Doctor of Philosophy (PhD)
Chemistry and Biochemistry
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Most current radioanalytical protocols have been developed for the analysis of air, water, soil and bioassay samples. While these protocols build the foundation of operational environmental monitoring, they are not necessarily suitable for the analysis of samples that will be encountered in the aftermath of a nuclear incident. In such a situation, it will be important to characterize the isotopes of interest present in the affected area to obtain signatures for nuclear forensics and ensure the appropriate response. Specifically, this research is aimed at the determination of strontium-90 and its separation from zirconium-90 in a post-detonation situation.
Strontium-90’s relatively long half-life (28.79(6) years) and high fission yield, along with its daughter’s high energy beta decay (90Y at 2.281 MeV) make it one of several materials ideally used in radioisotope thermoelectric generators (RTGs) in remote corners of the globe. Unfortunately, many of these RTGs remain in service with little to no security around them. Couple this with 90Sr and 90Y being pure beta emitters requiring relatively little shielding to conceal and 90Sr preferentially depositing in bones, increasing the likelihood of bone or blood cancer, when ingested or inhaled and it is easy to see why these RTGs would be appealing targets for terrorist to obtain material for a so-called “dirty bomb”. Following an attack of this nature, it will be important to quantify the total amount of strontium dispersed and to determine if this is equivalent to known missing sources or some fraction thereof, indicating the possibility of multiple attacks with smaller amounts of activity. By separating the 90Sr from its stable grand-daughter 90Zr, it also is possible to age the material originally used in the improvised device and provide insight on where it may have come from or who may have originally manufactured it.
Due to the likelihood of such a device being used in an urban or metropolitan area, it is crucial to have procedures that can be used to rapidly and accurately separate and determine radioactive materials from matrices found in these environments. Of particular interest for nuclear forensics are methods that can be applied to the analysis of concrete, steel, and glass.
Chromatographic resins have been used for radioanalytical separations for several years now, and a large amount of data has been published on the retention capabilities of many of these resins for a wide variety of elements that can be found in environmental samples. Little can be found, however, on the effect that matrix constituents present in debris samples can have on analyte uptake. This results in potentially very complex pre-concentration methods that slow the throughput of samples. If the effects of matrix constituents could be quantified, ways to streamline or, in some cases, totally eliminate these pre-concentration steps may arise. To this end, the research described here concentrates on characterizing the interference caused by various constituents of urban matrices, as well as alternative acid conditions that could be used for separations based on dissolution procedures likely to be used in a real world scenario.
Extraction Chromatography; RDD; Strontium; Urban Rubble
Analytical Chemistry | Chemistry | Radiochemistry
University of Nevada, Las Vegas
Mclain, Derek Roger, "Interference Effects of Urban Rubble on the Radioanalytical Analysis of Strontium" (2016). UNLV Theses, Dissertations, Professional Papers, and Capstones. 2883.
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