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Ishikawa, Akihisa; Koba, Yusuke*; Furuta, Takuya; Chang, W.*; Yonai, Shunsuke*; Matsumoto, Shinnosuke*; Hashimoto, Shintaro; Hirai, Yuta*; Sato, Tatsuhiko
Radiological Physics and Technology, 17(2), p.553 - 560, 2024/06
Sano, Naruto; Yamashita, Naoki; Watanabe, Masaya; Tsukada, Manabu*; Hoshino, Kazutoyo*; Hirai, Koki; Ikegami, Yuta*; Tashiro, Shinsuke; Yoshida, Ryoichiro; Hatakeyama, Yuichi; et al.
JAEA-Technology 2023-029, 36 Pages, 2024/03
At the Waste Safety Testing Facility (WASTEF), the gamma ray irradiation device "Gamma Cell 220" was relocated from the 4th Research Building of the Nuclear Science Research Institute in FY2019, and the use of gamma ray irradiation has begun. Initially, Fuel Cycle Safety Research Group, Fuel Cycle Safety Research Division, Nuclear Safety Research Center, Sector of Nuclear Safety Research and Emergency Preparedness, the owner of this device, conducted the tests as the main user, but since 2022, other users, including those outside the organization, have started using it. The gamma ray irradiation device "Gamma Cell 220" is manufactured by Nordion International Inc. in Canada. Since it was purchased in 1989, the built-in Co radiation source has been updated once, and safety research related to nuclear fuel cycles, etc. It is still used for this purpose to this day. This report summarizes the equipment overview of the gamma ray irradiation device "Gamma Cell 220", its permits and licenses at WASTEF, usage status, maintenance and inspection, and future prospects.
Chiera, N. M.*; Sato, Tetsuya; Eichler, R.*; Tomitsuka, Tomohiro; Asai, Masato; Adachi, Sadia*; Dressler, R.*; Hirose, Kentaro; Inoue, Hiroki*; Ito, Yuta; et al.
Angewandte Chemie; International Edition, 60(33), p.17871 - 17874, 2021/08
Times Cited Count:4 Percentile:22.30(Chemistry, Multidisciplinary)The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on-line gas phase chromatography technique, in the temperature range 350 - 600 C. Under the exact same chemical conditions, comparative studies with the lighter homologs of group-5 in the Periodic Table clearly indicate the volatility sequence being NbOCl
TaOCl
DbOCl
. From the obtained experimental results, thermochemical data for DbOCl
were derived. The present study delivers reliable experimental information for theoretical calculations on the chemical properties of transactinides.
Chiera, N. M.; Sato, Tetsuya; Tomitsuka, Tomohiro; Asai, Masato; Ito, Yuta; Shirai, Kaori*; Suzuki, Hayato; Tokoi, Katsuyuki; Toyoshima, Atsushi; Tsukada, Kazuaki; et al.
Journal of Radioanalytical and Nuclear Chemistry, 320(3), p.633 - 642, 2019/06
Times Cited Count:2 Percentile:18.62(Chemistry, Analytical)An isothermal gas-chromatographic (IGC) device has been developed and tested for on-line gas phase studies of volatile oxychlorides of short-lived group-5 transition metals. Radioisotopes of niobium and tantalum, produced in nuclear fusion evaporation reactions, are directly flushed into the IGC setup by an inert gas-jet. Oxychloride compounds are formed by the addition of SOCl and O
. Parameters influencing the formation and transport of NbOCl
and TaOCl
are investigated. For nuclides with half-lives (
) of about 30 s, an overall efficiency of 7% is obtained, rendering the IGC setup suitable for the chemical exploration of
Db(
= 34s).
Shirai, Hiroshi; Barabaschi, P.*; Kamada, Yutaka; JT-60SA Team
Fusion Engineering and Design, 109-111(Part B), p.1701 - 1708, 2016/11
Times Cited Count:22 Percentile:87.81(Nuclear Science & Technology)The JT-60SA Project has shown steady progress toward the first plasma in 2019. JT-60SA is a superconducting tokamak designed to operate in the break-even conditions for a long pulse duration with a maximum plasma current of 5.5 MA. Design and fabrication of JT-60SA components shared by EU and Japan started in 2007. Assembly in the torus hall started in January 2013, and welding work of the vacuum vessel sectors is currently on going on the cryostat base. Other components such as TF coils, PF coils, power supplies, cryogenic system, cryostat vessel, thermal shields and so forth were or are being delivered to Naka site for installation, assembly and commissioning. This paper gives technical progress on fabrication, installation and assembly of tokamak components and ancillary systems, as well as progress of JT-60SA Research Plan being developed jointly by EU and Japanese fusion communities.
