KR102390801B1 - Apparatus for measuring beta-ray in situ and measuring method using the same - Google Patents

Abstract

The present invention relates to a scintillation detection container used in a device capable of measuring beta-rays in the field, an in-situ beta-ray measuring device including the same, and a method for measuring beta-rays using the same. The scintillation detection container of the present invention accommodates a sample of beta-ray emission injected from the outside, a sample receiving part in which scintillation detection by beta-ray derived from the sample is performed, and a space inside the sample receiving part along the flow direction of the sample and at least one inner filling member disposed thereon, wherein the sample receiving part and the inner filling member include a scintillator-containing plastic.

Description

In-situ beta-ray measuring device and in-situ beta-ray measuring method using the same {Apparatus for measuring beta-ray in situ and measuring method using the same}

The present invention relates to an apparatus capable of measuring beta-rays in the field and a method for measuring beta-rays using the same.

Conventionally, most of the analysis methods for beta-emitting nuclides move to a laboratory after collecting a sample, and the analysis is performed in the laboratory. At this time, in the case of nuclides emitting gamma rays, radioactivity is analyzed mainly by using a high purity germanium (HPGe) detector, and in the case of pure beta-emitting nuclides, the sample undergoes physical and chemical pretreatment to convert the sample to a single nuclide. After scintillation, it is analyzed using a liquid scintillation counter (LSC).

As such, the conventional analysis method in the laboratory takes a large amount of time in the process of coming to the laboratory after collecting the sample, and in particular, in the case of sampling for measuring the depth distribution, there is a very high risk that the sample may be disturbed during the collection process. In addition, in the case of pure beta-emitting nuclide, the physical and chemical pretreatment process is very complicated, and it has the disadvantage that it requires a lot of time and manpower.

Therefore, in order to overcome these shortcomings, a method for rapidly analyzing radioactivity in the field is being studied. However, beta-emitting nuclides in radiation monitoring have many limitations in terms of measurement and real-time monitoring compared to gamma-emitting nuclides. For example, gamma rays are photons having no charge and have relatively strong penetrating power compared to beta rays. Therefore, a method has been devised for measuring by constructing a scintillator structure according to the nuclide to be detected using an inorganic scintillator such as NaI(Tl) or CsI(Tl). However, in contrast to this, beta nuclides have a negative charge (-), and accordingly, the reactivity with the medium increases, so that the penetrating power is not good compared to gamma rays. Therefore, most beta-rays are measured using an organic scintillator having a low density (about 1 g/cc) of plastic material.

Specifically, there is a method of using a NaI(Tl) scintillator-based detector as a method for in-situ analysis. However, with this method, it is possible to analyze nuclides accompanying gamma rays along with beta rays, but it is impossible to measure the distribution of radioactivity according to depth. In particular, in the case of pure beta-emitting nuclides, since the beta-rays (reacting distance with the material) are short, they cannot penetrate the protective material of the detection unit, making it impossible to detect them in the field.

Therefore, there is a need for a technology capable of effectively detecting radiation through a pretreatment process suitable for a desired nuclide in the field.

Most laboratories at home and abroad have a disadvantage that secondary waste (organic waste solution) is generated as an organic solvent of solvent material when analyzing beta-nuclide radioactivity. In particular, in the case of radioactive waste made of organic solvent, there is no technology to dispose of it so far.

In addition, the spectrum of beta nuclides in the liquid scintillation counter may overlap with each other. Therefore, when measuring beta nuclides with LSC, chemical separation is absolutely necessary. For this reason, there is a problem in that real-time monitoring of beta nuclides is difficult.

In the case of nuclear facilities, beta-nuclide monitors are installed in the chimneys and entry areas of power plants to monitor them, but they have a disadvantage in that the minimum detection limit is quite high due to problems such as low detection efficiency. It is possible to measure the high concentration of atmospheric beta rays emitted from the inside of the nuclear facility in the event of an accident, but it becomes impossible to measure the secondary air pollution caused by the increase in the amount of leakage from the nuclear facility to the outside.

