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The kinetics of thermal decomposition of iron(II) sulphate hexa- to monohydrates, as well as the hydroxy- and oxysulphates of iron(III), are presented and discussed. The results confirm that the final intermediate that decomposes to iron(III) oxide and sulphur trioxide during the thermal decomposition of any hydrate of iron(II) sulphate is the oxysulphate, Fe2O(SO4)2.

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Abstract  

The intermediate level liquid radioactive wastes (RAW) isussed from nuclear power plants have high salt contents ca 200 g·dm–3, the pH of liquid RAW being 12.5–13.7. A convenient method for separation of cesium under these conditions is solvent extraction with substituted phenols. For this purpose weere tested antioxidants produced in Czechoslovakia: AO 2246 [2,2-methylene-bis-(4-methyl-6-tertbutyl)phenol]; AO 4 [2-tertbutyl-4-(2-phenylpropyl)phenol]; AO 4K [2,6-ditertbuty-4-methylphenol]; AO 301 [2,2-methylene-bis-(4-{2-phenylpropyl}-6-tert-butyl)phenol]; and one antioxidant imporoted from Japan—NOCRAC 2246. This antioxidant is equivalent to AO 2246. After the first experiment it was found that the extraction efficiency for antioxidants AO 4 and Ao 301 is very low and the following experiments were made with AO 2246 (NOCRAC 2246) and AO 4K. Some effects on extracton as, pH of water phase, influence of diluent, influence of concentration of antioxidants, extraction time, were studied. The best results gave antioxidant NOCRAC 2246 in nitrobenzene, the extraction efficiency was 92.3% with pH 13.23.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: P. Ormai, A. Fritz, J. Solymosi, I. Gresits, E. Hertelendi, Z. Szúcs, N. Vajda, Zs. Molnár, and P. Zagyvai

Abstract  

In the execution of disposal of low and intermediate level radioactive wastes, it is important to evaluate accurately the kind and quantity of each radionuclide in the wastes. For such an evaluation, correlation of non-gamma-emitting nuclides based on gamma-emitting nuclides is recommended and regarded as a practical method. This method necessitates a completion of a highly accurate and reliable nondestructive assay system of gamma-emitting nuclides for practical use. In 1992, in support of the new waste disposal program in Hungary, Paks NPP initiated a waste characterization program to determine the radiological properties of its radwastes. A segmented gamma scanning system has been set up to measure the gamma-emitting nuclides in 200 litre low level drums following in-drum compaction. In the framework of the program a radiochemical analysis sub-program was started to determine the long-lived non-gamma emitting radionuclides, mainly those listed in the US regulatory document (10CFR61). The radionuclides of interest have been3H,14C,90Sr,55Fe,59Ni,99Tc,129I and TRUs. Sample preparation techniques and measurement methods have been selected and used. Newly developed or adopted methods have been tested on real liquid radwaste streams such as concentrates, ion-exchange resin and sludge. The measurements taken so far have revealed brand new information and data on radiological composition of waste of WWER-type reactors. In the next stage of the characterisation program attempt will be made for providing correlation factors between the gamma and non-gamma-emitting radionuclides in different waste streams. Short description of the methods and results on waste inventory are given by highlighting the problem areas.

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Abstract  

The distributions of 210Po and 210Pb in the intermediate layer (400–2000 m) of the northwestern North Pacific were determined to elucidate the export flux of particulate matter. 210Po generally showed depletion relative to 210Pb in the intermediate layer, suggesting that 210Po was scavenged by particles. Because the removal rate constants of 210Po in the western region were higher than those in the eastern region and this trend coincided with that of the particle fluxes in the surface layer, the export production in the surface layer was assumed to influence the particle flux in the intermediate layer of the northwestern North Pacific.

