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Omer, M.; Shizuma, Toshiyuki*; Koizumi, Mitsuo; Hajima, Ryoichi*; Hashimoto, Satoshi*; Miyamoto, Shuji*
LASTI Annual Report, 24, p.20 - 22, 2023/12
Hashimoto, Shunsuke*; Yamaguchi, Satoshi*; Harada, Masashi*; Nakajima, Kenji; Kikuchi, Tatsuya*; Oishi, Kazuki*
Journal of Colloid and Interface Science, 638, p.475 - 486, 2023/05
Times Cited Count:2 Percentile:60.61(Chemistry, Physical)Recently, it has been reported that anomalous improvement in the thermal conductivity of nanofluid composed of base liquids and dispersed solid nanoparticles, compared to the theoretically predicted value calculated from the particle fraction. Generally, the thermal conductivity values of gases and liquids are dominated by the mean free path of the molecules during translational motion. Herein, we present solid evidence showing the possible contribution of the vibrational behavior of liquid molecules around nanoparticles to increasing these thermal conductivities.
Oka, Hiroshi*; Tanno, Takashi; Yano, Yasuhide; Otsuka, Satoshi; Kaito, Takeji; Hashimoto, Naoyuki*
Journal of Nuclear Materials, 572, p.154032_1 - 154032_8, 2022/12
Times Cited Count:3 Percentile:66.21(Materials Science, Multidisciplinary)9Cr oxide dispersion strengthened steels with slightly different nitrogen concentrations (0.0034 - 0.029 wt%) were prepared and their creep property at 973 K was investigated with microstructural characterization before and after the creep test. The creep strength decreased significantly as the nitrogen concentration increased. Microstructural observation revealed that, in the higher nitrogen concentration specimen, coarse Y-rich inclusions were found along the boundary between transformed ferrite region and residual ferrite region. The solubility difference of nitrogen in and phase would induce the localized increment of nitrogen concentration in the boundary region during the austenitizing process, resulting in the thermodynamic destabilization and subsequent coarsening of the dispersed oxide particles. The rows of creep voids were found near the rupture part of the crept specimen, suggesting that the coarse inclusions were the starting point of creep void formation and the subsequent premature fracture.
Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Nishimura, Koji*; Hashimoto, Taishi*; Tanaka, Yoshimasa*; Kadokura, Akira*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Ogawa, Yasunobu*; et al.
Journal of Space Weather and Space Climate (Internet), 12, p.18_1 - 18_16, 2022/06
Times Cited Count:1 Percentile:20.65(Astronomy & Astrophysics)We identified two energetic electron precipitation (EEP) events during the growth phase of moderate substorms and estimated the mesospheric ionization rate for an EEP event for which the most comprehensive dataset from ground-based and space-born instruments was available. The mesospheric ionization signature reached below 70 km altitude and continued for ~15 min until the substorm onset, as observed by the PANSY radar and imaging riometer at Syowa Station in the Antarctic region. We also used energetic electron flux observed by the Arase and POES 15 satellites as the input for the air-shower simulation code PHITS to quantitatively estimate the mesospheric ionization rate. Combining the cutting-edge observations and simulations, we shed new light on the space weather impact of the EEP events during geomagnetically quiet times, which is important to understand the possible link between the space environment and climate.
Iwamoto, Yosuke; Hashimoto, Shintaro; Sato, Tatsuhiko; Matsuda, Norihiro; Kunieda, Satoshi; elik, Y.*; Furutachi, Naoya*; Niita, Koji*
Journal of Nuclear Science and Technology, 59(5), p.665 - 675, 2022/05
Times Cited Count:9 Percentile:79.99(Nuclear Science & Technology)A benchmark study of PHITS3.24 has been conducted using neutron-shielding experiments listed in the Shielding Integral Benchmark Archive and Database. Five neutron sources were selected, which are generated from (1) 43- and 68-MeV proton-induced reaction on a thin lithium target, (2) 52-MeV proton-induced reaction on a thick graphite target, (3) 590-MeV proton-induced reaction on a thick lead target, (4) 500-MeV proton-induced reaction on a thick tungsten target, and (5) 800-MeV proton-induced reaction on a thick tantalum target. For all cases, overall agreements in the results are satisfactory when using the JENDL-4.0/HE to simulate neutron- and proton-induced reactions up to 200 MeV. However, discrepancies using PHITS default settings are observed in the results. For an accurate neutron-shielding design for accelerator facilities, using JENDL-4.0/HE in the particle and heavy-ion transport code system calculation is favorable.
