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Tanaka, Nobuyuki; Takegami, Hiroaki; Noguchi, Hiroki; Kamiji, Yu; Myagmarjav, O.; Ono, Masato; Sugimoto, Chihiro
Chemical Engineering Science, 299, p.120479_1 - 120479_11, 2024/11
We developed a deep neural network method to predict the composition of the iodine-sulfur process of thermochemical water-splitting hydrogen production using measurable properties. Unlike conventional titration analysis, this approach allows a quick understanding of fluid composition, providing essential information for controlling operating conditions. This study focused on the HI-I-HO three-component system within the IS process. Using Gibbs phase rule, the DNN model was constructed using online measurable parameters, such as temperature, pressure, and density, as input conditions. The model was trained with experimental data, and the structural parameters were tuned. Composition prediction using actual trend data demonstrated good correlation with titration analysis measurements. Furthermore, the local interpretable model-agnostic explanations method was incorporated to gain insights into the significance of input parameters for compositions from the DNN model, providing valuable information on crucial parameters for effective composition control.
Hayashida, Koki*; Tsuda, Yasutaka; Murase, Natsumi*; Yamada, Takashi*; Yoshigoe, Akitaka; Dio, W. A.*; Okada, Michio*
Applied Surface Science, 669, p.160475_1 - 160475_6, 2024/10
Bartz, M.*; King, G. E.*; Bernard, M.*; Herman, F.*; Wen, X.*; Sueoka, Shigeru; Tsukamoto, Sumiko*; Braun, J.*; Tagami, Takahiro*
Earth and Planetary Science Letters, 644, p.118830_1 - 118830_11, 2024/10
Tasaki, Yudai; Narukawa, Takafumi; Udagawa, Yutaka
Journal of Nuclear Science and Technology, 61(10), p.1349 - 1359, 2024/10
Sugiura, Yuki; Ishidera, Takamitsu; Aoyagi, Noboru; Mei, H.; Saito, Takumi*; Tachi, Yukio
Applied Clay Science, 258, p.107476_1 - 107476_10, 2024/09
Tian, Q.*; Feng, L.*; Wu, C.*; Wen, J.*; Qiu, X.*; Tanaka, Kazuya; Onuki, Toshihiko*; Yu, Q.*
Journal of Colloid and Interface Science, 669, p.1006 - 1014, 2024/09
Parisi, A.*; Furutani, K. M.*; Sato, Tatsuhiko; Beltran, C. J.*
Quantum Beam Science (Internet), 8(3), p.18_1 - 18_16, 2024/09
Shimojo, Kojiro; Fujiwara, Iori*; Saito, Takumi*; Oshima, Tatsuya*
Analytical Sciences, 40(8), p.1429 - 1436, 2024/08
Extraction ability of -dioctylthiodiglycolamic acid (T-DODGAA), a soft-base sulfur donor ligand with an amide group and a carboxylic acid connected by a thioether chain, for 56 metal ions have been comprehensively investigated and compared with that of N,N-dioctyldiglycolamic acid (DODGAA) with an etheric oxygen atom, a hard-base donor. The p of the thiodiglycolamic acid framework was determined to be 3.71 0.06 in water (0.1 M LiCl, 25C ) by potentiometric titration, indicating that T-DODGAA is a slightly weaker acid than DODGAA (p = 3.54 0.03). T-DODGAA can quantitatively extract various metal ions from the 56 metal ions through a proton-exchange reaction. T-DODGAA provided higher extraction performance than DODGAA for Hf(IV), Cr(III), Fe(III), Ni(II), Cu(II), Pd(II), Ag(I), Au(III), Hg(II), Al(III), and Ga(III), especially for soft metal ions. Furthermore, to demonstrate the practical feasibility of T-DODGAA for hydrometallurgy and metal recycling, we performed selective separation tests of rare metal ions such as Sc(III), Ni(II), Co(II), Pd(II), Au(III), In(III), and Ga(II) in metal-mixed extraction systems.
