RU2296352C1 - Scintillative detecting arrangement - Google Patents

Abstract

FIELD: the proposed scintillative detecting arrangement refers to the field of the environment protection, precisely to the field of registration of radioactive radiation and may be used for radioactive analysis of air and other gaseous mediums.

SUBSTANCE: the given scintillative detecting arrangement allows to determine concentration of radioactive substances in a gaseous medium in each moment of time during the whole time of measuring, to increase accuracy of measuring of the levels of pollution of the gaseous medium and to increase reliability of its work. The proposed arrangement includes a body provided with input and output openings. Inside the body there is a scintillative detector divided by a slit opening consisting of identical upper and low semi-cylinders of an inorganic scintillator and also of upper and low plate of organic scintillator, a photo electronic multiplier connected with its optical window with the scintillative detector, a filtration unit. At that the exterior surfaces of the upper and low plates of the organic scintillator are covered by layers of protecting material. The filtration unit is completely located in the slit opening of the scintillative detector and includes as components a box-shaped body of the inflation unit in whose end walls there are input and output distributing openings and also input and output box-shaped sealing nozzles provided with input and output sockets. At that the filter holds substances capable to tie together volatile gaseous radioactive compounds and is located diagonally inside the box-shaped body of the filtration unit and the input and output box-shaped sealing nozzles are located over the end parts of the box-shaped body of the filtration unit, form with its end walls hermetic gas chambers and hermetically adjoin to the layers of the protective material covering the exterior surfaces of the upper and the low plates of the organic scintillator.

EFFECT: allows to determine concentration of radioactive substances in a gaseous medium.

7 dwg

Description

The inventive scintillation detection device relates to the field of environmental protection, and more specifically to the field of registration of radioactive radiation. It can be used most effectively for radiation analysis of air or other gaseous media.

Known for detecting a gas-flow aerosol monitor "ABPM 301" of the company "MGP Instruments", designed to measure the dose rate of radioactive radiation and determine the concentrations contained in the gas environments of radionuclides during personal monitoring or monitoring of specific areas or zones ("EDGAR system") [1] .

Known gas flow aerosol monitor incorporates a pump, a detecting device (paper cassette filter, semiconductor silicon detector), a detecting unit, as well as a processor and a display device.

The operation of a known gas-flow aerosol monitor consists in pumping a cassette filter through a filter paper of a stream of radioactive gas medium, followed by a semiconductor silicon detector measuring the level of radioactivity of the filter paper with radioactive aerosols trapped on it, after which the measurement results are processed by the processor and displayed on a display device.

The disadvantages of the detection device of a gas-flow aerosol monitor are:

- the impossibility of identification during the detection of mixed types (β + γ, α + β + γ, etc.) of radioactive emissions of their individual (α, β or γ) components, which further processing the measurement results reduces the accuracy of identification of radionuclides;

- the impossibility of identifying different streams of β + γ-radiation with similar characteristics by γ-radiation, but with different

β-radiation characteristics when several such streams of β + γ-radiation fall into the scintillator at the same time, which, when further processing the measurement results, does not make it possible to distinguish from each other radionuclides possessing such types of radioactive radiation.

Known detection device gas scintillation monitor "SAPIG 202" company "MGP Instruments", intended for measuring dose rates of radioactive radiation, determining concentrations, as well as spectral analysis of radionuclides contained in gaseous media ("RAMSYS system") [2].

The known gas-flow scintillation monitor incorporates a gas supply device (pump), a scintillation detection device (aerosol glass fiber filter, iodine filter (zeolite impregnated with a soluble silver salt), NaI (Tl) is a scintillator connected to a photomultiplier), which is connected in series with an electron multiplier), which is connected in series with a unit (processor with a spectral analyzer) and a display device (indicating monitor).

