Understanding the transport and retention of radionuclides in the environment is important for protecting freshwater supplies and minimizing impact to biologic systems. Technetium-99 (Tc⁹⁹) is a radionuclide of interest due to its long half-life (2.13 x 10⁵ years) and toxicity. In the form of pertechnetate (TcO₄⁻), Tc is expected to move nearly unretarded in the subsurface. Under reducing conditions Tc can precipitate in low solubility Tc oxide (TcO₂·nH₂O) and/or Tc sulfide (Tc₂S[subscript x]) phases. The studies presented in this dissertation investigate the physiochemical mechanisms for the transport and retention of Tc. Transport studies determined that TcO₄⁻ would move at pore water velocity in unsaturated sediments. Geochemical studies of contaminated sediments determined that nearly ~ 25 % of the total Tc was retained in phases associated with iron oxide and aluminosilicate minerals, thus reducing the mobility of Tc. Studies of Tc₂S[subscript x] mineral phases, generated using nano Zero Valent Iron (nZVI) and sulfide (HS-) in sediments, determined that Tc could be stabilized in mineral phases as Tc₂S[subscript x] that were slower to reoxidize than TcO₂·nH₂O phases. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from Feb. 14, 2013 - Feb. 14, 2014

Made available in DSpace on 2014-10-09T12:42:17Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:03Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:42:17Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:03Z (GMT). No. of bitstreams: 0 / O uso das amostragens ambientais para fins de salvaguardas vêm sendo aplicadas pela Agência Internacional de Energia Atômica AIEA desde 1996 e estão sendo rotineiramente utilizadas como uma medida de fortalecimento complementar aos procedimentos tradicionais de salvaguardas de materiais nucleares. O intuito é verificar se os Estados signatários aos acordos de salvaguardas não estão divergindo suas atividades nucleares pacíficas para atividades nucleares não declaradas. O presente trabalho apresenta um novo protocolo de coleta e análise de esfregaços para identificação de assinaturas nucleares que possam relacionar-se com as atividades nucleares desenvolvidas na instalação inspecionada. Neste trabalho foi utilizada como estudo de caso uma planta real de reconversão de urânio do ciclo do combustível nuclear do IPEN. A estratégia analítica proposta utiliza diferentes técnicas, como medidor de radiação alfa, MEVEDS e ICPMS para identificar assinaturas do urânio aderido ao esfregaço. Na análise dos esfregaços, foi possível identificar partículas de UO2F2 e UF4 através da comparação morfológica e análises semi-quantitativas utilizando a técnica de MEVEDS. Nesse trabalho, utilizaram-se métodos que como resultado tem-se a composição isotópica média da amostra, onde o enriquecimento (fração atômica molar) variou de 1,453 ± 0,023% a 18,24 ± 0,15% no isótopo 235U. Através das coletas realizadas externamente, uma forma não intrusiva de amostragem, foi possível à identificação de atividades de manuseio de material enriquecido com medidas de fração atômica molar de 1,453 ± 0,023% a 6,331 ± 0,055% no isótopo 235U, bem como uso de material reprocessado, através da identificação do isótopo 236U. As incertezas obtidas neste trabalho para a razão n(235U)/n(238U) variaram de 0,40% a 1,68%. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

To illustrate the intersection of ethical language and ethical frameworks within technical communication, this dissertation analyzes the history and documentation of the human radiation experiments of the 1940s through the 1970s. Research propositions included clarifying the link between medical documentation and technical communication by reviewing the literature that links the two disciplines from the ancient period to the present; establishing an appropriate historiography for the human radiation experiments by providing a context of the military, political, medical, and rhetorical milieu of the 1940s to the 1970s; closely examining and analyzing actual human radiation experiment documentation, including proposals, letters, memos, and consent forms, looking for established rhetorical constructions that indicate a document adheres to or diverts from specific ethical frameworks; and suggesting the importance of the human radiation documents for studying ethics in technical communication. Close rhetorical analysis of the documents included with this project reveals consistent patterns of metadiscourse, passive and nominal writing styles, and other rhetorical constructions, including negative language, redundancies, hedges, and intensifiers, that could lead a reader to misunderstand the writer's original ethical purpose. Ultimately this project finds that technical communicators cannot classify language itself as ethical or unethical; the language is simply the framework with which the experimenters construct their arguments and communicate their work. Technical communicators can, however, consider the ethical nature of behavior according to specific ethical frameworks and determine whether language contributes to the behavior.

