U-Pu-Zr nuclear fuels experience a redistribution of constituents and a number of phase transformations when subjected to the thermal gradient present in nuclear reactors. This redistribution and phase separation leads to several undesirable fuel performance issues. In an effort to better understand how different alloys compositions are affected by this thermal gradient, we utilize the recently introduced Hybrid Potts-phase Field Method to study the U-Pu-Zr system. The recently introduced Hybrid method couples microstructural and compositional evolutions of a system so that the two phenomena can be studied together rather than separately, as is frequently done. However, simulation of the U-Pu-Zr system required several adaptations to the modeling framework. First the model was adapted to incorporate a thermodynamic database for free energy calculations, as well as thermal diffusion (the Soret effect). These abilities were tested in the Al-Si system. Second, the modeling framework was expanded to simulate three component systems such that ternary U-Pu-Zr alloys could be studied.Simulations capture constituent redistribution and the appropriate phase transformations as compared to experimentally irradiated a U-16Pu-23Zr (at%) nuclear fuel. Additional simulations analyze constituent redistribution over the entire spectrum of U-Pu-Zr compositions. Analysis of these simulation results indicate alloys that are likely to experience minimal constituent redistribution and fewer phase boundaries, such that their fuel performance should be improved. The outcomes of the work include a coupled microstructural-compositional modeling framework for ternary alloys and suggestions of U-Pu-Zr alloys that could lead to improved fuel performance.

<p> This thesis is concerned with the determination of the thermodynamics of the Fe-V-O system. </p> <p> In the first part the thermodynamics of liquid Fe-V-O alloys were studied in the temperature range of 1550-1700ºC using H₂O/H₂ equilibrium and/or an oxygen probe. 1st and 2nd order interaction parameters between V and O were determined, and the deoxidation reactions occurring when V is used as a deoxidizer were studied. Deoxidation diagrams are presented for V concentrations up to 12 wt. %. </p> <p> In the second part the thermodynamic equilibria between the lower oxides of vanadium (V - VO₀ٜ₂₋ₓ, VO₀ٜ₂₊ₓ - VO₁₋ᵧ, VO₁₊ᵧ - VO₁ٜ₅) were determined in the range 800-1400ºC using a solid state EMF technique, and the free energy of the formation of the oxides VO₀ٜ₂₊₍₋₎ₓ, VO₁₊₍₋₎ᵧ, VO₁ٜ₅ was estimated. </p> / Thesis / Doctor of Philosophy (PhD)

Abstract Specifics included in thesis. / Thesis / Master of Engineering (MEngr)

<p> LiYO2 is a lithium ion conductor stable to pure lithium metal. The goal of the present work was to design and construct an electrochemical cell and demonstrate the use of LiYO2 as an electrolyte since this has never been previously done. The electrolyte was fabricated by slip casting in powder molds. A Y2O3-MgO composition was identified and used to fabricate a lid for the cell. Impervious cells were obtained by liquid phase joining and sintering techniques. Heating rate was found to be a key parameter in the success of this procedure. The cell was evaluated in terms of stability as a sensor and chemical pump by measuring EMF for two different Li-Zn alloys between 250 and 600°C. The configuration was as follows: (RE) (-) Ta Li,Sn | LiYO2 | Li,Zn Ta (+) (WE)</p> <p> The cell showed no significant attack after 40 days working with pure lithium. Stability and reproducibility of EMF values was obtained for the concentrations of Li studied. Solidus and liquidus temperatures were determined for the 5 and 10 mol% Li compositions in good agreement with published phase diagrams. Variations of EMF with respect to temperature or concentration followed the expected thermodynamic relationships. Results indicate that the LiYO2 electrolyte cell could be useful in assessment of the thermodynamics of lithium alloys.</p> / Thesis / Master of Engineering (MEngr)

The favorable interaction between proteins and nanoparticles has sparked potential applications of nanotechnology in medicine, and the unique electronic and chemical properties of nanoparticles also provide novel strategies for protein-related therapeutics. The formation of the biocorona has attracted substantial interest over the past decades. For instance, as a potential drug delivery mechanism, protein-coated nanoparticles can improve biocompatibility and increase targeting ability. However, the mechanistic details of protein-nanoparticle interactions remain poorly understood. For example, it is currently impossible to predict the orientation and structure of proteins on the nanoparticle surface, as well as the fate of the biocorona in vivo. Since the composition of the biocorona determines the biological response, identifying and stabilizing the biocorona seems critical for the further development of applications in biological system. In this study, we investigated the physicochemical properties of protein interactions with gold nanoparticles (AuNPs). Firstly, we developed an NMR-based approach for measuring the stoichiometry of protein adsorption to AuNPs, which can be generally applied to globular proteins of different size. Quantitative analysis enabled us to create a protein binding model that involves an initial association, structure reorientation and irreversible adsorption. Secondly, we measured the protein hydrogen-deuterium exchange rates and found that they were unperturbed in the presence of AuNPs, suggesting that proteins retain their globular structure upon adsorption. Finally, we investigated the electrostatic contribution to binding, and we identified a dynamically changing surface in which the factors of net charge, binding affinity and protein size play distinct roles at different phases.

