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Title: Hybrid super homogenization and discontinuity factor method for continuous finite element diffusion

Abstract

This paper presents a novel homogenization equivalence technique aiming to simultaneously leveragethe simplicity of the Super Homogenization (SPH) method to reproduce reference reaction rates andthe ability to preserve reference leakage rates at desired surfaces through Discontinuity Factors (DF).The need for this new class of methods arises from the inability of the current state-of-the-art SPH technology to properly reproduce the reactor multiplication factor for problems with significant leakage. This work shows that this defect lies in the use of normalization factors in the SPH algorithm: while they are necessary with purely reflecting problems to ensure uniqueness of the solution, they introduce homogenization inconsistencies if at least one vacuum boundary condition is present. Two solutions to this problem are presented in this work: (i) to simply remove the normalization factor or (ii) to introduce additional degrees of freedom in the form of DFs in such a way that the normalization factors can still constrain the problem. While the former clearly offers unrivaled simplicity and can lead to very satisfactory results for leakage-dominated cores or if spatial restriction of the SPH regions is applied – as demonstrated for the High Temperature Test Reactor, the latter is more robust and does not require tomore » scale the fission terms with the reference eigenvalue.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Idaho National Lab. (INL), Idaho Falls, ID (United States)
Publication Date:
Research Org.:
Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1498269
Report Number(s):
INL/JOU-18-51060-Rev000
Journal ID: ISSN 0306-4549
Grant/Contract Number:  
AC07-05ID14517
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Annals of Nuclear Energy (Oxford)
Additional Journal Information:
Journal Volume: 128; Journal Issue: C; Journal ID: ISSN 0306-4549
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
97 MATHEMATICS AND COMPUTING; 22 GENERAL STUDIES OF NUCLEAR REACTORS; Finite Element Method; Super Homogenization (SPH); Discontinuity Factors; Rattlesnake Transport Code; Multiphysics Object Oriented Simulation Environment (MOOSE); High Temperature Test Reactor (HTTR)

Citation Formats

Labouré, Vincent, Wang, Yaqi, Ortensi, Javier, Schunert, Sebastian, Gleicher, Frederick, DeHart, Mark, and Martineau, Richard. Hybrid super homogenization and discontinuity factor method for continuous finite element diffusion. United States: N. p., 2019. Web. doi:10.1016/j.anucene.2019.01.003.
Labouré, Vincent, Wang, Yaqi, Ortensi, Javier, Schunert, Sebastian, Gleicher, Frederick, DeHart, Mark, & Martineau, Richard. Hybrid super homogenization and discontinuity factor method for continuous finite element diffusion. United States. https://doi.org/10.1016/j.anucene.2019.01.003
Labouré, Vincent, Wang, Yaqi, Ortensi, Javier, Schunert, Sebastian, Gleicher, Frederick, DeHart, Mark, and Martineau, Richard. 2019. "Hybrid super homogenization and discontinuity factor method for continuous finite element diffusion". United States. https://doi.org/10.1016/j.anucene.2019.01.003. https://www.osti.gov/servlets/purl/1498269.
@article{osti_1498269,
title = {Hybrid super homogenization and discontinuity factor method for continuous finite element diffusion},
author = {Labouré, Vincent and Wang, Yaqi and Ortensi, Javier and Schunert, Sebastian and Gleicher, Frederick and DeHart, Mark and Martineau, Richard},
abstractNote = {This paper presents a novel homogenization equivalence technique aiming to simultaneously leveragethe simplicity of the Super Homogenization (SPH) method to reproduce reference reaction rates andthe ability to preserve reference leakage rates at desired surfaces through Discontinuity Factors (DF).The need for this new class of methods arises from the inability of the current state-of-the-art SPH technology to properly reproduce the reactor multiplication factor for problems with significant leakage. This work shows that this defect lies in the use of normalization factors in the SPH algorithm: while they are necessary with purely reflecting problems to ensure uniqueness of the solution, they introduce homogenization inconsistencies if at least one vacuum boundary condition is present. Two solutions to this problem are presented in this work: (i) to simply remove the normalization factor or (ii) to introduce additional degrees of freedom in the form of DFs in such a way that the normalization factors can still constrain the problem. While the former clearly offers unrivaled simplicity and can lead to very satisfactory results for leakage-dominated cores or if spatial restriction of the SPH regions is applied – as demonstrated for the High Temperature Test Reactor, the latter is more robust and does not require to scale the fission terms with the reference eigenvalue.},
doi = {10.1016/j.anucene.2019.01.003},
url = {https://www.osti.gov/biblio/1498269}, journal = {Annals of Nuclear Energy (Oxford)},
issn = {0306-4549},
number = C,
volume = 128,
place = {United States},
year = {Fri Feb 01 00:00:00 EST 2019},
month = {Fri Feb 01 00:00:00 EST 2019}
}

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Cited by: 8 works
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Figures / Tables:

Figure 1 Figure 1: Number of linear iterations to reach convergence in the PJFNK solve as a function of the diffusion coefficient $$D$$ref for SPH with and without normalization factors, and for SPHDF. The dotted line represents the reference outgoing leakage rate out of the right boundary. When the SPH without normalizationmore » factor does not converge, the value is arbitrarily set to 1012 (any converged case requires less than 50 iterations and thus all appear with the scale chosen).« less

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