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Journal Articles

A Knowledge-sharing activity on the environmental radiation monitoring results affected by the Fukushima-Daiichi Nuclear Power Plant Accident at Tokai-Oarai area in Ibaraki Prefecture

Nakano, Masanao; Hosomi, Kenji; Nishimura, Shusaku; Matsubara, Natsumi; Okura, Takehisa; Kuramochi, Akihiko; Kawasaki, Masatsugu; Takeuchi, Erina; Fujii, Yutaka*; Jinno, Tsukasa*; et al.

Hoken Butsuri (Internet), 55(2), p.102 - 109, 2020/06

After the Fukushima-Daiichi Nuclear Power Station (1F) Accident in March 2011, the increase was significantly observed in a part of the result of the environmental radiation monitoring in Ibaraki prefecture. "The review meeting of the environmental effect from 1F accident" was established to discuss technically the fluctuation of monitoring data. The review meeting collected the monitoring data from the four nuclear operators, and discussed a fluctuating trend, $$^{134}$$Cs/$$^{137}$$Cs activity ratio, and so on. In this report, the results of the dose rate and $$^{137}$$Cs in fallout, surface soil, flatfish and seabed sediment are introduced. Also the problem solving in the review meeting is introduced.

Journal Articles

Intrinsic 2D ferromagnetism in V$$_{5}$$Se$$_{8}$$ epitaxial thin films

Nakano, Masaki*; Wang, Y.*; Yoshida, Satoshi*; Matsuoka, Hideki*; Majima, Yuki*; Ikeda, Keisuke*; Hirata, Yasuyuki*; Takeda, Yukiharu; Wadachi, Hiroki*; Kohama, Yoshimitsu*; et al.

Nano Letters, 19(12), p.8806 - 8810, 2019/12

 Times Cited Count:22 Percentile:91.07(Chemistry, Multidisciplinary)

Journal Articles

The Development of method for extinguishing / treating metallic sodium using calcium chloride

Abe, Yuta; Nagai, Keiichi; Maie, Mitsuyoshi*; Nakano, Natsuko*; Kawashima, Yuichi*; Takesue, Naohisa*; Saito, Junichi

Dai-23-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (USB Flash Drive), 5 Pages, 2018/06

no abstracts in English

Journal Articles

Characterization and storage of radioactive zeolite waste

Yamagishi, Isao; Nagaishi, Ryuji; Kato, Chiaki; Morita, Keisuke; Terada, Atsuhiko; Kamiji, Yu; Hino, Ryutaro; Sato, Hiroyuki; Nishihara, Kenji; Tsubata, Yasuhiro; et al.

Journal of Nuclear Science and Technology, 51(7-8), p.1044 - 1053, 2014/07

 Times Cited Count:9 Percentile:65.28(Nuclear Science & Technology)

For safe storage of zeolite wastes generated by treatment of radioactive saline water at the Fukushima Daiichi Nuclear Power Station, properties of the Herschelite adsorbent were studied and its adsorption vessel was evaluated for hydrogen production and corrosion. Hydrogen production depends on its water level and dissolved species because hydrogen is oxidized by radicals in water. It is possible to evaluate hydrogen production rate in Herschelite submerged in seawater or pure water by taking into account of the depth effect of the water. The reference vessel of decay heat 504 W with or without residual pure water was evaluated for the hydrogen concentration by thermal hydraulic analysis using obtained fundamental properties. Maximum hydrogen concentration was below the lower explosive limit (4 %). The steady-state corrosion potential of a stainless steel 316L increased with absorbed dose rate but its increase was repressed by the presence of Herschelite. At 750 Gy/h and $$<$$60$$^{circ}$$C which were values evaluated at the bottom of the vessel of 504 W, the localized corrosion of SUS316L contacted with Herschelite would not immediately occur under 20,000 ppm of Cl$$^{-}$$ concentration.

