[en] Determination of uranium content in aerosol filters is a part of the regular monitoring program for nuclear facilities. The monitoring of the atmospheric uranium releases, resulted from the incineration of uranium bearing waste, is done by the analysis of representative samples collected from the evacuation ducts of the installation. The monitoring method is based on the determination of the uranium content of the filters by alpha-spectrometry. The process consists of the following steps aimed to create the source for alpha spectrometry measurement: (1) dissolving of aerosol filters with concentrated nitric acid and hydrogen peroxide, (2) addition of a known amount of U tracer, (3) separation of uranium from other actinides using UTEVA resin, (4) precipitation with cerium fluoride and filtration using a 0.1 micron 25 mm filter. The validation of the method is based on the reference materials approach, by considering the recoveries and the counting efficiencies. (authors)

[en] The procedure for determination of uranium content in aerosol filters by alpha spectrometry is an appropriate method of monitoring the releases in the environment. The procedure is based on the use of UTEVA resin to separate the uranium. For sample preparation, the filter is dissolved with concentrated nitric acid and hydrogen peroxide, at boiling temperature. Separation yield of actinides is monitored with addition of a known amount of "2"3"3U tracer, to the initial sample. Source preparation for alpha spectrometry is performed by micro-precipitation with cerium fluoride. The sample is filtered by using a 0,1 micron 25 mm filter, followed by the mount on stainless steel plate, for subsequent counting by alpha-spectrometry. The separation yields for the analytes were compared, as concerns the recoveries and the counting efficiencies, with used reference materials. (authors)

[en] The measurement of radioactivity concentrations in soil is an important tool for the monitoring of the environment. For this purpose, within our laboratory has been implemented a radiochemical procedure for the determination of alpha-emitting isotopes of uranium, plutonium and americium in soil samples. The main steps of the procedure include leaching and dissolution of the sample, separation by extraction chromatography, source preparation and alpha-spectrometry. The analysis of environmental samples for low levels of U, Pu, Am and other actinide elements is often hampered by sample-dependent problems involving the composition and/or mineralogy of specific samples. While relatively small samples (1-2 g of soil) are required to reach the extremely low detection limits occasionally mandated for environmental monitoring. "2"3"2U, "2"4"2Pu and "2"4"3Am were added to the sample for chemical yield monitoring and to correct the results and to improve precision. Actinides are separated and purified by extraction chromatography with UTEVA and TRU resin, co-precipitated with cerium fluoride, filtered, and counted by alpha-particle spectrometry. The separation yields for the analyses were determined following each separation step and the global separation yields were determined for the entire analytical process. Results show a chemical yield of 90% for uranium, 30% for plutonium and 70% for americium. Also, the activity values obtained for these samples were comparable with the reference material values. (authors)

[en] Recently, we showed that the alpha activity in liquid samples can be measured using a liquid scintillation analyzer without alpha/beta discrimination capability. The purpose of this work was to evaluate the performances of the method and to optimize the procedure of the sample preparation. A series of tests was performed to validate the procedure of alpha emitting radionuclides extraction in aqueous samples with Actinide Resin, especially regarding to the contact time required to extract all alpha nuclides. The main conclusions were that a minimum 18 hours stirring time is needed to achieve a percent recovery of the alpha nuclides grater than 90% and that the counting efficiency of alphas measurements with LSC is nearly 100%. (authors)