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Mochizuki, Akihito; Matsui, Hiroya; Nakayama, Masashi; Sakamoto, Ryo*; Shibata, Masahito*; Motoshima, Takayuki*; Jo, Mayumi*
Case Studies in Construction Materials, 22, p.e04648_1 - e04648_20, 2025/07
The properties of low-pH cement used in the geological disposal of radioactive waste may change through atmospheric carbonation and degradation caused by groundwater during the long-term operation of a repository. In this study, we investigated the effects of atmospheric carbonation and groundwater contact on the chemical, microstructural, and transport properties of shotcrete made from low-pH, high-fly-ash silica-fume cement (HFSC) over a period of 16 years in an underground research laboratory. In both carbonated and degraded zones of the HFSC shotcrete, capillary porosity increased for pores of 300 nm in diameter, and the total porosity was higher than in undegraded zones. These changes in porosity may be associated with the decalcification of calcium-silicate-hydrate and decomposition of ettringite. Such changes were minor in altered zones of OPC shotcrete, indicating that HFSC shotcrete is less resistant to atmospheric carbonation and groundwater leaching under the studied conditions. However, the hydraulic conductivity in HFSC was low enough to fulfill the specific functional requirements of low-pH cements for geological disposal.
Ichikawa, Masaya; Gubler, P.; Naruki, Megumi; Yokkaichi, Satoru*
Journal of Subatomic Particles and Cosmology (Internet), 3, p.100018_1 - 100018_5, 2025/06
Li, F.*; Tang, X.*; Fei, Y.*; Zhang, J.*; Liu, J.*; Lang, P.*; Che, G.*; Zhao, Z.*; Zheng, Y.*; Fang, Y.*; et al.
Journal of the American Chemical Society, 147(17), p.14054 - 14059, 2025/04
We synthesized a crystalline graphane nanoribbon (GANR) via pressure-induced polymerization of 2,2'-bipyrazine (BPZ). By performing Rietveld refinement of in situ neutron diffraction data, nuclear magnetic resonance spectroscopy, infrared spectra, and theoretical calculation, we found that BPZ experienced Diels-Alder polymerization between the
stacked aromatic rings, and formed extended boat-GANR structures with exceptional long-range order. The unreacted -C=N- groups bridge the two ends of the boat, and ready for further functionalization. The GANR has a bandgap of 2.25 eV, with booming photoelectric response (
/
=18.8). Our work highlights that the high-pressure topochemical polymerization is a promising method for the precise synthesis of graphane with specific structure and desired properties.
elik, Y.*; Stankovskiy, A.*; Iwamoto, Hiroki; Iwamoto, Yosuke; Van den Eynde, G.*
Annals of Nuclear Energy, 212, p.111048_1 - 111048_12, 2025/03
Times Cited Count:1 Percentile:62.55(Nuclear Science & Technology)Hayashizaki, Kohei; Hirooka, Shun; Yamada, Tadahisa*; Sunaoshi, Takeo*; Murakami, Tatsutoshi; Saito, Kosuke
Ceramics (Internet), 8(1), p.24_1 - 24_12, 2025/03
Kim, M.*; Lee, C.*; Sugita, Yutaka; Kim, J.-S.*; Jeon, M.-K.*
Geomechanics for Energy and the Environment, 41, p.100628_1 - 100628_9, 2025/03
Times Cited Count:0 Percentile:0.00(Energy & Fuels)This study investigates the impact of primary variables selection on the modeling of non-isothermal two-phase flow, by using the numerical work on the full-scale Engineered Barrier System (EBS) experiment conducted at Horonobe URL as part of the DECOVALEX-2023 project. A validated numerical model is employed to simulate the coupled thermo-hydrological behavior of heterogeneous porous media within the EBS. Two different primary variable schemes are compared in discretizing the governing equations, revealing significant difference in results.
Nakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Rovira Leveroni, G.; Kimura, Atsushi
Journal of Nuclear Science and Technology, 62(3), p.300 - 307, 2025/03
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Gubler, P.; Ichikawa, Masaya; Song, T.*; Bratkovskaya, E.*
Physical Review C, 111(3), p.034908_1 - 034908_12, 2025/03
Times Cited Count:0Hizukuri, Kyoko*; Fujibuchi, Toshio*; Han, D.*; Arakawa, Hiroyuki*; Furuta, Takuya
Radiological Physics and Technology, 18(1), p.196 - 208, 2025/03
One of the radiation protection measures for medical personnel engaged in X-ray fluoroscopy is the use of radiation-protective plates and a simulation tool to evaluate effect of the plates is desired. Monte Carlo simulation has an advantage of being able to accurately calculate the interaction between radiations and various objects present in the X-ray room. However, Monte Carlo simulation has a disadvantage of being computationally time-consuming. Therefore, we developed a new simplified method to calculate the dose distribution in a short time with the presence of protective plates using pre-computed directional vectors (SCV). Using the Monte Carlo code PHITS, we simulated the ambient dose equivalent distribution the X-ray fluoroscopy room without the presence of protective plates. Assuming the dose at each voxel was all contributed from radiations in the direction indicated by the directional vector, the shielding effect of the protective plates for the dose at the voxel was determined whether the line toward backtrace of the directional vector has a intersect with the protective plate or not. With SCV, the computational time for the whole dose distribution with the presence of a protective plate was reduced approximately 1/6000 of the full PHITS simulation keeping the good accuracy to evaluate the effect of the plate.
Hojo, Tomohiko*; Koyama, Motomichi*; Kumai, Bakuya*; Zhou, Y.*; Shibayama, Yuki; Shiro, Ayumi*; Shobu, Takahisa; Saito, Hiroyuki*; Ajita, Saya*; Akiyama, Eiji*
ISIJ International, 65(2), p.284 - 296, 2025/02
Matsumura, Taichi; Okumura, Keisuke; Sakamoto, Masahiro; Terashima, Kenichi; Riyana, E. S.; Kondo, Kazuhiro*
Nuclear Engineering and Design, 432, p.113791_1 - 113791_9, 2025/02
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Yang, X.*; Che, G.*; Wang, Y.*; Zhang, P.*; Tang, X.*; Lang, P.*; Gao, D.*; Wang, X.*; Wang, Y.*; Hattori, Takanori; et al.
Nano Letters, 25(3), p.1028 - 1035, 2025/01
Times Cited Count:0 Percentile:0.00(Chemistry, Multidisciplinary)Saturated sp-carbon nanothreads (CNTh) have garnered significant interest due to their predicted high Young's modulus and thermal conductivity. While the incorporation of heteroatoms into the central ring has been shown to influence the formation of CNTh and yield chemically homogeneous products, the impact of pendant groups on the polymerization process remains underexplored. In this study, we investigate the pressure-induced polymerization of phenol, revealing two phase transitions occurring below 0.5 and 4 GPa. Above 20 GPa, phenol polymerizes into degree-4 CNThs featuring hydroxyl and carbonyl groups. Hydrogen transfer of hydroxyl groups was found to hinder the formation of degree-6 nanothreads. Our findings highlight the crucial role of the hydroxyl group in halting further intracolumn polymerization and offer valuable insights for future mechanism research and nanomaterial synthesis.
Terasaka, Yuta; Sato, Yuki; Furuta, Yoshihiro*; Kubo, Shin*; Ichiba, Yuta*
Nuclear Instruments and Methods in Physics Research A, 1070(2), p.170021_1 - 170021_9, 2025/01
Times Cited Count:0 Percentile:0.00(Instruments & Instrumentation)Abreu, L. M.*; Gubler, P.; Khemchandani, K. P.*; Martnez Torres, A.*; Hosaka, Atsushi
Physics Letters B, 860, p.139175_1 - 139175_7, 2025/01
Times Cited Count:1 Percentile:0.00(Astronomy & Astrophysics)Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*
JAEA-Review 2024-016, 61 Pages, 2024/12
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2022. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2022, this report summarizes the research results of the "Development of a high-resolution imaging camera for alpha dust and high-dose rate monitor" conducted in FY2022. The present study aims to develop a high-resolution imaging camera for alpha dust and a high-dose rate monitor. To realize the high-resolution imaging camera for alpha dust, we have developed novel scintillation materials with emission bands of 500-800 nm. Moreover, we have prepared several materials for the camera and software. We have also developed novel scintillation materials with emission bands of 650-1,000 nm, and simulation studies have been conducted for the high-dose-rate monitor system consisting of optical fiber.