Journal Articles

Development of advanced inductive scenarios for ITER

Luce, T. C.*; Challis, C. D.*; Ide, Shunsuke; Joffrin, E.*; Kamada, Yutaka; Politzer, P. A.*; Schweinzer, J.*; Sips, A. C. C.*; Stober, J.*; Giruzzi, G.*; et al.

Nuclear Fusion, 54(1), p.013015_1 - 013015_15, 2013/12

 Times Cited Count:23 Percentile:80.5(Physics, Fluids & Plasmas)

Journal Articles

Hydrogen isotope effects on ITG scale length, pedestal and confinement in JT-60 H-mode plasmas

Urano, Hajime; Takizuka, Tomonori*; Aiba, Nobuyuki; Kikuchi, Mitsuru; Nakano, Tomohide; Fujita, Takaaki; Oyama, Naoyuki; Kamada, Yutaka; Hayashi, Nobuhiko; JT-60 Team

Nuclear Fusion, 53(8), p.083003_1 - 083003_8, 2013/08

 Times Cited Count:25 Percentile:80.03(Physics, Fluids & Plasmas)

Dependence of heat transport, edge pedestal and confinement on isotopic composition was investigated in conventional H-mode plasmas. Identical profiles for the electron density, electron temperature, and ion temperature were obtained for hydrogen and deuterium plasmas, whereas the required power clearly increased for hydrogen, which resulted in reduction of heat diffusivity for deuterium. The inverse of the ion-temperature-gradient (ITG) scale length which is required for a given ion heat diffusivity increased by a factor of approximately 1.2 for deuterium compared with that for hydrogen.

Journal Articles

Dependence of heat transport and confinement on isotopic composition in conventional H-mode plasmas in JT-60U

Urano, Hajime; Takizuka, Tomonori*; Kikuchi, Mitsuru; Nakano, Tomohide; Fujita, Takaaki; Oyama, Naoyuki; Kamada, Yutaka; Hayashi, Nobuhiko; JT-60 Team

Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/01

Dependence of heat transport on isotopic composition is investigated in conventional H-mode plasmas for the application to ITER. The identical profiles of $$n_mathrm{e}$$, $$T_mathrm{e}$$ and $$T_mathrm{i}$$ are obtained for hydrogen and deuterium plasmas while the required power becomes clearly larger for hydrogen, resulting in the reduction of the heat diffusivity for deuterium. The result of the identical temperature profiles in spite of different heating power suggests that the characteristics of heat conduction differs essentially between hydrogen and deuterium even at the same scale length of temperature gradient. On the other hand, the edge stability is improved by increased total $$beta_mathrm{p}$$ regardless of the difference of the isotropic composition.

Journal Articles

Energy confinement of hydrogen and deuterium H-mode plasmas in JT-60U

Urano, Hajime; Takizuka, Tomonori*; Fujita, Takaaki; Kamada, Yutaka; Nakano, Tomohide; Oyama, Naoyuki; JT-60 Team

Nuclear Fusion, 52(11), p.114021_1 - 114021_10, 2012/11

 Times Cited Count:16 Percentile:62.38(Physics, Fluids & Plasmas)

Energy confinement properties for hydrogen and deuterium H-mode plasmas are investigated. The stored energy for deuterium becomes larger approximately by a factor of 1.7-2.0 than that for hydrogen at a given heating power. When the stored energy is fixed for both cases, the required power differs roughly a factor of $$sim1.7$$ and the identical spatial profiles of electron density $$n_mathrm{e}$$, electron temperature $$T_mathrm{e}$$ and ion temperature $$T_mathrm{i}$$ are obtained. Despite almost the same power crossing the separatrix, type-I ELM frequency for hydrogen becomes approximately in double from that for deuterium. The pedestal pressure differs approximately by a factor of $$sim2$$ for the cases between hydrogen and deuterium plasmas at a given absorbed power. The relation between $$beta_mathrm{p}^mathrm{TOT}$$ and $$beta_mathrm{p}^mathrm{ped}$$ is almost identical regardless of the difference of the isotropic composition.

