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Journal Articles

Sodium-cooled Fast Reactors

Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.

Journal Articles

Thermally altered subsurface material of asteroid (162173) Ryugu

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:30 Percentile:96.87(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 $$^{circ}$$C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 $$^{circ}$$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.

Journal Articles

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

 Times Cited Count:233 Percentile:99.74(Multidisciplinary Sciences)

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Journal Articles

Secondary sodium fire measures in JSFR

Chikazawa, Yoshitaka; Kato, Atsushi*; Yamamoto, Tomohiko; Kubo, Shigenobu; Ohno, Shuji; Iwasaki, Mikinori*; Hara, Hiroyuki*; Shimakawa, Yoshio*; Sakaba, Hiroshi*

Nuclear Technology, 196(1), p.61 - 73, 2016/10

 Times Cited Count:1 Percentile:10.78(Nuclear Science & Technology)

JSFR adopts double boundary for all sodium components. However, design measures are investigated for the secondary sodium fire inside the reactor building, which might be assumed as design extension conditions (DECs). Candidates of sodium fire measures in the secondary sodium systems such as sodium drain, nitrogen injection, pressure release valve, catch pan and leak sodium drain system have been compared from the view point of safety. Wide range of sodium fires in the steam generator room and air cooler have been analyzed evaluating performances of the candidate sodium fire measures.

Journal Articles

22A beam production of the uniform negative ions in the JT-60 negative ion source

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Grisham, L. R.*; Hatayama, Akiyoshi*; Shibata, Takanori*; Yamamoto, Takashi*; Akino, Noboru; Endo, Yasuei; et al.

Fusion Engineering and Design, 96-97, p.616 - 619, 2015/10

 Times Cited Count:11 Percentile:67.6(Nuclear Science & Technology)

In JT-60 Super Advanced for the fusion experiment, 22A, 100s negative ions are designed to be extracted from the world largest ion extraction area of 450 mm $$times$$ 1100 mm. One of the key issues for producing such as high current beams is to improve non-uniform production of the negative ions. In order to improve the uniformity of the negative ions, a tent-shaped magnetic filter has newly been developed and tested for JT-60SA negative ion source. The original tent-shaped filter significantly improved the logitudunal uniformity of the extracted H$$^{-}$$ ion beams. The logitudinal uniform areas within a $$pm$$10 deviation of the beam intensity were improved from 45% to 70% of the ion extraction area. However, this improvement degrades a horizontal uniformity. For this, the uniform areas was no more than 55% of the total ion extraction area. In order to improve the horizontal uniformity, the filter strength has been reduced from 660 Gasus$$cdot$$cm to 400 Gasus$$cdot$$cm. This reduction improved the horizontal uniform area from 75% to 90% without degrading the logitudinal uniformity. This resulted in the improvement of the uniform area from 45% of the total ion extraction areas. This improvement of the uniform area leads to the production of a 22A H$$^{-}$$ ion beam from 450 mm $$times$$ 1100 mm with a small amount increase of electron current of 10%. The obtained beam current fulfills the requirement for JT-60SA.

Journal Articles

Development of the supervisory systems for the ITER diagnostic systems in JADA

Yamamoto, Tsuyoshi; Hashimoto, Yasunori*; Serizawa, Yasunori*; Inamoto, Shuji*; Sato, Kazuyoshi; Sugie, Tatsuo; Takeuchi, Masaki; Kawano, Yasunori

Fusion Engineering and Design, 89(5), p.532 - 535, 2014/05

 Times Cited Count:1 Percentile:8.95(Nuclear Science & Technology)

The diagnostic systems are essential for the plasma control and physics understandings. JAEA has proposed the new concept of supervisory system which manages operation sequences, current state and configuration parameters for the measurement based on our experiences in operating plasma diagnostic systems. We designed the supervisory system satisfying the requirements from both CODAC system and diagnostic systems. In our design, the tool which converts operational steps described as flowcharts into EPICS Records templates is introduced. This tool will ensure reduction of the system designers' efforts. We also designed the sequencing simulator that can submit transition commands internally instead of CODAC system for the calibration and commissioning. The mechanism which changes the limit values and consistency check algorithms in accordance with the conditions of the diagnostics system is also proposed.

