Determination Of Gross Alpha Activity Research Articles

Study of the radiological impact caused by the extraction of the residue of a dicalcium phosphate industrial plant

In recent years, a decontamination project has been under way to remove the polluted sludge on the riverbed of the Ebro river, particularly in the area of Flix (Tarragona, Spain). This project started in 2011 and consists of the removal of the sludge and its treatment in a process that will eventually restore the river to its natural conditions. The sludge is a product of the historical dumping of contaminants by a chemical complex situated next to the river, and it contains a range of contaminants, such as heavy metals, semi- and volatile organic compounds, and radionuclides. Downstream of the complex, in the town of L’Ampolla, a drinking water treatment plant (DWTP) is located. This plant collects the water from the Ebro river and, after potabilisation, the plant supplies drinking water to the population of southern Catalonia. Due to the possible presence of radionuclides in the river water, it was considered important to monitor and control the radioactivity parameters regulated under current legislation for water consumption. For this reason, in this study, our aim is to evaluate if the decontamination work carried out in Flix has any effects on the radioactivity levels of both Ebro river and treated water, by means of the determination of gross alpha activity, gross beta activity and a group of gamma emitter radionuclides at three different sampling points in the period between 2008 and 2012. One sampling point was located a few kilometres from the Flix area and the other two were located before and after the DWTP, respectively. From the results obtained, it could be observed that no significant differences were obtained between the samples taken before and after the beginning of the decontamination process began, so it is important to highlight that this project has not affected the quality of the water supplied by the DWTP.

Influence of source composition and particle energy on the determination of gross alpha activity

The influence of different source compositions and α-particle energies on the detection efficiency of a gas-flow proportional counter was examined using experimental measurements and Monte Carlo simulations. Efficiency variation with alpha-particle energy was very marked, being less significant with the substrate composition. These results show that the determination of gross alpha activity in an unknown sample must be carried out very carefully in order to give a correct estimation of its activity.

Determination of actinides in samples obtained during dismantling activities

At present, some of the nuclear and radioactive facilities from CIEMAT employed in the past to perform activities related to the production of nuclear energy have been decommissioned as part of a more global on-going dismantling project. During the radiological characterization of a former laboratory a significant contamination of actinide elements in the old liquid effluents system was found. Samples obtained from two different locations (pipes and deposit) were measured by gamma- and alpha-spectrometry to quantify the contamination of the system. A quick and simple method using Actinide resin coupled with liquid scintillation counting (LSC) was employed for the determination of gross-alpha activity. The samples were also analyzed using a sequential leaching procedure to obtain information about the actinide association to certain geochemical phases with different solubilities such as carbonates, oxides, organic matter, etc., and thus, to choose the most appropriate clean-up method. Finally, the results obtained by the different techniques mentioned are compared and discussed.

Rapid determination of gross alpha-activity in sea water by coprecipitation

The radiological examination of water requires a rapid screening that permits the determination of gross alpha-activity in order to decide if further radiological analyses are necessary. The usual method of gross alpha-determination includes sample evaporation to dryness on a disk and counting using a ZnS(Ag) scintillation detector or a proportional counter. The determination of gross alpha-activity in sea water using this method has a number of drawbacks such as high mass attenuation, lack of homogeneity in the precipitate, and very small volume of sample. In this work, coprecipitation is proposed to enable a 500 ml sample of water to be analyzed. The minimum detectable activity (MDA) achieved was 0.004 Bq.l–1 for a counting time of only 4 hours. Weight variation, self-absorption factor, efficiency and blanks were studied. In order to test reproducibility of the method, several Spanish coastal sea water samples were analyzed by two different laboratories.

Simple Screening Method for Gross Alpha Activities of Pu and Am by Extraction Chromatography.

The simple and effective method for determination of gross alpha activities of Pu and Am in environmental and concrete samples was developed. Pu and Am in the sample solution were simultaneously separated from interference elements with extraction chromatography using an Eichrom TRU. SpecTM resin column. After separation, gross alpha activities of these elements on NdF3 micro precipitation were simultaneously measured by ZnS (Ag) scintillation counter. The chemical recoveries of these elements were quantitative. The interference of natural alpha emitter could not be found from the results. The advantage of the present method is quantitative recoveries of these elements and effective purification from natural alpha emitters (Th and U) . Furthermore, the present method reduces the time and cost for sample separation.

A method for the selection of the optimum counting conditions in a ZnS(Ag) scintillation detector

The well-known criteria for the selection of the optimum counting conditions in a ZnS(Ag) scintillation detector seem to restrict its applicability. These do not consider simultaneously operating voltage and electronic threshold variation to reach the best counting conditions. Therefore, a more general method for the determination of the optimum counting conditions in ZnS(Ag) scintillation detectors is proposed. In this method, a relationship between voltage and electronic threshold is derived for counting efficiency. In order to test the method, quality control procedures have been carried out as well as the determination of gross alpha activity in environmental samples.

Radiochemical determination of gross alpha activity in urine by adsorption on dextran gel Sephadex.

Abstract This work demonstrates that the phenomenon of surface adsorption of some fission products and alpha elements on “Sephadex” could be used to advantage as part of routine analytical procedure for the determination of gross alpha and beta activities in urine. The method consists of co-precipitation of the radionuclides on calcium phosphate from urine. adsorption of ions from the phosphate solution at pH 5·0 on Sephadex, then elution of the adsobed activity with 30 ml 0·5 N HCl, and finally preparing a source for α abd β counting. The recoveries of this method were about 85± 3·7 per cent.

The determination of gross alpha activity in urine by adsorption on glass fibre filter paper.

A description is given of work carried out to determine the optimum conditions for maximum surface adsorption of a number of alpha emitting radioelements on glass fibre filter paper. The effect of valency, pH and presence of pyrophosphate is discussed and a new technique for the determination of gross alpha activity in urine is given based on surface adsorption. Overall recoveries of thorium, protactinium, neptunium, plutonium, americium and curium are about 80 % using this procedure. The advantages of surface adsorption over conventional ion exchange are discussed and the development of other procedures based on this principle is suggested.