JOPSS - Search Results

Journal Articles

Sensitivity coefficient evaluation of an accelerator-driven system using ROM-Lasso method

Katano, Ryota; Yamamoto, Akio*; Endo, Tomohiro*

Nuclear Science and Engineering, 196(10), p.1194 - 1208, 2022/10

https://doi.org/10.1080/00295639.2022.2067447

Times Cited Count：1 Percentile：31.61(Nuclear Science & Technology)

In this study, we propose the ROM-Lasso method that enables efficient evaluation of sensitivity coefficients of neutronics parameters to cross-sections. In the proposed method, a vector of sensitivity coefficients is expanded by subspace bases, so-called Active Subspace (AS) based on the idea of Reduced Order Modeling (ROM). Then, the expansion coefficients are evaluated by the Lasso linear regression between cross-sections and neutronics parameters obtained by the random sampling. The proposed method can be applied in the case where the adjoint method is difficult to be applied since the proposed method uses only forward calculations. In addition, AS is an effective subspace that can expand the vector of sensitivity coefficients with the lower number of dimension. Thus, the number of unknows is reduced from the original number of input parameters and the calculation cost is dramatically improved compared to the Lasso regression without AS. In this paper, we conducted ADS burnup calculations as a verification. We have shown how AS bases are obtained and the applicability of the proposed method.

JAEA Reports

New method for model coupling using Stampi; Application to the coupling of Atmosphere Model (MM5) and Land-Surface Model (SOLVEG)

Nagai, Haruyasu

JAERI-Data/Code 2003-021, 36 Pages, 2003/12

JAERI-Data-Code-2003-021.pdf:1.73MB

A new method to couple atmosphere and land-surface models using the massage passing interface (MPI) was proposed to develop a atmosphere-land model for studies on heat, water, and material exchanges at around the land surface. A non-hydrostatic atmospheric dynamic model of Pennsylvania State University and National Center for Atmospheric Research (PUS/NCAR-MM5) and a detailed land surface model (SOLVEG) including the surface-layer atmosphere, soil, and vegetation developed at Japan Atomic Energy Research Institute (JAERI) are used as the atmosphere and land-surface models, respectively. Concerning the MPI, a message passing library named Stampi developed at JAERI that can be used between different parallel computers is used. The models are coupled by exchanging calculation results by using MPI on their independent parallel calculations.

JAEA Reports

Program CCOM; Coupled-channels optical model calculation with automatic parameter search

Iwamoto, Osamu

JAERI-Data/Code 2003-020, 22 Pages, 2003/12

JAERI-Data-Code-2003-020.pdf:0.98MB

A new program of coupled-channels optical model calculation has been developed for the evaluation of actinide nuclei. The code is composed of by the modules having high independency and large flexibility. The code is written by C++ language using object oriented techniques. The program has capability of fitting of the parameters even for the several nuclei at the same time. The formulae required in the calculation, details of the numerical treatments and the input parameters are described. The examples of the input file and the output are also shown.

Journal Articles

Coupled-channels analysis of nucleon interaction data of $^{28,30}$ Si up to 200 MeV based on the soft rotator model

Sun, W.*; Watanabe, Yukinobu*; Sukhovitskij, E.*; Iwamoto, Osamu; Chiba, Satoshi

Journal of Nuclear Science and Technology, 40(9), p.635 - 643, 2003/09

https://doi.org/10.3327/jnst.40.635

Times Cited Count：10 Percentile：56.43(Nuclear Science & Technology)

A consistent analysis for nuclear level structure and nucleon scattering data up to 200 MeV were performed for sd-shell nuclei, $^{28,30}$ Si, using a unified framework of soft-rotator model and coupled-channels approach. The soft-rotator model parameters and optical model parameters were derived. The calculations showed good agreement with experimental data for both collective level and nucleon interaction data -- neutron total cross sections, proton reaction cross sections, and nucleon scattering angular distributions.

Journal Articles

Evaluation of neutron nuclear data for sodium-23

Shibata, Keiichi

Journal of Nuclear Science and Technology, 39(10), p.1065 - 1071, 2002/10

https://doi.org/10.3327/jnst.39.1065

Times Cited Count：6 Percentile：39.54(Nuclear Science & Technology)

Neutron nuclear data of $^{23}$ Na have been evaluated in the neutron energy region up to 20 MeV. Evaluated are the elastic and inelastic scattering, capture, (n,2n), (n,p), (n,), (n,np), (n,n) reaction and -ray production cross sections, and the angular and energy distributions of neutrons and -rays. The evaluation is mainly based on nuclear model calculations. The pre-equilibrium and direct-reaction processes were taken into account in addition to the compound process. The evaluated data have been compiled into the latest version of JENDL, JENDL-3.3.

JAEA Reports

Evaluation of neutron-induced reactions on $^{236}$ Pu for JENDL-3.3

Iwamoto, Osamu; Nakagawa, Tsuneo

JAERI-Research 2002-013, 18 Pages, 2002/07

JAERI-Research-2002-013.pdf:0.7MB

Cross sections and energy-angular distributions of emitted neutrons were evaluated for the neutron-incident reactions on $^{236}$ Pu in the incident energy range of 10eV to 20MeV by using a statistical model combined with a coupled channel optical model. The calculated results were compiled to the latest evaluated nuclear data library JENDL-3.3 in the ENDF-6 format. The unresolved resonance region is assumed to be from 10eV to 30keV, and the averaged resonance parameters were obtained to reproduce the calculated cross sections. Maxwell temperatures for fission neutron spectra were estimated from a systematics with a correction for prefission neutrons.

JAEA Reports