{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/46658"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/46658","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Tightly coupled neutronics and thermal-hydraulics using open-source software","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.","abstract_html":"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.","abstract_has_math":false,"creators":["Wu, Hsingtzu"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Nuclear Engineering","degree_department":null,"school":null,"contributors":["Uddin, Rizwan","Jewett, Brian F.","Kozlowski, Tomasz","Stubbins, James F."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-01-16T17:57:56Z","date_published":"2014-01-16T17:57:56Z","updated_at":"2026-07-22T22:25:36Z","subjects":["coupling neutronics","tight coupling","thermal-hydraulics"],"languages":["en"],"rights":["Copyright 2013 Hsingtzu Wu"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/46658","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Uddin, Rizwan","Jewett, Brian F.","Kozlowski, Tomasz","Stubbins, James F."]},{"key":"dc:creator","label":"Author","values":["Wu, Hsingtzu"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2014-01-16T17:57:56Z","2013-12"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Nuclear Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["coupling neutronics","tight coupling","thermal-hydraulics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2013 Hsingtzu Wu"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/46658"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["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.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2013-09-19T13:54:40Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Wu_Hsingtzu.pdf: 2836071 bytes, checksum: 176e24282ebd4b78eace7d113c6c250c (MD5)","Made available in DSpace on 2014-01-16T17:57:56Z (GMT). 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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.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2013-09-19T13:54:40Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Wu_Hsingtzu.pdf: 2836071 bytes, checksum: 176e24282ebd4b78eace7d113c6c250c (MD5)","Made available in DSpace on 2014-01-16T17:57:56Z (GMT). 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