研究者詳細 - 遠藤　知弘

MISC - 遠藤　知弘

分割表示 188 件中 121 - 140 件目／全件表示 >>

GENESIS - A Transport Solver in Three-Dimensional Heterogeneous Geometry Based on the LEAF Method 査読有り国際誌

A. Yamamoto, A. Giho, T. Endo

Proc. PHYSOR2016 頁： 4080 - 4106 2016年5月

記述言語：英語掲載種別：研究発表ペーパー・要旨（国際会議）出版者・発行元：American Nuclear Society

A heterogeneous transport solver in three dimensional geometry, GENESIS, is being developed incorporating recent developments of the method of characteristics (MOC) in three dimensional geometry. The Legendre Expansion of Angular Flux (LEAF) method is implemented in the GENESIS code, in which neutron transport is calculated in two-dimensional "characteristics planes" rather than in one-dimensional characteristics lines adopted in the conventional approach of 3D MOC. Unlike the planner MOC method that combines 2D MOC calculations through axial leakages, the GENESIS code explicitly considers angular and spatial dependence of outgoing and incoming angular fluxes between axial planes. Thus the GENESIS code eliminates a crucial approximation used in the planner MOC method. The GENESIS code can handle flexible shape of objects in rectangular or hexagonal geometry. Two-level, multi-group generalized coarse mesh rebalance (GCMR) acceleration method is adopted for efficient convergence of neutron transport calculation. Performance of the GENESIS code is verified through various benchmark calculations. The calculation results indicate the fidelity of the GENESIS code.

Theoretical Expression of Area Ratio Method using Detected-Neutron Multiplication Factor 査読有り国際誌

T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc.113 巻頁： 1208 - 1211 2015年11月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究発表ペーパー・要旨（国際会議）出版者・発行元：American Nuclear Society

In the present paper, the area ratio method is expressed by the detected-neutron multiplication factor kdet. In addition, an appropriate detector position is discussed by investigating the difference between kdet and the effective neutron multiplication factor keff.

Application of Data Assimilation based on Bayesian Theory to Subcriticality Measurements using Area Ratio Method 査読有り国際誌

K. Maeno, T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc.113 巻頁： 1282 - 1286 2015年11月

Underestimation of Statistical Uncertainty of Monte Carlo Method with Non-Analog of Fission Source Sampling 査読有り国際誌

K. Hayashi, T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc.113 巻頁： 1153 - 1157 2015年11月

Uncertainty Estimation of Analysis Model using the Data Assimilation Method 査読有り国際誌

K. Kinoshita, T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc.113 巻頁： 1141 - 1143 2015年11月

Development of a Simplified Estimation Method on Severe Accident Progression in PWR for Education 査読有り国際誌

S. Otsuki, T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc.113 巻頁： 855 - 858 2015年11月

Application of Partially-Converged Solution of Assembly Calculation for Core Sensitivity Analysis based on Reduced Order Modeling 査読有り国際誌

R. Katano, A. Yamamoto, T. Endo

Trans. Am. Nucl. Soc.113 巻頁： 1161 - 1164 2015年11月

Discontinuity Factors for Simplified P3 Theory 査読有り

A. Yamamoto, T. Endo

Proc. of Reactor Physics Asia 2015CD-ROM 巻 2015年9月

Reactor Physics Activities in Nagoya University 査読有り

A. Yamamoto, T. Endo

Proc. of Reactor Physics Asia 2015CD-ROM 巻 2015年9月

Development of New Statistical Geometry Model using the Delta-tracking Method 査読有り

T. Koide, T. Endo, A. Yamamoto

Proc. of Reactor Physics Asia 2015CD-ROM 巻 2015年9月

Development of Core Sensitivity Analysis Based on Reduced-Order Modeling using Assembly Calculations 査読有り国際誌

R. Katano, A. Yamamoto, T. Endo

Trans. Am. Nucl. Soc.112 巻頁： 715 - 718 2015年6月

Efficient Execution of Monte Carlo Simulation Based on Pseudo-Scattering using GPU 査読有り国際誌

T. Okubo, T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc.112 巻頁： 648 - 651 2015年6月

Comparison of Spatial Source Expansion Methods in the Three Dimensional Transport Method LEAF 査読有り国際誌

Y. Kato, T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc.111 巻頁： 1405 - 1408 2014年11月

Statistical Error Estimation using Bootstrap Method for the Feynman-α Method 査読有り国際誌

T. Endo, T. Shiozawa, A. Yamamoto, C.H. Pyeon, T. Yagi

Trans. Am. Nucl. Soc.111 巻頁： 1204 - 1207 2014年11月

Estimation of Sensitivity Coefficient using Random Sampling and L1-norm Minimization 査読有り国際誌

T. Watanabe, T. Endo, A. Yamamoto, Y. Kodama, Y. Ohoka, T. Ushio

Trans. Am. Nucl. Soc.111 巻頁： 1391 - 1394 2014年11月

Confidence Interval Estimation by Bootstrap Method for Uncertainty Quantification using Random Sampling Method 査読有り国際誌

T. Endo, T. Watanabe, A. Yamamoto

Proc. PHYSOR2014CD-ROM 巻頁： 1084668 2014年9月

Improvement of a Convergence Technique for MOC Calculation with Large Negative Self-Scattering Cross Section 査読有り国際誌

