Development of a Newtron-Krylov Iterative Method to Address Strong Non-Linear Feedback Effect in BWR Core Simulators
- North Carolina State University
A Newton-BICGSTAB solver has been developed to reduce the CPU execution time of BWR core simulators. The new solver treats the strong non-linearities in the problem explicitly using the Newton's method, replacing the traditionally used nested iterative approach. The Newton's method provides the solver with a higher-than-linear convergence rate, assuming that a good initial estimate of the unknowns is provided. Within each Newton iteration, an appropriately preconditioned BICGSTAB method is utilized for solving the linearized system of equations. Taking advantage of the higher convergence rate provided by the Newton's method and utilizing an efficient preconditioned BICGSTAB solver, we have developed a computationally efficient Newton-BICGSTAB solver to evaluate the three-dimensional, two-group neutron diffusion equations coupled with a two-phase flow model within a BWR core simulator. The robustness of the solver has been tested against numerous BWR core configurations and consistent results have been observed each time. The Newton-BICGSTAB solver provides an overall speedup of around 1.7 to the core simulator, with reference to the traditional approach. Isolating the solver portion of the core simulator, one can see that the new algorithm actually provides a speedup of around 1.9, of which 48% can be attributed to the BICGSTAB solver and the remaining 52% to Newton's method.
- Research Organization:
- Electric Power Research Center/Department of Nuclear Engineering
- DOE Contract Number:
- FG07-99ID13773
- OSTI ID:
- 804735
- Report Number(s):
- DOE/ID/13773
- Country of Publication:
- United States
- Language:
- English
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