Journal Articles

Small ion-temperature-gradient scale length and reduced heat diffusivity at large hydrogen isotope mass in conventional $$H$$-mode plasmas

Urano, Hajime; Takizuka, Tomonori*; Kikuchi, Mitsuru; Nakano, Tomohide; Hayashi, Nobuhiko; Oyama, Naoyuki; Kamada, Yutaka

Physical Review Letters, 109(12), p.125001_1 - 125001_5, 2012/09

 Times Cited Count:21 Percentile:74.58(Physics, Multidisciplinary)

The dependence of the ion temperature gradient scale length on the hydrogen isotope mass was examined in conventional $$H$$-mode plasmas in JT-60U tokamak. While identical profiles for density and temperature were obtained for hydrogen and deuterium plasmas, the ion conductive heat flux necessary for hydrogen to sustain the same thermal stored energy was two times that required for deuterium, resulting in a clearly higher ion heat diffusivity for hydrogen at the same ion temperature gradient scale length. The ion temperature gradient scale length for deuterium is less than that for hydrogen at a given ion heat diffusivity.

Journal Articles

Highly sensitive detection of neodymium ion in small amount of spent nuclear fuel samples using novel fluorescent macrocyclic hexadentate polyaminocarboxylate probe in capillary electrophoresis-laser-induced fluorescence detection

Saito, Shingo*; Sato, Yoshiyuki*; Haraga, Tomoko; Nakano, Yuta*; Asai, Shiho; Kameo, Yutaka; Takahashi, Kuniaki; Shibukawa, Masami*

Journal of Chromatography A, 1232, p.152 - 157, 2012/04

 Times Cited Count:11 Percentile:41.46(Biochemical Research Methods)

A rapid and high-sensitive detection method of total concentration of Nd ion in a spent nuclear fuel sample is desirable since precise quantification of total Nd is useful as indicator of burnup. In this work, a capillary electrophoresis-laser-induced fluorescent detection method (CE-LIF) was proposed for analysis of total Nd in the spent fuel sample solution, employing a newly synthesized metal fluorescent probe with a fluorescein and a macrocylic hexadentate chelating group, FTC-ABNOTA, for lanthanide (Ln) ions. The mutual separation among the Ln-FTC-ABNOTA complexes was achieved by pH control providing dynamic ternary complexation with hydroxide ions. In this method, high resolution of Nd from other Ln ions with high resolution of 1.3-1.9 and a very low detection limit of 3.2 ppt were successfully obtained. A simulated spent fuel sample containing various metal ions was examined, so that a good quantification result with 99.3% recovery was obtained even with large excess of U.

Journal Articles

Energy confinement characterization of hydrogen and deuterium H-mode plasmas in JT-60U tokamak

Urano, Hajime; Takizuka, Tomonori*; Kikuchi, Mitsuru; Nakano, Tomohide; Fujita, Takaaki; Hayashi, Nobuhiko; Oyama, Naoyuki; Kamada, Yutaka; JT-60 Team

Europhysics Conference Abstracts (Internet), 36F, p.P1.016_1 - P1.016_4, 2012/00

Energy confinement properties for hydrogen and deuterium H-mode plasmas were examined in JT-60U. The energy confinement time became larger by a factor of $$sim$$1.2-1.3 for deuterium than for hydrogen at a given $$P_mathrm{L}$$. When the plasma energy was fixed, the profiles of density and temperature became identical for both cases while higher heating power was required for hydrogen. The ion conductive heat flux for hydrogen became approximately two times that for deuterium. Hence, the ion heat diffusivity for hydrogen was higher than for deuterium. It was found that the ion-temperature-gradient scale length became smaller by a factor of $$sim$$1.2 for deuterium than for hydrogen.

Journal Articles

Study of plasma current decay in the initial phase of high poloidal beta disruptions in JT-60U

Shibata, Yoshihide*; Watanabe, Kiyomasa*; Ono, Noriyasu*; Okamoto, Masaaki*; Isayama, Akihiko; Kurihara, Kenichi; Oyama, Naoyuki; Nakano, Tomohide; Kawano, Yasunori; Matsunaga, Go; et al.

