Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 11 of 11 for “"Air Ingress"”.
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Zirconium alloy getter bed air-ingress thermal failure analysis
In the event of an unexpected inrush of air into a packed St-909 getter bed, the exothermic reaction of oxygen and pellet material pushes temperatures within the bed to extremely high levels. This failure mode, which could be caused by a line rupture, was modeled, analyzed, and a full-scale …
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CFD Analyses of Flow Structures in Air-Ingress and Rod Bundle Problems
… included in this dissertation. One study is the air-ingress phenomenon during a loss of coolant accident (LOCA) scenario, and the other is a 5-by-5 bundle assembly problem under a design of PWRs. The objectives are to investigate the Kelvin-Helmholtz instability of the gravity-driven stratified …
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Air Ingress and Heat-Driven Flow Relaminarization in a Very High Temperature Reactor (VHTR)
… <p>The first phenomenon is the issue of air ingress scenario under Depressurized Conduction Cooldown involving natural circulation of the gaseous coolant wherein a crack or breakage might occur in the reactor system due to an externally or environmentally initiated event leading to …
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Blind benchmark predictions of the NACOK air ingress tests using the CFD code FLUENT
… combined effects of natural convection during an air ingress event: diffusion, onset of natural circulation, graphite oxidation and multicomponent chemical reactions. MIT has been benchmarking JAERI tests using the FLUENT code for approximately three years [1]. This work demonstrated that the …
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Effect of helium injection on diffusion dominated air ingress accidents in pebble bed reactors
… thesis was to validate the sustained counter air diffusion (SCAD) method at preventing natural circulation onset in diffusion dominated air ingress accidents. The analysis presented in this thesis starts with a vertically oriented rupture of a coaxial pipe. Air enters into the reactor cavity …
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Air Ingress in HTGRs: the process, effects, and experimental methods relating to its investigation and consequences
… operating conditions. However, in the case of an air ingress accident, the oxygen introduced into the core can affect the integrity of the fuel graphite matrix. In this work a combination of computational models and mixed effects experiments were used to better understand the air ingress process …
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Investigation of MELCOR and STAR-CCM+ modeling capabilities to accurately predict air ingress rates from small breaks in high temperature gas-cooled reactors
… One specific scenario of concern is the air ingress following a primary loop break. Recent research has determined that small breaks are more likely than large double-ended guillotine breaks. The primary driving mechanism for the air ingress is the buoyant force due to the density …
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Analyzing FLUENT CFD models and data to develop fundamental codes to assess the effects of graphite oxidation in an HTGR air ingress accident
… is a faster running computer code to model air ingress events in high temperature gas reactors as a potential subroutine for nodal codes such as MELCOR to model air ingress events. Because of limitations found in FLUENT, and the limitations of the data set, a simple model of the effects of …
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Using the FLUENT computational fluid dynamics code to model the NACOK corrosion test
… heating and chemical reactions during an air ingress accident. Some MPBR-relevant experimental safety assurances have been benchmarked using FLUENT. Currently, there is a planned experiment involving natural convection flow and graphite corrosion at the Forschungzentrum Julich in Julich, …
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Elevated temperatures in waste containment facilities
… leading mechanism of elevated temperatures is air ingress, landfills are also experiencing elevated temperatures due to exothermic reactions from APW. Because aluminum production waste does not meet hazardous waste classification criteria, they are commonly disposed in MSW landfills. As a …
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A modelling methodology to quantify the impact of plant anomalies on ID fan capacity in coal fired power plants
… increased boiler flue gas exit temperatures; air ingress into the boiler; air heater inleakage to the flue gas stream; feed water heaters out-of-service; and condenser backpressure degradation. It was inter alia found that a low calorific value (CV) coal of 14 MJ/kg compared to a typical 17 …