Refine your search:     
Report No.
Search Results: Records 1-20 displayed on this page of 78

Presentation/Publication Type

Initialising ...


Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...


Initialising ...


Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

JAEA Reports

Differential pressure rise event for filters of HTTR primary helium gas circulators, 1; Investigation of differential pressure rise event

Nemoto, Takahiro; Arakawa, Ryoki; Kawakami, Satoru; Nagasumi, Satoru; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; Furusawa, Takayuki; Inoi, Hiroyuki; et al.

JAEA-Technology 2023-005, 33 Pages, 2023/05


During shut down of the HTTR (High Temperature engineering Test Reactor) RS-14 cycle, an increasing trend of filter differential pressure for the helium gas circulator was observed. In order to investigate this phenomenon, the blower of the primary helium purification system was disassembled and inspected. As a result, it is clear that the silicon oil mist entered into the primary coolant due to the deterioration of the charcoal filter performance. The replacement and further investigation of the filter are planning to prevent the reoccurrence of the same phenomenon in the future.

Journal Articles

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

 Times Cited Count:1 Percentile:58.67(Nuclear Science & Technology)

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Journal Articles

Improving the safety of the high temperature gas-cooled reactor "HTTR" based on Japan's new regulatory requirements

Hamamoto, Shimpei; Shimizu, Atsushi; Inoi, Hiroyuki; Tochio, Daisuke; Homma, Fumitaka; Sawahata, Hiroaki; Sekita, Kenji; Watanabe, Shuji; Furusawa, Takayuki; Iigaki, Kazuhiko; et al.

Nuclear Engineering and Design, 388, p.111642_1 - 111642_11, 2022/03

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Following the Fukushima Daiichi Nuclear Power Plant accident in 2011, the Japan Atomic Energy Agency adapted High-Temperature engineering Test Reactor (HTTR) to meet the new regulatory requirements that began in December 2013. The safety and seismic classifications of the existing structures, systems, and components were discussed to reflect insights regarding High Temperature Gas-cooled Reactors (HTGRs) that were acquired through various HTTR safety tests. Structures, systems, and components that are subject to protection have been defined, and countermeasures to manage internal and external hazards that affect safety functions have been strengthened. Additionally, measures are in place to control accidents that may cause large amounts of radioactive material to be released, as a beyond design based accident. The Nuclear Regulatory Commission rigorously and appropriately reviewed this approach for compliance with the new regulatory requirements. After nine amendments, the application to modify the HTTR's installation license that was submitted in November 2014 was approved in June 2020. This response shows that facilities can reasonably be designed to meet the enhanced regulatory requirements, if they reflect the characteristics of HTGRs. We believe that we have established a reference for future development of HTGR.

Journal Articles

Structures of magnetic excitations in the spin-$$frac{1}{2}$$ kagome-lattice antiferromagnets Cs$$_{2}$$Cu$$_{3}$$SnF$$_{12}$$ and Rb$$_{2}$$Cu$$_{3}$$SnF$$_{12}$$

Saito, Mutsuki*; Takagishi, Ryunosuke*; Kurita, Nubuyuki*; Watanabe, Masari*; Tanaka, Hidekazu*; Nomura, Ryuji*; Fukumoto, Yoshiyuki*; Ikeuchi, Kazuhiko*; Kajimoto, Ryoichi

Physical Review B, 105(6), p.064424_1 - 064424_15, 2022/02

 Times Cited Count:4 Percentile:85.24(Materials Science, Multidisciplinary)

Journal Articles

Deexcitation dynamics of muonic atoms revealed by high-precision spectroscopy of electronic $$K$$ X rays

Okumura, Takuma*; Azuma, Toshiyuki*; Bennet, D. A.*; Caradonna, P.*; Chiu, I. H.*; Doriese, W. B.*; Durkin, M. S.*; Fowler, J. W.*; Gard, J. D.*; Hashimoto, Tadashi; et al.

Physical Review Letters, 127(5), p.053001_1 - 053001_7, 2021/07

 Times Cited Count:5 Percentile:52.75(Physics, Multidisciplinary)

We observed electronic $$K$$X rays emitted from muonic iron atoms using a superconducting transition-edge-type sensor microcalorimeter. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic $$K$$$$alpha$$ and $$K$$$$beta$$ X rays together with the hypersatellite $$K$$$$alpha$$ X rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the $$L$$-shell electrons, accompanied by electron side-feeding. Assisted by a simulation, this data clearly reveals the electronic $$K$$- and $$L$$-shell hole production and their temporal evolution during the muon cascade process.

