Non-destructive determination of nuclear fuel burn-up by measuring the gamma radiation of fission products in irradiated uranium oxide

The burn-up of²³⁵U was determined in two uranium oxide samples (0.713 and 89.9%²³⁵U in mixture) irradiated simultaneously with a cobalt monitor, from the amounts of⁹⁵Zr,¹⁰³Ru,¹³⁷Cs,¹⁴⁰Ba and¹⁴⁴Ce obtained by measuring the intensities of the corresponding gamma radiations. The samples were irradiated for 23 days, and the fission products were measured after cooling for 100 days, nondestructively, by means of a Ge(Li) spectrometer. The integrated neutron flux was determined by measuring the produced⁶⁰Co in the cobalt monitor. The burn-up in both samples was determined by measuring the intensity of eight gamma energies (0.5–1.6 MeV). The determined values are in good agreement. The standard deviation of the mean value ( ) is 5%. The atom per cent fission of²³⁵U in both samples, calculated according to , differs by 1%. The measured σ _f for²³⁵U is in good agreement with the data reported in the literature.     

Photon-induced K-shell X-ray intensity ratio for elements with 74≤Z≤92

The K-shell X-ray intensity ratios and for W, Au, Tl, Pb, Bi, Th and U have been measured at a photon incident energy of 121.9 keV from⁵⁷Co radionuclide. A comparison between the experimental results and the theoretically calculated values shows that the experimental results are, in general, higher than the theoretical values. To the best of our knowledge, the measured intensities are reported for the first time.     

Systematics of nuclear charge distribution in fission the ZP model

An extension of the conventional Z_P model has been used with data for ten fission reactions and the method of least-squares for derivation of parameters that describe the nuclear charge-distributions. Data for light and heavy fission products for each reaction were treated together by consideration of the complementarity of average mass numbers of precursors (A′_L+A′_H=A_F). This treatment gave calculated yields that are essentially equal for complementary elements (Z_L+Z_H=Z_F). The parameters determined, , the Gaussian dispersion width parameter, a linear function of Δ_Z=|Z_P-A′(Z_F/A_F)|, Z_P being the Z at maximum of the curve, and and , the even-odd proton and neutron yield enhancement factors, represented most data (A_H⋟130–150 and the complementary light A's) moderately well, better than did oscillating functions of and Δ_Z. The values were found to be approximately constant (0.48 to 0.62) and, generally, to increase with the average number of neutrons emitted, . The Δ_Z values at A′=140 were in the range of 0.42 to 0.50, and the slopes, ∂Δ_Z/∂A′_H, ranged from 0.0 to 0.03. The factor was found to be several times larger than the factor and to decrease with increasing excitation energy and with A and/or Z of the fissioning nucleus, as has been reported previously. The adequacy of the Z_P model for representation of data and for prediction of yields in the high-yield mass-number regions mentioned above are discussed, and the large uncertainties that are involved in extrapolating the model to near symmetric or to very asymmetric mass and charge divisions are pointed out.     

Calculation of average L shell fluorescence yields for the elements with 25≤Z≤101

Average L shell fluorescence yield , average L shell Auger yields and the total L shell X-ray fluorescence (LXRF) cross sections (σ _L ^x ) at 30 keV have been calculated theoretically for the elements with 25≤Z≤101. These calculated values have been compared with the other experimental and theoretical values.     

Substoichiometric exchange extraction of tantalum and gold with tetraphenylarsonium

The conditions for substoichiometric exchange extraction in the system have been investigated in order to establish the feasibility of substoichiometric separation of tantalum and its determination by activation.     

Effect of dissolved oxygen on the inactivation of bacteriophages in water by gamma radiation: Important role ofH\dot O_2 radicalsradicals

The inactivation of bacteriophages by -radiation was studied in 0.1M Na phosphate buffer and in deionized water in the presence and absence of dissolved oxygen. From the results obtained it is possible to make conclusion that radicals /which are formed in radiolysis of water in the presence of oxygen/ have a marked inactivating effect on bacteriophages, but in the simultaneous presence of radicals an inactivation takes place between them.     

