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Fujimura, Toichiro*; Okumura, Keisuke
JAERI-Research 2002-024, 27 Pages, 2002/11
JAERI-Research-2002-024.pdf:1.04MB
A prototype version of a diffusion code has been developed to analyze the hexagonal core as reduced moderation reactor and the applicability of some acceleration methods have been investigated to accelerate the convergence of the iterative solution method. The hexagonal core is divided into regular triangular prisms in the three-dimensional code MOSRA-Prism and a polynomial expansion nodal method is applied to approximate the neutron flux distribution by a cubic polynomial. The multi-group diffusion equation is solved iteratively with ordinal inner and outer iterations and the effectiveness of acceleration methods is ascertained by applying an adaptive acceleration method and a neutron source extrapolation method, respectively. The formulation of the polynomial expansion nodal method is outlined in the report and the local and global effectiveness of the acceleration methods is discussed with various sample calculations. A new general expression of vacuum boundary condition, derived in the formulation is also described.
Kuroishi, Takeshi; Nomura, Yasushi
Proceedings of International Conference on the New Frontiers of Nuclear Technology; Reactor Physics, Safety and High-Performance Computing (PHYSOR 2002) (CD-ROM), 10 Pages, 2002/10
To accelerate the slow convergence of the fission source distribution, the matrix k calculation has been developed and incorporated in the ordinary Monte Carlo method. The acceleration can be performed by the fission source correction using the eigenvector of the fission matrix, if the coupling coefficients are approximately evaluated in the middle of Monte Carlo calculation. In this paper, we propose two effective applications of the matrix k, that is, the acceleration repetition method and the source generation method. The former simply repeats the matrix k calculation, and the result for the irradiated fuel pin cell shows enough effective to accelerate the fission source on the criticality estimation. However, in some cases of the loosely coupled multi unit system, the repetition of matrix k more than twice could not be carried out to get into convergence because of many units of low source level. The latter is newly devised here to apply to such cases. The checkerboard fuel storage rack is one of the typical cases, and the calculated results show the effectiveness of this method.
Fujimura, Toichiro
JAERI-Data/Code 95-019, 54 Pages, 1996/01
JAERI-Data-Code-95-019.pdf:1.47MB
no abstracts in English
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JAERI-M 83-144, 40 Pages, 1983/09
no abstracts in English
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Nuclear Science and Engineering, 77, p.360 - 367, 1981/00
Times Cited Count：2 Percentile：45.38(Nuclear Science & Technology)no abstracts in English
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Nuclear Science and Engineering, 59(4), p.326 - 336, 1976/04
Times Cited Count：3no abstracts in English