Journal Articles

Evaluation of sodium combustion in the JSFR SCCV

Kato, Atsushi; Chikazawa, Yoshitaka; Yamamoto, Tomohiko; Ohno, Shuji; Kubo, Shigenobu; Sakaba, Hiroshi*; Akiyama, Yo*; Iwasaki, Mikinori*

Proceedings of 2013 International Congress on Advances in Nuclear Power Plants (ICAPP 2013) (USB Flash Drive), 9 Pages, 2013/04

After the accident of TEPCO's Fukushima Dai-ichi Nuclear Power Plant, evaluations of severe events beyond the design basis on a NPP are focused. As one of those activities, wide range of sodium combustion and hydrogen generation potentials have been analyzed to investigate potential consequences on SCCV. Structural and boundary integrity of SCCV have been evaluated from sodium combustion analyses for pressure and temperature loads. Hydrogen generation has also been evaluated as potential loads of SCCV.

Journal Articles

Combustion characteristics of generating hydrogen during sodium-concrete reaction

Seino, Hiroshi; Ohno, Shuji; Yamamoto, Ikuo*; Miyahara, Shinya

Proceedings of 8th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-8) (USB Flash Drive), 10 Pages, 2012/12

A hydrogen combustion experiment was conducted to simulate the sodium-concrete reaction under oxygen-existing conditions. As a result, it was found that hydrogen was burnt at the sodium pool surface because as sodium combustion heat played a role of the ignition energy, and the hydrogen combination ratio increased with the increase of the oxygen concentration in the atmosphere.

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2010

Kunimaru, Takanori; Mikake, Shinichiro; Nishio, Kazuhisa; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Ishibashi, Masayuki; Ueno, Takashi; Tokuyasu, Shingo; Daimaru, Shuji; Takeuchi, Ryuji; et al.

JAEA-Review 2012-020, 178 Pages, 2012/06

JAEA-Review-2012-020.pdf:33.16MB

Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) Project in crystalline rock environment in order to construct scientific and technological basis for geological disposal of High-level Radioactive Waste (HLW). The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). The MIU Project has been ongoing the Phase II. And Phase III started in 2010 fiscal year. This report shows the results of the investigation, construction and collaboration studies in fiscal year 2010, as a part of the Phase II based on the MIU Master Plan updated in 2002.

Journal Articles

Development on in-reactor observation system using cherenkov light

Tsuchiya, Kunihiko; Kitagishi, Shigeru; Nagao, Yoshiharu; Takemoto, Noriyuki; Naka, Michihiro; Kimura, Akihiro; Sano, Tadafumi*; Unesaki, Hironobu*; Yoshimoto, Takaaki*; Nakajima, Ken*; et al.

KURRI Progress Report 2009, P. 196, 2010/10

no abstracts in English

JAEA Reports

Development of waste management system, 1; Concept construction of the system

Kuroki, Ryoichiro; Ito, Fuminori*; Nakata, Hisakazu; Yamamoto, Shuji; Takahashi, Kuniaki

JAEA-Technology 2009-016, 124 Pages, 2009/06

JAEA-Technology-2009-016.pdf:3.8MB

The concept of "Waste Management System" which manages all the waste data from generation to disposal in Japan Atomic Energy Agency (JAEA) was studied. At first, development policy was defined on investigation results of the present state and problem of waste management in JAEA, and target information supplied by "Waste Management System" were extracted. Then over 400 data items to be managed in this system, system configuration and specific functions were shown as system concept. The waste data managed on this system are classified into two categories; for quality assurance of waste packages and for optimization study of waste conditioning and disposal and information service. This system consists of analytical part (i.e. program) and management part (i.e. database) for each data, then all these parts are constructed on network.

Journal Articles

Flowability measurement of coarse particles using vibrating tube method

Ishii, Katsunori; Suzuki, Masahiro; Yamamoto, Takuma; Kihara, Yoshiyuki; Kato, Yoshiyuki; Kurita, Tsutomu; Yoshimoto, Katsunobu; Yasuda, Masatoshi*; Matsusaka, Shuji*

Journal of Chemical Engineering of Japan, 42(5), p.319 - 324, 2009/05

 Times Cited Count:7 Percentile:29.83(Engineering, Chemical)

