Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007. / Includes bibliographical references (leaves 40-41). / This thesis analyzes a sample of 15 fuel-handling events from the past ten years at commercial nuclear reactors with significant human error contributions in order to detail the contribution of human error to fuel-handling activities, emphasizing how latent conditions can directly contribute to events. In particular, procedural inaccuracies often create conditions that lead to the development of errors related to maintenance work practices. This would be of significant concern for a pre-closure safety assessment for a geologic repository for spent nuclear fuel and high-level radioactive waste, where many fuel-handling work activities would be performed. Specific emphasis is placed on fuel movement activities and control of ventilation systems, which could significantly impact worker and public health and safety in the case of a fuel-handling accident. / by Bradley Sutton. / S.B.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2001. / Includes bibliographical references (leaves 124-126). / Tubular hydroforming is gaining importance in the automotive industry by enabling parts consolidation, weight reduction and performance enhancement. While current automotive applications use almost exclusively mild steel, other advanced steel and aluminum alloys are being discussed for use in the future. This thesis evaluates the economics of hydroforming three representative materials - mild steel, dual phase 600 steel and aluminum 5754 - using technical cost modeling. Costs are analyzed for the entire hyclroforming value stream, from coiled metal sheets to hydrofonned components, for both geometrically equivalent and functionally equivalent hydroformed components. Design conditions of constant load to failure and constant defection are used to derive functional equivalence. Results show that manufacturing costs are most sensitive to the maximum calibration pressure required for hydroforming. While the costs of processing aluminum components are less than those of functionally equivalent steel components, greater aluminum raw material costs of lead to greater total component costs compared to steel. Substitution of advanced materials is not as cost effective a weight reduction strategy as increasing section diameter and thinning walls of mild steel components, assuming no package constraints. / by Bruce A. Constantine. / S.M.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2014. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 123-139). / This thesis studies radiation-induced mixing at interfaces between low solubility metals using molecular dynamics (MD) computer simulations. It provides original contributions on the fundamental mechanisms of radiation-induced mixing and morphological stability of multilayer nanocomposites under heavy ion or neutron radiation. An embedded atom method (EAM) interatomic potential is constructed to reproduce the main topological features of the experimental equilibrium phase diagram of the Cu-Nb system in both solid and liquid states. Compared with two previously available EAM Cu-Nb potentials, the phase diagram of the current potential shows better agreement with the experimental phase diagram. The newly constructed potential predicts that the Cu-Nb liquid phase at equilibrium is compositionally patterned over lengths of about 2.3 nm. All three Cu-Nb potentials have the same solid phase behavior but different liquid phase properties, serving as a convenient set of model systems to study the effect of liquid phase properties on radiation-induced mixing. To study radiation-induced intermixing, a specialized MD simulation is developed that models multiple 10 keV collision cascades sequentially up to a total dose of ~5 displacements per atom (dpa). These simulations are comparable to experiments conducted at cryogenic temperatures. Mixing is modeled using all three Cu-Nb potentials and found to be proportional to the square root of dose, independent of interface crystallography, and highly sensitive to liquid phase interdiffusivity. It occurs primarily by liquid phase interdiffusion in thermal spikes rather than by ballistic displacements. Partial de-mixing is also seen within thermal spikes, regardless of liquid phase solubility, which is explained by segregation of impurities into the liquid core of the thermal spikes. Additional MD and phase field simulations are carried out on Cu-Nb multilayered nanocomposites with individual layer thicknesses above 1 nm. These simulations demonstrate that Cu-Nb multilayers with individual layer thicknesses above 2-4 nm remain morphologically stable when subjected to 100 keV collision cascades, characteristic of neutron or heavy ion irradiation. The probability of morphological instability rapidly increases as the layer thickness decreases to 1 nm, which is due to overlap of zones of liquid-like interdiffusion inside radiation-induced thermal spikes at neighboring interfaces in the multilayer. This work shows that to design morphologically stable radiation-tolerant nanocomposites, it is desirable to a) choose low solubility metals with small liquid phase interdiffusivity as the constituents, and b) use a microstructural length scale larger than twice the size of the interdiffusion zone inside thermal spikes. / by Liang Zhang. / Ph. D.

Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references. / Nuclear Renewable Oil Shale Systems (NROSS) are a class of large Hybrid Energy Systems in which nuclear reactors provide the primary energy used to produce shale oil from kerogen deposits and also provide flexible, dispatchable electricity to the grid. Kerogen is solid organic matter trapped in sedimentary shale, and the formations of kerogen oil shale in the western United States are the largest and densest hydrocarbon resource on the planet. When heated above 300 °C, kerogen decomposes into oil, gas, and char. NROSS couples electricity and transportation fuel production in a single operation, reduces lifecycle carbon emissions from the fuel produced, improves economics for the nuclear plant, and enables a major shift toward a very-low-carbon electricity grid. The nuclear reactor driving an NROSS system would operate steadily at full power, providing steam for shale heating in closed steam lines when the price of electricity is low and electricity to the grid when the price of electricity is high. Because oil shale has low thermal conductivity, heat input to the shale can be cycled as needed without disrupting the steady increase in average temperature. The target average shale temperature of 350 °C would be reached over 2 years using two heating stages in the baseline configuration driven by light water reactors. First stage heating brings the shale to an intermediate temperature, assumed to be 210 °C in this study. The second heating stage isolates the steam delivery line from the reactor and uses electricity, purchased when prices are low, to increase steam temperature and bring the shale to 350 °C. This capacity to absorb low price electricity mitigates the tendency for electricity prices to collapse to zero, or potentially negative values, during periods of peak wind and solar output. The analysis herein shows that liquid fuels produced by a baseline NROSS would have the lowest life cycle greenhouse gas impact of any presently available fossil liquid fuels and that operation as part of an NROSS complex would increase reactor revenues by 41% over a stand-alone baseload reactor. The flexible, dispatchable electricity provided by NROSS could also enable the transition to a very-low-carbon grid in which renewables are widely deployed and the NROSS provides variable output to balance their uncontrolled output to meet demand. Fully deployed, NROSS could require tens or hundreds of reactors. Large fleet operations and local mass production of the necessary hardware could bring about substantial reductions in system cost as development proceeds, potentially offering a pathway to jump start and maximize the realization of the mass production cost savings envisioned for small modular reactors. The development pathway to achieve large scale NROSS deployment will be complicated, however, requiring involvement from many government agencies, a demonstration system, and a complex commercialization effort with partnered nuclear vendors, utilities, and petroleum system developers. / by Daniel Joseph Curtis. / S.M.

Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (page 31). / Both biological and synthetic materials crosslinked via metal coordinate dynamic chemistry display interesting advanced behavior. In particular, coordinate networks have been shown to form self-healing, self-assembling, and stimuli-responsive behaviors through its tunable optical and mechanical properties as well as its ability to for dynamic networks. However, while the majority of research has focused on characterization of bulk coordinate networks, coordinate complexes have also been shown to be useful in molecular film formation [1 and 2]. This study investigates the mechanical and optical properties of tannic acid and 4 arm catechol polyethylene glycol based coordinate network films. It shows that these films can contribute to energy dissipation and undergo pH-induced optical shifts when used as coatings on soft hydrogels. It also provides evidence that the molecular architecture of the network formers may have considerable effect on the properties and behavior of coordinate network films. Ultimately this work lays the foundation for further investigation of the underlying mechanisms and engineering potential of coordinate network based films. / by Rebecca Anne Gallivan. / S.B.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 165-181). / The route to enhanced functionality in electronic and magnetic devices is often through materials engineering and the use of new materials structures. Oxides, in particular, exhibit a wide range of highly tunable properties due to the interplay of lattice, orbital, charge and spin degrees of freedom. Recently, a new paradigm for epitaxy has been studied, where two oxide phases self-assembled into a vertical columnar morphology, with epitaxially strained interfaces perpendicular to the substrate. Through appropriate materials selection and strain tuning, the interfaces in these vertically aligned nanocomposites exhibit exciting properties such as high conduction at interfaces, enhanced ferroelectricity and magnetoelectric coupling, which are often absent or occur at a lower magnitude in single phase materials. In particular, magnetoelectric multiferroics, materials that exhibit two or more ferroic orders (such as ferromagnetism and ferroelectricity) and also exhibit electric field control of magnetism, have been widely explored, due to their utility in realizing novel low power multifunctional devices. Few materials exhibit robust room temperature multiferroicity, and thus vertical nanocomposites such as BiFeO₃-CoFe₂O₄ (BFO-CFO) which consist of magnetic CFO pillars in a matrix of ferroelectric BFO coupled via strain provide an exciting path to create artificial magnetoelectric multiferroics. In this thesis, we explore the magnetic, multiferroic and magnetoelectric properties of BFOCFO nanocomposites. Exploiting the rich strain tunability of BFO, we utilize different ways to modulate the structure of BFO in the BFO-CFO nanocomposites. Using different crystal substrates, we demonstrate that the presence of CFO offers additional parameters by which to tune the structure of BFO. In order to enable reliable device use, we need to understand and control the various interactions in BFO-CFO system. We demonstrate that composition tuning is an effective way to systematically tune the anisotropy of the magnetic pillars, thereby controlling their magnetostatic interactions. We probe the magnetoelectric coupling between the BFO and CFO phases by using Scanning Probe microscopy. By demonstrating tunability of the ferroelectric and magnetic phase of BFO-CFO nanocomposites and exploring the quantification of magnetoelectric coupling at the nanoscale, this thesis could enable intelligent design and optimization of the multiferroic and magnetoelectric properties in oxide nanocomposites. / by Shuchi Ojha. / Ph. D.

Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2013. / "June 2013." Cataloged from PDF version of thesis. / Includes bibliographical references (pages 36-37). / Approximately 62.8 trillion kJ are consumed annually worldwide in the manufacturing process of traditional clay tiles. With this in mind, the goal of this project was to develop an eco-friendly alternative to clay tiles that maintain the ASTM building code standards. Through experimentation, a fly ash tile was produced that consumes 99% less energy in the manufacturing process than commercial clay tiles. The final product is a fly ash tile composed of two classes of fly ash, water, and several additives to strengthen the material. Standard ASTM tests were conducted. This fly ash tile is an energy efficient clay-tile alternative that excels in many mechanical properties. / by Jaclyn Schein. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 399-417). / The dramatic change in the international security environment after the collapse of the bipolar system has had a negative impact on the effectiveness of the existing nuclear non-proliferation regime. Furthermore, the success of the Pakistani Gas Centrifuge Enrichment Technology (GCET)- based nuclear weapons program has imposed a great challenge on the Nuclear Nonproliferation Treaty (NPT) regime. In this context, this study tried to answer two questions: (a) what is the probability of proliferators successfully producing Highly Enriched Uranium (HEU) at Gas Centrifuge Enrichment Plants (GCEPs) and (b) how effective is the current NPT regime in dealing with this issue. In order to tackle these two questions, an integrated methodology is used that reflects all factors affecting the nuclear proliferation on the front-end of the nuclear fuel cycle. A quantitative assessment of the proliferation risks of producing HEU for multiple scenarios is presented using success tree models, uncertainty analysis, sensitivity analysis, importance measures, and expert opinion. This assessment identifies the factors that can reduce the proliferators' success of producing HEU, which will be helpful in prioritizing the use of the IAEA's limited resources. / (cont.) The study found that legal capabilities of the NPT regime are more problematic than technological capabilities in preventing proliferators from producing HEU at GCEPs, since the United Nations Security Council (UNSC) is the only NPT regime component that has compliance-enforcing resources. This study recommends three approaches as follows: First, the NPT regime should take a multi-faceted approach that incorporates all NPT regime components into each step of nuclear weapons program development. Second, the NPT regime should impose nuclear elements control via Multilateral Export Control Regimes (MECRs). Third, the NPT regime should develop an approach that challenges HEU production from both technological- and legal points of view. Since law governs technological capability, a multidimensional approach that includes this relationship would be more effective than an approach that focuses on either aspect individually. / by Taeshin Kwak. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2003. / Includes bibliographical references (p. 135-139). / by Michael J. Tarkanian. / S.M.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2016. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 121-139). / In order for alkali-ion batteries to gain widespread adoption as the energy storage technology of choice for transportation and grid applications, their energy must be improved. One key step towards this necessary improvement is the development of new battery cathode materials. In this thesis, two classes of polyanionic materials are examined as candidate cathodes for alkali-ion batteries: Li-containing carbonophosphates for Li-ion batteries and Na-containing fluorophosphates for Na-ion batteries. High-throughput ab initio calculations have previously identified carbonophosphates as a new class of polyanionic cathode materials. Li₃MnCO₃PO₄ is the most promising candidate due to its high theoretical capacity, predicted multi-redox activity, and ideal voltage range. However, a major limitation of this material is its poor cyclability and experimental capacity. In this work Li₃Fe₀.₂Mn₀.₈CO₃PO₄ is synthesized to combine the high theoretical capacity of Li₃MnCO₃PO₄ with the high cyclability of Li₃FeCO₃PO₄. Li₃Fe₀.₂Mn₀.₈CO₃PO₄ outperforms both Li₃MnCO₃PO₄ and Li₃FeCO₃PO₄, showing a reversible capacity of 105 mAh/g with little capacity fade over 25 cycles. However, poor thermodynamic stability of these compounds, particularly at partially delithiated compositions, prevents carbonophosphates from being seriously considered as a viable Li-ion cathode. Fluorophosphate cathodes are currently one of the most promising polyanionic sodium-ion battery cathodes due to their high energy density and cyclability. To further improve fluorophosphate cathodes, their capacity must be increased by using Na sites that had not been accessed prior to this work. In this thesis, reversible electrochemical Na+ insertion into Na₃V₂(PO₄)₂F₃ is demonstrated. To further improve fluorophosphate cathodes by using its newly discovered insertion capacity, novel Na₃[M]₂(PO₄)₂F₃ cathodes, with {M = Fe, Ti, V}, are synthesized and evaluated. Seeing no improvement, the question of what specific mechanism limits fluorophosphate cathode capacity is addressed. For this, the synthesis, electrochemical characterization, and computational examination of a specifically designed test system, Na₃GaV(PO₄)₂F₃, is reported. This leads to the conclusion that large diffusion barriers at high sodiations impose a kinetic limit on Na+ insertion in fluorophosphate cathodes, as opposed to limits in transition metal redox activity. / by Ian Lawrence Matts. / Ph. D.