Thesis (Ph.D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2002. / Includes bibliographical references. / This thesis addresses the sources and transport of nuclear weapons related contamination in the Ob River region, Siberia. In addition to being one of the largest rivers flowing into the Arctic Ocean, the bulk of the former Soviet Union's nuclear fuel reprocessing and weapons testing facilities (i.e. Mayak, Tomsk-7, and Semipalitinsk) are located within the Ob drainage basin. The atom ratios 240Pu/239Pu, 237Np/239Pu, and 137Cs/240Pu, measured by magnetic-sector ICP-MS, are used to distinguish between contamination derived from global fallout and contamination derived from local sources. Deposition chronologies estimated for sediment cores are used to construct a record of weapons related contamination at the sites sampled. Contaminant records indicate that in addition to debris from atmospheric weapons tests, materials derived from local sources have also played a role in nuclear weapons related contamination of the Ob region. Isotopic data presented in this study clearly demonstrate that non-fallout contamination has been transported the full length of the Tobol, Irtysh, and Ob Rivers (i.e. the tributaries draining Mayak, Semipalitinsk, and Tomsk-7, respectively). In several instances, unique isotopic compositions are observed in sediments collected from tributaries draining each of the suspected non-fallout sources. In such cases, these materials and their deposition ages have been used to link contamination in the Ob delta to Mayak, Tomsk-7, or Semipalitinsk. Linear transport rate estimates (km yr-1) indicate that contaminated sediments transit between source tributaries and the Ob delta on time-scales of [less than or equal to] l year. / (cont.) These estimates suggest that a catastrophic release of contamination due to dam failure at one of the many reservoirs located at both Mayak and Tomsk-7 that contain high levels of radioactive waste would result in measurable levels of contamination in the delta within as little as 1 year. Isotopic concentrations in sequentially extracted sediments containing weapons related contamination reveal that the majority of plutonium and neptunium (80 to 90 percent) behaves in a similar fashion regardless of the source and is removed by treating the sediments with citrate-dithionite. This indicates that plutonium and neptunium are not truly refractory and likely associate with redox sensitive sedimentary components. Isotopic ratios measured in extracted fractions suggest that only a minor fraction of contamination is associated with acid leachable or acid digestible sedimentary phases. / by Timothy Cope Kenna. / Ph.D.

Concentration ratios are used to determine the transfer of nuclides from soil to biota to fauna. Some nuclides have limited associated data though, this has not prevented predictions from being performed at sites without associated data. These ratios are site specific and are not fully applicable when applied to other locations. A recent literature review for a waste repository performance assessment determined that a significant portion of the environmental data was based on recursively published material. To address this deficiency neutron activation analysis (NAA) was used to determine concentration ratios of certain biota. Three sites, two riparian and one shrub steppe, were sampled in the eastern Washington Columbia basin, near the Hanford site. Two hundred and fifty eight samples of opportunity were collected. This included 15 soil samples, 10 water and sediment samples, 40 different species of biota, and 2 terrestrial animal species and 3 aquatic animal species. These samples were prepared for NAA by drying, weighing, and in certain cases ashing to improve detection efficiency. After activation, the samples were placed in a HPGe detector to perform spectral analysis. The concentration results of 26 elements of interest are presented, along with newly established concentration ratios for all of the species sampled. / Graduation date: 2013