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Ikeuchi, Hirotomo; Sasaki, Shinji; Onishi, Takashi; Nakayoshi, Akira; Arai, Yoichi; Sato, Takumi; Ohgi, Hiroshi; Sekio, Yoshihiro; Yamaguchi, Yukako; Morishita, Kazuki; et al.
JAEA-Data/Code 2023-005, 418 Pages, 2023/12
JAEA-Data-Code-2023-005-01.pdf:24.59MBJAEA-Data-Code-2023-005-02.pdf:32.18MB
For safe and steady decommissioning of Tokyo Electric Power Company Holdings' Fukushima Daiichi Nuclear Power Station (1F), information concerning composition and physical/chemical properties of fuel debris generated in the reactors should be estimated and provided to other projects conducting the decommissioning work including the retrieval of fuel debris and the subsequent storage. For this purpose, in FY2021, samples of contaminants (the wiped smear samples and the deposits) obtained through the internal investigation of the 1F Unit 2 were analyzed to clarify the components and to characterize the micro-particles containing uranium originated from fuel (U-bearing particles) in detail. This report summarized the results of analyses performed in FY2021, including the microscopic analysis by SEM and TEM, radiation analysis, and elemental analysis by ICP-MS, as a database for evaluating the main features of each sample and the probable formation mechanism of the U-bearing particles.
and O in a reaction cell in triple quadrupole inductively coupled plasma mass spectrometryKazama, Hiroyuki; Konashi, Kenji*; Suzuki, Tatsuya*; Koyama, Shinichi; Maeda, Koji; Sekio, Yoshihiro; Onishi, Takashi; Abe, Chikage*; Shikamori, Yasuyuki*; Nagai, Yasuyoshi*
Journal of Analytical Atomic Spectrometry, 38(8), p.1676 - 1681, 2023/07
Times Cited Count：0 Percentile：0.02(Chemistry, Analytical)Naito, Fujio*; Anami, Shozo*; Ikegami, Kiyoshi*; Uota, Masahiko*; Ouchi, Toshikatsu*; Onishi, Takahiro*; Oba, Toshiyuki*; Obina, Takashi*; Kawamura, Masato*; Kumada, Hiroaki*; et al.
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1244 - 1246, 2016/11
The proton linac installed in the Ibaraki Neutron Medical Research Center is used for production of the intense neutron flux for the Boron Neutron Capture Therapy (BNCT). The linac consists of the 3-MeV RFQ and the 8-MeV DTL. Design average beam current is 10mA. Target is made of Beryllium. First neutron production from the Beryllium target was observed at the end of 2015 with the low intensity beam as a demonstration. After the observation of neutron production, a lot of improvement s was carried out in order to increase the proton beam intensity for the real beam commissioning. The beam commissioning has been started on May 2016. The status of the commissioning is summarized in this report.
Kitamura, Akihiro; Kurikami, Hiroshi; Yamaguchi, Masaaki; Oda, Yoshihiro; Saito, Tatsuo; Kato, Tomoko; Niizato, Tadafumi; Iijima, Kazuki; Sato, Haruo; Yui, Mikazu; et al.
Nuclear Science and Engineering, 179(1), p.104 - 118, 2015/01
Times Cited Count：8 Percentile：56.13(Nuclear Science & Technology)The prediction of the distribution and fate of radioactive materials eventually deposited at surface in the Fukushima area is one of the main objectives and expected to be achieved in an efficient manner. In order to make such prediction, a number of mathematical models of radioactive contaminants, with particular attention on cesium, on the land and in rivers, lakes, and estuaries in the Fukushima area are developed. Simulation results are examined with the field investigations simultaneously implemented. The basic studies of the adsorption/absorption mechanism of cesium and soils have been performed to shed light on estimating distribution coefficient between dissolved contaminant and particulate contaminant.
