Browsing by Subject "Uranium"
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Item A calorimetric study of the 8-quinolinol chelates of thorium (IV) and uranium (VI)(Texas Tech University, 1957-08) Van Tassel, James HenryNot availableItem A study of the solvated chelates of scandium, thorium, and uranium with 8-quinolinol and 2-methyl-8-quinolinol(Texas Tech University, 1959-08) Van Tassel, James HenryNot availableItem Advances in gamma-ray spectroscopy : compton suppression and gamma-gamma coincidence(2011-05) Horne, Steven Michael; Landsberger, Sheldon; Biegalski, StevenThis project aims to improve research in gamma-ray spectroscopy by using advanced detector systems. These systems are designed to reduce interference inherent in gamma-ray spectroscopy by rejecting Compton scattering events from high-energy gamma-rays, as well as look at cascading decays of gamma-rays through gamma-gamma coincidence counting. By combining these methods, one is able to lower detection limits for many elements than would otherwise be possible. This work also takes advantage of neutron activation analysis, which allows stable elements to be analyzed by activating them with neutrons, causing them to become unstable and decay with radioactive signatures. By analyzing these signatures, one is able to detect trace levels of elements with relatively small samples sizes (< 1g) and in a nondestructive manner.Item Characterization of Alpha-Phase Sintering of Uranium and Uranium-Zirconium Alloys for Advanced Nuclear Fuel Applications(2012-02-14) Helmreich, GrantThe sintering behavior of uranium and uranium-zirconium alloys in the alpha phase were characterized in this research. Metal uranium powder was produced from pieces of depleted uranium metal acquired from the Y-12 plant via hydriding/dehydriding process. The size distribution and morphology of the uranium powder produced by this method were determined by digital optical microscopy. Once the characteristics of the source uranium powder were known, uranium and uranium-zirconium pellets were pressed using a dual-action punch and die. The majority of these pellets were sintered isothermally, first in the alpha phase near 650?C, then in the gamma phase near 800?C. In addition, a few pellets were sintered using more exotic temperature profiles. Pellet shrinkage was continuously measured in situ during sintering. The isothermal shrinkage rates and sintering temperatures for each pellet were fit to a simple model for the initial phase of sintering of spherical powders. The material specific constants required by this model, including the activation energy of the process, were determined for both uranium and uranium-zirconium. Following sintering, pellets were sectioned, mounted, and polished for imaging by electron microscopy. Based on these results, the porosity and microstructure of the sintered pellets were analyzed. The porosity of the uranium-zirconium pellets was consistently lower than that of the pure uranium pellets. In addition, some formation of an alloyed phase of uranium and zirconium was observed. The research presented within this thesis is a continuation of a previous project; however, this research has produced many new results not previously seen. In addition, a number of issues left unresolved by the previous project have been addressed and solved. Most notably, the low original output of the hydride/dehydride powder production system has been increased by an order of magnitude, the actual characteristics of the powder have been measured and determined, shrinkage data was successfully converted into a sintering model, an alloyed phase of uranium and zirconium was produced, and pellet cracking due to delamination has been eliminated.Item Comprehensive Investigation of the Uranium-Zirconium Alloy System: Thermophysical Properties, Phase Characterization and Ion Implantation Effects(2013-07-31) Ahn, SangjoonUranium-zirconium (U-Zr) alloys comprise a class of metallic nuclear fuel that is regularly considered for application in fast nuclear energy systems. The U-10wt%Zr alloy has been demonstrated to very high burnup without cladding breach in the Experimental Breeder Reactor-II (EBR-II). This was accomplished by successfully accommodating gaseous fission products with low smear density fuel and an enlarged cladding plenum. Fission gas swelling behavior of the fuel has been experimentally revealed to be significantly affected by the temperature gradient within a fuel pin and the multiple phase morphologies that exist across the fuel pin. However, the phase effects on swelling behavior have not been yet fully accounted for in existing fuel performance models which tend to assume the fuel exists as a homogeneous single phase medium across the entire fuel pin. Phase effects on gas bubble nucleation and growth in the alloy were investigated using transmission electron microscopy (TEM). To achieve this end, a comprehensive examination of the alloy system was carried out. This included the fabrication of uranium alloys containing 0.1, 2, 5, 10, 20, 30, 40, and 50 wt% zirconium by melt-casting. These alloys were characterized using electron probe micro-analysis (EPMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Once the alloys were satisfactorily characterized, selected U-Zr alloys were irradiated with 140 keV He^(+) ions at fluences ranging from 1 ? 