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Toyomori, Yuka*; Tsuji, Satoru*; Mitsuda, Shinobu*; Okayama, Yoichi*; Ashida, Shiomi*; Mori, Atsunori*; Kobayashi, Toru; Miyazaki, Yuji; Yaita, Tsuyoshi; Arae, Sachie*; et al.
Bulletin of the Chemical Society of Japan, 89(12), p.1480 - 1486, 2016/09
Times Cited Count：8 Percentile：29.47(Chemistry, Multidisciplinary)
As using high-resolution inelastic X-ray scatteringMurai, Naoki*; Fukuda, Tatsuo; Kobayashi, Tatsuya*; Nakajima, Masamichi*; Uchiyama, Hiroshi*; Ishikawa, Daisuke*; Tsutsui, Satoshi*; Nakamura, Hiroki; Machida, Masahiko; Miyasaka, Shigeki*; et al.
Physical Review B, 93(2), p.020301_1 - 020301_5, 2016/01
Times Cited Count：7 Percentile：34.12(Materials Science, Multidisciplinary)Katata, Genki; Chino, Masamichi; Kobayashi, Takuya; Terada, Hiroaki; Ota, Masakazu; Nagai, Haruyasu; Kajino, Mizuo*; Draxler, R.*; Hort, M.*; Malo, A.*; et al.
Atmospheric Chemistry and Physics, 15(2), p.1029 - 1070, 2015/01
Times Cited Count：220 Percentile：98.87(Environmental Sciences)We estimated a detailed time trend of atmospheric releases during the Fukushima Dai-ichi Power Station (FNPS1) accident by combining environmental monitoring data with coupling simulation of atmospheric model of WSPEEDI-II, and oceanic dispersion model of SEA-GEARN-FDM. The new scheme of dry and fogwater depositions, in-cloud scavenging, cloud condensation nuclei activity, and wet scavenging by ice phase for radioactive iodine gas and other particles was incorporated into WSPEEDI-II. The results revealed that the major releases of radionuclides occurred in the following periods: afternoon on 12 March when the wet venting and hydrogen explosion at Unit 1, morning on 13 March after the venting event at Unit 3, midnight on 14 March when three-time openings of SRV were conducted at Unit 2, morning and night on 15 March, and morning on 16 March.
C discharge at RI facilities; A Comparison of collection and oxidation methodsUeno, Yumi; Koarashi, Jun; Iwai, Yasunori; Sato, Junya; Takahashi, Teruhiko; Sawahata, Katsunori; Sekita, Tsutomu; Kobayashi, Makoto; Tsunoda, Masahiko; Kikuchi, Masamitsu
Hoken Butsuri, 49(1), p.39 - 44, 2014/03
The Japan Atomic Energy Agency has conducted a monthly monitoring of airborne C discharge at the forth research building (RI facility) of the Tokai Research and Development Center. In the current monitoring, C, which exists in various chemical forms in airborne effluent, is converted into CO
with CuO catalyst and then collected using monoethanolamine (MEA) as CO absorbent. However, this collection method has some issues on safety management because the CuO catalyst requires a high heating temperature (600
C) to ensure a high oxidation efficiency and the MEA is specified as a poisonous and deleterious substance. To establish a safer, manageable and reliable method for monitoring airborne C discharge, we examined collection methods that use different CO absorbents (MEA and Carbo-Sorb E) and oxidation catalysts (CuO, Pt/Alumina and Pd/ZrO). The results showed 100% CO collection efficiency of MEA during a 30-day sampling period under the condition tested. In contrast, Carbo-Sorb E was found to be unsuitable for the monthly-long CO collection because of its high volatile nature. Among the oxidation catalysts, the Pd/ZrO showed the highest oxidation efficiency for CH
at a lower temperature.
Kobayashi, Takuya; Nagai, Haruyasu; Chino, Masamichi; Kawamura, Hideyuki
Journal of Nuclear Science and Technology, 50(3), p.255 - 264, 2013/03
Times Cited Count：139 Percentile：99.72(Nuclear Science & Technology)The source term of the atmospheric release of 
I and 
Cs due to the Fukushima Dai-ichi Nuclear Power Plant accident estimated by previous studies was validated and refined by coupling atmospheric and oceanic dispersion simulations with observed 
Cs in seawater collected from the Pacific Ocean. By assuming the same release rate for Cs and Cs, the sea surface concentration of Cs was calculated using the previously estimated source term and was compared with measurement data. The release rate of Cs was refined to reduce underestimation of measurements, which resulted in a larger value than that previously estimated. In addition, the release rate of I was refined to follow the radioactivity ratio of Cs. As a result, the total amounts of I and Cs discharged into the atmosphere from 5 JST on March 12 to 0 JST on March 20 were estimated to be approximately 2.0
10
and 1.310
Bq, respectively.
Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Terakado, Masayuki; Sawahata, Masayuki; Suzuki, Sadaaki; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Hiranai, Shinichi; et al.
Nuclear Fusion, 49(8), p.085001_1 - 085001_7, 2009/07
Times Cited Count：21 Percentile：61.72(Physics, Fluids & Plasmas)In the gyrotron development in JT-60U ECRF system, output power of 1.5 MW for 1 s has been achieved at 110 GHz. It is the world highest power oscillation 
1 s. In addition to the carefully designed cavity and collector in view of thermal stress, an RF shield for the adjustment bellows, and a low-dielectric-loss DC break enabled this achievement. Power modulation technique by anode voltage control was improved to obtain high modulation frequency and 5 kHz has been achieved for NTM stabilizing experiments. Long pulse demonstration of 0.4 MW, 30 s injection to the plasma has been achieved with real time control of anode/cathode-heater. It has been confirmed that the temperature of cooled components were saturated and no evidence of damage were found. An innovative antenna having wide range of beam steering capability with linearly-moving-mirror concept has been designed for long pulse. Beam profile and mechanical strength analyses shows the feasibility of the antenna.
Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Terakado, Masayuki; Sawahata, Masayuki; Suzuki, Sadaaki; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Hiranai, Shinichi; et al.
Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10
In the gyrotron development in JT-60U ECRF system, output power of 1.5 MW for 1 s has been achieved at 110 GHz. It is the world highest power oscillation 1 s. In addition to the carefully designed cavity and collector in view of thermal stress, an RF shield for the adjustment bellows, and a low-dielectric-loss DC break enabled this achievement. Power modulation technique by anode voltage control was improved to obtain high modulation frequency and 5 kHz has been achieved for NTM stabilizing experiments. Long pulse demonstration of 0.4 MW, 30 s injection to the plasma has been achieved with real time control of anode/cathode-heater. It has been confirmed that the temperature of cooled components were saturated and no evidence of damage were found. An innovative antenna having wide range of beam steering capability with linearly-moving-mirror concept has been designed for long pulse. Beam profile and mechanical strength analyses shows the feasibility of the antenna.
Kobayashi, Takayuki; Moriyama, Shinichi; Seki, Masami; Sawahata, Masayuki; Terakado, Masayuki; Fujii, Tsuneyuki
Plasma and Fusion Research (Internet), 3, p.014_1 - 014_3, 2008/03
Gyrotrons are used for electron cyclotron heating (ECH) / current drive (ECCD) as high power millimeter wave sources in high performance plasma experiments. Pulse length from 0.1 to several seconds with high power is required in present tokamak experiments, such as JT-60U. However, 0.1 s oscillation had only been achieved in the power level of 1.5 MW. In JAEA, high power and long pulse oscillation experiments by using the latest JT-60U gyrotron have been tried to achieve power level of 1.5 MW and pulse length over 1 s. As a result, 1.5 MW/1 s oscillation has been successfully achieved by the fine optimization of operation parameters. In this paper, the first results of the oscillation experiment of 1.5 MW for 1 s and future plans of gyrotron improvements are described.
Ezure, Toshiki; Kimura, Nobuyuki; Kobayashi, Jun; Ito, Masami*; Kamide, Hideki
JAEA-Research 2006-067, 35 Pages, 2006/10
JAEA-Research-2006-067.pdf:7.49MB
A sodium cooled reactor has been investigated in the feasibility study of FBR cycle. In the study, a compact reactor vessel was designed, and the cover gas entrainment (GE) at the free surface is one of the significant issues. It is required to clarify the criterion of GE at free surface. GE at the free surface could be categorized into following three types, wave break, submerged flow, surface vortex. However, there was no clear quantitative evaluation method and criteria regarding the onset condition of GE by the surface vortex. In the present study, some experiments were performed focusing on the transient phenomena of GE by surface vortex. The relationship between circulation and length of gas core were measured by the particle image velocimetry and visualization. From the results of this study, the relationship between gas core length and probability of GE was clarified, and time-delay between the increase of circulation and the increase of gas core was found.
