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Sano, Naruto; Yamashita, Naoki; Watanabe, Masaya; Tsukada, Manabu*; Hoshino, Kazutoyo*; Hirai, Koki; Ikegami, Yuta*; Tashiro, Shinsuke; Yoshida, Ryoichiro; Hatakeyama, Yuichi; et al.
JAEA-Technology 2023-029, 36 Pages, 2024/03
JAEA-Technology-2023-029.pdf:2.47MB
At the Waste Safety Testing Facility (WASTEF), the gamma ray irradiation device "Gamma Cell 220" was relocated from the 4th Research Building of the Nuclear Science Research Institute in FY2019, and the use of gamma ray irradiation has begun. Initially, Fuel Cycle Safety Research Group, Fuel Cycle Safety Research Division, Nuclear Safety Research Center, Sector of Nuclear Safety Research and Emergency Preparedness, the owner of this device, conducted the tests as the main user, but since 2022, other users, including those outside the organization, have started using it. The gamma ray irradiation device "Gamma Cell 220" is manufactured by Nordion International Inc. in Canada. Since it was purchased in 1989, the built-in 
Co radiation source has been updated once, and safety research related to nuclear fuel cycles, etc. It is still used for this purpose to this day. This report summarizes the equipment overview of the gamma ray irradiation device "Gamma Cell 220", its permits and licenses at WASTEF, usage status, maintenance and inspection, and future prospects.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count：66 Percentile：94.76(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 
C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
)Komatsu, Kazuki*; Iwasaki, Tsugumi*; Murata, Kosuke*; Yamashiro, Hideaki*; Goh, V. S. T.*; Nakayama, Ryo*; Fujishima, Yohei*; Ono, Takumi*; Kino, Yasushi*; Shimizu, Yoshinaka*; et al.
Reproduction in Domestic Animals, 56(3), p.484 - 497, 2021/03
Times Cited Count：16 Percentile：83.06(Agriculture, Dairy & Animal Science)We have established an archive system of livestock and wild animals from the surrounding ex-evacuation zone. Wildlife within the alert zone have been exposed to low-dose-rate (LDR) radiation for a long and continuous time. In this study, we analysed the morphological characteristics of the testes and in vitro fertilization (IVF) capacity of cryopreserved sperm of raccoons from the ex-evacuation zone of the FDNPP accident. This study revealed that the chronic and LDR radiation exposure associated with the FDNPP accident had no adverse effect on the reproductive characteristics and functions of male raccoons.
scattering length from 
photoproduction on the proton near the reaction thresholdIshikawa, 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：8 Percentile：49.51(Physics, Nuclear)Sukegawa, Atsuhiko; Murakami, Haruyuki; Matsunaga, Go; Sakurai, Shinji; Takechi, Manabu; Yoshida, Kiyoshi; Ikeda, Yoshitaka
Fusion Engineering and Design, 98-99, p.2076 - 2079, 2015/10
Times Cited Count：3 Percentile：21.86(Nuclear Science & Technology)The JT-60SA project is a EU - JA satellite tokamak under Broader Approach in support of the ITER project. In-vessel coils are designed and assembled by JA. The resin-insulator is required to have a heat resistance against the baking temperature of vacuum vessel of 
200C (40000 hour). Thus the assessment of the heat load is fundamental for the design of the coils. However, the estimation of the lifetime of resin-insulator under the high-temperature region has not been examined. In the present study, the estimation of the lifetime of seven candidate resin-insulators such as epoxy resin and cyanate-ester resin under the 220C temperature region have been performed for the current coils design. Weight reduction of the seven candidate insulators was measured at different heating times under 180C, 200C and 220C environment using three thermostatic ovens, respectively. The reduction of the insulators has been used as input for Weibull-analysis towards Arrhenius-plot. Lifetime of the resins has been estimated for the first time at the high temperature region by the plot. Lifetime of the resin-insulators have been evaluated and discussed as well as the available temperature of the in-vessel coils.