In a medium, such as a liquid, not a gas, it is difficult to measure due to the low specificity of beta-rays. In addition to diffusion in the atmosphere, there is a problem in that it is not possible to measure according to various sample types such as surface water, groundwater, and seawater in nearby rivers.

Therefore, in order to evaluate the direction of leaked radiation and its risk in the case of an accident in the field of radiation emergency response, environmental monitoring around the facility must be performed and evaluated in a complex manner, such as in the air, rivers, and oceans. It is difficult to evaluate the spread of radiation contamination by monitoring alone.

Such a problem is that, when radioactive contamination exceeding the standard value occurs in the field of accident or decommissioning environmental monitoring of nuclear facilities, it is impossible to analyze underwater beta rays other than the air, so prompt response to accidents and handling of outliers is delayed, and the spread of contamination, etc. can be easily identified. No, even if a sample is collected and analyzed in a laboratory, the real-time radioactivity data status cannot be known because it takes a considerable amount of time for analysis.

An object of the present invention is to provide a measuring device and a measuring method that enable monitoring of radioactivity in real time without generating organic waste.

In one aspect, an object of the present invention is to provide an in-situ beta-ray measuring device and a measuring method that can be applied to a variety of measuring objects using a nearby river, an underground water pipe, an air collector, and the like.

In order to achieve the above object, the present invention according to an aspect includes a sample receiving unit for receiving a sample of beta-ray emission injected from the outside and detecting a scintillation by beta-ray derived from the sample, and a space inside the sample receiving unit A scintillation detection container that can be used in an in situ beta-ray measurement device, comprising at least one inner filling member disposed along the flow direction of the sample, wherein the sample receiving part and the inner filling member include a scintillator-containing plastic provides

The present invention according to another aspect provides an in-situ beta-ray measurement device including the scintillation detection vessel and photomultiplier tubes outside both ends of the scintillation detection vessel.

According to another aspect of the present invention, there is provided a step of injecting a sample of beta-ray emission from the outside into a scintillation detection container, and injecting the sample into at least one of the samples arranged along the flow direction of the sample in the space inside the sample receiving part of the scintillation detection container. It provides a method for measuring beta-rays in situ, comprising the step of sequentially contacting the inner filling member of the sample receiving portion and the inner filling member comprising a scintillator-containing plastic.

By using the in-situ beta-ray measuring device of the present invention, by applying the technology, you can conveniently monitor beta-rays in liquids and gases by installing the equipment directly at the site to be measured, not in the laboratory, and applying remote and automation technology. There are advantages.

In addition, it has two main advantages of not using a liquid scintillator counter (LSC) solution, so that secondary waste is not generated. there is.

The following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical spirit of the present invention together with the above-described content of the invention, so the present invention is limited to the matters described in those drawings It should not be construed as being limited.
1 is a schematic diagram of an in-situ beta-ray measuring apparatus of the present invention according to an embodiment.
Figure 2 shows a scintillation detection container used in the in-situ beta-ray measuring apparatus of the present invention according to an embodiment. Yellow indicates that the plastic material containing the scintillator is, the left side shows that the plastic containing the scintillator is contained in the sample receiving part, and the right side shows that the plastic containing the scintillator is contained in the sample receiving part and the inner filling material.
3 is a cross-sectional view of a scintillation detection vessel used in the in-situ beta-ray measuring apparatus of the present invention according to an embodiment.
FIG. 4 is a Monte Carlo computational simulation graph according to the difference in the with/no fiber of the inner filling material containing the scintillation plastic in the scintillation detection container for each major beta nuclide.
5 is an energy spectrum in which beta nuclides were tested. The left side is the raw measurement value without simultaneous coefficient and dynamic coefficient applied, the middle graph is the energy spectrum to which the synchronization coefficient is applied, and the right graph is the energy spectrum to which the dynamic coefficient is applied.
6 is a multi-energy beta nuclide co-counting energy spectrum.
7 schematically illustrates a cross-section (right) of an in-situ beta-ray measuring apparatus (left) and a scintillation detection container of the present invention according to an embodiment.

