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Title: Subplane collision probabilities method applied to control rod cusping in 2D/1D

Abstract

The MPACT code is being jointly developed by the University of Michigan and Oak Ridge National Laboratory. It uses the 2D/1D method to solve neutron transport problems for reactors. The 2D/1D method decomposes the problem into a stack of 2D planes, and uses a high fidelity transport method to resolve all heterogeneity in each plane. These planes are then coupled axially using a lower order solver. Using this scheme, 3D solutions to the transport equation can be obtained at a much lower cost.One assumption made by the 2D/1D method is that the materials are axially homogeneous for each 2D plane. Violation of this assumption requires homogenization, which can significantly reduce the accuracy of the calculation. This paper presents two new subgrid methods to address this issue. The first method is polynomial decusping, a simple correction used to address control rods partially inserted into a 2D plane. The second is the subplane collision probabilities method, which is a more accurate, more robust subgrid method that can be applied to other axial heterogeneities.Each method was applied to a variety of problems. Results were compared to fine mesh solutions which had no axial heterogeneity and to Monte Carlo reference solutions generated using KENO-VI.more » It was shown that the polynomial decusping method was effective in many cases, but it had some limitations, with 3D pin power errors as high as 25% compared to KENO-VI. In conclusion, the subplane collision probabilities method performed much better, lowering the maximum pin power error to less than 5% in every calculation.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of Michigan, Ann Arbor, MI (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1439953
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Annals of Nuclear Energy (Oxford)
Additional Journal Information:
Journal Name: Annals of Nuclear Energy (Oxford); Journal Volume: 118; Journal Issue: C; Journal ID: ISSN 0306-4549
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; 2D/1D; Rod cusping; Subgrid methods

Citation Formats

Graham, Aaron M., Collins, Benjamin S., Stimpson, Shane G., and Downar, Thomas J.. Subplane collision probabilities method applied to control rod cusping in 2D/1D. United States: N. p., 2018. Web. doi:10.1016/j.anucene.2018.03.033.
Graham, Aaron M., Collins, Benjamin S., Stimpson, Shane G., & Downar, Thomas J.. Subplane collision probabilities method applied to control rod cusping in 2D/1D. United States. doi:10.1016/j.anucene.2018.03.033.
Graham, Aaron M., Collins, Benjamin S., Stimpson, Shane G., and Downar, Thomas J.. Fri . "Subplane collision probabilities method applied to control rod cusping in 2D/1D". United States. doi:10.1016/j.anucene.2018.03.033.
@article{osti_1439953,
title = {Subplane collision probabilities method applied to control rod cusping in 2D/1D},
author = {Graham, Aaron M. and Collins, Benjamin S. and Stimpson, Shane G. and Downar, Thomas J.},
abstractNote = {The MPACT code is being jointly developed by the University of Michigan and Oak Ridge National Laboratory. It uses the 2D/1D method to solve neutron transport problems for reactors. The 2D/1D method decomposes the problem into a stack of 2D planes, and uses a high fidelity transport method to resolve all heterogeneity in each plane. These planes are then coupled axially using a lower order solver. Using this scheme, 3D solutions to the transport equation can be obtained at a much lower cost.One assumption made by the 2D/1D method is that the materials are axially homogeneous for each 2D plane. Violation of this assumption requires homogenization, which can significantly reduce the accuracy of the calculation. This paper presents two new subgrid methods to address this issue. The first method is polynomial decusping, a simple correction used to address control rods partially inserted into a 2D plane. The second is the subplane collision probabilities method, which is a more accurate, more robust subgrid method that can be applied to other axial heterogeneities.Each method was applied to a variety of problems. Results were compared to fine mesh solutions which had no axial heterogeneity and to Monte Carlo reference solutions generated using KENO-VI. It was shown that the polynomial decusping method was effective in many cases, but it had some limitations, with 3D pin power errors as high as 25% compared to KENO-VI. In conclusion, the subplane collision probabilities method performed much better, lowering the maximum pin power error to less than 5% in every calculation.},
doi = {10.1016/j.anucene.2018.03.033},
journal = {Annals of Nuclear Energy (Oxford)},
number = C,
volume = 118,
place = {United States},
year = {Fri Apr 06 00:00:00 EDT 2018},
month = {Fri Apr 06 00:00:00 EDT 2018}
}

Journal Article:
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