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Journal Articles

Experimental study on local interfacial parameters in upward air-water bubbly flow in a vertical 6$$times$$6 rod bundle

Han, X.*; Shen, X.*; Yamamoto, Toshihiro*; Nakajima, Ken*; Sun, Haomin; Hibiki, Takashi*

International Journal of Heat and Mass Transfer, 144, p.118696_1 - 118696_19, 2019/12

 Times Cited Count:4 Percentile:49.6(Thermodynamics)

Journal Articles

Neutronics design of the low aspect ratio tokamak reactor, VECTOR

Nishitani, Takeo; Yamauchi, Michinori*; Nishio, Satoshi; Wada, Masayuki*

Fusion Engineering and Design, 81(8-14), p.1245 - 1249, 2006/02

 Times Cited Count:13 Percentile:68.77(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Neutronic performance of rectangular and cylindrical coupled hydrogen moderators in wide-angle beam extraction of low-energy neutrons

Kai, Tetsuya; Harada, Masahide; Teshigawara, Makoto; Watanabe, Noboru; Kiyanagi, Yoshiaki*; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research A, 550(1-2), p.329 - 342, 2005/09

 Times Cited Count:16 Percentile:74.09(Instruments & Instrumentation)

Neutronic study was performed on coupled hydrogen moderators to maximize time-integrated and pulse-peak intensities of slow neutrons when a large number of beams was required. The total increased with the number of beams, although the average decreased due to a reflector-missing by the beam extraction holes in the reflector. At a large beam extraction angle (25 degree), the spatial distribution of the vector-flux of neutrons was undesirable for a rectangular shape moderator. As an alternative we proposed a cylindrical shape one, resulting in a much improved spatial distribution. In addition, neutronic performance was calculated as a function of the diameter, indicating the optimal diameter was about 140 mm. The cylindrical one gave higher pulse-peak intensities with narrower pulse widths without penalty in time-integrated intensities and pulse decay characteristics, providing a more uniform angle-dependence. Some explanations are given for the difference in the pulse characteristics between the two. We decided to adopt the cylindrical one for the Japanese spallation neutron source.

Journal Articles

Benchmark solution for unstructured geometry PWR problem by method of characteristics using combinatorial geometry

Kugo, Teruhiko; Mori, Takamasa

Proceedings of International Topical Meeting on Mathematics and Computation, Supercomputing, Reactor Physics and Nuclear and Biological Applications (M&C 2005) (CD-ROM), 10 Pages, 2005/09

A new deterministic transport code based on the method of characteristics (MOC) has been developed for heterogeneous transport calculations in core design of innovative reactors which have complex structures. We have investigated the capability of the MOC code for general geometry with an unstructured geometry PWR problem. The comparison of the results with accurate Monte Carlo calculation results by GMVP has confirmed that the MOC code produces satisfactory results and has a capability to treat unstructured geometry.

JAEA Reports

MVP/GMVP 2; General purpose Monte Carlo codes for neutron and photon transport calculations based on continuous energy and multigroup methods

Nagaya, Yasunobu; Okumura, Keisuke; Mori, Takamasa; Nakagawa, Masayuki

JAERI 1348, 388 Pages, 2005/06

JAERI-1348.pdf:2.02MB

To realize fast and accurate Monte Carlo simulation of neutron and photon transport problems, two vectorized Monte Carlo codes MVP and GMVP have been developed at JAERI. MVP is based on the continuous energy model and GMVP is on the multigroup model. Compared with conventional scalar codes, these codes achieve higher computation speed by a factor of 10 or more on vector supercomputers. Both codes have sufficient functions for production use by adopting accurate physics model, geometry description capability and variance reduction techniques. The first version of the codes was released in 1994. They have been extensively improved and new functions have been implemented. The major improvements and new functions are (1) capability to treat the scattering model expressed with File 6 of the ENDF-6 format, (2) time-dependent tallies, (3) reaction rate calculation with the pointwise response function, (4) flexible source specification, etc. This report describes the physical model, geometry description method used in the codes, new functions and how to use them.

