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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.

Thesis (Ph. D.)--University of Queensland, 2001. / Includes bibliographical references.

How people perceive risk or threats is important to many disciplines that seek to assist policy makers in developing policies, regulations and laws. Using the previous work of Slovic et al. (Fischhoff, Slovic, Lichtenstein, Read and Combs, 2000; Slovic P., 1992; Slovic, Fischhoff, and Lichtenstein, 2000) in development of the psychometric paradigm, a sample of residents (n=600) from a region with a large number of nuclear reactors was surveyed. The question set was expanded to include demographic questions to determine if they impact risk perception. Two aspects of risk perception were examined, perception of overall risk and perception of riskiness along specific dimensions of concern identified previously in the literature. For both risk and riskiness, respondents’ perceptions of nuclear power were compared to three other perceptions of technologies including use of modern farming methods using chemicals, railroad transportation and coal-generated electricity. The recent increase in public concern about nuclear power following the meltdowns at the Fukushima Dai-ichi nuclear power plant led to the expectation that nuclear power would be rated higher in overall risk and riskiness than the other three technologies consistent with Slovic’s earlier work on risk perception. This expectation was generally supported although respondents tended to perceive modern farming methods using chemical as similar in overall risk and riskiness to nuclear power. The research specifically tested five hypotheses concerning the impact of five demographic factors: gender, race, income, education and political orientation on the overall perception of risk and riskiness. Subsequent analysis using analysis of variance and linear regression found that select demographics only explained 2% of the risk perception for nuclear power generation.

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Magister Legum - LLM / African states are interested in the development of nuclear power (also referred to as atomic power) for the generation of electricity and desalination. These include Algeria, Egypt, Ghana, Kenya, Morocco, Namibia, Niger, Nigeria, Tunisia, South Africa, and Uganda. The nuclear governance in South Africa has adopted principles into its legal system which require it to comply with the objectives of numerous resolutions, conventions, treaties, bilateral and multilateral agreements. Therefore, there is an obligation upon the government through ‘reasonable legislative and other measures’ to manage nuclear matters, such as nuclear accidents, in a manner that protects the general public, atomic industry workers as well as prevents the pollution of the surrounding environment. It has been seven years since the Fukushima Daiichi Nuclear Power Plant Accident that occurred in Japan on 11 March 2011, when considerable amounts of radioactive material from the damaged plant released into the environment. Health hazards, associated with exposure to low levels of ionising radiation, are a significant concern following such an accident. A nuclear disaster can potentially violate not only the right to health of workers, but that of residents and evacuees alike, particularly pregnant women, older persons, and children. Regional and international human rights conventions impose obligations on state parties to “take whatever steps necessary to ensure that the right to the highest attainable standard of health is enjoyed by all as soon as possible”. In most cases, when a nuclear accident occurs, workers within the nuclear plant are expected to mitigate emergencies. The danger of this expectation is that it could violate their fundamental human rights.

Este trabalho teve por objetivo o desenvolvimento de uma metodologia de análise estrutural de heteroestruturas, ou seja, estruturas formadas pela combinação de materiais diferentes depositados em camadas alternadas. O trabalho focalizou aspectos não apenas referentes às técnicas de difração de raios X, comumente utilizadas na caracterização estrutural destes novos materiais, mas também se concentrou no desenvolvimento de cálculos teóricos da intensidade difratada pelos raios X, os quais, comparados com os dados experimentais, dão informação precisa acerca do que poderíamos denominar qualidade estrutural. Uma comparação entre resultados obtidos com a teoria Cinemática Dinâmica foram também explorados e o alcance das duas teorias foi discutido. Este procedimento, embora tenha sido aplicado para a análise de heteroestruturas a base de semicondutores cristalinos, pode também ser aplicado, por exemplo, ao estudo de heteroestruturas magnéticas. É sempre fundamental no processo de desenvolvimento de novos materiais caracterizar as amostras após o crescimento, a fim de comparar os resultados experimentais com os valores nominais obtidos do procedimento de deposição. Em particular, neste trabalho, a caracterização estrutural de super-redes deformadas de Si 1-xGex/Ge e Si/Ge, crescidas sobre substratos de Ge e Si, respectivamente, realizou-se através do uso de técnicas não destrutivas de difração de raios X, envolvendo a medição dos parâmetros próprios das super-redes como: período, número de camadas atômicas, parâmetros de rede e deformação. / The aim of this work was the development of a methodology for the structural analysis of heterostructures, i. e., structures formed by the combination of different materials, deposited as alternate layers. The work focused on aspects not only related to x-ray diffraction techniques, usually utilized for the structural characterization of these new materials, but also it concentrated on the development of theorical calculations of the x-ray diffracted intensity, which were compared with experimental data in order to determine the so-called structural quality. The results obtained with the Kinematical and Dinamical X-ray Diffraction theories were explored and the scope of both theories was discussed. Even though this procedure was applied to the analysis of heterostrutures based on crystalline semiconductors, it also can be used, for example, to the study of magnetic multilayers. It is always fundamental in the development process of new materials to characterize the samples after growth, in order to compare the experimental results with the nominal values obtained by the deposition procedure. ln particular, in this work, the structural characterization of Si1-xGex /Ge and Si/Ge strained superlattices, deposited on Ge and Si substrate, respectively, was performed by means of non-destructive x-ray diffraction techniques, measuring superlattices parameters as: periodicity, number of atomic layers, lattice parameters and strain.

