Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Graduation date: 1979

Thesis (M.S.)--University of Nevada, Reno, 2005. / "December 2005." Includes bibliographical references (leaves 69-72). Online version available on the World Wide Web.

Graduation date: 1966

Graduation date: 1997

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.

Stream transport is an important process in the dispersion of radioactive material that has been released by man into his environment. Some portion of the radionuclides that enter the stream system may remain in solution. However, a significant amount will become associated with aquatic organisms and sediments in the stream. The relative distribution will depend upon the particular radionuclide and the environmental factors of the stream system. Contemporary sediment samples from preselected locations in the Guadalupe River drainage basin were analyzed for their mineral composition, ion exchange capacity, and radionuclide sorption. The clay minerals were the most significant agents in the radionuclide sorption processes. X-ray diffraction patterns of the clay-sized particles show the presence of a heterogeneous mixed-layered clay mineral complex of poor crystallinity. The degraded nature of these crystallites is suggested by the low intensities and the broad and diffuse diffraction maxima. Ion exchange capacity measurements gave values of 10 to 47 meq/100 grams and projected values of 20 to 73 meq/100 grams of clay material. Radionuclide sorption studies using cesium-137 and strontium-89 were made on the naturally occurring sediments and sediments from which the organic fraction had been removed. Sorption values were compared with mineralogy and ion exchange capacity to obtain points of correlation. Rates of radionuclide sorption and release were highest during the first few moments of contact, but totals slowly continued to increase throughout the seven-day duration of the experiments. Sediments containing the naturally occurring organic fraction had the highest sorption values both for strontium-89 and cesium-137. The organic fraction contributes to the over-all sorption capacity of the sediments, even though some of the organic molecules may block exchange sites on the clay minerals against exchange with the radionuclide. These laboratory experiments indicated that radionuclide sorption in the dynamic fluvial environment was temporary. When the contaminated sediments were placed in conditions simulating a marine environment, 43 percent of the cesium-137 and 42 percent of the strontium-89 were released because of competition for the exchange sites from the more abundant ions in sea water. Even though fluvial releases are considered an acceptable means of radionuclide disposal, it should be emphasized that all stream systems are dynamic, and this disposal is at best temporary. The brief respite gained today may be overshadowed by the ultimate contamination of tomorrow. / text

The ability to map industrial discharges through remote sensing provides a powerful tool in environmental monitoring. Radionuclide effluents have been discharged, under authorization, into the Irish Sea from BNFL (British Nuclear Fuels Plc.) sites at Sellafield and Springfields since 1952. The quantitative mapping of this anthropogenic radioactivity in estuarine intertidal zones is crucial for absolute interpretations of radionuclide transport. The spatial resolutions of traditional approaches e.g. point sampling and airborne gamma surveys are insufficient to support geomorphic interpretations of the fate of radionuclides in estuaries. The research presented in this thesis develops the use of airborne remote sensing to derive high-resolution synoptic data on the distribution of anthropogenic radionuclides in the intertidal areas of the Ribble Estuary, Lancashire, UK. From multidate surface sediment samples a significant relationship was identified between the Sellafieldderived 137Cs & 241Am and clay content (r2=0.93 & 0.84 respectively). Detailed in situ, and laboratory, reflectance (0.4-2.5mn) experiments demonstrated that significant relationships exist between Airborne Thematic Mapper (ATM) simulated reflectance and intertidal sediment grain-size. The spectral influence of moisture on the reflectance characteristics of the intertidal area is also evident. This had substantial implications for the timing of airborne image acquisition. Low-tide Daedalus ATM imagery (Natural Environmental Research Council) was collected of the Ribble Estuary on May 30th 1997. Preprocessing and linear unmixing of the imagery allowed accurate sub-pixel determinations of sediment clay content distributions (r2=0.8 1). Subsequently, the established relationships between 137Cs & 241Am and sediment grain-size enabled the radionuclide activity distributions across the entire intertidal area (92km2) to be mapped at a geomorphic scale (1.75m). The accuracy of these maps was assessed by comparison with in situ samples and the results of previous radiological studies within the estuary. Finally, detailed conclusions are made regarding radionuclide sinks and sources, and surface activity redistribution within the Ribble Estuary environment.

Fault zones are potential paths for release of radioactive nuclides from radioactive-waste repositories in granitic rock. This research considers detailed maps of en echelon fault zones at two sites in southern Sweden, as a basis for analyses of how their internal geometry can influence groundwater flow and transport of radioactive nuclides. Fracture intensity within these zones is anisotropic and correlated over scales of several meters along strike, corresponding to the length and spacing of the en echelon steps. Flow modeling indicates these properties lead to correlation of zone transmissivity over similar scales. Intensity of fractures in the damage zone adjoining en echelon segments decreases exponentially with distance. These fractures are linked to en echelon segments as a hierarchical pattern of branches. Echelon steps also show a hierarchical internal structure. These traits suggest a fractal increase in the amount of pore volume that solute can access by diffusive mass transfer, with increasing distance from en echelon segments. Consequences may include tailing of solute breakthrough curves, similar to that observed in underground tracer experiments at one of the mapping sites. The implications of echelon-zone architecture are evaluated by numerical simulation of flow and solute transport in 2-D network models, including deterministic models based directly on mapping data, and a statistical model. The simulations account for advection, diffusion-controlled mixing across streamlines within fractures and at intersections, and diffusion into both stagnant branch fractures and macroscopically unfractured matrix. The simulations show that secondary fractures contribute to retardation of solute, although their net effect is sensitive to assumptions regarding heterogeneity of transmissivity and transport aperture. Detailed results provide insight into the function of secondary fractures as an immobile domain affecting mass transfer on time scales relevant to field characterization and repository safety assessment. In practical terms, secondary fractures in these en echelon zones are not indicated to limit release of radiation to the surface environment, to a degree that is significant for improving repository safety. Thus en echelon zones are to be regarded as detrimental geologic features, with potentially complex transport behavior which should be considered in the interpretation of in-situ experiments. / Graduation date: 2005

NCRP report No.160 states that medical exposure increased to nearly half of the total radiation exposure of the U.S. population from all sources in 2006 (NCRP 2009). Part of this increase in exposure is due to the rise in nuclear medicine procedures. With this observed growth in medical radionuclide usage, there is an increase in the radionuclide being released into wastewater after the medical procedures. The question then arises: what is the behavior of medical radionuclides and their impurities in the wastewater process? It is important to note that, often, medical radionuclides are not exactly 100% radionuclide pure, but they meet a certain standard of purity. Of particular interest are the longer lived impurities associated with these medical radionuclides. The longer lived impurities have a higher chance of reaching the environment. The goal of this study is to identify the behavior of medical radionuclides and their impurities associated with some of the more common radiopharmaceuticals, including Tc-99m and I-131, and locate and quantify levels of these impurities in municipal wastewater and develop a model that can be used to estimate potential dose and risk to the public. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from May 24, 2012 - May 24, 2014