No description available.

No description available.

Yes / Despite the fact of being intensive energy consumption, MSF is a mature technology that characterised by a high production capacity of high-quality water. The multistage flash (MSF) desalination process is one of the prominent thermal desalination used in the industry of seawater desalination to produce high quantity and high quality of freshwater. However, this process consumes large amount of energy and faces thermal limitations due to its high degree of exergy destruction at several units of the process. Therefore, the research of MSF is still existed to elevate the performance indicators and to resolve the concern of high energy consumption. To rectify these limitations, it is important to determine the units responsible in dissipating energy. This study aims to model an industrial MSF process validated against real data and then investigate the exergy destruction and thermodynamic limitations of the process. As a case study, Azzour MSF seawater desalination plant, located in Al Khiran in Kuwait is under the focus. A comprehensive model is developed by analysing several published models. Specifically, the calculation of exergy destruction has embedded both physical and chemical exergies that identified as a strong point of the model developed. As expected, the highest exergy destruction (55.5%) occurs within the heat recovery section followed by the brine heater with exergy destruction of 28.26% of the total exergy destruction. This study identifies the sections of the industrial process that cause the highest energy losses.

Two magmatic systems were investigated using different petrological tools: 1) Origin of Ponza trachyte was studied combining data from MI with trends predicted by thermodynamic modeling. MI data were compared with known phase relations in the ternary feldspar and anorthite-diopside-albite systems to constrain the parameters used in the modeling. MI data are consistent with melt evolution from a basaltic parent via a fractional crystallization mainly of pyroxene and feldspars. These data and the results from the modeling, suggest a genetic link between the Ponza trachyte and coeval alkali olivine basalts on the nearby Ventotene Island. 2) We evaluated the range of magmatic temperatures within the crystallization interval for a basanite with different olivine-spinel geothermometers. While olivine spinel pair records the evolution of the basanite during crystallization, low temperatures calculated with the geothermometers are unrealistic. This is likely due to the presence of significant amounts of Ti in our magmatic spinels. Indeed Ti is not taken into account in the geothermometers. We tested the possibility of accounting for the presence and effects of Ti using a linear correction for the Fe+2 content in our spinels. While this generated more realistic temperatures at the low end of the range, it also increased the dispersion in the data, suggesting that spinel behavior is more complex and that the presence of Ti affects content and site occupancy of other elements as well. / Ph. D.