JAEA Reports

Data of radon measurement in underground facilities of Mizunami Underground Research Laboratory

Aoki, Katsunori; Yamanaka, Hiroki*; Watanabe, Kazuhiko*; Sugihara, Kozo

JAEA-Data/Code 2020-018, 45 Pages, 2021/02


Mizunami Underground Research Laboratory (MIU) Project is pursued by Japan Atomic Energy Agency (JAEA) in the crystalline host rock (granite) as a part of geoscientific study of JAEA, and underground facilities of MIU are constructed down to 500m blow the ground surface. As small amount of Uranium is normally contained in granite, high concentration of radon is sometimes detected in the air of the underground facilities constructed in granitic rocks depending on their ventilation conditions. Radon concentrations in underground facilities of MIU have been measured according to the excavation progress of underground facilities or the change of ventilation system. It is recognized that the data obtained by the actual measurement of radon concentration in such underground facilities are rare and valuable. This repot summarizes the measured data from fiscal 2010 to fiscal 2020, together with the information of ventilation conditions and air temperature which affect radon concentrations in underground facilities. The variation of the equilibrium factors of radon is also examined with the actually measured data. As a result, it has been found that radon concentration in the drift is high in summer and low in winter according to the natural ventilation caused by the seasonal temperature difference between in and out of the underground facilities. Furthermore, the temporary increase in the equilibrium factor of radon in the drift at the start of ventilation is supposed to be due to the aerosol increase by the ventilation flow, such as the dust blown up.

Journal Articles

Machine status monitoring system for J-PARC RCS

Takahashi, Hiroki; Sawabe, Yuki*; Watanabe, Kazuhiko*

Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.275 - 279, 2020/09

The amount of monitor value (operation information) tends to increase, because of the increase of accelerator components, or in order to realize the safety and the stable operation. Then, an enormous volume of operation data increases the possibility of occurrence of erroneous operation such as overlooking of monitor value and etc. In order to ensure the safe and stable operation of the J-PARC accelerator, the occurrence of such human error is alarming. Therefore, for the purpose of operation support, we started designing and producing a system that monitors the machine status and detects alarm status from 2017. First, for Linac, we designed and produced a function to detect the alarm status based on the set value. Next, this function was applied to the machine status monitoring system for RCS. In addition, we are designing and developing functions to detect the alarm status based on the reference value or fixed value, for the purpose of detecting setting errors due to human error. In this paper, the current status and future plans of machine status monitoring system for J-PARC RCS are presented.

Journal Articles

Result of seismic motion observation from ground surface to 500m depth at Mizunami Underground Research Laboratory and its detailed analysis

Matsui, Hiroya; Watanabe, Kazuhiko*; Mikake, Shinichiro; Niimi, Katsuyuki*; Kobayashi, Shinji*; Toguri, Satohito*

Dai-47-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (Internet), p.293 - 298, 2020/01

Japan Atomic Energy Agency has been observed seismic motions induced by earthquakes, at ground surface, galleries at 100m, 300m and 500m depth of Mizunami underground research laboratory for over 10 years. The results suggested that the amplitude of the seismic motion decreases with depth as the previous study on crystalline rock at Kamaishi mine indicated. Detailed analysis on the observed seismic motions shows that the Fourier amplitude and the phase difference of the earthquake occurred near epicenter correspond with the one calculated by one-dimensional multiple reflection theory.

Journal Articles

Progress of criticality control study on fuel debris by Japan Atomic Energy Agency to support Secretariat of Nuclear Regulation Authority

Tonoike, Kotaro; Watanabe, Tomoaki; Gunji, Satoshi; Yamane, Yuichi; Nagaya, Yasunobu; Umeda, Miki; Izawa, Kazuhiko; Ogawa, Kazuhiko

Proceedings of 11th International Conference on Nuclear Criticality Safety (ICNC 2019) (Internet), 9 Pages, 2019/09

Criticality control of the fuel debris in the Fukushima Daiichi Nuclear Power Station would be a risk-informed control to mitigate consequences of criticality events, instead of a deterministic control to prevent such events. The Nuclear Regulation Authority of Japan has administrated a research and development program to tackle this challenge since 2014. The Nuclear Safety Research Center of Japan Atomic Energy Agency, commissioned by the authority, is conducting activities such as computations of criticality characteristics of the fuel debris, development of a criticality analysis code, preparation of criticality experiments, and development of a criticality risk analysis method.

Journal Articles

Present status of personnel protection system at J-PARC

Kikuzawa, Nobuhiro; Niki, Kazuaki*; Yamamoto, Noboru*; Hayashi, Naoki; Adachi, Masatoshi*; Watanabe, Kazuhiko*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.877 - 880, 2019/07

Interlock system of J-PARC is classified into a personnel protection system (PPS) for human safety and a machine protection system (MPS) for protecting equipment. The PPS of the J-PARC accelerator started from the operation at Linac in 2006 and was completed by the MR operation in 2008. In the next 10 years, some improvements have been made, such as updating video monitoring systems and establishing new interlocks. In addition to describing recent operations including these updatings, this paper reports the current status of inspections and maintenance conducted to maintain and improve reliability.

