RU2646949C2 - Method and device for evaluating efficiency of protective action of filter elements and/or devices - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: group of inventions relates to means of radiochemical neutron-activation analysis (NAA) of air-cleaning processes (air mixture) from various kinds of toxic impurities by filtering and filtering-absorbing elements of respiratory organs protection means and other air cleaning devices. The method for evaluating the degree of protective action efficiency of filtering elements or devices comprises stages for activating a sample of toxic material by a flow of thermal neutrons, the activated sample of toxic substance is mixed with atmospheric air, the prepared air mixture is supplied under pressure for filtration, the prepared air mixture is filtered through filtering elements or devices. The pulses of activation of gamma-radiation detectors of air mixture before, during and after filtration are registered, the filtered mixture is discharged into the environment, and protective action efficiency of the filter elements or devices is estimated from the ratio of the activation intensities of the gamma-radiation detectors in the prepared and filtered mixtures.

EFFECT: possibility for testing and obtaining qualitative and quantitative information on the degree of protective action efficiency of the filter elements, and means for protecting respiratory organs and other air cleaning devices.

17 cl, 3 dwg

Description

The claimed group of inventions relates to means of radiochemical neutron activation analysis (NAA) of air purification processes (air mixture) of various kinds of toxic impurities by filtering and filtering-absorbing elements of respiratory protection and other air purification devices.

Neutron activation analysis is a highly sensitive method for determining the ultramicroquantities of unstable isotopes in various materials. The analytical signal in the NAA is the gamma radiation of radioactive nuclei formed during the preliminary irradiation of the test sample with thermal neutrons.

Various methods are known from the prior art for checking (testing) filtering and filtering-absorbing elements, as well as devices containing such elements (GOST 12.4.158-90 SSBT. Filtering personal respiratory protection. Methods for determining the time of protective action of filtering and absorbing boxes by harmful substances; GOST 12.4.160-90 SSBT. Filtering personal respiratory protection. Method for determining the time of protective action of filtering and absorbing boxes on carbon monoxide).

On the other hand, there are various options for using NAA to solve certain problems using the detection of gamma radiation from unstable isotopes in the test sample.

So, there is a known method for determining the leakage zone of a gas-filled product (AS USSR No. 1525522), according to which the shell of the test product is filled with control gas, the volume with the filled shell is irradiated with neutrons, and the sensors monitor the presence of neutrons in the volume of the control gas, register induced activity in the form of electrical impulses, the repetition rate of which is directly proportional to the concentration of the control gas.

Also known is a device for determining the content of elements in the surface layer of a sample (RF patent for invention No. 2411507), including a neutron source, a vacuum measuring chamber with an input neutron guide and an irradiated sample located in it, a gamma radiation detector located outside the measuring chamber, while the source neutron is a source of ultracold neutrons (UCN), the measuring chamber is connected to the intermediate chamber and is equipped with an output neutron guide connected to the UCN detector , a rotary shutter is installed in the input neutron guide, the passage section of the intermediate chamber is blocked by the output vacuum gate mounted on the rod with the possibility of movement, and the irradiated sample is mounted on the rod with the possibility of movement from the intermediate chamber to the measuring one.

A device for neutron activation analysis of long products is also known from A. with. USSR No. 1031302. The known device includes an irradiation source, an irradiation chamber and a measurement chamber, as well as a transport system for moving the test article, control and information processing units, all units being mounted as a whole to reduce the time between irradiation and measurement, thereby leading to reduce leaks.

The above means and methods are aimed at the application of neutron activation analysis for fixing or measuring leaks of any medium, checking the tightness of shells or determining the content of certain elements in samples.

No technical solutions have been identified from the prior art, consisting in the use of NAA methods and tools in testing filtering and filtering-absorbing elements of respiratory protective equipment and other air purification devices when determining the degree of effectiveness of their protective effect.

