This paper analyzes several prevalent misconceptions about nuclear fuel cycles that breed fissile uranium-233 from thorium. Its main conclusions are: a Uranium-233, despite the gamma radioactivity of associated isotopes, is a rather attractive material for making fission bombs, and is a credible material for subnational as well as national groups to use for this purpose. e "Pure" thorium cycles...

The determination of radium and/or uranium concentrations in natural waters is useful in a wide range of environmental studies. In this work, a low-background liquid scintillation system (Wallac, Quantulus 1220) was used to determine simultaneously 226Ra and uranium (total) activities in natural water samples. Sample preparation involved filtration and 1 : 10 concentration by evaporation. Then,...

Shortly before the Second World War time, Nishina reported on a series of prominent nuclear physical and radiochemical studies in collaboration with Kimura. They artificially produced (231)Th, a member of the natural actinium series of nuclides, by bombarding thorium with fast neutrons. This resulted in the discovery of (237)U, a new isotope of uranium, by bombarding uranium with fast neutrons,...

A natural uranium silicate mineral, cuprosklodowskite, has been analyzed by Resonance Ionization Mass Spectrometry (RIMS) for uranium isotope composition under a variety of experimental conditions. While no significant isobaric interferences are observed in the mass regions of interest, molecular supression is incomplete, and varies with the method of neutral U atom production. Despite low meas...

The fate of uranium in natural systems is of great environmental importance. X-ray absorption near-edge spectroscopy (XANES) revealed that U(VI) was reduced to U(IV) in shallow freshwater sediment at an open pit in an inactive uranium mine. Geochemical characterization of the sediment showed that nitrate, Fe(III), and sulfate had also been reduced in the sediment. Observations of the sediment p...

Biotransformation of various chemical forms of uranium present in wastes, contaminated soils and materials by microorganisms under different process conditions such as aerobic and anaerobic (denitrifying, iron-reducing, fermentative, and sulfate-reducing) conditions will affect the solubility, bioavailability, and mobility of uranium in the natural environment. Fundamental understanding of the ...

A separation methodology to isolate natural uranium from its radioactive daughters: Th, Ra, Bi, Pb, Pa and Po, was developed using an only one anion exchange resin and varying concentrations of HCl solutions. Three types of anion exchange resins were tested and the separation process was followed by gamma and alpha spectrometry. Uranium can be quantitatively isolated from its descendants using ...

Ecological consequences of depleted uranium (DU) released to the environment as a result of military use of DU munitions were appraised by reviewing pertinent literature. Estimates were based upon ecosystem responses to natural uranium, which is more soluble and more toxic than DU. It was concluded that the major ecological hazard from expended uranium munitions will be chemical toxicity rather...

This study investigated the influence of uranium on the indigenous bacterial community structure in natural soils with high uranium content. Radioactive soil samples exhibiting 0.26% - 25.5% U in mass were analyzed and compared with nearby control soils containing trace uranium. EXAFS and XRD analyses of soils revealed the presence of U(VI) and uranium-phosphate mineral phases, identified as sa...