The flowability of coarse particles has been experimentally investigated using the vibrating tube method, to evaluate the applicability of this method to MOX (mixed oxide of PuO$$_{2}$$ and UO$$_{2}$$) particles which are nuclear fuel used for electric power production. Five sizes of non-radioactive model particles, smaller than 850 micrometers, made of ZrO$$_{2}$$ were prepared, and the experiments were carried out using vibrating tubes with an outlet diameter from 2 to 4 mm. The outlet diameter significantly affected the flowability measurements. When using the tube with a 4-mm-outlet diameter, the flowability of all the model particles was successfully measured. The inclination angle of the tube, also, affected the flowability measurements. From the advantages of high sensitivity, short measurement time, simple structure, and easy operation, the vibrating tube method is expected to be applied to the remote flowability measurement of the MOX particles.

Journal Articles

New method to measure the rise time of a fast pulse slicer for laser ion acceleration research

Mori, Michiaki; Yogo, Akifumi; Kiriyama, Hiromitsu; Nishiuchi, Mamiko; Ogura, Koichi; Orimo, Satoshi; Ma, J.*; Sagisaka, Akito; Kanazawa, Shuhei; Kondo, Shuji; et al.

IEEE Transactions on Plasma Science, 36(4), p.1872 - 1877, 2008/08

 Times Cited Count:7 Percentile:28.59(Physics, Fluids & Plasmas)

A dependence of cut-off proton kinetic energy on laser prepulse duration has been observed. ASE pedestal duration is controlled by a fast electro-optic pulse slicer where the risetime is estimated to be 130 ps. We demonstrate a new correlated spectral technique for determining this risetime using a stretched, frequency chirped pulse.

Journal Articles

Feasibility study on particle flowability evaluation in simplified MOX pellet fabrication process using vibrating tube method

Ishii, Katsunori; Suzuki, Masahiro; Yamamoto, Takuma; Kihara, Yoshiyuki; Yasuda, Masatoshi*; Matsusaka, Shuji*

Funtai Kogakkai-Shi, 45(5), p.290 - 296, 2008/05

Particle flowability test using a vibrating tube with a tapered end was carried out to evaluate the applicability of this method to the analysis of MOX particles for nuclear fuel pellet fabrication. In this experiment, zirconia particles were used as model particles, which are less than several hundred micrometers in diameter. The sample particles were prepared by mixing the particles with different sizes, whose shape and surface state were changed by a mechanical treatment. The experimental results showed that the removal of smaller particles is more effective than the mechanical surface treatment to improve the flowability. Furthermore, it was found that the vibrating tube method can identify the difference of the particle flowability more easily and clearly than the method based on Carr's flowability index.

Journal Articles

Simultaneous proton and X-ray imaging with femtosecond intense laser driven plasma source

Orimo, Satoshi; Nishiuchi, Mamiko; Daido, Hiroyuki; Yogo, Akifumi; Ogura, Koichi; Sagisaka, Akito; Li, Z.*; Pirozhkov, A. S.; Mori, Michiaki; Kiriyama, Hiromitsu; et al.

Japanese Journal of Applied Physics, Part 1, 46(9A), p.5853 - 5858, 2007/09

 Times Cited Count:16 Percentile:53.23(Physics, Applied)

A laser-driven proton beam with a maximum energy of a few MeV is stably obtained using an ultra-short and high-intensity Titanium Sapphire laser. At the same time, keV X-ray is also generated at almost the same place where protons are emitted. Here, we show the successful demonstration of simultaneous proton and X-ray projection images of a test sample placed close to the source with a resolution of $$sim$$10$$mu$$m, which is determined from the source sizes. Although the experimental configuration is very simple, the simultaneity is better than a few hundreds of ps. A CR-39 track detector and imaging plate, which are placed as close as possible to the CR-39, are used as detectors of protons and X-ray. The technique is applicable to the precise observation of microstructures.

Journal Articles

High-energy, high-contrast, multiterawatt laser pulses by optical parametric chirped-pulse amplification

Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Yamamoto, Yoichi*; Tanoue, Manabu*; Akutsu, Atsushi; Shimomura, Takuya*; Kondo, Shuji; Kanazawa, Shuhei; Daido, Hiroyuki; et al.

