Pour enrichir les connaissances scientifiques sur les effets biologiques des radionucléides et risques des contaminations chroniques sur la descendance, une étude multigénérationnelle in vivo d’exposition a été réalisée à doses non toxiques d'uranium. Ce modèle, a permis de suivre les effets biologiques de l’uranium sur trois générations de rats (F0, F1 et F2) par des analyses cliniques et le suivi de marqueurs biologiques. Dans cette étude, des analyses métabolomiques, transcriptomiques et épigénomiques ont été réalisées à partir d’échantillons de sang, d’urine et de rein.Pour la première génération des rats contaminés (F0), des différences dépendant du sexe des animaux sont observables par l’analyse des niveaux d’expression géniques (ARNm et micro-ARN) dans les reins, des profils métabolomiques et biochimiques dans les reins, l’urine et le sang. Aucune modification épigénétique des profils de méthylation de l’ADN rénal n’est à noter. Pour les deux générations suivantes (F1 et F2), un effet multigénérationnel dépendant aussi du sexe des rats est observable au niveau des profils métabolomiques urinaires et rénaux ainsi qu’au niveau des profils épigénétiques de méthylation de l'ADN des reins. Une baisse de poids corporel et des reins a aussi été observée pour la troisième génération de rats chez les mâles (F2).En conclusion, les travaux de cette thèse montrent qu’une contamination chronique à faible dose d'uranium entraine des effets biologiques sur plusieurs générations de rats. Ils sont observables à différents niveaux moléculaires des systèmes de régulation cellulaires et dépendent du sexe des rats. Ces effets, étroitement liés à des systèmes biologiques intégrés, sont utiles à la compréhension des mécanismes biologiques des expositions à l'uranium et à l’évaluation des risques de nocivités à long termes. Dans le domaine de la radioprotection, ces résultats justifient la nécessité de considérer les dimorphismes sexuels des individus et les conséquences des expositions sur les générations à venir. / In order to deepen scientific knowledge regarding biological effects of radionuclides and associated risk to offspring, an in vivo multigenerational study of chronic exposure to a non-toxic dose of uranium was performed by monitoring three generation of rats (F0, F1 and F2). Clinical parameters and biological markers, including metabolomics, transcriptomics and epigenomics high throughput analysis were conducted in blood, urine and kidney samples.For the first generation of contaminated rats (F0) sex-differences to uranium effects were observed in kidney for gene expression (mRNA, miRNA) and in kidney, urine and blood for biochemical parameters and metabolomics profiles. No epigenetic modification of DNA methylation profiles was shown in kidney. For the next two generations (F1, F2), a multigenerational sex-specific effect is observed for both metabolomics and renal DNA methylation profiles of contaminated rats. Moreover, for the last generation of male rats (F2), a decrease of both total body and kidney weight was shown.In conclusion, low-dose chronic contamination of rats to uranium leads to multigenerational effects. Including sex-differences, they can be shown at different molecular levels of the cellular system. Depending of integrated system biology, data of this thesis are useful in the understanding of biological mechanisms of uranium effect and risk of delayed harmful effect. In the field of radiation protection, these results prove the requirement of considering sexual dimorphisms and consequences of such exposures to offspring.

Uranium mill tailings from the Ranger mine, located in the Alligator Rivers Region of the Northern Territory, Australia, were examined to assess the effects of weathering and diagenesis on their long-term geochemical stability. Run of mill uranium tailings are a complex heterogeneous mixture of lithogenic ( primary gangue minerals and weathering products ) and secondary ( components that form during milling ) minerals, residual process chemicals and biogenic ( products of biological activity ) phases. Following transfer to the tailings storage facility, post depositional reactions alter the mineralogical and hydrochemical characteristics of the tailings solids and pore waters in accordance with weathering and diagenetic processes. In this thesis, a detailed examination of tailings cores and pore waters, kinetic column test work and geochemical modelling was combined with results from earlier studies to examine the key processes governing the geochemical stability of the Ranger tailings. Conclusions drawn from the work clearly demonstrates that the solid state speciation and mobility of metals and radionuclides in the tailings pile are governed by the processes of oxidative dissolution of sulfide minerals, weathering of phyllosilicates and organic matter diagenesis. The processes are spatially dependent, evolve over time and are influenced by the following key factors : 1. Tailings water content or degree of saturation ; 2. The nature and content of organic matter in the tailings ; 3. Redox potential of the tailings solid - pore water interface ; and 4. The specific reactivity of precursor minerals ( primary / secondary ) from the milling process and pore water solutes. Combined, these processes lead to the formation of authigenic minerals, which control the solubility of pore water constituents. These mechanisms will also have a profound impact on the long-term geochemical stability of the tailings pile and, as such, will need to be taken into account in the design, management and closure of the final tailings repositories at the Ranger site. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2004.

