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Journal Articles

Continuous extraction and separation of Am(III) and Cm(III) using a highly practical diamide amine extractant

Suzuki, Hideya; Tsubata, Yasuhiro; Kurosawa, Tatsuya*; Sagawa, Hiroshi*; Matsumura, Tatsuro

Journal of Nuclear Science and Technology, 54(11), p.1163 - 1167, 2017/11

 Times Cited Count:12 Percentile:9(Nuclear Science & Technology)

A highly practical diamide-type extractant, which is an alkyl diamide amine with 2-ethylhexyl alkyl chains (ADAAM(EH)), was investigated for mutual separation of Am(III) and Cm(III). ADAAM(EH) is a multidentate ligand with one soft N-donor atom and two hard O-donor atoms in its central frame. This tridentate arrangement of donor atoms provides selective binding to Am(III) compared to that with Cm(III) in highly acidic media, resulting in separation factors of up to 5.5. A continuous liquid-liquid extraction and stripping test was conducted using a multistage countercurrent mixer-settler extractor with ADAAM(EH) in n-dodecane. In this test, separation of Am(III) and Cm(III) was achieved with very high yield.

Journal Articles

Determination of reactivity and neutron flux using modified neural network for HTGR

Subekti, M.*; Kudo, Kazuhiko*; Nabeshima, Kunihiko; Takamatsu, Kuniyoshi

Atom Indonesia, 43(2), p.93 - 102, 2017/08

Reactor kinetics based on point kinetic model have been generally applied as the standard method for neutronics codes. As the central control rod (C-CR) withdrawal test has demonstrated in a prismatic core of HTTR, the transient calculation of kinetic parameter, such as reactivity and neutron fluxes, requires a new method to shorten calculation-process time. Development of neural network method was applied to point kinetic model as the necessity of real-time calculation that could work in parallel with the digital reactivity meter. The combination of TDNN and Jordan RNN, such as TD-Jordan RNN, was the result of the modeling approach. The application of TD-Jordan RNN with adequate learning, tested offline, determined results accurately even when signal inputs were noisy. Furthermore, the preprocessing for neural network input utilized noise reduction as one of the equations to transform two of twelve time-delayed inputs into power corrected inputs.

JAEA Reports

Determination of metal impurities in MOX powder by direct current arc atomic emission spectroscopy; Application of standard addition method for direct analysis of powder sample

Furuse, Takahiro*; Taguchi, Shigeo; Kuno, Takehiko; Surugaya, Naoki

JAEA-Technology 2016-028, 19 Pages, 2016/12


Metal impurities in MOX powder obtained from uranium and plutonium recovered from reprocessing process of spent nuclear fuel are needed to be determined for its characterization. Direct current arc atomic emission spectroscopy (DCA-AES) is one of the useful methods for direct analysis of powder sample without dissolving the analyte into aqueous solution. However, the selection of standard material, which can overcome concerns such as matrix matching, is quite important to create adequate calibration curves for DCA-AES. In this study, we apply standard addition method using the certified U$$_{3}$$O$$_{8}$$ containing known amounts of metal impurities to avoid the matrix problems. The proposed method provides good results for determination of Fe, Cr and Ni at a significant quantity level contained in MOX samples.

Journal Articles

Study on magnetic property change on neutron irradiated austenitic stainless steel

Nemoto, Yoshiyuki; Oishi, Makoto; Ito, Masayasu; Kaji, Yoshiyuki

Nippon Hozen Gakkai Dai-12-Kai Gakujutsu Koenkai Yoshishu, p.105 - 112, 2015/07

Authors previously reported that Eddy current method and AC magnetization method have potential to be applied for development of diagnostic technics to detect the sign of material degradation before cracking on the austenitic stainless steels used as structural material in nuclear power plants. In typical austenitic stainless steels such as type304, magnetic ferrite phase would exist in the alloy before irradiation, and it is concerned to disturb the magnetic measurement on irradiated material. Magnetic measurements were conducted in this work on type304 austenitic stainless steel specimens irradiated up to different doses. In addition, microstructure observation was conducted on the area including grain boundary to discuss the correlation of magnetization on irradiated austenitic stainless alloy and grain boundary cracking. Obtained magnetic data on irradiated type304 stainless steel were seen clearly different from that on un-irradiated specimen, and showed positive correlation with radiation dose, therefore it was thought that magnetic measurement technics can be applied for the material which contains certain quantity of ferrite phase before irradiation. In the microstructural observation, magnetic phase (FeNi$$_{3}$$) formation along the grain boundary was revealed.