Alkali metal ion-selective electrodes based on relevant alkali metal ion doped manganese oxides

Potentiometric properties of manganese oxides doped with alkali metal ions (Na⁺, K⁺, Rb⁺ and Cs⁺), which were prepared by heating mixed solutions (starting solution) of each alkali metal and Mn²⁺ ions, were examined. Electrodes based on mixed phases of Nao₄₄MnO₂/Mn₂O₃ and hollandite KMn₈O₁₆/M₂O₃ found by X-ray powder diffraction (XRD) exhibited Na⁺- and K⁺-selective responses with a near-Nernstian slope, respectively, when the molar ratio of alkali metal ion to Mn²⁺ ion in the starting solution was 0.1. When no alkali metal ions were added in the manganese oxide films, no significant potentiometric response was observed to any alkali metal ions. The selectivity coefficients of these electrodes were = 6.7 × 10^–2, = 7.1 × 10^–3, < 9 × 10^–4 and < 9x 10^–4 for the Na_0.44MnO₂/Mn₂O₃, and <4 × 10^–4 <4x 10^–4, =60 × 10^–2 ×10^–4, < 4 × 10^–4, for the KMn₈O₁₆/Mn₂O₃, respectively. Electrodes based on manganese oxides made from mixed solutions of Rb⁺/Mn²⁺ and Cs⁺/Mn²⁺ also responded to the respective primary ions, that is, Rb⁺ and Cs⁺ ions, although XRD patterns for the manganese oxides thus made did not show any peaks except for Mn₂O₃ (bixbyite); it was concluded in these cases that some amorphous type manganese oxides were formed in the Rb⁺/Mn²⁺ and Cs⁺/Mn²⁺ systems and they responded to the respective ions. Conditioning of these electrodes in an aerated indifferent electrolyte solution, 0.1M tetramethylammonium nitrate (TMA-NO₃), for relatively long time, typically more than 2 hours, was found to be a prerequisite for near-Nernstian response to the respective alkali metal ions. During this electrode conditioning, vacant sites (template) suitable in size for selective uptake of primary ions seemed to be formed by releasing the doped alkali metal ions from the solid phase into the adjacent electrolyte solution accompanying oxidation of the manganese oxide film.     

Interferences in the determination of trace elements in high-purity tin

Reactor neutron activation analysis of antimony, indium and cadmium in high-purity tin is interfered with by nuclear reactions on the tin matrix. For a number of interfering reactions the cross-sections were determined. The following results were obtained:¹²²Sn(n,γ)^123mSn:σ_th=0.145 barn, I=0.79 barn;¹²²Sn(n,γ)¹¹³Sn:σ_th=0.52, I=25.4 barn;¹¹²Sn(n, 2n)¹¹¹Sn: microbarn;¹¹⁸Sn(n, α)¹¹⁵Cd: microbarn; and¹¹⁴Sn(n, p)^114m1In: microbarn.     

A method for experimental determination of effective resonance energies related to (n, γ) reactions

When making use of some single comparator or absolute standardization methods in reactor neutron and in epicadmium neutron activation analysis, the knowledge of the effective resonance energy ( ) is essential to correct for the effect of the nonideal epithermal flux distribution on the analysis result. can be calculated from neutron resonance data, but when these are incomplete, not accurate or even not known at all, experimental determination should be considered. Such a method, providing both and the resonance integral to 2200 ms^–1 cross-section ratio (Q_O), is described in this paper. Results are given for 11 isotopes.     

A generalized separation reaction scheme for assessment of the radioanalytical method of concentration dependent distribution

For the assessment of the analytical error of concentration dependent distribution (CDD), complex-forming separation reaction was proposed in a generalized form of equilibrium , where n is the effective stoichiometric coefficient, i.e. the difference of mean ligand numbers and <n> of a mixture of complexes of analyte M with reagent L in the respective groups (distinguished by bars above the symbols) of the separation system. Calibration curve is derived from measurement of gross activity of complexes, A=A(ML_<n>) and . Theoretical relative error is expressed as a product of three terms, x/x=f₁f₂f₃. The first term f₁ depends on the degree of isotopic dilution, and the recommended ratio of amounts of nonradioactive (x) and radioactive (y) substance M is x/y(1;4). The second term f₂ depends first of all on the slope of distribution ratio (yield of separation ) vs. the analyte; reagent ratio, n(Z+1)/T. The form of slope is analyzed on the basis of the generalized separation reaction. Optimal conditions were discussed from this point of view and the ideal case is at f₂=1. The third term f₃ depends on the activities A and , i.e. on the distribution ratio, sample volumes, and the manner of counting. The ideal ratio of sample activities is A= and the optimal interval (0.2;0.8) is suggested     

Effect of solvent on the partial molal volumes and heat capacities of nonelectrolytes

Group contributions to in seven solvents and to in three solvents have been tabulated. The variation of group parameters is discussed in terms of the solvent compressibility coefficient, _T. The scaled particle theory (SPT) is used to calculate cavity contributions to and C _p2 ^o . Interaction contributions are obtained from the cavity terms and and values estimated through the additivity schemes. values are more sensitive to solute-solvent interactions than in water and less sensitive in methanol. The SPT results for heat capacities support the concept of structural promotion by hydrophobic solutes in water.     