Kawasaki, Takuro; Fukuda, Tatsuo; Yamanaka, Satoru*; Sakamoto, Tomokazu*; Murayama, Ichiro*; Kato, Takanori*; Baba, Masaaki*; Hashimoto, Hideki*; Harjo, S.; Aizawa, Kazuya; et al.
Journal of Applied Physics, 131(13), p.134103_1 - 134103_7, 2022/04
Times Cited Count:1 Percentile:15.88(Physics, Applied)Nagai, Yasuki*; Kawabata, Masako*; Hashimoto, Shintaro; Tsukada, Kazuaki; Hashimoto, Kazuyuki*; Motoishi, Shoji*; Saeki, Hideya*; Motomura, Arata*; Minato, Futoshi; Ito, Masatoshi*
Journal of the Physical Society of Japan, 91(4), p.044201_1 - 044201_10, 2022/04
Times Cited Count:2 Percentile:44.06(Physics, Multidisciplinary)Recently, Lu is considered as one of the most important medical RIs for treating neuroendocrine tumors. A plan to produce Lu with high purity by using enriched Yb samples with irradiation of deuteron beams in accelerators has been discussed. However, since the other Yb isotopes contained in the Yb sample interacts with deuterons, Lu isotopes other than Lu are produced as impurities. Since the purity of Lu is important for medical use, a method to evaluate the impurity of Lu has been required. In this study, we proposed a new method to estimate production yields of each Lu isotopes in Yb samples with arbitrary isotopic compositions by using excitation functions of Yb()Lu reactions and the particle transport calculation code PHITS. The method plays an important role in discussing the isotopic composition of enriched samples to produce high-purity Lu using accelerators.
Yokoyama, Sumi*; Tsujimura, Norio; Hashimoto, Makoto; Yoshitomi, Hiroshi; Kato, Masahiro*; Kurosawa, Tadahiro*; Tatsuzaki, Hideo*; Sekiguchi, Hiroshi*; Koguchi, Yasuhiro*; Ono, Koji*; et al.
Journal of Radiation Protection and Research, 47(1), p.1 - 7, 2022/03
Background: In Japan, new regulations that revise the dose limit for the lens of the eye (the lens), operational quantities, and measurement positions for the lens dose were enforced in April 2021. Based on the international safety standards, national guidelines, the results of the Radiation Safety Research Promotion Fund of the Nuclear Regulatory Authority, and other studies, the Working Group of Radiation Protection Standardization Committee, the Japan Health Physics Society (JHPS) developed a guideline for radiation dose monitoring for the lens. Materials and Methods: The Working Group of the JHPS discussed the criteria of non-uniform exposure and the management criteria set to not exceed the dose limit for the lens. Results and Discussion: In July 2020, the JHPS guideline was published. The guideline consists of three parts: main text, explanations, and 26 questions. In the questions, the corresponding answers were prepared, and specific examples were provided to enable similar cases to be addressed. Conclusion: With the development of guideline on radiation dose monitoring of the lens, radiation managers and workers will be able to smoothly comply with revised regulations and optimise radiation protection.
Yokoyama, Sumi*; Iwai, Satoshi*; Tsujimura, Norio; Hashimoto, Makoto; Yoshitomi, Hiroshi; Kato, Masahiro*; Kurosawa, Tadahiro*; Tatsuzaki, Hideo*; Sekiguchi, Hiroshi*; Koguchi, Yasuhiro*; et al.
Proceedings of 15th International Congress of the International Radiation Protection Association (IRPA-15) (Internet), 8 Pages, 2022/00
Taruta, Yasuyoshi; Yanagihara, Satoshi*; Hashimoto, Takashi*; Kobayashi, Shigeto*; Iguchi, Yukihiro; Kitamura, Koichi; Koda, Yuya; Tomoda, Koichi
Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 8 Pages, 2020/08
Decommissioning is a long-term project during which generations are expected to change. Therefore, it is necessary to appropriately transfer knowledge and technology to the next generation. In recent years, in the world of decommissioning, attempts have been made to apply advanced technologies such as utilization of knowledge management and virtual reality. This study describes adaptation in decommissioning from the viewpoint of utilizing IT technology called digital twin from the viewpoint of knowledge management.
