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Journal Articles

A Proposal of secure non-destructive detection system of nuclear materials in heavily shielded objects and interior investigation system

Seya, Michio; Hajima, Ryoichi*; Kureta, Masatoshi

Proceedings of INMM 58th Annual Meeting (Internet), 10 Pages, 2017/07

Large size freight cargo containers are the most vulnerable items from nuclear security points of view because of their large volume and weight of cargo inside for hiding heavily shielded objects. For strengthening nuclear security, secure detection of NMs in heavily shielded objects, and safe handling (dismantlement) of detected (suspicious) objects, are essential. These require secure detection of NMs, inspection of detailed interior structures of detected objects, rough characterization of NMs (for nuclear bomb or RDD etc.) and confirmation of existence of explosives etc. By using information obtained by these inspections, safe dismantlement of objects is possible. In this paper, we propose a combination of X-ray scanning system with NRF-based NDD system using monochromatic $$gamma$$-ray beam for a secure detection and interior inspections. We also we propose active neutron NDA system using a DT source for interior inspection of NM part.

Journal Articles

Heating, current drive, and advanced plasma control in JFT-2M

Hoshino, Katsumichi; Yamamoto, Takumi; Tamai, Hiroshi; Oasa, Kazumi; Kawashima, Hisato; Miura, Yukitoshi; Ogawa, Toshihide; Shoji, Teruaki*; Shibata, Takatoshi; Kikuchi, Kazuo; et al.

Fusion Science and Technology, 49(2), p.139 - 167, 2006/02

 Times Cited Count:2 Percentile:18.25(Nuclear Science & Technology)

The main results obtained by the various heating and current drive systems, external coil system and divertor bias system are reviewed from the viewpoint of the advanced active control of the tokamak plasma. Also, the features of each system are described. The contribution of the JFT-2M in these areas are summarized.

Journal Articles

Development and contribution of RF heating and current drive systems to long pulse, high performance experiments in JT-60U

Moriyama, Shinichi; Seki, Masami; Terakado, Masayuki; Shimono, Mitsugu; Ide, Shunsuke; Isayama, Akihiko; Suzuki, Takahiro; Fujii, Tsuneyuki; JT-60 Team

Fusion Engineering and Design, 74(1-4), p.343 - 349, 2005/11

 Times Cited Count:7 Percentile:47.08(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Recent RF experiments and application of RF waves to real-time control of safety factor profile in JT-60U

Suzuki, Takahiro; Isayama, Akihiko; Ide, Shunsuke; Fujita, Takaaki; Oikawa, Toshihiro; Sakata, Shinya; Sueoka, Michiharu; Hosoyama, Hiroki*; Seki, Masami; JT-60 Team

AIP Conference Proceedings 787, p.279 - 286, 2005/09

A real-time control system of safety factor (q) profile was developed in JT-60. This system, for the first time, enables 1) real time evaluation of q profile using local magnetic pitch angle measurement by motional Stark effect (MSE) diagnostic and 2) control of current drive (CD) location (rhoCD) by adjusting the parallel refractive index $$N_{rm //}$$ of lower-hybrid (LH) waves through the change of phase difference (dphi) of LH waves between multi-junction launcher modules. The method for q profile evaluation was newly developed, without time-consuming reconstruction of equilibrium, so that the method requires less computational time. The system evaluates q profile within every 10ms, which is much faster than current relaxation time, typically order of 1s. Safety factor profile by the real-time calculation agreed well with that by equilibrium reconstruction with MSE. From temporal evolution of q (or current) profile, we evaluate CD location in real-time, too. The control system controls rhoCD through $$N_{rm //}$$ (or directly dphi) in such a way to minimize difference between the real-time evaluated q profile and its reference profile. The real-time control system was applied to positive shear plasmas ($$q(0)sim 1$$), having plasma current of 0.6MA, toroidal field of 2.3T, and electron density of $$0.5times 10^{19}{rm m}^{-3}$$. In order to keep good coupling of LH waves to the plasma, gap between the launcher and the plasma surface was controlled to about 0.1m. The reference q profile was set to q(0)=1.3. The real-time q profile approached to the reference after application of real-time control; the controlled q profile was sustained for 3s, which was limited by injected LH power. RF experiments in JT-60U, such as stabilization of neo-classical tearing modes, plasma startup experiments, etc., are also presented.