Past monitoring has noted benthic macroinvertebrate community impairment downstream of both the Key Lake and Rabbit Lake uranium operations in northern Saskatchewan, Canada. The objective of this research was to try to identify the cause(s) of these impacts using a weight-of-evidence approach. Given that sediments generally accumulate contaminants that are related to metal mining activities (such as metals and radionuclides), the initial hypothesis for this research was that contaminated sediments were the primary cause of benthic community impairment at both operations.<p>In 2003 and 2004 a Sediment Quality Triad (SQT) approach confirmed the presence of an effect on benthic community structure, in addition to significant differences in surface-water, pore-water and whole-sediment chemistry at the immediate down-stream exposure sites at both uranium operations. However, no significant adverse effects were noted in 10-d whole-sediment bioassays with <i>Hyalella azteca</i>, although this lack of response could be partially due to sediment pore-water dilution resulting from the automated clean overlying water renewal process employed. Potential causes of benthic community impairment identified through the 2003 and 2004 SQTs for Key Lake include physical sediment composition, surface water pH and total ammonia, in addition to pore-water total ammonia and arsenic. Potential stressors identified at Rabbit Lake included high surface water manganese and uranium concentrations, and increases in pore-water total ammonia, manganese, iron, arsenic, and uranium levels.<p>In the summer of 2004, 4-d in-situ bioassays using <i>H. azteca</i> were conducted along with the SQTs to investigate the role both contaminated surface water and sediment played in benthic community impairment in-situ. Results from the Key Lake in-situ bioassay demonstrated that surface-water was the primary cause of acute toxicity to <i>H. azteca</i>. Results from the Rabbit Lake in-situ study also demonstrated that surface water as the primary cause of acute toxicity to <i>H. azteca</i>, although the relationship was not as strong. The cause of in-situ toxicity at Key Lake could not be correlated with any of the variables measured within the in-situ study, including trace metals, total ammonia, and pH. Of the measured constituents at Rabbit Lake, only concentrations of uranium in both surface water and pore-water were suspected of causing the observed in-situ mortality. Two data sets from two methods of surface water and pore-water collection supported these conclusions.<p>Due to time constraints and stronger cause-effect relationships, efforts were focused on the in-situ toxicity observed at Key Lake. Surface water collected in 2004 at the time of the related in-situ study was also found to be acutely toxic to <i>H. azteca</i> in separate laboratory surface water bioassays, thus verifying that contaminated surface water, not sediment, was the primary cause of the observed in-situ <i>H. azteca</i> mortality. Further information revealed that organic mill-process chemicals, which have been previously linked with sporadic effluent toxicity, were released at the Key Lake operation during the time of the in-situ experiment and associated surface water collection. Additional surface water samples collected in June and August, 2005, were not acutely toxic to <i>H. azteca</i>. Furthermore, a second bioassay with archived surface waters from the initial 2004 collection demonstrated that the water was no longer acutely toxic (i.e., acute toxicity disappeared after one-year storage). Chemistry comparisons of the toxic and non-toxic surface water samples, verified that trace metals, ammonia, pH, and major ions, including sulphate, were not the cause of toxicity, leaving only organic mill-process chemicals as a possible cause. Subsequent 4-d laboratory toxicity tests demonstrated that these process chemicals (kerosene, amine, and isodecanol) are toxic to H. azteca at the levels released in 2004, and are therefore believed to be the cause of the <i>H. azteca</i> mortality seen in the earlier in-situ experiment.<p>In short, this weight-of-evidence research provided new information on the possible causes of benthic macroinvertebrate community impairment downstream of both the Key Lake and Rabbit Lake uranium operations.