Ishikawa, Takatsugu*; Fujimura, Hisako*; Fukasawa, Hiroshi*; Hashimoto, Ryo*; He, Q.*; Honda, Yuki*; Hosaka, Atsushi; Iwata, Takahiro*; Kaida, Shun*; Kasagi, Jirota*; et al.
Physical Review C, 101(5), p.052201_1 - 052201_6, 2020/05
Times Cited Count:4 Percentile:44.35(Physics, Nuclear)Tsukada, Kazuaki; Nagai, Yasuki*; Hashimoto, Shintaro; Minato, Futoshi; Kawabata, Masako*; Hatsukawa, Yuichi*; Hashimoto, Kazuyuki*; Watanabe, Satoshi*; Saeki, Hideya*; Motoishi, Shoji*
Journal of the Physical Society of Japan, 89(3), p.034201_1 - 034201_7, 2020/03
Times Cited Count:2 Percentile:21.72(Physics, Multidisciplinary)We found anomalously large yields of Ga, Ga, Zn and Cu by neutron irradiation on a ZnO sample in a polyethylene shield. Neutron beams are generated from the Be() reaction for 50 MeV deuterons. The yields obtained were more than 20 times larger than those in the unshielded sample. On the other hand, the yields of Ga, Ga, Zn and Cu from a metallic Zn sample and the yields of Cu, Ni and Zn from the ZnO and Zn samples were almost insensitive to the shield conditions. This finding would provide us a unique capability of accelerator neutrons to simultaneously produce a large amount of several radioisotopes, including proton induced reaction products, by using a single sample. The experimental data were compared with the yields estimated by using the Particle and Heavy Ion Transport code System and the result was discussed.
Kim, J.*; Yamanaka, Satoru*; Murayama, Ichiro*; Kato, Takanori*; Sakamoto, Tomokazu*; Kawasaki, Takuro; Fukuda, Tatsuo; Sekino, Toru*; Nakayama, Tadachika*; Takeda, Masatoshi*; et al.
Sustainable Energy & Fuels (Internet), 4(3), p.1143 - 1149, 2020/03
Times Cited Count:16 Percentile:63.91(Chemistry, Physical)Sato, Satoshi*; Konno, Chikara; Nakashima, Hiroshi; Shionaga, Ryosuke*; Nose, Hiroyuki*; Ito, Yuji*; Hashimoto, Hirohide*
Journal of Nuclear Science and Technology, 55(4), p.410 - 417, 2018/04
Times Cited Count:1 Percentile:11.34(Nuclear Science & Technology)In order to enhance the neutron shielding performance, we developed concrete with boron of more than 10 wt%. We performed a neutron shielding experiment using the mockup of the newly developed boron-loaded concrete and DT neutrons at FNS in JAEA, and measured the reaction rates of the Nb(n,2n)Nb and Au(n,)Au reactions in the mockup. The calculations were conducted by using MCNP-5.14 and FENDL-2.1. The calculation results agreed well with the measured ones, and we confirmed that the accuracy was very good on the atomic composition data of the boron-loaded concrete and their nuclear data. In addition, we calculated effective dose rates and reaction rates of the Co(n,)Co and Eu(n,)Eu reactions in the boron-loaded concrete and other concretes. It is concluded that the boron-loaded concrete has much better shielding performance for DT neutrons than other concretes.
Tsukada, Kazuaki; Nagai, Yasuki*; Hashimoto, Kazuyuki*; Kawabata, Masako*; Minato, Futoshi; Saeki, Hideya*; Motoishi, Shoji*; Ito, Masatoshi*
Journal of the Physical Society of Japan, 87(4), p.043201_1 - 043201_5, 2018/04
Times Cited Count:10 Percentile:59.94(Physics, Multidisciplinary)Minato, Futoshi; Tsukada, Kazuaki; Sato, Nozomi*; Watanabe, Satoshi*; Saeki, Hideya*; Kawabata, Masako*; Hashimoto, Shintaro; Nagai, Yasuki*
Journal of the Physical Society of Japan, 86(11), p.114803_1 - 114803_6, 2017/11
Times Cited Count:10 Percentile:56.7(Physics, Multidisciplinary)We have measured the yield of Mo, the mother nuclide of Tc used in nuclear diagnostic procedure. Mo was produced by Mo(,)Mo using neutrons with thermal energy up to about 40 MeV, provided by C(,). The Mo yield agrees with an estimated yield with the use of the latest data of C(,) and the evaluated cross section given in the JENDL. Based on this, a new calculation was carried out to produce Mo to seek for a good economical condition. Various conditions such as the MoO sample mass, the distance between the carbon target and the sample, the radius of the deuteron beam, and the neutron irradiation time were considered. The calculated Mo yield indicates that about 30% of the Mo demand in Japan can be fulfilled with a single accelerator. The elusion of Tc from the Mo twice per day would meet about 50% of the Mo demand.
