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Watanabe, Tadashi
Proceedings of 11th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-11) (CD-ROM), 8 Pages, 2005/10
no abstracts in English
Kawano, Yasunori; Nakano, Tomohide; Asakura, Nobuyuki; Tamai, Hiroshi; Isayama, Akihiko; Kondoh, Takashi; Hatae, Takaki; Takenaga, Hidenobu; Ide, Shunsuke
Purazuma, Kaku Yugo Gakkai-Shi, 81(10), p.743 - 744, 2005/10
Electron density of post-disruption runaway plasmas in JT-60U has been measured by the tangential CO laser interferometer. Increases in electron density after the first drop of runaway plasma current have been observed during a fast termination phase of the runaway plasma. At the second current drop, an increase in electron density with multiple spikes or oscillation with the period of 1 ms has been found. It is suggested that the increased electron density seems to take part in the shorter current decay time after the second current drop.
Hoshino, Katsumichi; Nagashima, Yoshihiko*; Ido, Takeshi*; Tsuzuki, Kazuhiro; Kawashima, Hisato; Ogawa, Hiroaki; Bakhtiari, M.; Shinohara, Koji; Uehara, Kazuya; Oasa, Kazumi; et al.
Journal of Plasma and Fusion Research SERIES, Vol.6, p.345 - 348, 2004/00
no abstracts in English
Terakado, Masayuki; Seki, Masami; Shimono, Mitsugu; Igarashi, Koichi*; Mitsunaka, Yoshika*; Isayama, Akihiko; Anno, Katsuto; Ikeda, Yoshitaka
JAERI-Tech 2003-053, 25 Pages, 2003/06
The Electron Cyclotron Range of Frequencies (ECRF) system having four 110 GHz-gyrotrons has been successfully operated on JT-60U to locally heat a plasma (ECH) and drive a plasma current (ECCD) for high plasma performance owing to suppressing MHD activities. For investigation of plasma confinement the ECRF power is intermittently injected into plasmas to evaluate thermal conductivity. We have successfully performed power modulation by changing the anode voltage. The power modulation ratio of 80 % is attained changing the anode voltage by only about 10%. Modulation frequency is from 12 Hz to 500 Hz. The mode converter is heated when oscillation efficiency of the main mode decreases in changing the anode voltage. This seems to be due to the parasitic oscillation at the entrance of the converter. The gyrotron will be able to be protected by monitoring the temperature rise in the converter.
Nakamura, Takehiko; Nakamura, Jinichi; Sasajima, Hideo; Uetsuka, Hiroshi
Journal of Nuclear Science and Technology, 40(5), p.325 - 333, 2003/05
Times Cited Count:2 Percentile:18.89(Nuclear Science & Technology)In order to examine high burnup fuel performance and to confirm its integrity under unstable power oscillation conditions arising during an ATWS in BWRs, two tests of irradiated fuels under simulated power oscillation conditions were conducted in the NSRR. Irradiated fuels at burnups of 25 and 56GWd/tU were subjected to four to seven power oscillations, which peaked at 50 to 95kW/m with intervals of 2s. The power oscillation was simulated by quick withdrawal and insertion of six regulating rods of the NSRR with a computerized control. Deformation of the fuel cladding of the test rods was comparable to those observed in shorter transient tests, which simulated RIAs, at the same fuel enthalpy level up to 368J/g. The fuel deformation was mainly caused by PCMI and was roughly proportional to the fuel enthalpy. Enhanced cladding deformation due to ratcheting by the cyclic load was not observed. Fission gas release, on the other hand, was considerably smaller than in the RIA tests, suggesting different release mechanisms in the two types of transients.
Takahashi, Masamitsu; Yoneda, Yasuhiro; Inoue, Hirotane*; Yamamoto, Naomasa*; Mizuki, Junichiro
Journal of Crystal Growth, 251(1-4), p.51 - 55, 2003/04
Times Cited Count:3 Percentile:21.99(Crystallography)The reflection high energy electron diffraction (RHEED) oscillation has been widely adopted for studies on growth kinetics and dynamics in molecular beam epitaxy (MBE). Recent development in brilliant X-ray source has enabled similar experiments with X-rays, which has great advantage in a straightforward interpretation of results and in a high angular resolution. In general, the diffracted intensity from surface is proportional to the surface structure factor associated with the surface reconstruction, F, multiplied by a damping factor associated with the surface roughness, m. We show that the two factors, F and m, can be obtained separately by measuring diffuse scattering around the two-dimensional Bragg peak during growth.
Machida, Masahiko; Koyama, Tomio*
Physical Review Letters, 90(7), p.077003_1 - 077003_4, 2003/02
Times Cited Count:37 Percentile:80.72(Physics, Multidisciplinary)no abstracts in English
Chishiro, Etsuji; Kobayashi, Tetsuya; Yamazaki, Masayoshi*; Suzuki, Hiroyuki*; Hori, Toshihiko*; Sakamoto, Mitsunori*; Urakata, Hiroto*; Miyake, Setsuo*; Fukuda, Shigeki*; Anami, Shozo*
Proceedings of 21st International Linac Conference, p.455 - 457, 2003/00
In the lilac of the High-Intensity Proton Accelerator Facility, 972MHz klystrons are adopted as the RF source for the acceleration from 190MeV to 400MeV. The klystron is required the RF power of 2.5 MW to drive the ACS accelerator. A prototype klystron was produced, and was evaluated the RF characteristics at the test stand in the JAERI. At the first test, a saturation power of 2.1 MW was obtain on the cathode voltage of 104kV, and an unstable output power causing by a gun oscillation was observed.