Wakai, Takashi; Machida, Hideo*; Arakawa, Manabu*; Yoshida, Shinji*; Enuma, Yasuhiro
Journal of Pressure Vessel Technology, 135(1), p.011401_1 - 011401_9, 2013/02
Times Cited Count：3 Percentile：16.70(Engineering, Mechanical)This was carried out to establish crack opening displacement (COD) evaluation methods used in Leak-Before-Break (LBB) assessment of sodium pipes of the Japan Sodium cooled Fast Reactor (JSFR). A COD assessment method applicable to thin walled large diameter pipe made of modified 9Cr-1Mo steel was proposed in this study. In this method, COD was calculated by classifying the components of COD; elastic, local plastic and fully plastic. In addition, the verification of this method was performed by comparing with the results of a series of four-point bending tests at elevated temperature using thin wall modified 9Cr-1Mo steel pipe containing a circumferential through wall crack. The rational leak rate evaluation method in LBB assessment was proposed.
Litaudon, X.*; Sakamoto, Yoshiteru; de Vries, P. C.*; Salmi, A.*; Tala, T.*; Angioni, C.*; Benkadda, S.*; Beurskens, M. N. A.*; Bourdelle, C.*; Brix, M.*; et al.
Nuclear Fusion, 51(7), p.073020_1 - 073020_13, 2011/07
Times Cited Count：12 Percentile：43.58(Physics, Fluids & Plasmas)A variety of triggering mechanisms and structures of internal transport barrier (ITB) has been observed in various devices or depending on operation scenarios. Thus identity experiments on ITB in JT-60U and JET have been performed to shed light on the physics behind ITBs. Because of their similar size, the dimensionless parameters between both devices are the same. These experiments were performed with near identical magnetic configurations, heating waveforms and normalized quantities such as safety factor, magnetic shear, normalized Larmor radius, normalized collision frequency, beta, temperatures ratio. Similarities of the ITB triggering mechanism and the ITB strength have been observed when a proper match is achieved of the most relevant profiles of the normalized quantities. This paper will report on the detail comparison of transport properties of ITBs obtained in these JET/JT-60U identity experiments.
plasmasMatsunaga, Go; Aiba, Nobuyuki; Shinohara, Koji; Sakamoto, Yoshiteru; Takechi, Manabu; Suzuki, Takahiro; Asakura, Nobuyuki; Isayama, Akihiko; Oyama, Naoyuki; Yoshida, Maiko; et al.
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03
Tobita, Kenji; Nishio, Satoshi*; Enoeda, Mikio; Nakamura, Hirofumi; Hayashi, Takumi; Asakura, Nobuyuki; Uto, Hiroyasu; Tanigawa, Hiroyasu; Nishitani, Takeo; Isono, Takaaki; et al.
JAEA-Research 2010-019, 194 Pages, 2010/08
JAEA-Research-2010-019-01.pdf:48.47MBJAEA-Research-2010-019-02.pdf:19.4MB
This report describes the results of the conceptual design study of the SlimCS fusion DEMO reactor aiming at demonstrating fusion power production in a plant scale and allowing to assess the economic prospects of a fusion power plant. The design study has focused on a compact and low aspect ratio tokamak reactor concept with a reduced-sized central solenoid, which is novel compared with previous tokamak reactor concept such as SSTR (Steady State Tokamak Reactor). The reactor has the main parameters of a major radius of 5.5 m, aspect ratio of 2.6, elongation of 2.0, normalized beta of 4.3, fusion out put of 2.95 GW and average neutron wall load of 3 MW/m
. This report covers various aspects of design study including systemic design, physics design, torus configuration, blanket, superconducting magnet, maintenance and building, which were carried out increase the engineering feasibility of the concept.
Sakamoto, Yoshiteru; Matsunaga, Go; Oyama, Naoyuki; Suzuki, Takahiro; Aiba, Nobuyuki; Takenaga, Hidenobu; Isayama, Akihiko; Shinohara, Koji; Yoshida, Maiko; Takechi, Manabu; et al.