The scintillation detection container of the present invention according to an aspect includes a sample receiving unit that receives a beta-ray luminescence sample injected from the outside and performs scintillation detection by beta-ray derived from the sample, and a space inside the sample receiving unit. and at least one inner filling member disposed along a flow direction, wherein the sample receiving part and the inner filling member include a plastic containing a scintillator.

The inventors of the present invention devised an in-situ beta-ray measurement device using a plastic containing a scintillator (hereinafter also referred to as a 'plastic scintillator') as a detection container in order to reduce the amount of organic waste generated by beta-ray measurement. At this time, the problem that beta-ray measurement becomes inaccurate due to the thickness of the plastic scintillator or the contact area between the sample to be measured beta-ray and the scintillator is low was recognized.

Accordingly, in order to increase the accuracy of beta-ray measurement while using a plastic scintillator so as not to generate organic waste, the present invention is devised to increase the contact area between the detection sample and the scintillator by arranging an internal filling member in the sample receiving part of the scintillation detection container. did.

2 shows a cross-section of the sample of the scintillation detection vessel. The cross-section represents a cross-section perpendicular to the flow direction of the sample.

In one embodiment, as shown in FIG. 2 , the sample receiving part of the scintillation detection container may have a circular, oval, or quadrangular cross-section in the flow direction of the sample.

The size of the outer diameter and inner diameter of the sample receiving part may vary depending on the non-determined distance and internal fluid capacity of the beta nuclide, but is not limited thereto.

In one embodiment, when the cross-section of the sample receiving part is circular, for example, the diameter of the sample receiving part matches the size of the detection part such as 1 to 3 inches, and it can be seen that various sizes can be applied according to various types of detectors . As the area of the cross-section increases, the number of detected lights increases and detection efficiency can be increased.

In one embodiment, the at least one inner filling member may have at least one shape among a hollow cylindrical shape, a cylindrical shape, a sheet shape, and a fibrous shape.

3 shows an example of a cross section of the scintillation detection container. In FIG. 3, the colored area indicates the plastic containing the scintillator, and the case in which the inner filling member is a hollow cylinder (1), a cylinder (2), a fiber type (3, 4), and a sheet type (5) shown.

Referring to FIG. 3 , when the inner filling member has a hollow cylindrical shape 1, it may be used as a scintillation detection container for beta-ray measurement of a Kr-85 gas-containing sample having an amorphous diameter of about 3 mm. When the inner filling member has a cylindrical shape (2), it may be used as a scintillation detection container for beta-ray measurement of a sample containing Sr-90 and/or Y-90 liquid emitting high-energy beta-rays. For example, the sample receiving part is prepared to have a thickness of about 1 to 1.5 cm, and Y-90 having a maximum emission energy of 2.3 MeV can be effectively detected. In addition, when the inner filling member is prepared in the form of a sheet 5 , each sheet in the sample receiving unit may be arranged to form a flow path in the form of a slit in order to flow the beta-ray emitting liquid sample.

In the case of using the fibrous inner filling member of FIG. 7, the detection efficiency may be increased by arranging the inner filling members in bundles (3, 4) to closely match the irregularities of each nuclide.

In addition, in the cross section in the flow direction of the sample of the scintillation detection container, the area of the plastic containing the scintillator may be preferably arranged in consideration of the contact area of the sample with the scintillator. For example, the area of the plastic containing the scintillator is not limited thereto because it varies depending on the size, length, thickness, etc. of the scintillation detection container, but as shown in the 3rd and 4th figures of FIG. When one fiber is added, the reaction cross-sectional area of 1 to 2 cm ³ per piece, and in one embodiment, the reaction cross-sectional area of 1.57 cm ³ may be increased. More specifically, the cross-sectional area of a scintillation detection vessel having a thickness of 5 mm and a length of 1 cm with an outer diameter of 2 inches (5.08 cm) is about 32 cm ³ , and when 16 fibers are added by adding 1.57 cm ³ to each fiber, The reaction cross-sectional area can be approximately doubled (32+16*1.57=57.1 cm ³ ).