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Abstract  

The triazene derivative of N-isopropylamphetamine XI, has been prepared in seven steps from amphetamine, as a new intermediate which is readily converted to N-isopropyl-p-iodoamphetamine /XII/. XI makes now possible the simple, rapid and regiospecific synthesis of /125I/- or /123I/-XII direct before the application.

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Abstract  

Gamma-irradiated at 77 K 1,4-dioxane and morpholine have been studied by ESR-spectroscopy. C-O bond dissociation is the main process in the γ-radiolysis of 1,4-dioxane and a significant contribution of −CH−CH=O radicals to the experimental spectrum is observed. Both H-atom abstraction and the cleavage of the ring seems to occur at low temperature γ-radiolysis of morpholine. The paths of formation of intermediates in cyclic ethers γ-irradiated at 77 K are discussed.

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Abstract  

Selective efficient method have been for separation of palladium by strong basic anion exchangers IRA-410 and IRA-900 from intermediate radioactive nitrate medium. The different conditions for exchange behaviour of palladium from [ILLW] solutions containing numbre of elements were investigated by batch technique. Selective recovery of palladium from the [ILLW] solution was achieved using column technique. The elution of palladium was carried out via reduction with formic acid where the rate of the reduction process was increased by decreasing the formic acid concentration till 50% followed by dissolving the separated palladium by nitric acid.

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Abstract  

Separation of palladium by strongly basic anion exchangers IRA-110 and IRA-900 from intermediate radioactive liquid waste in chloroacetic acid/nitrate medium containing thirteen elements have been achieved. Different conditions have been studied, the effect of NaNO3 as salt content, chloroacetic acid and hydrogen ion concentration have been investigated. Selective recovery of palladium from the [ILLW] solution was achieved using the column technique. The selectivity increased by using chloroacetic acid/nitrate than in nitrate medium. The elution of palladium was carried out via reduction with formic acid where the rate of the reduction process was increased by decreasing the formic acid concentration till 50% followed by dissolving the separated palladium by nitric acid.

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Abstract  

A methodology for the determination of 90Sr in low- and intermediate-level radioactive wastes from nuclear power plants is presented in this work. It is a part of a methodology developed for the sequential radiochemical separation of radionuclides difficult-to-measure directly by gamma spectrometry in these radioactive wastes. The separation procedure was carried out using precipitation and extraction chromatography with Sr Resin, from Eichrom and the 90Sr was measured by liquid scintillation counting (LSC). Optimum conditions for the pretreatment, separation and LSC measurements were determined using simulated samples, which were prepared using standard solutions and carriers. The procedure showed to be rapid and achieved a good chemical yield, in the range 60–90%, and a detection limit of 6.0 × 10−4 Bq g−1. The method was also tested by participation in a national intercomparison program, with aqueous samples, with good agreement of results.

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Abstract  

Safety assessment of low and intermediate level waste (LILW) repositories requires the understanding of radionuclides sorption–desorption mechanisms, mainly the degree of interaction between radionuclides and mineral surfaces. Among the different radionuclides that are part of the Portuguese radwastes’ inventory 137Cs is one of the most important from the radiological point of view due to its high radiotoxicity. The clay component of natural geomaterials termed rañas, originated from an area located in the NE Mainland of Portugal, was studied for their potential as effective barriers. These geomaterials (grains-size fractions <63 μm, <36 μm) were characterized in terms of cationic exchange capacity (CEC), frayed edge sites (FES) and radiocaesium interception potential (RIP). Organic matter content and pH were also determined. The fractions were mineralogically analyzed by X-ray diffraction and by instrumental neutron activation analysis (INAA) for chemical elemental composition. Smectite (montmorilonite), illite, kaolinite were identified. The capacity of FES is related to the samples granulometry as opposed to what was observed for CEC and RIP. The behavior of rañas was not similar for all samples which may be related to differences in mineralogy. Future studies with regard to the behaviour of radiocaesium are expected to clarify the possible application of these geomaterials as liner/backfill/buffer for a LILW repository.

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