Nuclear Fusion, 49(9), p.095017_1 - 095017_8, 2009/09
Times Cited Count：37 Percentile：76.26(Physics, Fluids & Plasmas)This paper reports the recent development of reversed shear plasmas with a high bootstrap current fraction towards reactor relevant regime, especially lower 
regime. By utilizing large volume configuration close to the conductive wall for wall stabilization, the beta limit of the reversed shear plasmas is significantly improved. As a result, high confinement reversed shear plasmas with high bootstrap current fraction exceeding no-wall beta limit are obtained in reactor relevant regime, where 
of 2.7, 
of 2.3 is achieved with reversed profile with 
of 2.3, and then HH
of 1.7, 
/
of 0.87 and 
of 0.9 are also obtained at of 5.3.
Matsukawa, Makoto; Kikuchi, Mitsuru; Fujii, Tsuneyuki; Fujita, Takaaki; Hayashi, Takao; Higashijima, Satoru; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Ide, Shunsuke; Ishida, Shinichi; et al.
Fusion Engineering and Design, 83(7-9), p.795 - 803, 2008/12
Times Cited Count：19 Percentile：73.27(Nuclear Science & Technology)no abstracts in English
Oyama, Naoyuki; Isayama, Akihiko; Suzuki, Takahiro; Koide, Yoshihiko; Takenaga, Hidenobu; Ide, Shunsuke; Nakano, Tomohide; Asakura, Nobuyuki; Kubo, Hirotaka; Takechi, Manabu; et al.
Nuclear Fusion, 47(7), p.689 - 697, 2007/07
Times Cited Count：17 Percentile：49.36(Physics, Fluids & Plasmas)After the installation of FSTs in JT-60U, ripple induced fast ion losses have been reduced by 1/21/3. The increase in the absorbed power at the same injection power can reduce the required number of NB units to sustain a given 
. The smaller recycling level and edge density, which is suitable condition to get higher edge temperature, can be kept longer. The higher edge temperature is essential in keeping the peaked pressure/temperature profile. In addition to this, smaller fast ion losses reduce the effective torque for ctr-rotation and increase in better flexibility of torque input. Then, better quality of 
-ITB was obtained in the plasmas with co-rotation. By making use of these advantages to sustain an ITB, the performance of long-pulse ELMy H-mode plasmas was improved in terms of sustained duration time for both high and high thermal confinement enhancement factor (
). High 
2.3 together with 1 was sustained for 23.1s (
, where 
is the current diffusion time.), which also provide high 
. These long-pulse plasmas are possible candidates for ITER hybrid operation scenario.
Inagaki, Manabu; Kato, Tomoko; Yoshida, Hideji*; Oyamada, Kiyoshi*; Fukaya, Yukiko*; Suzuki, Yuji*; Oi, Takao
JAEA-Research 2007-029, 81 Pages, 2007/03
JAEA-Research-2007-029.pdf:10.88MB
The project of high-level radioactive waste disposal is in activity for the site selection of HLW disposal facility and the performance assessment should be more site-specific rather than site-generic, where the applicability of the achievement of site-generic study such as second progress report (H12) to the site specific is to be clarified. In the same way, it is necessary for biosphere assessment to incorporate the site specific condition to the model. The exposure pathway or concentration of the radio nuclides should be determined according to the site specific geological condition, for example. In this paper, following topics have been selected to start the study to reflect specific geological condition to the biosphere modeling. (1) The literature survey of international and national approaches and issues relating to the treatment of GBIs within biosphere assessments, (2) To develop methodology to estimate the release point of the deep groundwater to the shallow accessible groundwater. (3) To prepare information to estimate water balance this is, in turn, necessary to assess the dilution and/or dispersion of the radionuclides in the shallow accessible groundwater body.
