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Summary  

Sediment samples from the Romanian sector of the Danube River and the Black Sea coast were analyzed for Pu and Am. Three different ways of bringing the samples into solution were tested: acid attack, microwave digestion and alkaline fusion. A conventional anion-exchange resin was used to separate plutonium from other radionuclides and several variants were tried to improve the separation of americium. The preparation of thin sources for alpha-spectrometry was tested through electrodeposition and coprecipitation with Nd(III). Discussion and recommendations for the dissolution step, the americium separation and preparation of alpha sources are made.

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Abstract  

Similar distributions for 238U, 232Th, 226Ra, 210Po, 238,239,240Pu, 137Cs and trace elements were obtained in sediment samples collected along the Romanian sector of the Danube River and the Black Sea coast during 1994. The radionuclide and trace element accumulation in the investigated samples is discussed with respect to their geochemical behavior and the mineralogical structure of the samples. The latter, investigated by X-ray diffraction and cation exchange capacity of the same samples, proves to be an important factor in the selection of sampling sites for monitoring the pollution of river basins and the sea.

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Abstract  

Statistical tests were performed on the -spectrometry measurement data obtained during the last decade for the natural radionuclides40K,226Ra and232Th, in water samples collected from the Danube River, the Sava River and its tributaries, ground waters and artificial lakes. The lognormal radiopotassium distribution indicates a single statistical population. The presence of break points in the frequency distribution plots indicates that data for226Ra and232Th do not come from a single statistical population. The annual iongestion of40K,226Ra and232Th was calculated and expressed in Bq y–1.

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Abstract

The Oligocene clay units in the Budapest area along the new metro (subway) line show different properties than most others. They are denser and of greater strength than most of the unconsolidated ones. This paper provides an overview of their engineering geologic properties using nearly 4700 physical parameter data. These data were obtained from cores representing sampling intervals of the Kiscell Clay, on the Buda side of the Danube River. Seventeen engineering geologic parameters were used in the description of the clay. The parameter analyses show that the clay behaves as a soft rock rather than a soil.

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The results of seven new 40 Ar/ 39 Ar analyses and two K/Ar analyses of mineral separates of metamorphic rocks from the Transdanubian part (west of the Danube River) of the Tisza Mega-Unit is presented, and a review of the geochronological data available in the literature is given. Investigated rocks come from boreholes and include amphibolite facies rocks, mainly containing garnet, staurolite, kyanite, andalusite and sillimanite as index minerals. The investigated area covers 120 × 85 km in Transdanubia, including all tectonic units distinguished by previous authors. The 40 Ar/ 39 Ar spectra of the muscovites yielded fairly well-established plateau ages ranging from 307 Ma-312 Ma in all units. Similar muscovite Ar/Ar cooling ages of ca 310 Ma were obtained from other parts of Tisza Mega-unit east of the Danube, e.g. from the kyanite-sillimanite-bearing metapelites of the Villány-Bihar Subunit (Great Plain; Lelkes-Felvári et al. 2003).

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Abstract  

In order to use the wood building materials in dwelling construction, uranium content measurements were performed by one of the alpha or fission track methods. The investigated samples were tree and rush samples, collected from different Romanian sites, situated in the vicinity of zones with human radioactive activities, such as: Sapantza, Izvorul Izei (North Romania), Omer and Periprava (Danube River Delta). We have examined the U atom distributions in these samples in order to detect any U contamination due to radioactivity. For each analysed sample, two U track micromappings were obtained in the two track detectors which were put in intimate contact with the sample during reactor neutron irradiations. The obtained track micromappings were studied by optical microscopy. The U distribution and content measurement results are presented and interpreted according to the present norms referring to maximum permissible values of U in building materials in Romania.

