Chemical composition uranium oxide

The chondrite-normalized REE patterns for basement-hosted uranium oxides are similar, except for a small variation of LREE abundances, indicating identical physico-chemical deposition conditions (T, pH, fluid composition) for the Eastern part of the Athabasca Basin basement. The previous REE distinction made between Ingress and Egress deposits (Fayek Kyser 1997) is not confirmed by the present study, because both types have similar REE abundance and fractionations, indicating the similarity of the sources and the processes for both deposit types. Thus, these results suggest... 

The importance of the chemical composition of these inorganic deposits in regard to ion emission has been understood for many years and is illustrated by the work of Studier et al. [6]. A deposit of uranium on a hot filament emitted a variety of ions, depending on the oxidizing and reducing agents added to the material. They presented their data in the following format ... 

Our experiments are carried out in the presence of various types of micro-porous solids. They consist principally of alumina (CA), silica (CS), and activated charcoal (EC). For irradiation purposes with fission fragments, uranium is incorporated as an oxide by impregnation or coprecipitation methods. Microporous solids with variable uranium content are made available in this way with, as supporting phase, alumina (CAU), silica (CSU), and activated charcoal (ECU) 8, 9), respectively. Quite apart from the chemical composition, the knowledge of the physical structure of these solids is particularly important. For this reason a series of systematic measurements have been carried out on these solids of granulometry between 15 and 30 mesh. 

Carbothermic Plasma-Chemical Reduction of Uranium Oxide (U3O8). Analyze the stoichiometry of the carbothermic reduction of U3O8 (7-24). Explain why the ratio of molar fractions of CO2 and CO in products of the process is not fixed. Find out the relation between the molar fractions of CO2 and CO in the products as a function of initial composition of the solid mixture U3O8-C. Explain why the carbothermic reduction process of UO2 (7-23) assumes only CO in products, while that of U3O8 (7-24) expects formation of CO and CO2. 

RU is one of the products of conventional chemical reprocessing of spent uranium oxide fuel. In this context, RU is simply a subset of SEU, acquired on the open market, as is SEU or natural uranium, and its use is not linked to the reprocessing of the spent fuel of the utility acquiring the material. It is considered simply as an alternate source of enrichment (anticipated to be much cheaper) compared with SEU from enriching fresh uranium and can be substituted by SEU of equivalent enrichment. The enrichment level is around 0.9%, with the actual U content and composition depending on the initial enrichment and burnup of the spent fuel from whence it was obtained. In general, reactor physics and fuel performance will be comparable with that for 0.9% SEU. 

Given the variety of important actinide oxidation states, what naturally occurring anion would best effect actinide mineralization The lanthanides, chemically analogous to the trivalent actinides, occur naturally in three commercially important forms monazite and xenotime, which are orthophosphate minerals, and bastnasite, which has the approximate composition LnFCOs. Uranium ores may be divided into... 

Applications of EPMA include elemental analysis of surfaces and of micron-sized features at a surface. The sensitivity of the method is about 0.2 atom%. It provides a rapid, accurate method for compositional analysis of microscopic features. Elemental mapping of the elements present at the surface can also be done, and the composition correlated to topographical maps obtained from an analytical microscopy method, allowing correlation of topographical features of a surface with elemental composition. Like XRF, EPMA is strictly an elemental analysis technique no information on chemical spe-ciation or oxidation state is obtained. AU elements from boron to uranium can be determined. Given that X-rays can escape from depths of 1000 A or so, EPMA has the deepest definition of surface of the techniques discussed in this chapter. In fact, like XRF, it can be considered to be a bulk analysis technique assuming the sample is homogeneous. 

Highlights The characterization of UO2 powders and pellets to examine compliance with specifications involves the use of several physical and analytical test methods. The chemical analyses include determination of the uranium content and isotopic composition, the 0 U ratio, and the measurement of the content of several elemental impurities. Of special importance are elements that may affect the neutron absorption properties of the fuel pellets. Each of these elements is determined and the total neutron absorption of all these impurities is summed up as EEC. Modern nuclear fuel may include burnable neutron poisons that are used to increase the operational lifespan of the fuel. The intentional addition of these poisons, like gadolinia, must be carefully controlled to avoid fluctuations of the neutron density in the reactor. Basically, after dissolution of the nranium oxide samples the analytical methods that... 

Radiation failures are principally caused by uranium and thorium contaminants and secondary cosmic rays. Radiation can cause wearout, aging, embrittlement of materials, or overstress soft errors in such electronic hardware as logic chips. Chemical failures occur in adverse chemical environments that result in corrosion, oxidation, or ionic surface dendritic growth. There may also be interactions between different types of stresses. For example, metal migration maybe accelerated in the presence of chemical contaminants and composition gradients and a thermal load can accelerate the failure mechanism due to a thermal expansion mismatch. 

---