The operation of a known gas-flow scintillation monitor consists in pumping a stream of radioactive gas medium through a fiberglass aerosol filter and an iodine filter for a certain time, as a result of which radioactive aerosols settle and accumulate on the fiberglass filter, and radioactive sorption and accumulation on the iodine filter on zeolite in the form of insoluble silver iodide, the radiation of which is detected by a scintillator.

The disadvantages of the detecting device gas flow scintillation monitor are:

- the impossibility of identification during the detection of mixed types (β + γ, α + β + γ, etc.) of radioactive emissions of their individual (α, β or γ) components, which further processing the measurement results reduces the accuracy of identification of radionuclides;

- the impossibility of identifying different streams of β + γ-radiation with similar characteristics for γ-radiation and different characteristics for β-radiation with the simultaneous hit of several such flows of β + γ-radiation inside the scintillator, which during further processing of the measurement results does not allow to distinguish from each other radionuclides with these types of radioactive emissions.

The closest in technical essence to the claimed is a scintillation detecting device [3], which includes a body of scintillation detecting device equipped with inlet and outlet openings, inside of which there is a scintillation detector covered with a reflector and separated by a slot, consisting of the same upper and lower half-cylinders of inorganic scintillators their bases the same upper and lower plates of the organic scintillator, multiply photoelectron A filter, connected by its optical window to the scintillation detector, and also located in the slotted hole of the scintillation detector and extending beyond its limits, a filtration unit containing a filter made in the form of a movable tape.

The known device operates as follows.

First, for a fixed time (usually within 24 hours), the analyzed gaseous medium (air or other gas) is pumped through a specific section of the filter located outside the slot of the scintillation detector, as a result of which radioactive aerosols are fixed on this section of the filter. Then the filter is set in motion, a section of the filter with radioactive aerosols fixed on it is moved to the slit hole of the scintillation detector, after which the filter is stopped and the radiation is detected using the scintillation detector. The light pulses (flashes) generated in the scintillation detector through the optical window of the photomultiplier are fed into the photomultiplier, where they are converted into electrical pulses, which are further processed in special electronic units and converted into dose rates or other indicator of radioactive radiation.

The disadvantages of the known scintillation detection device with such a design of the filtration unit are:

- the possibility of conducting only periodic measurements of a certain average (for every 24 hours) level of contamination of the gaseous medium, i.e. the impossibility of determining the concentrations of radioactive substances in a gaseous medium at any time during the entire measurement time;

- reduced accuracy of measuring the level of contamination of the gaseous medium, due to the fact that during its pumping through the filter section there will be a partial decay of the short-lived radionuclides fixed on it, as well as the inability of the filter to retain volatile radioactive gaseous compounds;

- reduced reliability, due to the fact that when the failure of the element that provides the movement of the filter, the scintillation detection device will cease to work.

The advantages of the inventive scintillation detecting device are the ability to determine the concentration of radioactive substances in a gaseous medium at any time during the entire measurement time, improving the accuracy of measuring the level of contamination of a gaseous medium and increasing the reliability of its operation.

These advantages are achieved due to the fact that the inventive scintillation detecting device includes a body of scintillation detecting device equipped with inlet and outlet openings, inside which are located a scintillation detector covered with a reflector and separated by a slot, consisting of identical upper and lower half-cylinders of an inorganic scintillator adjacent to them top and bottom plates of an organic scintillator, whose outer surfaces x are covered with layers of a protective material freely transmitting α, β, γ and neutron radiation (for example, with any polymer films satisfying this requirement), a photomultiplier connected by its optical window to a scintillation detector, and a unit located entirely in the slot hole of the scintillation detector filtration system, comprising a filter and including a box-shaped housing of a filtration unit, in the end walls of which there are inlet and outlet distribution openings provided with inlet and outlet m nozzles inlet and outlet box-shaped sealing nozzles, and the filter contains substances that can bind volatile gaseous radioactive compounds, and is diagonally located inside the box-shaped housing of the filtration unit in such a way that it separates cavities from each other, the first of which is bounded on one side by an end wall box-shaped housing with inlet distribution holes, and the other is bounded on one of its sides by the end wall of the box-shaped housing with output distribution holes s, and the inlet and outlet box-shaped sealing nozzles are located on top of the end parts of the box-shaped case of the filtration unit, form hermetic gas chambers with its end walls and hermetically adhere to layers of protective material covering the outer surfaces of the upper and lower plates of the organic scintillator.

