RU2422927C1 - Method to clean air from radioactive substances - Google Patents

Abstract

FIELD: ecology. ^ SUBSTANCE: method of highly efficient cleaning of air (gases) from radioactive substances, more specifically from tritium, iodine, cesium, strontium, beta particles of their compounds and finely dispersed dust-like inclusions is characterised by the fact that their sorption is carried out on a surface of a polymer coating, for instance, from a polyurethane poraxt-M2. Inside the polymer coating there are electrodes of stainless (highly alloyed) steel, height of polymer-coated electrodes (1-3 m) and distance between them (2-6 m) provide for supply of DC current with voltage of 25-50 kilovolt, resistance to atmospheric exposure, and ability to operate in stationary, field conditions or on a mobile movable structure. ^ EFFECT: achievement of high extent of cleaning from radioactive contamination of air regardless of atmospheric actions under conditions of low power inputs and possibility to create a stationary or a mobile structure, which allows for deactivation and subsequent multiple usage. ^ 1 dwg, 8 ex

Description

The invention relates to the field of environmental protection and the elimination of the consequences of accidents, relates to a process for the highly efficient purification of air (gases) from radioactive substances and can be used, in particular, in gas cleaning systems of enterprises producing radioactive materials, as well as in places of constant air pollution by radioactive substances .

It is known to use an adsorption filter material for cleaning air from the radioactive isotope of iodine and aerosols, consisting of a mixture of crushed fibrous material and granular carrier material impregnated with a metal salt (for example, silver nitrate). The mixing of fibers with granules and their impregnation is carried out simultaneously in a solution of a metal salt [Hladik O., Schwarzbach R. Adsorption filter material. A.S. USSR No. 952289].

A known method of purifying air from radioactive aerosols, carbon monoxide, radioactive iodine, hydrochloric acid vapors, tritium in enclosed spaces after accidents, is a mobile unit containing a vehicle, a control device, pumping and pumping gas ducts, sorption units for cleaning gases or air from toxic substances and aerosol particles, interconnected by pipelines with the ability to switch through bypass. The filtering elements of the gas cleaning units consist of VIOM-ANZ fabric, nickel-based electrolytic powders, sorbents Thermoxide 58 and zeolite, which increase the efficiency of cleaning the gas stream from hydrochloric acid vapor, a fine fraction of radioactive aerosols, radioactive iodine and water vapor [L.F. Belovodsky et al. A mobile unit for air purification in enclosed spaces after accidents. RF patent No. 2232439, Bull. 19. - S.568].

Closest to the claimed solution is a method of highly efficient purification of gases from radioactive molecular inclusions and aerosols of any composition using an absorbent filter material. The absorbent filter material is a system of structural elements randomly distributed in space and rigidly bonded to each other at points of contact. To obtain material, for example, boric acid and an emulsion of a binder solution are applied to the surface of structural elements, the structural elements are sintered at 1300 ° С, then they are impregnated and dried at room temperature for 1-2 days, then at a temperature of 150-200 ° С 1- 2 hours. For gas purification, a gas stream and the aforementioned volumetric highly porous structure with an activated surface are brought into interaction, and selective chemisorption of radioactive molecular inclusions and deposition of aerosols of any composition are carried out [A.V.Duka et al dsorbiruyuschy filter material, process for its preparation and a method for gas purification from radioactive substances. RF patent No. 2036698, Bull.16. - S. 98].

The disadvantages of the existing method are the use of evacuation of the filter material, high temperature sintering, several processes of thermal drying of the adsorption filter material and the use of salts of precious metal - silver. In addition, the filter material cannot be regenerated and ensures the absorption of radioactive iodine and iodide only under the condition of forced air convection. The method is ineffective for cleaning open air space and air velocity of more than 3 m / s. The method is not effective for air purification from such highly radioactive contaminants as cesium, strontium, tritium, etc.

The task of the invention is to achieve highly effective air (gas) purification from various radioactive substances.

The essence of the proposed invention in the present invention is a method of highly efficient purification of air (gases) from radioactive substances, and more specifically from tritium, iodine, cesium, strontium, beta particles of their compounds and finely divided dust-like inclusions, consists in their sorption on the surface of the coating made of polyurethane porast-M2, inside of which are stainless steel (high alloy) electrodes. The height of the polymer-coated electrodes (1-3 m) and the distance between them (2-6 m) provides for the supply of direct current voltage of 25-50 kilovolts, resistance to weathering, and the ability to work in stationary, field conditions or on a mobile mobile structure. Maintenance consists in de-energizing the system and deactivating the surface of the electrodes by known methods.

The technical result when using the present invention is to achieve a high degree of purification from radioactive contamination of air (gases) regardless of atmospheric influences in conditions of low energy consumption and the possibility of creating a stationary or mobile structure that allows decontamination and subsequent reuse.

The technical result is achieved due to the fact that when implementing the method under the influence of a high-voltage electric field of direct current, electrically charged radioactive elements and particles are sorbed and held by the surface of the polymer material of the electrode of opposite polarity. Sorbed radioactive elements as the surface becomes saturated (automatic control can be set using a dosimeter or a sensor such as a Geiger counter), after removing the high-voltage electric field, wash off with a decontamination solution, and then continue to operate the structure.

The advantages of the proposed method are as follows: the degree of purification from radioactive elements is possible actually to the background values of air (gases) in a continuous mode, regardless of humidity, wind speed (flows) and temperature with low power consumption. The installation does not resist air (gas) flow. In the areas of radioactive contamination of a large area, several facilities can be located taking into account the wind rose of the area in order to increase work efficiency.

