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Journal Articles

Neutron capture cross section and capture $$gamma$$-ray spectrum of $$^{88}$$Sr in the stellar nucleosynthesis energy region

Katabuchi, Tatsuya*; Igashira, Masayuki*; Kamada, So*; Tajika, Michihide*; Iwamoto, Nobuyuki; Kawano, Toshihiko*

Physical Review C, 108(3), p.034610_1 - 034610_12, 2023/09

Journal Articles

Detection of Simulated Fukushima Daiichi Fuel Debris Using a Remotely Operated Vehicle at the Naraha Test Facility

Nancekievill, M.*; Espinosa, J.*; Watson, S.*; Lennox, B.*; Jones, A.*; Joyce, M. J.*; Katakura, Junichi*; Okumura, Keisuke; Kamada, So*; Kato, Michio*; et al.

Sensors (Internet), 19(20), p.4602_1 - 4602_16, 2019/10

 Times Cited Count:6 Percentile:39.03(Chemistry, Analytical)

In order to contribute to fuel debris search at the Fukushima Daiichi Nuclear Power Station, we developed a system to search for submerged fuel debris by mounting a sonar on the remotely operated vehicle (ROV). The system can obtain 3D images of submerged fuel debris in real time by using the positioning system, depth sensor, and collected sonar data. As a demonstration test, a simulated fuel debris was installed at the bottom of the water tank facility at the Naraha Center for Remote Control Technology Development, and a 3D image was successfully obtained.

Journal Articles

A Method for the prediction of the dose rate distribution in a primary containment vessel of the Fukushima Daiichi Nuclear Power Station

Okumura, Keisuke; Riyana, E. S.; Sato, Wakaei*; Maeda, Hirobumi*; Katakura, Junichi*; Kamada, So*; Joyce, M. J.*; Lennox, B.*

Progress in Nuclear Science and Technology (Internet), 6, p.108 - 112, 2019/01

In order to establish the prediction method of the dose rate distribution in the primary containment vessel (PCV) of the Fukushima Daiichi Nuclear Power Station, a series of calculations were carried out in the following way; (1) burnup calculation to obtain fuel composition at the time of accident, (2) activation calculation for the structural materials including impurities, (3) estimation of Cs contamination in PCV based on the result of severe accident analysis by IRID, (4) decay calculation of radioactive nuclides, (5) photon transport calculation to obtain dose rate distribution. After that, Cs concentration around the dry-well of 1F was modified to be consistent with locally measured dose rates in the PCV-investigation by IRID.

Journal Articles

Development of ROV system to explore fuel debris in the Fukushima Daiichi Nuclear Power Plant

Kamada, So*; Kato, Michio*; Nishimura, Kazuya*; Nancekievill, M.*; Watson, S.*; Lennox, B.*; Jones, A.*; Joyce, M. J.*; Okumura, Keisuke; Katakura, Junichi*

Progress in Nuclear Science and Technology (Internet), 6, p.199 - 202, 2019/01

As a technology development to investigate the distribution of submerged fuel debris in the primary containment vessel (PCV) of the Fukushima Daiichi Nuclear Power Station, we are conducting development experiments of sonar system to be mounted in a compact ROV. The experiments were conducted in two types of water tanks with different depths, simulating the PCV, using sonar with different sizes, ultrasonic frequencies, and beam scanning method, and simulated fuel debris. As a result, we characterized the shape discrimination performance of the simulated debris, and the noise due to multi-path in narrow closed space.

Journal Articles

Development of a radiological characterization submersible ROV for use at Fukushima Daiichi

Nancekievill, M.*; Jones, A. R.*; Joyce, M. J.*; Lennox, B.*; Watson, S.*; Katakura, Junichi*; Okumura, Keisuke; Kamada, So*; Kato, Michio*; Nishimura, Kazuya*

IEEE Transactions on Nuclear Science, 65(9), p.2565 - 2572, 2018/09

 Times Cited Count:19 Percentile:91.25(Engineering, Electrical & Electronic)

In order to contribute to the development of technology to search fuel debris submerged in water inside the primary containment vessel of the Fukushima Daiichi Nuclear Power Station, we are developing a remotely operated vehicle (ROV) system equipped with a compact radiation detector and sonar. A cerium bromide (CeBr$$_{3}$$) scintillator detector for dose rate monitoring and $$gamma$$ ray spectroscopy was integrated into ROV and experimentally validated with a $$^{137}$$Cs source, both in the conditions of laboratory and submerged. In addition, the ROV combined with the IMAGENEX 831L sonar could characterize the shape and size of a simulated fuel debris at the bottom of the water pool facility.

