Browsing by Author "Sudowe, Ralf, advisor"
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Item Open Access Effect of matrix constituents on the determination of plutonium and americium in bone(Colorado State University. Libraries, 2019) Nguyen, Nhung Thi Nho, author; Sudowe, Ralf, advisor; Johnson, Thomas, committee member; Borch, Thomas, committee memberThere are numerous methods available in the literature for separating and analyzing radionuclides of interest from an array of environmental matrices. The quality of these methods can be affected by the stable elements that are commonly found in many of these samples. The presence of such interfering constituents can result in incomplete separation of the radioisotopes of interest as well as a reduced rate of recovery. This is especially the case when complex matrices such as samples of bone and bone ash are analyzed. Plutonium and americium tend to concentrate in bone, they are therefore often referred to as bone seekers. They accumulate in actively metabolizing portions of bones of mammals including humans. It is therefore extremely important to study and evaluate the accumulation of these radionuclides in human bone by analyzing bone samples. However, calcium, which is present in high concentrations in the hydroxyapatite that constitutes the bone, as well as sodium and potassium, have the potential to strongly affect the efficacy of radiochemical separation methods. The objective of this research is to investigate the influence of the major and minor elemental constituents present in bone on the affinity of plutonium and americium for a variety of commercial extraction chromatographic resins.Item Open Access Effects of major inorganic constituents of asphalt on the rapid determination of plutonium(Colorado State University. Libraries, 2024) Chunko, Raissa, author; Sudowe, Ralf, advisor; Brandl, Alexander, committee member; Quackenbush, Sandra, committee memberIn case of a nuclear incident, standard radioanalytical techniques must be available to analyze radionuclides in unusual matrices. Radiochemical analysis of samples in standard matrices of soil, water, and air are very well established; however, much less research has been conducted on the effect of unusual matrices such as steel, concrete, glass, and asphalt. In the event of a detonation of an improvised nuclear device (IND) in an urban environment, the standard separation techniques used for plutonium separations from asphalt samples originating from roadways and roofing shingles must rigorously be tested to provide useful insight on the characteristics of the special nuclear material. Batch studies were used to determine the changes in uptake of plutonium on extraction chromatography resins in the presence of trace metal components found in asphalt including aluminum, iron, and manganese at possible ranges found in asphalt samples. In these studies, selected cations with a +3-oxidation state had some interesting effects on the uptake of plutonium on the extraction chromatography resins. Aluminum increased the sorption of plutonium only on DGA and TRU resins especially at rising concentrations. Iron very unexpectedly increased the sorption of plutonium on all resins particularly at high concentrations. Additionally, metals found in the +3 oxidation state were shown to interfere with the recovery of plutonium from column studies conducted due to the synergistic effects. From this data, the contaminates found in asphalt with a +3-oxidation state may either compete with plutonium or give rise to a "salting out" effect that increases the sorption on the extraction chromatography resins and will need to be considered during the development of a rapid separation technique for plutonium from asphalt samples.Item Open Access Evaluation of sodium bismuthate chromatographic systems for the separation of americium from curium(Colorado State University. Libraries, 2023) Labb, Samantha A., author; Sudowe, Ralf, advisor; Brandl, Alexander, committee member; Johnson, Thomas, committee member; Henry, Charles, committee memberThe development of a successful and efficient americium (Am) and curium (Cm) separation method is necessary for stockpile stewardship science and for the simplification and improvement of currently proposed reprocessing schemes towards the closure of the nuclear fuel cycle. However, the similar chemical properties of these radionuclides (e.g., similar ionic radii, ionic bonding, and predominant trivalent oxidation states in acidic media) makes this difficult to achieve. Differences in redox chemistry can be exploited based on the fact that Am can be oxidized to higher oxidation states in acidic media while Cm cannot. Recently, the ability of solid sodium bismuthate to oxidize Am and its ion exchange properties were demonstrated in solvent extraction and chromatographic systems, but were limited by oxidation stability, kinetics, and flow rates. This dissertation focuses on evaluating and characterizing new solid-liquid chromatographic systems that combine both the oxidation and ion exchange mechanisms into one material for a continuous separation process. In addition, the solution behavior of NaBiO3 in nitric acid