10^(14) to 5 ? 10^(16) ions/cm^(2). Metallographic and micro-chemical analysis of the alloys indicated that annealing at 600 ?C equilibrates the alloys within 168 h to have stable ?-U and ?-UZr_(2) phase morphologies. This was in contrast to some reported data that showed kinetically sluggish ?-UZr_(2) phase formation. Phase transformation temperatures and enthalpies were measured using DSC-TGA for each of the alloys. Measured temperatures from different time annealed alloys have shown consistent matches with most of the features in the current U-Zr phase diagram which further augmented the EPMA observed microstructural equilibrium. Nevertheless, quantitative transformation enthalpy analysis also suggests potential errors in the existing U-Zr binary phase diagram. More specifically, the (?-U, ?2) phase region does not appear to be present in Zr-rich (> 15 wt%) U-Zr alloys and so further investigation may be required. To prepare TEM specimens, characterized U-Zr alloys were mechanically thinned to a thickness of ~150 ?m, and then electropolished using a 5% perchloric acid/95% methanol electrolyte. Uranium-rich phase was preferentially thinned in two phase alloys, giving saw-tooth shaped perforated boundaries; the alloy images were very clear and alloy characterization was accomplished. During in-situ heating U-10Zr and U-20Zr alloys up to 810 ?C, selected area diffraction (SAD) patterns were observed as the structure evolved up to ~690 ?C and the expected ?-U ? ?-U phase transformation at 662 ?C was never observed. For the temperature range of the (?-U, ?2) phase region, phase transformation driven diffusion was observed as uranium moved into Zr-rich phase matrix in U-20Zr alloy; this was noted as nonuniform bridging of adjacent phase lamellae in the alloy. From the irradiation tests, nano-scale voids were discovered to be evenly distributed over several micrometers in U-40Zr alloys. For the alloys irradiated at the fluences of 1 ? 10^(16) and 5 ? 10^(16) ions/cm^(2), estimated void densities were proportional to the irradiation doses, (250 ? 40) and (1460 ? 30) /?m^(2), while void sizes were fairly constant, (6.0 ? 1.5) and (5.2 ? 1.2) nm, respectively. Measured data could be foundational inputs to the further development of a semi-empirical metal fuel performance model.Item A cost estimate for uranium recovery from seawater using a chitin nanomat adsorbent(2014-05) Lindner, Harry Dreyfus; Schneider, Erich A.Even at 3.3 ppb, seawater contains a uranium supply large enough to power the world’s nuclear fleet for 13,000 years. This large supply has prompted interest in technologies for recovering uranium from seawater. Since the 1960’s, economic models of such technologies have failed to produce an economically competitive strategy when compared to conventional uranium recovery from terrestrial mining. Thus, uranium from seawater is researched as a potential price ceiling because of the large supply but high recovery cost. Such an upper bound is still valuable research because it allows for more certainty in uranium prices for planning, research, development and deployment of nuclear power systems. This thesis explores past cost estimates for uranium recovery from seawater and adds a new cost estimate to the pool of literature. The past estimates showed a development from systems that actively moved seawater to systems that allowed adsorbent to sit passively in seawater. The adsorbent material changed from hydrous titanium oxide to the higher-capacity amidoxime ligand. Capacity was the strongest driver of cost. Early models with the amidoxime ligand used an acrylic substrate or backbone. This substrate was later replaced by polyethylene because of its increased durability and lower cost. However, each of those materials could contribute to the problem of plastics in the ocean. The new technology assessed for cost in this paper attempts to address the plastics concern by replacing the plastic with a high molecular weight chitin nanomat as the substrate for the amidoxime