Journal Articles

Steady-state operation of high-beta/low aspect ratio tokamak reactor with bootstrap current

Sengoku, Seio

Purazuma, Kaku Yugo Gakkai-Shi, 80(11), p.940 - 943, 2004/11

Recent spherical tokamak (ST) experiments exhibit many advantageous results including plasma start-up without center solenoid, higher fraction of non-inductive current, formation of internal thermal-barrier as seen on conventional tokamak. In order to reflect these efforts on the design of so called "non-inductive steady-state (SS) operation scenario" and "current ramp-up scenario" of low-aspect reactor, fractions of bootstrap current and neutral-beam-driven current on VECTOR-OPT reactor are estimated. The operation with this SS scenario is shown to be feasible if the normalized beta, $$beta$$n, is raised to grater than 5 typical in ST.

Journal Articles

Design of the high-T$$_{c}$$ superconducting TF coil for the tight aspect ratio Tokamak power reactor (VECTOR)

Ando, Toshinari*; Nishio, Satoshi; Yoshimura, Hideto*

IEEE Transactions on Applied Superconductivity, 14(2), p.1481 - 1484, 2004/06

 Times Cited Count:8 Percentile:44.28(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Public acceptance of a low aspect ratio tokamak reactor from the point of view of waste

Tobita, Kenji

Denki Gakkai Kenkyukai Shiryo, Purazuma Kenkyukai (PST-03-37$$sim$$44), p.19 - 22, 2003/09

no abstracts in English

Journal Articles

Development of fission source acceleration method for slow convergence in criticality analyses by using matrix eigenvector applicable to spent fuel transport cask with axial burnup profile

Kuroishi, Takeshi; Nomura, Yasushi

Journal of Nuclear Science and Technology, 40(6), p.433 - 440, 2003/06

 Times Cited Count:1 Percentile:11.39(Nuclear Science & Technology)

Effective source acceleration method is studied in criticality safety analysis for realistic spent fuel transport cask. Various axial burnup profiles based on in-core flux measurements are proposed in the OECD/NEA/BUC benchmark Phase II-C. In some cases, calculations by ordinary Monte Carlo method show very slow convergence of fission source distribution, and unacceptably large skipped cycles are needed. The matrix eigenvector calculation that has been developed and incorporated in the ordinary Monte Carlo calculation to improve the slow convergence is applied to the benchmark. The efficiency of this method depends on the precision of matrix elements. In a certain stage of insufficient convergence of fission source distribution, especially for this benchmark of very slow convergence, more acceleration procedure causes anomalous results because of large statistical fluctuations of matrix elements corresponding to low source levels. Therefore, we propose effective source acceleration method with less calculation time than increasing histories for the estimation of matrix elements.

Journal Articles

Fast vector computation of the characteristics method

Kugo, Teruhiko

Journal of Nuclear Science and Technology, 39(3), p.256 - 263, 2002/03

 Times Cited Count:3 Percentile:24.34(Nuclear Science & Technology)

Two vector computation algorithms; an odd-even sweep (OES) method and an independent sequential sweep (ISS) method, have been developed for the characteristics method to solve the neutron transport equation in a heterogeneous geometry. They realize long vector lengths without recursive operations for effective use of vector computers. Their efficiency has been investigated to a realistic fuel assembly calculation. For both methods, a vector computation is 15 times faster than a scalar computation. From a viewpoint of a comparison between the OES and ISS methods, the ISS method is superior to the OES method because the ISS method shows a faster convergence and saves a computer memory without reducing a computation speed.

Journal Articles

Vector performance prediction of kernel loops on Earth Simulator

Yokokawa, Mitsuo; Saito, Minoru*; Hagiwara, Takashi*; Isobe, Yoko*; Jinguji, Satoshi*

Nihon Keisan Kogakkai Rombunshu, 4, p.31 - 36, 2002/00

Earth simulator is a distributed memory parallel system which consists of 640 processor nodes connected by a full crossbar network. Each processor node is a shared memory system which is composed of eight vector processors. The total peak performance and main memory capacity are 40Tflops and 10TB, respectively. A performance prediction system GS$$^3$$ for the Earth Simulator has been developed to estimate sustained performance of programs. To validate accuracy of vector performance prediction by the GS$$^3$$, the processing times for three groups of kernel loops estimated by the GS$$^3$$ are compared with the ones measured on SX-4. It is found that the absolute relative errors of the processing time are 0.89%,1.42% and 6.81% in average for three groups. The sustained performance of three groups on a processor of the Earth Simulator have been estimated by the GS$$^3$$ and those performance are 5.94Gflops,3.76Gflops and 2.17Gflops in average.