Journal Articles

Concept and results of new operation scheme with improved control system for radio frequency heating in JT-60U

Moriyama, Shinichi; Shinozaki, Shinichi

Japanese Journal of Applied Physics, Part 1, 44(8), p.6224 - 6229, 2005/08

 Times Cited Count:0 Percentile:0(Physics, Applied)

The control system of RF heating system in JT-60U has been improved with a concept of dispersion processing and featuring a real time waveform shaping method. It is proper that the brand-new, dispersion processing system has higher performance and reliability than old single processor system before modification, however it is worthy of mention that improvement on operation roll sharing, using the real time waveform shaping, has enabled more efficient and smooth operation. The typical roll sharing is that a simple rectangular waveform of the RF heating power is set by the experiment operator, and the waveform is re-shaped with the parameter set by the RF operator who knows deeply the condition of the RF system at that time. The simple and flexible composition of the new control system will also enable further improvement of hardware to enhance plasma performance that is inevitable to the devices for fusion experiment.

JAEA Reports

Research and development of remote maintenance equipment for ITER divertor maintenance

Takeda, Nobukazu; Kakudate, Satoshi; Nakahira, Masataka

JAERI-Tech 2004-071, 85 Pages, 2005/02

JAERI-Tech-2004-071.pdf:4.81MB

To facilitate easy maintainability, the ITER divertor is divided into 60 cassettes, which are transported for replacement using the remote equipments. The cassette of 25 tons has to be transported and installed with a positioning accuracy less than 2 mm in the limited space under the intense gamma radiation field. Based on these requirements, the following design and tests were performed. (1) Link mechanism was studied to apply to the transportation. A compact mechanism with links is designed through the optimization of the link angle taking account of space requirement and force efficiency. The lifting capacity of 30 tons has been demonstrated. (2) Compact link mechanism was also studied to apply for locking of the cassette. The final positioning accuracy of 0.03 mm for installation from the initial positioning error of 5 mm has been demonstrated. (3) Sensor-based control of the remote equipment was tested using simple sensors. It is found that the positioning accuracy of 0.16 mm has been achieved and this value is sufficient.

Journal Articles

Operational progress of the 110GHz-4MW ECRF heating system in JT-60U

Fujii, Tsuneyuki; Seki, Masami; Moriyama, Shinichi; Terakado, Masayuki; Shinozaki, Shinichi; Hiranai, Shinichi; Shimono, Mitsugu; Hasegawa, Koichi; Yokokura, Kenji; JT-60 Team

Journal of Physics; Conference Series, 25, p.45 - 50, 2005/00

The JT-60U electron cyclotron range of frequency (ECRF) is utilized to realize high performance plasma. Its output power is 4 MW at 110 GHz. By controlling the anode voltage of the gyrotron used in the JT-60U ECRF heating system, the gyrotoron output can be controlled. Then, the anode voltage controller was developed to modulate the injected power into plasmas. This low cost controller achieved the modulation frequency 12 - 500 Hz at 0.7 MW. This controller also extended the pulse width from 5s to 16 s at 0.5 MW. For these long pulses, temperature rise of the DC break made of Alumina ceramics is estimated. Its maximum temperature becomes $$sim$$ 140 deg. From the analysis of this temperature rise, DC break materials should be changed to low loss materials for the objective pulse width of 30 s. The stabilization of neoclassical tearing mode (NTM) was demonstrated by ECRF heating using the real-time system in which the ECRF beams are injected to the NTM location predicted from ECE measurement every 10 ms.

Journal Articles

Overview of JT-60U diagnostics for reactor-relevant plasma physics

Hatae, Takaki; JT-60 Team

Proceedings of 6th Japan-Australia Workshop on Plasma Diagnostics (CD-ROM), 16 Pages, 2002/00

The diagnostic system of JT-60U is composed of about 50 individual diagnostic devices. Recently, the detailed radial profile measurements of plasma parameters such as electron temperature, electron density, ion temperature, plasma rotation, and plasma current (safety factor q) have been improved. As a result, the understanding of internal structure of plasmas has advanced. In particular, detailed studies of the internal transport barrier could be performed in reversed magnetic shear plasmas. Furthermore, a "current hole" or a nearly zero current density at the plasma center was discovered in JT-60U plasmas by using a motional stark effect (MSE) system. Several diagnostic signal have been linked to actuators such as neutral beam injectors, the gas feed system, and the electron cyclotron heating system establishing the real-time control of electron temperature, neutron yield, radiated power, and electron temperature gradient, and thus improving plasma performance.