Optics Letters, 32(16), p.2315 - 2317, 2007/08

 Times Cited Count:49 Percentile:87.61(Optics)

We describe a compact, reliable, high-power, and high-contrast noncollinear optical parametric chirped-pulse amplifier system. With a broadband Ti:sapphire oscillator and grating-based stretching and compression, the chirped pulses are amplified from 0.1 nJ to 122 mJ in type-I $$beta$$-barium borate optical parametric chirped pulse amplifiers with a total gain of over 10$$^{9}$$ at 10 Hz repetition rate. Pulse compression down to 19-fs duration achieved after amplification indicates a peak power of 3.2 TW at an average power of 0.62 W. The pre-pulse contrast is measured to be less than 10$$^{-8}$$ on picosecond timescales.

Journal Articles

Imaging of the Mozumi-Sukenobe fault, Hida district, central Japan, by the seismic reflection method

Ito, Tanio*; Tsumura, Noriko*; Takeuchi, Akira*; Ishimaru, Tsuneari; Takami, Akira*; Ikawa, Hidemasa*; Komada, Nozomi*; Yamamoto, Shuji*; Kikuchi, Shinsuke*; Miyauchi, Takahiro*; et al.

Geodynamics of Atotsugawa Fault System, p.17 - 24, 2007/00

no abstracts in English

Journal Articles

Development of laser driven proton sources and their applications

Daido, Hiroyuki; Sagisaka, Akito; Ogura, Koichi; Orimo, Satoshi; Nishiuchi, Mamiko; Mori, Michiaki; Ma, J.-L.; Pirozhkov, A. S.; Kiriyama, Hiromitsu; Kanazawa, Shuhei; et al.

Proceedings of 7th Pacific Rim Conference on Lasers and Electro-Optics (CLEO-PR 2007) (CD-ROM), p.77 - 79, 2007/00

We are developing a proton accelerator using an intense lasers with a focused intensity of $$>$$ 10$$^{17}$$ W/cm$$^{2}$$. To monitor proton energy spectra as well as plasma parameters at each laser shot, we are using real time detectors. The proton energy of MeV is stably obtained for applications.

Journal Articles

Reaction, transport and settling behavior of lead-bismuth eutectic in flowing liquid sodium

Miyahara, Shinya; Ohno, Shuji; Yamamoto, Nobuhiro; Saito, Junichi; Hirabayashi, Masaru

Proceedings of 14th International Conference on Nuclear Engineering (ICONE-14) (CD-ROM), 7 Pages, 2006/07

The experimental study has been carried out to investigate reaction, transport and settling behavior of lead-bismuth eutectic (LBE) in flowing liquid sodium. In the test, 168 g of LBE were poured into flowing sodium from the top of a vertical-type sodium loop which contained 23.2 kg of sodium. The initial temperature of LBE and sodium was 673 K. The flow rate and the maximum velocity of sodium in the loop were controlled and measured at 20 dm$$^{3}$$/min and 1 m/sec, respectively, using an electro-magnetic pump and an electro-magnetic flow meter. The sodium loop has a settling chamber at the lower part to investigate the concentration decrease behavior of solid particle reaction products in the sodium due to the settling effect. The concentration was measured by sodium sampling from the 11 positions of the loop during the experiment and its post-test chemical analysis. The temperature changes at the various parts of the loop were also measured during the experiment by thermo-couples attached on the outer surface of the loop. Ultrasonic detectors were attached on the outer surface of the loop below the position of a LBE pour nozzle to demonstrate the utility as a leak detector.

Journal Articles

Measurements of neutron-capture cross sections of radioactive nuclides through high-energy $$gamma$$-ray spectroscopic studies

Furutaka, Kazuyoshi; Harada, Hideo; Nakamura, Shoji; Sakane, Hitoshi; Yamana, Hajimu*; Fujii, Toshiyuki*; Yamamoto, Shuji*; Hori, Junichi*; Igashira, Masayuki*; Osaki, Toshiro*; et al.

KURRI Progress Report 2004, P. 16, 2005/09

This report describes the studies done through spectroscopic method of high-energy $$gamma$$ ray to determine neutron capture cross sections of radioactive nuclides, in FY2004 at the Research Reactor Institute, Kyoto University. The following three items are described. (1) Development of a method to determine thermal neutron capture cross sections by prompt $$gamma$$-ray measurements, (2) Evaluation of a large BGO detector system as a total-energy detector, and (3) neutron capture cross-section measurements by TOF method.

46 (Records 1-20 displayed on this page)