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Journal Articles

Development of an iron(II) complex exhibiting thermal- and photoinduced double proton-transfer-coupled spin transition in a short hydrogen bond

Nakanishi, Takumi*; Hori, Yuta*; Shigeta, Yasuteru*; Sato, Hiroyasu*; Kiyanagi, Ryoji; Munakata, Koji*; Ohara, Takashi; Okazawa, Atsushi*; Shimada, Rintaro*; Sakamoto, Akira*; et al.

Journal of the American Chemical Society, 145(35), p.19177 - 19181, 2023/08

JAEA Reports

Study on the evaluation method to determine the radioactivity concentration in radioactive waste on Oarai Research and Development Institute (FY2020)

Asakura, Kazuki; Shimomura, Yusuke; Donomae, Yasushi; Abe, Kazuyuki; Kitamura, Ryoichi; Miyakoshi, Hiroyuki; Takamatsu, Misao; Sakamoto, Naoki; Isozaki, Ryosuke; Onishi, Takashi; et al.

JAEA-Review 2021-020, 42 Pages, 2021/10

JAEA-Review-2021-020.pdf:2.95MB

The disposal of radioactive waste from the research facility need to calculate from the radioactivity concentration that based on variously nuclear fuels and materials. In Japan Atomic Energy Agency Oarai Research and Development Institute, the study on considering disposal is being advanced among the facilities which generate radioactive waste as well as the facilities which process radioactive waste. This report summarizes a study result in FY2020 about the evaluation method to determine the radioactivity concentration in radioactive waste on Oarai Research and Development Institute.

Journal Articles

Mapping measurement for beam energy position monitor system for RIKEN superconducting acceleration cavity

Watanabe, Tamaki*; Toyama, Takeshi*; Hanamura, Kotoku*; Imao, Hiroshi*; Kamigaito, Osamu*; Kamoshida, Atsushi*; Kawachi, Toshihiko*; Koyama, Ryo*; Sakamoto, Naruhiko*; Fukunishi, Nobuhisa*; et al.

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1105 - 1108, 2019/07

Upgrades for the RIKEN heavy-ion linac (RILAC) involving a new superconducting linac (SRILAC) are currently underway at the RIKEN radioactive isotope beam factory (RIBF). It is crucially important to develop nondestructive beam measurement diagnostics. We have developed a beam energy position monitor (BEPM) system which can measure not only the beam position but also the beam energy simultaneously by measuring the time of flight of the beam. We fabricated 11 BEPMs and completed the position calibration to obtain the sensitivity and offset for each BEPMs. The position accuracy has been achieved to be less than $$pm$$ 0.1 mm by using the mapping measurement.

Journal Articles

Simulation of fluidity, dispersion and mass transfer in an annular centrifugal contactor

Sano, Yuichi; Sakamoto, Atsushi; Takeuchi, Masayuki; Misumi, Ryuta*; Kunii, Kanako*; Todoroki, Kei*; Nishi, Kazuhiko*; Kaminoyama, Meguru*

Kagaku Kogaku Rombunshu, 44(6), p.335 - 340, 2018/11

Concerning an annular centrifugal contactor which has high throughput and separation performance, the effect of operational condition on fluidic and dispersion behavior, which are important to improve the contactor performance, was investigated by computational fluid dynamics (CFD) analysis based on the turbulence model, and the calculated results were validated by experimental data. The liquid phase in the annular zone was gradually divided into two regions vertically with increasing the rotor speed and decreasing the flowrate, and the liquid flow moved toward the center of the housing bottom was generated in the lower annular zone under any operational condition. The droplet size of the dispersed phase in the annular zone decreased with increasing the rotor speed and decreasing the flowrate. These calculation results showed a good agreement with experimental data. The CFD analysis considering mass transfer between aqueous and organic phases was also attempted, and it was confirmed that the change of extraction performance with the rotor speed showed the same tendency as the experimental result.

Journal Articles

Flow behavior in annular centrifugal extractors with different vessel sizes

Misumi, Ryuta*; Todoroki, Kei*; Kunii, Kanako*; Nishi, Kazuhiko*; Kaminoyama, Meguru*; Sano, Yuichi; Sakamoto, Atsushi; Takeuchi, Masayuki