Este trabalho teve por objetivo o desenvolvimento de uma metodologia de análise estrutural de heteroestruturas, ou seja, estruturas formadas pela combinação de materiais diferentes depositados em camadas alternadas. O trabalho focalizou aspectos não apenas referentes às técnicas de difração de raios X, comumente utilizadas na caracterização estrutural destes novos materiais, mas também se concentrou no desenvolvimento de cálculos teóricos da intensidade difratada pelos raios X, os quais, comparados com os dados experimentais, dão informação precisa acerca do que poderíamos denominar qualidade estrutural. Uma comparação entre resultados obtidos com a teoria Cinemática Dinâmica foram também explorados e o alcance das duas teorias foi discutido. Este procedimento, embora tenha sido aplicado para a análise de heteroestruturas a base de semicondutores cristalinos, pode também ser aplicado, por exemplo, ao estudo de heteroestruturas magnéticas. É sempre fundamental no processo de desenvolvimento de novos materiais caracterizar as amostras após o crescimento, a fim de comparar os resultados experimentais com os valores nominais obtidos do procedimento de deposição. Em particular, neste trabalho, a caracterização estrutural de super-redes deformadas de Si 1-xGex/Ge e Si/Ge, crescidas sobre substratos de Ge e Si, respectivamente, realizou-se através do uso de técnicas não destrutivas de difração de raios X, envolvendo a medição dos parâmetros próprios das super-redes como: período, número de camadas atômicas, parâmetros de rede e deformação. / The aim of this work was the development of a methodology for the structural analysis of heterostructures, i. e., structures formed by the combination of different materials, deposited as alternate layers. The work focused on aspects not only related to x-ray diffraction techniques, usually utilized for the structural characterization of these new materials, but also it concentrated on the development of theorical calculations of the x-ray diffracted intensity, which were compared with experimental data in order to determine the so-called structural quality. The results obtained with the Kinematical and Dinamical X-ray Diffraction theories were explored and the scope of both theories was discussed. Even though this procedure was applied to the analysis of heterostrutures based on crystalline semiconductors, it also can be used, for example, to the study of magnetic multilayers. It is always fundamental in the development process of new materials to characterize the samples after growth, in order to compare the experimental results with the nominal values obtained by the deposition procedure. ln particular, in this work, the structural characterization of Si1-xGex /Ge and Si/Ge strained superlattices, deposited on Ge and Si substrate, respectively, was performed by means of non-destructive x-ray diffraction techniques, measuring superlattices parameters as: periodicity, number of atomic layers, lattice parameters and strain.

The Safety Analysis Report (SAR) of the Oregon State University TRIGA Research Reactor (OSTR) was prepared and used as a safety baseline for the reactor's operation since 1968. Although, in general, revision of the Safety Analysis Report of a research reactor is not a regulation requirement, it should be revised from time to time to include changes to the facility or procedures or update to current regulatory standards. The ANS 15.21 workgroup developed a draft standard format and content for safety analysis reports for research reactors. An area of this guidance, which was selected for this work's revision of OSTR-SAR, is the radiation protection program and waste management chapter. The Health Physics program of the facility was observed. The radiological data were obtained from the annual reports for more than 10 years of operation. The related data, such as meteorological data, were obtained and prepared for the analysis processes. The current federal regulation limits and recommendations were used as the references for dose assessments. The results show the OSTR has a sufficient radiation protection program not only for the facility's workers, but also for the general public, and the program is in full compliance with the federal regulations. The dose estimation shows that the workers and general public can not receive and have not received doses in excess of regulatory limits from the normal operation of the OSTR. / Graduation date: 2000

The utilisation of alternate sources of energy has reached critical levels due to the constantly growing demand for energy and the diminishing of fossil fuels. The production of hydrogen through the Hybrid Sulphur process is a possible alternative that may contribute towards alleviating the pressure on the world's energy resources. The two-step thermochemical cycle for decomposing water into hydrogen and oxygen offers the potential to obtain acceptable thermal efficiencies, while still using common and inexpensive chemicals. The process mainly makes use of two unit process operations: an electrolyser and a chemical decomposition reactor. This research project focuses on the concept design of the decomposition reactor operated adiabatically as a multi-stage reactor system with inter-stage heating, in order to simplify the reactor design. This approach allows for the independent evaluation of the reaction kinetics and the heat transfer mechanism. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2009.