Cs distribution in Fukushima after the Fukushima Dai-ichi Nuclear Power Plant accident; A Parameter sensitivity analysisYamaguchi, Masaaki; Kitamura, Akihiro; Oda, Yoshihiro; Onishi, Yasuo*
Journal of Environmental Radioactivity, 135, p.135 - 146, 2014/09
Times Cited Count：38 Percentile：72.86(Environmental Sciences)We applied a model, to predict long term cesium distribution on Fukushima area, based on the USLE and simple sediment discharge formulas. Sensitivity analysis was conducted here to narrow the range of the output results due to the uncertainties of parameters. The preliminary calculation indicated significant deposition of sand portion within river basins. On the other hand the most of the eroded silt and clay portions were transported downstream to the river mouths. Annual sediment outflow into the ocean from Abukuma River and its total from the other 13 river basins vary between calculation cases based on the variation of land use, landform or precipitation. On the other hand, contributions of those parameters are relatively small for Cs concentration within transported soil. This indicates the total amount of Cs outflow into the ocean could be controlled by amount of soil erosion and transport, and total amount of Cs remaining within the basin.
Yamaoka, Shingo; Shimizu, Yuka*; Fukuda, Yoshihiro*; Shobu, Takahisa; Konishi, Hiroyuki
JAEA-Technology 2014-027, 21 Pages, 2014/08
JAEA-Technology-2014-027.pdf:28.95MB
At SPring-8 synchrotron radiation beamlines, it is essential to maintain a vacuum between the radiation source and the experimental station. This is achieved by using scroll pumps and turbo molecular pumps. However, scroll pump malfunctions have been reported at BL22XU. Since many of the pumps are located inside radiation-shielding hutches, malfunctions often go un-noticed. As a result, operations can continue despite the malfunction. To facilitate the early detection of scroll pump malfunctions, we have developed a "scroll pump operating status monitoring system (SCP-MS)". The system simultaneously measures motor current and vacuum pressure at the scroll pump. It is possible to monitor pumps from outside of the shielding hutch, something which was not possible until now. The (SCP-MS) has been installed to monitor scroll pumps in actual operation, to monitor the change of the motor current value and vacuum pressure. We report on the detail of the system.
Cs distribution on territory of FukushimaKitamura, Akihiro; Yamaguchi, Masaaki; Oda, Yoshihiro; Kurikami, Hiroshi; Onishi, Yasuo*
Transactions of the American Nuclear Society, 109(1), p.153 - 155, 2013/11
Long term Cs transport and its future distribution on the territory of Fukushima were predicted based on the USLE and the GIS. By modeling the soil erosion, transport, and deposition, we simulated the future distributions of air dose rates of Cs in mSv/h for 2, 6 and 21 years after the accident. The predictions made by METI were compared with the present results. The predictions of relatively high air dose rate areas were consistently matched between the two models over time. However, our model seemed to predict the decreasing rate of the Cs concentration with time to be slightly less than that of METI prediction. Some portions of the results obtained in the present study were used to provide influxes of sediments and Cs as boundary conditions and lateral inflows for the hydraulic river model.
Yoshida, Kiyoshi; Kizu, Kaname; Murakami, Haruyuki; Kamiya, Koji; Honda, Atsushi; Onishi, Yoshihiro; Furukawa, Masato; Asakawa, Shuji; Kuramochi, Masaya; Kurihara, Kenichi
Fusion Engineering and Design, 88(9-10), p.1499 - 1504, 2013/10
Times Cited Count：6 Percentile：44.02(Nuclear Science & Technology)The modifying of the JT-60U magnet system to the superconducting coils (JT-60SA) is progressing as a satellite facility for ITER by both parties of Japanese government and European commission (EU) in the Broader Approach agreement. The magnet system for JT-60SA consists of 18 Toroidal Field (TF) coils, a Central Solenoid (CS) with 4 modules, and 6 Equilibrium Field (EF) coils. The manufacturing of the JT-60SA magnet system is in progress in EU and Japan. The JT-60SA superconducting magnet system generates an average heat load of 3.2 kW at 4 K to the cryoplant, from nuclear and thermal radiation, conduction and electromagnetic heating, and requires current supplies 20 kA for 4 CS modules and 6 EF coils, 25.7 kA to 18 TF coils. The helium flow to remove this heat, consisting of supercritical helium at pressures up to 0.5 MPa and temperature between 4.4-4.8 K, is distributed to the coils and structures through the valve box (VB) from the cryoline connecting to the auxiliary cold box located outside the torus hall. The feeders also contain the electrical supplies from the current lead transitions to room temperature to the coil. The feeder components consist of the in-cryostat feeders with flexible parts to allow coil operational displacements from the connection pipes out of the cryostat, including S-bend conductor to allow differential thermal contraction and the coil terminal boxes (CTBs) with HIS current leads. A measurement and control system is required to monitor and control these coils and feeders for safety and optimal operational availability. For each coil, both current and supercritical helium are supplied from external systems and are controlled from a central system as part of the regular operation with plasma pulses. Quench detection instruments for superconducting coils, feeders and HTS current leads are provided as a separate, stand alone system.