Kagaku Kogaku Rombunshu, 44(5), p.285 - 291, 2018/09

Annular centrifugal extractors have been anticipated for use as extractors in spent nuclear fuel recycling. The extraction rate and the liquid-liquid dispersion are related to the flow pattern in the vessel. However, no study has clarified flow patterns in vessels of various scales. For this study, flow pattern characteristics are quantified for extractors of two scales. An extractor has a mixing zone around the vessel bottom and a separation zone in the cylindrical rotor. For this experiment, distilled water was fed into the vessel. Flow behavior in the mixing zone was observed from a side view using a digital video camera at various rotor speeds and supply flow rates for extractors of two scales. In some cases, the liquid horizontal velocity vectors in the mixing zone were measured using particle image velocimetry. Results demonstrate that flow behaviors in the mixing zone in both scales of extractors are classifiable as three types, changing with operational conditions: Type A, Type B, and a Transition regime. For the Type A state, the mixing zone is fully filled with liquid from the vessel bottom up to the lower edge of the rotor. In the Type B state, the zone with existing liquid is vertically divisible into two regions. Lower rotor speeds and higher flow rates tend to produce Type A state flow behavior. The boundary operational condition between Type A and the Transition regime are correlated with the normalized supply flow rate and pumping capacity of the rotor, which is evaluated from liquid surface level in a rotor formed by centrifugal force. Furthermore, the fluid velocity in the mixing zone is roughly proportional to the rotor surface circumferential speed irrespective of the vessel scale.

Journal Articles

Development of beam energy position monitor system for RIKEN superconducting acceleration cavity

Watanabe, Tamaki*; Imao, Hiroshi*; Kamigaito, Osamu*; Sakamoto, Naruhiko*; Fukunishi, Nobuhisa*; Fujimaki, Masaki*; Yamada, Kazunari*; Watanabe, Yutaka*; Koyama, Ryo*; Toyama, Takeshi*; et al.

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.49 - 54, 2018/08

no abstracts in English

Journal Articles

Rotor speed and supply flow rate effects on flow behavior in an annular centrifugal extractor

Misumi, Ryuta*; Kunii, Kanako*; Todoroki, Kei*; Nishi, Kazuhiko*; Kaminoyama, Meguru*; Sano, Yuichi; Sakamoto, Atsushi; Takeuchi, Masayuki

Kagaku Kogaku Rombunshu, 44(3), p.135 - 141, 2018/05

 Times Cited Count:0 Percentile:4.93(Engineering, Chemical)

Annular centrifugal extractors have been used in spent nuclear fuel reprocessing, but the relation between the extraction rate and flow pattern in the vessel remains unclear. This study quantifies characteristics of the flow pattern to clarify this relation. An extractor produces a mixing zone around the vessel bottom and a separation zone in the rotor. The horizontal velocity of the liquid in the mixing zone was measured using particle image velocimetry at various rotor speeds and supply flow rates. Flow behaviors in the mixing zone are of three types, changing with operational conditions: Type A, Type B, and a transition regime. At lower rotor speeds and high supply flow rates, the mixing zone is fully filled with liquid from the vessel bottom up to the lower edge of the rotor: the Type A flow state. At high rotor speeds and low supply flow rates, the zone with existing liquid is vertically divisible into two regions: near the vanes and around the bottom of the rotor, which is the Type B flow state. A transition regime is also observed between Type A and Type B state. In each region surrounding the two vanes on the vessel bottom and the vessel wall, the liquid flowed in the direction of rotor rotation along the vessel wall. Liquid flow altered by the vane flowed toward the center of vessel bottom. The liquid then entered the separation zone through the orifice at the rotor bottom. For the Type A state, the horizontal velocity distribution was roughly proportional to the rotor speed. For the Type B state, the horizontal velocities around the vessel bottom were lower than those of Type A and were not proportional to the rotor speed. Presumably, the liquid fed into the vessel went directly to the rotor instead of passing between the two vanes attached to the vessel bottom.

Journal Articles

Progress of divertor simulation research toward the realization of detached plasma using a large tandem mirror device

Nakashima, Yosuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Oki, Kensuke*; Sakamoto, Mizuki*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; Imai, Tsuyoshi*; et al.

Journal of Nuclear Materials, 463, p.537 - 540, 2015/08

 Times Cited Count:18 Percentile:82.74(Materials Science, Multidisciplinary)

Journal Articles

Development of divertor simulation research in the GAMMA 10/PDX tandem mirror

Nakashima, Yosuke*; Sakamoto, Mizuki*; Yoshikawa, Masayuki*; Oki, Kensuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; et al.

Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 8 Pages, 2014/10

Journal Articles

Development of a high power gyrotron operating at 28 and 35 GHz

Kariya, Tsuyoshi*; Minami, Ryutaro*; Imai, Tsuyoshi*; Eguchi, Taku*; Sakamoto, Keishi; Mitsunaka, Yoshika*; Numakura, Tomoharu*; Endo, Yoichi*

Plasma and Fusion Research (Internet), 8, p.1205107_1 - 1205107_2, 2013/10

Journal Articles

Development of multi-purpose MW gyrotrons for fusion devices

Minami, Ryutaro*; Kariya, Tsuyoshi*; Imai, Tsuyoshi*; Numakura, Tomoharu*; Endo, Yoichi*; Nakabayashi, Hidetaka*; Eguchi, Taku*; Shimozuma, Takashi*; Kubo, Shin*; Yoshimura, Yasuo*; et al.

Nuclear Fusion, 53(6), p.063003_1 - 063003_7, 2013/06

Journal Articles

Development of multi-purpose MW gyrotrons for fusion devices

Minami, Ryutaro*; Kariya, Tsuyoshi*; Imai, Tsuyoshi*; Numakura, Tomoharu*; Endo, Yoichi*; Nakabayashi, Hidetaka*; Eguchi, Taku*; Shimozuma, Takashi*; Kubo, Shin*; Yoshimura, Yasuo*; et al.

Nuclear Fusion, 53(6), p.063003_1 - 063003_7, 2013/06

 Times Cited Count:12 Percentile:47.58(Physics, Fluids & Plasmas)

Journal Articles

Development of a resonant laser ionization gas cell for high-energy, short-lived nuclei

Sonoda, Tetsu*; Wada, Michiharu*; Tomita, Hideki*; Sakamoto, Chika*; Takatsuka, Takaaki*; Furukawa, Takeshi*; Iimura, Hideki; Ito, Yuta*; Kubo, Toshiyuki*; Matsuo, Yukari*; et al.

Nuclear Instruments and Methods in Physics Research B, 295, p.1 - 10, 2013/01

 Times Cited Count:20 Percentile:83.94(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Momentum transport studies from multi-machine comparisons

Yoshida, Maiko; Kaye, S.*; Rice, J.*; Solomon, W.*; Tala, T.*; Bell, R. E.*; Burrell, K. H.*; Ferreira, J.*; Kamada, Yutaka; McDonald, D. C.*; et al.

Nuclear Fusion, 52(12), p.123005_1 - 123005_11, 2012/11

 Times Cited Count:16 Percentile:56.93(Physics, Fluids & Plasmas)

The purpose of this study is to find a common feature on momentum transport coefficients including diffusive and non-diffusive terms in all machines. The momentum database enables us to assess a parametric dependency of momentum transport in a wider range of dimensionless parameters related to transport. Such observation will contribute to make a scaling/modeling on momentum transport for future devices like ITER and DEMO. On the other hand, the investigation of a difference in observation by comparing the experimental conditions will give a useful information to realize what plasma parameter is the key for the momentum transport coefficients.

Journal Articles

Modifications to the edge radial electric field by angular momentum injection in JT-60U and their implication for pedestal transport

Kamiya, Kensaku; Honda, Mitsuru; Miyato, Naoaki; Urano, Hajime; Yoshida, Maiko; Sakamoto, Yoshiteru; Matsunaga, Go; Oyama, Naoyuki; Koide, Yoshihiko; Kamada, Yutaka; et al.

Nuclear Fusion, 52(11), p.114010_1 - 114010_12, 2012/10

 Times Cited Count:10 Percentile:40.96(Physics, Fluids & Plasmas)

Depending on the direction of the external tangential momentum input, substantial changes in not only toroidal but also poloidal flows for the carbon impurity ions are observed at around the $$E$$$$_{r}$$-well region. The shear in the edge $$E$$$$_{r}$$ becomes wider in the co-NBI case, while the edge $$E$$$$_{r}$$-well becomes deeper in the counter-NBI case.

Journal Articles

Electronic configuration of Mn ions in the $$pi$$-$$d$$ molecular ferromagnetic $$beta$$-Mn phthalocyanine studied by soft X-ray magnetic circular dichroism

Kataoka, Takashi*; Sakamoto, Yuta*; Yamazaki, Yo*; Singh, V. R.*; Fujimori, Atsushi*; Takeda, Yukiharu; Okochi, Takuo*; Fujimori, Shinichi; Okane, Tetsuo; Saito, Yuji; et al.

