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Kumada, Takayuki; Akutsu, Kazuhiro*; Oishi, Kazuki*; Morikawa, Toshiaki*; Kawamura, Yukihiko*; Sahara, Masae*; Suzuki, Junichi*; Miura, Daisuke*; Torikai, Naoya*
J-PARC 20-02; J-PARC MLF Annual Report 2019, p.38 - 40, 2021/00
Shimazaki, Yosuke; Sawahata, Hiroaki; Kawamoto, Taiki; Suzuki, Hisashi; Shinohara, Masanori; Honda, Yuki; Katsuyama, Kozo; Takada, Shoji; Sawa, Kazuhiro
Journal of Nuclear Engineering and Radiation Science, 2(4), p.041008_1 - 041008_5, 2016/10
Maintenance technologies for the reactor system have been developed by using the high-temperature engineering test reactor (HTTR). One of the important purposes of development is to accumulate the experiences and data to satisfy the availability of operation up to 90% by shortening the duration of the periodical maintenance for the future HTGRs by shifting from the time-based maintenance to condition-based maintenance. The technical issue of the maintenance of in-core neutron detector, wide range monitor (WRM), is to predict the malfunction caused by cable disconnection to plan the replacement schedule. This is because that it is difficult to observe directly inside of the WRM in detail. The electrical inspection method was proposed to detect and predict the cable disconnection of the WRM by remote monitoring from outside of the reactor by using the time domain reflectometry and so on. The disconnection position, which was specified by the electrical method, was identified by non-destructive and destructive inspection. The accumulated data is expected to be contributed for advanced maintenance of future HTGRs.
Shimazaki, Yosuke; Sawahata, Hiroaki; Kawamoto, Taiki; Suzuki, Hisashi; Shinohara, Masanori; Honda, Yuki; Katsuyama, Kozo; Takada, Shoji; Sawa, Kazuhiro
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05
Maintenance technologies for the reactor system have been developed by using the high-temperature engineering test reactor (HTTR). One of the important purposes of development is to accumulate the experiences and data to satisfy the availability of operation up to 90% by shortening the duration of the periodical maintenance for the future HTGRs by shifting from the time-based maintenance to condition-based maintenance. The technical issue of the maintenance of in-core neutron detector, wide range monitor (WRM), is to predict the malfunction caused by cable disconnection to plan the replacement schedule. This is because that it is difficult to observe directly inside of the WRM in detail. The electrical inspection method was proposed to detect and predict the cable disconnection of the WRM by remote monitoring from outside of the reactor by using the time domain reflectometry and so on. The disconnection position, which was specified by the electrical method, was identified by non-destructive and destructive inspection. The accumulated data is expected to be contributed for advanced maintenance of future HTGRs.
Yamazaki, Dai; Soyama, Kazuhiko; Ebisawa, Toru*; Takeda, Masayasu; Torikai, Naoya*; Tasaki, Seiji*; Matsuoka, Hideki*
Physica B; Condensed Matter, 356(1-4), p.229 - 233, 2005/02
Times Cited Count：1 Percentile：6.20(Physics, Condensed Matter)The application of neutron reflectometry to study dynamic phenomena at surface and interfaces have been restricted so far. It was mainly due to the low intensity of neutron sources, but now high-intensity spallation neutron sources are under construction in Japan (J-PARC) and U.S. (SNS). We have a plan to install a spin-echo option on the J-PARC neutron reflectometer with horizontal sample geometry for studies on dynamics of surfaces and interfaces. This option is based on the resonance spin-echo method and aimed at dynamics upto hundreds of nanoseconds. In this contribution, the plan and status of development are introduced together with the principle and characteristics of this option.
Bruskin, L. G.; Oyama, Naoyuki; Shinohara, Koji; Miura, Yukitoshi; Kogi, Yuichiro*; Mase, Atsushi*; Hasegawa, Makoto*; Hanada, Kazuaki*
Review of Scientific Instruments, 74(3), p.1473 - 1476, 2003/03
Times Cited Count：5 Percentile：33.06(Instruments & Instrumentation)An analytical model of fluctuation reflectometry is developed, which is capable of handling the plasma profiles of arbitrary shape and curvature. The experimental profiles are piece-wise approximated by the functions, which allow for the integration of the full-wave O-mode equation. The model is applied to the reflectometry of the JT-60U tokamak plasma to provide a preliminary estimation of the fluctuation amplitude and spectral width.
Bruskin, L. G.; Mase, Atsushi*; Oyama, Naoyuki; Miura, Yukitoshi
Plasma Physics and Controlled Fusion, 44(11), p.2305 - 2325, 2002/11
Times Cited Count：17 Percentile：48.70(Physics, Fluids & Plasmas)The results of analytical solution of time-dependent 2D full-wave equation are presented here for the case of fluctuation reflectometry. We consider a family of plasma density profiles with cylindrical symmetry, which allow for an integration of the microwave scattering equation. Based on the results of analytical modeling, Doppler reflectometry as a method of plasma velocity measurements is investigated. It is shown that the accuracy of Doppler shift measurements is sensitive to the spectral content of the broadband turbulence, as well as to the curvature of the plasma cut-off layer. Addressing the problem of fluctuation amplitude measurements, it is suggested that a power-related parameter of the microwave signal, called fluctuation index, is suitable to quantify the plasma turbulence level provided that the fluctuation spectrum is a priori estimated.
Bruskin, L. G.; Mase, Atsushi*
Journal of the Physical Society of Japan, 71(5), p.1274 - 1279, 2002/05
Times Cited Count：3 Percentile：29.19(Physics, Multidisciplinary)The results of analytical solution of the time-dependent 2D full wave equation in cylindrical coordinates are presented here with application to plasma fluctuation reflectometry. We consider a family of plasma density profiles with cylindrical symmetry, which allow for a full integrationof the microwave scattering problem in Born approximation. Based on the results of analytical modeling, the effects of beam refraction and scattering are studied taking into account possible asymmetries such as antenna misalignments and movement of plasma fluctuations. It is shown that the reflectometer sensitivity to the small radial scale fluctuations increases in the plasma with the high curvature. It is also noted that the microwave reflectometry measurements are better localized in high curvature plasmas.
Bruskin, L. G.; Mase, Atsushi*
Review of Scientific Instruments, 72(11), p.4139 - 4144, 2001/11
Times Cited Count：0 Percentile：0.01(Instruments & Instrumentation)no abstracts in English
Bruskin, L. G.; Mase, Atsushi*; Yamamoto, A.*; Kogi, Yuichiro*
Plasma Physics and Controlled Fusion, 43(10), p.1333 - 1349, 2001/10
Times Cited Count：14 Percentile：43.39(Physics, Fluids & Plasmas)no abstracts in English
Soyama, Kazuhiko
Radioisotopes, 46(11), p.852 - 858, 1997/11
no abstracts in English
Soyama, Kazuhiko; Metoki, Naoto; Minakawa, Nobuaki; ;
Hamon, 7(2), p.5 - 7, 1997/05
no abstracts in English
Soyama, Kazuhiko; Suzuki, Masatoshi
ASRR-V: Proc., 5th Asian Symp. on Research Reactors, 2, p.894 - 900, 1996/00
no abstracts in English
Soyama, Kazuhiko; Metoki, Naoto; Minakawa, Nobuaki; Morii, Yukio; ;
Journal of the Physical Society of Japan, 65(A), p.133 - 135, 1996/00
no abstracts in English