and the effect on acidity and dissolution kinetics is determined.Item Open Access Investigation of storage-phosphor autoradiography for alpha emitters on different types of filters(Colorado State University. Libraries, 2019) Sorcic, Ashley, author; Sudowe, Ralf, advisor; Brandl, Alexander, committee member; Omur-Ozbek, Pinar, committee memberNumerous incidents in the past have resulted in the release of radioactive contamination into the environment, some of which require continuous monitoring decades later. Past and potential future incidents encourage governments and regulating agencies to develop procedures and methods to deal with nuclear emergencies, decontamination and decommissioning, and historical preservation in the face of a possibly dangerous environment. One technique which may assist in forensics and clean-up efforts is digital autoradiography. Digital autoradiography is based on the creation of luminescence due to the interaction of ionizing radiation with the storage phosphor. The resulting image can provide information about the amount and spatial distribution of the radioactivity in a sample. While the technique is typically used for the imaging of beta-emitting radionuclides, it can also be used for alpha emitters. Previous work has shown a correlation between the radioactivity of the sample and the intensity of the light emitted by the phosphor. In addition, it was observed that the luminosity varied for different alpha emitting isotopes. The current work extended this research to other alpha emitting isotopes and the effect of the energy of the emitted alpha particle on the response of the phosphor screens. In addition the effect of different types of air filters as source material was investigated, as well as the response of Multi-Sensitive storage phosphor screens compared to SuperResolution screens. The last major variable considered was how wrinkled the filters were; this variable was first considered shortly after the sample preparations were complete.Item Open Access Investigation of the bioavailability of radiocesium in the Fukushima exclusion zone using a sequential extraction technique(Colorado State University. Libraries, 2019) McNabb, Ian, author; Sudowe, Ralf, advisor; Johnson, Thomas, committee member; Borch, Thomas, committee memberThe nuclear reactor accident at the Fukushima Daiichi power plant in March of 2011, resulted in the release of large quantities of various radionuclides into the environment. The main radionuclide of concern still remaining today is cesium-137 due to its 30-year half-life. Several areas in the vicinity of the power plant are still considered an exclusion zone owing to contamination with radiocesium, and they have not been cleared for human resettlement. While these parts are not suitable for permanent habitation, they are accessible for field work. The purpose of this research was to analyze the movement and bioavailability of radiocesium in the ecosystems contaminated by fallout from the Fukushima Daiichi nuclear reactor accident. This was achieved by analyzing soil cores collected from within the exclusion zone. The core samples were run though a 5-step sequential extraction technique, which exposes the soils stepwise to an increasingly aggressive chemical treatment. Each step targets a specific soil host phase: exchangeable, carbonate bound, Fe/Mn bound, organic, and residual. The results of this extraction yielded the following distribution of Cs-137 activity (percent of total): 0% exchangeable, 1-16% carbonate bound, 0-5% Fe/Mn bound, 1-5% organic, 44-67% residual, and 25-47% non-extracted. These results show that most of the Cs-137 is irreversibly bound to clays in the soil. However there are differences between soil sampling sites in regards to the amount of Cs-137 successfully extracted in the carbonate bound, Fe/Mn bound, and Organic fraction, which provides evidence that Cs-137 mobility and bioavailability is partly dependent on local soil mineralogy and chemistry.Item Open Access Investigation of the extraction of stable ⁴⁵Sc and carrier free ⁴⁴Sc for theranostic applications(Colorado State University. Libraries, 2022) Brown, Morgan L., author; Sudowe, Ralf, advisor; Brandl, Alexander, committee member; Zadrozny, Joseph, committee memberScandium is an element of major interest when it comes to theranostic applications. There are mainly two isotopes of scandium utilized in medical applications, Sc-44 and Sc-47. Sc-44 is a positron emitter and is used for imaging, while Sc-47 is utilized as a beta emitter for targeting tumors. Together, the pair make up a theranostic agent. This research mainly focuses on Sc-44. To utilize the isotope after production, it must first be separated and purified from target material, in this case titanium. One of the quickest and most efficient way to separate radioisotopes, especially for medical purposes, is extraction chromatography. The goal of this research is to understand and possibly improve the separation of scandium from titanium by employing a variety of different chromatographic resins in a fast manner. Previous studies in the literature yielded data from several groups that examined the uptake of scandium and titanium on