研究者詳細 - 山本　章夫

論文 - 山本　章夫

分割表示 487 件中 141 - 160 件目／全件表示 >>

A Simple Treatment of Bowed Assembly Gap Through Correction of Cross Section 査読有り

A. Yamamoto, T. Endo, K. Yamamoto, Y. Ohoka, H. Nagano

Trans. Am. Nucl. Soc. 119 巻頁： 1199-1202 2018年11月

Transport Consistent Diffusion Coefficient for CMFD Acceleration 査読有り

A. Yamamoto, T. Endo

Trans. Am. Nucl. Soc. 119 巻頁： 1179-1181 2018年11月

Estimation of Subcriticality in Dollar Units Based on Integral Method for Arbitrary State-Change in Subcritical System 査読有り

A. Nonaka, T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc. 119 巻頁： 1112-1115 2018年11月

Surrogate Model of Severe Accident Analysis Code for SBO Aiming Probabilistic Safety Margin Analysis 査読有り

M. Matsushita, T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc. 119 巻頁： 900-903 2018年11月

Estimation of Subcriticality using Particle Filter Method 査読有り

T. Ikeda, T. Kimura, T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc. 118 巻頁： 851-854 2018年6月

Quantification of Modeling Approximation Error of Pin-Cell Calculation Using Kriging and Principal Component Analysis 査読有り

T.Hanai, A. Yamamoto, T. Endo, K. Yamamoto, Y. Ohoka, H. Nagano

Trans. Am. Nucl. Soc. 118 巻頁： 875－878 2018年6月

Inverse Estimation Methods of Unknown Radioactive Source for Fuel Debris Search 査読有り

S. Sugaya, T. Endo, A. Yamamoto

Proc. PHYSOR201 頁： [USB-DRIVE] 2018年4月

Estimation of Subcriticality in Dollar Units using Integral Method for Subcritical System 査読有り

A. Nonaka, T. Endo, A. Yamamoto

Proc. PHYSOR2018 頁： [USB-DRIVE] 2018年4月

Cache Efficient Flux Region Assignment for the Method of Characteristics 査読有り

A. Yamamoto, A. Giho, T. Endo

Proc. PHYSOR2018 頁： [USB-DRIVE] 2018年4月

Estimation of Region-Wise Even-Parity Discontinuity Factor for MOC Through Iterative Procedure 査読有り

A. Yamamoto, A. Giho, T. Endo

Proc. PHYSOR2018 頁： [USB-DRIVE] 2018年4月

Development of Reduced Order Model of Severe Accident Analysis Code for Probabilistic Safety Margin Analysis

M. Matsushita, T. Endo, A. Yamamoto, T. Kitao

Proc. PHYSOR2018 頁： [USB-DRIVE] 2018年4月

Sensitivity Coefficient Analysis of Omega-Eigenvalue based on First-Order Perturbation Theory 査読有り

頁： [USB-DRIVE] 2018年4月

Estimation of sensitivity coefficient based on lasso-type penalized linear regression

Katano, R; Endo, T; Yamamoto, A; Tsujimoto, K

JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 55 巻 ( 10 ) 頁： 1099 - 1109 2018年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Science and Technology

We proposed the penalized regression ‘adaptive smooth-lasso’ for the estimation of sensitivity coefficients of the neutronics parameters. The proposed method utilizes the variation of the microscopic cross-sections and the neutronics parameters obtained by random sampling. The weighted penalty term of the proposed method is more appropriate for the estimation of the sensitivity of neutronics parameters to the microscopic cross-section than that of the conventional methods. In a numerical verification calculation, sensitivity coefficients of k<inf>eff</inf> of an accelerator-driven system are estimated using the proposed method, the conventional penalized regression, and the direct method. Comparison of these results indicates that the proposed method is superior to the conventional penalized linear regression from the viewpoint of reproduction of the reference sensitivity coefficients obtained by the direct method. Through the verification calculations, the proposed method can be a candidate for a practical method to estimate the sensitivity coefficients with low calculation cost.

