Modeling of boundary conditions in embedded lattice calculations

Examensarbete för masterexamen

Please use this identifier to cite or link to this item: https://hdl.handle.net/20.500.12380/212132
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Type: Examensarbete för masterexamen
Master Thesis
Title: Modeling of boundary conditions in embedded lattice calculations
Authors: Martin, Daniel
Abstract: The coupling of the fine-mesh high-order transport operator with a coarse-mesh low-order approximation, in order to reduce the computational requirements when simulating whole reactor cores, is studied here through the boundary conditions for the fine-mesh solver. A recently developed software, solving the neutron transport equation though a discontinuous Galerkin Finite Element discrete-ordinates method, is used for the fine-mesh high-order solver, and the coarse-mesh low-order solver is simulated by a coarsening process. As a first step, a verification and validation process is necessary to be performed. This is carried out using the softwares DRAGON and MCNP, respectively, as the references in the verification and validation processes. A very good agreement is obtained during the verification process, while for the validation, results show that different quadratures should be considered in order to improve the accuracy. In addition, a parametric study is presented, where the different parameters of the spatial and angular discretizations are analyzed, in order to understand the behavior of the solver for different configurations. A second part of the work consists in studying the effect of coarsening the boundary conditions for a particular problem (C5G7 benchmark). This coarsening is performed to simulate the low-order approximation of the boundary conditions obtained with the coarse-mesh solver. Understanding the loss of accuracy for the fine-mesh calculations is necessary in order to improve the fine-mesh/coarse-mesh coupling for the neutronic solvers.
Keywords: Beräkningsfysik;Energi;Teknisk fysik;Computational physics;Energy;Engineering physics
Issue Date: 2015
Publisher: Chalmers tekniska högskola / Institutionen för teknisk fysik
Chalmers University of Technology / Department of Applied Physics
Series/Report no.: CTH-NT - Chalmers University of Technology, Nuclear Engineering : 307
URI: https://hdl.handle.net/20.500.12380/212132
Collection:Examensarbeten för masterexamen // Master Theses



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