Journal Articles

Spinmotive force due to motion of magnetic bubble arrays driven by magnetic field gradient

Yamane, Yuta*; Hemmatiyan, S.*; Ieda, Junichi; Maekawa, Sadamichi; Sinova, J.*

Scientific Reports (Internet), 4, p.6901_1 - 6901_5, 2014/11

 Times Cited Count:12 Percentile:43.83(Multidisciplinary Sciences)

Interaction between local magnetization and conduction electrons is responsible for a variety of phenomena in magnetic materials. It has been recently shown that spin current and associated electric voltage can be induced by magnetization that depends on both time and space. This effect, called spinmotive force, provides for a powerful tool for exploring the dynamics and the nature of magnetic textures, as well as a new source for electromotive force. Here we theoretically demonstrate the generation of electric voltages in magnetic bubble array systems subjected to a magnetic field gradient. It is shown by deriving expressions for the electric voltages that the present system offers a direct measure of phenomenological parameter $$beta$$ that describes non-adiabaticity in the current induced magnetization dynamics. This spinmotive force opens a door for new types of spintronic devices that exploit the field-gradient.

Journal Articles

Roles of the double tearing mode on the formation of a current hole

Tsuda, Takashi; Kurita, Genichi; Fujita, Takaaki

Journal of Plasma Physics, 72(6), p.1149 - 1152, 2006/12

 Times Cited Count:3 Percentile:87.96(Physics, Fluids & Plasmas)

The current density is expected to be negative in the central region of the tokamak when the amplitude of bootstrap current or off-axis current drive is large enough and a negative one-turn voltage exists. However, a flat current profile with almost zero value has been observed in experiments. The current profile with Current Hole has a tendency to be unstable to double tearing mode and we investigate the role of double tearing mode on the formation of Current Hole with RMHD simulation.

Journal Articles

Stability of double tearing mode in current hole configuration

Tsuda, Takashi; Kurita, Genichi; Fujita, Takaaki

Journal of the Korean Physical Society, 49, p.S83 - S86, 2006/12

The current density is expected to be negative in the central region of the tokamak when the amplitude of bootstrap current or off-axis current drive is large enough. However, a flat current profile with almost zero value has been observed in experiments even under the situation with negative one-turn voltage exists in the central region of plasma. Double tearing mode (DTM) can be unstable for the current profile with a "current hole" and some MHD activities are observed in JET before the formation of the current hole. On the contrary, no MHD activity is observed in the JT-60 experiment. Here, we study the condition of appearance of DTM and investigate the stability of DTM and the interaction between DTM (n=1 perturbation) and "Current Hole" with resistive RMHD simulations.

Journal Articles

A New model to simulate critical current degradation of a large CICC by taking into account strand bending

Koizumi, Norikiyo; Nunoya, Yoshihiko; Okuno, Kiyoshi

IEEE Transactions on Applied Superconductivity, 16(2), p.831 - 834, 2006/06

 Times Cited Count:24 Percentile:26.83(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Numerical simulation of the critical current and n-value in Nb$$_{3}$$Sn strand subjected to bending strain

Hirohashi, Masayuki*; Murakami, Haruyuki*; Ishiyama, Atsushi*; Ueda, Hiroshi*; Koizumi, Norikiyo; Okuno, Kiyoshi

IEEE Transactions on Applied Superconductivity, 16(2), p.1721 - 1724, 2006/06

 Times Cited Count:9 Percentile:51.19(Engineering, Electrical & Electronic)

To demonstrate the applicability of Nb$$_{3}$$Sn CICCs to ITER, four Nb$$_{3}$$Sn model coils have been constructed and tested. The experimental results showed that the measured critical current (Ic) degraded. In addition, the larger is the applied electromagnetic force, the larger the magnitude of the degradation is. The degradation in n-value was also observed. One of the explanations of this degradation is a local strand bending. This consideration has been supported by the test results. However, general dependence of Ic on periodic bending strain has not been clarified in this test since the experiments were carried out at a certain magnetic field, temperature and strain. Therefore, a numerical simulation code was developed to study the general dependence of the Ic and n-value of the Nb$$_{3}$$Sn strand on periodic bending strain. A distributed constant circuit model is applied to simulate current transfer among the filaments in the strand. The simulation results show relatively good agreement with the experiment results but some modification in modeling is required for more accurate simulation.