Kamiya, Koji; Onishi, Yoshihiro; Ichige, Toshikatsu; Furukawa, Masato; Murakami, Haruyuki; Kizu, Kaname; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Mizumaki, Shoichi*
Proceedings of 24th International Cryogenic Engineering Conference (ICEC 24) and International Cryogenic Materials Conference 2012 (ICMC 2012) (CD-ROM), p.587 - 590, 2012/05
The JT-60 plans to be upgraded to a full-superconducting tokamak referred as the JT-60 Super Advance (JT-60SA) as one of the JA-EU broader approach projects. In the JT-60SA, the superconducting magnets are surrounded by thermal shield cooled at 80 K, which is categorized into 3 groups; the vacuum vessel thermal shield (VVTS), the port thermal shield (PTS) and the cryostat thermal shield (CTS). In this study, seismic analysis was conducted for the thermal shield to confirm the soundness of the latest design, taking the dynamical analysis into account. Trial manufacturing of a 10 degree outer VVTS was also conducted. The outer VVTS was subsequently assembled with already existing inner VVTS to measure the total tolerance (manufacturing plus assembly). It was found that the total tolerance was 5.2 mm which is less than the target tolerance of 10 mm. Finally, concept and the current status of the JT-60SA cryodistribution design are reported.
Osaka, Masahiko; Donomae, Takako; Ichikawa, Shoichi; Sasaki, Shinji; Ishimi, Akihiro; Inoue, Toshihiko; Sekio, Yoshihiro; Miwa, Shuhei; Onishi, Takashi; Asaka, Takeo; et al.
Proceedings of 1st Asian Nuclear Fuel Conference (ANFC), 2 Pages, 2012/03
Support system for training and education of future expert in hot laboratories of Oarai-JAEA, named FEETS, is presented. The system has been established based on research results on both characterization of Oarai hot laboratory and user-needs. Various programs under FEETS are also introduced.
Okamura, Masachika*; Hase, Yoshihiro; Onishi, Noboru*; Narumi, Issei; Tanaka, Atsushi
JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 105, 2012/01
filmsHojo, Ikuko*; Matsumoto, Yoshihiro; Maruyama, Takashi*; Nagamatsu, Shinichi*; Entani, Shiro; Sakai, Seiji; Konishi, Takehisa*; Fujikawa, Takashi*
Photon Factory News, 29(1), p.20 - 25, 2011/05
no abstracts in English
Kawamura, Yoshinori; Onishi, Yoshihiro*; Okuno, Kenji*; Yamanishi, Toshihiko
Fusion Engineering and Design, 83(10-12), p.1384 - 1387, 2008/12
Times Cited Count：14 Percentile：66.71(Nuclear Science & Technology)A gas chromatograph using a cryogenic separation column is one of the methods for hydrogen isotope analysis. However, use of liquid nitrogen is a cause of long analysis time and is not suitable for easy installation. The development of the column material having separation capability at comparatively high temperature is one of the solutions for these weak points. Mordenite (MOR) is a kind of the synthesis zeolite, and it has been reported that the separation column using MOR has possibility to separate hydrogen isotope mixture at comparatively high temperature. In this work, the separation columns using MOR were made and tested. The peaks of H and D were mostly separated at 144 K, but they were not separated at 195 K. MOR column adjusted in this work was still not for the practical use. However, this result suggests the possibility of the existence of the synthesis zeolite that can separate hydrogen isotope mixture at comparatively high temperature.