Journal Articles

Examination of evaluation method for fault activity based on morphological observation of fault planes

Tanaka, Yoshihiro*; Kametaka, Masao*; Okazaki, Kazuhiko*; Suzuki, Kazushige*; Seshimo, Kazuyoshi; Aoki, Kazuhiro; Shimada, Koji; Watanabe, Takahiro; Nakayama, Kazuhiko

Oyo Chishitsu, 59(1), p.13 - 27, 2018/04

This paper aims to develop a methodology for understanding the fault activity by observing exposed fault planes without covering younger strata. Based on purpose, faults developed in relatively homogeneous rocks such granitic types are investigated as follows; Gosuke Dam upstream outcrop of Gosukebashi Fault and Funasaka-nishi outcrop of Rokkou Fault were selected for the study of an active fault; and K-3 outcrop of Rokkou Houraikyo Fault was chosen for a non-active fault.

Journal Articles

Supervision and alarm system for J-PARC Linac and RCS

Takahashi, Hiroki; Sawabe, Yuki; Watanabe, Kazuhiko*; Kawase, Masato*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1151 - 1154, 2017/12

The amount of monitor value tends to increase, because of the increase of accelerator components, or in order to realize the safety and the stable operation. Then, an enormous volume of operation data increases the possibility of occurrence of erroneous operation such as overlooking of monitor value and etc. Then, we started to develop a system to supervise the state of the accelerator and to inform operators of abnormality early. As an initial system, we developed a system to supervise the status of Linac DTQ power supplies and etc. In this initial system, first, the function was created to make the normal range (upper and lower limit values) with reference to the current setting value. Next, the function to inform the alarm condition when the monitor value becomes outside of the normal range was realized. This function is an important function in the initial system. By this realization, we obtained the prospect of development of supervision and alarm system.

Journal Articles

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 3; Neutron devices and computational and sample environments

Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.

Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09

Neutron devices such as neutron detectors, optical devices including supermirror devices and $$^{3}$$He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.

Journal Articles

Simultaneous analysis of silicon and boron dissolved in water by combination of electrodialytic salt removal and ion-exclusion chromatography with corona charged aerosol detection

Mori, Masanobu*; Sagara, Katsuya*; Arai, Kaori*; Nakatani, Nobutake*; Ohira, Shinichi*; Toda, Kei*; Itabashi, Hideyuki*; Kozaki, Daisuke*; Sugo, Yumi; Watanabe, Shigeki; et al.

Journal of Chromatography A, 1431, p.131 - 137, 2016/01

 Times Cited Count:10 Percentile:44.73(Biochemical Research Methods)

Journal Articles

Progress in long-pulse production of powerful negative ion beams for JT-60SA and ITER

Kojima, Atsushi; Umeda, Naotaka; Hanada, Masaya; Yoshida, Masafumi; Kashiwagi, Mieko; Tobari, Hiroyuki; Watanabe, Kazuhiro; Akino, Noboru; Komata, Masao; Mogaki, Kazuhiko; et al.

Nuclear Fusion, 55(6), p.063006_1 - 063006_9, 2015/06

 Times Cited Count:37 Percentile:89.49(Physics, Fluids & Plasmas)

Significant progresses in the extension of pulse durations of powerful negative ion beams have been made to realize the neutral beam injectors for JT-60SA and ITER. In order to overcome common issues of the long pulse production/acceleration of negative ion beams in JT-60SA and ITER, the new technologies have been developed in the JT-60SA ion source and the MeV accelerator in Japan Atomic Energy Agency. As for the long pulse production of high-current negative ions for JT-60SA ion source, the pulse durations have been successfully increased from 30 s at 13 A on JT-60U to 100 s at 15 A by modifying the JT-60SA ion source, which satisfies the required pulse duration of 100 s and 70% of the rated beam current for JT-60SA. This progress was based on the R&D efforts for the temperature control of the plasma grid and uniform negative ion productions with the modified tent-shaped filter field configuration. Moreover, the each parameter of the required beam energy, current and pulse has been achieved individually by these R&D efforts. The developed techniques are useful to design the ITER ion source because the sustainment of the cesium coverage in large extraction area is one of the common issues between JT-60SA and ITER. As for the long pulse acceleration of high power density beams in the MeV accelerator for ITER, the pulse duration of MeV-class negative ion beams has been extended by more than 2 orders of magnitude by modifying the extraction grid with a high cooling capability and a high-transmission of negative ions. A long pulse acceleration of 60 s has been achieved at 70 MW/m$$^{2}$$ (683 keV, 100 A/m$$^{2}$$) which has reached to the power density of JT-60SA level of 65 MW/m$$^{2}$$.