Fluoride salt-cooled high-temperature reactor (FHR) is a safer and potentially less expensive alternative to light water reactor due to the low pressure of primary system, passive decay heat cooling system, chemically inert coolant salt, and high-temperature power cycle. However, one challenge presented by this reactor is that fission products may leak into the primary system from its TRISO particle fuel during normal operation. Consequently, the circulating fission products within the primary coolant would be a potential radioactive source. On the other hand, the containment material of the molten salt such as nickel-based alloys may be corroded, and its species may stay in the salt. Thus, the installment of the primary coolant clean-up system and the study on the contaminant species' chemistry and separation are necessarily needed. Electrochemical separation technique has been proposed as the online coolant clean-up method for FHR for removing some impurities from the salt such as lanthanides and corrosion products. The present research focuses on the electrochemical separations of fission products and corrosion products in molten FLiNaK salt (46.5LiF-11.5NaF-42KF mol%) which is the surrogate of the primary coolant candidate FLiBe (67LiF-33BeF2, mol%) for FHR. The main objective is to investigate the electrochemical behaviors of fission products and corrosion products in molten FLiNaK salt to achieve its separations, and provide fundamental properties to instruct the conditions needed to be applied for a desired electrochemical separation. La and Ce are two main elements concerned in this study since they are major lanthanide fission products. Electrochemical behavior of LaF3 in molten FLiNaK salt was studied on both W and Mo inert working electrodes. Although the standard reduction potential of La (III) is more cathodic than that of the primary salt melt constituents K (I) and Na (I), the electrochemical separation of La from molten FLiNaK salt was achieved by merely using inert working electrode because of the formed LaF63- when KF or NaF exists as the salt constituents. Fundamental properties of La in molten FLiNaK salt were also studied at various situations by electroanalytical methods including cyclic voltammetry (CV), chronopotentiometry (CP), and potentiodynamic polarization scan (PS). Ce is another fission product to be separated out from molten FLiNaK salt. Both inert (W) and reactive working electrodes (Cu and Ni) were utilized to realize the extraction of Ce. The electrochemical behaviors of Ce observed on inert W electrode are similar to the ones obtained in FLiNaK-LaF3 system. Reactive electrodes Cu and Ni were used to precede the electrochemical deposition potential of Ce by forming intermetallic compounds. It turned out only Ni electrode was feasible for preceding the deposition potential and the intermetallic compound was identified as CeNi5. The dissolution of chromium metal in the form of chromium fluoride into molten FLiNaK salt is the main concern of alloy corrosion in FHR. To understand the alloy corrosion and removal of the corrosion products from the FHR salt coolant, the electrochemical behavior and fundamental properties of Cr in molten FLiNaK salt were investigated in the present study as well. A new analysis method for the Cr two-step electrochemical reaction in the salt was developed. The method can be applied to other two-step reactions as well. Liquid bismuth was proposed to be the extraction media for liquid/liquid multistage separation of fission products in molten salt reactor. It also can be used as the cathode to extract the fission product of which the electrodeposition potential is close to or more negative than that of the main constituents of molten salt. Activity and activity coefficient are essential factors for assessing the extraction behavior and viability of bismuth in separating fission products. Hence, in the present study, the activity and activity coefficient of fission products and alkali metals (Li and K) at different concentrations and temperatures were determined by experiment and simulation methods respectively. To conduct the parametric study for the electrochemical reaction process and predict fundamental properties, an electrochemical model including single-step reversible, irreversible, and quasi-reversible reactions, multiple-reaction, and two-step consecutive charge transfer reaction was developed based on MOOSE. Although the model was not applied to analyze the experimental data in the present study, this model provides an efficient and easy way to understand the effect of various parameters on electrochemical reaction process. The present study supplied a comprehensive study on the electrochemical separation of fission products and corrosion products in molten FLiNaK salt and will contribute greatly to the development of FHR. / Doctor of Philosophy / There is a significant increased demand for the generation of electricity with the fast development of modern society and economy. For well over 100 years, the dominant energy sources for producing electricity in the industrialized world are fossil fuels, notably coal, oil, and natural gas. The generation of electricity from fossil fuels is a major and growing contributor to the emission of greenhouse gases that contribute significantly to global warming. As clean and efficient energy, the nuclear power source has been an attractive alternative to traditional fossil fuels. The fluoride salt cooled high temperature reactor (FHR) is a promising Generation-IV advanced nuclear reactor. FHR is a salt-cooled reactor in which the core contains a solid fuel and liquid salt coolant. It combines attractive attributes from previously developed reactors and has the advantages of, for example, low-pressure operation, high temperature power cycle, and passive decay heat rejection. However, the primary salt coolant can unavoidably acquire fission products from the fuel particles and corrosion products from structural material corrosion. Therefore, it is necessary to have a primary coolant clean-up system installed in the FHR to mitigate the contamination and ensure the continued operation of the reactor. Electrochemical separation technique has been proposed as the online coolant clean-up method for FHR. Electrochemical separation can be typically done in a three-electrode cell system (working, counter, and reference electrodes). Through applying a proper electrical potential or a current, the target metal ions in the molten salt will be deposited on the working electrode. In that way, the contaminants, including fission products and corrosion products, can be taken out with a working electrode from the molten salt coolant. In this study, the fundamental behaviors of separation of La, Ce (represent lanthanide fission products) and Cr (represents corrosion products) in FLINAK were investigated. To achieve their separations, the present dissertation provided a comprehensive study about the electrochemical behaviors of La, Ce, and Cr species in molten FLiNaK salt at various situations, and relevant fundamental properties for guiding the conditions needed to be applied for the desired electrochemical separation. Considering the use of liquid bismuth as the extraction media for liquid/liquid separation and the electrode for electrochemical separation of fission products the fundamental properties of fission products and alkali metals in liquid bismuth are also determined in the present study to evaluate the separation behavior and viability. Finally, an electrochemical model for understanding the electrochemical process in the FHR salt coolant clean-up was developed. Overall, the work performed in this study will contribute greatly to facilitate the FHR development.