Plasma and Fusion Research (Internet), 6, p.1302136_1 - 1302136_4, 2011/10

no abstracts in English

Journal Articles

Technical development for in-pile IASCC growth tests by using a 0.5T-CT specimen in JMTR

Chimi, Yasuhiro; Shibata, Akira; Ise, Hideo; Kasahara, Shigeki; Kawaguchi, Yoshihiko*; Nakano, Junichi; Omi, Masao; Nishiyama, Yutaka

Proceedings of Enlarged Halden Programme Group Meeting 2011 (CD-ROM), 10 Pages, 2011/10

In order to load a large specimen of 0.5T-CT up to a high stress intensity factor of $$sim$$30 MPa$$sqrt{m}$$, we have adopted a lever type loading unit for in-pile irradiation-assisted stress corrosion crack (IASCC) growth tests in the Japan Materials Testing Reactor (JMTR). In this unit, the applied load is generated by shrinking a bellows with lower inner gas pressure than surrounding water pressure and enlarged by leverage. The crack length of the specimen is monitored by potential drop method (PDM) using mineral insulator (MI) cables. In this paper, technical concerns of the in-pile crack growth test unit, especially the estimation procedure of applied load to the specimen inside the irradiation capsule and the evaluation of precision of the PDM signals are presented.

Journal Articles

Capillary electrophoresis with laser-induced fluorescent detection method using highly emissive probes for analysis of actinides in radioactive wastes

Haraga, Tomoko; Nakano, Yuta*; Shibukawa, Masami*; Kameo, Yutaka; Takahashi, Kuniaki; Saito, Shingo*

Proceedings of 14th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2011) (CD-ROM), p.1461 - 1465, 2011/09

Actinides are important nuclides for the analysis of radioactive wastes from nuclear fuel cycle facilities. In order to achieve simple and rapid analysis of actinides, capillary electrophoresis-laser-induced fluorescent detection method (CE-LIF) is one of the potential candidates. In this study, new emissive probes of actinide ions suitable for CE-LIF were developed for the first time. The detection and separation of americium and neptunium ions as model nuclides were examined using several new emissive complexing probes, each of which possessed a fluorophore and a different chelating moiety. Using acyclic and macrocyclic multidentate probes, the highly sensitive fluorescent detection of Am and Np was successfully achieved. The results suggests that the probe with an acyclic hexadentate chelating moiety is suitable for detection and separation of Am and Np. The detection limit of mid-ppt levels was determined.

Journal Articles

In-pile tests for IASCC growth behavior of irradiated 316L stainless steel under simulated BWR condition in JMTR

Chimi, Yasuhiro; Kasahara, Shigeki; Ise, Hideo; Kawaguchi, Yoshihiko*; Nakano, Junichi; Nishiyama, Yutaka

Proceedings of 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors (CD-ROM), p.1219 - 1228, 2011/08

The Japan Atomic Energy Agency (JAEA) has a plan of irradiation tests using the Japan Materials Testing Reactor (JMTR), in order to evaluate the effects of change in material properties and water chemistry caused by the neutron/$$gamma$$-ray irradiation on stress corrosion crack (SCC) growth of stainless steels from the view points of the integrity of reactor core internals for boiling water reactors (BWRs). The difference of SCC growth and its electrochemical corrosion potential (ECP) dependence between in-pile and out-of-pile tests is not fully understood because of a few in-pile data which is comparable with out-of-pile database. This paper presents a systematic review on SCC growth data of irradiated stainless steels and the outline of the in-pile test plan for crack growth of irradiated SUS316L stainless steel under simulated BWR conditions in the JMTR, together with the development of the in-pile test techniques.