Mass transfer in shell-core inorganic TIP1 ion exchanger

The ion exchange processes of (OAc^–) and (OAc^–) proceeding in shell-core inorganic ion exchanger Ti (HPO₄)₂·1/2H₂O has been studied and the diffusion equation whose boundary conditions are satisfied by a shell-core model was solved. Based on the equation solved and experimental data, the diffusion coefficients corresponding to the exchange process (OAc^–) and Li⁺–H⁺ (OAc^–) at 17°C are found to be 7.7×10^–9 and 6.2×10^–8 cm² s^–1 and the activation energies 3.4×10⁴ and 5.0×10³ J mol^–1, respectively. Compared to the gel type of styrene-divinylbenzene strong acid exchanger with 20% cross linking, it can be concluded that the rate of or exchange is 3.5 times faster than that in the organic exchanger.TIP was obtained from the Salt Lake Institute of the Academy of Science of China.     

The standard transported entropy of chloride ion in H2O and D2O

Transported entropies of the chloride ion, , in H₂O and in D₂O at 25°C and at concentrations ranging from 0.001 to 0.04m have been determined from the measurements of the steady-state (final) thermoelectric powers of the silver-silver chloride thermocell. Experimental data was extrapolated to infinite dilution to obtain the standard transported entropy . The concentration dependence of is examined and the solvent-isotope effect on the transported entropy is investigated. Thermodynamic data on the entropy of transfer of chloride ion from H₂O to D₂O is used to estimate the difference of the standard ionic entropy of transport in H₂O and D₂O for chloride ion.     

Effect of charge on the standard partial molar volumes and heat capacities of organic electrolytes in methanol and water

Previously developed additivity schemes for nonelectrolytes have been used to estimate and for tetraalkyl and tetraphenyl methanes in methanol and water. Corrections have been applied to the thermodynamic values of these model compounds to account for a variation in size of the central atom, and these were used to ascertain the effect of charge on and of alkyl and phenyl quaternary ions having N, P and B as central atoms. Investigations of R₄NBr, (R=methyl to heptyl) salts show that the charge effect on and of R₄N⁺ ions is large and relatively independent of ion size suggesting that the solvent molecules penetrate the ions. The ability to estimate and of the quaternary ions in the bromide salt solutions has made it possible to make ionic assignments with some confidence; (Br^–) has been evaluated as 19.7±2 and 30.2±7 cm³-mol^–1 and (Br^–) as –83±7 and –68±30 J-K^–1-mol^–1 in methanol and water, respectively. The use of organic ions for making ionic assignments of and is critically examined and comparisons with other assignments are made. The scaled particle theory is employed to divide the heat capacities of electrolytes into cavity and interaction contributions.     

Oscillatory variation in yields of I2 and the reactivity of γ-irradiated TiO2 in KI solution

The reactivity of preheated and -irradiated TiO₂ was observed in KI solution by studying the kinetics of liberation of I₂. The rate of the reaction was found to be low. species proposed on the surface of oxide probably dissociate into . surface sites which oxidize I^– ions to produce free I₂. During irradiation and are produced which are reducing in nature and therefore very low yields of I₂ are observed for low -doses. In further irradiation the reformation of –O–O–, peroxy linkages is proposed hence the observed higher yields. All the processes ultimately lead to an oscillatory variation in yields of I₂ with -doses.     

Critical evaluation of the effective resonance energy concept and the epithermal neutron spectrum shape-factorα for reactor NAA purposes

The epithermal reactor neutron spectrum shape-factor, and the associated effective resonance energy for a given nuclide, are examined theoretically in great detail. First the necessity, meaning and importance of the choice of a reference neutron energy in a non-ideal spectrum (0) are explained. Next, the definition and practical calculation of are discussed, showing that the relation between the reasonance integrals in ideal and non-ideal spectra cannot be described adequately by two independent parameters and . The exact meaning of the logarithmic expression defining an independent of is clarified, its limits of validity are established as a function of and, as a result, it follows that relatively large systematic errors on can be introduced by its use. It is shown that is dominated by the first lowest resonance energies for a given nuclide, making its vulnerability to literature updates of resonance parameters almost equal to those of individual resonances. The effect, on the epithermal and total activation of specific nuclides, of large systematic and statistical errors on and, is calculated for a series of nuclides (different I₀/₀ and ) and irradiation facilities (different and _the), and represented graphically.Finally, the effect of important errors on and is calculated for final NAA results in terms of concentrations, botained by a comparator technique based on the¹⁹⁷Au reference nuclide. Conclusions are drawn concerning the impact of the foregoing on the usefulness of comparator type reactor NAA as an alternative to classical NAA using multi-element standards.     

