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  • Author or Editor: V. Jedináková x
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Abstract  

The use of appreciable H-D isotope effects in the infrared spectra of normal and deuterated salts of tri-n-octyl amine (TOAHX or TAODX, where X=Cl, Br, I, HSO4, NO3 and ClO4), the investigation of the chemical shift of the NH proton in NMR spectra, the results of chemical analysis (H2 O, D2 O acid) and the osmometrical data allow to explain some questions concerning the structure and to discuss the strength of the hydrogen bonds in associates TOAH+X and their hydration. From this comparison it follows that the strength of hydrogen bond in TOAH+X (TOAD+X) increases in the order of ClO 4 <HSO 4 <IBr<NO 3 <Cl. H-D isotope effects are discussed in the association of these salts.

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Abstract  

The technique for and methods of separation of products of nuclear fission play a major role in many stages of the nuclear fuel cycle. The extraction of these products from effluent solution after the processing of the burnt-up nuclear fuel is receiving considerable attention. Trivalent lanthanoides are usualy extracted together with Am(III) and their mutual separation is rather difficult.1–4 The extraction of lanthanoides with tertiary amines or quaternary ammonium salts involving the benzyl group as one of substituents has been studied in order to find the influence of the alkyl chain length on the extraction selectivity and capacity.3–5 Suitable extractants for the separation of Am(III) and Ln(III) from the acidic nitrate solutions were recommended. Using vapour phase osmometry and cryoscopy the association of these compounds was measured at 5.25 and 50°C allowing a rough estimation of medium association degree for the formation of the aggregates. The method of apparent molar volumes, supplemented by the spectrophotometric method, was used for identification of the chemical composition of the aqueous phase.

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Abstract  

This report identifies a number of mechanisms that retard radionuclide migration, describes methods that are used to study such retardation phenomena and evaluates the extent to which this methods may be used to diagnose radionuclide migration through various types of geologic media. A qualitative, quantitative and applicable basis for ion exchange modelling in clay have provided. Caesium and strontium are taken as a reference elements, and itsK d values obtained from both batch and diffusion experiments are explained and independently predicted by the model.

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Abstract  

Quality of several vitrified radwastes specimens was demonstrated on their hydrolytic resistance. The type of water corrosion mechanism and structural features were also elucidated. The time dependence of the corrosion process proved two subsequent mechanisms of water attack. The first stage is controlled by diffusion. Later the silicate matrix is damaged and its surface layer dissolved. Ultimately, the quality of glass is evaluated from the point of view of possible radioactivity releases.

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Abstract  

Solvation effects in the second organic phase in lanthanide extraction by benzyldialkylamines have been investigated by means of chemical analysis of the second organic phase, liquid chromatography, osmometric data and logarithmic analysis.

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Abstract  

The mechanisms of transport and retaidation processes, chemistry and migration behaviour of radionuclides of fission products and actinides in engineered barriers, especially bentonites, have been summarised. A “critical group of radionuclides” is proposed for thorough investigation of their retardation properties in natural sorbents. The evaluation of accessible data of retardation and transport parameters relevant for the conditions of underground deep repository to be projected is carried out from point of view their possible inclusion into a data-bank. The effect of solubilities and dissolution reactions, diffusion and sorption/desorption, complexation and variations in the aqueous phase composition, pH-value and oxidation-reduction properties and other phenomena on Kd values is discussed. Attention is devoted to thermodynamic modelling and its validation for evaluation of various phenomena in the buffer/backfill-ground water systems.

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Abstract  

The composition of degradation products of the radiolysis of benzyldibutylamine and benzene was identified by means of mass, NMR and infrared spectra, elementary analysis and gas liquid chromatography. The mass balance indicated that benzyldibutylamine was stable when irradiated by a medium-high dose of 143 kGy and its mass loss did not exceed 10% of the irradiated fraction.

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Abstract  

On the basis of 42 distribution dependencies, an analysis of the effect of the macrocomponent (Ln) on the extraction of the microcomponent (Am) by benzyldialkylamines and benzyltrialkylammonium salts has been made. Assuming the validity of DLn=f(c Ln 0 ) and DA m=f(c Ln 0 ), the power function of the general expression log D=–log P–q log c Ln 0 has been calculated, the constants have been determined for the equations applying to individual extraction systems. Their physical and chemical characteristics are discussed.

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Abstract  

The extraction of boric acid from a solution modeling radioactive waste has been studied. Different aliphatic alcohols were used as extractants. Factors affecting the distribution ratio of boric acid and the behaviour of some other components of the solution under conditions of boric acid extraction were investigated. The composition of species extracted was determined from distribution data of n-hexanol and H3BO3.

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Abstract  

Different aliphatic alcohols were tested for the extraction of boric acid from solutions modeling radioactive waste. In addition to distribution measurements, the number of molecules of extractant per H3BO3 molecule in the organic phase was determined assuming extraction by solvation. A method of activity coefficient evaluation in aliphatic alcohols-nonpolar solvent systems is proposed and hydration and solvation effects in these systems are investigated.

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