Distinctive features of the claimed scintillation detecting device is that

- the outer surfaces of the upper and lower plates of the organic scintillator are covered with layers of protective material that freely transmit α, β, γ and neutron radiation;

- a filtration unit containing a filter is entirely located in the slotted hole of the scintillation detector and includes:

1. the box-shaped housing of the filtration unit, in the end walls of which there are inlet and outlet distribution holes;

2. box-shaped inlet and outlet sealing nozzles equipped with inlet and outlet nozzles;

- the filter contains substances capable of binding volatile gaseous radioactive compounds, and is located inside the box-shaped housing of the filtration unit in such a way that it separates cavities, the first of which is bounded on one side by the end wall of the box-shaped housing with inlet distribution openings, and the other is limited on one of its sides the end wall of the box-shaped housing with outlet distribution openings;

- the inlet and outlet box-shaped sealing nozzles are located on top of the end parts of the filtration unit body, form sealed gas chambers with its end walls and are hermetically adjacent to the layers of protective material covering the outer surfaces of the upper and lower plates of the organic scintillator.

The inventive scintillation detecting device in the embodiment with a diagonal filter in the filtering unit is shown in Fig.1-7.

In Fig. 1, a front view shows in section a box-shaped housing of a filtration unit with inlet and outlet distribution openings and a filter diagonally located therein;

Figure 2 is a top view of a sectional box-shaped housing of the filtration unit with inlet and outlet distribution holes (without filter);

In Figs. 3 and 4, a front view and a top view show in section one of the box-shaped sealing nozzles with a nozzle (the other box-shaped sealing nozzle with a nozzle is absolutely identical to the first);

In Fig. 5, a front view is a sectional view of the entire filtration unit;

Figure 6 is a front view showing a cross-section of a scintillation detecting device with a filtration unit located therein;

Figure 7 is a top view of a sectional scintillation detection device with a filtration unit located therein (without filter).

The inventive scintillation detecting device includes a box-shaped housing of the filtration unit 1, inlet distribution openings 2, outlet distribution openings 3, a filter 4, an inlet box-shaped sealing nozzle 5, equipped with an inlet pipe 6, a sealed gas chamber 7, an outlet box-shaped sealing nozzle 8, equipped with an outlet pipe 9 , a sealed gas chamber 10, a layer of protective material 11 of the upper plate of the organic scintillator, the upper plate of the organic scintillator 12, the upper half Lindgren inorganic scintillator 13, the protective material layer 14 of the lower plate organic scintillator, an organic scintillator bottom plate 15, the lower half-cylinder inorganic scintillator 16, the reflector 17, the housing of the scintillation detection unit 18, a photomultiplier 19, optical window 20 comprising a photomultiplier.

The inventive scintillation detection device operates as follows.

After installing the filtration unit in the slotted hole of the scintillation detector, the outlet pipe 9 is connected to a bleed ventilation system, which allows the pumping of a gaseous medium (in this case, air) through the inlet pipe 6, a sealed gas chamber 7, inlet distribution holes 2, filter 4, output distribution holes 3 a sealed gas chamber 10 and an outlet pipe 9, the sealed gas chambers 7 and 10 and the tightness of the fit of the inlet and outlet box-shaped sealing nozzles 5 and 8 to the layers The protective material 11 and 14 reliably isolate the internal volume of the filtration unit from the environment, and the layers of protective material 11 and 14 protect the surfaces of the upper and lower plates of the organic scintillator 12 and 15 from pollution by aerosols.