Okamura, Masachika*; Shimizu, Akira*; Onishi, Noboru*; Hase, Yoshihiro; Yoshihara, Ryohei; Narumi, Issei
JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 62, 2008/11
no abstracts in English
Kawamura, Yoshinori; Onishi, Yoshihiro*; Okuno, Kenji*; Yamanishi, Toshihiko
Fusion Engineering and Design, 83(4), p.655 - 660, 2008/05
Times Cited Count：13 Percentile：64.63(Nuclear Science & Technology)In a fusion reactor system, a monitoring of hydrogen isotopes including tritium is necessary from the viewpoint of safety control. A gas chromatography using a cryogenic separation column is one of the methods for hydrogen isotope analysis. However, use of a refrigerant such as liquid nitrogen is a cause of long analysis time and is not suitable for easy installation. The development of the column material having separation capability at fairly high temperature is one of the solutions for these weak points. Synthesis zeolite such as molecular sieve 5A is a probable candidate. If the factor effected to the hydrogen adsorption property of the synthesis zeolite is clarified, it may lead to the development of the new zeolite optimized to the separation column. So, in this work, adsorption isotherms of hydrogen and deuterium for mordenite were investigated. The amount of adsorption per unit weight was larger than that of molecular sieve 5A.
Takahashi, Yoshihiro*; Oki, Takahiro*; Nagasawa, Takaharu*; Nakajima, Yasuhito*; Kawanabe, Ryu*; Onishi, Kazunori*; Hirao, Toshio; Onoda, Shinobu; Mishima, Kenta; Kawano, Katsuyasu*; et al.
Nuclear Instruments and Methods in Physics Research B, 260(1), p.309 - 313, 2007/07
Times Cited Count：4 Percentile：35.71(Instruments & Instrumentation)no abstracts in English
Shibahara, Takahiro*; Tanabe, Tetsuo*; Hirohata, Yuko*; Oya, Yasuhisa*; Oyaizu, Makoto*; Yoshikawa, Akira*; Onishi, Yoshihiro*; Arai, Takashi; Masaki, Kei; Okuno, Kenji*; et al.
Journal of Nuclear Materials, 357(1-3), p.115 - 125, 2006/10
Times Cited Count：20 Percentile：78.83(Materials Science, Multidisciplinary)no abstracts in English
Shibahara, Takahiro*; Tanabe, Tetsuo*; Hirohata, Yuko*; Oya, Yasuhisa*; Oyaizu, Makoto*; Yoshikawa, Akira*; Onishi, Yoshihiro*; Arai, Takashi; Masaki, Kei; Okuno, Kenji*; et al.
Nuclear Fusion, 46(10), p.841 - 847, 2006/10
Times Cited Count：18 Percentile：52.46(Physics, Fluids & Plasmas)no abstracts in English
m fully depleted CMOS/SOI digital logic devicesMakihara, Akiko*; Asai, Hiroaki*; Tsuchiya, Yoshihisa*; Amano, Yukio*; Midorikawa, Masahiko*; Shindo, Hiroyuki*; Kuboyama, Satoshi*; Onoda, Shinobu; Hirao, Toshio; Nakajima, Yasuhito*; et al.
Proceedings of 7th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-7), p.95 - 98, 2006/10
no abstracts in English
Nishikino, Masaharu; Tanaka, Momoko; Kawazome, Hayato; Kawachi, Tetsuya; Sasaki, Akira; Hasegawa, Noboru; Ochi, Yoshihiro; Kishimoto, Maki; Nagashima, Keisuke; Onishi, Naofumi*
AIP Conference Proceedings 827, p.499 - 504, 2006/04
no abstracts in English