The plastic scintillator may indicate that the scintillator is put into a plastic polymer and hardened using a polymerization reaction.

In one embodiment, the scintillator is not limited thereto, but may include an inorganic scintillator material, an organic scintillator material, or a mixture thereof. The inorganic scintillator material may be, for example, at least one selected from the group consisting of NaI(Ti), CsI(Ti), Zns(Ag), LiI(EU), CaF ₂ (Eu) and BGO, but is not limited thereto. does not The organic scintillator material may be anthracene, stilbene, or a mixture thereof, but is not limited thereto.

In one embodiment, the plastic is not limited thereto, but may include, for example, one or more polymers selected from the group consisting of polyvinyltoluene and polystyrene.

In an embodiment, the sample receiving unit may include a sample injecting unit and a sample discharging unit, and may be capable of continuously measuring beta-rays. For example, the sample injection unit and the sample discharge unit may be disposed at both ends of the sample receiving unit, respectively. In addition, the sample injection unit and the sample discharge unit may be respectively disposed at the upper end or the lower end at both ends of the sample receiving unit. In addition, in order to improve detection efficiency by increasing a contact area between the sample receiving unit including the plastic scintillator and the internal filling member, when the sample injection unit is disposed at the bottom, the sample discharge unit may be disposed at the top .

In one embodiment, the in-situ beta-ray measuring device may include photomultiplied light (PMT) on the outside of both ends of the scintillation detection container.

The in-situ beta-ray measuring apparatus may use several photodetectors, such as PMT, SiPM, and photodiode, in order to increase detection efficiency in the field.

1 shows the in-situ beta-ray measuring apparatus according to an embodiment. PMT 1, PMT 2, PMT 3, and PMT 4 shown in FIG. 1 may each perform timing coincidence.

In addition, a timing anti-coincidence may be applied to the signal obtained through each of the simultaneous coefficients to prevent overmeasurement due to background radiation and to improve the minimum detection limit.

In the present specification, the '(time) timing coincidence' is a signal processing that recognizes signals that have entered both detectors within a time elapsed by the user and receives only signals with a difference within a certain period of time (several nano seconds) according to a standard. Therefore, electrical noise (ex. PMT noise, etc.) can be minimized.

In the present specification, the '(time) Timing Anti-coincidence' means recognizing signals that have entered both detectors after a time specified by the user, and has a difference of more than time according to a predetermined time (several nano seconds) standard. It is a signal processing technology that receives only a signal, and thus can reduce background radiation.

5 is an experimental value showing the change in the measured value of Tc-99 beta nuclide according to each signal processing technique. The left side shows the raw measurement value without applying the synchronous coefficient and the dynamic coefficient with a criterion of 16 ns. At this time, it can be seen that the PMT noise, Tc-99 beta nuclides, and background radiation are simultaneously measured in the energy spectrum. The graph on the right shows the energy spectrum with the dynamic coefficient applied to the same structure, and it can be seen that only the PMT noise was measured.

In one embodiment, the in-situ beta-ray measuring device may further include a background scintillation detection container for measuring background radiation.

In one embodiment, the in-situ beta-ray measuring apparatus may further include a photomultiplier tube for measuring the background radiation.

In Figure 1, by including another background scintillation detection container surrounding the scintillation detection container carrying the beta-ray emission sample, the background radiation generated from rainwater and soil is counted inversely with the simultaneous counted value to greatly reduce it. In this case, the background scintillation detection container preferably includes a plastic scintillator.

The in situ beta-ray measurement method of the present invention according to an aspect includes injecting a sample of beta-ray emission from the outside into a scintillation detection container, and injecting the sample into a space inside the sample receiving unit of the scintillation detection container along the flow direction of the sample and sequentially contacting the at least one internal filling member disposed thereon, wherein the sample receiving part and the internal filling member include a scintillator-containing plastic.

The scintillation detection container, the sample receiving unit, the inner filling member, and the plastic scintillator refer to the above description.

