A nodal expansion method using conformal mapping for hexagonal geometry
- Westinghouse Electric Corp., Pittsburgh, PA (United States)
Hexagonal nodal methods adopting the same transverse integration process used for square nodal methods face the subtle theoretical problem that this process leads to highly singular nonphysical terms in the diffusion equation. Lawrence, in developing the DIF3D-N code, tried to approximate the singular terms with relatively simple polynomials. In the HEX-NOD code, Wagner ignored the singularities to simplify the diffusion equation and introduced compensating terms in the nodal equations to restore the nodal balance relation. More recently developed hexagonal nodal codes, such as HEXPE-DITE and the hexagonal version of PANTHER, used methods similar to Wagner's. It will be shown that for light water reactor applications, these two different approximations significantly degraded the accuracy of the respective method as compared to the established square nodal methods. Alternatively, the method of conformal mapping was suggested to map a hexagon to a rectangle, with the unique feature of leaving the diffusion operator invariant, thereby fundamentally resolving the problems associated with transverse integration. This method is now implemented in the Westinghouse hexagonal nodal code ANC-H. In this paper we report on the results of comparing the three methods for a variety of problems via benchmarking against the fine-mesh finite difference code.
- OSTI ID:
- 6959987
- Report Number(s):
- CONF-931160-; CODEN: TANSAO
- Journal Information:
- Transactions of the American Nuclear Society; (United States), Vol. 69; Conference: American Nuclear Society (ANS) winter meeting, San Francisco, CA (United States), 14-18 Nov 1993; ISSN 0003-018X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NEUTRON DIFFUSION EQUATION
ANALYTIC FUNCTIONS
NODAL EXPANSION METHOD
ACCURACY
BWR TYPE REACTORS
CONFORMAL MAPPING
D CODES
FINITE DIFFERENCE METHOD
H CODES
P CODES
PWR TYPE REACTORS
REACTOR KINETICS
CALCULATION METHODS
COMPUTER CODES
DIFFERENTIAL EQUATIONS
ENRICHED URANIUM REACTORS
EQUATIONS
FUNCTIONS
ITERATIVE METHODS
KINETICS
MAPPING
NUMERICAL SOLUTION
POWER REACTORS
REACTORS
THERMAL REACTORS
TOPOLOGICAL MAPPING
TRANSFORMATIONS
WATER COOLED REACTORS
WATER MODERATED REACTORS
210100* - Power Reactors
Nonbreeding
Light-Water Moderated
Boiling Water Cooled
210200 - Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled