RU2362186C1 - Method for radio-environmental monitoring of industrialised region - Google Patents

Abstract

FIELD: ecology.

SUBSTANCE: invention relates to environmental protection, in particular to radio environmental monitoring of industrialised region during the evaluation of nuclear facilities in the region and the influence of specialised enterprises for radioactive pollution of the environment, evaluating the radiation exposure of the population. The method for radio-environmental monitoring of the industrialised zone includes sampling of the atmosphere aerosol particulates from 0.1 to10 microns on the air filtering system with a capacity from 1200 to 3500 m³/hour; sample preparation is carried out by weighting using the filter of the air filtering system with sample aerosol particulates from 0.1 to 10 microns following exposure to the filter; further analysis of the contents for natural and human generated radionuclides are carried out with a gamma spectrometer, along with automatic analysis, after which the samples are incinerated in a muffled oven at a temperature of 400°-500°C, the ash remains of each sample are determined and sent for evaluation of α and β activity in a low-background setting, and for semiconductor gamma-spectrometry for determining the content of the radio nuclides, the data received is entered into a database and according to the results of the measurements the concentration of dust, specific activity of the radionuclides, the effective human dosage and its content according to organic and mineral fractions are evaluated, the evaluation of the radio-ecological conditions of the industrialised area on the basis of the geo-informational system by construction of information cards of fields of radiation properties and identification of territorial zones of the industrialised region with increased levels of radionuclides and effective internal doses of radiation for humans.

EFFECT: determination of the concentration of dust in the atmosphere; determination of the radio activity in the air and the effective dose of internal radiation for humans.

Description

The invention relates to environmental protection, in particular to radioecological monitoring of an industrial region when assessing the radiation situation in the region and the impact of specialized enterprises on radioactive pollution of the environment, and the assessment of radiation doses to the population.

A known method for assessing the radiation situation and rehabilitation of territories contaminated with radionuclides, including sampling from environmental objects, sample processing, analysis for the content of radionuclides, the selection and purification of radionuclides, methods for their determination [1]. However, the method does not take into account the degree of accumulation of radioactive substances in natural environments, which does not allow to dynamically obtain the necessary information about the state of the environment and the territory of the industrial region.

The closest to the proposed method (prototype) is a method of radioecological monitoring of an industrial region, including sampling of atmospheric air, sample preparation, analysis of samples for the content of natural and technogenic radionuclides and automatic processing of analysis data, characterized in that they additionally carry out sampling of soils, industrial soil, surface, ground and groundwater, precipitation, dry fallout, snow cover, bottom sediments and vegetation, then carry out a sample preparing the samples by complete decomposition of the samples by high-frequency heating, the prepared samples are sent to a low-background setup to assess alpha and beta activity, when the alpha and / or beta activity in the sample is twice as high as the average specific activity, the sample is sent to additional analyzes for alpha and / or gamma spectrometers, while determining the quantitative and qualitative contents of radionuclides, as well as determining the content of tritium, carbon-14 and nickel-63 on a low-energy liquid by a tillation analyzer, record the measurement results in the direction of the prepared samples to assess α- and β-activity, determine the quantitative and qualitative content of radionuclides, write the measurement results in an analytical database located on a file server of the information-analytical system, in which as a basic set development tools for this system, the "MS office" package was selected, which includes MS Access as a component, and the radioecological situation is assessed based on the processing results and the region based on the geographic information system by constructing electronic maps of the fields of radiation characteristics and identifying areas with a high content of radionuclides, determining the state of the radiation situation in the industrial region [2].

The disadvantage of the prototype is that the radiation status of the territory of the industrial region is monitored, but the dose load on the population of the industrial region is not evaluated, in particular, the internal effective dose of human exposure, which cannot be determined without measuring the volumetric concentration of dust in atmospheric air, is not evaluated.

The technical result of the proposed method of radioecological monitoring of an industrial region is to determine the volume concentration of dust contained in atmospheric air, to determine the specific activity of radionuclides in atmospheric air and the effective dose of internal radiation to humans.

To achieve the specified technical result, a method for radioecological monitoring of an industrial region is proposed, including sampling of atmospheric air with a fraction of aerosol particles from 0.1 to 10 microns in an air-filtration plant with a capacity of 1200 to 3500 m ³ / h; sample preparation is carried out by weighing the filter of an air-filtering unit with selected aerosol particles with a fraction of 0.1 to 10 microns after exposing the filter; Further, samples are analyzed for the content of natural and technogenic radionuclides on a gamma-ray spectrometer, the analysis data are automatically processed, after which the samples are ashed in a muffle furnace at a temperature of 400-500 ° C, the ash content of each sample is determined and sent to evaluate α- and β-activity on a low-background setup and on a semiconductor gamma-spectrometer for determining the composition of radionuclides, the obtained data are entered into the analytical database and the volume concentration of whether the specific activity of radionuclides, the effective internal dose of a person and its composition by organic and mineral fractions, carry out the above assessment of the radioecological situation of an industrial region based on a geoinformation system by constructing maps of radiation characteristics fields and identifying areas of an industrial region with a high content of radionuclides and an effective internal dose human exposure.

Distinctive features of the proposed method of radioecological monitoring of an industrial region is that sampling of aerosol particles of atmospheric air with a fraction of 0.1 to 10 microns is carried out on an air filter plant with a capacity of 1200 to 3500 m ³ / h, and sample preparation is carried out by weighing the filter of an air filter plant with selected aerosol particles from 0.1 to 10 microns after exposure, and then carry out the above analysis of samples for the content of natural and man-made radionuclides and automatic processing the analysis data, after which the samples are ashed in a muffle furnace at a temperature of 400-500 ° С, the ash residue of each sample is determined and sent to a low-background setup for assessing α- and β-activity and to a semiconductor gamma-ray spectrometer for determining the composition of radionuclides , the obtained data are entered into the analytical database and the results of measurements determine the volume concentration of dust, the specific activity of radionuclides, the effective internal dose of a person and its composition by organic and mineral fraction , conduct the above assessment of the radioecological situation in the industrial region on the basis of the geographic information system by constructing maps of the fields of radiation characteristics and identifying areas of the industrial region with a high content of radionuclides and an effective internal dose to humans.

The selection of aerosols in the surface layer of the atmosphere is carried out using an air filtration unit (VFU) with a capacity of 1200 to 3500 m ³ / h. This power is an order of magnitude greater than the power of existing installations for registering aerosol particles in atmospheric air and allows you to accumulate a significant amount of aerosols and radionuclides on the filter, which contributes to the achievement of a technical result - reliable determination of the volume concentration of dust in atmospheric air and determination of the specific concentration of radionuclides.

VFUs are installed in the measuring pavilion, which has blinds on the walls, which allows cutting off aerosol particles of atmospheric air larger than 10 microns and registering aerosol particles with sizes less than 10 microns on the VFU filter. The used filters of the FPP-15-1.5 / FPA-15-1.5 type, in turn, effectively absorb aerosols larger than 0.1 microns. As a result, aerosols with a fraction of 0.1 to 10 microns are collected, which accumulate in the tracheobronchial and olveolar regions of the human respiratory tract, i.e. a biologically significant fraction of aerosols, which allows to achieve a technical result - the determination of the internal effective dose of a person.

Sample preparation by weighing the WFD filter after exposure allows you to determine the total mass of the selected aerosol particles with a fraction of 0.1 to 10 microns with an accuracy of 0.01 g due to the fact that a significant amount of aerosol particles accumulate on the filter and the technical result is achieved - it is determined with high accuracy total volume concentration of dust in atmospheric air.

Ashing of samples in a muffle furnace at a temperature of 400-500 ° C contributes to burnout of the organic dust fraction and the mineral fraction remains. The lower limit of the ashing temperature of 400 ° C determines the efficiency of the ashing process, and the upper limit of the temperature of 500 ° C allows you to save ¹³⁷ Cs type radionuclides (cesium-137), which are volatile at a higher temperature, determine the mass of the ash residue of each sample and direct them to a low-background stop to determine α- and β-activity and a semiconductor gamma-ray spectrometer allows you to determine the specific activity of radionuclides of the mineral fraction of dust.

As a result of processing the data recorded in the analytical base, the volume concentration of dust, the specific activity of radionuclides, the effective internal dose of a person and its composition by organic and mineral fractions are determined.

The proposed method of radioecological monitoring of an industrial region makes it possible to achieve the indicated technical result by determining the volume concentration of dust contained in atmospheric air, determining the specific activity of radionuclides in atmospheric air and determining the effective dose of human internal radiation, which did not allow determining the indicated characteristics of atmospheric air by known methods, in particular prototype.

An example implementation of the method.

The inventive method of radioecological monitoring of an industrial region is implemented on the example of Moscow. The specified monitoring is carried out at several stationary posts of radiation control (SPRK) located in various regions of Moscow.

A specific example of the implementation of the method of radioecological monitoring is described for one SPRK.