Nagai, Haruyasu; Chino, Masamichi; Terada, Hiroaki; Harayama, Takaya*; Kobayashi, Takuya; Tsuzuki, Katsunori; Kim, K.; Furuno, Akiko
JAEA-Research 2006-057, 67 Pages, 2006/09
JAEA-Research-2006-057.pdf:13.49MB
A numerical simulation system SPEEDI-MP has been developed to apply for various environmental studies. SPEEDI-MP consists of dynamical models and material transport models for the atmospheric, terrestrial, and oceanic environments, database for model inputs, and system utilities for file management, visualization, etc. As a numerical simulation tool, a model coupling program (model coupler) has been developed. A coupled model system for water circulation has been constructed with atmosphere, ocean, wave, hydrology, and land-surface models using the model coupler. System utility GUIs are based on the Web technology, allowing users to manipulate all the functions on the system using their own PCs via the internet. In this system, the source estimation function in the atmospheric transport model can be executed on the grid computer system. Performance tests of the coupled model system for water circulation were also carried out for the flood and the storm surge events.
Kobayashi, Takuya; Chino, Masamichi; Togawa, Orihiko
Journal of Nuclear Science and Technology, 43(5), p.569 - 575, 2006/05
Times Cited Count：3 Percentile：24.11(Nuclear Science & Technology)A dissolved radionuclide migration code system that consists of a ocean circulation model, Princeton Ocean Model, and a particle random-walk model, SEA-GEARN, has been developed. The oceanic migration of Cs discharged from a nuclear submarine in a hypothetical accident at the Tsushima Strait was calculated in the southwestern area of the Japan Sea as a model application. The calculations for instantaneous releases every 10 days were carried out for one year to study the seasonal differences of migration process of the dissolved radionuclides. The migration tendencies of dissolved radionuclides were divided into two patterns. For the releases started from January to September, all of the high concentration areas migrated to the northeast along the coastline of the Main Island of Japan from the release point. As for the releases from October to December, some high concentrations areas migrated to the west from the release point and the concentrations of Cs along the coastline of the Main Island of Japan were comparatively low.
Kimura, Nobuyuki; Tobita, Akira; Kobayashi, Jun; Nakayama, Oukatsu; Ito, Masami*; Kamide, Hideki
JNC TN9400 2004-067, 48 Pages, 2004/05
JNC-TN9400-2004-067.pdf:19.55MB
An innovative sodium cooled fast reactor has been investigated in a frame work of the FBR feasibility study. A compact reactor vessel is designed to reduce the construction cost, where sodium flow velocity increases. One of the thermal hydraulic issues in this design is gas entrainment at free surface in the reactor vessel. Dipped plates (D/P) are set below the free surface in order to prevent the gas entrainment.We performed an 1/10th scaled model water experiment for the upper plenum of reactor vessel and flow optimization was done to reduce flow velocity near the free surface. However, previous studies showed that the gas entrainment depends on model scale. Then an 1/1.8th scaled model was also planned to confirm the phenomena in an enough large model. As a test section, 90 degree sector and region between the free surface and the D/P was modeled by 1/1.8th scale. Boundary conditions at D/P gaps and radial cross sections of sector ends were obtained by the 1/10th scaled full sector model. The gas entrainment was not observed in the model under the velocity condition of reactor full power operation at water levels higher than 4% of the normal height from the D/P. It is shown that the gas entrainment will be eliminated in the reactor vessel according to the current design approach.
Kikuchi, Masamitsu; Taki, Mitsumasa; Kume, Etsuo; Kobayashi, Hideo*; Yamada, Toshio*; Yamaguchi, Takenori
JAERI-Data/Code 2004-006, 146 Pages, 2004/03
JAERI-Data-Code-2004-006.pdf:6.87MB
The nuclear facilities, which are required to control the released radioactive gases and liquid, exist in Tokai research establishment as much as 40. These radioactive controls are carried out complying with the statutes in each facility. The released radioactivity data of each facility must be reported to MEXT and Ibaraki Prefecture from Tokai Research Establishment. This system is developed to make the database gathering the radioactivity data of each facilities for unitary control as Tokai Research Establishment and contribute to make the reports to MEXT and Ibaraki Prefecture.
Taki, Mitsumasa; Kikuchi, Masamitsu; Kobayashi, Hideo*; Yamaguchi, Takenori
JAERI-Data/Code 2003-006, 99 Pages, 2003/05
JAERI-Data-Code-2003-006.pdf:6.97MB
A computer code (EDAS) was developed to assess the public dose for the safety assessment to get the license of nuclear reactor operation. This code system is used for the safety analysis of public around the nuclear reactor in case of normal operation and severe accident. This code was revised and composed for personal computer user according to the Nuclear Safety Guidelines reflected the ICRP1990 recommendation. These guidelines are revised by Nuclear Safety Commission on March, 2001, which are “Weather analysis guideline for the safety assessment of nuclear power reactor", “ Public dose around the facility assessment guideline corresponding to the objective value for nuclear power light water reactor" and “Public dose assessment guideline for safety review of nuclear power light water reactor". This code has been already opened for public user by JAERI, and English version code and user manual are prepared moreover. This English version code is helpful for international cooperation concerning the nuclear safety assessment with JAERI.