ligand. The cost assessment showed the technology is presently cost prohibitive largely due to the adsorption capacity and chitin nanomat production costs. To increase capacity, the grafting efficiency onto the chitin substrate must be improved in order to achieve capacities comparable to those observed for the amidoxime-polyethylene adsorbent. To reduce chitin nanomat production costs, the ionic liquid (IL) consumption must be reduced and the recyclability of IL must be achieved.Item Determination of fission product yields of 235U using gamma ray spectroscopy(2012-12) Lu, Christopher Hing; Biegalski, Steven R.; Landsberger, SheldonIt is important to have a method of experimentally calculating fission product yields. Statistical calculations and simulations produce very large uncertainties. Experimental calculations, depending on the methods used, tend to produce lower uncertainties. This work set up a method to calculate fission product yields using gamma ray spectroscopy. In order to produce a method that was theoretically sound, a simulation was set up using OrigenArp to calculate theoretical concentrations of fission products from the irradiation of natural uranium. From these concentrations, the fission product yields were calculated to verify that they would agree with expected values. Moving forward in the work, the total flux at the point of irradiation, in the pneumatic transfer system, was calculated and determined to be 3.9070E+11 ± 6.9570E+10 n/cm^2/s at 100 kW. Once the flux was calculated, the method for calculating fission product yields was implemented and yields were calculated for 10 fission products. The yields calculated were in very good agreement (within 10.04%) with expected values taken from the ENDF-349 library. This method has strong potential in nuclear forensics as it can provide a means for developing a library of experimentally-determined fission product yields, as well as rapid post-nuclear detonation analysis.Item Evaluation of settlements at the Conquista Tailings impoundment(2012-12) Sheridan, Todd Michael; Zornberg, Jorge G.; Gilbert, Robert B. (Robert Bruce), 1965-; Liljestrand, HowardThe 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.Item Hot Extrusion of Alpha Phase Uranium-Zirconium Alloys for TRU Burning Fast Reactors(2012-02-14) Hausaman, Jeffrey StephenThe development of fast reactor systems capable of burning recycled transuranic (TRU) isotopes has been underway for decades at various levels of activity. These systems could significantly alleviate nuclear waste storage liabilities by consuming the long-lived isotopes of plutonium (Pu), neptunium (Np), americium (Am), and curium (Cm). The fabrication of metal fuel alloys by melt casting pins containing the volatile elements Am and Np has been a major challenge due to their low vapor pressures; initial trials demonstrated significant losses during the casting process. A low temperature hot extrusion process was explored as a potential method to fabricate uranium-zirconium fuel alloys containing the TRU isotopes. The advantage of extrusion is that metal powders may be mixed and enclosed in process canisters to produce the desired composition and contain volatile components. Uranium powder was produced for the extrusion process by utilizing a hydride-dehydride process that was developed in conjunction with uranium alloy sintering studies. The extrusions occurred at 600 degrees C and utilized a hydraulic press capable of 450,000 N (50 tons) of force. Magnesium (Mg) metal was used as a surrogate metal for Pu and Am because of its low melting point (648 degrees C) and relatively high vapor pressure (0.2 atm at 725 degrees C). Samples containing U, Zr, and Mg powder were prepared in an inert atmosphere glovebox using copper canisters and extruded at 600 degrees C. The successful products of the extrusion method were characterized using thermal analysis with a differential scanning calorimeter as well as image and x-ray analysis utilizing an electron microprobe. The analysis showed that upon fabrication the matrix of the extruded metal alloy is completely heterogeneous with no mixing of the metal particle constituents. Further heat treating upon this alloy allows these different materials to interdiffuse and form mixed uraniumz-irconium phases with varying types of microstructures. Image and x-ray analysis showed that the magnesium surrogate present in a sample was retained with little evidence of losses due to vaporization.Item Isotope Ratio Triangulation: A Method for Determining Uranium Isotope Ratios and Application to the Search for Uranium Isotope Anomalies in the Mineral Titanite(2014-11-10) Hill, Joseph RogerThe U-Pb dating methods