Sampling was carried out on a Typhoon-type air filter unit with a capacity of 1200 to 3500 m ³ / h, which is installed in a measuring pavilion with blinds on all four walls. Sampling of atmospheric air was carried out on a FPP-15-1.5 / FPA-15-1.5 filter. The blinds selected aerosol particles with a fraction of less than 10 microns, and the filter effectively registered aerosol particles larger than 0.1 microns, thus, aerosol particles with a size in the range from 0.1 to 10 microns that accumulated in the tracheobronchial and olveolar regions of the human respiratory tract were selected, those. biologically significant fraction of dust. The exposure of the filter was carried out continuously for a week, and over the year the number of samples with SPRK was about 50.

Sample preparation of the exposed filter included pressing it into a tablet with a diameter of 50 mm using a PGPR press and weighing it on an analytical balance with an accuracy of 0.01 g.

The tablet is labeled because To monitor the entire territory of Moscow, information is collected from all SPRK posts. The marking of the sample should contain information about the post number, the serial number of the sample, the index of the type of sample, for example: SP1-33-1-05, which means - stationary post number one, the serial number of the sample is 33, 1 - the index of the type of sample is air, according to accepted designation of sample types, 05 - 2005, as well as the date and time of installation and removal of the filter, the volume of air pumped.

The sample was analyzed for the content of natural and technogenic radionuclides on a GENBE-2000 “CANBERRA” semiconductor gamma-spectrometer and the data were entered into an information-analytical database located on a file server.

The sample was milled in a muffle furnace at a temperature of 450 ° С, as a result, the organic component burned out and the ash residue contained a mineral fraction, which was weighed with an accuracy of 0.01 g. The ash residue weight, depending on the time of year of sampling, was from 0.5 g to 10 g, for example, in winter - 0.5 g, in summer - 10 g, in winter the secondary dust lift is blocked by snow cover.

The sample was sent to an NT-1000 "CANBERRA" α-β-radiometer low-background setup to evaluate α- and β-activity, which were respectively

~ 7 · 10 ^-5 and ~ 5 · 10 ^-4 Bq / m ³ , and on a GENTE-2000 "CANBERRA" semiconductor gamma spectrometer for determining the composition of radionuclides ⁷ Be, ⁴⁰ K, ¹³¹ I, ¹³⁷ Cs, ²¹⁰ Pb, ²¹⁰ Po, ²²⁶ Ra, ²³² Th.

The obtained data were entered into the analytical database and the dust concentration, specific activity of radionuclides and the effective internal dose of a person and its composition by organic and mineral fractions were determined from the measurement results.

According to the data obtained, an assessment was made of the radioecological situation in the SPRK area.

A computer program automatically calculated:

1) ρ - volumetric concentration of dust in atmospheric air according to the formula:

where m _i is the mass of aerosol particles, [μg] (total or ash residue) of the i-th dimension;

V _i - the volume of air, [m ³ ] pumped through the filter, i-th dimension;

ρ _i - volumetric concentration of dust, [μg / m ³ ] (full or mineral fraction) of the i-th measurement;

2) c _j - specific activity, [kBq / kg] of the j-th radionuclide of the i-th measurement according to the formula:

where A _j is the activity, [kBq] of the j-th radionuclide in the sample of the i-th dimension (full or mineral fraction);

m _i - mass of aerosol particles, [kg] (total or ash residue) of the i-th dimension;

3) the contribution to the weekly dose of internal radiation exposure of a person of the i-th measurement was calculated by the formula:

where 1,2 is the standard volume of respiration for an adult, m ³ / h;

0.2 - the proportion of the time people were on the street;

168 - the number of hours in a week;

ρ _i - volumetric concentration of dust, [μg / m ³ ] (full or mineral fraction) of the i-th measurement;

dj is the dose coefficient, [Sv / Bq] for the j-th radionuclide [3],

with _j - specific activity, [kBq / kg] j-ro radionuclide.

As an example, the data of one exposure (i-th measurement) obtained on the SPRC are shown.

The volume of air pumped V = 201600 m ³ ;

The mass of aerosol particles accumulated on the filter, m _i = 4.67 g;

The mass of ash residue m _ash. = 4.04 g;

Bulk dust density ρ _i = 23.1 µg / m ³ ;

Bulk density of the mineral fraction of dust ρ _min. = 20.1 μg / m ³ ;

The data obtained for radionuclides samples SPRK are presented in table 1.