an extraction chromatographic resin based on a tetraoctyl diglycolamide, DGA. These groups employed either stable or radioactive scandium for their experiments. While the uptake of titanium was consistent between the studies, all groups have reported different values for the uptake of scandium. The aim of this part of the work is to compare both the uptake of stable and radioactive scandium to further elucidate the discrepancies between the studies reported in the literature. Radioactive Sc-44 for tracer studies will be obtained by "milking" a Ti-44 generator in regular intervals. Both stable and radioactive results obtained in this research will be compared.Item Open Access Optimization and comparison of radioanalytical methods for the determination of radium and other alpha-emitting radionuclides in process water samples from the oil & gas industry(Colorado State University. Libraries, 2022) Coupannec, Maelle, author; Sudowe, Ralf, advisor; Brandl, Alexender, committee member; Johnson, Thomas, committee member; Borch, Thomas, committee memberA major concern arising from hydraulic fracturing is the generation of a large volume of flowback water potentially containing various amounts of dissolved Naturally Occurring Radioactive Material (NORM). Up to four million gallons of water-based fluid is injected per well, of which 10–70% is subsequently recovered as flowback. Improving the separation and measurement of "Technologically Enhanced Naturally-Occurring Radioactive Material" (TENORM) is a priority in efficiently determining the amount of radionuclides present. An accurate assessment of radium concentration in flowback water is needed to understand potential environmental contamination from hydraulic fracturing sites and bodies of water affected by the mining industry. A significant scientific challenge in radium determination in flowback water is the presence of chemical analogues, calcium, barium, and strontium, in the flowback and produce water. Thus, the development of an accurate radium measurement and separation process is an essential step for appropriate disposal of the flowback water as regulated or non-regulated NORM-containing wastes. Non-destructive analysis of radium using direct gamma spectrometry measurements was performed on flowback water and provided accurate quantities. However, the long counting time necessary to achieve the detection limits renders the analysis impractical. Several approaches to improving radium separation and measurement methods are explored in this work. Pre-conconcentration of radium with barium sulfates was investigated to provide a more rapid gamma screening. The use of Actinide resin instead of TRU resin for column separations was studied as a means to preconcentrate Th, U, and Po in flowback and produced water from the oil and gas industry. The use of an actinide resin is expected to improve the recently developed EPA method for alpha and beta dual analysis for a complete Ra, Th, U, and Po screening or flowback water. Complete separation of radium from the wastewater matrix is ideal and will provide faster radium analysis, reducing the costs associated with handling, treatment, and disposal of wastewater. Multiple proprietary extraction chromatographic resins developed by TrisKem Int. (Bruz, France) were investigated as a function of nitric acid concentration to quantify and enhance the separation of radium from its chemical analogues. Separation of strontium from the resin matrix could easily be achieved using TKI, Sr, or Pb resin as large separation factors were obtained. The TK101 resin is promising for achieving the more difficult separation of barium from radium as the separation factor was found to be 4.3 at 0.04 M HNO3.Item Open Access Radiation doses around the Fukushima Dai-Ichi Nuclear Power Plant: measurements and novel methods of analysis(Colorado State University. Libraries, 2018) Seel, Peter James, author; Sudowe, Ralf, advisor; Brandl, Alexander, committee member; Miller, Charles W., committee memberThe nuclear accident which occurred at the Fukushima Dai-Ichi Nuclear Power Plant in March of 2011 released an estimated 940 petabecquerels (PBq) of I-131 equivalent radioactive emissions, of which over 32 PBq were the longer-lived isotopes Cesium-134 and Cesium-137 (Half-lives: 2.06 years, and 30.01 years). Accurate means and methods of tracking the dose rates resulting from the deposition of these two isotopes are critical to understanding when former residents can move back into the area and the remaining potential health risks. Remote sensing stations, vehicle surveys, and airborne surveys were all analyzed and compared for their efficacy and utility in dose rate tracking. Remote stations were found to be useful for long-term temporal trends, but lack validity in generalizing beyond the immediate area of each site. Analysis of data provided by these stations showed a statistically significant drop in dose rate below that expected from radioactive decay alone. This implies that radioisotopes are moving out of the vicinity of stations, likely through environmental means. Vehicle surveys provide a middle ground of spatial resolution and frequency of data collection, and dose