Effect of accelerators on thoria based nuclear fuels for rapid and quantitative pyrohydrolytic extraction of F? and Cl? and their simultaneous determination by ion chromatography

Pyrohydrolysis is a fast, reliable and convenient method for the decomposition of solid refractory samples. Thoria based mixed oxide nuclear fuels requires more than 1,200?°C reaction temperature to lose its structural integrity so as to release the halides. In the present paper, we report WO₃ accelerated pyrohydrolytic extraction technique for the separation of F^? and Cl^? from thoria based fuels along with the feasibility of using MoO₃ and V₂O₅. The mechanism of extraction has been investigated in detail using X-ray diffraction and recovery studies. ThO₂ along with its halides undergo high temperature solid state reaction with WO₃ forming Th(WO₄)₂ and releasing the halides for their subsequent hydrolysis. The quantification was carried out by ion chromatography with suppressed ion conductivity detection. The average recoveries of the spiked samples for F^? and Cl^? were 93?C99%. The method was successfully applied for simultaneous determination of F^? and Cl^? in thorium based nuclear fuel samples at 950?°C.     

Minimum error solutions of boundary layer equations

The minimum error solutions of boundary layer equations in the least square sense have been studied by employing the Euler-Lagrange equations. To test the method a class of problems,i.e., boundary layer on a flat plate, Hiemenz flow, boundary layer on a moving sheet and boundary layer in non-Newtonian fluids have been studied. The comparison of the results with approximate methods, like Karman-Pohlhuasen, local potential and other variational methods, shows that the present predictions are invariably better.     

Ni(NO3)2·6H2O/I2/water: A new,mild and efficient system for the selective oxidation of alcohols into aldehydes and ketones under sonic condition

A new, simple, efficient and rapid method for the oxidation of alcohols into respective aldehydes and ketones by Ni(NO₃)₂·6H₂O/I₂/water system under ultrasonic irradiation is reported. The process is mild and inexpensive; the yields are high and the reactions go to completion within 2–7 min.     

Term isotope shift of high lying odd and even energy levels of Nd II

The isotope shifts of the odd and even parity energy levels of singly-ionised neodymium (Nd II) have been evaluated using the measurements carried out in more than 300 spectral lines of Nd II in the region 3290–5820 Å. Term shift, ΔT (¹⁴⁴Nd-¹⁵⁰Nd), is being reported for 23 low even and 15 high lying even parity levels of Nd II. ΔT for a level of 4f ³6s6p configuration and 8 even levels between 36892 and 43212 cm^-1 are being reported for the first time. ΔT values of 151 high lying odd parity levels are being reported and compared with some of the available earlier reported values. ΔT values of 47 odd parity levels are being reported for the first time, most of which are based on our isotope shift studies in UV region. The electronic configuration assignments to energy levels of Nd II by earlier workers are discussed on the basis of present ΔT values. Electronic configurations to some of the unclassified high lying odd levels have been suggested; the levels with ΔT (144–150) between 300mK and 380mK are assigned to 4f ³5d6s configuration whereas a level with ΔT value of 60mK to 4f46p configuration.     

A floating spherical gaussian orbital model of molecular structure. XII. Analysis of energy terms affecting the geometry of the water molecule

The energy terms arising in the water calculation by the FSGO method are analyzed as a function of the bond angle in order to gain insight into the reasons for the particular equilibrium configuration. The analysis is made in terms of symmetrically orthogonalized orbitals so as to exclude three- and four-orbital electron repulsion terms.     

Thermodynamics of adsorption (as a function of temperature and pressure) of N2 and CO2 on graphites

Summary A quantitative treatment, coupled with critical qualitative considerations, pertaining to the study of thermodynamics of adsorption of N₂ and CO₂ on different graphite samples, through the evaluation of the film pressure, as a function of temperature and pressure, is presented. The . determination of the adsorbent specific surface areas is affected through the graphic manipulation of the Langmuir adsorption equation utilizing data adopted from literature, and the values are then computed by employing the Gibbs adsorption equation by making use of the areas under them-lnP curves. The results deduced are discussed specifically in terms of as related to the nature of the adsorbents, the magnitude of the calculated thermodynamic functions and the specific surface areas for the individual adsorbents.

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Zusammenfassung Die Arbeit bringt eine thermodynamische Studie der Adsorption von N₂ and CO₂ an verschiedenen Graphitpräparaten. Grundlage der Betrachtung ist der Filmdruck als Funktion der Temperatur und des Druckes. Die Bestimmung der spezifischen Oberfläche des Adsorbens wird beeinflußt durch die graphische Behandlung der Langmuirschen Adsorptionsgleichung. Es wurden Literaturwerte adoptiert und-Werte nach der Gibbsschen Adsorptionsgleichung berechnet. Die abgeleiteten Ergebnisse werden diskutiert und zur Natur des Adsorbens, zur Größenordnung der berechneten thermodynamischen Funktionen und zur spezifischen Oberfläche der einzelnen Adsorbentien in Beziehung gesetzt.

     

Selective adsorption of cerium on activated charcoal from aqueous electrolyte solutions

The adsorption of cerium on activated charcoal has been studied as a function of shaking time, pH, concentration of adsorbate and temperature. The adsorption of cerium obeys Freyndlich and Langmuir isotherms. The influence of different cations and anions on cerium adsorption has been exmined. The adsorption of other metal ions on activated charcoal has been studied under specified conditions to check its selectivity for cerium adsorption. Consequently, cerium was removed from a mixture containing Ce, Ba, Sr, Ru, Cs, Cr, Nd, Pr and In. About 99% of the adsorbed cerium on activated charcoal can be recovered with 3M HNO₃ solution. A wavelelngth dispersive X-ray fluorescence spectrometer was used for measuring the cerium concentration.     

Isotope shifts in spectral lines of Yb+ in 322-615nm region and term shifts of odd and even parity energy levels of Yb II

Isotope shift Δσ(¹⁷²Yb - ¹⁷⁶Yb) has been measured in 79 classified lines of Yb II in the region 3225-6155 Å. Earlier studies provide isotope shift data in just six lines of Yb II. Term isotope shift ΔT (¹⁷²Yb-¹⁷⁶Yb) have been evaluated for 38 even and 30 odd parity levels of Yb II, using the present isotope shift data. The ΔT values have been discussed and correlated with the purity of the configuration assigned to an energy level, which enabled to check the reported eigenvector percentages of different configurations for some of the levels of Yb II. ΔT values of different levels resulting from J_IL_II couplings are also discussed.     

Activation cross-sections for209Bi(n,α)206Tl reaction

Cross-section for²⁰⁹Bi(n, α)²⁰⁶Tl reaction at incident neutron energies 340±150 keV and 575±235 keV have been measured to be 1.26±0.18 μb and 1.55±0.23 μb, respectively. The activation technique was used for measuring the cross-sections. These values have been compared with theoretical values based on Hauser Feshbach Statistical Model.