This dissertation surveys the history of tritium beginning in Ernest Rutherford's lab in 1934 with its discovery and ending at the Fukushima Daiichi disaster site in 2023 when TEPCO began releasing tritiated wastewater into the Pacific ocean. In this time, expert conceptions of tritium have experienced interdependent and overlapping phases. Each phase is characterized by a dominant "nuclearity" and situated in context of "nuclear exceptionalism" (Hecht 2014) that directly and indirectly affects material conditions, elite decision-making, and radiological impacts on the environment and human health. Because it is pervasive, diffuse, and laborious to measure, a great deal of uncertainty surrounds tritium's contribution to radiological risks. Beyond various commercial and scientific uses, it is also integral to both nuclear energy as a waste and nuclear weapons as a mechanism for dramatically increasing explosive yields. This versatile and powerful material operates at the technological nexus of two existential risks for humanity: climate change and nuclear weapons. I divide the history of tritium into three distinct phases. First, super nuclearity characterizes early designs for the "superbomb" by Manhattan project scientists who believed vast amounts of tritium would be required. This phase extends to the late 1950s when thermonuclear warheads based on more feasible designs requiring significantly less tritium were beginning to be incorporated into the U.S. nuclear weapon stockpile. Second, special nuclearity describes the status of tritium throughout the Cold War as a critical nuclear weapons material that was referred to and treated as a special nuclear material (SNM) in practice even though it was never legally defined as such. Third, byproduct nuclearity is the current post-Cold War paradigm defining tritium as a form of incidental waste or as an innocuous "other accountable material" intentionally produced by the nuclear fission process. While tritium's super nuclearity proved to be an animating fiction with political and material impacts on the early U.S. post war nuclear weapons program, tritium's special and byproduct nuclearities have since been fully embodied in technological artifacts—primarily nuclear weapons and nuclear power plants—and remain in dynamic tension. Tritium does not fit neatly into existing nuclearity narratives. It is accurately referred to as both "highly" and "weakly" radioactive. Having a half-life of ~12 years and being the lightest radioisotope, it has high activity by weight, but when it decays into stable helium-3 it emits only a relatively weak beta particle which poses a potential risk as internal dose. I argue that the nuclearity processes constituting various conceptualizations of tritium provide insight into navigating the complex sociotechnical relationships between humans and nuclear technology. Additionally, I anticipate tritium's next nuclearity transformation as reactor fuel for a still nascent fusion power industry. I argue that rather than allowing fusion energy proponents to dictate the next phase of tritium's nuclearity, efforts should be made to assess and synthesize salient aspects of this unique material to provide a more holistic accounting of its risks, benefits, and tradeoffs. / Doctor of Philosophy / Hydrogen is the most abundant element in the universe. It fuels the stars and forms compounds like water that are essential to life. Most atoms of hydrogen contain one proton and one electron, but hydrogen also has two less common, naturally occurring "heavy" forms that additionally contain neutrons. One is deuterium, which contains one neutron and can be concentrated to make heavy water. The other type of hydrogen is tritium, which contains two neutrons. This dissertation is about tritium, an extremely rare and valuable material that can be used to produce a faint green light source without electricity, to increase the explosive power of nuclear weapons, or to fuel fusion power reactors. Tritium is also a radioactive waste material produced by both military and civilian nuclear activities. I divide the history of tritium into three phases: super, special, and byproduct. When tritium was first discovered in 1934, it was an exotic scientific curiosity. During the 1940s, scientists with the Manhattan Project began working out how tritium could be weaponized into a "superbomb" that would be vastly more powerful than the atomic bombs the U.S. dropped on Japan in WWII. While the "superbomb" designs proved to be unviable, powerful hydrogen weapons were developed in the 1950s that relied on tritium alongside specially prepared masses of uranium and plutonium. To limit the spread of nuclear weapons, these special forms of uranium and plutonium have been tightly regulated as special nuclear material (SNM). Tritium, on the other hand, never met the legal definition of SNM but was nonetheless treated as a "special" material throughout the Cold War until the 1990s. Tritium has remained a critical material for all modern nuclear weapons, but in the last thirty years it has been primarily thought of and regulated as a byproduct material. Because the radiological risks posed by tritium are ambiguous and technically challenging to measure at low concentrations, many proponents of nuclear technologies suggest that they are negligible and, at the same time, anti-nuclear activists claim that more research is needed to show tritium's dangers clearly. I argue that it is important to prioritize a more thorough assessment of tritium's radiological risks and role in nuclear weapons before the implementation of large-scale fusion technologies that will require the production of many thousands more times the amount of tritium currently available in the world.