Table 1
Data on radionuclides samples with SPRK. Radionuclide c _j , kBq / kg d _j , Sv / Bq D _j , nSv / wk D _j miner, nSv / wk D _j organ., NSv / wk ⁷ Be 3.0 · 10 ^-6 1.3 · 10 ^-10 1.6 · 10 ^-2 1.3 · 10 ^-2 0.3 · 10 ^{-2 40} K 1.2 · 10 ^-6 4.2 · 10 ^-8 2.1 · 10 ^-3 1.8 · 10 ^-3 0.3 · 10 ^{-3 131} I 3.0 · 10 ^-6 1.8 · 10 ^-7 2.2 · 10 ^-2 1.9 · 10 ^-2 0.3 · 10 ^{-2 137} Cs 2.0 · 10 ^-6 1.3 · 10 ^-8 1,0 · 10 ^-3 0.9 · 10 ^-3 0.1 · 10 ^{-3 210} Pb 5.0 · 10 ^-4 3.6 · 10 ^-6 72.5 63.1 9,4 ²¹⁰ Po 6.0 · 10 ^-5 8.8 · 10 ^-6 21.3 18.5 2,8 ²²⁶ Ra 9.910 ^-7 1.5 · 10 ^-6 6.0 · 10 ^-2 5.2 · 10 ^-2 0.8 · 10 ^{-2 232} Th 8.2 · 10 ^-7 4,5 · 10 ^-7 1.5 · 10 ^-2 1.3 · 10 ^-2 0.2 · 10 ^-2

Radioecological monitoring of the industrial region consists in collecting data from all SPRK posts, recording the measurement results in an analytical database located on a file server of the information-analytical system; according to the processing results, an assessment of the radioecological situation is carried out on the basis of a geographic information system by constructing electronic maps of the fields of radiation characteristics and identifying areas of the industrial region with a high content of radionuclides and an effective internal dose of human exposure.

Monitoring data for Moscow in six SPRK are presented in table 2.

table 2
The effective internal dose of a person for a year at the SPRK of Moscow. SPRK numbers SPRK-1 SPRK-2 SPRK-3 SPRK-4 SPRK-5 SPRK-6 Effective human internal dose
μSv / year 5.1 5.8 6.2 5.7 4.9 5,4

The proposed method can be used in any geographical conditions on the territory of any region and allows you to determine the volumetric concentration of dust in the surface layer of atmospheric air at any time of the year and the natural human environment, unlike the prototype, which monitors the radiation state of the territory of the industrial region, but does not determine the volumetric the concentration of dust contained in atmospheric air, and the specific activity of radionuclides in atmospheric air and does not determine the effective dose inside exposure of the person.

When compiling the radiation-hygienic passport of Moscow, the data of the results of radioecological monitoring obtained by the proposed method were used.

Information sources

1. Sobolev I.A. and others. Disposal of radioactive waste at centralized points. M .: Energoatomizdat, 1983, p.105-112.

2. RU 2112999 C1, 05.21.97, publ. BI No. 16 dated 06/10/1998.

3. Radiation safety standards NRB-99. SP 2.6.1.758-99. - Ministry of Health of Russia, 1999.

Claims (1)

A method for radioecological monitoring of an industrial region, including atmospheric air sampling, sample preparation, analysis of samples for the content of natural and technogenic radionuclides, automatic processing of analysis data, direction of prepared samples for evaluating α- and β-activity to a low-background setup, determination of quantitative and qualitative radionuclide content per gamma -spectrometer, recording measurement results in an analytical database located on a file server of the information-analytical system, in which the MS-office package was chosen as the basic set of development tools for this system, the radioecological situation of the industrial region is estimated based on the geographic information system based on the processing results by constructing electronic maps of the radiation characteristics fields and identifying areas of the territory with a high content of radionuclides, characterized in that sampling of aerosol particles of atmospheric air with a fraction of from 0.1 to 10 microns is carried out on an air-filtering unit with a capacity of from 1200 to 3500 m ³ / h, and sample preparation is carried out by weighing the filter of an air-filtration unit with selected aerosol particles from 0.1 to 10 μm after exposure, and then the above analysis of the samples is carried out for the content of natural and man-made radionuclides and automatic processing of the analysis data, after which the samples are ashed in muffle furnace at a temperature of 400-500 ° C, determine the weight of the ash residue of each sample and send them to a low-background setup for evaluating α- and β-activity and to a semiconductor gamma-ray spectrometer for determining the composition of the radionuclides, the obtained data are entered into the analytical database and, based on the measurement results, determine the volume concentration of dust, the specific activity of the radionuclides, the effective internal dose of a person and its composition by organic and mineral fractions, carry out the above assessment of the radioecological situation of the industrial region based on the geographic information system by building maps of fields of radiation characteristics and identification of zones of the territory of an industrial region with a high content of radionuclides s and effective internal dose to humans.