The objective of the present invention is to provide a method and device that enables through the use of NAA to study the effectiveness of filtering and filtering-absorbing (hereinafter: filtering) elements of respiratory protective equipment and other air purification devices, namely, to conduct a qualitative and / or quantitative assessment of the protective effect filter elements from a wide range of toxic impurities in the air.

The technical result achieved by using the claimed invention is to provide the possibility of testing and obtaining qualitative and / or quantitative information about the degree of effectiveness of the protective action of the filter elements, as well as respiratory protection and other air purification devices.

In other words, as a result of the application of the claimed group of inventions, it becomes possible to test filter elements that do not require qualified use of special equipment for the chemical analysis of the filtered air mixture, or chemical sensors and indicators, or biological objects. The proposed method can also be applied in cases where toxic substances or the composition of the toxic mixture are not identified.

The problem is solved in that in order to implement a method for assessing the degree of effectiveness of the protective effect of filtering elements or devices, according to the technical solution, a toxic sample of a toxic substance is activated by a thermal neutron flux, an activated toxic sample of a substance is mixed with atmospheric air, a prepared air mixture is fed under pressure for filtration, filtered the prepared air mixture through filter elements or devices, while registering the operation pulses of gamma-ray detectors of the air mixture before, during and after filtration, the filtered mixture is discharged into the environment and the effectiveness of the protective effect of the filtering elements or devices is evaluated by the ratio of the response intensities of the gamma radiation detectors in the prepared and filtered mixtures. In this case, a toxic substance that is initially in a solid, liquid, gaseous or suspended (aerosol, smoke) state can be used. So, in the case of the use of a solid toxic substance, after its preliminary neutron activation by a thermal neutron flux and before mixing the activated sample with atmospheric air, the toxic substance is sublimated by heating or transferred to the state of particles (smoke) suspended in air by burning. In the case of the use of a liquid toxic substance, after preliminary neutron activation by a thermal neutron flux and before mixing the activated sample with atmospheric air, the toxic substance is transferred into a gaseous state by evaporation of the liquid or into an aerosol state by using an aerosol generator. Also, the problem is solved in that the device for evaluating the effectiveness of the protective effect of the filtering elements or devices, according to the technical solution, includes a neutron activation unit for a toxic substance and a series-connected unit for preparing the air mixture with activated toxic substance, a filtering unit for the prepared air mixture, a unit for evaluating the effectiveness of the protective while the neutron activation block is an activation chamber with a connected source of thermal neutron flux in and with a container for accommodating the activated toxic substance, the air mixture preparation unit is a chamber with a connected air supply device and an activated toxic substance supply unit from the neutron activation unit, while the air mixture preparation unit is connected to the filtration unit via an air mixture supply pipe, which includes at least one independent compartment, configured to accommodate the cartridge with the studied filter elements or filter devices as well as a gamma radiation detector, wherein the prepared air mixture supply pipe is configured to supply the air mixture directly to each compartment of the filtration unit, and each compartment is equipped with a filtered air mixture removal pipe to the protective action effectiveness evaluation unit, which is a camera including at least one research section with at least one piping for supplying the filtered air mixture from the compartment of the filtration unit, and a tap and investigated filtered air mixture through a relief valve into the environment, with each section equipped with a gamma radiation detector. The device may further comprise a results processing unit, including a device for recording electrical pulses from gamma-ray detectors, connected to an analysis and processing unit for the pulses registered by it, while a multi-channel recorder can be used as an analysis and processing unit for pulses. The prepared air mixture supply pipeline can be equipped with a splitter that provides the possibility of supplying the air mixture directly to each compartment of the filtration unit, and is also equipped with at least one gamma radiation detector located in the splitter or directly in the pipeline. A gas cylinder is used as a container for accommodating an activated toxic substance in the case of using a gaseous toxic substance, while the activated toxic substance supply unit from the neutron activation unit is a valve connected to a high pressure gas cylinder with an activated gaseous toxic substance. Also, in the case of a liquid or solid toxic substance, a container is used as a container for its placement, wherein the activated toxic substance supply unit from the neutron activation unit is a branch connected to the liquid toxic toxic substance container equipped with an evaporator or aerosol generator, or , in the case of a solid toxic substance, the outlet is connected to a combustion chamber or sublimation of a solid activated toxic substance. A thermal neutron generator or a neutron conductor from a nuclear reactor is used as a source of thermal neutron flux. As gamma radiation detectors, flat semiconductor detectors are used. The cartridge with filter elements is a housing with at least one compartment, with layers of filtering or absorbing materials placed in each compartment. The cassette housing can additionally be equipped with an internal channel and at least one gamma radiation detector located in the internal channel, with the possibility of its movement between the compartments of the cartridge.