Laser-induced fluorescence study on the interaction of Eu(III) with polycarboxylates

Laser-induced fluorescence spectroscopy was applied to obtaining hydration structure of Eu(III) complexes with synthetic polycarboxylates of poly(acrylic acid), poly(maleic acid), poly(methacrylic acid), and poly(a-hydroxyacrylic acid). Dependence of (the number of water molecules in the first coordination sphere of Eu(III) ion) on pH and supporting electrolyte concentration was obtained for these complexes. The spectroscopic results show that Eu(III) is surrounded by the “cage” of polycarboxylate ligands. The pH-induced transition in conformation of poly(methacrylic acid) ligand was clearly observed in the plot vs. pH.     

Komplexverbindungen von Germaniumsäure mit ÄDTE und ÄDTE-Analogen, 1. Mitt.: Äthylendiamintetraessigsäure

Zusammenfassung Die Verbindung GeY · 2 H₂O wird nach einem Verfahren dargestellt, das die Verwendung von flüchtigem GeCl₄ vermeidet und direkt von Germaniumsäure-Lösungen ausgeht. Der Komplex, der analysenrein anfällt, wird thermogravimetrisch untersucht. In Wasser gelöst, erweist er sich als einbasige Säure, H[Ge(OH)Y]. Die Dissoziationskonstante der komplexen Säure wird potentiometrisch bestimmt:K _c =3,99 · 10^–3 (pK _c =2,40). Die Stabilitätskonstanten der komplexen Säure sowie des komplexen Anions werden ermittelt: =6,27 · 10⁴ (log =4,80); =3,34 · 10⁴ (log =4,52) (25°C; Ionenstärke 0,1m).

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The complex compound GeY · 2 H₂O is prepared directly from germanic acid solutions, avoiding volatile GeCl₄. It has been submitted to thermogravimetric analysis. Dissolved in water, it proves to be a monobasic acid, H[Ge(OH)Y]. The dissoziation constant of the complex acid is determined potentiometrically:K _c =3,99 · 10^–3 (pK _c =2,40). The stability constants of the complex acid as well as of the complex anion are evaluated: =6,27 · 10⁴ (log =4,80); =3,34 · 10⁴ (log =4,52), at 25°C; ionic strength 0,1m.

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Mit 4 Abbildungen

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Herrn Prof. Dr.J. W. Breitenbach zum 60. Geburtstag gewidmet.     

Cesium, strontium, europium(III) and plutonium(IV) complexes with humic acid in solution and on montmorillonite surface

The effect of Aldrich humic acid (HA) on the mobility of¹³⁷Cs,⁸⁵Sr,¹⁵²Eu and²³⁹Pu radionuclides was studied in Ca-montmorillonite suspensions. Verified 2-sites-2-species (2s2s) models correspond to an intensive interaction of all elements with humificated surface, what is in a remarkable contrast with the weak complexation of cesium and even strontium in solutions — the neutral ligand interaction constants β (l/mol) are log β<−9.9 and 7.56±0.21 for Cs and Sr, respectively. The result for europium complexation in solution, log β=12.49±0.18 is in a good agreement with literature data. For plutonium(IV) not only a high proton competitive constant in solution was obtained, log β β=(−0.67±0.32)+3pH, but also a strong chemisorption, which at high concentrations of humic acid (above 0.05 g/l) indicates the formation of bridge humate complexes of plutonium on the humificated surface. Logarithms of heterogeneous interaction constants ( ₂₄ l/g) of the elements with surface humic acid are 4.47±0.23, 4.39±0.08, and 6.40±0.33 for Cs, Sr, and Eu(III), respectively, and the logarithm of the proton competitive constant ( ₂₄, l/g) for Pu(IV) −3.80±0.72. Distribution coefficients of humic acid and metal humates between 0.01 g HA/l solution and montmorillonite were derived as logK _d(AH)=−1.04±0.11, logK _d(EuA)=1.56±0.11 and logK _d(PuA)=2.25±0.04, while the values for Cs and Sr were obtained with very high uncertainty. Speciation of the elements on montmorillonite surface is illustrated as a function of equilibrium concentration of humic acid in solution and of pH.     

Preferential solvation in three component systems: Evaluation of Kirkwood-Buff parameters

The extent of local excess or deficiency of a component solvent near the solute in a mixed binary solvent has been calculated using the Hall formalism for the Kirkwood-Buff equation. The possibility of calculation of the two solute-solvent Kirkwood-Buff parameters using the values is discussed. A model calculation using literature data for preferential solvation in mixed binary solvents is presented. The solute-solvent and solvent-solvent interactions and the relative size of the solvents are also shown to be relevant factors in determining the values.