Journal Articles

Plasma regimes and research goals of JT-60SA towards ITER and DEMO

Kamada, Yutaka; Barabaschi, P.*; Ishida, Shinichi; Ide, Shunsuke; Lackner, K.*; Fujita, Takaaki; Bolzonella, T.*; Suzuki, Takahiro; Matsunaga, Go; Yoshida, Maiko; et al.

Nuclear Fusion, 51(7), p.073011_1 - 073011_11, 2011/07

 Times Cited Count:55 Percentile:92.54(Physics, Fluids & Plasmas)

Journal Articles

Interactions between MHD instabilities in the wall-stabilized high-$$beta$$ plasmas

Matsunaga, Go; Aiba, Nobuyuki; Shinohara, Koji; Sakamoto, Yoshiteru; Takechi, Manabu; Suzuki, Takahiro; Asakura, Nobuyuki; Isayama, Akihiko; Oyama, Naoyuki; Yoshida, Maiko; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

Journal Articles

Study of current decay time during disruption in JT-60U tokamak

Shibata, Yoshihide*; Watanabe, Kiyomasa*; Okamoto, Masaaki*; Ono, Noriyasu*; Isayama, Akihiko; Kurihara, Kenichi; Nakano, Tomohide; Oyama, Naoyuki; Kawano, Yasunori; Matsunaga, Go; et al.

Nuclear Fusion, 50(2), p.025015_1 - 025015_7, 2010/01

 Times Cited Count:12 Percentile:46.71(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Long-pulse hybrid scenario development in JT-60U

Oyama, Naoyuki; Isayama, Akihiko; Matsunaga, Go; Suzuki, Takahiro; Takenaga, Hidenobu; Sakamoto, Yoshiteru; Nakano, Tomohide; Kamada, Yutaka; Ide, Shunsuke; JT-60 Team

Nuclear Fusion, 49(6), p.065026_1 - 065026_10, 2009/06

 Times Cited Count:30 Percentile:76.81(Physics, Fluids & Plasmas)

The performance and sustained duration of long-pulse discharges for ITER hybrid scenario have been improved in JT-60U. The peaked density profile in the core plasma can be maintained with NBIs for central heating even when the density at the pedestal increased in the latter phase of the discharge due to the increase in the divertor recycling. High normalized beta ($$beta_{rm N}$$) of 2.6 and high thermal confinement enhancement factor ($$H_{rm H98(y,2)} > 1$$) was sustained for 25 s ($${sim}14 tau_{rm R}$$, where $$tau_{rm R}$$ is the current diffusion time.) under the ITER relevant small toroidal rotation condition. High $$beta_{rm N}H_{rm H98(y,2)}$$ of 2.6 gives high G-factor ($$beta_{rm N}H_{rm H98(y,2)}/q_{rm 95}^{2}$$) of 0.25 and peaked pressure profile gives large bootstrap current fraction ($$f_{rm BS} > 0.43$$).

Journal Articles

Report of meetings of ITPA (International Tokamak Physics Activity), 19

Sasao, Mamiko*; Kusama, Yoshinori; Kawano, Yasunori; Kawahata, Kazuo*; Mase, Atsushi*; Sugie, Tatsuo; Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 83(9), p.779 - 782, 2007/09

This is a report of highlights from 2007 spring meetings of seven Topical Groups (TG) of International Tokamak Physics Activity (ITPA). In each meeting, high priority issues in physics of International Thermonuclear Experimental Reactor (ITER) and other burning plasma experiments have been discussed and investigated. Twenty-seven scientists from Japan have participated in those meetings. Dates and places of the meetings are shown below. (1) Diagnostics TG: 26-30 March, Princeton (USA), (2) Transport Physics TG: 7-10 May, Lausanne (Switzerland), (3) Confinement Database and Modeling TG: 7-10 May, Lausanne (Switzerland), (4) Edge Pedestal Physics TG: 7-10 May, Garching (Germany) (5) Steady State Operation TG: 9-11 May, Daejeon (South Korea), (6)MHD TG: 21-24 May, San Diego (USA), (7) Scrape-off-layer and Divertor Physics TG: 7-10 May, Garching (Germany).

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