Using the proposed combination of essential features set forth in the claims, it is possible to achieve the desired technical result - to perform highly effective cleaning of air (gases) from radioactive substances and fine dust-like inclusions due to their sorption on the surface of the polymeric coating of polyurethane, inside of which are stainless (highly alloyed) electrodes ) steel under the influence of DC voltage 25-50 kilovolts (see drawing). Examples of specific performance.

Example 1. In a cylindrical (or other) shape plate of positive (negative) polarity from a polymeric material, a polyurethane is made to install an electrode of stainless (high alloy) steel, 0.03 m in diameter, 1 m long. Both plates with electrodes are installed vertically at a distance of 2 m on an insulating material or ceramic support coated with rubber, fluoroplastic, etc. Then, from a high-voltage source (capable of operating under conditions of increased radiation if necessary), a constant potential is applied to the electrodes of 25 kilovolts with voltage stability not worse than 5%. An air stream labeled with radioactive molecules of tritium, iodine, as well as a source of beta particles from a target of nickel, cesium, and potassium is passed in the experimental room. The content of radioactive particles is 2-3 mg / m ³ . It is noted that the capture of radioactive particles from the air stream is more than 98% (the upper limit of measurements is limited by the existence of a radioactive background). After turning off the voltage to prevent the desorption of radioactive particles, the surface of the electrodes is deactivated; solutions are disposed of in the prescribed manner.

Example 2. Analogously to example 1, except that the length of the coated electrodes was 2 m, the distance between them was 3 m. It was noted that the capture of radioactive particles from the air stream was more than 97.5% (the upper limit of measurements is limited by the existence of a radioactive background).

Example 3. Analogously to example 1, except that the length of the coated electrodes was 3 m, the distance between them was 6 m. It was noted that the capture of radioactive particles from the air stream was more than 97.5%.

Example 4. Analogously to example 1, except that the length of the coated electrodes was 3 m, the distance between them was 8 m, a constant potential of 50 kV was applied. It is noted that the capture of radioactive particles from the air stream is more than 96%.

Example 5. Analogously to example 1, except that the length of the coated electrodes was 1 m, the distance between them was 5 m. It was noted that the capture of radioactive particles from the air stream was more than 90%.

Example 6. Analogously to example 1, except that the length of the coated electrodes was 3 m, the distance between them was 6 m, and methane labeled with radioactive elements was passed into the space between the electrodes. It is noted that the capture of radioactive particles from a methane stream is more than 97%.

Example 7. Analogously to example 1, except that the length of the coated electrodes was 3 m, the distance between them was 6 m, and carbon dioxide labeled with radioactive elements was passed into the space between the electrodes. It is noted that the capture of radioactive particles from the carbon dioxide stream is more than 97%.

Example 8. The method was carried out according to the prototype method. It is noted that the capture of radioactive particles (tritium, beta particles) from the flow of air (gas) does not occur.

Analysis of the results showed that the inventive method allows for a high degree of purification (97% or more) of air or gases from radioactive substances - tritium, iodine, cesium, strontium, beta particles of their compounds and fine dust-like inclusions due to their sorption on the surface of a cylindrical (or another) form of polymer coating of positive (negative) polarity, 1-3 m in size, located at a distance of 2-6 m, inside of which there are stainless (high alloy) steel electrodes under constant voltage current 25-50 kilovolts.

Information sources

1. A.S. USSR No. 952289 class B01D 39/00. Adsorption filter material. Authors: Hladik O., Schwarzbach R. Patentee: Academy der Wissenschafgen of the German Democratic Republic - 1982. - Bull. No. 31. - S. 32.

2. RF patent No. 2232439. Mobile unit for air purification in enclosed spaces after accidents. Authors: Belovodsky L.F .; Gazizov B.G .; Gorbunov N.E .; Goncharov V.N .; Dudin A.V .; Karpenko S.I .; Poklonsky A.A., Sladkov Yu.I.; Nikulin V.I., Khovrin A.N., Yukhnevich V.A .; Patent holder: Russian Federal Nuclear Center - All-Russian Research Institute of Experimental Physics. Application No. 2002116741/06, declared 2002.06.21, publ. 2004.07.10. - Bull. No. 19. - S. 568.

3. RF patent No. 2036698 (13) C1, G21F 9/02, 6 B01D 53/02. Adsorbent filter material, method for its preparation and method for purification of gases from radioactive substances. Authors: Duka A.V .; Grigoriev A.YU .; Vilensky MG, Patentee: Closed Joint-Stock Company - Mateks Research and Production Complex, Application No. 93049173/26, application. 1993.10.21, Publ. 1995.06.09. - Bull. No. 16. - S. 98.

Claims (1)

A method of highly efficient purification of air (gases) from radioactive substances, and more specifically from tritium, iodine, cesium, strontium, beta particles, their compounds and fine dust-like inclusions, characterized in that on the surface of the polymer coating, for example, from polyurethane porakst-M2 they are sorbed, characterized in that the electrodes made of stainless (highly alloyed) steel are located inside the polymer coating, the height of the polymer-coated electrodes (1-3 m) and the distance between them (2-6 m) provide for the supply of a constant voltage of 25-50 kV, resistance to weathering and the ability to operate in stationary field or the mobile mobile structure.