The claimed group of inventions is illustrated by the following drawings, while

in FIG. 1 schematically shows the inventive device with a division into blocks;

in FIG. 2 shows one embodiment of a filtering unit;

in FIG. 3 schematically shows a cartridge for accommodating filter elements.

The positions in the drawings indicate:

1 - neutron activation block;

2 - block preparation of the air mixture;

3 - filtration unit;

4 - block assessment of effectiveness;

5 - block processing results;

6 - activation camera;

7 - source of thermal neutrons;

8 - gas cylinder;

9 - container;

10 - air supply device;

11 - a combustion chamber;

12 - evaporator;

13 - air supply pipe;

14 - splitter;

15 - cartridge with investigated filter elements;

16 - gamma radiation detector;

17 - compartment;

18 - pipeline discharge;

19 - research section;

20 - block registration pulses (primary data);

21 - analysis unit;

22 - computer;

23 - filtering device;

24 - cassette case;

25 - an internal channel;

26 - office compartment.

The inventive device is a multi-chamber design, the individual functional units (chambers) of which are connected by pipelines. The device includes a neutron activation unit 1 of a toxic substance sample, an air mixture preparation unit 2, a filtration unit 3, and a protective action effectiveness evaluation unit 4. Moreover, a neutron activation unit of a toxic substance sample can be placed separately and is not physically connected with other blocks. This unit is a sealed activation chamber 6 (made of a metal sheet with a thickness of 1-2 mm), to which a source of thermal neutron flux is connected, which can be used as a reactor neutron conductor or a neutron radioisotope generator. The chamber is configured to place a gas cylinder 8 in it, in which a toxic gas (for example, chlorine, phosgene, carbon monoxide) is stored under pressure, or a container 9 in which a solid (for example, polyvinyl chloride, bisphenol) or liquid ( e.g. silyl acid, dichloroethane) is a toxic substance.

The neutron activation unit 1 is autonomous, independent of other units and can be placed, for example, in the laboratory of an operating nuclear power plant in order to minimize the movement of toxic substances.

The composition of the claimed device also includes an air mixture preparation unit 2, which is a chamber of 0.02-0.1 m ³ volume, to which atmospheric air supply 10 is organized, for example, through a compressor with a power of 200-500 W, as well as an activated toxic supply unit substances through the pipeline. This assembly is a pipeline to which a combustion or sublimation chamber 11 is connected, which is used in case of using a solid toxic substance, and / or an evaporator (or aerosol generator) 12, in case of using a liquid toxic substance, and / or a gas cylinder with a reducer and low pressure chamber, in the case of the use of a gaseous toxic substance. The chamber for the preparation of the air mixture provides the composition and condition of the air mixture, as close as possible to the conditions of a real polluted air environment. By changing the supply of atmospheric air and activated toxic substances, the degree of “pollution” of the air can be regulated. The chamber is equipped with a tap of the prepared air mixture, which is a pipe 13 connecting the chamber of the air mixture preparation unit and the filtration unit.