Solid State Communications, 152(9), p.806 - 809, 2012/05

 Times Cited Count:19 Percentile:60.56(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Core and edge toroidal rotation study in JT-60U

Yoshida, Maiko; Sakamoto, Yoshiteru; Honda, Mitsuru; Kamada, Yutaka; Takenaga, Hidenobu; Oyama, Naoyuki; Urano, Hajime; JT-60 Team

Nuclear Fusion, 52(2), p.023024_1 - 023024_9, 2012/02

 Times Cited Count:13 Percentile:52.32(Physics, Fluids & Plasmas)

Relation between the toroidal rotation velocities in the core and edge regions has been investigated in H-mode plasmas with small external torque input from the viewpoint of momentum transport. The toroidal rotation velocity in the core region gradually varies on a timescale after a rapid change in the toroidal rotation velocity in the edge region at the L-H transition. In steady state, a linear correlation between the core- and edge-rotation is observed in H-mode plasmas when the ion pressure gradient is small. The rotation profiles with a large have been reproduced in the core region by adopting a residual stress term proposed in this paper. Parameter dependencies of the edge-rotation are investigated at a constant ripple loss power, ripple amplitude and the plasma current. A reduction in the CTR-rotation is observed with decreasing the ion temperature gradient. Here CTR refers in the counter-$$I$$$$_{rm P}$$ direction.

Journal Articles

Edge pedestal characteristics in JET and JT-60U tokamaks under variable toroidal field ripple

Urano, Hajime; Saibene, G.*; Oyama, Naoyuki; Parail, V.*; de Vries, P.*; Sartori, R.*; Kamada, Yutaka; Kamiya, Kensaku; Loarte, A.*; L$"o$nnroth, J.*; et al.

Nuclear Fusion, 51(11), p.113004_1 - 113004_10, 2011/11

 Times Cited Count:10 Percentile:41.11(Physics, Fluids & Plasmas)

The effect of TF ripple on the edge pedestal characteristics are examined in JET and JT-60U. By the installation of ferritic inserts, TF ripple was reduced from $$1%$$ to $$0.6%$$ in JT-60U. In JET, TF ripple was varied from $$0.1%$$ to $$1%$$ by feeding different currents to TF coils. The pedestal pressure was similar with reduced ripple in JT-60U. In JET, no clear difference of the pedestal characteristics was also observed. The edge toroidal rotation clearly decreased in counter direction by increased TF ripple. However, in JT-60U, the ELM frequency decreased by $$sim 20%$$ and the increased ELM loss power by $$30%$$ with reduced ripple. In JET, ELM frequency increases only slightly with increased TF ripple. From this inter-machine experiment, TF ripple less than $$1%$$ does not strongly affect the pedestal pressure. The effect of TF ripple on pedestal characteristics at lower collisionality close to ITER should be investigated as a next step study.

Journal Articles

Spatio-temporal structure of the edge radial electric field during H-mode in JT-60U

Kamiya, Kensaku; Sakamoto, Yoshiteru; Matsunaga, Go; Kojima, Atsushi; Urano, Hajime; Oyama, Naoyuki; Koide, Yoshihiko; Kamada, Yutaka; Ida, Katsumi*; Kurki-Suonio, T.*; et al.

Nuclear Fusion, 51(5), p.053009_1 - 053009_3, 2011/05

 Times Cited Count:13 Percentile:49.62(Physics, Fluids & Plasmas)

We revisited to measure the edge impurity ion dynamic with new CXRS in the hot ion H-mode regime at the high magnetic field having two steps transition where a jump of Ti gradient precedes a jump of impurity Vp. Two discrete phases with different magnitude of Er in the H-phase have been observed. One is the intermediate H-phase having a large Ti gradients without significant Vp of impurity species with moderate magnitude of Er, and the other is the complete H-phase characterized by a large Er.

Journal Articles

Characteristics and control of the Type I edge localized mode in JT-60U

Oyama, Naoyuki; Hayashi, Nobuhiko; Aiba, Nobuyuki; Isayama, Akihiko; Urano, Hajime; Sakamoto, Yoshiteru; Kamada, Yutaka; Takizuka, Tomonori; JT-60 Team

Nuclear Fusion, 51(3), p.033009_1 - 033009_9, 2011/03

 Times Cited Count:15 Percentile:54.27(Physics, Fluids & Plasmas)

Coherent density and temperature precursors have been observed before the collapse phase of the Type I ELM. The growth rate of the precursor is evaluated to be $$gamma/omega_{it A} sim 10^{-3}$$ for several edge pedestal conditions. From the phase delay between ECE signals measured at two toroidal locations and the frequency of the precursor, the toroidal mode number is evaluated as n = 8-10 or 14-16. It is found that the dominant n varies with each ELM under the same plasma condition. When the ratio of the pressure gradient inside the pedestal to the pressure gradient within the pedestal becomes large, larger reduction of ion temperature as well as wider ELM affected area has been observed. When the plasma near the top of the pedestal on the high-field side is heated by the electron cyclotron wave power of 1.57 MW, the normalized ELM energy loss was reduced by 33 %, together with the increase in the ELM frequency.

209 (Records 1-20 displayed on this page)