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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.
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.
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
Matsuya, Yusuke; Kai, Takeshi; Ogawa, Tatsuhiko; Hirata, Yuho; Sato, Tatsuhiko
Hoshasen Kagaku (Internet), (112), p.15 - 20, 2021/11
Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo code enabling radiation kinetics, which is often used in diverse research fields, such as atomic energy, engineering, medicine and science. After released in 2010, the PHITS code has been developed to expand its functions and to improve its convenience. In the few years, track-structure mode has been introduced in PHITS that can simulate each atomic interaction by electrons, positions, protons and carbon ions in liquid water. Thanks to the development of track-structure mode, the latest PHITS code enables microscopic dose calculations by decomposing it to the scale of DNA. Aiming at realizing the track-structure mode with high precision, the further developments of electron and ion track-structure mode for arbitrary materials are recently ongoing. This review shows the development history and future prospect of PHITS track-structure mode, which can expect to be further applied to the research fields of atomic physics, radiation chemistry, and quantum life science.
Miyazaki, Yasunori; Sano, Yuichi
Hoshasen Kagaku (Internet), (112), p.27 - 32, 2021/11
no abstracts in English
Oka, Toshitaka; Takahashi, Atsushi*
Hoshasen Kagaku (Internet), (110), p.13 - 19, 2020/10
The article depicts how to estimate the external exposure dose for wild animals using electron spin resonance (ESR) spectroscopy. The relationship between the CO radical intensity and the absorbed dose, that is, dose response curve of tooth enamel of Japanese macaque was observed, and the detection limit of our method was estimated. The estimated detection limit of 33.5 mGy is comparable to the previously reported detection limit for human molar teeth. The external exposure dose for seven wild Japanese macaques captured in Fukushima prefecture were examined using this dose response curve. The estimated external exposure dose were ranged between 45 mGy to 300 mGy.
Tanaka, Kiriha*; Muto, Jun*; Nagahama, Hiroyuki*; Oka, Toshitaka
Hoshasen Kagaku (Internet), (110), p.21 - 30, 2020/10
In a fault dating by electron spin resonance (ESR), the number of unpaired electrons trapped in defects in minerals contained in a fault material is detected as ESR intensity. Based on the quantitative change of the intensity before and after an earthquake, the last age of a fault movement can be estimated. However, this method has a hypothesis called "zero-setting" which assumes the decrease in the ESR intensity to zero by fault movement during an earthquake. In order to understand and demonstrate zero-setting, the analysis of the natural fault materials and experiments mimicking fault movements have been conducted. In this paper, we summarized the previous studies about zero-setting by fault movement and described the current status and challenges.
Kusaka, Ryoji
Hosha Kagaku, (41), p.31 - 33, 2020/03
This commentary article introduced researches involved in encouragement award 2019 of the Japan Society of Nuclear and Radiochemical Sciences. Vibrational sum frequency generation (VSFG) spectroscopy and interfacial studies of solvent extraction of lanthanides and actinides using VSFG spectroscopy were described.
Ogawa, Tatsuhiko; Sato, Tatsuhiko; Yamaki, Tetsuya*
Hoshasen Kagaku (Internet), (108), p.11 - 17, 2019/11
Scintillators are generally used to detect various kinds of particles such as electrons, gammas, protons and heavy ions. Scintillators emit photons according to the energy deposited to the crystal. It is also known that light yield is suppressed for particles depositing energy densely owing to quenching. Moreover, it is suggested that quenching is attributed to transfer of energy from excited fluorescent molecules to damaged molecules (F
rster mechanism or Dexter mechanism). In this study, energy deposition in a scintillator crystal by radiation was calculated using radiation transport codes to finally obtain excitation and damage of fluorescent molecules. Based on the calculation, spatial configuration of exited and damaged molecules. Then the probability that Frster mechanism takes place in excited molecules were estimated to obtain the number of fluorescent molecules that emit photons. As a result, light yield is proportionally increased with increase in the incident energy in case of electron incidence. On the other hand, light yield is increased non-linearly in case of proton incidence. This trend is in a good agreement with the experimental results.
Koarai, Kazuma
Hosha Kagaku, (40), p.26 - 27, 2019/09
Report about "The 20th Workshop on Environmental Radioactivity" was submitted in 
. There were 195 participants in the workshop. They actively discussed environmental radioactivity and pollution after the Fukushima-Daiichi Nuclear Power Plant. Presentation awards were given to 4 persons.
Sr and Cs in hard tissues of cattle and monkey in the Fukushima environmentKoarai, Kazuma
Hosha Kagaku, (40), p.34 - 36, 2019/09
Abstract of doctor thesis was submitted to "Hoshakagaku", which is Japanese article. I described main theme of the thesis. The hard tissues of the animals incorporated at the development stage and bone methabolism of the tissues. On the other hand, Cs was incorporated not only the development stage but also after the stage. Strontium-90 and cesium-137 in the cattle teeth reflected the pollution after the Fukushima-Daiichi Nuclear Power Plant accident. The thesis showed and Cs in the hard tissues would an important indicator of the environmental pollution.
O concentration on oxidative dissolution of UOKumagai, Yuta
Hoshasen Kagaku (Internet), (107), p.77 - 78, 2019/04
Reaction of hydrogen peroxide (HO) with uranium dioxide (UO) oxidizes U(IV) to water-soluble U(VI). In the concept of direct geological disposal of spent nuclear fuel, this reaction is expected to induce dissolution of UO matrix of the spent fuel. This study investigate effect of HO concentration on the kinetics and the yield of U(VI) dissolution of this reaction. A series of experiments of the reaction of HO with UO powder dispersed in water has been carried out. The experimental results reveal that increase in the HO concentration slows down the reaction and decreases the yield of U(VI) dissolution. This observation suggests that a reaction intermediate is generated in the course of the HO reaction on the surface of UO.
Kai, Takeshi; Yokoya, Akinari*; Fujii, Kentaro*; Watanabe, Ritsuko*
Hoshasen Kagaku (Internet), (106), p.21 - 29, 2018/11
It is thought to that the biological effects such as cell death or mutation are induced by complex DNA damage which are formed by several damage sites within a few nm. As the prediction of complex DNA damage at an electron track end, we report our outcomes. These results indicate that DNA damage sites comprising multiple nucleobase lesions with a single strand breaks can be formed by multiple collisions of the electrons within 1 nm. This multiple damage site cannot be processed by base excision repair enzymes. Pre-hydrated electrons can also be produced resulting in an additional base lesion over a few nm from the multi-damage site. This clustered damage site may be finally converted into a double strand break. These DSBs include another base lesion(s) at their termini that escape from the base excision process and which may result in biological effect. Our simulation is useful to reveal phenomena involved in radiation physico-chemistry as well as the DNA damage prediction.
Shimada, Asako
Hosha Kagaku, (38), p.30 - 31, 2018/09
no abstracts in English
