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Journal Articles

The Chemistry of uranium (II); Method and practice

Sato, Nobuaki*; Kirishima, Akira*; Watanabe, Masayuki; Sasaki, Takayuki*; Uehara, Akihiro*; Takeda, Shino*

Uran No Kagaku (II); Hoho To Jissen, 143 Pages, 2021/03

This book describes necessary facts when readers would have an opportunity to treat Uranium for experiments. In the content, the method section shows experimental facilities and equipment including method, and the practical section mentions solution and solid state experiments using Uranium and/or radioisotopes.

Journal Articles

Improvement of adsorption performances of Sr adsorption fiber and investigation for realizing simple $$^{90}$$Sr analysis

Horita, Takuma; Asai, Shiho*; Konda, Miki; Matsueda, Makoto; Hanzawa, Yukiko; Kitatsuji, Yoshihiro

Bunseki Kagaku, 69(10/11), p.619 - 626, 2020/10

 Times Cited Count:0 Percentile:100(Chemistry, Analytical)

We have developed a Sr adsorption fiber for rapid analysis of $$^{90}$$Sr. The prepared Sr adsorption fiber has a Sr-extraction layer that densely retains a Sr-selective extractant, an 18-crown-6 ether derivative, on the fiber surface. Hydrophobic group-containing polymer chains embedded onto the surface of the fiber allow to form a hydrophobic phase, incorporating Sr-selective extractants. This unique surface structure provides high adsorption capacity, leading to rapid and highly efficient adsorption of Sr$$^{2+}$$. The adsorption capacity of the Sr adsorption fiber was 3 times higher than commercially available 18-crown-6 ether derivative-impregnated resin (Sr Resin). The equilibrium adsorption capacity of the Sr adsorption fiber was comparable to the Sr Resin. The retained $$^{90}$$Sr was finally determined by a GM counter. The total analysis time including the Sr adsorption and measurement was about 1 hour.

Journal Articles

External dose estimation for wild animals using ESR spectroscopy

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$$_{2}$$ 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.

Journal Articles

A Fault dating method using an electron spin resonance

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.

Journal Articles

Spontaneous debonding behaviour of reinforcement fine particles in aluminium; Toward high-strength metallic materials development

Toda, Hiroyuki*; Tsuru, Tomohito; Yamaguchi, Masatake; Matsuda, Kenji*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*

Kagaku, 75(10), p.48 - 53, 2020/10

Highly-concentrated precipitations play therefore dominant role in mechanical properties and hydrogen embrittlement of aluminum alloys. It has been considered that the coherent interface between matrix and precipitation does not contribute to the crack initiation and embrittlement due to its coherency. Here, we discovered the origin of unprecedented quasi-cleavage fracture mode. Hydrogen partitioning at various defect sites is investigated comprehensively combined with experiment, theory and first-principles calculations. We demonstrate that despite low excess free volume, the aluminum-precipitation interface is more preferable trap site than void and grain boundary. The cohesivity of the interface deteriorates significantly with increasing occupancy while hydrogen atoms are trapped stably up to extremely high occupancy equivalent to spontaneous cleavage.

Journal Articles

The Chemistry of uranium (I); Basics and application

Sato, Nobuaki*; Kirishima, Akira*; Watanabe, Masayuki

Uran No Kagaku (I); Kiso To Oyo, 184 Pages, 2020/06

This particular book deals with fundamental items related with chemistry of Uranium and consists of basic section and practical section. In the basic section, inorganic and radiochemistry of Uranium was described. On the other hand, in the practical section, the process chemistry related with reprocessing of nuclear fuels and "debris" involved with Fukushima Daiichi Power Plant accident were described. This book is intended for use by scientists, engineers and students in the nuclear industry in their education and/or professional practice.

Journal Articles

Development of lanthanide and actinide studies toward interface chemistry using vibrational sum frequency generation spectroscopy

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.

Journal Articles

Prediction of scintillation light yield based on track-structure simulation

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$"{o}$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 F$"{o}$rster 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.