Journal Articles

A Remote-operated system to map radiation dose in the Fukushima Daiichi primary containment vessel

Nancekievill, M.*; Jones, A. R.*; Joyce, M. J.*; Lennox, B.*; Watson, S.*; Katakura, Junichi*; Okumura, Keisuke; Kamada, So*; Kato, Michio*; Nishimura, Kazuya*

Proceedings of 5th International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications (ANIMMA 2017) (USB Flash Drive), 6 Pages, 2017/06

We are developping a submersible ROV system, coupled with radiation detectors aimed at mapping the interior of the reactors at the Fukushima Daiichi Nuclear Power Station. To map the $$gamma$$-ray intensity environment a cerium bromide (CeBr$$_{3}$$) inorganic scintillator detector sensitive to $$gamma$$-rays has been incorporated into the ROV to measure $$gamma$$-ray intensity and identify radioactive isotopes. The ROV is a cylindrical shape with a diameter of about 150 mm, and it have two end caps of five pumps each allowing control of the ROV in 5 degree of freedom. It is possible to directly replace the CeBr$$_{3}$$ detector with a single crystal chemical vapour deposition (CVD) neutron detector with a $$^{6}$$Li convertor foil that is capable of mapping the thermal neutron flux.

Journal Articles

Measurements of neutron capture cross section for $$^{207,208}$$Pb

Segawa, Mariko; Toh, Yosuke; Harada, Hideo; Kitatani, Fumito; Koizumi, Mitsuo; Fukahori, Tokio; Oshima, Masumi*; Iwamoto, Nobuyuki; Iwamoto, Osamu; Hatsukawa, Yuichi; et al.

AIP Conference Proceedings 1594, p.339 - 344, 2014/05

 Times Cited Count:0 Percentile:0.02

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:29 Percentile:83.75(Physics, Fluids & Plasmas)

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

JENDL-4.0; A New library for nuclear science and engineering

Shibata, Keiichi; Iwamoto, Osamu; Nakagawa, Tsuneo*; Iwamoto, Nobuyuki; Ichihara, Akira; Kunieda, Satoshi; Chiba, Satoshi; Furutaka, Kazuyoshi; Otsuka, Naohiko*; Osawa, Takaaki*; et al.

Journal of Nuclear Science and Technology, 48(1), p.1 - 30, 2011/01

 Times Cited Count:1511 Percentile:100(Nuclear Science & Technology)

The fourth version of Japanese Evaluated Nuclear Data Library has been produced. In the new library, much emphasis is placed on the improvements of fission product and minor actinoid data. Two nuclear model codes were developed to evaluate the cross sections of fission products and minor actinoids. Coupled-channel optical model parameters, which can be applied to wide mass and energy regions, were obtained for nuclear model calculations. Thermal cross sections of actinoids were determined by considering recent experimental data or by the systematics of neighboring nuclei. A simultaneous evaluation was performed for the fission cross sections of important uranium and plutonium isotopes above 10 keV. The data on FP were re-evaluated, and new evaluations were performed for 30 nuclides. The data on light elements and structural materials were partly re-evaluated. The new library was released as JENDL-4.0 in May 2010.

Journal Articles

Calculation of neutron nuclear data on selenium isotopes for JENDL-4

Kamada, So*; Shibata, Keiichi; Ichihara, Akira; Kunieda, Satoshi

Journal of Nuclear Science and Technology, 47(4), p.329 - 339, 2010/04

 Times Cited Count:9 Percentile:53.03(Nuclear Science & Technology)

Neutron nuclear data on $$^{74, 76, 77, 78, 79, 80, 82}Se$$ have been calculated for the evaluated nuclear data library JENDL-4. Simultaneously calculated are the total, elastic and inelastic scattering, (n,p), (n,d), (n,t), (n,$$rm{^{3}He}$$), (n,$$alpha$$), (n,np), (n,nd), (n,n$$alpha$$), (n,2n), (n,3n) reaction cross sections, the angular distributions of emitted particles, and the energy distributions of emitted particles and $$gamma$$-rays. The statistical model was applied to calculate these quantities. Coupled-channel optical model parameters were used for neutrons. Preequilibrium and direct-reaction processes were taken into account in addition to the compound process. The present calculations are consistent with available experimental data. The calculated results are compiled into JENDL-4.