DOI： 10.1080/00223131.2018.1479988

Web of Science

Scopus

Radially and azimuthally dependent resonance self-shielding treatment for general multi-region geometry based on a unified theory

Koike, H; Kirimura, K; Yamaji, K; Kosaka, S; Yamamoto, A

JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 55 巻 ( 1 ) 頁： 41 - 65 2018年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Science and Technology

A unified resonance self-shielding method, which can treat general sub-divided fuel regions, is developed for lattice physics calculations in reactor physics field. In a past study, a hybrid resonance treatment has been developed by theoretically integrating equivalence theory and ultra-fine-group slowing-down calculation. It can be applied to a wide range of neutron spectrum conditions including low moderator density ranges in severe accident states, as long as each fuel region is not sub-divided. In order to extend the method for radially and azimuthally sub-divided multi-region geometry, a new resonance treatment is established by incorporating the essence of sub-group method. The present method is composed of two-step flux calculation, i.e. ‘coarse geometry + fine energy’ (first step) and ‘fine geometry + coarse energy’ (second step) calculations. The first step corresponds to a hybrid model of the equivalence theory and the ultra-fine-group calculation, and the second step corresponds to the sub-group method. From the verification results, effective cross-sections by the new method show good agreement with the continuous energy Monte-Carlo results for various multi-region geometries including non-uniform fuel compositions and temperature distributions. The present method can accurately generate effective cross-sections with short computation time in general lattice physics calculations.

DOI： 10.1080/00223131.2017.1384704

Web of Science

Scopus

Dimension-reduced cross-section adjustment method based on minimum variance unbiased estimation

Yokoyama, K; Yamamoto, A; Kitada, T

JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 55 巻 ( 3 ) 頁： 319 - 334 2018年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Science and Technology

A new formulation of the cross-section adjustment methodology with the dimensionality-reduction technique has been derived in the light of the fact that it is often used under the condition of ill-posed problem, where the number of integral experimental quantities is less than the number of adjusted nuclear data parameters. This new formulation is proposed as the dimension-reduced conventional cross-section adjustment method (DRCA). The derivation of DRCA is based on the minimum variance unbiased estimation (MVUE), and the assumption of normal distribution is not used. The result of DRCA depends on a user-defined matrix that determines the dimension-reduced feature subspace. We examined three variations of DRCA, namely, DRCA1, DRCA2, and DRCA3, which employ (1) the nuclear data covariance matrix as the user-defined matrix, (2) the sensitivity coefficient matrix postmultiplied by the nuclear data covariance matrix, and (3) the sensitivity coefficient matrix, respectively. Mathematical investigation and numerical verification revealed that DRCA2 is equivalent to the currently widely used cross-section adjustment method. Moreover, DRCA3 is found to be identical to the cross-section adjustment method based on MVUE, which has been proposed in the previous study.

DOI： 10.1080/00223131.2017.1397563

Web of Science

Scopus

Utilization of Region-wise Even-Parity Discontinuity Factor to Reduce Discretization Error of MOC 査読有り

A. Yamamoto, A. Giho, T. Endo

Nuclear Science and Engineering 193 巻頁： 253-268 2018年

Flux Region Assignment Method using Ray Trace Information for the Method of Characteristics to Improve Cache Efficiency

A. Yamamoto, A. Giho, T. Endo

Nuclear Science and Engineering 192 巻頁： 243-250 2018年

Estimation of Sensitivity Coefficient based on Lasso-type Penalized Linear Regression 査読有り

R. Katano, T. Endo, A. Yamamoto, K. Tsujimoto

JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 55 巻頁： 1099-1109 2018年

Flux Region Assignment Method Using Ray Trace Information for the Method of Characteristics to Improve Cache Efficiency

Yamamoto, A; Giho, A; Endo, T

NUCLEAR SCIENCE AND ENGINEERING 192 巻 ( 3 ) 頁： 240 - 253 2018年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Science and Engineering

A flux region assignment algorithm to increase cache efficiency for the method of characteristics (MOC) is proposed. In order to minimize the stride of memory access, flux region identifications are assigned based on the ray trace sequence during the MOC calculation. The present method is implemented in the three-dimensional transport code GENESIS and its performance is confirmed through verification calculations ranging from single pressurized water reactor (PWR) fuel assembly to PWR full-core benchmark problems. Quantitative comparison of cache efficiency is carried out and the present method shows improved cache efficiency, which results in a reduction in computation time. The present method can reduce computational time by improving cache efficiency while suppressing memory requirement.

DOI： 10.1080/00295639.2018.1501978

Web of Science

Scopus

リスク評価とマネジメントに関するアジアシンポジウム開催報告

山口彰, 山本章夫, 成宮祥介

日本原子力学会誌ATOMOΣ 60 巻 ( 6 ) 頁： 362 - 363 2018年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本原子力学会

<p>　リスクに関する国際シンポジウムは，日中韓を中心に横浜で開催された。20年ほど前に日韓で始まった日韓PSAワークショップにその起源をおくもので，原子力施設に関するリスク評価の専門家が一堂に会し，充実した意見交換，議論が行われた。リスクの本格活用に臨む我が国としては多くの知見を得たシンポジウムとなった。</p>

DOI： 10.3327/jaesjb.60.6_362

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