Soil that is contaminated with radioactive elements poses an exposure hazard to those whom may take up temporary or permanent residence on such a site. Of particular interest is the internal exposure from ingestion of this radioactive soil. Although most ingestion of soil is inadvertent, usually being attached to foodstuffs that are not properly cleaned, it is possible that a person might consume a larger quantity. Childhood soil ingestion from simple hand-to-mouth activities is one explanation for this larger intake, as well as geophagia (eating dirt) or pica (craving and eating non-food items). The assumption that any person might consume a "mouthful" of dirt is a rare but possible occurrence that, when analyzed, will help with decisions about safe contamination levels of soil. Samples of soils contaminated with radium-226 were sent from an engineering and environmental firm to Oregon State University's Department of Nuclear Engineering and Radiation Health Physics for assessment. The analysis of the samples was aimed at the determination of bioavailability and bioaccessibility of the radioactive species found in the soils. Subsequent site remediation actions for the New Jersey-based project would be partially dictated by the results of Oregon State University's testing. Initially, the soils were tested for the presence of carbonates, for leachability of radioactivity in water and in acid, and for particle size distribution, i.e., soil type. Each of the eight samples was then subjected to a stomach/intestinal analogue to determine how much of the radioactivity would be transferred to solution upon human ingestion, (bioaccessibility). Mass balance and gamma spectrometry outputs for the soil samples before and after the digestion was one way the loss to solution was assessed. Another method to determine the loss of radioactivity to solution was to count aliquots of the digestive fluids in a high purity germanium detector, using a library of only radium isotopes and their progeny to locate peaks. The combination of results from mass balance and gamma spectrometry outputs allowed for OSU's researchers to determine the bioaccessibility of each soil's radioactive components. Using the determined bioaccessibility and previous animal models, the determination of bioavailability varied between the samples, from zero to 28% of the total initial radioactivity in the samples. A hot particle estimation of the dose from the non-bioavailable portion of the samples yielded a high dose to a small number of cells. Assuming ingestion of the most radioactive sample, (Sum-03a), the amount of damaged (killed) tissue in each section of the gastrointestinal tract was estimated to be less than 0.0407 cm³. This small volume of tissue is not likely to result in evident damage as the healthy human gastrointestinal tract regenerates all surface cells approximately every six days and most items are resident in the digestive system for less than 48 hours. / Graduation date: 2006

Many radiation detection programs use bio-assays, whole-body counters, or air sampling to estimate internal doses. This study examines the possibility of using a common external thermoluminescent dosimeter (TLD) badge as a device for detecting inhaled radionuclides through radiation those radionuclides emit which escape the body. The three common radionuclides chosen for modeling due to their varying decay modes and use or production in the nuclear industry were Cs-137, U-238, and Sr-90. These three radionuclides were modeled for biological and radiological removal in the dynamic systems modeling program of STELLA II and modeled for TLD dose per organ in the geometry and radiation simulation program of MCNP. The results show that none of the nuclides in the study can be detected at air concentrations below regulatory limits for acute inhalation exposures. To achieve a detectable dose from an 8-hour work exposure, with a 90-day wait until the TLD is read, the airborne concentrations for the inhalation classes that produced the most dose per Bq would be 37.9 kBq/m3, 146 MBq/m3, and 1.67 MBq/m3 for Cs-137, U-238, and Sr-90, respectively.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Environmental Sciences." Includes bibliographical references (p. 117-120).

Thesis--Universiteit van Utrecht. / Bibliography: p. 101-104.

The increased worldwide interest in nuclear power and the politically charged threat of nuclear weapons release has made understanding the components, as well as the waste, of nuclear energy an important area of research. More specifically, the identification and selective extraction of the dioxoactinide cations uranyl (UO₂²⁺) and plutonyl (PuO₂⁺), low valent actinides scuh as Am³⁺ or Cm³⁺ and various anions, such as pertechnetate (TcO₄⁻), is essential in the event of a weapons release or the spill of nuclear waste. It has been previously demonstrated that the expanded porphyrin [24]hexaphyrin(1.0.1.0.0.0), commonly referred to as isoamethyrin, displays a dramatic color change, from golden yellow to red, upon coordination of uranyl, neptunyl and plutonyl cations. Chapter 2 details quantitative investigations of isoamethyrin with the uranyl cation as well as the interactions of isoamethyrin with other, potentially competing, cations. This work was carried out in order to assess the ability of isoamethyrin to serve as a colorimetric sensor for the actinide cations. Chapter 3 describes the synthesis and properties of periphery-modified isoamethyrin analogues. The addition of functional groups to this expanded porphyrin allows for immobilization onto a solid support and may enhance its utility as a sensor. Chapter 4 presents the preliminary investigations into the metalation and anion binding properties of a new series of macrocycles, the cyclo[n]pyrroles. Chapter 5 provides experimental methods and characterization data. / text

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