The filtration unit 3 is a chamber containing at least one filter compartment 17. There may be several compartments for testing several filter elements at the same time. At the same time, the pipeline supplying the prepared air mixture to the filtration unit can be equipped with a splitter 14, including the required number of bends (according to the number of compartments). So, a branch from the pipeline is brought into each compartment to ensure uniformity of supply of the prepared air mixture to each of the compartments. Cassettes with filter elements 15 or sets of test filters or prefabricated filter devices 23. and filtering and absorbing elements. Such gamma-ray detectors can also be placed in the air supply line (in the case of a filtration unit with one compartment) or in a splitter (in the case of a filtration unit with several compartments). The cartridge with filtering elements is a frame housing 24 containing at least one compartment in which layers of filtering or absorbing materials are placed. The use of a larger number of compartments makes it possible to place filter elements in different sequences, use different compositions, etc., which will allow you to choose the most optimal ordered set of filter and absorbing elements used for specific toxic impurities or pollutants. An internal channel 25 can be made in the cartridge case, in which, for the most information, an additional gamma-ray detector is placed, and it is possible to move it relative to the compartments of the case 26 to measure the level of radioactivity in the area of a particular layer of the filter element. The exit from the filtration chamber is made in the form of a discharge pipe for the filtered air mixture or several separate pipelines according to the number of filter compartments. Outlet pipelines (bends) 18 connect the filter unit chamber to the protective action effectiveness evaluation unit 4, which is a camera divided into research sections 19, the number of which corresponds to the number of compartments of the filter unit. At the same time, each pipeline leading from the filtration unit is connected to the corresponding research section. Gamma radiation detectors, for example, semiconductor flat detectors, are located in the sections, and bends equipped with relief valves are made to discharge the filtered air mixture coming from the filtration unit into the environment (into the outer space) through the air duct of the ventilation system. Thus, in the device, gamma radiation detectors are located directly in the zones of preparation and filtration of the air mixture, that is, in a polluted environment (before filtration at the inlet of the filtration unit and directly in the compartments of the filtration unit), as well as after the filtration unit (in the study sections) . The difference in the quantitative indicator of the intensity of the flows of recorded pulses before and after filtering judges the effectiveness of the protective action of the studied filter elements and devices. Electrical pulses from the detectors are recorded by the results processing unit, including the primary data registration unit 20 and the registered pulses analysis unit 21. The results processing unit may be, for example, a multi-channel recorder. Chart recorders allow you to register input data and output data on a paper chart tape in the form of a graph for a visual assessment of filtering efficiency. Also, various types of recorders — paper, video, or technological — can be used as a processing unit for the results, providing the ability to output analysis results in various forms, as well as the possibility of further conversion and use of an array of primary recorded electrical pulses from gamma radiation detectors. The unit for processing the measurement results also includes an input bus intended for connecting through the appropriate cable lines to the drive devices of the gearboxes, valves, dampers, and other devices, an input bus intended for connecting through the corresponding cable lines to the primary data recording devices connecting them to those located in the corresponding areas of pressure sensors, air flow rate, gamma radiation detectors. The primary data recording units are connected via output buses to a computer 22, which is designed to implement algorithms for processing the array of registered primary electrical impulses and control the entire device through an output bus connected via appropriate cable lines to devices of gear drives, valves, dampers, and other devices.

Thus, the device provides a qualitative and quantitative analysis of the effectiveness of the protective action of the filter elements. A qualitative analysis of the protective effect of a certain set of filtering and filtering-absorbing elements consists in the registration by the detectors of a set threshold level of gamma radiation during continuous / discrete filling of the study chamber with a certain amount of filtered air mixture. Quantitative analysis of the protective effect of a certain set of filtering and filtering-absorbing elements can be carried out on the basis of automated processing in accordance with a certain algorithm of the results of measurements of the volumes of the air mixture passed through the filtering element, as well as continuous detection of gamma radiation by detectors.

The inventive method is implemented using the inventive device as follows.

The use of neutron activation analysis in assessing the effectiveness of filter elements or ready-made filter devices will provide an opportunity to quickly and accurately assess the degree of effectiveness of the protective action of filter elements, as well as respiratory protection and other air purification devices, to choose the most effective ordered set of filters, as well as to test finished products before their operation.

