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Wire wrapped fuel pin hexagonal arrays for PWR service

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dc.contributor.advisor Neil E. Todreas. en_US Diller, Peter Ray en_US
dc.contributor.other Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering. en_US 2008-09-03T14:47:00Z 2008-09-03T14:47:00Z 2005 en_US 2005 en_US
dc.description Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2005. en_US
dc.description Includes bibliographical references (p. 231-234). en_US
dc.description.abstract This work contributes to the Hydride Fuels Project, a collaborative effort between UC Berkeley and MIT aimed at investigating the potential benefits of hydride fuel use in light water reactors (LWRs). Core design is accomplished for both hydride and oxide-fueled cores over a range of geometries via steady-state and transient thermal hydraulic analyses, which yield the maximum power, and fuel performance and neutronics studies, which provide the achievable discharge burnup. The final optimization integrates the outputs from these separate studies into an economics model to identify geometries offering the lowest cost of electricity, and provide a fair basis for comparing the performance of hydride and oxide fuels. This work focuses on the steady-state and transient thermal hydraulic as well as economic analyses for PWR cores utilizing wire wraps in a hexagonal array with UZrH1.6 and UO2. It was previously verified that square and hexagonal arrays with matching rod diameters and H/HM ratio have the same thermal hydraulic performance. In this work, this equivalence is extended to hexagonal wire wrap arrays, and verified by comparing the thermal hydraulic performance of a single hexagonal wire wrap core with its equivalent square array core with grid spacers. A separate neutronics equivalence is developed, based on the assumption that arrays with matching rod diameters and H/HM ratios will have identical neutronic performance. Steady-state design limits were separated into hard limits, which must be satisfied, or soft limits, which serve to keep the design reasonable. Design limits were placed on the pressure drop, critical heat flux (CHF), vibrations, and fuel and cladding temperature. Vibrations limits on the wire wrap assemblies were imposed for flow induced vibrations (FIV) and thermal hydraulic vibrations (THV). en_US
dc.description.abstract (cont.) An analysis of the fretting wear of wire wraps was performed, which outperformed the analogous fretting wear analysis for grid spacers. A CHF study found wire wraps to outperform grid spacers. LOCA and overpower transient analyses were performed for wire wraps. The overpower transient was analyzed over a range of geometries, and found to be more limiting than the steady-state analysis. The LOCA was analyzed for various powers at the reference geometry and another geometry of interest. Through all of these analyses, it was determined that the thermal hydraulic performance of UZrH1 .6 and UO2 are very similar. The optimal wire wrap designs were found to have significantly higher maximum powers than the reference core, allowing for uprates up to -54%. This is due to improved vibrations, pressure drop, and CHF. The steady-state and transient analyses were combined with fuel performance and neutronic studies into an economics model that determines the optimal geometries for incorporation into existing PWR's. The model also provides a basis for comparing the performance of UZrH1.6 to UO2 for a range of core geometries. Results presented herein show cost savings for oxide fuel with wire wraps over grid spacers of at least 0.8 mils/kWe-hr, or 4%, due to power increases predicted by the thermal hydraulic analyses. Wire wrap UZrHI.6 has a COE savings over U02 of 0.7 mils/kWe-hr, or 4%. Due to the large power uprates possible, a utility could achieve a cost savings of up to 10.9 mils/kWe-hr, or 40%, with a UZrH1.6 wire wrap uprate instead of building a new core. en_US
dc.description.statementofresponsibility by Peter Ray Diller. en_US
dc.format.extent 258 p. en_US
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights 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. en_US
dc.rights.uri en_US
dc.subject Nuclear Science and Engineering. en_US
dc.title Wire wrapped fuel pin hexagonal arrays for PWR service en_US
dc.type Thesis en_US S.M. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering. en_US
dc.identifier.oclc 228842111 en_US

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