Tightly coupled neutronics and thermal-hydraulics using open-source software

Wu, Hsingtzu

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https://hdl.handle.net/2142/46658 Copy

Description

Title

Tightly coupled neutronics and thermal-hydraulics using open-source software

Author(s)

Wu, Hsingtzu

Issue Date

2014-01-16T17:57:56Z

Director of Research (if dissertation) or Advisor (if thesis)

Uddin, Rizwan

Doctoral Committee Chair(s)

Uddin, Rizwan

Committee Member(s)

• Jewett, Brian F.
• Kozlowski, Tomasz
• Stubbins, James F.

Department of Study

Nuclear, Plasma, & Rad Engr

Discipline

Nuclear Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(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.

Graduation Semester

2013-12

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http://hdl.handle.net/2142/46658

Copyright and License Information

Copyright 2013 Hsingtzu Wu

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