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Nomoto, Yasunobu; Mizuta, Naoki; Morita, Keisuke; Aoki, Takeshi; Okita, Shoichiro; Ishii, Katsunori; Kurahayashi, Kaoru; Yasuda, Takanori; Tanaka, Masato; Isaka, Kazuyoshi; et al.
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 7 Pages, 2023/05
Mizuta, Naoki; Morita, Keisuke; Aoki, Takeshi; Okita, Shoichiro; Ishii, Katsunori; Kurahayashi, Kaoru; Yasuda, Takanori; Tanaka, Masato; Isaka, Kazuyoshi; Noguchi, Hiroki; et al.
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 6 Pages, 2023/05
Kobayashi, Daisuke; Yamamoto, Masahiko; Nishida, Naoki; Miyoshi, Ryuta; Nemoto, Ryo*; Hayashi, Hiroyuki*; Kato, Keisuke; Nishino, Saki; Kuno, Takehiko; Kitao, Takahiko; et al.
Nihon Hozen Gakkai Dai-18-Kai Gakujutsu Koenkai Yoshishu, p.237 - 240, 2022/07
All gloves attached to glove-box in Tokai Reprocessing Plant have a fixed expiration date and have to be replaced every 4-year. However, degrees of glove deterioration are different depending on its usage environment (frequency, chemicals, radiation, etc.), because of rubber products. Therefore, physical properties such as tensile strength, elongation, hardness of gloves are measured, and the life-time of gloves are estimated. As a result, gloves without any defects in its appearance have enough physical property for acceptance criteria of new glove. The extrapolated physical property of glove is sufficiently larger than the reported values of damaged glove. No deterioration in physical properties of gloves, that are periodically replaced without any defects in its appearance, is observed and the usable life-time of the glove is estimated to be 8 years.
Muramatsu, Haruka*; Hayashi, Tasuku*; Yuasa, Naoki*; Konno, Ryohei*; Yamaguchi, Atsushi*; Mitsuda, Kazuhisa*; Yamasaki, Noriko*; Maehata, Keisuke*; Kikunaga, Hidetoshi*; Takimoto, Misaki; et al.
Journal of Low Temperature Physics, 200(5-6), p.452 - 460, 2020/09
Times Cited Count:1 Percentile:6.04(Physics, Applied)Tsuji, Hideki*; Ishii, Yumiko*; Shin, M.*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Kurihara, Momo*; Yasutaka, Tetsuo*; Kuramoto, Takayuki*; Nakanishi, Takahiro; Lee, S*; et al.
Science of the Total Environment, 697, p.134093_1 - 134093_11, 2019/12
Times Cited Count:17 Percentile:59.38(Environmental Sciences)To investigate the main factors that control the dissolved radiocesium concentration in river water in the area affected by the Fukushima Daiichi Nuclear Power Plant accident, the correlations between the dissolved Cs concentrations at 66 sites normalized to the average Cs inventories for the watersheds with the land use, soil components, topography, and water quality factors were assessed. We found that the topographic wetness index is significantly and positively correlated with the normalized dissolved Cs concentration. Similar positive correlations have been found for European rivers because wetland areas with boggy organic soils that weakly retain Cs are mainly found on plains. However, for small Japanese river watersheds, the building area ratio in the watershed strongly affected the dissolved Cs concentration.
Kurihara, Momo*; Yasutaka, Tetsuo*; Aono, Tatsuo*; Ashikawa, Nobuo*; Ebina, Hiroyuki*; Iijima, Takeshi*; Ishimaru, Kei*; Kanai, Ramon*; Karube, Jinichi*; Konnai, Yae*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 322(2), p.477 - 485, 2019/11
Times Cited Count:2 Percentile:21.58(Chemistry, Analytical)We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the Cs results were within 2, indicating that the methods were accurate. The relative standard deviations (RSDs) indicating the variability in the results from different laboratories were larger than the RSDs indicating the variability in the results from each separate laboratory.
Yamaguchi, Atsushi*; Muramatsu, Haruka*; Hayashi, Tasuku*; Yuasa, Naoki*; Nakamura, Keisuke; Takimoto, Misaki; Haba, Hiromitsu*; Konashi, Kenji*; Watanabe, Makoto*; Kikunaga, Hidetoshi*; et al.
