Reactions of uranium oxides and liquid nitrogen tetroxide /

Work performed at the Argonne National Laboratory.

Reactivity of certain uranium oxides with aluminum : terminal report /

"Contract No. AT-30-1 Gen-366."

The carbothermic reduction of uranium oxide /

Uranium oxide has been reduced by carbon under vacuum at 2250°C, to yield a product consisting of dendritic uranium carbide in a matrix of uranium.

Uranium dioxide fuel materials with improved thermal conductivity /

Work performed at the Sylvania-Corning Nuclear Corporation under contract AT (30-1) GEN-366 with the Division of Reactor Development.

Irradiation testing of UO₂ : a literature search /

Included are 167 references to unclassified reports and scientific journals on irradiation testing of unalloyed UO₂. Irradiation behavior and effects, heat transfer calculations, fission gas release, post-irradiation examination, and irradiation capsule design are the subject areas covered.

Progress relating to civilian applications during ...

"Contract No. W-7405-eng-92."

High conductivity UO₂ : terminal report /

Work performed at the Sylvania-Corning Nuclear Corporation under Contract AT-30-1 Gen 366.

The spatial analysis and speciation of uranium and thorium series radionuclides in the soil of the Cronamuck Valley, County Donegal, Ireland

This thesis details the findings of a study into the spatial distribution and speciation of 238U, 226Ra and 228Ra in the soils of the Cronamuck valley, County Donegal . The region lies on the north-eastern edge of the Barnesmore granite and has been the subject of uranium prospecting efforts in the past. The results of the project provide information on the practicability of geostatistical techniques as a means of estimating the spatial distribution of natural radionuclides and provide insight into the behaviour of these nuclides and their modes of occurrence and enrichment in an upland bog environment. The results of the geostatistical survey conducted on the area indicate that the primary control over the levels of the studied nuclides in the soil of the valley is the underlying geology. Isopleth maps of nuclide levels in the valley indicate a predominance of elevated nuclide levels in the samples drawn from the granite region, statistical analysis of the data indicating that levels of the nuclides in samples drawn from the granite are greater than levels drawn from the non-granite region by up to a factor of 4.6 for 238U and 4.9 for 226Ra. Redistribution of the nuclides occurs via drainage systems within the valley, this process being responsible for transport of nuclides away from the granite region resulting in enrichment of nuclides in soils not underlain by the granite. Distribution of the nuclides within the valley is erratic, the effect of drainage f lows on the nuclides resulting in localized enriched areas within the valley. Speciation of the nuclides within one of the enriched areas encountered in the study indicates that enrichment is as a result of saturation of the soil with drainage water containing trace amounts of radionuclides. 238U is primarily held within the labile fractions (exchangeable cat ions + easily oxidisable organics + amorphous iron oxides ) of the soil , 226Ra being associated with the non- labile fractions, most probably the resistant organic material. 228Ra displays a significant occurrence in both the labile and non- labile fractions. The ability of the soil to retain uranium appears to be affected largely by the redox status of the soil, samples drawn from oxidizing environments tending to have little or no uranium in the easily oxidisable and amorphous iron oxide fractions. This loss of uranium from oxidised soil samples is responsible for the elevated 226Ra /238U disequilibrium encountered in the enriched areas of the valley. Analysis of the data indicates that samples displaying elevated 226Ra/238U ratios also exhibit elevated 228Ra/238U ratios indicating a loss of uranium from the samples as opposed to an enrichment of 226Ra.

Major-oxides and trace-elements at DSDP Hole 78-543A

Four chemically distinct basalts were cored in 44 m of basement penetration at Deep Sea Drilling Project Site 543, in Upper Cretaceous crust just seaward of the deformation front of the Barbados Ridge and north of the Tiburon Rise. All four types are moderately fractionated abyssal tholeiites. The four types have different magnetic inclinations, all of reversed polarity, suggesting eruption at different times which recorded secular variation of the earth's magnetic field. Extensive replacement of Plagioclase by K-feldspar has occurred at the top of the basalts, giving analyses with K2O contents up to 5 %. The earliest stages of alteration were dominantly oxidative, resulting in fractures lined with celadonite and dioctahedral smectite, and pervasive replacement of olivine and most intersertal glass with iron hydroxides and green clay minerals. Latef, non-oxidative alteration resulted in formation of olive-green clays and pyrite veins in a portion of the rocks. Basalts affected by this alteration actually lost K2O (to abundances lower than in adjacent fresh basalt glasses), and gained MgO (to abundances higher than in the glasses). Finally, fractures and interpillow voids were lined with calcite, sealing in much fresh glass. Oxygen-isotope measurements on the calcite indicate that this occurred at 12 to 25C. Either altering fluids were warm or the basalts had become buried with a considerable thickness of sediments, such that temperatures increased until a conductive thermal gradient was established, when the veining occurred.