Oyama, Naoyuki; Isayama, Akihiko; Suzuki, Takahiro; Koide, Yoshihiko; Takenaga, Hidenobu; Ide, Shunsuke; Nakano, Tomohide; Asakura, Nobuyuki; Kubo, Hirotaka; Takechi, Manabu; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
After installation of ferritic steel tiles (FSTs) which reduced fast ion losses due to toroidal field ripple, the performance of long-pulse ELMy H-mode plasmas was improved in terms of sustained duration time for both high normalized beta (
) and high thermal confinement enhancement factor (
). High 2.3 together with 1 was sustained for 23.1s (12
) 
, which also provide high 
, which is higher than ITER reference scenario. These long-pulse plasmas are possible candidates for ITER hybrid operation scenario.
Ninomiya, Hiromasa; Akiba, Masato; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Inoue, Nobuyuki; et al.
Journal of the Korean Physical Society, 49, p.S428 - S432, 2006/12
To contribute DEMO and ITER, the design to modify the present JT-60U into superconducting coil machine, named National Centralized Tokamak (NCT), is being progressed under nationwide collaborations in Japan. Mission, design and strategy of this NCT program is summarized.
Kikuchi, Mitsuru; Tamai, Hiroshi; Matsukawa, Makoto; Fujita, Takaaki; Takase, Yuichi*; Sakurai, Shinji; Kizu, Kaname; Tsuchiya, Katsuhiko; Kurita, Genichi; Morioka, Atsuhiko; et al.
Nuclear Fusion, 46(3), p.S29 - S38, 2006/03
Times Cited Count：13 Percentile：39.70(Physics, Fluids & Plasmas)The National Centralized Tokamak (NCT) facility program is a domestic research program for advanced tokamak research to succeed JT-60U incorporating Japanese university accomplishments. The mission of NCT is to establish high beta steady-state operation for DEMO and to contribute to ITER. The machine flexibility and mobility is pursued in aspect ratio and shape controllability, feedback control of resistive wall modes, wide current and pressure profile control capability for the demonstration of the high-b steady state.
Tsuchiya, Katsuhiko; Akiba, Masato; Azechi, Hiroshi*; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; et al.
Fusion Engineering and Design, 81(8-14), p.1599 - 1605, 2006/02
Times Cited Count：1 Percentile：9.39(Nuclear Science & Technology)no abstracts in English
Oyama, Naoyuki; Urano, Hajime; Yoshida, Maiko; Takenaga, Hidenobu; Shinohara, Koji; Sakurai, Shinji; Masaki, Kei; Kamiya, Kensaku; Isayama, Akihiko; Suzuki, Takahiro; et al.
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
no abstracts in English
plasma operationTamai, Hiroshi; Akiba, Masato; Azechi, Hiroshi*; Fujita, Takaaki; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; Hosogane, Nobuyuki; Ichimura, Makoto*; et al.
Nuclear Fusion, 45(12), p.1676 - 1683, 2005/12
Times Cited Count：15 Percentile：43.83(Physics, Fluids & Plasmas)Design studies are shown on the National Centralized Tokamak facility. The machine design is carried out to investigate the capability for the flexibility in aspect ratio and shape controllability for the demonstration of the high-beta steady state operation with nation-wide collaboration, in parallel with ITER towards DEMO. Two designs are proposed and assessed with respect to the physics requirements such as confinement, stability, current drive, divertor, and energetic particle confinement. The operation range in the aspect ratio and the plasma shape is widely enhanced in consistent with the sufficient divertor pumping. Evaluations of the plasma performance towards the determination of machine design are presented.
Aoki, Kenji*; Hibiya, Keisuke*; Shiogama, Yukihiro*; Toida, Masaru*; Yamamoto, T.*; Yoshida, Hiroshi*; Banno, K.*; Kubota, T.*; Shimizu, Y.*; Okutsu, Kazuo*; et al.
PNC TJ1100 94-001, 69 Pages, 1994/02
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