After that, voltage is applied to the photomultiplier tube 19 and the scintillation detection device begins to detect the radioactive radiation of the radionuclides held up by the filter 4, and the radioactive aerosols are mechanically delayed by the filter 4, volatile gaseous radioactive compounds are fixed on the filter 4 due to the presence of substances capable of binding them, for example solid sorbents such as activated carbon, zeolite, silica gel, etc., and the presence in the end walls of the box body of the filter assembly Station 1 of the inlet and outlet distribution openings 2 and 3 ensures uniform distribution of the delayed radioactive substances over the entire surface of the filter 4.

The most optimal embodiment of the filtration unit of the scintillation detecting device, in which almost 100% of the areas of the upper and lower plates of the organic scintillator 12 and 15 are involved in the detection, and the filter surface has a maximum area compared to other options for its location inside the filter unit housing, is , wherein:

- the box-shaped housing of the filtration unit 1 has a shape that matches the shape of the plates of the organic scintillator 12 and 15 with an internal horizontal section equal to the area of the plates of the organic scintillator;

- the filter 4 is made in the form of a flat plate and is diagonally located inside the box-shaped housing of the filtration unit 1.

The specified design of the filtration unit provides:

- the continuity of measuring the level of contamination of the analyzed gaseous medium during its pumping, which, when processing the detection results, makes it possible to determine the concentration of radioactive substances in it at any time during pumping, i.e. makes it possible, for example, to determine the moment of an unforeseen emergency release of radioactive aerosols or volatile gaseous substances into the atmosphere;

- measurement of the level of contamination of the analyzed gaseous medium with greater accuracy due to the possibility of determining the content in it of the fraction of the radioactive component of short-lived radionuclides;

- improving the reliability of the entire scintillation detection device as a whole due to the absence of moving parts in it,

and the design of the filter improves the accuracy of measuring the level of contamination of the analyzed gaseous medium due to the possibility of determining the content in it of the fraction of the radioactive component of volatile gaseous radioactive substances.

LITERATURE

1. "MGP Instruments: a complete range of equipment for radioactivity and chemical toxicity", 1997 catalog, "MGP Instruments Inc." 5000 Highlands Parkway, Suite 150 Smyrna, Georgia 30082, s.VII-VIII, 9.

2. "MGP Instruments: a complete range of equipment for radioactivity and chemical toxicity", 1997 catalog, "MGP Instruments Inc." 5000 Highlands Parkway, Suite 150 Smyrna, Georgia 30082, s. 27.

3. RU 2262721 C1, IPC ⁷ G 01 T 1/20, op. 10/20/2005, Bull. No. 29.

Claims (1)

A scintillation detecting device, comprising a body of a scintillation detecting device provided with inlet and outlet openings, inside of which there is a scintillation detector covered with a reflector and separated by a slot, consisting of the same upper and lower half-cylinders of an inorganic scintillator, adjacent to them are identical upper and lower photoelectron plates, respectively; a multiplier connected by its optical window to scintillation det a filtering unit comprising a filter located in the slotted hole of the scintillation detector, characterized in that the outer surfaces of the upper and lower plates of the organic scintillator are coated with layers of protective material that freely pass α, β, γ and neutron radiation, a filtration unit containing a filter, entirely located in the slotted hole of the scintillation detector and incorporates a box-shaped housing of the filtration unit, in the end walls of which there are input and output distribution the aperture, as well as box-shaped inlet and outlet nozzles equipped with inlet and outlet nozzles, the filter containing substances capable of binding volatile gaseous radioactive compounds and is diagonally located inside the box-shaped housing of the filtration unit, and the inlet and outlet box-shaped sealing nozzles are located on top of the end parts of the box-shaped housing filtration unit, form with its end walls sealed gas chambers and hermetically adhere to layers of protective material, covering m external surface of the upper and lower plates of the organic scintillator.

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