, were successfully performed, and new knowledge was obtained by comparing the results with those of other elements.
Kumagai, Yuta
Hoshasen Kagaku (Internet), (115), p.43 - 49, 2023/04
Oxidation and dissolution of uranium oxide materials has been a subject of numerous studies as a basis of the geological disposal technology for spent nuclear fuel. The understandings obtained by these studies provide useful suggestions for research and development regarding the retrieval and storage of nuclear fuel debris generated by a nuclear severe accident. Here, these research backgrounds of oxidative dissolution of uranium oxides are briefly reviewed and some studies relating to radiation-induced reactions will be introduced.
Sr and 
Cs into wild animals after the Fukushima Daiichi Nuclear Power Plant accident using hard tissue as an indicatorKoarai, Kazuma
Hosha Kagaku, (47), p.24 - 27, 2023/03
Ca-based tissues, such as teeth and bones, are called hard tissues. Sr is incorporated into the tooth during calcification. Once incorporated, it remains until the tooth falls out. Therefore, Sr in teeth recorded Sr contamination by the 1F accident in the environment during the formation period. The article presents current research findings.
Tokunaga, Kohei
Hosha Kagaku, (47), p.20 - 23, 2023/03
no abstracts in English
Yamaguchi, Akiko
Hosha Kagaku, (47), p.41 - 42, 2023/03
Radium (Ra) is essential for various fields, such as environmental chemistry and nuclear medicine. However, even the hydration structure of Ra remains unclear due to the difficulty in the Ra treatment, caused by the fact that Ra has no stable isotopes and forms radon, noble gas. This study measured the extended X-ray absorption fine structure (EXAFS) of Ra to investigate its hydration structure and adsorption structures on clay minerals. The EXAFS results were consistent with our environmental analysis of core samples in a uranium mine.
Maekawa, Fujio
Ryoshi Bimu Kagaku No Kiso To Oyo; NSA/Commentaries, No.27, p.15 - 25, 2023/03
The nuclear transmutation technology that is one of the most beneficial industrial applications of quantum beams to humankind is explained.
Cs concentration and Cs/Cs isotopic ratio measurementShimada, Asako
Bunseki Kagaku, 71(12), p.625 - 633, 2022/12
Cesium-135 is one of the important nuclides to assess the safe disposal of High Level Waste (HLW). Therefore, the calculation code and library to evaluate the Cs concentration in HLW have been improved through comparisons with experimental results. On the other hand, even basic data of Cs, such as its half-life, have large uncertainty. Because the Cs/Cs isotopic ratio suggests its origin and introduction date, the ratios in environmental samples are measured to study global fallout from nuclear weapons testing and nuclear accidents. Such measurement methods was attracted attention, in particular, after the accident at the Fukushima Daiichi Nuclear Power Station. Measurement of the Cs/Cs isotopic ratio in environmental samples was challenging because the radiocesium has a very low concentration and it co-exists with huge amounts of Ba isotopes, which are isobaric interfering nuclides, are co-exist. Chemical separation methods were developed to eliminate interfering nuclides and improve the performance of the mass spectrometer to enable the measurement of the ratios. In this review, the features of the Cs/Cs isotopic ratio for each origin and recent developments in measurement techniques are summarized.
Takeda, Shiho
Joho No Kagaku to Gijutsu, 72(10), P. 404, 2022/10
This paper is a book review of "Intellectual Freedom Manual (Tenth edition, 2021)" (compiled by Office for Intellectual Freedom of the American Library Association, and translated by Yoshitaka Kawasaki, et al). Summary as well as key points of the book is described.
Murata, Ryutaro
Joho No Kagaku to Gijutsu, 72(9), P. 362, 2022/09
This paper is a book review of "Timeline of the Library in Contemporary Japan 1945-2020" and introduced the outline and features of the book with my opinion.
-process and stellar evolutionIwamoto, Nobuyuki
Kagaku, 92(9), p.835 - 839, 2022/09
no abstracts in English
Kitamura, Akihisa*; Okazaki, Sota*; Kondo, Mitsuru*; Watanabe, Takahiro; Nakanishi, Toshimichi*; Hori, Rie*; Ikeda, Masayuki*; Ichimura, Koji; Nakagawa, Yuki; Mori, Hideki*
Shizuoka Daigaku Chikyu Kagaku Kenkyu Hokoku, (49), p.73 - 86, 2022/07
On July 3 2021, a debris flow caused by a landslide from a landfill occurred along the Aizome River in the Izusan area of Atami City, Shizuoka. In this study, debris flow deposits and soil samples were characterized in terms of their sedimentology and geochemically analyzed.
O-induced oxidative degradation of simulated fuel debrisKumagai, Yuta; Kusaka, Ryoji; Nakada, Masami; Watanabe, Masayuki; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Sasaki, Takayuki*
Hoshasen Kagaku (Internet), (113), p.61 - 64, 2022/04
The severe accident at TEPCO's Fukushima Daiichi Nuclear Power Station resulted in generation of fuel debris. The fuel debris is in contact with water and the radiolysis of water can accelerate degradation of the debris. The analysis of particles sampled from inside or near the damaged reactors indicates the complicated compositions of the fuel debris. It is challenging to estimate the effect of water radiolysis on such a complicated material. Therefore, in this study, we investigated the potential degradation process by leaching experiments of simulated fuel debris in aqueous HO solution. The results show that the reaction of HO induced uranium dissolution from most of the samples and then formation of uranyl peroxides. In contrast, a sample that had U-Zr oxide solid solution as the major phase exhibited remarkable resistance to HO. These findings revealed that the degradation of the simulated debris reflects the reactivity and stability of the uranium phase in the matrices.
Yamaguchi, Akiko; Nagata, Kojiro*; Tanaka, Kazuya; Kobayashi, Keita; Kobayashi, Toru; Shimojo, Kojiro; Tanida, Hajime; Sekiguchi, Tetsuhiro; Kaneta, Yui; Matsuda, Shohei; et al.
Hosha Kagaku, (45), p.28 - 30, 2022/03
no abstracts in English