Major element oxides, trace element content and isotopic ratios of dolerites from the Schirmacher Oasis

New results on the petrochemistry and geochemistry of dolerites from the Schirmacher Oasis shed light on the development of the Karoo-Maud plume in Antarctica. The basalts and dolerites are petrologically identical to the rocks of western Dronning Maud Land (DML), which were previously studied and interpreted as a manifestation of the Karoo-Maud plume in Antarctica. The spatial distribution of the dikes suggests eastward spreading of the plume material, up to the Schirmacher Oasis for at least 10 Ma. The geochemical characteristics of magmas from the Schirmacher Oasis reflect the influence of crustal contamination, which accompanied both the ascent and spreading of the plume. The magmas of the initial stage of plume activity (western DML) appeared to be the most contaminated in crustal components. It was found that the geochemical characteristics of Mesozoic magmas from the Schirmacher Oasis are identical to those of enriched tholeiites from the Afanasy Nikitin Rise and the central Kerguelen Plateau (Hole 749), which indicates that their enrichment was related to the ancient material of the Gondwana continent. This was caused by the opening of the Indian Ocean under the influence of the Karoo-Maud plume. This process was peculiar in that it occurred in the presence of nonspreading blocks of varying thickness, for instance, Elan Bank in the central Kerguelen Plateau, and was accompanied by the formation of intraplate volcanic rises, which are documented in the seafloor relief of basins around Antarctica. The geochemical characteristics of igneous rocks from the resulting rises (Afanasy Nikitin, Kerguelen, Naturaliste, and Ninetyeast Ridge) indicate the influence of processes related to crustal assimilation. The magmatism that occurred 40 Ma after the main phase of the Karoo-Maud volcanism at the margins of the adjacent continents of Australia (Bunbury basalts) and India (Rajmahal trapps) could be generated by the Karoo-Maud plume flowing along the developing spreading zone. The plume moved subsequently and was localized at the Kerguelen Plateau, where it occurs at present as an active hotspot.

Concentrations of major-element oxides and minor and trace elements at DSDP Legs 87, 57, 56 and 31

Sediments from Sites 582 (11 samples), 583 (19 samples), 584 (31 samples), 294 (1 sample), 296 (9 samples), 297 (3 samples), 436 (11 samples), and 439 (3 samples) were analyzed by X-ray fluorescence and/or instrumental neutron activation analysis. Ten major elements and 24 minor and trace elements (including 7 rare earth elements) were determined with these methods. Geochemistry varies systematically with both the site location and sediment age. Such variations are explained in terms of changes in sedimentation processes caused by plate motion and changes in ocean currents.

Mineral content, major oxides and trace elements concentrations in clay from different IODP Holes of 331-C0013, 331-C0017, East China sea shelf and different Taiwan rivers

The Okinawa Trough (OT) in the East Asian continental margin is characterized by thick terrigenous sediment and ubiquitous volcanic-hydrothermal activities. In this study, the clays collected during IODP Expedition 331 to the middle OT (Iheya North Knoll) were analyzed for mineralogical and geochemical compositions. By comparing with the clays from the East China Sea shelf and surrounding rivers, we examine different clay origins. The hydrothermal field in the mid-OT is dominated by Mg-rich chlorite, while the recharge zone has clay mineral assemblages similar to the shelf and rivers, showing high content of illite, subordinate chlorite and kaolinite and scarce smectite. Compared to the terrigenous clays, the hydrothermal clays in the OT have high concentrations of Mg, Mn and Zr but low Fe, Na, K, Ca, Ba, Sr, P, Sc and Ti, while the hydrothermal clays in the mid-ocean ridge are relatively enriched in Fe and V and depleted in Al, Mg, Zr, Sc and Ti. Different fractionation patterns of rare earth elements also register in the terrigenous and hydrothermal clays, diagnostic of variable clay origins. We infer that the OT hydrothermal clay was primarily formed by the chemical alteration of detrital sediments subject to the hydrothermal fluids. The remarkably different compositions of hydrothermal clays between the sediment-rich back arc basin like OT and the sediment-starved ocean ridge suggest different physical and chemical processes of hydrothermal fluids and fluid-rock/sediment reactions under various geologic settings.