The research work reported in this dissertation is focused on exploring the systematic syntheses and characteristics of lanthanide-containing functional materials. Lanthanides have interesting properties that arise as a consequence of f-electrons, namely, magnetism, luminescence, and flexible coordination sphere. These studies were extended further into heterometallic systems containing transition metal ions, specifically Ni(II) and Co(II), to further explore the behavior of lanthanides in functional materials with addition of transition metal ions. The results include the high nucleraity lanthanide hydroxide clusters and metal-organic frameworks which showed potential applications in catalysis, separations, solid-state light-emitting devices and magnetism. Chapter 1 provides background on lanthanides and different types of lanthanide-containing materials, their properties, and potential applications followed by a synopsis to the research work in each chapter. In Chapter 2, the synthesis, structure characterization, magnetic studies and solution stability studies of a novel class of high-nuclearity lanthanide hydroxide cluster complexes {Ln54} with Chromogen I, a ligand transformed from in situ N-Acetyl-D-glucosamine are summarized. Attention is focused on this ligand transformation since it shows a possible pathway for selective and efficient transformation of biomass into useful chemicals with the unique coordination chemistry of lanthanides. The remainder of this chapter is focused on using hydroxylcarboxylic acids for the formation of high-nuclearity lanthanide hydroxide clusters with the aim of expanding the array of ligands that can be utilized for developing these systems. Chapter 3 discusses the synthesis, structural characterization and photoluminescence properties of a novel series of lanthanide metal-organic frameworks utilizing iminodiacetic acid as bridging ligand. The possibility of luminescence color tuning employing mixed metal system containing Eu and Tb was shown. The lifetimes for the luminescence systems were evaluated based on photo decay studies in order to understand the energy transfer processes in the mixed-metal system. An energy transfer from Tb to Eu was evident based on the data. Chapter 4 focuses on a 3d-4f heterometallic system based on Ni(II) that has been synthesized using a metalloligand approach. A metalloligand containing Ni was first synthesized and then used for further lanthanide coordination. The result of this effort was a bi-porous metal-organic framework (MOF) which contains both hydrophilic and hydrophobic pores. The magnetic studies showed weak antiferromagnetic interactions between the Ni centers and confirmed the absence of single-molecule magnet behavior. Chapter 5 explores another 3d-4f heterometallic system which contains Co(II) using a different synthetic approach than that reported in Chapter 4. A 2-D layer type MOF containing both Ln(III) (Ln= Pr, La, Nd) Co(II) was obtained with the use of iminodiacetic acid as the supporting ligand under solvothermal conditions which further extends to a 3-D network with extensive hydrogen bonding. Magnetic studies were carried out to explore the magnetic interactions between the metal ions and results were not conclusive due to the complicated intrinsic magnetic characteristics possessed by both Ln(III) and Co(II).Chapter 6 describes results on another lanthanide-containing MOF that assembles as a layered material creating channels between the layers. The structural analysis of the MOF of interest and other MOFs obtained under the controlled conditions were discussed. This work has potential applications as an advanced material for proton conductivity, intercalation, and ion exchange. Chapter 7 summarizes the body of work by examining the results and significance of the results presented in Chapters 2-6 and discusses the future directions possible for each project. Appendix A provides all the crystallographic information including bond lengths and angles.

The advent of transition metal catalysis has greatly expanded the scope of viable cycloaddition reactions, allowing for the direct synthesis of highly functionalized and complex biologically active compounds. By manipulating various aspects of catalyst structure, including the supporting ligands and the central metal, the function of a catalyst can be modified. In this context, the catalytic properties of dinuclear complexes have not been greatly explored in cycloaddition reactions. Our research has focused on studying the catalytic properties of dinuclear complexes in cycloaddition reactions. Comparative studies between dinuclear and mononuclear Ni-complexes led us to discover and develop an efficient route to synthesize 1,2,4-trisubstituted benzene derivatives from terminal alkynes. The key organometallic intermediates in this process were isolated, and computational studies were performed to unravel a novel bimetallic mechanism for alkyne cyclotrimerizations. As an extension of this study, we have found that the dinuclear catalyst is capable of catalyzing the methylenecyclopropanation of olefins. The reaction uses 1,1-dichloroalkene as a vinylidene precursor along with Zn as a stoichiometric reductant. A wide range of monosubstituted terminal alkenes and relatively unhindered internal alkenes are viable substrates. Furthermore, to understand the mechanism of vinylidene transfer, various stoichiometric and stereochemical experiments were performed. Furthermore, we discovered that mononuclear and dinuclear Ni-complexes are highly efficient in achieving vinylidene insertions into Si–H bonds to synthesize Si-containing heterocyclic molecules. Ongoing efforts are directed toward optimizing the reaction conditions and elucidating the substrate scope of the reaction.