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Abstract

The Oligocene Kiscell Clay is a widespread sediment of the Budapest region. The best-evaluated parts of the deposit are found along the new Metro (subway) line (Line 4) on the Buda side of the Danube River, where cores were cut. The geomechanical parameters of the Kiscell Clay were studied and evaluated using 481 samples from 41 cores. Nearly 5000 data were processed using different statistical parameters. The results of the statistical analyses are compared with previously-described soil-mechanical parameters; regional correlations of the mechanical properties of the Kiscell Clay are made by comparison with the results of previous analyses (Görög 2007a). There are significant discrepancies in the datasets of cohesion and uniaxial compressive strength, but other parameters show better correlation. In any case these analyses provide information for the engineering geologic design and planning for underground structures.

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Task of shipping operations control of the Gabčíkovo Project is to synchronize several requirements. These come from versatility of GAP and must meet with the following goals. The operation of GAP must be effective (maximization of the ship locks capacity, maximization of income from electricity production in hydropower plant); reliability of operation of the ship locks must not be limited or endangered by defects on technology parts of the ship locks caused by illegal parameters of water flow in the filling and emptying system; and shipping safety must not be endangered or limited by unsuitable parameters of river way (navigable depth below minimal shipping depths in ford sections caused by flow changes on Gabčíkovo Project and ships crushing into riverbed of the Danube river).

By taking these goals into account, it is possible, in general, to define operation of Gabčíkovo Project as complex multi-criteria optimization task with many technological, water management, energetic and environmental constrains. Standard approach in solving this problem includes elaboration of optimization or simulation model of Gabčíkovo Project operation. If mathematical description of problem does not exist, ‘classic’ expert control system management must be applied. Based on above stated criteria, most effective approach to this problem appears to be creating software application that combines both approaches.

In this case, expert control system of shipping operation on Gabčíkovo Project will be software application to model hydraulic links and hydraulic regimes (discharges, water levels and flow velocities) based on relevant inputs on the ship locks and whole section of the Danube river, that is affected by Gabčíkovo Project operation.

The paper describes possible optimization solution for achieving above mentioned goals. Architecture of proposed expert control system is described in the paper and the focus is mainly on analyzing suitability of heuristic optimization methods for solving above the stated optimization problems.

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Abstract  

The method for the determination of 90Sr which employs sodium hydroxide for the separation of strontium from calcium was further improved introducing the use of elevated temperatures. The results from 11-year study of background activity concentrations of 90Sr in different environmental objects in 100 km zone around Kozloduy Nuclear Power Plant (Bulgaria) are presented as an application of the analytical method. The measured mean values are as follows: air precipitation − 0.0015±0.0009 Bq(m2.d), tap water − 0.0017±0.0012 Bq/L, soil − 1.90±1.26 Bq/kg, grass − 1.54±0.80 Bq/kg, milk − 0.023±0.012 Bq/L and for the Danube river: water − 0.0046±0.0026 Bq/L, bottom sediments − 0.64±0.60 Bq/kg, algae − 1.99±1.56 Bq/kg. The calculated transfer coefficients (soil-grass) are in the range of 0.33–0.84. Between 2 and 5 times reduction in actual background activities of 90Sr is observed compared to 1972–1974.

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Abstract  

The possibility to obtain new information about the U/Th contamination using the patterns of the fission track micromapping is put into evidence. For the investigated samples, bed load sediments sampled from Danube river and Delta, fission track micromappings were obtained using the neutron-induced fission of the U and Th elements and the track registration of their fission fragments in muscovite track detectors. Utilising the optical microscopy, these micromappings were used both for U and Th content measurements and for studies of U/Th atom distributions. Considering the track micromapping pattern as a characteristic of the U/Th atom distribution in the analysed sample, and basing on the micromapping patterns that were previously obtained for the samples contaminated in the specific conditions, the authors were able to establish: (1) the presence of the contamination of the sediments in spite of the fact that the U/Th concentration values did not exceed the natural background values, (2) the solubility of the U/Th chemical compounds in the initial waste and (3) the presence of a succession of U/Th contaminations as well as the presence of the transported contamination.

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