Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1994. / Includes bibliographical references (leaves 79-82). / by Junne Lung Lin. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2004. / Includes bibliographical references (leaf 173). / This thesis 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). This pursuit involves implementing an appropriate methodology for design and optimization of hydride and oxide fueled cores. Core design is accomplished for 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. Considerable work has already been accomplished on the project; this thesis builds on this previous work. More specifically, it focuses on the steady-state thermal hydraulic and economic analyses for pressurized water reactor (PWR) cores utilizing UZrH₁.₆ and UO₂. A previous MIT study established the steady-state thermal hydraulic design methodology for determining maximum power from square array PWR core designs. / (cont.) The analysis was not performed for hexagonal arrays under the assumption that the maximum achievable powers for both configurations are the same for matching rod diameters and H/HM ratios. This assumption is examined and verified in this work by comparing the thermal hydraulic performance of a single hexagonal core with its equivalent square counterpart. In lieu of a detailed vibrations analysis, the steady-state thermal hydraulic analysis imposed a single design limit on the axial flow velocity. The wide range of core geometries considered and the large power increases reported by the study makes it prudent to refine this single limit approach. This work accomplishes this by developing and incorporating additional design limits into the thermal hydraulic analysis to prevent excessive rod vibration and wear. The vibrations and wear mechanisms considered are: vortex-induced vibration, fluid-elastic instability, turbulence-induced vibration, fretting wear, and sliding wear. Concomitantly with this work, students at UC Berkeley and MIT have undertaken the neutronics, fuel performance, and transient thermal hydraulic studies. / (cont.) With these results, and the output from the steady-state thermal hydraulic analysis with vibrations and wear imposed design limits, an economics model is employed to determine the optimal geometries for incorporation into existing PWRs. The model also provides a basis for comparing the performance of UZrH₁.₆ to UO₂ for a range of core geometries. Though this analysis focuses only on these fuels, the methodology can easily be extended to additional hydride and oxide fuel types, and will be in the future. Results presented herein do not show significant cost savings for UZrH₁.₆, primarily because the power and energy generation per core loading for both fuels are similar. Furthermore, the most economic geometries typically do not occur where power increases are reported by the thermal hydraulics. As a final note, the economic results in this report require revision to account for recent changes in the fuel performance analysis methodology. The changes, however, are not expected to influence the overall conclusion that UZrH₁.₆ does not outperform UO₂ economically. / by Carter Alexander Shuffler. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2005. / Includes bibliographical references. / This thesis contributes to the hydride nuclear fuel project being completed by UC Berkeley and MIT to assess the possible benefits of using hydride fuel in light water nuclear reactors (LWR's). More specifically, this thesis deals with the thermal hydraulic analysis of BWR reactors. Several papers and theses have already been written for this project, mainly focusing on PWR reactors. The primary goal of this thesis is to find the optimal fuel rod lattice pitch and diameter such that a reactor can safely operate at the highest possible power. This fuel geometry is found out of hundreds of possible choices by using a script to automate a parametric study. A similar process was completed by an MIT graduate student for PWR reactors. While this thesis demonstrates the ability to use such a method for thermal hydraulic BWR analysis, there are some shortcomings which are mainly due to the difficulty of obtaining proprietary information about BWR nuclear reactors. All results hold equally for uranium dioxide as well as hydride fuel since the design limits imposed, critical heat flux, maximum flow velocity and pressure drop constrain only pin array geometry and diameter. It is shown that applicable uranium oxide and hydride fuel limits are both met within the constraints imposed by these three limits which were applied. / (cont.) The final analysis of this report shows a possible reactor power improvement of order 30% but this is based on several analysis selections which introduce error and/or a degree of unrealism into the analysis. First the EPRI critical heat flux correlation was used versus a more appropriate critical power correlation Second the expedient of using a fixed mass flux was adopted which caused the hot channel exit quality to change with power changes. This was done since the means to keep the ratio of reactor power to mass flow rate constant which would have maintained constant exit quality over the geometry map explored by scripting could not be developed in the time available for this work.., Hence definite conclusions on achievable BWR core power over the range of geometries investigated are not available and hence warrant further investigation. More importantly the accomplishment of this thesis is the demonstration that the scripted methodology described in this paper can be used to assess thousands of different reactor parameters in order to optimize reactor power. / by John Everett Creighton. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2005. / Includes bibliographical references (p. 173-182). / This thesis presents Nuclear Magnetic Resonance (NMR) studies of gas flow dynamics in porous and granular media by using laser-polarized ¹²⁹Xe . Two different physical processes, the gas transport in porous rock cores and the mass exchanges between different phases in fluidized granular systems, were investigated and new experimental methods were designed to measure several important parameters characterizing the two systems. Methods for measuring the parameters had been either unavailable or significantly limited previously. The research involved modeling the gas flow in porous and granular media by relating the dynamics of spin magnetization to the interesting parameters, as well as correspondingly designing new measurement methods and verifying them on the laboratory test beds. We proposed a simple method to measure two important parameters of reservoir rocks, permeability and effective porosity, by probing the flow front of laser-polarized xenon gas inside the rock cores. The method was thoroughly tested on different categories of rocks with permeability values spanning two orders of magnitude, and the results were in agreement with those from the established techniques. / (cont.) The uniqueness in the work is that the fast method developed is capable of measuring the two parameters simultaneously on the same setup. Bubble-emulsion exchange and emulsion-adsorption exchange in a fluidized bed are two processes crucial to the efficiency of many chemical reactors working in bubbling regime. We used differences in T2 and chemical shift to contrast the three phases in the xenon spectra, and designed methods to measure the inter-phase exchange rates. The measured results of the bubble-emulsion and emulsion-adsorption exchange rates agreed well with predictions based on available theory. Our approach is the first to non-invasively probe natural bubbles in a three-dimensional bed, and to measure the exchange rate between the emulsion phase and multiple bubbles. / by Ruopeng Wang. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1995. / Includes bibliographical references (leaves 142-143). / by Gabriel Dalporto. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1995. / Includes bibliographical references (leaves 145-146). / by Bronislav Guimpelson. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1995. / Includes bibliographical references. / by Mirela Gavrilas. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1995. / Includes bibliographical references (leaves 103-104). / by Jody Christopher Miller. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1996. / Includes bibliographical references (leaves [567]-610). / by Joseph Jerome Bambenek. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1996. / Includes bibliographical references (leaves 79-80). / by Sung-Min Choi. / M.S.