used in many geochronology laboratories take advantage of a mixed 235U-233U spike for precise uranium isotopic measurements and current data reduction algorithms assume a uniform 238U/235U value of 137.88. Recent re-evaluation of the isotope ratio of ?natural? uranium value used in geochronology has called into question both this value and its constancy in U-bearing minerals, most notably titanite, formed in high-temperature magmatic and metamorphic settings. A 233U-236U spike may be used for direct determination of the uranium isotopic composition, but this spike is not widely used and in some labs where it is, the 238U/235U ratio is not independently measured. Isotope Ratio Triangulation (IRT) is a new and effective method for determining 238U/235U values analyzed with the more common 235U-233U uranium spike. This method leverages the effect of mass-spectrometer-induced isotopic fractionation in three measured ratios to determine 238U/235U values. Graphically, this is represented by three intersecting lines for fractionation factors calculated at varying 238U/235U ratios, hence the term ?triangulation?. The IRT method is here applied to 43 aliquots of 23 titanite samples from a wide range of geologic settings, ages and locations. Of these, five aliquots yielded anomalously high 238U/235U ratios. Three were likely to be entirely uranium blank. Two other samples yielded anomalously high 238U/235U values. Both were roughly 2.5 Ga and coincide with the Archean to early Proterozoic oxidation of the world?s oceans termed the ?Great Oxidation Event?. Low temperature redox reactions have been shown to have a similar depletion effect. These results demonstrate the accuracy of this new method, which can be used to efficiently scan large volumes of existing geochronologic data in search of anomalous U isotope ratios. In addition, results indicate that laboratory blank in the TAMU radiogenic isotope laboratory is not of ?natural? composition. Finally, these results are more consistent with a ?natural? uranium composition of 238U/235U = 137.88 than the recently suggested value of 137.818.Item Measuring the radioactivity of ²³⁵U, ²³⁸U, ²³²Th, and ⁴⁰K in geological matrices using instrumental neutron activation analysis(2012-05) Dolloff, Jason Michel; Landsberger, Sheldon; Biegalski, StevenThe radioactivity contributions of several daughter products of the 235,238 U and 232Th isotope decay chains within geological matrices can be assumed to be in equilibrium due to their age if they have remained undisturbed for an extended period of time. Similarly, one can assume that the isotopic mass proportions are equal to natural isotopic abundance. Current methods used to ascertain activity in these decay chains involve alpha particle spectrometry or ICP-MS, both of which can be laborious and time consuming. In this research, thermal and epithermal neutron activation analysis of small samples of various geological materials is used in order to ascertain activities. Through the use of NAA, cumbersome sample preparation and the need for large sample size and extended counting time are obviated. In addition to the decay chains of uranium and thorium, 40K, another large contributor to naturally occurring radioactivity, is determined using epithermal neutron activation analysis to determine total potassium content, and then calculating its isotopic contribution based on its natural isotopic abundance.Item Modeling energy consumption in the mining and milling of uranium(2010-12) Tavrides, Emily Loree; Schneider, Erich A.; Biegalski, SteveA family of top-down statistical models describing energy consumption in the mining, milling, and refining of uranium are formulated. The purpose of the models is to estimate the energy-to-grade dependence for uranium extraction, while defining a minimum grade that can be feasibly mined and produced. The results serve as a basis for understanding the factors governing energy consumption in the production of U3O8. The models are applied to a considerably larger data set of operating mines than in any previous effort. In addition, the validity of the modeling approach is established by modeling energy for two other commodities, gold and copper, thereby showing it can be applied to other metals. Statistical measures of explanatory power show that the models the energy-to-grade relationship is well-described for both uranium and gold. For copper, there was insufficient data over a broad range of ore grades to obtain a model that passed statistical confidence measures. The results show that mining of lower-grade deposits of uranium is likely to be less energy-intensive than previous investigators concluded. It is shown that