Journal Articles

Evaluation of the 3-Gev proton beam profile at the spallation target of the JSNS

Meigo, Shinichiro; Noda, Fumiaki*; Ishikura, Shuichi*; Futakawa, Masatoshi; Sakamoto, Shinichi; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research A, 562(2), p.569 - 572, 2006/06

 Times Cited Count:13 Percentile:30.32(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Acceleration of MeV-class energy, high-current-density H$$^{-}$$-ion beams for ITER neutral beam system

Taniguchi, Masaki; Inoue, Takashi; Kashiwagi, Mieko; Watanabe, Kazuhiro; Hanada, Masaya; Seki, Takayoshi*; Dairaku, Masayuki; Sakamoto, Keishi

Review of Scientific Instruments, 77(3), p.03A514_1 - 03A514_4, 2006/03

 Times Cited Count:13 Percentile:42.26(Instruments & Instrumentation)

In the ITER NB systems, conventional gas insulation technology cannot be utilized because of the conductivity of the insulation gas caused by the radiation from the tokamak plasma. To overcome this problem, a vacuum insulated beam source (VIBS), where the whole beam source is immersed in vacuum, has been developed in JAERI. Recently, voltage holding capability of the VIBS was drastically improved by installing the large stress ring and these progress enables us to perform the high power operation of the VIBS accelerator. For high current density H$$^{-}$$- beam acceleration, modifications were made on KAMABOKO source. At present, H$$^{-}$$- beam current density is 146 A/m$$^{2}$$ at 836 keV (input arc power; 40 kW, operation pressure; 0.3 Pa).The acceleration of 900 keV, 0.1 A level beam was accomplished for 175 shots during the test campaign. The beam acceleration was quite stable and the degradation of the voltage holding due to the beam acceleration and/or Cs seeding was not observed.

Journal Articles

Design study of superconducting coils for the fusion DEMO plant at JAERI

Isono, Takaaki; Koizumi, Norikiyo; Okuno, Kiyoshi; Kurihara, Ryoichi; Nishio, Satoshi; Tobita, Kenji

Fusion Engineering and Design, 81(8-14), p.1257 - 1261, 2006/02

 Times Cited Count:4 Percentile:66.66(Nuclear Science & Technology)

In order to realize an economically competitive power generation system, generation of a higher field is required. Toroidal Field (TF) coils of fusion DEMO plant at JAERI are required to generate magnetic field of 16 to 20 T. To realize this high field, advanced superconducting materials, such as Nb$$_3$$Al and high temperature superconductor (HTS), are considered. HTS has enough performance in a 20-T field at 4 K, and a forced-cooled type HTS conductor using a silver alloy sheathed Bi-2212 round wire has been proposed. Required areas of superconductor, structure, stabilizer, coolant and insulator in the cross section of coil winding have been calculated. However, there are many technical issues to be solved, such as accurate temperature control during heat treatment in an atmosphere of oxygen. On the other hand, a large coil using Nb$$_3$$Al has been developed by JAERI, and major technology to fabricate a 16-T Nb$$_3$$Al coil was developed. Validity and issues of grading the winding area are discussed, and there is a possibility to increase a field up to around 17 T using the method.

Journal Articles

Heating, current drive, and advanced plasma control in JFT-2M

Hoshino, Katsumichi; Yamamoto, Takumi; Tamai, Hiroshi; Oasa, Kazumi; Kawashima, Hisato; Miura, Yukitoshi; Ogawa, Toshihide; Shoji, Teruaki*; Shibata, Takatoshi; Kikuchi, Kazuo; et al.

Fusion Science and Technology, 49(2), p.139 - 167, 2006/02

 Times Cited Count:2 Percentile:81.41(Nuclear Science & Technology)

The main results obtained by the various heating and current drive systems, external coil system and divertor bias system are reviewed from the viewpoint of the advanced active control of the tokamak plasma. Also, the features of each system are described. The contribution of the JFT-2M in these areas are summarized.

Journal Articles

Development of beam generation and irradiation technology for electrostatic accelerators

Chiba, Atsuya; Uno, Sadanori; Okoshi, Kiyonori; Yamada, Keisuke; Saito, Yuichi; Ishii, Yasuyuki; Sakai, Takuro; Sato, Takahiro; Mizuhashi, Kiyoshi

JAEA-Review 2005-001, TIARA Annual Report 2004, p.358 - 360, 2006/01

no abstracts in English

Journal Articles

Design study of national centralized tokamak facility for the demonstration of steady state high-$$beta$$ plasma operation

Tamai, Hiroshi; Akiba, Masato; Azechi, Hiroshi*; Fujita, Takaaki; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; Hosogane, Nobuyuki; Ichimura, Makoto*; et al.

