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thin filmsIshigami, Keisuke*; Yoshimatsu, Kohei*; Toyota, Daisuke*; Takizawa, Masaru*; Yoshida, Teppei*; Shibata, Goro*; Harano, Takayuki*; Takahashi, Yukio*; Kadono, Toshiharu*; Verma, V. K.*; et al.
Physical Review B, 92(6), p.064402_1 - 064402_5, 2015/08
Times Cited Count：45 Percentile：84.02(Materials Science, Multidisciplinary)
-coated FePt nanoparticles studied by X-ray magnetic circular dichroismTakahashi, Yukio*; Kadono, Toshiharu*; Yamamoto, Shimpei*; Singh, V. R.*; Verma, V.*; Ishigami, Keisuke*; Shibata, Goro*; Harano, Takayuki*; Takeda, Yukiharu; Okane, Tetsuo; et al.
Physical Review B, 90(2), p.024423_1 - 024423_5, 2014/07
Times Cited Count：11 Percentile：44.58(Materials Science, Multidisciplinary)Takahashi, Toshiharu*; Minehara, Eisuke; Hajima, Ryoichi; Nishimori, Nobuyuki; Sawamura, Masaru; Nagai, Ryoji; Kikuzawa, Nobuhiro; Iijima, Hokuto; Nishitani, Tomohiro; Okuda, Shuichi*
Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.523 - 525, 2006/00
no abstracts in English
Takahashi, Toshiharu*; Minehara, Eisuke; Hajima, Ryoichi; Sawamura, Masaru; Nagai, Ryoji; Kikuzawa, Nobuhiro; Iijima, Hokuto; Nishitani, Tomohiro; Okuda, Shuichi*
Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.498 - 500, 2005/07
no abstracts in English
Hajima, Ryoichi; Minehara, Eisuke; Sawamura, Masaru; Nagai, Ryoji; Kikuzawa, Nobuhiro; Iijima, Hokuto; Nishitani, Tomohiro; Takahashi, Toshiharu*; Okuda, Shuichi*
Proceedings of 27th International Free Electron Laser Conference (FEL 2005) (CD-ROM), p.301 - 304, 2005/00
no abstracts in English
Matsuda, Yasuhiro*; Ueda, Yuji*; Nojiri, Hiroyuki*; Takahashi, Toshiharu*; Inami, Toshiya; Owada, Kenji; Murakami, Yoichi; Arima, Takahisa*
Physica B; Condensed Matter, 346-347, p.519 - 523, 2004/04
Times Cited Count：51 Percentile：86.12(Physics, Condensed Matter)A very small capacitor bank and miniature pulsed magnets have been developed to perform high-field synchrotron radiation experiments. A 20T pulsed field can be generated using an energy of 1kJ with typical pulse duration about 1ms. Electron spin resonance experiments in millimeter wave range and high-field X-ray diffraction experiments have been done successfully.
Maekawa, I.*; Takahashi, Minoru; Muramatsu, Toshiharu; *; Ninokata, Hisashi; Aoki, Tadao
PNC TN952 84-11, 101 Pages, 1984/07
COMMIX-1A is a single phase multi-dimensional analysis code for thermal-hydraulics within components of nuclear power plants. The code was introduced from the Argonne National Laboratory in the U.S. in 1983. It has been extensively used for sodium and water analysis and now its improvement and validation programs are under way at the Reactor Engineering Section of OEC/PNC. This report is written based on the materials distributed at COMMIX-1A Workshop, 15th and 16th in May, 1984 which offered PNC engineers the chance to use the code and to get familiarity with it for the solution of thermal hydraulic problems of their own fields. This report consists of the following contents: (1) outline of COMMIX-1A, (2) capability and limitation of the code, (3) usage experiances of the code, (4) main input data description and (5) sample problems.
Takahashi, Minoru; Maekawa, I.*; Tamura, Shinji*; Muramatsu, Toshiharu; Hasegawa, Y.*; Ninokata, Hisashi; Aoki, Tadao
PNC TN952 84-08, 157 Pages, 1984/06
COMMIX-1A is a single-phase three-dimensional thermal-hydraulic analysis code with finite difference method developed at U.S. Argonne National Laboratory. ICE version (Ver. 3.0) of COMMIX-1A was released from ANL to PNC through U.S. NRC in 1981. Then, graphics package compatible with version 10.2 of COMMIX-1A was released to PNC in November, 1982, and SIMPLER version (Ver. 12.0) of COMMIX-1A (fixed version) was released in January, 1983. The SIMPLER version and the graphics program have been modified and used for the following analyses at the Reactor Engineering Section: (1)analysis of MONJU upper plenum thermal stratification tests in sodium and in water, (2)post evaluation of JOYO Mark-I natural circulation test, and (3)analysis of water test for thermal hydraulics in pool-type LMFBR hot plenum. After the modification and the experience of COMMIX application at RES, we have made the code accessible for general users in PNC. We have prepared this COMMIX-1A input manual in Japanese so that the user can set up input data and operate the code with great ease for the interim use. The present document consists of the following contents: (i)COMMIX-1A input description both in Japanese and in English, (ii)graphics program input description in Japanese, and (iii)JCL for execution of COMMIX-1A and the graphics program.
