JOPSS - Search Results

Journal Articles

Estimation of change in $k_mathit{eff}$ due to perturbed fission-source distribution

Nagaya, Yasunobu; Mori, Takamasa; Brown, F. B.*

Monte Karuro Keisanho Kodoka No Genjo; Dai-3-Kai Monte Karuro Shimyureshon Kenkyukai Hobunshu, p.105 - 115, 2004/12

The Monte Carlo perturbation method based on the differential operator sampling method has been widely used to obtain a small change in neutronic parameters or sensitivity. The method is very effective for fixed-source problems but a difficulty arises for eigenvalue problems because the fission source distribution is perturbed. Most Monte Carlo codes assume that the source distribution is unchanged after a perturbation is introduced. However, this assumption can lead to a significant error in the perturbation estimate. Recently, a method to estimate the perturbed fission source effect has been proposed. In this method, the additional weights for the differential coefficient of the fission source at fission sites are normalized in each cycle, and the effect is estimated by propagating the normalized additional weight between cycles. The method and benchmark results have been reviewed. It has been found that this method is very effective in perturbation calculations for the effective multiplication factor.

Journal Articles

Reliable method for fission source convergence of Monte Carlo criticality calculation with Wielandt's method

Yamamoto, Toshihiro; Miyoshi, Yoshinori

Journal of Nuclear Science and Technology, 41(2), p.99 - 107, 2004/02

https://doi.org/10.3327/jnst.41.99

Times Cited Count：38 Percentile：90.02(Nuclear Science & Technology)

A new algorithm of Monte Carlo criticality calculations for implementing Wielandt's method is developed. In this algorithm, part of fission neutrons emitted during random walk processes are tracked within the same generation, and thus a fission source distribution in the next generation spread more widely. Applying this method intensifies a neutron interaction effect even in a loosely-coupled array where conventional Monte Carlo criticality calculation methods have difficulties, and a converged fission source distribution can be obtained with fewer generations. Computing time spent for one generation, however, increases because of tracking fission neutrons within the same generation, which eventually results in an increase of total computing time up to convergence. However, since a fission source convergence is attained with fewer source iterations, a reliable determination of convergence can easily be made even in a system with a slow convergence.

JAEA Reports

Subroutine library for error estimation of matrix computation, Ver.1.0

*; *; *

JAERI-Data/Code 99-016, 183 Pages, 1999/03

JAERI-Data-Code-99-016.pdf:4.87MB

no abstracts in English

JAEA Reports

Parallelization of mathematical library for generalized eigenvalue problem for real band matrices

JAERI-Data/Code 97-016, 34 Pages, 1997/05

JAERI-Data-Code-97-016.pdf:1.03MB

no abstracts in English

JAEA Reports

A User's manual of tools for error estimation of complex number matrix computation (Ver.1.0)

JAERI-Data/Code 97-011, 25 Pages, 1997/03

JAERI-Data-Code-97-011.pdf:0.8MB

no abstracts in English

Journal Articles

Development of parallel libraries

; *; *; *; *; *; *; Yokokawa, Mitsuo;

Joho Shori Gakkai Kenkyu Hokoku, 96(81), p.129 - 134, 1996/08

no abstracts in English

JAEA Reports

Numerical method for the eigenvalue problem and the singular equation by using the Multi-Grid Method and application to ordinary differential equation

*; Tokuda, Shinji; Uyama, Tadao*

JAERI-Research 95-050, 29 Pages, 1995/07

JAERI-Research-95-050.pdf:1.29MB

no abstracts in English

JAEA Reports

Dynamic analysis of liquid-filled shells

PNC TN9410 90-099, 73 Pages, 1990/06

PNC-TN9410-90-099.pdf:1.22MB

Fluid-structure interaction affects dynamic characteristics of LMFBR reactor structures, and should be taken into consideration in their seismic safety evalutions. This is due to that a reactor vessel of LMFBR is relatively thin-walled structure and it contains a large amount of liquid metal sodlum. In this study, natural frequencies of liquid-filled tanks (a flat bottom end plate type and a spherical head type) were analyzed by FINAS with a purpose of understanding the dynamic behavior of liquid-filled tanks. The analysis results by FINAS were found to be satisfactory accurate as compared to the exliting solutions. And a computational study was made on vibration characteristics of tanks and follwing knowledge was obtaind. (1)The lowest natural frequency of a shell takes place not in a beam mode, but in a higher order (5th10th) shell mode. (2)In case of a tank with a spherical head, elgenmode shapes are very complex; The spherical head part tends to vibrate mainly in the lower order shell modes, and the cylinderical part vibrate in the higher order modes. (3)The center of the spherical head becomes a nodal point in the beam modes and the shell modes. But in the axial modes, the center becomes a point of maximum amplitude.