Li, F.; Narukawa, Takafumi; Udagawa, Yutaka
Journal of Nuclear Science and Technology, 61(8), p.1036 - 1047, 2024/08
Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)Tamura, Koji; Nakanishi, Ryuzo; Oba, Hironori; Karino, Takahiro; Shibata, Takuya; Taira, Takunori*; Wakaida, Ikuo
Journal of Nuclear Science and Technology, 61(8), p.1109 - 1116, 2024/08
Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)Takei, Hayanori
Journal of Nuclear Science and Technology, 61(8), p.1075 - 1088, 2024/08
Times Cited Count:0 Percentile:0.05(Nuclear Science & Technology)In the proton linear accelerator (linac), the proton beam is unexpectedly interrupted due to the electrical discharge originating from the radio frequency, failure of the device/equipment, or other factors. Do these beam trips occur randomly? Conventionally, it has been implicitly assumed that beam trips occur randomly. In this study, we investigated whether beam trips in the linac of the Japan Proton Accelerator Research Complex (J-PARC) occur randomly to estimate the beam trip frequency in a superconducting proton linac for an accelerator-driven nuclear transmutation system. First, the J-PARC linac was classified into five subsystems. Then, the reliability function for the operation time in each subsystem was obtained using the Kaplan--Meier estimation, a reliability engineering methods. Using this reliability function, the randomness of beam trips was examined. Analysis of five-year operational data for five subsystems of the J-PARC linac showed that beam trips occurred randomly in some subsystems. However, beam trips did not occur randomly in many subsystems of the proton linac, including the ion source and the acceleration cavity, the primary subsystems of the proton linac.
Terada, Atsuhiko; Nagaishi, Ryuji
Journal of Nuclear Science and Technology, 61(8), p.1135 - 1154, 2024/08
In order to elucidate ventilation and exhaust of hydrogen leaked in a partially open space practically, the effects of outer wind on them were studied analytically by using a CFD code in the room of experimental Half-size Hallway model, which has a H release hole on the bottom, one vent on the roof and another vent on the side: external air flowed in the room from the Door vent and then H was discharged outside from the Roof vent. The H concentration distribution in the room was divided into two layers at the height of Door vent, with a high concentration layer above it and a low concentration layer below it, forming a stratified interface. When the wind speed blown into the room increased, the combination of the Realizable k-e; turbulence model and the turbulence Schmidt number of 1.0 improved the reproducibility of the analysis results of H concentration distribution. The trial analysis suggested that the concern that wind would increase the indoor H concentration could be reduced by using the plate with a simple structure in which two plates were crossed on the Roof vent.
Abe, Takumi; Nishihara, Kenji
Journal of Nuclear Science and Technology, 61(8), p.1048 - 1060, 2024/08
Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)Methods of direct disposal of mixed oxide spent fuel (MOXSF) consumed in light water reactors were investigated via heat transfer calculation. The temperature of the buffer material surrounding the waste is the most stringent limitation on the direct disposal of MOXSF. Therefore, the effects on the maximum temperature of the buffer material were examined by changing the occupied area, cooling term of MOXSF, and other parameters considering the direct disposal of uranium spent fuel. The results showed that it is necessary to change the cooling term and disposal depth in addition to the change of the occupied area. Accordingly, some disposal concepts that satisfy the limitation of the maximum buffer material temperature were derived, and estimates revealed that the occupied area per unit waste of the MOXSF is three to five times that of uranium spent fuel.
Yoshida, Keisuke; Kato, Shingo; Okuyama, Shinichi; Ishimori, Yuu; Inoue, Mutsuo*
Journal of Nuclear and Radiochemical Sciences (Internet), 24, p.1 - 12, 2024/08
Ninomiya, Kazuhiko*; Osawa, Takahito; Terada, Kentaro*; Wada, Taiga*; Nagasawa, Shunsaku*; Chiu, I.-H.; Nakamura, Tomoki*; 40 of others*
Meteoritics & Planetary Science, 59(8), p.2044 - 2057, 2024/08
Samples from asteroid Ryugu, brought back by asteroid explorer Hayabusa2 are important for investigating the origin and evolution of the solar system. Here, we report the elemental compositions of a 123 mg Ryugu sample determined with a nondestructive muon elemental analysis method. This method is a powerful tool for determining bulk chemical composition, including light elements such as C, N, and O. From the muonic X-ray spectra with three carbonaceous chondrites, the relationship between the elemental composition and muonic X-ray intensity was determined for each element. Calibration curves showed linearity, and the elemental composition of Ryugu was quantitatively determined. The results reflect the average bulk elemental composition of asteroid Ryugu owing to the large amount of samples. Ryugu has an elemental composition similar to that of Orgueil (CI1), and should be classified as CI1. However, the O/Si ratio of Ryugu is 25% lower than that of Orgueil, indicating that Orgueil may have been seriously contaminated by terrestrial materials after its fall to Earth. These results indicate that the Ryugu sample is more representative than the CI chondrites as a solid material of the solar system.