Journal Articles

Pedestal stability comparison and ITER pedestal prediction

Snyder, P. B.*; Aiba, Nobuyuki; Beurskens, M.*; Groebner, R. J.*; Horton, L. D.*; Hubbard, A. E.*; Hughes, J. W.*; Huysmans, G. T. A.*; Kamada, Yutaka; Kirk, A.*; et al.

Nuclear Fusion, 49(8), p.085035_1 - 085035_8, 2009/08

 Times Cited Count:167 Percentile:98.68(Physics, Fluids & Plasmas)

The pressure at the top of the edge transport barrier impacts fusion performance, while large ELMs can constrain material lifetimes. Investigation of intermediate wavelength MHD mode has led to improved understanding of the pedestal height and the mechanism for ELMs. The combination of high resolution diagnostics and a suite of stability codes has made edge stability analysis routine, and contribute both to understanding, and to experimental planning and performance optimization. Here we present extensive comparisons of observations to predicted edge stability boundaries on several tokamaks, both for the standard (Type I) ELM regime, and for small ELM and ELM-free regimes. We further discuss a new predictive model for the pedestal height and width (EPED1), developed by self-consistently combining a simple width model with peeling-ballooning stability calculations. This model is tested against experimental measurements, and used in initial predictions of the pedestal height for ITER.

Journal Articles

Experimental studies of ITER demonstration discharges

Sips, A. C. C.*; Casper, T.*; Doyle, E. J.*; Giruzzi, G.*; Gribov, Y.*; Hobirk, J.*; Hogeweij, G. M. D.*; Horton, L. D.*; Hubbard, A. E.*; Hutchinson, I.*; et al.

Nuclear Fusion, 49(8), p.085015_1 - 085015_11, 2009/08

 Times Cited Count:52 Percentile:87.07(Physics, Fluids & Plasmas)

Key parts of the ITER scenarios are determined by the capability of the proposed poloidal field (PF) coil set. They include the plasma breakdown at low loop voltage, the current rise phase, the performance during the flat top (FT) phase and a ramp down of the plasma. The ITER discharge evolution has been verified in dedicated experiments. New data are obtained from C-Mod, ASDEX Upgrade, DIII-D, JT-60U and JET. Results show that breakdown for $$E$$$$_{axis}$$ $$<$$ 0.23-0.33 V m$$^{-1}$$ is possible unassisted (ohmic) for large devices like JET and attainable in devices with a capability of using ECRH assist. For the current ramp up, good control of the plasma inductance is obtained using a full bore plasma shape with early X-point formation. This allows optimization of the flux usage from the PF set. Additional heating keeps $$l$$$$_{i}$$(3) $$<$$ 0.85 during the ramp up to $$q$$$$_{95}$$ = 3. A rise phase with an H-mode transition is capable of achieving $$l$$$$_{i}$$(3) $$<$$ 0.7 at the start of the FT. Operation of the H-mode reference scenario at $$q$$$$_{95}$$ $$sim$$ 3 and the hybrid scenario at $$q$$$$_{95}$$ = 4-4.5 during the FT phase is documented, providing data for the $$l$$$$_{i}$$(3) evolution after the H-mode transition and the $$l$$$$_{i}$$(3) evolution after a back-transition to L-mode. During the ITER ramp down it is important to remain diverted and to reduce the elongation. The inductance could be kept $$leq$$ 1.2 during the first half of the current decay, using a slow $$I$$$$_{p}$$ ramp down, but still consuming flux from the transformer. Alternatively, the discharges can be kept in H-mode during most of the ramp down, requiring significant amounts of additional heating.

Journal Articles

Neoclassical tearing mode control using electron cyclotron current drive and magnetic island evolution in JT-60U

Isayama, Akihiko; Matsunaga, Go; Kobayashi, Takayuki; Moriyama, Shinichi; Oyama, Naoyuki; Sakamoto, Yoshiteru; Suzuki, Takahiro; Urano, Hajime; Hayashi, Nobuhiko; Kamada, Yutaka; et al.

Nuclear Fusion, 49(5), p.055006_1 - 055006_9, 2009/05

 Times Cited Count:60 Percentile:89.6(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Status of JT-60SA tokamak under the EU-JA broader approach agreement

Matsukawa, Makoto; Kikuchi, Mitsuru; Fujii, Tsuneyuki; Fujita, Takaaki; Hayashi, Takao; Higashijima, Satoru; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Ide, Shunsuke; Ishida, Shinichi; et al.

