Buckled spherical harmonics solutions of neutron transport problems
The within-group even-parity transport equation is formulated with complex angular and spatial trial functions and with a complex buckling approximation. Three angular trial functions are compared: finite elements, discrete ordinates, and complex spherical harmonics. When discrete ordinates or finite element basis functions are applied, the differential equations for the real and imaginary parts of the even-parity flux are coupled by the buckling vector. The spherical harmonics equations for the real and imaginary parts of the even-party flux, however, uncouple when one particular transverse buckling direction is chosen for a two-dimensional problem. Bilinear rectangular finite elements are applied to the spatial variable, the buckled spherical harmonics angular treatment is generalized to arbitrary order, and the resulting formulation is incorporated into a multigroup formalism by use of a lumped source approximation. The finite element/buckled spherical harmonics multigroup neutron transport code FESH was developed from these approximations; the code treats either fixed-source problems or criticality eigenvalue problems. The applicability of this method to problems with several thousand spatial nodes was demonstrated by comparison of numerical results with another spherical harmonics code and with other computational methods. Buckled two-dimensional eigenvalue calculations reveal substantial improvements over the DB/sup 2/ buckling method when transverse transport effects are important.
- Research Organization:
- Northwestern Univ., Evanston, IL (USA)
- OSTI ID:
- 5455009
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BUCKLING
COMPUTER CALCULATIONS
EIGENVALUES
EVALUATION
FINITE ELEMENT METHOD
MULTIGROUP THEORY
NEUTRON TRANSPORT THEORY
NUMERICAL SOLUTION
SPHERICAL HARMONICS METHOD
TRANSPORT THEORY
TWO-DIMENSIONAL CALCULATIONS