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Title:Tightly coupled neutronics and thermal-hydraulics using open-source software
Author(s):Wu, Hsingtzu
Director of Research:Uddin, Rizwan
Doctoral Committee Chair(s):Uddin, Rizwan
Doctoral Committee Member(s):Jewett, Brian F.; Kozlowski, Tomasz; Stubbins, James F.
Department / Program:Nuclear, Plasma, & Rad Engr
Discipline:Nuclear Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):coupling neutronics
tight coupling
thermal-hydraulics
Abstract:Coupling the neutronic and thermal-hydraulic analyses of a nuclear reactor core is important because it helps identify the most relevant safety issues. Currently all coupled computations solve the same set of governing equations using different coupling methods, which can be sorted into two categories: loose coupling and tight coupling. This dissertation proposes and verifies a third coupled approach called “the Integrated Tight Coupling (ITC) method”. The mathematical equations in the nuclear fuel are rearranged to be integrated via a novel concept of group temperature. In addition, the data from the neutron cross section library can be used directly. The ITC method is implemented using two open-source codes: the DRAGON code and OpenFOAM. Additionally, a coupled computation using these two codes is new and has not been done in the past. The ITC method is verified using two 1.5-D (1-D neutronics and 2-D thermal-hydraulics) examples: a symmetric unit cell and an asymmetric unit cell. The mesh of the tightly integrated computation is 25 % and 12 % coarser than the loosely coupled one for the symmetric case and the asymmetric case, respectively. Starting from the similar initial guess, the number of iterations for the ITC method is 24 % and 14 % fewer than those for the loosely coupled computation to reach the same accuracy for the symmetric case and the asymmetric case, respectively. In addition, the ITC method is tested with different initial guesses. For all cases tested, the scheme converged to the same solution. With further improvement and additional testing, the scheme developed and tested here has the potential to be incorporated with other neutronics and thermal- hydraulics codes.
Issue Date:2014-01-16
URI:http://hdl.handle.net/2142/46658
Rights Information:Copyright 2013 Hsingtzu Wu
Date Available in IDEALS:2014-01-16
Date Deposited:2013-12


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