Yamaguchi, Daisuke; Yuasa, Takeshi*; Sone, Takuo*; Tominaga, Tetsuo*; Noda, Yohei*; Koizumi, Satoshi*; Hashimoto, Takeji*
Macromolecules, 50(19), p.7739 - 7759, 2017/10
Times Cited Count:14 Percentile:48.33(Polymer Science)We elucidated the spatial distribution of filler particles in cross-linked poly(styrene--butadiene) rubbers (SBR) developed under a typical fillers/rubbers compounding process as one of dissipative structures formed under a stress field imposed on the given system. The dispersion state of the fillers in SBR was clarified on the basis of hierarchical structures consisting of five structure levels. More specifically, it has the following characteristics depending on the specific interactions: Small, compact clusters build up compact mass-fractal structures, while large, loose clusters build up open mass-fractal structures.
Hayakawa, Takehito; Miyamoto, Shuji*; Hajima, Ryoichi; Shizuma, Toshiyuki; Amano, So*; Hashimoto, Satoshi*; Misawa, Tsuyoshi*
Journal of Nuclear Science and Technology, 53(12), p.2064 - 2071, 2016/12
Times Cited Count:6 Percentile:43.12(Nuclear Science & Technology)We have proposed a new selective isotope transmutation method using photonuclear reactions with quasi-monochromatic -ray beams. This method is based on the fact that the particle threshold of a long-lived fission product (LLFP) such as Zr, Pd, or Se is lower than those of stable isotopes of the same chemical element. Therefore, this method has an excellent advantage that LLFPs cannot, in principle, be produced newly even if the target materials include stable isotopes in addition to a LLFP. Laser Compton scattering -ray sources and neutron capture -rays in nuclear reactors are candidates for this method.
Tonai, Satoshi*; Ito, Shun*; Hashimoto, Yoshitaka*; Tamura, Hajimu; Tomioka, Naotaka*
Journal of Structural Geology, 89, p.19 - 29, 2016/08
Times Cited Count:16 Percentile:48.38(Geosciences, Multidisciplinary)We used the K-Ar ages of clay-sized mineral grains to investigate the timing of activity on the fossil seismogenic Minami-Awa Fault. The K-Ar ages from matrix shale of the mlange range from 85 to 48 Ma and decrease with decreasing amount of detrital mica. In contrast, the K-Ar ages of an ultracataclasite within the fault core are significantly younger, ranging from 29 to 23 Ma, and are unrelated to grain size. This indicates that Ar diffused completely from the ultracataclasite between 29 and 23 Ma. The diffusion of Ar in the ultracataclasite was probably caused by frictional heating or high-temperature fluid migration that occurred when the fault was reactivated. The results indicate that seismogenic faults that separate tectonic mlange from coherent strata in accretionary complex may slip, not only during accretion, but also long after accretion.
Sato, Tatsuhiko; Niita, Koji*; Matsuda, Norihiro; Hashimoto, Shintaro; Iwamoto, Yosuke; Furuta, Takuya; Noda, Shusaku; Ogawa, Tatsuhiko; Iwase, Hiroshi*; Nakashima, Hiroshi; et al.
Annals of Nuclear Energy, 82, p.110 - 115, 2015/08
Times Cited Count:35 Percentile:94.59(Nuclear Science & Technology)The general purpose Monte Carlo Particle and Heavy Ion Transport code System, PHITS, is being developed through a collaboration of several institutes in Japan and Europe. The Japan Atomic Energy Agency is responsible for managing the entire project. PHITS can deal with the transport of nearly all particles, including neutrons, protons, heavy ions, photons, and electrons, over wide energy ranges using various nuclear reaction models and data libraries. This paper briefly summarizes the physics models implemented in PHITS, and introduces some important functions useful for particular purposes, such as an event generator mode and beam transport functions.