Physical Review Letters, 123(22), p.222501_1 - 222501_6, 2019/11
Times Cited Count:36 Percentile:89.11(Physics, Multidisciplinary)Hayashi, Kentaro*; Katayanagi, Nobuko*; Fumoto, Tamon*; Hasegawa, Toshihiro*; Ono, Keisuke*; Katata, Genki
Nogyo Kankyo Gijutsu Kenkyojo Heisei 25 Nendo Kenkyu Seika Joho, 30 (Internet), 2 Pages, 2014/03
no abstracts in English
Katata, Genki; Hayashi, Kentaro*; Ono, Keisuke*; Nagai, Haruyasu; Miyata, Akira*; Mano, Masayoshi*
Agricultural and Forest Meteorology, 180, p.1 - 21, 2013/10
Times Cited Count:19 Percentile:65.81(Agronomy)A multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) was modified to calculate the NH exchange fluxes over a paddy field. The heat transfer at the paddy water layer and the dry deposition of water-soluble gases such as NH and SO onto the wet canopy, as well as the emission potentials of NH from the rice foliage and the surface of floodwater or soil were incorporated into the model. The modified model reproduced the observed surface and NH fluxes, paddy water temperature, and soil temperature and moisture during both the fallow and cropping seasons. The "recaptured fraction" was defined as the ratio of the amount of volatilized NH recaptured by the foliage to the total amount. Numerical experiments using the modified model with varying emission potentials of NH showed that the recaptured fraction increased with an increase in the leaf area index (LAI) and saturated when LAI 1 because of the limitation of stomatal uptake.
Kiriyama, Hiromitsu; Shimomura, Takuya; Mori, Michiaki; Nakai, Yoshiki*; Tanoue, Manabu; Kondo, Shuji; Kanazawa, Shuhei; Pirozhkov, A. S.; Esirkepov, T. Z.; Hayashi, Yukio; et al.
Applied Sciences (Internet), 3(1), p.214 - 250, 2013/03
Times Cited Count:15 Percentile:50(Chemistry, Multidisciplinary)This paper reviews techniques for improving the temporal contrast and spatial beam quality in an ultra-intense laser system that is based on chirped-pulse amplification (CPA). We describe the design, performance, and characterization of our laser system, which has the potential for achieving a peak power of 600 TW. We also describe applications of the laser system in the relativistically dominant regime of laser-matter interactions and discuss a compact, high efficiency diode-pumped laser system.
Mori, Michiaki; Kando, Masaki; Kotaki, Hideyuki; Hayashi, Yukio; Bulanov, S. V.; Koga, J. K.; Kondo, Kiminori; Pirozhkov, A. S.; Nishimura, Hiroaki*; Nagashima, Keisuke
Journal of the Physical Society of Japan, 80(10), p.105001_1 - 105001_2, 2011/09
Times Cited Count:4 Percentile:33.73(Physics, Multidisciplinary)The effects of plasma density and laser power on the energetic electron bunch generation in an Argon (high-Z) gas-jet target in the self modulated laser wakefield acceleration regime were investigated. A vector potential threshold for electron injection was obtained 2.8 through a simple analytical model include two-dimensional laser pulse compression by relativistic self-focusing, and it is similar to that after accounting for three-dimensional laser pulse compression in the standard Laser Wakefield acceleration regime.
Kobayashi, Takuya; Togawa, Orihiko; Ito, Toshimichi; Otosaka, Shigeyoshi; Kawamura, Hideyuki; Hayashi, Keisuke*; Shima, Shigeki*; Nakayama, Tomoharu*; In, Teiji*
JAEA-Research 2009-040, 63 Pages, 2009/12
A spent nuclear fuel reprocessing plant has the possibility of routine releases of liquid radioactive wastes from a discharge pipe to the off Shimokita region during its operations. Thus, for environmental safety, it is important to assess the migration processes of released radionuclides from the plant. Therefore, an ocean circulation prediction code and an oceanic radionuclides migration prediction code, which were developed by Japan Atomic Energy Agency, has been improved to describe the migration behavior of radionuclides in the off Shimokita region. Parameters on characteristics and dynamics of particulate materials in seawater have also been obtained in the study area for the adjustment and verification of the oceanic radionuclides migration prediction code. This report summarizes the primary results of the study which was carried out at the off Shimokita region from FY2003 to 2008.
Iwatsuki, Teruki; Sato, Haruo; Tanai, Kenji; Inagaki, Manabu; Sawada, Atsushi; Niinuma, Hiroaki; Ishii, Eiichi; Maekawa, Keisuke; Tomura, Goji; Sanada, Hiroyuki; et al.