M. Tabuchi, M. Tatsumi, A. Yamamoto, T. Endo

Proc. PHYSOR2014CD-ROM 巻頁： 1105664 2014年9月

記述言語：英語掲載種別：研究発表ペーパー・要旨（国際会議）出版者・発行元：Japan Atomic Energy Agency

In the method of characteristics, convergence behavior of inner iteration would be degraded by the transport correction. A previous study revealed that large negative self-scattering cross section due to the transport correction worsens convergence of inner iteration. In order to resolve this issue, a technique to improve the convergence behavior based on the successive over relaxation (SOR) method was proposed in the previous study. However, considerable calculation time is necessary to estimate the optimum acceleration factor for the SOR method especially in large scale geometries. In order to address this drawback, a fast estimation scheme of the acceleration factors is proposed in this study. The present approach can provide acceleration factors which ensure convergence of iterative calculation. In the present approach, the equation to obtain the appropriate acceleration factor is derived by using Gerschgorin’s theorem. Based on the equation, the acceleration factors can be easily obtained in each energy group with negligible calculation time. Verification calculations are performed in various critical experiments, in which degradation of convergence by the transport correction is significant. When the transport correction is used without the SOR method, all iterative calculations diverged. On the other hand, when the SOR method with the acceleration factors based on the present approach is applied, convergent solutions are successfully obtained in all cases. From these results, validity of the present approach is confirmed.

DOI： 10.11484/jaea-conf-2014-003

A Multi-Level Parallel Computation of Reactor Cores using GPU for Loading Pattern Optimization 査読有り国際誌

T. Okubo, T. Endo, A. Yamamoto

Proc. PHYSOR2014CD-ROM 巻頁： 1101184 2014年9月

記述言語：英語掲載種別：研究発表ペーパー・要旨（国際会議）出版者・発行元：Japan Atomic Energy Agency

Efficient and rapid computation of multiple loading patterns using GPU is studied aiming application to loading pattern optimization of LWR. The loading pattern has significant impacts on safety and economy of a reactor. However, design of loading pattern is a combinatorial optimization problem, thus it is computationally intensive task. In order to address this issue, efficient and rapid computation method of loading patterns using massively parallel computing capability of GPU is studied in the present paper. Though GPU has higher computational performance than CPU, but different computational algorithm and coding approach are necessary to maximize the performance of GPU, due to different architecture of GPU. In the present study, a multi-level parallel computing approach is examined considering hardware architecture of GPU, i.e., parallel computing is carried out not only in spatial mesh-wise, but also in loading pattern-wise. In other words, multiple loading patterns are simultaneously computed and domain (mesh-wise) decomposition is applied to each loading pattern. With the present approach, computational efficiency using GPU is approximately four times higher than that of CPU. The present core analysis algorithm can be used for screening of poor loading patterns in optimization process.

DOI： 10.11484/jaea-conf-2014-003

Development of Legendre Expansion of Angular Flux Method for 3D-MOC Calculation 査読有り国際誌

Y. Kato, T. Endo, A. Yamamoto

Proc. PHYSOR2014CD-ROM 巻頁： 1106157 2014年9月

記述言語：英語掲載種別：研究発表ペーパー・要旨（国際会議）出版者・発行元：Japan Atomic Energy Agency

A three-dimensional transport calculation method, Legendre Expansion of Angular Flux Method (LEAF method) has been proposed for practical MOC calculations in three-dimensional geometry. In the LEAF method, transport calculation is carried out on "characteristics planes(CP)" rather than conventional ray traces, whose concept is similar to that of the ASMOC3D method. By utilizing the characteristics plane, required memory and computational load are significantly reduced. Each characteristics plane forms rectangular regions, thus efficient transport calculation scheme based on transmission probability can be adopted. Consequently, the LEAF method can practically perform MOC calculation in three-dimensional geometry. In the LEAF method, spatial distribution of incoming, outgoing and average angular fluxes in a CP are expressed as a series of the Legendre polynomials in order to accurately capture their spatial dependence. Calculation results in a test problem indicate the accuracy and effectiveness of the LEAF method.

DOI： 10.11484/jaea-conf-2014-003

Investigation on Subcriticality Measurement using Inherent Neutron Source in Nuclear Fuel 査読有り国際誌

T. Shiozawa, T. Endo, A. Yamamoto, C.H. Pyeon, T. Yagi

Proc. PHYSOR2014CD-ROM 巻頁： 1086633 2014年9月

担当区分：責任著者記述言語：英語掲載種別：研究発表ペーパー・要旨（国際会議）出版者・発行元：Japan Atomic Energy Agency

The subcriticality measurement techniques using inherent neutron source are investigated in this study. In facilities where nuclear fuel is treated, it is considered to install a real-time subcriticality monitoring system. However, it is often unfavorable or impractical to bring an external neutron source into a nuclear facility to carry out subcriticality measurement. Thus, we focus on the inherent neutron source in nuclear fuel such as spontaneous fission and (alpha, n) reaction. By utilizing the inherent neutron source, the subcriticality measurement technique, which does not introduce an external neutron source, can be realized. In this study, the Feynman-alpha method and the neutron source multiplication (NSM) method are chosen as techniques which can be carried out only with the inherent neutron source, and have affinities with a real-time monitoring system. In the Kyoto University Critical Assembly (KUCA), subcriticality measurement experiments of these two techniques were carried out. From the experimental result, it is confirmed that both techniques can be carried out only with the inherent neutron source. It is noted that, however, measured values of subcriticality by both methods show different trends. While the subcriticality measured by the Feynman-alpha method is fairly constant among detectors, the measured value does not agree with that obtained by the pulsed neutron source (PNS) method, in deep subcritical systems. On the other hand, the subcriticality measured by the NSM method show significant dependence on detectors. However, the measurement values by the NSM method using detectors at appropriate position agree with values by the PNS method even in deep subcritical systems.

DOI： 10.11484/jaea-conf-2014-003

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