Hajima, Ryoichi; Takahashi, Toshiharu*; Nagai, Ryoji; Sawamura, Masaru; Kikuzawa, Nobuhiro; Nishimori, Nobuyuki; Iijima, Hokuto; Nishitani, Tomohiro; Okuda, Shuichi*; Minehara, Eisuke
no journal, ,
no abstracts in English
Cs on the continental shelf off FukushimaOtosaka, Shigeyoshi*; Misono, Toshiharu; Dohi, Terumi; Tsuruta, Tadahiko; Takahashi, Yoshio*; Sugihara, Naoko*; Obata, Hajime*; Ikenoue, Takahito*; Jimi, Naoto*; Hookabe, Natsumi*
no journal, ,
no abstracts in English
Otosaka, Shigeyoshi*; Aono, Tatsuo*; Fukuda, Miho*; Kambayashi, Shota*; Misono, Toshiharu; Dohi, Terumi; Tsuruta, Tadahiko; Suzuki, Takashi; Takahashi, Yoshio*; Sugihara, Naoko*; et al.
no journal, ,
While the amount of cesium-137 (Cs: half-life 30.1 years) accumulated on the seabed due to the accident of the Fukushima Daiichi Nuclear Power Plant (0.1-0.2 PBq) is only about 1 to 2% of the total amount of Cs transported to the ocean, it has been reported that it will remain for a long time in the coastal areas. On the other hand, long-term migration process of the sedimentary radiocesium and the impact on the ecosystem near the seafloor remain unknown. In this presentation, we will give an overview of the distribution and behavior of Cs, especially on the seafloor along the coast of Fukushima, and report the latest results on the processes I the seafloor that should be considered on decadal timescale.
Aono, Tatsuo*; Nishikawa, Jun*; Otosaka, Shigeyoshi*; Takata, Hyoe*; Misono, Toshiharu; Nakanishi, Takahiro; Miura, Hikaru*; Kambayashi, Shota*; Fukuda, Miho*; Sakurada, Masanobu*; et al.
no journal, ,
From 2016 to 2020, the Tohoku Marine Ecosystem Research Vessel Shinsei-maru conducted four research cruises on the dynamics and bioavailability of radionuclides around off Fukushima. Seawater, sediments and organisms were collected mainly around off the Fukushima Daiichi Nuclear Power Plant (FDNPS). The purpose of those cruises is to observe the flux of radionuclides released into the ocean by the FDNPS accident and to understand the bioavailability of radionuclides. In order to understand the contaminated levels of the marine environment, the concentration of radioactive cesium (Cs) in seawater and sediments around off Fukushima was investigated. As a result, the concentration range of dissolved Cs-137 in the surface seawater near the FDNPS from 2016 to 2018 was 10-23 mBq/L, but decreased to 7 mBq/L in 2020. In terms of points, the concentrations of dissolved Cs-137 tended to decrease with time. On the other hand, in sediments, the Cs-137 concentrations were higher in the surface layer (0-2 cm) than the deep layer from 2016 to 2017 and tended to decrease with depth, but after 2018, subsurface vertical maximum of Cs-137 concentrations was observed at some stations. Although these concentrations tended to increase in the subsurface layer, the concentrations in the sediment also tended to decrease with time. In this presentation, we report on the concentration variation of Cs-137 and their characteristics in seawater and sediments around off Fukushima.
Aono, Tatsuo*; Nishikawa, Jun*; Otosaka, Shigeyoshi*; Takata, Hyoe*; Misono, Toshiharu; Nakanishi, Takahiro; Miura, Hikaru*; Fukuda, Miho*; Kambayashi, Shota*; Sakurada, Masanobu*; et al.
no journal, ,
From 2016 to 2020, four research voyages were conducted to investigate the dynamics of radioactive materials in the waters around Fukushima. Seawater and sediment samples were collected in the waters off the Fukushima Daiichi Nuclear Power Plant (FDNPS). The concentration of radioactive cesium (Cs) in seawater and sediment off the coast of Fukushima was surveyed to understand the status of the marine environment. As a result, no significant changes were observed in both seawater and sediment from 2016 to 2020.
