CFD in support of development and optimization of the MIT LEU fuel element design

Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2014. === Cataloged from PDF version of thesis. === Includes bibliographical references (page 85). === The effect of lateral power distribution of the MITR LEU fuel design was analyzed using Computati...

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Main Author: Diaconeasa, Mihai Aurelian
Other Authors: Emilio Baglietto and Lin-wen Hu.
Format: Others
Language:English
Published: Massachusetts Institute of Technology 2015
Subjects:
Online Access:http://hdl.handle.net/1721.1/95601
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spelling ndltd-MIT-oai-dspace.mit.edu-1721.1-956012019-05-02T15:50:22Z CFD in support of development and optimization of the MIT LEU fuel element design Computational fluid dynamics in support of development and optimization of the Massachusetts Institute of Technology Research Reactor low-enriched uranium fuel element design Diaconeasa, Mihai Aurelian Emilio Baglietto and Lin-wen Hu. Massachusetts Institute of Technology. Department of Nuclear Science and Engineering. Massachusetts Institute of Technology. Department of Nuclear Science and Engineering. Nuclear Science and Engineering. Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2014. Cataloged from PDF version of thesis. Includes bibliographical references (page 85). The effect of lateral power distribution of the MITR LEU fuel design was analyzed using Computational Fluid Dynamics. Coupled conduction and convective heat transfer were modeled for uniform and non-uniform lateral power distributions. It was concluded that, due to conduction, the maximum heat flux ratio on the cladding surface is 1.16, compared to the maximum volumetric power generation ratio of 1.23. The maximum cladding temperature occurs roughly 0.5 inches from the edge of the support plate, while the peak volumetric power generation is located at the end of the fuel meat, about 0.1 inches from the edge of the support plate. Although the heat transfer coefficient is lower in the corner of the coolant channel, this has a negligible effect on the peak cladding temperature, i.e. the peak cladding temperature is related to heat flux only and a "channel average" heat transfer coefficient can be adopted. Moreover, coolant temperatures in the radial direction are reasonably uniform, which is indicative of good lateral mixing. Finally, a quasi-DNS study has been performed to analyze the effect of the fuel grooves on the local heat transfer coefficient. The quasi-DNS results bring useful insights, showing two main effects related to the existence of the grooves. First, the increased surface leads to an increase in the pressure drop and further, the flow aligned configuration of the grooves limits the ability of the near wall turbulent structures to create mixing, leading to a noticeable reduction in the local heat transfer coefficient at the base of the grooves. Overall, this leads to an effective decrease in the local heat transfer coefficient, but due to the increased heat transfer surface the global heat transfer is enhanced in comparison to the flat plate configuration. The improved understanding of the effects of grooves on the local heat transfer phenomena provides a useful contribution to future fuel design considerations. For example, the increase in pressure drop, together with the reduction in the local heat transfer coefficient indicated that the selection of a grooved wall channel instead of a smooth wall channel might not necessarily be optimal, particularly if fabrication issues are taken into account, together with the concern that grooved walls may promote oxide growth and crud formation during the life of the fuel. by Mihai Aurelian Diaconeasa. S.M. 2015-02-25T17:13:08Z 2015-02-25T17:13:08Z 2014 2014 Thesis http://hdl.handle.net/1721.1/95601 903705552 eng M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 96 pages application/pdf Massachusetts Institute of Technology
collection NDLTD
language English
format Others
sources NDLTD
topic Nuclear Science and Engineering.
spellingShingle Nuclear Science and Engineering.
Diaconeasa, Mihai Aurelian
CFD in support of development and optimization of the MIT LEU fuel element design
description Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2014. === Cataloged from PDF version of thesis. === Includes bibliographical references (page 85). === The effect of lateral power distribution of the MITR LEU fuel design was analyzed using Computational Fluid Dynamics. Coupled conduction and convective heat transfer were modeled for uniform and non-uniform lateral power distributions. It was concluded that, due to conduction, the maximum heat flux ratio on the cladding surface is 1.16, compared to the maximum volumetric power generation ratio of 1.23. The maximum cladding temperature occurs roughly 0.5 inches from the edge of the support plate, while the peak volumetric power generation is located at the end of the fuel meat, about 0.1 inches from the edge of the support plate. Although the heat transfer coefficient is lower in the corner of the coolant channel, this has a negligible effect on the peak cladding temperature, i.e. the peak cladding temperature is related to heat flux only and a "channel average" heat transfer coefficient can be adopted. Moreover, coolant temperatures in the radial direction are reasonably uniform, which is indicative of good lateral mixing. Finally, a quasi-DNS study has been performed to analyze the effect of the fuel grooves on the local heat transfer coefficient. The quasi-DNS results bring useful insights, showing two main effects related to the existence of the grooves. First, the increased surface leads to an increase in the pressure drop and further, the flow aligned configuration of the grooves limits the ability of the near wall turbulent structures to create mixing, leading to a noticeable reduction in the local heat transfer coefficient at the base of the grooves. Overall, this leads to an effective decrease in the local heat transfer coefficient, but due to the increased heat transfer surface the global heat transfer is enhanced in comparison to the flat plate configuration. The improved understanding of the effects of grooves on the local heat transfer phenomena provides a useful contribution to future fuel design considerations. For example, the increase in pressure drop, together with the reduction in the local heat transfer coefficient indicated that the selection of a grooved wall channel instead of a smooth wall channel might not necessarily be optimal, particularly if fabrication issues are taken into account, together with the concern that grooved walls may promote oxide growth and crud formation during the life of the fuel. === by Mihai Aurelian Diaconeasa. === S.M.
author2 Emilio Baglietto and Lin-wen Hu.
author_facet Emilio Baglietto and Lin-wen Hu.
Diaconeasa, Mihai Aurelian
author Diaconeasa, Mihai Aurelian
author_sort Diaconeasa, Mihai Aurelian
title CFD in support of development and optimization of the MIT LEU fuel element design
title_short CFD in support of development and optimization of the MIT LEU fuel element design
title_full CFD in support of development and optimization of the MIT LEU fuel element design
title_fullStr CFD in support of development and optimization of the MIT LEU fuel element design
title_full_unstemmed CFD in support of development and optimization of the MIT LEU fuel element design
title_sort cfd in support of development and optimization of the mit leu fuel element design
publisher Massachusetts Institute of Technology
publishDate 2015
url http://hdl.handle.net/1721.1/95601
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