Thesis (Ph. D.)--Washington State University, December 2009. / Title from PDF title page (viewed on Dec. 16, 2009). "Department of Chemistry." Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 117-123). Available also in a digital version from Dissertation Abstracts.

The Integral Inherently Safe Light Water Reactor (I2S-LWR) is a novel reactor concept which aims to apply safety-promoting features typical of small modular reactors (SMRs) to a large pressurized water reactor (PWR) of 3000 MWt, thus providing an option for a passively safe reactor to markets which would find greater economic benefit in a large reactor. Pushing the compact core of an integral reactor to 3000 MWt necessitates several design innovations to remain within safety margins while meeting the goal of increased power density. The I2S-LWR fuel assembly takes on a 19x19 lattice with reduced fuel rod dimensions relative to traditional Westinghouse-type 17x17 PWR fuel assemblies. It is anticipated that the I2S-LWR will eventually employ uranium silicide (U3Si2) fuel instead of uranium oxide (UO2) to improve thermal performance. These unique design features are closely tied to the I2S-LWR core neutronics, thereby necessitating a thorough investigation of reactivity control options. This thesis considers the design of both control rods and burnable absorbers on the basis of the I2S-LWR uranium silicide fuel assembly. Fuel assembly designs are considered with various control rod arrangements and burnable absorber layouts with several candidate absorber materials and concentrations. Viable fuel assembly designs must meet targets for reactivity and power peaking while satisfying constraints on core safety and cycle length. Designs are developed in a heuristic manner, and key performance metrics are processed at each iteration. Characteristics of common optimization algorithms are mimicked at a high level so as to guide the progression of design iterations. The optimized fuel assembly designs produced in this way are recommended for use in core loading pattern design.

No description available.

The Thelon basin, Nunavut, is similar to the uranium-producing Athabasca Basin, Saskatchewan; however, the uranium deposits associated with the Thelon Basin are poorly understood. The objective of this research is to develop a genetic model for the Bong uranium deposit, located in the Northeast Thelon region on the Kiggavik project of AREVA Resources Canada Inc. The Bong deposit formed in four stages. The first stage involved silicification of the host rocks. Stage 2 is characterized by pervasive argillization of the host rock and the formation of Stage A uraninite in veins and coating graphite (~1120 Ma). This stage is characterized by ~225°C fluids with calculated δ18O and δD values of -7.9‰ and -100.9‰, respectively. During Stage 3, organic matter formed, along fractures in permeable clay-rich alteration zones. At ~1040 Ma, an oxidizing fluid event (Stage 4) reconcentrated uraninite into redox fronts (Stage B) and altered Stage A uraninite to uranophane.

The independent formation cross-sections of ('84,86)Rb,('116m,117m,117g)In, and ('132,134m,134m+g,136)Cs from ('233)U(p,f) and ('235)U(p,f) reactions, and the independent formation cross-sections of ('72)Ga from ('233)U(p,f) reactions were measured radiochemically in the energy range 35 to 90 MeV. The isotopic distributions of Rb, In, and Cs from ('233)U(p,f) and ('235)U(p,f), and the isotopic distributions of Ga from ('233)U(p,f) were measured in the energy range 40 to 100 MeV using the on-line mass spectrometric technique; their relative yields were normalized to the independent formation cross-sections measured radiochemically. / The variations of the FWHM, mean mass numbers, and mean neutron-to-proton ratios of the isotopic distributions were studied. The experimental results indicate that the mean masses of the distributions vary linearly with their atomic numbers. In conjunction with the fission option of the pre-equilibrium/exciton model, the experimental data were used to estimate average total neutron yields. The results show that there are more neutrons emitted for near-symmetric fissions than for asymmetric fissions. The charge distribution postulates, ECD, MPE, and UCD, were examined. In the energy range studied the results indicate that the MPE postulate accounts for asymmetric fissions, and the UCD postulate accounts for near-symmetric fissions.

The Thelon basin, Nunavut, is similar to the uranium-producing Athabasca Basin, Saskatchewan; however, the uranium deposits associated with the Thelon Basin are poorly understood. The objective of this research is to develop a genetic model for the Bong uranium deposit, located in the Northeast Thelon region on the Kiggavik project of AREVA Resources Canada Inc. The Bong deposit formed in four stages. The first stage involved silicification of the host rocks. Stage 2 is characterized by pervasive argillization of the host rock and the formation of Stage A uraninite in veins and coating graphite (~1120 Ma). This stage is characterized by ~225°C fluids with calculated δ18O and δD values of -7.9‰ and -100.9‰, respectively. During Stage 3, organic matter formed, along fractures in permeable clay-rich alteration zones. At ~1040 Ma, an oxidizing fluid event (Stage 4) reconcentrated uraninite into redox fronts (Stage B) and altered Stage A uraninite to uranophane.

The Millennium uranium deposit is located 35 km north of the Key Lake mine, Saskatchewan. Uranium mineralization occurs in a variety of styles including (1) massive replacement, (2) fracture filling veins, (3) fine-grain aggregates associated with “mini” roll fronts, and (4) disseminated grains. The chemical Pb and isotopic 207Pb/206Pb ages of the massive (style 1), vein-type (style 2), and fine-aggregate (style 3) uraninite cluster at 1400-1200 and 1100-900 Ma. The ~1400 Ma ages coincide with the primary mineralization event for many of the uranium deposits (1550-1400 Ma) within the Athabasca Basin. Unlike other uranium deposits from the Athabasca basin, disseminated uraninite (style 4) have 207Pb/206Pb ages from 1770-1650 Ma. These ages are older than the depositional age for the Athabasca sediments (~1710 Ma) and are similar to the ages from the Beaverlodge vein-type uranium deposits.

No description available.

No description available.