Removal of volatile 137Cs and 131I compounds from an air flow

The removal of volatile ¹³⁷Cs and ¹³¹I compounds from an air flow on various filtering elements was studied. ¹³¹I₂ and ¹³⁷CsOH are sorbed on basalt wool, but the degree of their recovery is low: ～86 and 90–93%, respectively, at the basalt wool bed height of 15–18 cm. The use of a cascade of bubblers in combination with a column packed with basalt wool allows virtually complete (>99.9%) removal of ¹³¹I and ¹³⁷Cs in the form of ¹³¹I₂, ¹³⁷Cs¹³¹I, and ¹³⁷CsOH from an air flow.     

Treatment of Gaseous Medium to Remove Radioactive Aerosols CsOH and Cs2MoO4 Labeled with Cesium-137

Radiochemistry - The process of the gas phase treatment to remove CsOH and Cs2MoO4 radioactive aerosols labeled with cesium-137 (hereinafter, 137CsOH and 137Cs2MoO4) was studied using a setup...     

Effect of UV radiation on the behavior of CsI radioaerosols in the gas phase

¹³⁷Cs¹³¹I radioactive aerosols formed upon evaporating CsI from a Pt support to an Ar atmosphere or air under UV irradiation or without it are studied. Without UV radiation, the degree of localization of the aerosols in a bubbler filled with aqueous Na₂S₂O₃ varies from 30% in argon to 60% in air. In sublimation of ¹³⁷Cs¹³¹I from the Pt heater, a considerable amount of nanoparticles is formed, which are not absorbed by the aqueous solution in the bubbler and are even capable of penetrating through a combined filter fabricated from a Petryanov filter and a “White Ribbon” paper filter. In the Ar atmosphere, the conversion of CsI is minimal, being initiated by traces of oxygen and moisture, as demonstrated by data on the Cs/I ratio in various fractions. In both Ar and air, UV radiation increases the localization of the radionuclides in the bubblers, simultaneously decreasing practically by half the amount of ¹³⁷Cs penetrating across the combined filter. Evidently, this is due to the fact that photoactivation promotes coarsening of nanoparticles through self-agglomeration or interaction with some coarser aggregates. A conclusion is made that UV radiation affects essentially the kinetics of aggregation of the aerosols in the gas phase, but not the rate of the chemical reactions occurring in the gas phase with participation of the aerosols.     

Localization of CsI Radioaerosols from the gas phase using various filtration elements

The behavior of ¹³⁷Cs¹³¹I radioaerosols, yielded by CsI evaporation from a Pt healer into argon or air, during their localization with aqueous solutions and various filtration materials [filters based on Petryanov fabric (from here on, Petryanov filter), “while band” paper filter, and TRUMEM metallic membrane filter] was studied. The degree of localization of ¹³⁷Cs¹³¹I radioaerosols was examined in relation to the amount of sublimed ¹³⁷Cs¹³¹I, the number of bubblers in the system, the size of the nozzle in the bubbling system, and the gas stream flow rate. The efficiency of localization of ¹³⁷Cs¹³¹I radioaerosols with a 10-layer stack of Petryanov filters from the gas stream with and without bubbling system was estimated. It was found that, at the stream velocity of 2–3 cm s^?1, a 10-layer stack of Petryanov filters with the total thickness of 3 cm takes up ca. 97% of total ¹³⁷Cs¹³¹I sublimed from the Pt heater. It was shown that the bubbling system does not affect the efficiency of localization of ¹³⁷Cs¹³¹I radioaerosols by Petryanov filters but only favors decrease of the aerosol load on these filters. Electron-microscopic examination of the particle-size distribution of the CsI aerosols penetrating through aqueous solutions was carried out, and various filtration materials (Petryanov filter and “white band” paper filter) were tested.     

Preservation of the charge of radioaerosols formed by condensation of supersaturated 137Cs131I vapor in the course of their bubbling through aqueous solution

Variation of the charge of radioaerosols formed by condensation of supersaturated ¹³⁷Cs¹³¹I vapor, observed when the gas flow passes through an aqueous solution, was studied. The supersaturated ¹³⁷Cs¹³¹I vapor was formed by evaporation of salt crystals from the metal surface heated to high temperatures owing to ohmic resistance. The radioactive aerosols preserve their charge even after bubbling through aqueous solutions, which allows using electric filters for localizing the aerosols.     

Condensation charging of aerosol particles in the course of their formation in the gas phase

The behavior of aerosols formed over boiling melts of substances (boiling temperature 500–1800 K) in a stream of a carrier gas at 300 K was studied. Microparticles of size from 0.2 to 10 μm, partially aggregated, were detected in the aerosol. In an applied electric field with an intensity of 150–1000 V cm⁻¹, the particles migrated toward the negatively charged electrode at a velocity of 5–15 cm s⁻¹. The velocity of their motion was a linear function of the field intensity and depended on the melt boiling temperature in accordance with the Arrhenius equation. Experimental data were interpreted on the basis of a concept that, in the course of the growth of each microparticle, vapor molecules adsorbed by it decompose into ions with nonequivalent transfer of cations and anions into the particle volume, i.e., the microparticles undergo growth charging at the activation energy of the cation release from the particle surface into vapor of approximately 0.5 eV.     

Centimeter and millimeter-wave radio signals attenuation inexplosions

The mechanisms of centimetre and millimetre radio wave attenuation in the explosion area of chemical explosives are analyzed. It is shown that the dominant factor is the attenuation caused by absorption in finely dispersed solid explosion products. The results of experimental measurement of the attenuation factor, the area dimensions important for attenuation and the duration of its existence for wavelengths of 0.4, 0.8, 3 cm are presented. A comparison of experimental data with results of derivations is performed