Nuclear Fusion, 45(12), p.1676 - 1683, 2005/12

 Times Cited Count:15 Percentile:51.03(Physics, Fluids & Plasmas)

Design studies are shown on the National Centralized Tokamak facility. The machine design is carried out to investigate the capability for the flexibility in aspect ratio and shape controllability for the demonstration of the high-beta steady state operation with nation-wide collaboration, in parallel with ITER towards DEMO. Two designs are proposed and assessed with respect to the physics requirements such as confinement, stability, current drive, divertor, and energetic particle confinement. The operation range in the aspect ratio and the plasma shape is widely enhanced in consistent with the sufficient divertor pumping. Evaluations of the plasma performance towards the determination of machine design are presented.

Journal Articles

Analysis of the direction of plasma vertical movement during major disruptions in ITER

Lukash, V.*; Sugihara, Masayoshi; Gribov, Y.*; Fujieda, Hirobumi*

Plasma Physics and Controlled Fusion, 47(12), p.2077 - 2086, 2005/12

 Times Cited Count:6 Percentile:77(Physics, Fluids & Plasmas)

Vertical directions of plasma movement after the thermal quench (TQ) of major disruptions in ITER are investigated using the predictive mode of the DINA code. Three dominant parameters in determining the direction of plasma movement are identified; (1) the rate of plasma current quench, (2) change of the internal plasma inductance li associated with the TQ and (3) the initial vertical position of plasma column before the TQ. It is shown that the reference ITER plasma moves upward after the TQ, if the current quench rate is higher than 200kA/ms and the drop of li does not exceed 0.2 for the present reference initial vertical position (55.5 cm above the center of machine).

Journal Articles

Performance of the LH antenna with carbon grill in JT-60U

Seki, Masami; Moriyama, Shinichi; Shinozaki, Shinichi; Hasegawa, Koichi; Hiranai, Shinichi; Yokokura, Kenji; Shimono, Mitsugu; Terakado, Masayuki; Fujii, Tsuneyuki

Fusion Engineering and Design, 74(1-4), p.273 - 277, 2005/11

 Times Cited Count:3 Percentile:73.72(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Updating the design of the feeder components for the ITER magnet system

Yoshida, Kiyoshi; Takahashi, Yoshikazu; Isono, Takaaki; Mitchell, N.*

Fusion Engineering and Design, 75-79, p.241 - 247, 2005/11

 Times Cited Count:10 Percentile:40.01(Nuclear Science & Technology)

The ITER superconducting magnet system stores energy of 50 GJ during plasma operation, and generates an average heat load of 23 kW at 4 K to cryoplant. The helium is distributed to the coil through 30 separate feeder lines. The feeders also contain the electrical supplies to the coil and are integrated into the current lead transition to room temperature. The interface components between the coils and the service facilities (power supply and cryogenic plant) consist of the in-cryostat feeders, the cryostat feedthroughs, and the coil terminal boxes (CTBs). The cryostat feedthroughs with S-bend boxes allow thermal contraction of the magnet system. The layout of the in-cryostat feeders takes into consideration routing restrictions in the cryostat and initial assembly with other Tokamak components. The forced-flow-cooled current leads with a conventional copper heat exchanger in the CTBs are adapted to fit in the limited space in the building. This paper presents the latest design concept and parameters of the feeder components.

Journal Articles

Overview of JT-60U progress towards steady-state advanced tokamak

Ide, Shunsuke; JT-60 Team

Nuclear Fusion, 45(10), p.S48 - S62, 2005/10

 Times Cited Count:50 Percentile:14.88(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Enhanced electrochemical oxidation of spent organic solvent under ultrasonic agitation

Sugikawa, Susumu; Umeda, Miki; Kobayashi, Fuyumi; Nagata, Masanobu*; Dojiri, Shigeru; Amano, Masae*

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 4 Pages, 2005/10

The mineralization of radioactive contaminated organic wastes by mediated electrochemical oxidation process has some attractive features as alternative to incineration process: The process operates safely at low temperatures and ambient pressures. JAERI has been investigated the process since 1996 and confirmed complete mineralization of this organic solvent. In order to greatly improve current efficiency for the oxidation reaction, further experiments were performed under condition of strong mixing of organic solvent and anolyte with an aide of ultrasonic wave. The current efficiencies for the oxidation reaction by ultrasonic agitation between organic solvent and anolyte were twice to that by mechanical agitation. On the basis of these results, two processes, one for destruction of a small amount of TBP/dodecane and the other for destruction of intermediate compounds following alkaline hydrolysis of a large amount of TBP/dodecane, were proposed.

298 (Records 1-20 displayed on this page)