研究者詳細 - 山本　章夫

論文 - 山本　章夫

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Inverse estimation methods of unknown radioactive source for fuel debris search

Sugaya S., Endo T., Yamamoto A.

International Conference on Physics of Reactors, PHYSOR 2018: Reactor Physics Paving the Way Towards More Efficient Systems Part F168384-4 巻頁： 2632 - 2643 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：International Conference on Physics of Reactors, PHYSOR 2018: Reactor Physics Paving the Way Towards More Efficient Systems

To identify distribution of fuel debris remaining in the reactor vessel and/or the containment vessel of Fukushima Daiichi NPS, we focused on the inverse estimation of radioactive source distribution using measured values of radiation counts. The Maximum Likelihood-Expectation Maximization (ML-EM) method and the Moore-Penrose Matrix Inverse (MPMI) method are examined. The ML-EM method has been used for image reconstruction of computed tomography, and the MPMI method is one of the solution methods for simultaneous linear equations. A simple calculation model simulating the containment vessel were constructed including detectors and radiation sources. In actual situation, sufficient number of radiation measurement positions would not be available owing to the complexity of structures inside the containment vessel. Thus, the number of radiation measurement points (number of constraints) are smaller than positions of radiation source. It means that an underdetermined inverse problem should be solved. The detection probability of radiation (neutron or photon) is calculated by the adjoint transport calculation since the detection probability is used as the coupling coefficient between a radiation count at a detector and a radioactive source. Result of estimation using the ML-EM or the MPMI method indicates that the accuracy of estimation depends on the distance between a radiation source and a detector, and radiation count measurement positions. The ML-EM and the MPMI methods show different prediction accuracy depending on the calculation condition. It is found that the detectors should be placed at vicinity of radiation sources of interest and that the applicability of the inverse estimation does not strongly depend on the radioactivity distribution.

Scopus

Quantification of modeling approximation error of pin-cell calculation using kriging and principal component analysis

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

Transactions of the American Nuclear Society 118 巻頁： 875 - 878 2018年

Quantification of modeling approximation error of pin-cell calculation using kriging and principal component analysis

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

AISTech - Iron and Steel Technology Conference Proceedings 2018-May 巻頁： 875 - 878 2018年

Estimation of Modeling Approximation Error of Core Analysis Using the Surrogate Model with Kriging 査読有り

Tomomi Hanai, Tomohiro Endo, Yasuhiro Kodama, Yasunori Ohoka, Akio Yamamoto

rans. Am. Nucl. Soc. 117 巻頁： 1269-1272 2017年11月

Application of the GENESIS Code to the Kobayashi 3D Benchmark Problem 査読有り

Akio Yamamoto, Akinori Giho, Tomohiro Endo

Trans. Am. Nucl. Soc. 117 巻頁： 1403-1406 2017年11月

Recent developments in the GENESIS code based on the Legendre polynomial expansion of angular flux method Open Access

Yamamoto, A; Giho, A; Endo, T

NUCLEAR ENGINEERING AND TECHNOLOGY 49 巻 ( 6 ) 頁： 1143 - 1156 2017年9月

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 Engineering and Technology

This paper describes recent development activities of the GENESIS code, which is a transport code for heterogeneous three-dimensional geometry, focusing on applications to reactor core analysis. For the treatment of anisotropic scattering, the concept of the simplified Pn method is introduced in order to reduce storage of flux moments. The accuracy of the present method is verified through a benchmark problem. Next, the iteration stability of the GENESIS code for the highly voided condition, which would appear in a severe accident (e.g., design extension) conditions, is discussed. The efficiencies of the coarse mesh finite difference and generalized coarse mesh rebalance acceleration methods are verified with various stabilization techniques. Use of the effective diffusion coefficient and the artificial grid diffusion coefficients are found to be effective to stabilize the acceleration calculation in highly voided conditions.

DOI： 10.1016/j.net.2017.06.016

Open Access

Web of Science

Scopus

Uncertainty Quantification of Activation Due to Cross Section Data in Neutron Shielding Calculation 査読有り

Kimihiro Yokoi,Tomohiro Endo,Akio Yamamoto,Ryoji Mizuno,Yoshio Kimura

Proc. 2017 International. Cogress on Advances in Nuclear Power Plants 2017年4月

Application of Bias Factor Method using Random Sampling Technique for Critical Eigenvalue Prediction of BWR 査読有り

Motohiro Ito,Tomohiro Endo,Akio Yamamoto,Yusuke Kuroda,Takashi Yoshii

Proc. 2017 International Cogress on Advances in Nuclear Power Plants 2017年4月

Development of Dynamic Probabilistic Risk Assessment Model for PWR using Simplified Plant Simulation Method 査読有り

Shohei Otsuki,Tomohiro Endo,Akio Yamamoto

Proc. 2017 International Cogress on Advances in Nuclear Power Plants 2017年4月

Development of GENESIS, a Three-dimensional Heterogeneous Transport Code based on the LEAF Method 査読有り

Akio Yamamoto,Akinori Giho,Tomohiro Endo

Proc. Int. Conf. on Math. and Comp. Methods Applied to Nucl. Sci. & Eng. (M&C2017) 2017年4月

Theoretical Discussion of Statistical Error of Variance-to-Mean Ratio 査読有り

Tomohiro Endo,Akio Yamamoto

Proc. Int. Conf. on Math. and Comp. Methods Applied to Nucl. Sci. & Eng. (M&C2017) 2017年4月

Inverse Estimation of Unknown Radioactive Source using Detection Probability by Adjoint Calculation