To implement the proposed method, a mixture of air and a sample of a toxic substance is prepared in a neutron activation unit. A toxic substance can be used in any state of aggregation: solid, liquid or gaseous. A neutron flux from a neutron conductor of a reactor or other thermal neutron generator pre-activates a toxic substance sample placed in the activation chamber. A toxic substance is bombarded with thermal neutrons, as a result of which nuclei of atoms of the substance capture their radioactive isotopes with a short half-life. A particular advantage of this method is that the duration of the induced radiation is usually from a few seconds to several hours.

As a result of the bombardment, an activated toxic substance is obtained, enclosed in a gas cylinder if a gaseous fraction is used, or in a container if a liquid or solid toxic substance is activated.

Next, a sample of the activated toxic substance is mixed with the air stream in the air mixture preparation unit. By changing the air mixture supply, the required concentration is achieved (measured in maximum permissible concentrations of MPC - from safe (<1) to several tens or hundreds of MPC).

To mix a gaseous activated toxic substance with atmospheric air, a sample from a gas cylinder is mixed with pressurized atmospheric air in a special chamber for preparing the air mixture. At the same time, the readings of the pressure sensors are recorded, the concentration of the components of the air mixture is measured and adjusted.

To prepare the mixture in the case of using a liquid toxic substance, the activated toxic substance is preliminarily evaporated or a dispersed phase (aerosol) is obtained, and the vapors or aerosol of the activated toxic substance thus obtained are mixed in the same way with a stream of atmospheric air. To do this, use an evaporator or an aerosol generator connected to an activated toxic substance supply pipeline, in which the process of phase transition of a liquid toxic substance to a gaseous state or the formation of a dispersive, condensation or mechanical aerosol is carried out.

To prepare the mixture in the case of a solid toxic substance, the activated toxic substance is sublimated or burnt in a heat or smoke chamber, also connected to the activated toxic substance supply line, and the exhaust gases containing the activated toxic substance generated by sublimation or combustion are similarly mixed with atmospheric by air. Thus, as a result of this step, a mixture of atmospheric air with vapors or aerosol or smoke of an activated toxic substance is obtained. Further, the mixture thus prepared is fed to the filtration unit through the prepared air mixture supply pipeline and filtered by the filter elements under study, while electrical pulses from gamma radiation detectors are recorded before filtration and in its process, as a result of which an array of primary electric pulses is formed for subsequent evaluation of efficiency filtering. In the case of the study of several filter elements and the execution of the chamber of the filtration unit with several compartments, the prepared air mixture is fed into each compartment through a splitter connected to the inlet pipe. In the compartments of the filtration unit, pre-placed cartridges with the studied sets of filter elements or finished filter devices. Obviously, the flow of the prepared air mixture saturated with isotopes, passing through the filtering elements, falls into the range of gamma radiation detectors, which record the decay rate of radioactive isotopes. After passing through the filtration unit, the flow is sent to the protective action effectiveness evaluation unit, where the presence of radioactive isotopes is also detected by the operation of gamma-ray detectors located in each section of the effectiveness evaluation unit. Through the relief valves, the filtered stream is discharged into the environment through the ventilation system, and the effectiveness of the protective action of the studied filter elements is judged by the recorded intensities of the gamma radiation detectors in the filtration unit and after it. In this case, the initial readings of gamma-ray detectors are recorded in the processing unit, then they are processed and analyzed in accordance with a certain algorithm, after which the results are displayed in an easy-to-read form on an external storage medium (for example, a computer monitor).