JAEA Reports

Mizunami Underground Research Laboratory Project; Compilation of results of geological investigation at the -500m stage

Kawamoto, Koji; Murakami, Hiroaki; Ishibashi, Masayuki; Sasao, Eiji; Watanabe, Kazuhiko; Mikake, Shinichiro; Ikeda, Koki

JAEA-Data/Code 2014-014, 27 Pages, 2014/08


This document presents the data of geological investigations at the -500m stage of the MIU from the 2011 fiscal year to the 2013 fiscal year. At the -500m stage of the MIU, although the Cretaceous Toki granite is distributed, pegmatite, aplite and lampropyre dike are distributed partially.

JAEA Reports

Results of pilot borehole investigation in -500m access/research gallery-south (12MI32 borehole)

Kawamoto, Koji; Kuroiwa, Hiroshi; Yamada, Nobuto; Onuki, Kenji; Omori, Kazuaki; Takeuchi, Ryuji; Ogata, Nobuhisa; Omori, Masaki; Watanabe, Kazuhiko

JAEA-Technology 2014-011, 92 Pages, 2014/07


This document summarizes the data of pilot boreholes (12MI32) in the -500m Access/Research Gallery-South. The geological, hydraulic and geochemical data were obtained. In addition, groundwater monitoring system was installed to observe the groundwater pressure in initial condition and change during the excavation of gallery. The results of investigation, biotite granite with medium to coarse-grained equigranular texture are characterized. Rock mass classification is B from CM class. Minor fault with fault breccia are observed around 48.90mabh. However, S200_13 fault and IF_SB3_13_3 fault (that were presumed by an original model) were not observed. Density of fracture is large in the section of 40.00 to 80.00mabh. Water inflow was a maximum of 600 L/min in 78.83mabh. Permeability ranges from 2.0E-9 to 1.5E-08m/sec at the zone with low inflow, from 1.1E-05 to 1.6E-05m/sec at the zone with high inflow, respectively. Groundwater chemistry is rich in Na and Cl ion.

Journal Articles

Progress in development and design of the neutral beam injector for JT-60SA

Hanada, Masaya; Kojima, Atsushi; Tanaka, Yutaka; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; Tobari, Hiroyuki; Umeda, Naotaka; Akino, Noboru; et al.

Fusion Engineering and Design, 86(6-8), p.835 - 838, 2011/10

 Times Cited Count:10 Percentile:62.29(Nuclear Science & Technology)

Neutral beam (NB) injectors for JT-60 Super Advanced (JT-60SA) have been designed and developed. Twelve positive-ion-based and one negative-ion-based NB injectors are allocated to inject 30 MW D$$^{0}$$ beams in total for 100 s. Each of the positive-ion-based NB injector is designed to inject 1.7 MW for 100s at 85 keV. A part of the power supplies and magnetic shield utilized on JT-60U are upgraded and reused on JT-60SA. To realize the negative-ion-based NB injector for JT-60SA where the injection of 500 keV, 10 MW D$$^{0}$$ beams for 100s is required, R&Ds of the negative ion source have been carried out. High-energy negative ion beams of 490-500 keV have been successfully produced at a beam current of 1-2.8 A through 20% of the total ion extraction area, by improving voltage holding capability of the ion source. This is the first demonstration of a high-current negative ion acceleration of $$>$$1 A to 500 keV. The design of the power supplies and the beamline is also in progress. The procurement of the acceleration power supply starts in 2010.

Journal Articles

Development of the JT-60SA Neutral Beam Injectors

Hanada, Masaya; Kojima, Atsushi; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; Tobari, Hiroyuki; Umeda, Naotaka; Akino, Noboru; Kazawa, Minoru; et al.

AIP Conference Proceedings 1390, p.536 - 544, 2011/09

 Times Cited Count:7 Percentile:84.85

no abstracts in English

Journal Articles

Achievement of 500 keV negative ion beam acceleration on JT-60U negative-ion-based neutral beam injector

Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.

Nuclear Fusion, 51(8), p.083049_1 - 083049_8, 2011/08

 Times Cited Count:49 Percentile:88.37(Physics, Fluids & Plasmas)

Hydrogen negative ion beams of 490 keV, 3 A and 510 keV, 1 A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 2 m$$^{2}$$ for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m$$^{2}$$). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60SA and ITER.

78 (Records 1-20 displayed on this page)