Past monitoring has noted benthic macroinvertebrate community impairment downstream of both the Key Lake and Rabbit Lake uranium operations in northern Saskatchewan, Canada. The objective of this research was to try to identify the cause(s) of these impacts using a weight-of-evidence approach. Given that sediments generally accumulate contaminants that are related to metal mining activities (such as metals and radionuclides), the initial hypothesis for this research was that contaminated sediments were the primary cause of benthic community impairment at both operations.<p>In 2003 and 2004 a Sediment Quality Triad (SQT) approach confirmed the presence of an effect on benthic community structure, in addition to significant differences in surface-water, pore-water and whole-sediment chemistry at the immediate down-stream exposure sites at both uranium operations. However, no significant adverse effects were noted in 10-d whole-sediment bioassays with <i>Hyalella azteca</i>, although this lack of response could be partially due to sediment pore-water dilution resulting from the automated clean overlying water renewal process employed. Potential causes of benthic community impairment identified through the 2003 and 2004 SQTs for Key Lake include physical sediment composition, surface water pH and total ammonia, in addition to pore-water total ammonia and arsenic. Potential stressors identified at Rabbit Lake included high surface water manganese and uranium concentrations, and increases in pore-water total ammonia, manganese, iron, arsenic, and uranium levels.<p>In the summer of 2004, 4-d in-situ bioassays using <i>H. azteca</i> were conducted along with the SQTs to investigate the role both contaminated surface water and sediment played in benthic community impairment in-situ. Results from the Key Lake in-situ bioassay demonstrated that surface-water was the primary cause of acute toxicity to <i>H. azteca</i>. Results from the Rabbit Lake in-situ study also demonstrated that surface water as the primary cause of acute toxicity to <i>H. azteca</i>, although the relationship was not as strong. The cause of in-situ toxicity at Key Lake could not be correlated with any of the variables measured within the in-situ study, including trace metals, total ammonia, and pH. Of the measured constituents at Rabbit Lake, only concentrations of uranium in both surface water and pore-water were suspected of causing the observed in-situ mortality. Two data sets from two methods of surface water and pore-water collection supported these conclusions.<p>Due to time constraints and stronger cause-effect relationships, efforts were focused on the in-situ toxicity observed at Key Lake. Surface water collected in 2004 at the time of the related in-situ study was also found to be acutely toxic to <i>H. azteca</i> in separate laboratory surface water bioassays, thus verifying that contaminated surface water, not sediment, was the primary cause of the observed in-situ <i>H. azteca</i> mortality. Further information revealed that organic mill-process chemicals, which have been previously linked with sporadic effluent toxicity, were released at the Key Lake operation during the time of the in-situ experiment and associated surface water collection. Additional surface water samples collected in June and August, 2005, were not acutely toxic to <i>H. azteca</i>. Furthermore, a second bioassay with archived surface waters from the initial 2004 collection demonstrated that the water was no longer acutely toxic (i.e., acute toxicity disappeared after one-year storage). Chemistry comparisons of the toxic and non-toxic surface water samples, verified that trace metals, ammonia, pH, and major ions, including sulphate, were not the cause of toxicity, leaving only organic mill-process chemicals as a possible cause. Subsequent 4-d laboratory toxicity tests demonstrated that these process chemicals (kerosene, amine, and isodecanol) are toxic to H. azteca at the levels released in 2004, and are therefore believed to be the cause of the <i>H. azteca</i> mortality seen in the earlier in-situ experiment.<p>In short, this weight-of-evidence research provided new information on the possible causes of benthic macroinvertebrate community impairment downstream of both the Key Lake and Rabbit Lake uranium operations.

A [U-232]UBe13 neutron source was designed and modeled and the fluence and flux distributions were calculated. The [U-232]U decay chain emits six high energy alpha particles in quick succession and is ideal for use in a beryllium (a,n) neutron source. [U-232]U is an undesirable byproduct in the production of [U-233]U in the thorium fuel cycle; its concentrations can vary from 5-3000 ppm in bred [U-233]U. A 1.1018-cm diameter by 1.1018-cm tall cylinder of [U-233]UBe13 with 300ppm U-232 at 0.74 GBq (20 mCi) was modeled and found to have a peak yield of 3.5*105 n/s after 10.17 years. At this peak yield, the [U-232]UBe13 source has better neutron production efficiency per initial alpha emission activity than other beryllide neutron sources.

The following is a thesis presented on the history, subsurface characterization and settlement analysis of the Conquista Tailings Impoundment located in Karnes City, TX. This research draws information from readily available sources at TCEQ in Austin, Texas. Documents included in this report date back to the mid-1980s and can be as recent as 2011. This thesis will focus on the eastern section of the Conquista Tailings Impoundment and will primarily observe and predict the settlement experienced in this portion of the site. The site has been analyzed using one-dimensional consolidation analysis, based on three (3) loading factors, and has been modeled using finite element analysis aided by the software PLAXIS. The research has justified the magnitude of settlement that has occurred in the area of concern and has provided just reasoning for the events. Further investigations into the subsurface conditions in the eastern portion of the Conquista Tailings Impoundment will be needed to confirm and refine the analysis presented. / text

