Three-dimensional nodal homogenization technique using a finite element method

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

OSTI ID:89127

Sutton, T M; Kudlacik, T B

In recent years, advanced nodal methods for diffusion theory analysis have been developed that permit accurate coarse-mesh three-dimensional calculations to be performed routinely. At the same time, computer capabilities have advanced rapidly so that explicit fine-mesh three-dimensional diffusion theory calculations are also routine, though much more expensive. We have developed and implemented methods for linking nodal and fine-mesh three-dimensional calculations. The combined system provides improved homogenization for nodal parametric studies and potential for greatly reducing the time for fine-mesh calculations involving temperature feedback and criticality searches. In this paper we describe a technique for obtaining nodal parameters from the results of a three-dimensional fine-mesh finite element/finite difference calculation. For axially uniform models, this method reduces to that used in our two-dimensional finite element homogenization procedures In two dimensions, the homogenization is exact - i.e., a nodal calculation reproduces the fine-mesh solution exactly. In three-dimensional calculations, we do not homogenize in the axial direction, and hence we do not compute or use axial discontinuity factors. Because of this, the nodal solution will not match the fine-mesh solution precisely, but the differences are negligible for problems of practical interest.

• OSTI ID: 89127
• 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
66 PHYSICS
FINITE DIFFERENCE METHOD
FINITE ELEMENT METHOD
HOMOGENIZATION METHODS
MODIFICATIONS
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NODAL EXPANSION METHOD
THREE-DIMENSIONAL CALCULATIONS