the uncertainty in the results is dominated by the contribution of the grade-independent component of energy consumption.Item Optimization of the passive recovery of uranium from seawater(2015-08) Byers, Margaret Elise; Schneider, Erich A.; landsberger, sheldonThe aim of this thesis is to optimize the design and deployment conditions utilized by a technology for passively collecting uranium from seawater that is currently under development by Oak Ridge and Pacific Northwest National Labs along with University partners. This system involves the production, deployment, and recycle of an amidoxime ligand grafted onto a high density polyethylene based adsorbent. While many adsorbent performance characteristics and cost inputs impact the final uranium production cost, the system and design parameters explored here include: degree of ligand grafting, number of adsorbent uses prior to ultimate disposal, length of immersion in the sea, and ocean temperature. Given the complicated empirically-driven nature of the cost calculation, the cost calculation tool is treated as a black box model, thus the minimization requires a derivative free optimization method. A literature review is conducted to explore applicable algorithms and the Nelder-Mead Simplex Method is ultimately selected. A base case is created using historical values to serve as an initial condition for optimization. From this case, the uranium production cost is minimized, resulting in an 11% decrease. From there, sensitivity cases are considered. An alternative elution process for recovering uranium from the adsorbent is studied. If this innovation can be realized, significant cost savings are shown to be attained if this process fulfills its promise of mitigating adsorbent degradation. Next, the effects of marine bacterial growth on cost are explored. It is determined that optimizing the deployment conditions and improving the uranium binding kinetics can mitigate this increase. Sensitivity analyses are conducted in order to provide insight as to how the optimal deployment conditions are determined. The results presented in this thesis can inform the direction of future research. Furthermore, as the technology continues to evolve, the methodology developed for this optimization will remain relevant and the optimization too can continue to be used to guide design and R&D decisions.Item The osteology of Sarahsaurus aurifontanalis and geochemical observations of the dinosaurs from the type quarry of Sarahsaurus (Kayenta Formation), Coconino County, Arizona(2013-05) Marsh, Adam Douglas; Rowe, Timothy, 1953-Sarahsaurus aurifontanalis is the most recent sauropodomorph dinosaur to be discovered and named from the Early Jurassic of North America. The dinosaur is represented by a mostly complete and articulated holotype specimen that preserves a unique manual phalangeal count of 2-3-4-2-2 and accessory pubic foramen adjacent to the obturator foramen. The holotype of Sarahsaurus comprises a braincase and isolated cranial elements, but the skull previously referred to this taxon, MCZ 8893, can only be provisionally referred to Sarahsaurus until additional crania are found associated with postcranial material. Sarahsaurus comes from the middle third of the Kayenta Formation, which is considered to be Early Jurassic in age despite the absence of a radiometric date from that unit. A new technique used to obtain a U-Pb radiometric date from the type quarry of Sarahsaurus in the Kayenta Formation was influenced by secondary uranium enrichment in the open system of the fossil bone. That suggests that uranium within the Kayenta Formation may be the result of the movement of groundwater during the Laramide orogeny in the Late Cretaceous and Early Eocene, and lends support to the hypothesis that the uplift of the Colorado Plateau began relatively early in Late Cretaceous to the Eocene.Item REE-Be-U-F mineralization of the Round Top laccolith, Sierra Blanca Peaks, Trans-Pecos Texas(2014-05) O'Neill, Laurie Christine; Kyle, J. RichardThe Round Top laccolith is considered to be one of the youngest laccoliths in a series of five known as the Sierra Blanca peaks, located in Hudspeth county, Texas. The laccolith is anomalous within the region in that it is peraluminous and enriched in HREEs, F, and U, and is comprised of intermingled discrete packages of various rhyolite types. The laccolith rhyolite varies in color from gray, purple, red, and tan, which combine locally to form distinct geometric mottled textures. The general composition of the rhyolite is 48-52% potassium feldspar, 28-30% quartz, 8-14% plagioclase feldspar, 4-5% annite biotite, 2-3% magnetite-hematite, 1% zircon, and 1% trace phases. The