JAEA Reports

Fast computation of the characteristics method on vector computers

Kugo, Teruhiko

JAERI-Research 2001-051, 39 Pages, 2001/11

JAERI-Research-2001-051.pdf:2.04MB

Fast computation of the characteristics method to solve the neutron transport equation in a heterogeneous geometry has been studied. Two vector computation algorithms; an odd-even sweep (OES) method and an independent sequential sweep (ISS) method have been developed and their efficiency to a typical fuel assembly calculation has been investigated. For both methods, a vector computation is 15 times faster than a scalar computation. From a viewpoint of comparison between the OES and ISS methods, the ISS method is superior to the OES method because the ISS method shows a faster convergence and saves a computer memory without reducing a computation speed. In the vector computation, a table-look-up method to reduce computation time of an exponential function saves only 20% of a whole computation time. Both the coarse mesh rebalance method and the Aitken acceleration method are effective as acceleration methods for the characteristics method, a combination of them saves 70-80% of outer iterations compared with a free iteration.

JAEA Reports

Vectorization, parallelization and porting of nuclear codes (vectorization and parallelization); Progress report fiscal 1999

Adachi, Masaaki*; Ishizuki, Shigeru*; Ogasawara, Shinobu*; Kume, Etsuo; Yatake, Yoichi*; Nemoto, Toshiyuki*; Kawasaki, Nobuo*; Kawai, Wataru*

JAERI-Data/Code 2000-043, 220 Pages, 2001/02

JAERI-Data-Code-2000-043.pdf:7.39MB

no abstracts in English

JAEA Reports

Examination of concept of next generation computer progress report 1999

Higuchi, Kenji; Hasegawa, Yukihiro*; Hirayama, Toshio

JAERI-Review 2000-019, 70 Pages, 2000/12

JAERI-Review-2000-019.pdf:1.89MB

no abstracts in English

Journal Articles

Development of regional atmospheric dynamic and air pollution models for nuclear emergency response system WSPEEDI

Furuno, Akiko; Yamazawa, Hiromi; Lee, S.; Tsujita, Yuichi; Takemiya, Hiroshi*; Chino, Masamichi

Proceedings of 4th International Conference on Supercomputing in Nuclear Applications (SNA 2000) (CD-ROM), 7 Pages, 2000/09

no abstracts in English

JAEA Reports

Vectorization, parallelization and porting of nuclear codes (Vectorization and parallelization); Progress report fiscal 1998

Ishizuki, Shigeru*; Ogasawara, Shinobu*; Kawai, Wataru*; Nemoto, Toshiyuki*; Kume, Etsuo; Adachi, Masaaki*; Kawasaki, Nobuo*; Yatake, Yoichi*

JAERI-Data/Code 2000-018, p.217 - 0, 2000/03

JAERI-Data-Code-2000-018.pdf:6.35MB

no abstracts in English

JAEA Reports

Vectorization, parallelization and porting of nuclear codes on the VPP500 system (Vectorization); Progress report fiscal 1997

*; *; *; *; *; Ogasawara, Shinobu*; Adachi, Masaaki*; *; Kume, Etsuo

JAERI-Data/Code 99-026, 91 Pages, 1999/05

JAERI-Data-Code-99-026.pdf:2.9MB

no abstracts in English

JAEA Reports

Vectorization, parallelization and porting of nuclear codes on the VPP500 system (parallelization); Progress report fiscal 1997

*; *; *; *; *; *; Ogasawara, Shinobu*; Adachi, Masaaki*; Kume, Etsuo

JAERI-Data/Code 99-020, 168 Pages, 1999/03

JAERI-Data-Code-99-020.pdf:5.34MB

no abstracts in English

JAEA Reports

MOSRA-Light; High speed three-dimensional nodal diffusion code for vector computers

Okumura, Keisuke

JAERI-Data/Code 98-025, 243 Pages, 1998/10

JAERI-Data-Code-98-025.pdf:10.15MB

no abstracts in English

JAEA Reports

Vectorization, parallelization and porting of nuclear codes on the VPP500 system (parallelization;Progress report fiscal 1996

*; *; *; *; *; *; Harada, Hiro; ; Kume, Etsuo;

JAERI-Data/Code 97-052, 160 Pages, 1997/12

JAERI-Data-Code-97-052.pdf:4.17MB

no abstracts in English

97 (Records 1-20 displayed on this page)