Suzuki, Yoshio; Matsumoto, Nobuko*; Yamagishi, Nobuhiro*; Higuchi, Kenji; Otani, Takayuki; Nagai, Haruyasu; Terada, Hiroaki; Furuno, Akiko; Chino, Masamichi; Kobayashi, Takuya
Computational Science - ICCS 2003, International Conference Saint Petersburg Russian Federation, Melbourne Australia, June 2-4, 2003 Proceedings, p.120 - 129, 2003/00
Information-Technology Based Laboratory (ITBL) project has been propelled as one of e-Japan priority policy programs. The purposes of the project are to share intellectual resources such as remote computers, programs and data in universities and institutes and to support cooperative studies among researchers, building a virtual research environment, ITBL. Japan Atomic Energy Research Institute (JAERI) has been working on installation and management of hardware and development of infrastructure software and applications. As application software, researches on quantum bioinformatics and environmental sciences are carried out. This paper presents utilization of ITBL system infra-structure software for 'Numerical Environment System' which is developed for environmental studies. More effective job executions and visualization are ex-pected by using Task Mapping Editor (TME) and AVS/ITBL, which are tools developed as infrastructure software.
Kobayashi, Takuya; Nagai, Haruyasu; Chino, Masamichi; Togawa, Orihiko
Proceedings of International Symposium on Radioecology and Environmental Dosimetry, p.500 - 504, 2003/00
The possibility of radionuclide release to the environment is on the increase due to a growth of nuclear facilities in Asia, military problems, nuclear terrorism, etc. The released radionuclides circulate among the atmospheric, oceanic and terrestrial environment, influencing human and natural environment through complex processes. In order to reduce the damage from these pollutants, it is necessary to estimate their migration behavior in detail. A software system SPEEDI-MP (SPEEDI Multi-model Package) is under development to resolve such environmental problems by simulating the 'inclusive and successive' behavior of pollutants in the atmospheric, oceanic and terrestrial environment. As code verification, the system has been applied to a hypothetical accident of a nuclear submarine if it sinks in an offshore region around Japan. The predicted results are examined, and the applicability and validity of the system are discussed.
Kobayashi, Takuya; Lee, S.; Chino, Masamichi
Journal of Nuclear Science and Technology, 39(2), p.171 - 179, 2002/02
Times Cited Count：3 Percentile：23.41(Nuclear Science & Technology)A three-dimensional model system was developed to predict oceanic dispersions of radionuclides released into the eastern area of Shimokita Peninsula. This system is a combination of the Princeton Ocean Model (POM) for predicting ocean currents and a particle random walk model for oceanic dispersion of radionuclides. The model was verified by using measured currents, temperature and salinity at the coastal area of Shimokita, Aomori-ken, Japan, where a nuclear fuel reprocessing plant is under construction. The results obtained from simulations area as follows; (1) Wind and the Tsugaru Warm Current entering into the objective region through the Tsugaru Strait significantly affect the structure of current over the region. (2) POM can represent seasonal variations of the Tsugaru Warm Current well with hypothetical oceanographic data. The calculation succeeded to reproduce the coastal mode from winter to spring and the gyre mode from summer to autumn.
Ise, Hideo*; Izaki, Makoto*; Oishi, Haruo*; Mori, Seiji*; Ako, Kentaro*; Moriyama, Hisashi*; Kagaya, Hiroaki*; Kobayashi, Masami*; Taguchi, Ko*; Shibanuma, Kiyoshi
FAPIG, (159), p.10 - 14, 2001/11
no abstracts in English
U and 
Fe M
ssbauer spectroscopic study of UFeTsutsui, Satoshi; Nakada, Masami; Kobayashi, Yasuhiro*; Nasu, Saburo*; Haga, Yoshinori; Onuki, Yoshichika
Hyperfine Interactions, 133(1-4), p.17 - 21, 2001/11
no abstracts in English
Kobayashi, Takuya; Lee, S.; Chino, Masamichi
Proceedings of 4th International Conference on Supercomputing in Nuclear Applications (SNA 2000) (CD-ROM), 9 Pages, 2000/09
no abstracts in English
