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2022)Aso, Tomokazu; Ariyoshi, Gen; Muto, Hideki*; Tanaka, Shigeto*
JAEA-Technology 2025-005, 51 Pages, 2025/10
JAEA-Technology-2025-005.pdf:2.47MB
The cryogenic hydrogen system of the J-PARC center is one of the most important pieces equipment, which is a refrigeration system for moderating (cooling) the high energy neutrons generated the spallation neutron source of the Material and Life Science Experimental Facility (MLF) that is used by many users from Japan and abroad. Since the first operation of the MLF for neutron use in 2008, the cryogenic hydrogen system has been continuously operated and maintained, and related technology development has been carried out. This report summarized these activities over the past five years.
Yano, Rei*; Tanaka, Masaki*; Yamasaki, Shigeto*; Morikawa, Tatsuya*; Tsuru, Tomohito
Materials Transactions, 65(10), p.1260 - 1267, 2024/10
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)Impact tests and tensile tests were conducted between 77K and 450K in order to elucidate the temperature dependence of absorbed-impact energy, yield stress, effective shear stress, activation volume, and activation enthalpy. The impact-absorbed energy decreased with decreasing test temperature, however, this alloy did not undergo low-temperature embrittlement although it has a bcc structure. Tensile tests showed changes in both the work-hardening rate and the temperature dependence of yield stress at approximately 120 K. This suggests a change in the mechanism behind the plastic deformation at the temperature. The temperature dependence of the activation enthalpy for dislocation glide suggests that double-kink nucleation of a screw dislocation is the dominant mechanism for the dislocation glide from 150K to 200 K, while the interaction between a dislocation and solute atoms dominantly controls the dislocation glide above 200 K. Superelasticity appears in stress-strain curves tested below 120 K, suggesting that the yielding is governed by transformation-induced plasticity below 120 K. The enhanced toughness at low temperatures in these alloys is discussed from the viewpoint of dislocation shielding theory.
Yano, Rei*; Tanaka, Masaki*; Yamasaki, Shigeto*; Morikawa, Tatsuya*; Tsuru, Tomohito
Keikinzoku, 73(10), p.497 - 503, 2023/10
Impact tests and tensile tests were conducted between 77 K and 450 K in order to elucidate the temperature dependence of absorbed-impact energy, yield stress, effective shear stress, and activation volume. The impact-absorbed energy decreased with decreasing test temperature, however, this alloy did not undergo low-temperature embrittlement although it has a bcc structure. Tensile tests showed changes in both the work-hardening rate and the temperature dependence of yield stress at approximately 120 K. This suggests a change in the mechanism behind the plastic deformation at the temperature. The temperature dependence of the activation enthalpy for dislocation glide suggests that double-kink nucleation of a screw dislocation is the dominant mechanism for the dislocation glide from 150 K to 200 K, while the interaction between a dislocation and solute atoms dominantly controls the dislocation glide above 200 K. On the other hand, superelasticity appears below 120 K, suggesting that the yielding is governed by transformation-induced plasticity below 120 K. The enhanced toughness at low temperatures in these alloys is discussed from the viewpoint of dislocation shielding theory.
Takahashi, Sentaro*; Kawashima, Shigeto*; Hidaka, Akihide; Tanaka, Sota*; Takahashi, Tomoyuki*
Nuclear Technology, 205(5), p.646 - 654, 2019/05
Times Cited Count：4 Percentile：31.67(Nuclear Science & Technology)
produced by ion beam irradiation with an improved ability to uptake and assimilate atmospheric nitrogen dioxideTakahashi, Misa*; Kohama, S.*; Shigeto, Jun*; Hase, Yoshihiro; Tanaka, Atsushi; Morikawa, Hiromichi*
International Journal of Phytoremediation, 14(3), p.275 - 281, 2012/03
Times Cited Count：3 Percentile：8.60(Environmental Sciences)Production of novel mutants with a high ability to mitigate pollutants is important for phytoremediation. We investigated the use of ion beam irradiation to produce mutants of L. with an improved ability to mitigate atmospheric (NO
). More than 25,000 shoot explants were irradiated with ion beams, from which 263 independent plant lines were obtained. The plants were analyzed for NO uptake by fumigation with 1 ppm 
N-labeled NO, followed by mass spectrometric analysis. The mean NO uptake values of each lines differed over a 110-fold range. Propagation was attempted using cuttings from 44 lines showing the greatest NO uptake; in total, 15 lines were propagated. Two of the 15 lines showed a mean NO uptake 1.7- to 1.8-fold greater than that of the wild-type. This increase in NO uptake was heritable in both lines; their progenies showed a significantly greater ability to take up and assimilate NO than did the wild-type. RAPD analysis demonstrated DNA variation between the progeny plants and the wild type, suggesting that the progeny were true mutants. These mutants of 
may prove useful in mitigating atmospheric NO.
Ushigome, Masahiro*; Ide, Shunsuke; Ito, Satoshi*; Jotaki, Eriko*; Mitarai, Osamu*; Shiraiwa, Shunichi*; Suzuki, Takahiro; Takase, Yuichi*; Tanaka, Shigetoshi*; Fujita, Takaaki; et al.
Nuclear Fusion, 46(2), p.207 - 213, 2006/02
Times Cited Count：12 Percentile：37.80(Physics, Fluids & Plasmas)This papaer studies on tokamak plasma start-up completely without central solenoid (CS). On the JT-60 tokamak it is demonstrated that a completely CS-less Ip start-up to 100 kA was achieved even without any null-point by Electron cyclotron range of frequencies (ECRF) and outer PF coil current swing only. Necessary conditions (the EC power, the toroidal field etc.) were clarified. Moreover, it was succeded to maintain Ip = 260kA for 1 sec without CS by NB only. In addition Ip ramp-up by EC and NB only (without LHCD) from 215 to 310kA was achieved. In a high confinement reversed shear discharge, a result suggesting bootstrap over drive was obtained.
Shiraiwa, Shunichi*; Ide, Shunsuke; Ito, Satoshi*; Mitarai, Osamu*; Naito, Osamu; Ozeki, Takahisa; Sakamoto, Yoshiteru; Suzuki, Takahiro; Takase, Yuichi*; Tanaka, Shigetoshi*; et al.
Physical Review Letters, 92(3), p.035001_1 - 035001_4, 2004/01
Times Cited Count：53 Percentile：84.36(Physics, Multidisciplinary)no abstracts in English
Sato, Yasunori*; Yamaguchi, Daichi*; Oshima, Akihiro*; Kato, Takanori*; Ikeda, Shigetoshi*; Aoki, Yasushi*; Tanaka, Shigeru; Tabata, Yoneho*; Washio, Masakazu*
JAERI-Conf 2003-001, p.245 - 250, 2003/03
no abstracts in English
plants that have high phytoremediation ability for nitrogen dioxide by ion beam breedingTakahashi, Misa*; Kohama, S.*; Shigeto, Jun*; Sakamoto, Atsushi*; Hase, Yoshihiro; Tanaka, Atsushi; Morikawa, Hiromichi*
no journal, ,
no abstracts in English
