Effective triangular coarse-mesh scheme for hexagonal geometry diffusion calculations

Journal Article · Sat Dec 31 04:00:00 EST 1994 · Transactions of the American Nuclear Society

OSTI ID:89277

Coppa, G G.M.; Ravetto, P; Bovio, L; Cassina, G

The basis of a multidimensional reactor dynamics code is an efficient algorithm to solve the stationary diffusion equation. When a small number of large space meshes are employed, algorithms more sophisticated than finite differences are necessary. In this paper a discretization procedure suitable for treating diffusion problems in hexagonal geometry using a triangular grid is presented. The technique associates simplicity and speed with effectiveness and accuracy. The leading principles of the method are as follows: (1) A solution of the diffusion equation within each spatial mesh is used to calculate parameters that relate edge currents and fluxes with mesh average flux and source; these response coefficients are employed to write an algebraic system for the average flux; every equation involves the flux of a triangle and those of the three nearest meshes. (2) In each mesh the multigroup equations are uncoupled by a diagonalization procedure; in such a way, the shape of the slowing-down source for each group is described exactly. In a previous work, the technique was applied directly to hexagonal meshes. However, the use of triangular meshes is preferred as it allows one to refine the grid indefinitely.

• OSTI ID: 89277
• Report Number(s): CONF-941102--
• Journal Information: Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 71; ISSN 0003-018X; ISSN TANSAO
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
ALGORITHMS
CALCULATION METHODS
HEXAGONAL CONFIGURATION
NEUTRON DIFFUSION EQUATION
NEUTRON FLUX
REACTOR CORES