Journal Articles

First ionization potentials of Fm, Md, No and Lr; Verification of filling-up of 5f electrons and confirmation of the actinide series

Sato, Tetsuya

Kagaku To Kogyo, 72(10), P. 867, 2019/10

We conducted measurements of the first ionization potential (IP$$_1$$) of the heavy actinide elements, lawrencium (Lr, $$Z = 103$$), nobelium (No, $$Z = 102$$), mendelevium (Md, $$Z = 101$$) and fermium (Fm, $$Z = 100$$) by using a novel method based on a surface ionization process. The IP$$_1$$ measurements have been performed using the ISOL (Isotope Separator On-Line) system equipped with a surface ion-source with short-lived heavy actinide isotopes, $$^{256}$$Lr ($$T_{1/2}$$ = 27s), $$^{257}$$No ($$T_{1/2}$$ = 24.5s), $$^{251}$$Md ($$T_{1/2}$$ = 4.27 min), and $$^{249}$$Fm ($$T_{1/2}$$ = 2.6 min). Our experimental results clearly showed that the IP$$_1$$ of Lr is distinctly low among actinide elements. Moreover, No has the highest IP$$_1$$ among them due to its full-filled 5f and 7s orbitals; the IP$$_1$$ value increased with an atomic number up to No and decreased dramatically at Lr, indicating the similar trend with that of heavy lanthanide elements. Therefore, we concluded Lr would be the last member of the actinide series.

Journal Articles

Study on irradiation hardening mechanism of RPV steel; Experiments for irradiation temperature control

Ha, Yoosung; Shimodaira, Masaki; Tobita, Toru; Hanawa, Satoshi; Yamasaki, Shota*; Uno, Sadanori*

2018-Nendo Ryoshi Kagaku Gijutsu Kenkyu Kaihatsu Kiko Shisetu Kyoyo Jisshi Hokokusho (Internet), 3 Pages, 2019/09

no abstracts in English

Journal Articles

Nuclear properties of superheavy elements

Koura, Hiroyuki

Chojugenso Kagaku No Saizensen; Furonteia Shirizu, 2, p.49 - 58, 2019/09

no abstracts in English

Journal Articles

The 20th Workshop on Environmental Radioactivity

Koarai, Kazuma

Hosha Kagaku, (40), p.26 - 27, 2019/09

Report about "The 20th Workshop on Environmental Radioactivity" was submitted in ${it hoshakagaku}$. 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.

Journal Articles

Studies on incorporation of $$^{90}$$Sr and $$^{137}$$Cs in hard tissues of cattle and monkey in the Fukushima environment

Koarai, 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 $$^{90}$$ at the development stage and bone methabolism of the tissues. On the other hand, $$^{137}$$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 $$^{90}$$ and $$^{137}$$Cs in the hard tissues would an important indicator of the environmental pollution.

Journal Articles

Total-reflection high-energy positron diffraction (TRHEPD)

Fukaya, Yuki

Yodenshi Kagaku, (13), p.3 - 10, 2019/09

no abstracts in English

Journal Articles

Measurement of neutron-production double-differential cross sections in most-forward direction by proton incidences

Satoh, Daiki; Iwamoto, Yosuke; Ogawa, Tatsuhiko

2017-Nendo Ryoshi Kagaku Gijutsu Kenkyu Kaihatsu Kiko Shisetu Kyoyo Jisshi Hokokusho (Internet), 1 Pages, 2019/08

Many neutrons are produced in forward directions by intermediate-energy proton-induced reactions. While it is known that collective motion in a target nucleus plays important role in this neutron production, validity of theoretical model and nuclear-data library has not been examined well due to a lack of experimental data. Hence, we obtained systematic data of neutron-production double-differential cross section in the most-forward direction. The experiment was performed at TIARA of Takasaki Advanced Radiation Research Institute, QST. 34-MeV proton beams were bombarded upon thin carbon, aluminum, iron, and lead target, and the neutrons produced in the most-forward direction were led to experimental room passing through a collimator. Scintillation detectors were used to the neutron detection. In comparison with the calculation results of PHITS, it was found that the theoretical model INCL always overestimate the cross sections, and the evaluated nuclear-data library JENDL-4.0/HE reproduce the measure spectra better than the INCL does.