Costantini, J.-M.*; Ogawa, Tatsuhiko
Quantum Beam Science (Internet), 8(3), p.20_1 - 20_16, 2024/08
A novel Coulomb spike concept is applied to the radiation damage induced in LiF and SiO with about the same mass density (2.65 g cm) by Ni and Kr ions of 1.0-MeV/u energy for about the same electronic energy loss (10 MeV/um). The distribution of ionizations and electrostatic energy gained in the electric field by the ionized atoms is computed with the PHITS code for both targets. Further, the atomic collision cascades induced by these low energy hot ions of about 500 eV are simulated with the SRIM2013 code. It is found that melting is reached in a small volume for SiO due to the energy deposition in the subthreshold events of nuclear collisions induced by the Si and O ions. For LiF, the phonon contribution to the stopping power of the lighter Li and F ions is not sufficient to induce melting, even though the melting temperature is lower than for SiO. The formation of amorphous domains in SiO is likely after fast quenching of the small molten pockets, whereas only point defects may be formed in LiF.
Murmiliuk, A.*; Iwase, Hiroki*; Kang, J.-J.*; Mohanakumar, S.*; Appavou, M.-S.*; Wood, K.*; Almsy, L.*; Len, A.*; Schwrzer, K.*; Allgaier, J.*; et al.
Journal of Colloid and Interface Science, 665, p.801 - 813, 2024/07
The complexity of protein structure limits our ability to predict and tune the properties of the formed nanoparticles. The goal of our research is to elucidate the key triggers of the morphological transition in protein/PE complexes, evaluate their encapsulation efficacy, and assess particle stability by the systematic study of complexes formed by block copolymers with proteins and ionic drugs. We demonstrated that copolymers consisting of PE and neutral hydrophilic block co-assemble with insulin at pH values close to the protein isoelectric point. The insulin arrangement within the particle is controlled by electrostatic forces between protein molecules, and the morphology of the formed particles can be tuned by varying pH and ionic strength.
Sasaki, Yuji; Kaneko, Masashi; Ban, Yasutoshi; Suzuki, Hideya*
Journal of Nuclear Science and Technology, 61(7), p.883 - 893, 2024/07
Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)The mutual separation of Am and Cm is conducted using an alkyl-diamide amine (ADAAM) extractant. ADAAM exhibits extremely high separation factor with respect to Am and Cm separation (5.9) in a nitric acid--dodecane system. The batch-wise multistage extractions are performed using a system containing 0.2 M ADAAM and 1.5 M nitric acid. In this multistage extraction, an organic solvent give 96.5% and 1.06% yields of Am and Cm. After the mutual separation of Am and Cm, an additional extraction step is included to reduce the volumes of these aqueous and organic phases. Taking these steps, Am and Cm can be recovered in just two or three stages in the aqueous phases.
Sato, Yuki; Terasaka, Yuta; Oura, Masatoshi*
Journal of Nuclear Science and Technology, 61(7), p.856 - 870, 2024/07
Shikaze, Yoshiaki
Journal of Nuclear Science and Technology, 61(7), p.894 - 910, 2024/07
Among the radioactive nuclides inside the nuclear reactor buildings emitted by the Fukushima Daiichi nuclear reactor accident, high-energy beta-ray sources, such as strontium-90 and yttrium-90, generate bremsstrahlung photons in the building materials, comprising the wall, floor, and interior structure. Therefore, evaluating the radiation dose of the bremsstrahlung to the workers in the nuclear reactor building is crucial for radiation protection. The precision of the evaluation calculation of the bremsstrahlung dose was investigated by comparing the Particle and Heavy Ion Transport code System (PHITS) and the GEometry ANd Tracking (GEANT4) simulation code results. In the calculation, behind various shielding plates (lead, copper, aluminum, glass, and polyethylene, with thicknesses ranging from 1.0 to 40 mm), the water cylinder was set as the evaluated material, the absorbed dose and the deposited energy spectrum by the bremsstrahlung photons were obtained, and the characteristics and differences for both simulation codes were investigated. In the comparison results of the deposited energy spectrum, the spectral shapes have consistent trends. In the energy range below several tens of keV, a peak is seen in the PHITS spectrum for the lead shielding material. In comparing the absorbed dose under various conditions of the shielding plate for generating bremsstrahlung photons, most results for both codes correlate within an 10% difference for 2.280 MeV beta-ray sources and an 20% difference for 0.5459 MeV beta-ray sources, except for 30% for 20 mm thick lead. Although there were differences in some cases, the evaluation results of the two simulation codes were concluded to correlate well with the above precision.