RU176245U1 - Radiometer of equivalent equilibrium volumetric activity of radon - Google Patents

Abstract

The utility model relates to the field of radiation measurements of natural radionuclides, to provide control over the radiation situation in industrial enterprises and in the residential sector, sanitary-epidemiological) assessment of radiation doses to personnel and the public, and to carry out scientific research. A radiometer of equivalent equilibrium volumetric activity of radon, in order to increase the accuracy of measurements of equivalent equilibrium volumetric activity of radon and thoron, taking into account the estimate of the fraction of the non-aligned fraction of their daughter products, necessary for estimating the absorbed and effective doses of radiation for personnel of radiation-hazardous industries and the population, provides direct air sampling without any distortion of its flow directly to the measuring filters (analytical aerosol or diffusion) by installing diffusion filter on the pressure ring of the aerosol filter. 3 ill.

Description

The utility model (PM) relates to the field of radiation measurements of natural radionuclides, monitoring the radiation situation in industrial enterprises and in the residential sector, sanitary-epidemiological) assessing the effective dose of radiation to personnel and the public, and conducting research.

The radiometer of equivalent equilibrium volumetric activity of radon is designed to measure the equivalent equilibrium volumetric activity (ERAA) of radon and thoron, as well as to determine the fraction of non-aeronolized fractions of the daughter products of radon (DPR) and thoron (DPT) in the air of various premises (mines, tunnels, bunkers and other underground structures, residential, public and industrial buildings).

The PM is a spectrometric type radiometer (Fig. 1), which has two independent measurement channels (1), one of which is equipped with an aerosol analytical filter, the other are additionally equipped with diffusion filters, a control unit (2), a display (3) and a control keyboard ( four). The determination of the fraction of the non-attached fraction and the fraction of the fraction attached to aerosols is achieved by the difference effect between the readings of these measuring channels.

In FIG. 2 is a drawing of the measurement unit and direct sampling of the analyzed air (without distortion of its flow). The block consists of a semiconductor detector (5), a stepper motor (6), an air pump (7), a flow meter (8), diffusion (9) and aerosol filters (10) with a funnel (11). PM provides a direct flow of analyzed air (12) through diffusion and aerosol filters.

Directly direct air sampling is carried out according to FIG. 2 by installing an aerosol filter 10 on the funnel 11 through a sealing gasket. The filter is fixed by a clamping ring. If it is necessary to measure the unattached fraction of daughter products, a diffusion filter (9) is mounted on the clamping ring.

The unattached fraction of daughter products is selectively deposited in the radiation-sensitive area of the respiratory tract. The initial data on the fraction of the non-aligned DPR fraction in the ERAA of radon, obtained using a radiometer during the measurement process, is used in calculating the absorbed or effective radiation dose to personnel of radiation-hazardous objects and the population. This PM allows you to provide a new promising direction in the implementation of radiation monitoring and radiation assessment of research objects at the effective dose in the system of domestic measurements.

The radiometer can provide operation in three measurement modes: automatic (sampling 180 s, measuring 200 s), monitoring (a series of discrete measurements after 4 hours) and manual (sampling time up to 600 s, measurement selection time up to 10000 s).

The radiometer (PM) is primarily intended for professional use. It can be in demand when solving such issues as: assessment of radiation levels (doses), expert measurements, monitoring of radiation conditions, the use of metrological measurements as a comparator in practice, to ensure the preparation of facilities for the construction part of radon-protective measures, for scientific research and many others applied tasks of radiation control.

A common feature in the design of measuring instruments for radon daughter products is the absence of requirements for the need for direct, without distorting the flow of the analyzed air, sampling for measuring filters (diffusion or aerosol), which leads to a distortion of the measurement results and a significant underestimation of the estimates of the absorbed and effective doses of personnel and population.

As an example in FIG. 3 is a diagram of a radiometer (patent U.S. Patent Oct. 16, 1990 4,963,730) for measuring the volumetric activity of daughter products of radon and the non-aligned fraction of DPR to aerosols. In its housing (13) are located: radiation detectors (5), an air pump (7), diffusion (9) and aerosol filters (10) and three chambers: inlet (16) with an opening (17) for air intake (12) with protective cover (18) and intermediate (19) measuring chambers, as well as exhaust (20).

This diagram clearly illustrates the distortions of air flows indicated by arrows (12) during the passage of both a diffusion filter (9) and an aerosol filter (10). On the surfaces of the measuring chambers, unaccounted deposition of both the unconnected fraction of the DPR and their aerosol component occurs, which also depends on the dispersed composition of the studied air.

In order to quantify the distortion of the measurement results, in 2015, the work of the domestic radar analyzer ERAA of RAA-3-01 AlfaAERO (State Register of Measuring Instruments No. 37973-08 of June 25, 2008) in the premises of a radiation-hazardous facility was considered. This radiometer structurally also has a distortion of the air flow during sampling, as the considered patented model.

It was found that the readings of the ERAA of radon were underestimated by 20% with respect to the claimed PM, as it turned out to be exactly the share of the non-aligned fraction of the daughter products of radon, which creates the bulk of the effective radiation dose.

The discrepancy of 20% in the total level of EERA of radon between the indicated radiometer and PM is not so significant. However, the loss of a 20% EERA of radon in the form of an unattached fraction for estimating the radiation dose was very critical, as it was equivalent to its 5-fold underestimation.

The considered PM lacks such a drawback. Its advantage is the absence of the indicated losses in the activity of daughter products caused by deficiencies in sampling of the air under study due to their deposition on the surfaces of structural parts with curved air flow and turbulent turbulence.

It was found that even slight distortions in the directions of air flow during sampling significantly affect the loss of activity of the unconnected fraction of the DPR, and therefore on the estimates of the radiation situation and radiation dose.

Claims (1)

Radiometer of equivalent equilibrium volumetric activity of radon, characterized in that, in order to increase the accuracy of measurements of equivalent equilibrium volumetric activity of radon and thoron, taking into account the estimates of the fraction of the non-attached fraction of their daughter products, which is necessary when estimating the absorbed and effective doses of radiation to personnel of radiation hazardous industries and the public, direct air sampling is provided without any distortion of its flow directly to the measuring filters (analytical aerosol or diffusion) Fitting eat diffusion filter on the compression ring aerosol filter.

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