JAEA-Research 2009-002, 156 Pages, 2009/05
The research and development plan for geological investigation, engineering technology and safety assessment during the drilling of a shaft down to intermediate depth are summarized according to the Midterm Plan till 2009 Fiscal year of JAEA. This report describes subject, current status and programme in the "Phase 2: Construction phase" (investigations during construction of the underground facilities). Furthermore regarding R&D plan in next Midterm Plan of JAEA, preliminary ideas are summarized.
Kobayashi, Takuya; Otosaka, Shigeyoshi; Togawa, Orihiko; Hayashi, Keisuke
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.51 - 57, 2007/03
An ocean environment assessment system that forecasts the detailed migration processes of radionuclides in the ocean has been developed. This system consists of an ocean current model and a particle random-walk model. The ocean current model is the modified Princeton Ocean Model (POM). The POM calculates tidal currents by giving tide levels at the open boundary. The particle random-walk model, SEA-GEARN, calculates the radionuclides migration in the ocean. Radionuclides that exist in the ocean are modeled in three phases, such as dissolved in seawater, adsorbed with suspended solids and adsorbed with active bottom sediment. As model validation, the system has been applied to the Irish Sea to simulate the long-term dispersion of Cs actually released from the BNFL spent nuclear fuel reprocessing plant at Sellafield in UK. The calculation well reproduces the main characteristic of migration of dissolved surface Cs concentration in the Irish Sea.
Kobayashi, Takuya; Otosaka, Shigeyoshi; Togawa, Orihiko; Hayashi, Keisuke
Journal of Nuclear Science and Technology, 44(2), p.238 - 247, 2007/02
Times Cited Count:36 Percentile:90.33(Nuclear Science & Technology)A numerical simulation model system that consists of an ocean current model, Princeton Ocean Model (POM), and a particle random-walk model, SEA-GEARN, has been developed to describe the non-conservative radionuclide migration behavior in a shallow water region. Radionuclides that exist in the ocean are modeled in three phases, such as dissolved in seawater, adsorbed with suspended solids and adsorbed with active bottom sediment. The adsorption and desorption processes between the dissolved and solid phases are solved with the kinetic transfer coefficients by the stochastic method. Deposition of suspended solids and resuspension of bottom sediment are also considered. The system has been applied to simulate the long-term dispersion of Cs actually released from the BNFL spent nuclear fuel reprocessing plant at Sellafield in UK. The calculation well reproduces the main characteristic of migration of dissolved Cs concentration in the Irish Sea.
Minakawa, Nobuaki; Moriai, Atsushi; Saito, Toru; Tanaka, Keisuke*; Akiniwa, Yoshiaki*; Hayashi, Makoto*; Okido, Shinobu*
Nihon Zairyo Gakkai Dai-36-Kai X Sen Zairyo Kyodo Ni Kansuru Shimpojiumu Koen Rombunshu, p.263 - 265, 2000/09
no abstracts in English
Akiniwa, Yoshiaki*; Tanaka, Keisuke*; *; Hayashi, Makoto*; Morii, Yukio; Minakawa, Nobuaki
Zairyo, 47(7), p.755 - 761, 1998/07
no abstracts in English
Miya, Naoyuki; Kikuchi, Mitsuru; Ushigusa, Kenkichi; ; Nagashima, Keisuke; Neyatani, Yuzuru; Tobita, Kenji; ; Masaki, Kei; Kaminaga, Atsushi; et al.
JAERI-Research 98-012, 222 Pages, 1998/03
no abstracts in English
; Ushigusa, Kenkichi; Kikuchi, Mitsuru; Nagashima, Keisuke; Neyatani, Yuzuru; Miya, Naoyuki; ; Takahashi, Yoshikazu; Hayashi, Takumi; Kuriyama, Masaaki; et al.
Proceedings of 17th IEEE/NPSS Symposium Fusion Engineering (SOFE'97), 1, p.233 - 236, 1998/00
no abstracts in English
Kikuchi, Mitsuru; ; ; Miya, Naoyuki; Ushigusa, Kenkichi; Nagashima, Keisuke; Aoyagi, Tetsuo; ; Neyatani, Yuzuru; Naito, Osamu; et al.
JAERI-Research 97-026, 70 Pages, 1997/03
no abstracts in English