In one embodiment, the in situ beta-ray measurement method comprises measuring a background radiation of a background scintillation detection vessel for background radiation measurement, wherein the radiation of the sample is measured from the measured background radiation and the radiation measured from the sample of the beta-ray emission. It may include the step of measuring

Measuring the radiation (or beta-ray) is to classify the nuclide by designating a channel value (Region of interest, ROI) desired by the measurer through the application of spectroscopy to energy spectrum the emission of radiation (or beta-ray). can do.

6 shows a multi-energy beta nuclide co-counting energy spectrum (maximum channel about 1600 Ch & 800 Ch). Specifically, FIG. 6 shows energy spectra of a C-14 nuclide (low energy) emitting a maximum energy of about 154 keV and Tc-99 (high energy) emitting a maximum energy of 295 keV. Referring to this, it can be seen that since the difference value of the counted channels can be known, nuclides can be distinguished, thereby enabling the application of beta spectroscopy.

In one embodiment, the method for measuring beta-rays in situ includes injecting a sample of beta-ray emission into the scintillation detection container through a sample injection unit and discharging a sample that has been measured through a sample discharge unit, continuously measuring beta-rays it could be

Claims (16)

A sample receiving unit that receives a sample of beta-ray luminescence injected from the outside and detects scintillation by beta-ray derived from the sample, and
and at least one inner filling member disposed along the flow direction of the sample in the space inside the sample receiving part,
The inner filling member has at least a portion of the sample in a hollow cylindrical shape, a cylindrical shape, or a fiber shape spaced apart from the inner surface of the sample receiving part, disposed along the flow direction of the sample, or in a sheet shape extending from the inner surface of the sample receiving part. is arranged along the flow direction of
The sample receiving portion and the inner filling member will include a scintillator-containing plastic, scintillation detection container.
The method according to claim 1,
The sample receiving unit is a scintillation detection container that has a circular or elliptical cross-section in the flow direction of the sample.
delete The method according to claim 1,
wherein the scintillator comprises an inorganic scintillator material, an organic scintillator material, or a mixture thereof.
5. The method according to claim 4,
The inorganic scintillator material comprises at least one selected from the group consisting of NaI (Ti), CsI (Ti), Zns (Ag), LiI (EU) and BGO.
5. The method according to claim 4,
wherein the organic scintillator material comprises anthracene, stilbene, or a mixture thereof.
The method according to claim 1,
The plastic is a scintillation detection container comprising at least one polymer selected from the group consisting of polyvinyltoluene and polystyrene.
The method according to claim 1,
The sample receiving unit includes a sample injection unit and a sample discharge unit, the scintillation detection container that can measure beta-rays continuously.
9. A scintillation detection vessel according to any one of claims 1, 2 and 4 to 8; and
In-situ beta-ray measurement device comprising photomultiplier light (PMT) outside both ends of the scintillation detection vessel.
10. The method of claim 9,
The in situ beta-ray measurement device further comprising a background scintillation detection vessel for background radiation measurement.
11. The method of claim 10,
In-situ beta-ray measurement device further comprising a photomultiplier tube for measuring the background radiation.
Injecting a beta-ray emission sample from the outside into the scintillation detection vessel according to any one of claims 1, 2, and 4 to 8;
and sequentially contacting the sample with at least one inner filling member of the scintillation detection container.
13. The method of claim 12,
The in-situ beta-ray measurement method of the sample receiving unit in a circular or elliptical cross-section in the flow direction of the sample.
13. The method of claim 12,
The at least one inner filling member has a shape of at least one of a hollow cylindrical shape, a cylindrical shape, a sheet shape, and a fiber shape.
13. The method of claim 12,
measuring background radiation of a background scintillation detection vessel for background radiation measurement; and
In situ beta-ray measurement method further comprising the step of measuring the radiation of the sample from the measured radiation and the measured background radiation from the beta-ray emission sample.
13. The method of claim 12,
The in-situ beta-ray measurement method, comprising the steps of injecting a sample of beta-ray emission into the scintillation detection vessel through a sample injection unit and discharging a sample that has been measured through a sample discharge unit, and continuously measuring beta-rays.

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