Higashijima, Satoru; Kamada, Yutaka; Barabaschi, P.*; Shirai, Hiroshi; JT-60SA Team
Fusion Science and Technology, 68(2), p.259 - 266, 2015/09
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Yamada, Hidetaka; Yokoyama, Keiichi; Teranishi, Yoshiaki*; Sugita, Akihiro; Shirai, Toshizo*; Aoyama, Makoto; Akahane, Yutaka; Inoue, Norihiro*; Ueda, Hideki*; Yamakawa, Koichi; et al.
Physical Review A, 72(6), p.063404_1 - 063404_5, 2005/12
Times Cited Count:6 Percentile:30.96(Optics)A demonstration of coherent quantum control for ultrafast precise selection of closely-lying states is reported. A phase-locked pair of femtosecond laser pulses is generated through a pulse shaper to excite the ground-state cesium atom to the Cs(7) and Cs(7
) states by two-photon absorption. The excited state population is measured by detecting fluorescence from each spin-orbit state. By controlling the phase-difference of the pulse pair, an ultrafast precise selection is accomplished. The contrast ratio of the maximal to minimal selection ratio exceeds 10
with the delay less than 400 fs.
Neudatchin, S. V.*; Takizuka, Tomonori; Hayashi, Nobuhiko; Isayama, Akihiko; Shirai, Hiroshi; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Suzuki, Takahiro
Nuclear Fusion, 44(9), p.945 - 953, 2004/09
The formation of internal transport barriers (ITBs) near q=3 surfaces in normal shear (NrS) discharges of JT-60U is known. In reverse shear (RS) JT-60U plasmas, the role of q minimum (qmin) equal to 3.5,3,2.5,2 was not obvious for ITB formation. ITB-events (non-local confinement bifurcations inside and around ITB) are found in various NrS and RS plasmas. Under sufficient heating power, ITB-events are seen at rational and not rational values of qmin. The space-time evolution of Te and Ti is similar, suggesting the same mechanism of Te and Ti transport. The temporal formation of strong ITB under passing of qmin=3 (after periodical improvements and degradations via ITB-events) in RS mode is presented. Under smaller power, ITB-events are observed only at rational values of qmin. In a weak RS shot, abrupt rise of Te is seen at qmin=3.5, while more cases of Ti rise are observed. The difference of Te and Ti evolutions seen regularly under the low power, suggests decoupling of Te and Ti transport.
Neudatchin, S. V.*; Takizuka, Tomonori; Hayashi, Nobuhiko; Isayama, Akihiko; Shirai, Hiroshi; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Suzuki, Takahiro
Nuclear Fusion, 44(9), p.945 - 953, 2004/09
Times Cited Count:18 Percentile:50.51(Physics, Fluids & Plasmas)The formation of internal transport barriers (ITBs) near =2,3 surfaces in normal shear (NrS) discharges of JT-60U and JET is known. In reverse shear (RS) JT-60U plasmas, the role of
minimum (
) equal to 3.5,3,2.5,2 is not obvious for ITB formation. In this paper, the effect of low rational
values on ITB-events in JT-60U NrS and RS plasmas is investigated. Under sufficient neutral beam power (
8MW for 1.2-1.5MA/3.8T pulses), ITB-events are seen at rational and non-rational values of
. The space-time evolutions of
and
are similar, suggesting the same mechanism for
and
transports. The temporal formation of stronger ITB under passing
=3 (after periodical improvements and degradations via ITB-events) in RS H-mode with
=8MW is presented. Under smaller power, ITB-events are observed only at rational
values. In a weak RS shot with
=4MW, the abrupt rise of
is seen at
=3.5, while more cases of
rise are observed. The difference between the
and
evolutions for the low power suggests the decoupling of
and
transports.
Sakamoto, Yoshiteru; Suzuki, Takahiro; Ide, Shunsuke; Koide, Yoshihiko; Takenaga, Hidenobu; Kamada, Yutaka; Fujita, Takaaki; Fukuda, Takeshi; Takizuka, Tomonori; Shirai, Hiroshi; et al.