morphology of the trace phases suggests quenching of a late-stage volatile-rich vapor phase at the time of the laccolith formation. The rhyolite displays a wide array of unique mineralogical characteristics indicative to rapid emplacement and metastable crystallization conditions, including three-part quartz phenocrysts, hourglass sector-zoned potassium feldspars, and late-stage anhedral zircons. Unique accessory and trace phases include cassiterite, cerianite-(Ce), changbaiite, columbite, cryolite, tantalite, thorite, yttrofluorite, yttrocerite, and two unidentified minerals named (W) and (X). Initial alteration of the laccolith by high temperature volatile-rich vapor during the late stages of crystallization caused the partial dissolution of the feldspars and quartz. Subsequent quenching of this high temperature vapor phase produced the abundant interstitial, and pore filling REE-fluorides common to the laccolith. The variation in rhyolite color and the presence of the mottled textures are a direct result of partial oxidation of the laccolith by secondary fluids. The oxidizing fluids migrated within the laccolith along an extensive fracture network, altering the adjacent wallrock by oxidizing magnetite phenocrysts to hematite. The gray, purple, and red rhyolite types reflect an increase in turbidity caused by hematitic inclusions primarily within the pore spaces of the potassium feldspar portions of the groundmass. The tan rhyolite is locally restricted to the base of the laccolith and has been subjected to an intense degree of alteration independent of the other rhyolite types, primarily indicated by the conversion of feldspars to clay. Petrographic, microbeam, and geochemical studies have determined little variation in REE concentration between the three rhyolites of similar alteration intensity, but have indicated a depletion in LREEs within the more altered tan rhyolite. The average REE+Y content for the rhyolites sampled (n=11) ranges between 249 ppm and 518 ppm. The REE+Y concentrations between rhyolite samples of the same type show some variation, possibly indicating a correlation between alteration and REE+Y abundance and/or innate heterogeneity in the vapor phase during the initial laccolith formation. The magma emplaced at Round Top underwent a prolonged evolutionary process of fractionation/differentiation as evident by the unusual mineral assemblage and geochemical enrichment associated with the laccolith (e.g. extremely negative europium anomaly, and the positive La/Yb correlation). Future exploration for Round Top style REE-deposits should center within long-lived, tectonically active and complex regions where laccoliths are likely to exist. Specifically, exploration should focus on identifying the youngest laccolith in a felsic series, as this is the most likely to contain the greatest abundance of incompatible elements within the laccolithic group. The early alteration of feldspars by the high temperature vapor phase was crucial in the development of the REE+Y enrichment at Round Top. The feldspar dissolution provided abundant open pore space that was subsequently filled by the REE-fluorides. Thus, exploration should additionally seek laccoliths that have undergone a similar early alteration process, and expand to potential laccolith groups not yet exposed by erosional processes.Item Safeguards for Uranium Extraction (UREX) +1a Process(2011-08-08) Feener, Jessica S.As nuclear energy grows in the United States and around the world, the expansion of the nuclear fuel cycle is inevitable. All currently deployed commercial reprocessing plants are based on the Plutonium - Uranium Extraction (PUREX) process. However, this process is not implemented in the U.S. for a variety of reasons, one being that it is considered by some as a proliferation risk. The 2001 Nuclear Energy Policy report recommended that the U.S. "develop reprocessing and treatment technologies that are cleaner, more efficient, less waste-intensive, and more proliferation-resistant." The Uranium Extraction (UREX+) reprocessing technique has been developed to reach these goals. However, in order for UREX+ to be considered for commercial implementation, a safeguards approach is needed to show that a commercially sized UREX+ facility can be safeguarded to current international standards. A detailed safeguards approach for a UREX+1a reprocessing facility has been developed. The approach includes the use of nuclear material accountancy (MA), containment and surveillance (C/S) and solution monitoring (SM). Facility information was developed for a hypothesized UREX+1a plant with a throughput of 1000 Metric Tons Heavy Metal (MTHM) per year. Safeguard goals