A transient, quadratic nodal method for triangular-Z geometry
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Many systematically-derived nodal methods have been developed for Cartesian geometry due to the extensive interest in Light Water Reactors. These methods typically model the transverse-integrated flux as either an analytic or low order polynomial function of position within the node. Recently, quadratic nodal methods have been developed for R-Z and hexagonal geometry. A static and transient quadratic nodal method is developed for triangular-Z geometry. This development is particularly challenging because the quadratic expansion in each node must be performed between the node faces and the triangular points. As a consequence, in the 2-D plane, the flux and current at the points of the triangles must be treated. Quadratic nodal equations are solved using a non-linear iteration scheme, which utilizes the corrected, mesh-centered finite difference equations, and forces these equations to match the quadratic equations by computing discontinuity factors during the solution. Transient nodal equations are solved using the improved quasi-static method, which has been shown to be a very efficient solution method for transient problems. Several static problems are used to compare the quadratic nodal method to the Coarse Mesh Finite Difference (CMFD) method. The quadratic method is shown to give more accurate node-averaged fluxes. However, it appears that the method has difficulty predicting node leakages near reactor boundaries and severe material interfaces. The consequence is that the eigenvalue may be poorly predicted for certain reactor configurations. The transient methods are tested using a simple analytic test problem, a heterogeneous heavy water reactor benchmark problem, and three thermal hydraulic test problems. Results indicate that the transient methods have been implemented correctly.
- Research Organization:
- Oak Ridge Associated Universities, Inc., TN (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76OR00033
- OSTI ID:
- 10102858
- Report Number(s):
- DOE/OR/00033-T570; ON: DE94001413
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: Jun 1993
- Country of Publication:
- United States
- Language:
- English
Similar Records
Status of the Development of an Embedded Transport Treatment of Control Rods and of Radial Flux Expansion in Cylindrical Nodal Diffusion Codes
Coupled Neutron and Gamma Heating Calculation Based on VARIANT Nodal Transport Method