Claims (17)

1. A method for evaluating the effectiveness of the protective action of filtering elements, means or devices, characterized in that they activate a toxic substance sample by a thermal neutron flux, mix the activated toxic substance sample with atmospheric air, prepare the prepared air mixture under pressure for filtration, filter the prepared air mixture through filter elements or devices, while registering the operation pulses of the gamma radiation detectors of the air mixture before, during and after filtering, you odyat mixture was filtered in the environment and relative intensities triggering gamma-radiation detectors prepared in filtered and mixtures evaluate the effectiveness of the protective action of the filter elements or devices. 2. The method according to p. 1, characterized in that as a toxic substance using a substance that is initially in a solid, liquid, gaseous or suspended (aerosol, smoke) state. 3. The method according to p. 2, characterized in that after its preliminary neutron activation by a thermal neutron flux and before mixing the activated sample with atmospheric air, the toxic substance is sublimated by heating or transferred to a state of suspended particles (smoke) in the air by burning. 4. The method according to p. 2, characterized in that they activate a sample of a liquid toxic substance, while after preliminary neutron activation by a thermal neutron flux and before mixing the activated sample with atmospheric air, the toxic substance is transferred into a gaseous state by evaporation of the liquid or into an aerosol state by using aerosol generator. 5. A device for evaluating the effectiveness of the protective effect of filtering elements or devices, characterized in that it includes a neutron activation unit for a toxic substance and a series-connected unit for preparing the air mixture with the activated toxic substance, a filtration unit for the prepared air mixture, a unit for evaluating the effectiveness of the protective effect, wherein neutron activation is an activation chamber with a connected source of thermal neutron flux and a capacity to accommodate the activated of a toxic substance, the air mixture preparation unit is a chamber with a connected air supply device and an activated toxic substance supply unit from the neutron activation unit, while the air mixture preparation unit is connected to the filtration unit via an air mixture supply pipe, which includes at least one independent compartment made with the possibility of placing the cartridge with the studied filter elements or filter device, as well as a gamma radiation detector, while the prepared air mixture supply pipeline is arranged to supply the air mixture directly to each compartment of the filtration unit and each compartment is equipped with a filtered air mixture discharge pipeline to the protective action effectiveness evaluation unit, which is a chamber comprising at least one research section with at least connected one pipeline for supplying the filtered air mixture from the compartment of the filtration unit, and the removal of the studied filtered air mixture through a relief valve into the environment, with each section equipped with a gamma radiation detector. 6. The device according to p. 5, characterized in that it further comprises a results processing unit, including a device for recording electrical pulses from gamma-ray detectors and an analysis unit, while the device for recording electric pulses is connected to an analysis and processing unit for pulses recorded by it, In this case, a multi-channel recorder can be used as a pulse analysis and processing unit. 7. The device according to p. 5, characterized in that the pipeline for supplying the air mixture is equipped with a splitter, providing the possibility of supplying the air mixture directly to each compartment of the filtration unit. 8. The device according to p. 7, characterized in that the pipeline for supplying the air mixture is additionally equipped with at least one gamma radiation detector, located in the splitter or directly in the pipeline. 9. The device according to claim 5, characterized in that as a container for accommodating the activated toxic substance, a gas cylinder is used in the case of using a gaseous toxic substance, 10. The device according to claim 9, characterized in that the site for supplying the activated toxic substance from the neutron activation unit is a valve connected to a high pressure gas cylinder with an activated gaseous toxic substance. 11. The device according to claim 5, characterized in that a container is used as a container for accommodating an activated toxic substance in the case of using liquid or solid toxic substances. 12. The device according to p. 11, characterized in that the site for supplying the activated toxic substance from the neutron activation block is a branch connected to a container with a liquid activated toxic substance equipped with an evaporator or aerosol generator. 13. The device according to p. 11, characterized in that the site for supplying the activated toxic substance from the neutron activation block is a branch connected to the combustion chamber or sublimation of the solid activated toxic substance. 14. The device according to claim 5, characterized in that a thermal neutron generator or a neutron conductor from a nuclear reactor is used as a source of thermal neutron flux. 15. The device according to p. 5, characterized in that as detectors of gamma radiation using flat semiconductor detectors. 16. The device according to claim 5, characterized in that the cartridge with filtering elements is a housing with at least one compartment, with layers of filtering or absorbing materials placed in each compartment. 17. The device according to p. 16, characterized in that the cassette body is further provided with an internal channel and at least one gamma radiation detector located in the internal channel, with the possibility of its movement between the compartments of the cartridge.

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