621.039Almost all artificial and many natural radionuclides accumulate in bottom deposits. These deposits play an important role in cleaning water ecosystems [1]. An equilibrium is established between the content of radionuclides in the water and in the bottom deposits. In this equilibrium the content of some natural radionuclides is 1-10 thousand times higher than in water [2], and the 137Cs content is distributed in the fresh water reservoir in a manner so that its activity is 4% of the total activity in the biomass (0. 1% by mass), 6% in water (85 % by mass), and 90% in soil (15 % by mass) [1]. Artificial radionuclides, including cesium isotopes, entering the reservoir are incorporated into biological processes and are deposited comparatively quickly on the bottom [3].The radionuclide content in the Tsimlyansk reservoir is of special interest because of the need to assess the degree of contamination of this large and important water resource in southern Russia by radionuclides as a result of the Chernobyl accident. In addition, together with radionuclides, it is possible to determine the content of natural radionuclides in the bottom deposits, since this can give information about the geochemical processes and sediment accumulation in the reservoir [1][2][3][4].Experimental Part. In 1990 75 bottom samples and 45 soil samples within the reservoir were obtained by standard methods for exploration of the Tsimlyansk reservoir. The methods used for obtaining the samples and for performing radionuclide analysis are similar to those employed in [5][6][7]. Gamma ray spectrometric measurements were performed on a tested radiometric apparatus based on a DGDK-80 Ge(Li) detector in the Marinelli geometry with one liter vessels and Dent's geometry with 0.1 liter vessels.Discussion. All bottom samples can be separated into three groups according to the 4~ content: first group -< 100 Bq/kg (-I0 samples); second group -100-450 Bq/kg (-45 %); and, third group -450-800 Bq/kg (-45 %). The first group of samples contains predominantly biological material and limestone; the second group contains sands; and, the third group contains clays. Data on the ratio of the 4~ content to the content of 226Ra and 228Ac also support this classification. For the first group these ratios are small: A(K)/A(Ra) -2.7 and A(K)/A(Ac); for the second group the ratios are 15-16; and, the ratios are highest for the third group: 12-16.5 and 18-19.5, respectively. The 226Ra and 228Ac content increases from the first to the third group. Samples of the second and third groups were obtained in the shore regions. The material of these samples is associated primarily with sediments.The 234mpa content and the content of 234Th in equilibrium with it were determined in 25 % of the samples. In these samples the ratio 226Ra: 2t4pb: 214Bi = 1:1:1, irrespective of the 234mpa content (in the range 10-1700 Bq/kg), i.e., within the limits of the errors of measurement radioactive equilibrium is observed between them. This shows that there is no 222Rn disbalance at the wa...
Most city residents live and work under conditions where the concentration of radon and its decay products does not exceed 20-200 Bq/m 3, while the world average is 5-150 Bq/m 3, including in Russia where the concentration is 4.8-160 Bq/m 3 [1, 2]. A small fraction of the population (-0.1%) encounters radiation hazardous conditions (concentration of radon and its decay products equal to 200-300 Bq/m 3 and higher), since the operating stapdards limit the emanation content to 100 Bq/m 3 for new buildings and 200 Bq/m 3 for old buildings [3].The main sources of radon inside buildings are soil and building materials with a high uranium or radium concentration, boilers, central thermal and electric power plants and thermal and electric plants burning coal and especially natural gas. The atmosphere in industrially developed cities can be contaminated with radon up to a level of 1.5 kBq/m 3 [4]. In the latter cases, the following radionuclides (in 101~ Bq) enter the atmosphere together with the products of incomplete fuel combustion: up to 6.8 238U, 4.2 232Th, 9.1 4~ and up to 1.1.1014 Bq 222Rn, including up to 1-104 and 0.1-3-1014 Bq/yr as a result of the combustion of gas and coal, respectively [1].Our objective in the present work was to develop the technical and methodological means for obtaining samples and for bulk determination of radionuclide composition of atmospheric air and air inside buildings, including radon and its decay products, with the aid of semiconductor "r-spectrometry under conditions of low-background measurements as well as radon in air in rooms with the aid of very simple radiometric means available to any ordinary radiation-monitoring laboratory.Determination of Radionuclides in Atmospheric Air. Atmospheric air was investigated in the southeastern part of Rostov-on-the-Don. To obtain aerosol samples, using a typical ventilation unit with a capacity of 54 m3/h, a stationary filteringventilation system was assembled. The system was placed in open air so that its intake opening was located 1.5 m above the ground. Dust was removed from the intake airflow by means of cotton fabric and impinged on a board with aerosol filters of the type AFA-RMA-20 with a total area of 740 cm 2. The velocity of the airflow at the exit was determined with a ASO-3 anemometer.Aerosol samples were obtained to determine the short-lived radon decay products within a time of 1-3 h and long-lived radionuclides (decay products of thoron and other nuclides) within a time of 10-24 h. The "y-ray spectrum of the filters was measured on a ROUS-II-15 setup after sampling was completed; the setup was certified by the Scientific and Industrial Association "All-Russia Scientific--Research Institute of Ph3/sicotechnical and Radioelectronic Measurements" of the State Standards Office of the Russian Federation as a second class sample system. The setup was assembled on the basis of a typical DGDK-80 Ge(Li) detector and a low-background chamber with multitayer shielding, which decreased the instrumental background by a factor of 80-100 [...
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