Kasugai, Atsushi; Sakamoto, Keishi; Hayashi, Kenichi*; Takahashi, Koji; Shoyama, Hiroaki*; Kajiwara, Ken*; Ikeda, Yoshitaka; Kariya, Tsuyoshi*; Mitsunaka, Yoshika*; Fujii, Tsuneyuki; et al.
JAERI-Research 2002-027, 57 Pages, 2002/11
no abstracts in English
Nakamura, Jinichi; Nakamura, Takehiko; Sasajima, Hideo; Suzuki, Motoe; Uetsuka, Hiroshi
HPR-359, Vol.2, p.34_1 - 34_16, 2002/09
In BWR, power oscillations can occur due to the void fraction fluctuation. To investigate the fuel behavior during power oscillation of BWRs, two types of irradiated fuel rods were tested under simulated power oscillation conditions in the Nuclear Safety Research Reactor(NSRR). One is high burnup BWR fuel (56GWd/t) test, with 4 power oscillation cycles, to clarify the behavior of high burnup fuel. The second one is high enriched fuel(20%,25GWd/t) test, with 7 power cycles, to perform the test under high power conditions. The fuel behavior data, such as cladding elongation, fuel stack elongation, cladding temperature, etc. were obtained in these tests. The DNB did not occur in these tests. The PCI was observed through cladding elongation and fuel stack elongation during the power oscillations, but the residual strain of cladding was very small. Fuel behavior under simulated power oscillations is discussed based on in-pile data and PIE data and is compared with FEMAXI-6 and FRAP-T6 calculation.
Nakamura, Takehiko; Katanishi, Shoji; Kashima, Yoichi; Yachi, Shigeyasu; Yoshinaga, Makio; Terakado, Yoshibumi
Journal of Nuclear Science and Technology, 39(3), p.264 - 272, 2002/03
Times Cited Count:8 Percentile:47.73(Nuclear Science & Technology)In order to study fuel behavior under abnormal transients and accidents, the control system of the Nuclear Safety Research Reactor (NSRR) of the Japan Atomic Energy Research Institute (JAERI) was modified to achieve high power transients. With this new operational mode, called Shaped Pulse (SP), transients at the maximum power of 10 MW can be conducted for a few seconds. This new operational mode supplements the previous Natural Pulse (NP) operation at the maximum power of 23 GW for milliseconds. For high power transient operation, a simulator using a point kinetic model was developed, and characteristics of the NSRR in the new operational mode were examined through tests and calculations. With the new operational mode, new types of fuel irradiation tests simulating power oscillations of boiling water reactors (BWRs) can to be conducted in the NSRR. Reactor characteristics and capability, such as control rod worth, feedback reactivity, and operational limits of the NSRR for SP operations are discussed.
Minehara, Eisuke
Oyo Butsuri, 71(2), p.214 - 216, 2002/02
We have developed free-electron lasers driven by a superconducting rf linac to demonstrate a powerful and efficient FEL, and the prototype of the FEL has successfully lased to get 0.1kW as the world-strongest FEL average power in February 1998. Two years after the first lasing, the second world-records of ultra-fast pulse of 250fs, efficiency of 7%, and average and peak power of 2.34kW and 1GW at 22 micron have successfully been obtained using a well-improved FEL and superconducting rf linac driver. The breakthrough of ultra-short pulse, efficiency and power in FELs has been realized using the improved driver performance of high density current and high-quality acceleration, and a discovery of sustained superradiance FEL oscillation. Resultantly, we have been successfully able to demonstrate high-efficiency larger than the theoretical limit and ultra-fast pulse of 3.4cycles, and 250fs. In the text, the novel technology of FELs driven by a superconducting rf linac will be briefly reported.
Kondo, Masaya; Anoda, Yoshinari
Nihon Kikai Gakkai Rombunshu, B, 68(665), p.86 - 93, 2002/01
no abstracts in English
Kondo, Masaya; Anoda, Yoshinari
Emerging Technologies for Fluids, Structures and Fluid-Structure Interaction, 2001 (PVP-Vol.431), p.111 - 117, 2001/07
no abstracts in English
Kondo, Masaya; Anoda, Yoshinari
Emerging Technologies in Fluids, Structures, and Fluid/Structure Interactions (PVP-Vol.414-1), p.171 - 177, 2000/07
no abstracts in English
; Anoda, Yoshinari
Nihon Kikai Gakkai Rombunshu, C, 65(639), p.4252 - 4259, 1999/11
no abstracts in English
Ishikawa, Nobuyuki; Suzuki, Katsuo
JAERI-Research 98-055, 31 Pages, 1998/09
no abstracts in English
J.U.Knebel*; Araya, Fumimasa
Proc. of 2nd Japanese-German Symp. on Multi-phase Flow, p.447 - 453, 1997/00
no abstracts in English
Yonomoto, Taisuke; Kukita, Yutaka
Proc. of the 1995 Int. Joint Power Generation Conf. (NE-Vol. 17), 2, p.25 - 31, 1995/00
no abstracts in English
Yamashita, Kiyonobu; Harada, Hiro; Murata, Isao; Shindo, Ryuichi;
Journal of Nuclear Science and Technology, 30(3), p.249 - 260, 1993/03
Times Cited Count:1 Percentile:18.76(Nuclear Science & Technology)no abstracts in English