Aono, Tatsuo*; Fukuda, Miho*; Sakurada, Masanobu*; Takahashi, Hiroyuki*; Yamazaki, Shinnosuke*; Kambayashi, Shota*; Misono, Toshiharu; Nakanishi, Takahiro; Miura, Hikaru*; Nishikawa, Jun*; et al.
no journal, ,
From 2016 to 2020, R/V Shinsei-maru of JAMSTEC conducted four research cruises on the dynamics and bioavailability of radionuclides around off Fukushima. Seawater, sediments and organisms were collected mainly around off the Fukushima Daiichi Nuclear Power Plant (FDNPS). The purpose of those cruises is to observe the flux of radionuclides released into the ocean by the FDNPS accident and to understand the bioavailability of radionuclides. In order to understand the contaminated levels of the marine environment, the concentration of radiocaesium (Cs) in seawater and sediments around off Fukushima was investigated.
Wakai, Eiichi; Shibayama, Tamaki*; Noto, Hiroyuki*; Furuya, Kazuyuki*; Iwamoto, Yosuke; Wakui, Takashi; Makimura, Shunsuke*; Ishida, Taku*; Ando, Masami*; Sato, Koichi*; et al.
no journal, ,
In fields such as nuclear power and high-energy accelerator target systems, radiation causes degradation of materials and equipment, so materials with high durability and excellent functionality are expected to be created. High-entropy alloys (HEA) are expected to have high irradiation resistance and often have high strength and good ductility. In recent years, research and development is underway worldwide for various applications. In this study, Fe- and Ti-based and W-based HEAs composed of low activation elements (free of Ni and Co) were fabricated. These materials were subjected to X-ray diffraction, microstructural observation, hardness, magnetism, electrical resistance, STEM (or TEM, SEM) and EDS, ultrasonic measurements, and hot isostatic pressing (HIP). Ion irradiation, pulsed laser irradiation, and pulsed electron beam irradiation were also performed on some of the samples to investigate their response characteristics. These HEAs were much harder than normal alloys, and the magnetic properties and related microstructural analysis of Fe-based HEAs revealed that they have interesting properties such as micro magnetic domain structures. In particular, for Fe- and W-based HEAs, the changes in crystal structure, orientation, and internal microstructure induced by HIP treatment and the accompanying effects of high temperature and pressure had a significant effect on magnetic properties and material strength properties. Furthermore, the irradiation response properties of Fe-based HEAs have been characterized.
-phase based titanium alloysWakai, Eiichi; Ishida, Taku*; Kano, Sho*; Shibayama, Tamaki*; Sato, Koichi*; Noto, Hiroyuki*; Makimura, Shunsuke*; Furuya, Kazuyuki*; Yabuuchi, Atsushi*; Yoshiie, Toshimasa*; et al.
no journal, ,
Titanium materials have been applied to beam window materials and beam dumps in large accelerator systems because of their low specific gravity, high corrosion resistance, strength, and other advantages. As the beam power becomes higher, further improvement of irradiation resistance is required. We have investigated further the properties of titanium alloys based on the -phase, and it was found that Ti-15-3-3-3 alloys have excellent irradiation resistance when subjected to ion irradiation. In order to investigate the cause of this, microstructures and point defects in this and related materials were evaluated by TEM, positron lifetime measurement, electrical resistivity, and stress-induced changes, among others. In addition, we have recently begun to develop a prototype of a titanium-based high-entropy alloy based on -titanium, which is attracting worldwide attention and is being developed, and have also begun to evaluate the emotional properties of this alloy. We have examined the various properties of this material and found that it has considerably higher strength than conventional iron- and titanium-based materials.
Wakai, Eiichi; Noto, Hiroyuki*; Shibayama, Tamaki*; Iwamoto, Yosuke; Ishida, Taku*; Sato, Koichi*; Yabuuchi, Atsushi*; Yoshiie, Toshimasa*; Takahashi, Toshiharu*; Kobayashi, Yasuhiro*; et al.
no journal, ,
In recent years, it has been reported that high-entropy alloys (HEA) have high strength but good ductility, and they are being researched and developed by cutting-edge research institutions around the world with the aim of finding various applications in progress. In this study, we considered several Fe-based, W-based, and Ti-based HEAs, excluding Co and Ni elements, in order to aim for use in high radiation fields and considering low-activation properties. These materials mainly have a bcc crystal structure and were fabricated using a melting method and their material properties were evaluated. As a result, it was found that Fe-based HEA has properties that exceed the hardness of pure W and has excellent irradiation resistance. In addition, a Ti-based HEA that can be subjected to high-temperature forging and high-temperature rolling has been found, and evaluation of the optimal heat treatment temperature is progressing. The hardness of W-based HEA increased through Hot Isostatic Pressing (HIP) treatment, and it was found to have the world's highest hardness among HEA materials.