Nuclear Fusion, 44(8), p.876 - 882, 2004/08
Times Cited Count:35 Percentile:71.17(Physics, Fluids & Plasmas)Response of the ion thermal diffusivity to the radial electric field Er shear has been investigated in JT-60U and the following results were found. (1) In the case of positive magnetic shear (PS) plasma, the ion thermal diffusivity in the core region shows L mode state, weak internal transport barrier (ITB), and strong ITB depending upon the heating power. In the case of reversed magnetic shear (RS) plasma, however, no power degradation of the ion thermal diffusivity is observed. (2) In the case of weak ITB, the ion thermal diffusivity decreases gradually with increasing the Er shear for both PS and RS plasmas. There exists a threshold of an effective Er shear to change its state from weak to strong ITBs. (3) The threshold of the effective Er shear in the case of RS plasma is small compared with that in the case of PS plasma.
Yokoyama, Keiichi; Teranishi, Yoshiaki; Toya, Yukio; Shirai, Toshizo; Fukuda, Yuji; Aoyama, Makoto; Akahane, Yutaka; Inoue, Norihiro*; Ueda, Hideki; Yamakawa, Koichi; et al.
Journal of Chemical Physics, 120(20), p.9446 - 9449, 2004/05
Times Cited Count:6 Percentile:18.46(Chemistry, Physical)Optimal laser control for ultrafast selection of closely-lying excited states, whose energy separation is smaller than the laser bandwidth, is reported on the two-photon transition of atomic cesium; Cs(6S 7D
, J = 5/2 and 3/2). Selective excitation was carried out by pulse shaping of ultrashort laser pulses which were adaptively modulated in a closed-loop learning system handling eight parameters representing the electric field. Two-color fluorescence from the respective excited states was monitored to measure the selectivity. The fitness used in the learning algorithm was evaluated from the ratio of the fluorescence yield. After fifty generations, a pair of nearly transform-limitted pulses were obtained as an optimal pulse shape, proving the effectiveness of "Ramsey fringes" mechanism. The contrast of the selection ratio was improved by
30 % from the simple "Ramsey fringes" experiment.
Sakamoto, Yoshiteru; Shirai, Hiroshi; Fujita, Takaaki; Ide, Shunsuke; Takizuka, Tomonori; Oyama, Naoyuki; Kamada, Yutaka
Plasma Physics and Controlled Fusion, 46(5A), p.A299 - A304, 2004/05
Times Cited Count:70 Percentile:88.23(Physics, Fluids & Plasmas)no abstracts in English
Kurihara, Yuji; Yui, Mikazu; Tanai, Kenji; Kawakami, Susumu; Sugita, Yutaka; Taniguchi, Naoki; Hirai, Takashi
JNC TN8400 2004-006, 59 Pages, 2004/04
Following studies have been done in this papers in order to apply the technologies based on H12 report to the actual geological conditions of Horonobe underground research laboratory. 1.reconsidering the process of repository design, 2. arrangement of the relations between geological conditions and the performance of engineering barrier systems, 3.present the appropriate form of geological informations, 4.study on the stability of deposition hall.
Kurihara, Yuji; Yui, Mikazu; Tanai, Kenji; Kawakami, Susumu; Sugita, Yutaka; Taniguchi, Naoki; Hirai, Takashi
JNC TN8400 2004-002, 58 Pages, 2004/04
In this paper, the items of in-situ experiments at Horonobe URL with respect to the technical issues about reliability of long-term behavior of engineered barrier system were extracted. And the concepts of the experiments were studied from several points of view such as verification of models and getting the actual behavior. Extracted items of the in-situ experiments are as follows. Coupled Phenomena Test (THMC Test), Buffer & Rock Creep Test, Gas Migration Test, Over-pack Corrosion Test, High-pH Influence Test, Low Alkaline Concrete Execution Test, Engineering-Barrier Emplacement Test, Tunnel Plugging Test.
Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko; Nishinaka, Ichiro; Hirata, Masaru; Yaita, Tsuyoshi; Ichikawa, Shinichi; Nagame, Yuichiro; et al.