[pt] A energia nuclear no Brasil tem uma longa e rica história, que inclui complexos acordos comerciais internacionais, domínio tecnológico, segredos militares e um grande acidente radiológico. Entretanto, ela é pouco estudada por nossa Geografia, que poderia ampliar o debate sobre o tema para além das tradicionais perspectivas técnico-econômicas. Neste estudo tomamos como base a teoria relacional do lugar, a tipologia das paisagens energéticas e o conceito de nuclearidade para narrar as transformações socioespaciais ocorridas a partir da instalação da Central Nuclear em Angra dos Reis, bem como as conexões desse empreendimento com o ciclo do combustível nuclear. Utilizamos múltiplas metodologias, que incluem: análise documental; entrevistas semiestruturadas com especialistas; análise de séries históricas de imagens, incluindo a aplicação de técnicas de Sensoriamento Remoto e Geoprocessamento; e trabalho de campo exploratório e confirmatório. Apresentamos os marcos iniciais na localização de reatores nucleares pelo mundo, para contextualizar os estudos realizados no Brasil que levaram à escolha da Praia de Itaorna, Angra dos Reis (RJ), para receber a primeira central nuclear do país. Essa escolha tornou Itaorna um lugar nuclear. A instalação da Central Nuclear em 1970 e sua expansão lenta e descontínua nas cinco décadas seguintes levou à uma série de alterações na composição do lugar e no seu grau de nuclearidade. Durante esse período o domínio do significado se manteve estável, enquanto os domínios da natureza e das relações sociais tiveram mudanças significativas, indicando transformações na paisagem. Estas devem ser entendidas dentro de um contexto mais amplo de transformações socioespaciais no município de Angra dos Reis, que inclui a ascensão (terminal de petróleo e Central Nuclear) e o declínio (matas carvoeiras) de paisagens energéticas. A Central Nuclear tornouse um marco na paisagem, modificou a linha de costa e criou uma área de exclusão que permitiu, em certa medida, a regeneração da vegetação no seu entorno. Por outro lado, estimulou o crescimento de um núcleo populacional em Mambucaba que reduziu a vegetação por lá. A paisagem energética da Central Nuclear é caracterizada por sua alta densidade energética, por sua dominância espacial e permanência temporal. A instalação da Central Nuclear ocorreu simultaneamente às instalações da Fábrica de Combustível Nuclear (Resende – RJ) e do Complexo Mínero-industrial do Planalto de Poços de Caldas (Caldas – MG). Esses três lugares se conectam por meio do ciclo do combustível nuclear e sua existência depende de fluxos de materiais (principalmente urânio), de pessoas e de recursos financeiros, que se estabelecem (ou se estabeleciam) entre eles. Essa interdependência diferencia as paisagens energéticas nucleares de outras, como aquelas formadas por hidrelétricas ou parques eólicos. As três paisagens nucleares possuem alta densidade energética. Dentre elas, o Complexo Mínero-industrial é responsável pela transformação mais profunda, maior dominância espacial e permanência temporal, enquanto a Fábrica de Combustível situa-se no outro extremo. A teoria relacional do lugar, a tipologia das paisagens energéticas, e o conceito de nuclearidade se revelaram uma base teórica robusta para o estudo das transformações socioespaciais no ciclo do combustível nuclear e constituem ferramentas promissoras para aplicação no planejamento energético. / [en] Nuclear power in Brazil has a long and rich history, including complex international trade agreements, technological dominance, military secrets, and a major radiological accident. However, it has received little attention from Brazilian Geography, which could broaden the debate on the subject beyond the traditional technical-economic perspectives. We applied the relational theory of place, the typology of energy landscapes, and the concept of nuclearity to describe the sociospatial transformations that occurred after the establishment of the Nuclear Power Station in Angra dos Reis, as well as the connections of this enterprise with the nuclear fuel cycle. We used mixed methods that include: document analysis; semistructured interviews with experts; analysis of historical series of images, including the application of Remote Sensing and Geoprocessing techniques; and exploratory and confirmatory fieldwork. We presented the initial milestones in the siting of nuclear reactors around the world, to put in context Brazilian studies that led to the selection of Praia de Itaorna, Angra dos Reis (RJ), to receive the first nuclear power plant in the country. This choice made Itaorna a nuclear place. The installation of the Nuclear Power Station in 1970 and its slow and discontinuous expansion over the next five decades led to a series of alterations in the composition of the place and in its degree of nuclearity. During this period, the domain of meaning remained stable, while the domains of nature and social relations had significant changes, indicating landscape transformations. These must be understood within a broader context of socio-spatial transformations in the municipality of Angra dos Reis, which includes the rise (petroleum terminal and Nuclear Power Station) and fall (charcoal forests) of energy landscapes. The Nuclear Power Station became a landmark, modified the coastline, and created an exclusion area that allowed, to a certain extent, the regeneration of the surrounding vegetation. On the other hand, it stimulated the growth of a population center in Mambucaba that reduced the vegetation there. The energy landscape of the Nuclear Power Station is characterized by high energy density, spatial dominance, and temporal permanence. The establishment of the Nuclear Power Station took place simultaneously with the establishment of the Nuclear Fuel Factory (Resende – RJ) and the Planalto de Poços de Caldas Mining Plant (Caldas – MG). These three places are connected through the nuclear fuel cycle and their existence depends on flows of materials (mainly uranium), people and financial resources, which are (or were) established between them. This interdependence differentiates nuclear energy landscapes from others, such as those formed by hydroelectric plants or wind farms. The three nuclear landscapes have high energy density. Among them, the Mining Plant causes the deepest transformation, has greater spatial dominance and temporal permanence, while the Fuel Factory is located at the other extreme. The relational theory of place, the typology of energy landscapes, and the concept of nuclearity proved to be a robust theoretical basis for the study of socio-spatial transformations in the nuclear fuel cycle and constitute promising tools to be applied to energy planning.

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