correction factor of 1.31 from car dose rate to ambient dose equivalent rate was modeled based on conducted vehicle surveys for field use by non-experts. Utilizing GIS analytical techniques, elevation and slope were found to be statistically influential factors in dose rate changes. Importantly, different types of environments were stratified and compared to show the relative loss of radiation within them, confirming that most forests retain radioisotopes more than the median level for the region, while urban area and bare land dose rates decrease more quickly. The GIS methods tested will be useful in analyzing further surveys results and could be used to plan future research and compare to other measurement types.Item Open Access Radiocesium fate and transport in the soil-water environment in the proximity of the Fukushima Dai-Ichi Nuclear Power Plant(Colorado State University. Libraries, 2020) Udy, Cameron, author; Johnson, Thomas, advisor; Sudowe, Ralf, advisor; Borch, Thomas, committee memberThe objective of this research was to examine the dynamics of Cs-134 and Cs-137 in the aquatic ecosystems of the contaminated areas adjacent to the Fukushima Dai-ichi Nuclear Power Plant (FDNPP). Samples of water, suspended and bottom sediments from rivers, ponds, and a reservoir were collected. Three rivers (Niida, Abukuma, and Maeda), four ponds (Inkyozaka, Suzuuchi, and Funasawa 1& 2), and Sakashita Reservoir located in the Fukushima contaminated area were the focus of the study. Bottom sediment cores were taken from the Sakashita reservoir to analyze vertical distribution of radiocesium (r-Cs). Water samples were collected and filtered using an in-situ filtration system in the field or by using a laboratory filtration system. Dissolved Cs-134 and Cs-137 were removed from water using one of two different sorbents, a cartridge with non-woven cloth impregnated with potassium zinc ferrocyanide or a column filled with granulated cellulose impregnated with Iron Ferrocyanide. Activity concentrations of Cs-134 and Cs-137 were measured via gamma-spectrometry on a high purity Germanium detector, and concentrations of major cations affecting r-Cs behavior were measured via Ion Chromatography and Inductively Coupled Plasma Mass Spectrometry (ICP/MS). R-Cs was concentrated in the sediment in all but two of the river samples. Suzuuchi pond r-Cs was primarily concentrated in the sediment in both samples, but in the other three ponds r-Cs switched between being primarily concentrated in suspended sediment in July from being primarily dissolved in solution during June. Sakashita reservoir r-Cs was primarily dissolved in solution. Mean river Kd values (L/g) were five to ten times higher than the mean values from the ponds and reservoir. River Kd variance was also much higher due to three river sample points having Kd values over 1000 while the rest were below 500.Item Open Access Study of hexacyanoferrate(II) nanodiamond adsorbent for the preconcentration of cesium and size categorization of radiocesium particles from contaminated soil(Colorado State University. Libraries, 2021) Deak, Anna, author; Sudowe, Ralf, advisor; Johnson, Thomas, committee member; Borch, Thomas, committee memberHigh levels of radioactive cesium (RCs) were released into the environment as a result of the Fukushima Dai-ichi Nuclear Power Plant accident in March 2011. Wide areas, including residential and farming spaces, were contaminated to varying degrees with 134Cs and 137Cs which has presented complications with soil and water utilization for personal use. The current decontamination efforts used to remove RCs from the topsoil have been costly and created new challenges in storing low-level radioactive waste. Meanwhile, determining low levels of radioactivity in the environment is a challenge in itself, since changes in sample composition and self-shielding coupled with the sample amount required to meet low minimum detection limits lead to inaccurate measurements. This project investigates the use of a hexacyanoferrate(II) nanodiamond adsorbent to preconcentrate dissolved Cs in contaminated solutions in order to improve the counting efficiency and accuracy for low activity samples. Also, the determination of the size of particle attached radiocesium from previous soil samples that have undergone sequential extraction was attempted in order to study how particle size affects migration and deposition behavior. The majority of the preconcentration studies yielded over 98% 137Cs adsorption. Further investigation into preconcentration studies is recommended to test adsorbent performance in more dynamic conditions. Meanwhile, activity measurement of 0.45 μm, 0.2 μm, and 0.1 μm filters for Cs-137 indicated that the vast majority of the extracted RCs in the fractions obtained by sequential extraction was in a dissolved form. Therefore, the RCs that was extracted from the soil is not present in the form of microparticles with an activity greater than 5 Bq. This research was supported by grant T42OH009229 funded by the National Institute for Occupational Safety and Health (NIOSH) from the Centers for Disease Control and Prevention (CDC). No known conflict of interest exists within this study.