Indirect Amplification Determination of Thorium by Atomic Absorption Spectroscopy

Thorium may not be determined by direct atomic absorption spectroscopy in flame media with appreciable sensitivity because of inefficient atomisation. Earlier papers from this laboratory have described indirect amplification procedures for similarly difficult elements e.g. niobium¹ and titanium² by atomic absorption spectroscopy· Madison and Guyon³ have developed a solution spectrophotometric procedure for thorium in which the heteropoly acid complex of thorium with phosphomolybdic acid is formed and reduced to the ‘heteropoly blue’. Strict adherence to time of addition of reagents is required in this procedure, and. it is necessary to effect an initial separation of the thorium from most other cations present in the sample.     

Simple method for calculating time dependence of individual radionuclide activities in decay series

A rapid method for calculating the time dependence of activities of individual radionuclides in genetically coupled decay series has been proposed. The method is based on the mathematical procedure, in which the matrix method is used for calculating a set of decay equations given in the vector form. The developed method is computerized and uses the modern Scilab software. This simple method eliminates certain drawbacks of older methods used previously for this purpose and is applicable to even solve calculations which are not easily treatable with the older methods. Some practical examples of such calculations are presented. Moreover, the new method is universal and it also enables a more general approach to the problem of the calculation of decay series in nuclear chemistry.      

Measurement and Modeling of Th Sorption onto TiO(2)

The sorption and desorption of Th onto TiO₂ (10 g/L) was studied as a function of pH (1–11), ionic strength (0.005–0.1 M NaCl, NaClO₄), thorium concentration (from 1 × 10⁻⁹ to 3 × 10⁻² M), and carbonate concentration (up to 10⁻² M) using ²³⁴Th tracer. The results indicate the reversible formation of an inner sphere complex with a strong pH dependence. No effect of the carbonate on sorption could be measured in the pH range investigated (5–10.5). The data were fitted with five different conceptual models (constant capacitance, diffuse layer, Stern, triple layer, and a nonelectrostatic model) using FITEQL. Different hydroxy complex surface reactions were tried, one at a time, varying the site density (1–12 sites/nm²). The reaction that provided the best fit depended strongly on the surface site density and the model used. To be able to fit a reaction to the pH-dependent data with the compact layer models, the effect of the electrostatic term had to be decreased by decreasing the site density below 5 sites/nm². None of the electrostatic models could be used to fit all of the isotherm data. The nonelectrostatic model could be used to reasonably fit both the pH-dependent and isotherm data.     

铀-钍混合燃料反应堆的可行性分析

分析了以铀为燃料的核电系统的弊端、钍燃料反应堆的理论技术依据和世界范围内钍燃料反应堆的研究状况。提出在我国开发利用钍资源,建立铀．钍混合燃料反应堆具有的独特优势,建议应加大钍资源开发人力物力投入,改变我国核电利用水平落后和钍资源流失之现状。Nuclear energy is a preferred option for electric power generation. The disadvantages of the current uranium-dioxide （UO2 ） fuel in nuclear power were presented and the reactor using the mixed thorium dioxide and uranium dioxide fuel （ ThO2-UO2 ） in the near future was foretold. A proposal to strengthen the research cooperation on the use of the thorium mineral resources in china was put forward.     

Masking Agents in Metal Titration with Edta Part IV - Thorium Titration in the Presence of Some Metals

Abstract

The authors studied the possible employment of various compounds containing sulfur as masking agents for divalent and trivalent metals, in the titration of thorium with EDTA. Reagents studied were thioglicolic acid, 3-mercaptopropionic acid, 2-mercaptoethanol, 2,3-dimercaptopropanol, BIS (2-hydroxy ethyl) dithlocarbamate, ethylxantate, thionalid, thiourea and thiosulfate.

The ones which proved more efficient were 2,3-dimercaptopropanol and BIS (2-hydroxyethyl) dithiocarbamate.     

Ab-initio theoretical analysis of thermal expansivity,thermal vibrations and melting of thorium

The thermal expansivity and mean-square thermal vibrational amplitudes were determined as a function of temperature for thorium from first principles total energy calculations using the full potential linearized augmented plane wave (FP-LAPW) method. The coefficient of thermal expansion determined from variation of theoretical potential energy with interatomic separation is ～1.427 × 10^?5 K^?1 as compared to an experimental value of 1.23 × 10^?5 K^?1. The mean-square thermal vibrational amplitudes determined as a function of temperature from the theoretically calculated volume-dependent Debye temperature agree well with experimental data derived form neutron diffraction measurements. The melting temperature of thorium, determined theoretically from the mean-square thermal vibrations and the Lindemann rule for melting, is 2234 K, as compared to the reported experimental value of 2021 K.     

Bioakkumulation von UO2 2+- und Th4+-Ionen aus Abwässern

Abstract

Using different algea types the bioaccumulation of UO₂ ²⁺ and Th⁴⁺ ions from experimental residual wastes of nuclear facilities was investivated. The retaining degree of these ions on microbiological sorbents decreases as: Scenedesmus quadricauda > Porphyridium cruentum > Spirulina platensis > Calothrix sp.2 > Calothrix sp.1 for UO₂ ²⁺ and Porphyridium cruentum > Spirulina platensis > Scenedesmus quadricauda for Th ⁴⁺. For the same algae it was observed that the retaining degree is much higher for UO₂ ²⁺ than for Th⁴⁺, probably due to the different linking degrees of hydrolysed species of these ions on the macromolecular compounds of the living cells through the chemical functional groups.     

Major,Minor, Trace Elements and Natural Radioactivity Content by NAA of Some Materials

By using 14 MeV neutron flux of 3.5 × 10¹⁰ n/cm² · s, the activities of the activated nuclides in both ferrosilicon alloy (from Kima-Aswan Company) and black sand samples (from the mouth of Damietta, North of Egyptian Delta), were measured. The rate dose of natural gamma-activities arising from Th-232 in the black sand area was calculated.     

Ein α-Spektrometcr für Untersuchungen mit Umweltnukliden

Es wird ein einfaches α-Spektrometer mit einem Halbleiterdelektor beschrieben, das für die Messung von Umweltnykliden entwickelt wurde. Zur Anpassung an unterschiedliche Meßaufgaben kann die Meßgeometrie durch Variation des Präparat-Detektor-Abslandes und durch Einbau von Blenden verändert werden. Dabei ist eine gewählte Meßgeometrie mit hoher Genauigkeit reproduzierbar. Die Nachweisgrenze des α-Spektrometers beträgt bei einer Meßzeit von 4 · 10⁵ s etwa 2,3 mβq, das entspricht 0,18 μg U bzw, 0,55 μg Th.