Journal of the American Chemical Society, 126(16), p.5219 - 5224, 2004/04
Times Cited Count:44 Percentile:72.61(Chemistry, Multidisciplinary)Fluoride complexation of element 104, rutherfordium (Rf), produced in the Cm(
O,5n)
Rf reaction has been studied by anion-exchange chromatography on an atom-at-a-time scale. The anion-exchangechromatographic behavior of Rf was investigated in 1.9-13.9 M hydrofluoric acid together with those of the group-4 elements Zr and Hf produced in the
O-induced reactions on Ge and Gd targets, respectively. It was found that the adsorption behavior of Rf on anion-exchange resin is quite different from those of Zr and Hf, suggesting the influence of relativistic effect on the fluoride complexation of Rf.
Neudatchin, S.*; Takizuka, Tomonori; Hayashi, Nobuhiko; Isayama, Akihiko; Shirai, Hiroshi; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Ito, Kimitaka*; Miura, Yukitoshi
Purazuma, Kaku Yugo Gakkai-Shi, 79(12), p.1218 - 1220, 2003/12
New type of edge-core instantaneous interplay in JT-60U high- plasmas is found. Abrupt in time and wide in space reduction of electron heat flux in the core (called ITB-event) is correlated in ms timescale with the start of an ELM. This result gives a hint of the control to form the ITB immedeately and non-locally by inducing the ELM-like MHD activity.
Takenaga, Hidenobu; Higashijima, Satoru; Oyama, Naoyuki; Bruskin, L. G.; Koide, Yoshihiko; Ide, Shunsuke; Shirai, Hiroshi; Sakamoto, Yoshiteru; Suzuki, Takahiro; Hill, K. W.*; et al.
Nuclear Fusion, 43(10), p.1235 - 1245, 2003/10
Times Cited Count:73 Percentile:88.50(Physics, Fluids & Plasmas)no abstracts in English
Mikkelsen, D. R.*; Shirai, Hiroshi; Urano, Hajime*; Takizuka, Tomonori; Kamada, Yutaka; Hatae, Takaki; Koide, Yoshihiko; Asakura, Nobuyuki; Fujita, Takaaki; Fukuda, Takeshi*; et al.
Nuclear Fusion, 43(1), p.30 - 39, 2003/01
Times Cited Count:29 Percentile:64.44(Physics, Fluids & Plasmas)The stiffness of thermal transport in ELMy H-modes is explained in a series of carefully chosen JT-60U plasmas, and measured temperature are compared with the predictions of several transport models. A heating power scan with constant Tped, a scan of pedestal temperature Tped with constant heating power, and an on/off-axis heating comparison are presented. Predictions of the RLWB and IFS/PPPL models generally agree with the measured temperature outside 0.3
, but the Multimode model uniformly predicts temperatures that are too high except in the central region.
Kamada, Yutaka; Fujita, Takaaki; Ishida, Shinichi; Kikuchi, Mitsuru; Ide, Shunsuke; Takizuka, Tomonori; Shirai, Hiroshi; Koide, Yoshihiko; Fukuda, Takeshi; Hosogane, Nobuyuki; et al.
Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.185 - 254, 2002/09
Times Cited Count:34 Percentile:45.45(Nuclear Science & Technology)With the main aim of providing physics basis for ITER and the steady-state tokamak reactors, JT-60/JT-60U has been developing and optimizing the operational concepts, and extending the discharge regimes toward sustainment of high integrated performance in the reactor relevant parameter regime. In addition to achievement of the equivalent break-even condition (QDTeq up to 1.25) and a high fusion triple product = 1.5E21 m-3skeV, JT-60U has demonstrated the integrated performance of high confinement, high beta-N, full non-inductive current drive with a large fraction of bootstrap current in the reversed magnetic shear and in the high-beta-p ELMy H mode plasmas characterized by both internal and edge transport barriers. The key factors in optimizing these plasmas are profile and shape controls. As represented by discovery of various Internal Transport Barriers, JT-60/JT-60U has been emphasizing freedom and restriction of profiles in various confinement modes. JT-60U has demonstrated applicability of these high confinement modes to ITER and also clarified remaining issues.
Sakamoto, Yoshiteru; Suzuki, Takahiro; Ide, Shunsuke; Koide, Yoshihiko; Takenaga, Hidenobu; Kamada, Yutaka; Fujita, Takaaki; Takizuka, Tomonori; Shirai, Hiroshi; Fukuda, Takeshi
Purazuma, Kaku Yugo Gakkai-Shi, 78(9), p.941 - 948, 2002/09
no abstracts in English