and safeguard measures to be implemented were established. Diversion and acquisition pathways were considered; however, the analysis focuses mainly on diversion paths. The detection systems used in the design have the ability to provide near real-time measurement of special fissionable material in feed, process and product streams. Advanced front-end techniques for the quantification of fissile material in spent nuclear fuel were also considered. The economic and operator costs of these systems were not considered. The analysis shows that the implementation of these techniques result in significant improvements in the ability of the safeguards system to achieve the objective of timely detection of the diversion of a significant quantity of nuclear material from the UREX+1a reprocessing facility and to provide deterrence against such diversion by early detection.Item The simultaneous quantification of fissile U and Pu nuclides using delayed neutron activation analysis(2013-05) Kapsimalis, Roger James, 1985-; Landsberger, SheldonThe ability to quickly and accurately quantify fissile constituents in bulk materials remains essential to many aspects of nuclear forensics and for safeguarding nuclear materials and operations. This often entails the analysis of trace quantities of nuclear debris or effluents, and typically requires bulk sample digestion followed by actinide separation and mass spectrometry. Because destructive methods are time and labor intensive, efforts have been made to develop alternative nondestructive methods for this type of analysis. This work, performed at Oak Ridge National Laboratory at the High Flux Isotope Reactor (HFIR), seeks to utilize delayed neutron activation analysis on samples of interest containing multiple fissile constituents. Based on the variances in the fission product yields of individual fissile nuclides, this work utilizes methods of linear regression to derive a technique that allows for such analysis, forgoing chemical separation and using only a single irradiation and counting step.Item The chemistry of the solvated metal chelates of uranium (VI), thorium (IV), and scandium (III) with 8-quinolinol and substituted 8-quinolinols(Texas Tech University, 1963-05) Horton, Guy RobertNot availableItem Uranium Powder Production Via Hydride Formation and Alpha Phase Sintering of Uranium and Uranium-zirconium Alloys for Advanced Nuclear Fuel Applications(2010-07-14) Garnetti, David J.The research in this thesis covers the design and implementation of a depleted uranium (DU) powder production system and the initial results of a DU-Zr-Mg alloy alpha phase sintering experiment where the Mg is a surrogate for Pu and Am. The powder production system utilized the uranium hydrogen interaction in order to break down larger pieces of uranium into fine powder. After several iterations, a successful reusable system was built. The nominal size of the powder product was on the order of 1 to 3 mm. The resulting uranium powder was pressed into pellets of various compositions (DU, DU-10Zr, DU-Mg, DU-10Zr-Mg) and heated to approximately 650?C, just below the alphabeta phase transition of uranium. The dimensions of the pellets were measured before and after heating and in situ dimension changes were measured using a linear variable differential transducer (LVDT). Post experiment measurement of the pellets proved to be an unreliable indicator of sintering do the cracking of the pellets during cool down. The cracking caused increases in the diameter and height of the samples. The cracks occurred in greater frequency along the edges of the pellets. All of the pellets, except the DU-10Zr-Mg pellet, were slightly conical in shape. This is believed to be an artifact of the powder pressing procedure. A greater density occurs on one end of the pellet during pressing and thus leads to gradient in the sinter rate of the pellet. The LVDT measurements proved to be extremely sensitive to outside vibration, making a subset of the data inappropriate for analysis. The pellets were also analyzed using electron microscopy. All pellets showed signs of sintering and an increase in density. The pellets will the greatest densification and lowest porosity were the DU-Mg and DU-10Zr-Mg. The DU-Mg pellet had a porosity of 14 +or- 2.%. The DU-10Zr-Mg porosity could not be conclusively determined due to lack of clearly visible pores in the image, however there were very few pores indicating a high degree of sintering. In the DU-10Zr-Mg alloy, large grains of DU were surrounded by Zr. This phenomena was not present in the DU-10Zr pellet where the Zr and DU stayed segregated. There was no indication of alloying between the Zr and DU in pellets.