Fusion Engineering and Design, 83(7-9), p.795 - 803, 2008/12

 Times Cited Count:17 Percentile:72.99(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Pedestal stability comparison and ITER pedestal prediction

Snyder, P. B.*; Aiba, Nobuyuki; Beurskens, M.*; Groebner, R. J.*; Horton, L. D.*; Hubbard, A. E.*; Hughes, J. W.*; Huysmans, G. T. A.*; Kamada, Yutaka; Kirk, A.*; et al.

Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10

Investigation of intermediate wavelength MHD modes has led to improved understanding of important constraints on the pedestal height and the mechanism for ELMs. The combination of high resolution pedestal diagnostics and a suite of highly efficient stability codes, has made edge stability analysis routine on several major tokamaks, contributing both to understanding, and to experimental planning and performance optimization. Here we present extensive comparisons of observations to predicted edge stability boundaries on several tokamaks, both for the standard ELM regime, and for small ELM and ELM-free regimes. We further use the stability constraint on pedestal height to test models of the pedestal width, and self-consistently combine a simple width model with MHD stability calculations to develop a new predictive model (EPED1) for the pedestal height and width. This model is tested against experimental measurements, and used in initial predictions of the pedestal height for ITER.

Journal Articles

Experimental studies of ITER demonstration discharges

Sips, A. C. C.*; Casper, T. A.*; Doyle, E. J.*; Giruzzi, G.*; Gribov, Y.*; Hobirk, J.*; Hogeweij, G. M. D.*; Horton, L. D.*; Hubbard, A. E.*; Hutchinson, I.*; et al.

Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10

The ITER discharge evolution has been verified in dedicated experiments. Results show that breakdown at E$$<$$ 0.23-0.32 V/m is possible un-assisted (ohmic) for large devices like JET and attainable in all devices with ECRH assist. For the current ramp up, good control of the plasma inductance is obtained using a full bore plasma shape with early X-point formation. Operation of the H-mode reference scenario at q$$_{95}$$ = 3 and the hybrid scenario at q95=4-4.5 during the flat top phase was documented. Specific studies during the flat top phase provide data for the li evolution after the H-mode transition and the li evolution after a back-transition to L-mode. During the ITER ramp down it is important to remain diverted and to reduce the elongation.

Journal Articles

Fitting of the modified Rutherford Equation; A Comparison between ASDEX Upgrade and JT-60U results

Urso, L.*; Zohm, H.*; Fischer, R.*; Isayama, Akihiko; Kamada, Yutaka; ASDEX Upgrade Team; JT-60 Team

Europhysics Conference Abstracts (CD-ROM), 32D, 4 Pages, 2008/00

no abstracts in English

Journal Articles

Comparison of the spatial and temporal structure of type-I ELMs

Kirk, A.*; Asakura, Nobuyuki; Boedo, J. A.*; Beurskens, M.*; Counsell, G. F.*; Eich, T.*; Fundamenski, W.*; Herrmann, A.*; Kamada, Yutaka; Leonard, A. W.*; et al.

Journal of Physics; Conference Series, 123, p.012011_1 - 012011_10, 2008/00

 Times Cited Count:22 Percentile:97.38

A comparison of the spatial and temporal evolution of the filamentary structures observed during type I ELMs is presented from a variety of diagnostics and machines. There is evidence that these filaments can be detected inside the LCFS prior to ELMs. The filaments do not have a circular cross section instead they are elongated in the perpendicular (poloidal) direction and this size appears to increase linearly with the minor radius of the machine. The filaments start rotating toroidally/poloidally with velocities close to that of the pedestal. This velocity then decreases as the filaments propagate radially. It is most likely that the filaments have at least their initial radial velocity when they are far out into the SOL. The dominant loss mechanism is through parallel transport and the transport to the wall is through the radial propagation of these filaments. Measurements of the filament energy content show that each filament contains up to 2.5 % of the energy released by the ELM.

Journal Articles

Control of current profile and instability by radiofrequency wave injection in JT-60U and its applicability in JT-60SA

Isayama, Akihiko; Suzuki, Takahiro; Hayashi, Nobuhiko; Ide, Shunsuke; Hamamatsu, Kiyotaka; Fujita, Takaaki; Hosoyama, Hiroki; Kamada, Yutaka; Nagasaki, Kazunobu*; Oyama, Naoyuki; et al.

AIP Conference Proceedings 933, p.229 - 236, 2007/10

no abstracts in English

58 (Records 1-20 displayed on this page)