Endo, Akira
Annals of the ICRP, 52(4), p.5 - 7, 2024/12
In its Publication 155, International Commission on Radiological Protection (ICRP) has developed data on the Specific Absorbed Fraction (SAF) for reference males and females at ages of newborn, 1 year, 5 years, 10 years, and 15 years. The SAF represents the fraction of energy emitted within a source region which is absorbed in a target region per mass of the target region and is essential for calculating absorbed doses in organs or tissues for internal exposure. By combining the data of Publication 155 with the SAF data for reference adult males and females already published as Publication 133, an SAF dataset for the calculation of age-dependent dose coefficients for members of the public for environmental intakes of radionuclides has been completed. This, together with revised biokinetic models and nuclear decay data, means that the key building blocks for calculating new dose coefficients are in place. The outcome will soon be available in a series of ICRP Publications of Dose Coefficients for Intakes of Radionuclides by Members of the Public.
Sugimoto, Chihiro; Myagmarjav, O.; Tanaka, Nobuyuki; Noguchi, Hiroki; Takegami, Hiroaki; Kubo, Shinji
International Journal of Hydrogen Energy, 95, p.98 - 107, 2024/12
Times Cited Count:0 Percentile:0.00(Chemistry, Physical)Shigyo, Nobuhiro*; Furuta, Takuya; Iwamoto, Yosuke
JAEA-Conf 2024-002, 216 Pages, 2024/11
The 2023 Symposium on Nuclear Data was held at Tokai Industry and Information Plaza "iVil" on November 15-17, 2023. The symposium was organized by the Nuclear Data Division of the Atomic Energy Society of Japan (AESJ) in cooperation with Radiation Engineering Division of AESJ, North Kanto Branch of AESJ, Investigation Committee on Nuclear Data in AESJ, Nuclear Science and Engineering Center of Japan Atomic Energy Agency, and High Energy Accelerator Research Organization. In the symposium, tutorials "Overview of the nuclear data processing code, FRENDY version 2" was proposed and held. Two sessions of lectures and discussions were held: "Recent Topics on Nuclear Data and Particle and Heavy Ion Transport code System (PHITS)". In addition, recent research progress on experiments, nuclear theory, evaluation, benchmark, and applications were presented in the poster session. The total number of participants was 108 participants. Each oral and poster presentation was followed by an active question and answer session. This report consists of a total of 36 papers including 17 oral and 19 poster presentations.
Uesawa, Shinichiro; Yoshida, Hiroyuki
Journal of Nuclear Science and Technology, 61(11), p.1438 - 1452, 2024/11
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)We developed a deep learning-based bubble detector with a Shifted window Transformer (Swin Transformer) to detect and segment individual bubbles among overlapping bubbles. To verify the performance of the detector, we calculated its average precision (AP) with different number of training images. The mask AP increased with the increase in the number of training images when there were less than 50 images but remained constant when there were more than 50 images. It was observed that the AP for the Swin Transformer and ResNet were almost the same when there were more than 50 images; however, when few training images were used, the AP of the Swin Transformer were higher than that of the ResNet. Furthermore, with regard to the increase in void fraction, the AP of the Swin Transformer showed a decrease similar to that in the case of the ResNet; however, for few training images, the AP of the Swin Transformer was higher than that of the ResNet in all void fractions. Moreover, we confirmed the detector trained with synthetic bubble images was able to segment overlapping bubbles and deformed bubbles in a bubbly flow experiment. Thus, we verified that the new bubble detector with Swin Transformer provided higher AP than the detector with ResNet for fewer training images.
Sako, Hiroyuki; Ichikawa, Masaya; Naruki, Megumi; Sakaguchi, Takao; Sato, Susumu; 12 of others*
Journal of Subatomic Particles and Cosmology (Internet), 1-2, p.100012_1 - 100012_7, 2024/11