Journal Articles

Impurity behavior before and during the X-point MARFE in JT-60U

Higashijima, Satoru; Kubo, Hirotaka; Sugie, Tatsuo; Nakano, Tomohide; Konoshima, Shigeru; Tamai, Hiroshi; Shimizu, Katsuhiro; Sakasai, Akira; Asakura, Nobuyuki; Sakurai, Shinji; et al.

Journal of Nuclear Materials, 290-293, p.623 - 627, 2001/03

 Times Cited Count:5 Percentile:40.34(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Performance test of the HTTR

Tanaka, Toshiyuki; Okubo, Minoru; Iyoku, Tatsuo; Kunitomi, Kazuhiko; Takeda, Takeshi; Sakaba, Nariaki; Saito, Kenji

Nihon Genshiryoku Gakkai-Shi, 41(6), p.686 - 698, 1999/00

 Times Cited Count:4 Percentile:36.04(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

RF control at transient beamloading for high-duty-factor linacs

M.A.Chernogubovsky*; Sugimoto, Masayoshi

JAERI-Research 98-041, 29 Pages, 1998/08

JAERI-Research-98-041.pdf:1.32MB

no abstracts in English

Journal Articles

RF signal optimization for beamloaded accelerator control

M.Chernogubovsky*

Proc. of 11th Symp. on Accelerator Sci. and Technol., p.221 - 223, 1997/00

no abstracts in English

Journal Articles

Development of visual beam adjustment method for cyclotron

Agematsu, Takashi; Arakawa, Kazuo; Okumura, Susumu; Nakamura, Yoshiteru; Yokota, Wataru; Nara, Takayuki; Ishibori, Ikuo

JAERI-Review 95-019, p.211 - 213, 1995/10

no abstracts in English

Journal Articles

Application of fuzzy theory to radiation control

Hoken Butsuri, 29, p.460 - 462, 1994/00

no abstracts in English

Journal Articles

VME and network applications for the JT-60U control system

Kimura, Toyoaki

Nuclear Instruments and Methods in Physics Research A, 352, p.125 - 127, 1994/00

 Times Cited Count:1 Percentile:27.87(Instruments & Instrumentation)

no abstracts in English

Journal Articles

The Three-dimensional thermal analysis for the stand-pipe room of HTTR by the STREAM code

Takeda, Takeshi; Kunitomi, Kazuhiko; Baba, Osamu

Proc. 6th Int. Topical Meeting on Nuclear Reactor Thermal Hydraulics,Vol. 1; NURETH6, 0, p.1483 - 1488, 1994/00

no abstracts in English

JAEA Reports

A Study on cooling air flow around stand-pipes for the High Temperature Engineering Test Reactor

Takeda, Takeshi; Kunitomi, Kazuhiko; *

JAERI-M 93-215, 32 Pages, 1993/10

JAERI-M-93-215.pdf:1.33MB

no abstracts in English

Journal Articles

Development of visual beam adjustment method for cyclotron

Agematsu, Takashi; Arakawa, Kazuo; Okumura, Susumu; Nakamura, Yoshiteru; Yokota, Wataru; Nara, Takayuki; Fukuda, Mitsuhiro; Ishibori, Ikuo; *; Tachikawa, T.*

Proc. of the 9th Symp. on Accelerator Science and Technology, p.65 - 67, 1993/00

no abstracts in English

Journal Articles

Selected reactor physics phenomena observed during N.S.Mutsu power-up tests

; Miyoshi, Yoshinori; *; *; ;

Proc. of the Int. Conf. on Nuclear Power Plant Operations; Ready for 2000, p.435 - 441, 1992/00

no abstracts in English

Journal Articles

Radiation protection in decontamination work of hot cells in reactor fuel examination facility

Sato, Nobuyuki; ; Kobayashi, Makoto; Nakazawa, Takashi; ; ; Ikezawa, Yoshio

Proc. of the Int. Conf. on Radiation Effects and Protection, p.440 - 445, 1992/00

no abstracts in English

30 (Records 1-20 displayed on this page)