Journal Articles

Effect of H$$_{2}$$O$$_{2}$$ concentration on oxidative dissolution of U$$_{2}$$O

Kumagai, Yuta

Hoshasen Kagaku (Internet), (107), p.77 - 78, 2019/04

Reaction of hydrogen peroxide (H$$_{2}$$O$$_{2}$$) with uranium dioxide (UO$$_{2}$$) 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$$_{2}$$ matrix of the spent fuel. This study investigate effect of H$$_{2}$$O$$_{2}$$ concentration on the kinetics and the yield of U(VI) dissolution of this reaction. A series of experiments of the reaction of H$$_{2}$$O$$_{2}$$ with UO$$_{2}$$ powder dispersed in water has been carried out. The experimental results reveal that increase in the H$$_{2}$$O$$_{2}$$ 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 H$$_{2}$$O$$_{2}$$ reaction on the surface of UO$$_{2}$$.

Journal Articles

Molecular dynamics simulations of physical properties of water and cations in montmorillonite interlayer; Application to diffusion model

Yotsuji, Kenji*; Tachi, Yukio; Kawamura, Katsuyuki*; Arima, Tatsumi*; Sakuma, Hiroshi*

Nendo Kagaku, 58(1), p.8 - 25, 2019/00

Molecular dynamics (MD) simulations were conducted to investigate physical properties of water and cations in montmorillonite interlayer nanopores. The swelling behaviors and hydration states were firstly evaluated as functions of interlayer cations and layer charge. The diffusion coefficients of water and cations in interlayer nanopores were decreased in comparison with those in bulk water and came closer to those in bulk water when basal spacing increased. The viscosity coefficients of interlayer water estimated indicated a significant effect of viscoelectricity at 1- and 2-layer hydration states and higher layer charge of montmorillonite. These trends from MD calculations were confirmed to be consistent with existing measured data and previous MD simulation. In addition, model and parameter related to viscoelectric effect used in the diffusion model was refined based on comparative discussion between MD simulations and measurements. The series of MD calculations could provide atomic level understanding for the developments and improvements of the diffusion model for compacted montmorillonite.

Journal Articles

Effect of surface conditions of the filament used in thermal ionization mass spectrometry on an uranium isotopic measurement

Taguchi, Shigeo; Miyauchi, Hironari*; Horigome, Kazushi; Yamamoto, Masahiko; Kuno, Takehiko

Bunseki Kagaku, 67(11), p.681 - 686, 2018/11

In thermal ionization mass spectrometry, de-gassing is one of the important treatments to release impurities of filaments and to minimize the influence of background. In this work, the effect of the surface change in the tungsten filament induced by the conductively heating treatment on uranium isotopic ($$^{235}$$U/$$^{238}$$U) measurement has been investigated. It was found that the conductively heating treatment of the filament has the effect of smoothing the surface of the filament and also has the effect of improving the deposition of the sample on the filament surface. As a result of either these effects, the precision of uranium isotopic ($$^{235}$$U/$$^{238}$$U) measurement was improved.

Journal Articles

Recent progress of radiation physicochemical process (third part)

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.

Journal Articles

Simulation of fluidity, dispersion and mass transfer in an annular centrifugal contactor

Sano, Yuichi; Sakamoto, Atsushi; Takeuchi, Masayuki; Misumi, Ryuta*; Kunii, Kanako*; Todoroki, Kei*; Nishi, Kazuhiko*; Kaminoyama, Meguru*

Kagaku Kogaku Rombunshu, 44(6), p.335 - 340, 2018/11

Concerning an annular centrifugal contactor which has high throughput and separation performance, the effect of operational condition on fluidic and dispersion behavior, which are important to improve the contactor performance, was investigated by computational fluid dynamics (CFD) analysis based on the turbulence model, and the calculated results were validated by experimental data. The liquid phase in the annular zone was gradually divided into two regions vertically with increasing the rotor speed and decreasing the flowrate, and the liquid flow moved toward the center of the housing bottom was generated in the lower annular zone under any operational condition. The droplet size of the dispersed phase in the annular zone decreased with increasing the rotor speed and decreasing the flowrate. These calculation results showed a good agreement with experimental data. The CFD analysis considering mass transfer between aqueous and organic phases was also attempted, and it was confirmed that the change of extraction performance with the rotor speed showed the same tendency as the experimental result.

1061 (Records 1-20 displayed on this page)