Shinji Sugaya,Tomohiro Endo,Akio Yamamoto

Proc. Int. Conf. on Math. and Comp. Methods Applied to Nucl. Sci. & Eng. (M&C2017) 2017年4月

Uncertainty Quantification of Bell Factor for Sjöstrand Method due to Cross-section Data for MA core 査読有り

Toshiki Kimura,Tomohiro Endo,Akio Yamamoto

Proc. Int. Conf. on Math. and Comp. Methods Applied to Nucl. Sci. & Eng. (M&C2017) 2017年4月

A coupling model for the two-stage core calculation method with subchannel analysis for boiling water reactors

Mitsuyasu, T; Aoyama, M; Yamamoto, A

ANNALS OF NUCLEAR ENERGY 102 巻頁： 77 - 84 2017年4月

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

The two-stage core analysis method is widely used for BWR core analysis. The purpose of this study is to develop a core analysis model coupled with subchannel analysis within the two-stage calculation scheme using an assembly-based thermal-hydraulics calculation in the core analysis. The model changes the 2D lattice physics scheme, and couples with 3D subchannel analysis which evaluates the thermal-hydraulics characteristics within the coolant flow area divided as some subchannel regions. In order to couple with these two analyses, some BWR fuel assembly parameters are assumed and verified. The developed model is evaluated for the heterogeneous problem with and without a control rod. The present model is especially effective for the control rod inserted condition. The present model can incorporate the subchannel effect into the current two-stage core calculation method.

DOI： 10.1016/j.anucene.2016.11.045

Web of Science

Scopus

GENESIS: A Three-Dimensional Heterogeneous Transport Solver Based on the Legendre Polynomial Expansion of Angular Flux Method

Yamamoto, A; Giho, A; Kato, Y; Endo, T

NUCLEAR SCIENCE AND ENGINEERING 186 巻 ( 1 ) 頁： 1 - 22 2017年4月

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 heterogeneous transport solver in three-dimensional (3-D) geometry, GENESIS, is developed incorporating recent developments in the method of characteristics (MOC) in 3-D geometry. The Legendre Polynomial Expansion of Angular Flux (LEAF) method is implemented in the GENESIS code, in which neutron transport is calculated in two-dimensional (2-D) characteristics planes rather than in one-dimensional characteristics lines adopted in the conventional approach of 3-D MOC. Unlike the planar MOC method that combines 2-D 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 planarMOC method: No approximation is used for axial leakage treatment. The GENESIS code can handle flexible shapes of objects in rectangular or hexagonal geometry. A two-level, multigroup generalized coarse mesh rebalance 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 based on the LEAF method.

DOI： 10.1080/00295639.2016.1273002

Web of Science

Scopus

Estimation of modeling approximation errors using data assimilation with the minimum variance approach

Yamamoto, A; Kinoshita, K; Endo, T

JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 54 巻 ( 4 ) 頁： 459 - 471 2017年4月

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

In this paper, we estimate prediction errors owing to approximations in calculation models (modeling approximation error) using the data assimilation method. Correlations between the modeling approximation error and neutronics parameters obtained through calculations are evaluated in test configurations and then the evaluated correlations are used to predict the modeling approximation errors in design configuration. Formulae to estimate the modeling approximation error using the correlations are derived based on the minimum variance approach and the physical interpretation of the formulae is discussed through simple cases. The proposed method is applied in 2 × 2 and 3 × 3 fuel assembly geometries using specifications of the KAIST benchmark problem. The correlation between the modeling approximation error and parameters (neutron leakage in each fuel assembly) is estimated in 2 × 2 fuel assemblies and then the modeling approximation error in 3 × 3 fuel assemblies is predicted using the correlation. The calculation results not only indicate feasibility of the present method, but also suggest a need for further investigation on the assumptions used in the present study, i.e. applicability and robustness of the correlation among different geometries.

DOI： 10.1080/00223131.2017.1286271

Web of Science

Scopus

Automated generation of burnup chain for reactor analysis applications

Tran, VP; Tran, HN; Yamamoto, A; Endo, T

KERNTECHNIK 82 巻 ( 2 ) 頁： 196 - 205 2017年4月

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

This paper presents the development of an automated generation of burnup chain for reactor analysis applications. Algorithms are proposed to reevaluate decay modes, branching ratios and effective fission product (FP) cumulative yields of a given list of important FPs taking into account intermediate reactions. A new burnup chain is generated using the updated data sources taken from the JENDL FP decay data file 2011 and Fission yields data file 2011. The new burnup chain is output according to the format for the SRAC code system. Verification has been performed to evaluate the accuracy of the new burnup chain. The results show that the new burnup chain reproduces well the results of a reference one with 193 fission products used in SRAC. Burnup calculations using the new burnup chain have also been performed based on UO2 and MOX fuel pin cells and compared with a reference chain th2cm6fp193bp6T.

DOI： 10.3139/124.110671

Web of Science

Scopus

Estimation of Modeling Approximation Errors using Data Assimilation with the Minimum Variance Approach 査読有り

A. Yamamoto,K. Kinoshita,T. Endo

J. Nucl. Sci. Technol. 54 巻頁： 459-471 2017年2月

GENESIS - A Three-dimensional Heterogeneous Transport Solver based on the Legendre Polynomial Expansion of Angular Flux Method 査読有り

A. Yamamoto,A. Giho,Y. Kato,T. Endo

Nucl. Sci. Eng. 186 巻頁： 1-22 2017年

Application of the GENESIS Code to the Kobayashi 3D Benchmark Problem 査読有り

Akio Yamamoto,Akinori Giho,Tomohiro Endo

Trans. Am. Nucl. Soc. 117 巻頁： 1403-1406 2017年

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