Natürliche Biofilme von zwei urankontaminierten Standorten, dem ehemaligen Uranbergwerk in Königstein (Sachsen) und dem Gebiet der ehemaligen Aufstandsfläche der Gessenhalde (Thüringen), wurden in dieser Arbeit näher untersucht. An beiden Standorten konnte in den Minenwässern die hochmobile, gelöste Uranspezies Uranylsulfat (UO2SO4) als dominierend nachgewiesen werden. Aufgrund der Instabilität vieler kommerzieller Fluoreszenzfarbstoffe bei niedrigen pH-Werten war eine gezielte Anfärbung der Mikroorganismen in den sauren Biofilmen nicht möglich, ohne den pH-Wert der Biofilmproben anzuheben, was die Probenchemie maßgeblich verändert. In Kooperation mit der Firma DYOMICS (Jena, Deutschland) wurden neue, kommerziell nicht erhältliche, säurestabile Farbstoffe erstmals hinsichtlich ihrer Eignung zur Anfärbung von Mikroorganismen in sauren Biofilmen ohne Veränderung des pH-Wertes sowie der sonstigen Probenchemie getestet. Die neuen Farbstoffe DY-601XL, V07-04118, V07-04146 und DY-613 zeigten eine Eignung für solche Färbungen, da sie eine intensive Anfärbung der Mikroorganismen bei niedrigen pH-Werten unter pH 3 – 4 herbeiführen und außerhalb des Emissionsbereiches von Uran fluoreszieren. In dieser Arbeit wurde die Fähigkeit von Euglena Mutabilis-Zellen zur Bioakkumulation des Urans im pH-Wertbereich 3 – 6 in den Hintergrundmedien Natriumperchlorat (9 g/l) oder Natriumsulfat (3,48 g/l) an lebenden Zellen untersucht. Unabhängig vom Medium konnte bei sauren pH-Werten um pH 3 – 4 über 90 % des vorgelegten Urans aus den Probelösungen abgetrennt werden. Die Speziation des an den Euglena-Zellen akkumulierten Urans, wurde mittels laserinduzierter Fluoreszenzspektroskopie (LIFS) untersucht. Es zeigte sich, dass unabhängig vom Hintergrundmedium, Lebenszustand und pH-Wert eine vergleichbare neue Uranspezies an den Zellen gebildet wird. Durch den Vergleich der Daten aus den LIFS-Messungen mit Referenzwerten, konnte die gebildete Uranspezies auf eine Anbindung durch (organo)phosphatische und/oder carboxylische funktionelle Gruppen eingegrenzt werden. Mit Hilfe der zeitaufgelösten FT-IR-Spektroskopie konnte die carboxylische Anbindung des Urans an toten Zellen nachgewiesen werden. Ein Ausschluss der (organo)phosphatischen Komplexierung konnte jedoch mit dieser Methode nicht geführt werden. Untersuchungen zur Lokalisation des Urans an bzw. in den Zellen, mittels der gekoppelten CLSM/LIFS-Technik zeigten erstmals ein Indiz für die intrazelluläre Akkumulation von Uran in den lebenden Zellen. Ergänzende TEM/EDX-Messungen bestätigten die intrazelluläre Aufnahme und belegen eine Akkumulation in runden bis ovalen Zellorganellen, bei denen es sich vermutlich um Vakuolen oder Vakuolen-ähnliche Vesikel handelt. An den toten Zellen konnte mit diesen Methoden kein Uran detektiert werden. Dies lässt auf eine passive, homogen verteilte Biosorption des Urans an die verfügbaren Bindungsplätze an der Zelloberfläche der toten Biomasse schließen.

Oregon State University is home to a TRIGA® Mark II reactor. In October of 2008, the reactor began operating on low enriched uranium fuel. A model of the facility exists in MCNP, a Monte Carlo code that can be used for criticality calculations. Until now, a bias in the calculation of the neutron multiplication factor has been carried forward from outdated core models. This work involves updating various aspects of the model, including the geometry of the facility as well as materials and their properties, in order to arrive at a more accurate representation of the facility as it is today. The individual effect that each change has on the results of MCNP calculations of the core is documented. Following the updates to the model, the model can emulate records that describe the startup of the reactor in October of 2008. The results of these calculations can be compared to actual data in order to establish a foundation for benchmarking the model and characterizing the reactor core. The deviation between calculated and expected results can be used to determine a single reactivity bias in the model. The bias determined as a result of this work can be applied to future calculations using the model developed as a part of this work. / Graduation date: 2013

Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

Thesis (M.Eng.) - Carleton University, 2001. / Includes bibliographical references (p. 156-158). Also available in electronic format on the Internet.