Time filter

Source Type

Obninsk, Russia

Drofa A.S.,RPA Typhoon
Izvestiya - Atmospheric and Ocean Physics | Year: 2010

The results of a numerical simulation of the action of hygroscopic particles on a warm convective cloud with the purpose of obtaining additional precipitation are presented. The one-dimensional numerical model considered in this work describes the evolution of the cloud medium in the central part of an axisymmetric convective cloud at the specified height-variable velocity of the upward air flow which forms the cloud. Our model comprehensively describes microphysical processes in the cloud medium with the use of the kinetic equation for the size distribution of cloud droplets. This model makes it possible to obtain the spatiotemporal pattern of the cloud formation and development and to analyze regular features in the cloud evolution under the action of hygroscopic reagents. The cloud characteristics calculated with the use of this model correspond to the cloud parameters observed in natural conditions of the atmosphere. The process of precipitation stimulation by hygroscopic particles in convective clouds with vertical thicknesses of 2.5-4.5 km was analyzed on the basis of the results of numerical calculations. The results of calculations of the dependence of the intensity and total amount of precipitation on the vertical cloud thickness and parameters of particles introduced into the cloud are presented. It is shown that hygroscopic particles with root-mean-cube radii of 1-1.5 μm are the most effective for acting on warm convective clouds with the purpose of obtaining additional precipitation. In this case, the required reagent expenditure is 100-200 kg/km2. The conditions necessary for obtaining the maximal positive effect of the action are elucidated. © 2010 Pleiades Publishing, Ltd. Source

Krylov A.L.,RAS Nuclear Safety Institute | Nossov A.V.,RAS Nuclear Safety Institute | Nikitin A.I.,RPA Typhoon | Kryshev A.I.,RPA Typhoon
Radioprotection | Year: 2011

Observations carried out in the frame of the ISTC project 3547 [1] were used to parametrize and validate the model of radionuclides transport from Siberian Chemical Combine (SCC) by the Tom and Ob rivers and also to assess discharges of radioactive substances from SCC to the Tom River and to estimate possible contamination of the rivers in case of accidents. © 2011 EDP Sciences. Source

Smirnov V.V.,RPA Typhoon
Izvestiya - Atmospheric and Ocean Physics | Year: 2010

We studied the influence of the characteristics of the atmospheric ionization and physical-chemical state of condensation nuclei on the electric state of convective cells. Based on the results of experiments in an adiabatic chamber with a volume of 3200 m 3, we found that, with increase in relative air humidity H from 40 to 95% with an equivalent ascent rate of 100-400 cm/s, excessive charges in amounts of about 10 3 or more elementary charges per cm 3 may be accumulated on the nuclei. The sign of the charge depends on the chemical composition of the hygroscopic nuclei. For instance, media with insoluble nuclei (porous silica, etc.) typically have prevailing negative charges; those with soluble nuclei (sodium chloride, etc.) are dominated by positive charges. At H = 60-90%, the electrization of soluble nuclei can be interpreted in the diffusion-kinetic models of the ion charging of aerosols. Considerable negative volume charges, which appear on insoluble hygroscopic nuclei during a rise in humidity from 40 to 70%, are explained by the structuring of surface water films, which exhibit a resemblance to negative lightweight ions. At high values (H > 90%), it is necessary to take into account the resemblance of the wetted surfaces to positive lightweight ions. We showed for the first time that, at ion formation rates of 3 and 10 10 ion pairs/(cm 3 s), the differences in the volume charge and wetting rate of condensation nuclei are insignificant. It is concluded that, in many meteorological situations, the first stage of electrization of the convection-derived cloud media is the ion charging of the condensation nuclei. © 2010 Pleiades Publishing, Ltd. Source

Gusarov A.,RPA Typhoon | Il'Icheva N.,RPA Typhoon | Konoplev A.,RPA Typhoon | Lee S.D.,U.S. Environmental Protection Agency | And 3 more authors.
Radioprotection | Year: 2011

Fine radioactive particulate dispersal in outdoor areas presents significant economic, social, environmental and public health concerns. The interactions of these radioactive particles with urban surfaces need to be well understood to develop optimized decontamination strategies. The major environmental factors influencing these interactions are relative air humidity, temperature and rain. The objective of this work is to investigate the fate and transport of water soluble cesium deposited on conventional urban building materials, especially concrete, brick, asphalt, limestone, and granite, under various environmental conditions (relative humidity (RH), and atmospheric precipitation). The data on the kinetics of 137Cs desorption from building materials by the solution containing 100 mM of Ca2+ and 0.5 mM of K+ have shown that the shape of the 137Cs desorption curves is similar for all building materials. There is a rapid initial decrease in the activity of the sorbed 137Cs. The desorption rate first decreases quickly during 7-10 days and practically does not change later. The remaining 137Cs in building materials that is not desorbed by the solution is 30-40% of the initially sorbed amount. For the building materials of interest, radiocaesium interception potentials (RIP). The RIP(K) value has been shown to range from 20 to 300 mM/kg and increase in the order: limestone > brick > concrete > granite > asphalt. The fine fraction of building materials (<0.125 mm) sorbs 137Cs better than the coarse fraction (0.0125-0.25 mm). Based on RIP(K) value and measured concentration of cations the distribution coefficients Kd(137Cs) were determined. The study of the mechanisms of radiocesium binding by different components of building materials, based on sequential extraction technique, shows that the highest ability to bind 137Cs is characteristic of asphalt which retains 40.9±1.0 % of 137Cs after all extractions. By the ability to bind 137Cs with the residual fraction, the studied materials form the following sequence: concrete > limestone > granite > brick. Method to study radionuclides distribution in depth of building materials using layer-by-layer grinding has been developed. © 2011 EDP Sciences. Source

Discover hidden collaborations