Radiation monitoring apparatus and method using single scintillator and doi method

Abstract

The present invention provides an apparatus and a method capable of monitoring radiation in all directions in real time by measuring a radiation dose incident on a scintillator through slots of multiple collimators having different heights and having slots facing different directions and classifying the radiation dose according to the height to detect the radiation dose incident in each direction.

Description

Radiation monitoring device and method using single scintillator and DOI method

[0001] The present invention relates to a radiation monitoring device and method using a single scintillator and a DOI (Depth of interaction) method, and by utilizing the difference in signal values ​​measured by a plurality of optical sensors according to a height difference, the direction of radiation can be detected, thereby enabling real-time omnidirectional radiation monitoring.

[0002] Radioactive material monitoring systems are essential to prevent potential environmental and health risks arising from accidents at nuclear facilities or radiation application facilities. They are also crucial for early detection of radioactive material leaks or contamination, enabling rapid response. The government aims to protect public health and preserve the national environment by providing the information necessary for early detection of radioactive abnormalities and establishing appropriate countermeasures. The National Environmental Radiation Automated Monitoring Network (IERNet) monitors radioactive materials using environmental radiation monitors at 194 radiation monitoring stations nationwide.

[0003] To quickly and efficiently detect radioactive materials, the use of surveillance systems capable of detecting the direction of the source is essential. Various methods are currently being developed. Specifically, gamma cameras offer the advantage of real-time monitoring in a specific direction. However, their field of view is limited, and rotation is required for omnidirectional detection, making real-time omnidirectional detection impossible. Furthermore, multiple gamma cameras are required for real-time omnidirectional detection.

[0004] Also, a rotating collimator can collect radiation from multiple angles depending on the rotation, and can be composed of a single scintillator, but since measurements are made while rotating the collimator, there is a disadvantage in that real-time detection in all directions is impossible. When a radiation sensor detects a specific type of radiation, a surveillance system that uses the coefficient difference to analyze the difference in the coefficient to track the radiation level in the environment and generate an alarm is utilized, but it has a complex structure composed of nine scintillators, and there is a disadvantage in that real-time detection is impossible because multiple sources cannot be detected at the same time.

[0005] The nuclear fuel automatic verification device of the radiation detection system presented in Korean Patent No. 10-0959781 comprises: a radiation detection sensor installed at one end of a cable to detect the intensity of radiation emitted from a nuclear fuel bundle stacked vertically in an underwater storage tank; a drive unit installed inside the main body to move the cable so that the radiation detection sensor can be raised and lowered into the underwater storage tank; a position detection sensor that detects the vertical position of the radiation detection sensor raised and lowered by the drive unit; And a control unit that calculates the number of nuclear fuel bundles within a vertical measurement section of an underwater storage tank from information on the position of a radiation detection sensor detected by a position detection sensor and information on the radiation intensity detected by the radiation detection sensor, wherein the control unit divides the vertical measurement section of the underwater storage tank into a plurality of divided sections such that each section includes one nuclear fuel bundle, determines whether a peak point of the radiation intensity exists within each divided section from signals transmitted from the position detection sensor and the radiation detection sensor, and calculates the number of divided sections in which the peak point exists, thereby calculating the number of nuclear fuel bundles stacked in the vertical direction within the measurement section of the underwater storage tank. However, since the driving amount of a rotating roller is measured through an encoder and the height according to the driving amount is detected to measure the radiation dose by height, multiple measurement processes must be performed by driving the rotating roller through a driving motor in order to monitor the radiation, and a method for monitoring the radiation by height or direction at the same time is not presented.

[0006] Korean Patent No. 10-2613228 discloses a technology in which a coded aperture-based radiation (gamma ray and double particle) image fusion device (hereinafter referred to as “image fusion device”) arranged in a radial structure along a 360° circumference is mounted on a driving device (an unmanned robot including an environmental monitoring vehicle, a forklift, or a quadruped robot) to enable panoramic (around view) stereoscopic detection in all directions, so that it can perform constant surveillance and monitoring while driving (operating) in rough terrain, airports, ports, nuclear power plants, or buildings or areas where radiation exposure is expected. However, since multiple radiation cameras must be installed, there is a problem in that the structure is complicated and the manufacturing cost increases.

[0007] Korean Patent No. 10-2361539 discloses a radiation monitoring device including a plurality of detectors arranged on the perpendiculars of each face forming a regular polyhedron to detect radiation, a signal processing unit that compares energy information acquired from the detectors to determine a detection order, a signal acquisition unit that acquires detection positions and detection energy information of radiation from each detector based on the determined detection order, and an image display unit that displays a radiation distribution image based on the detection positions and detection energy information of radiation. However, this is a technology for acquiring a radiation distribution image of a specific space using a plurality of detectors, and has a problem in that it does not suggest a method for monitoring radiation from multiple directions in real time using a single detector.

[0008] Korean Patent No. 10-2236154 proposes an angle-variable collimator, which includes a plurality of hole plates, each of which has a plurality of unit holes formed on its respective plate surface, and which are stacked in the plate surface direction, and a plate driving unit that adjusts the spacing between the plurality of hole plates in the stacking direction; the unit holes at mutually corresponding positions between the hole plates are communicated along the stacking direction to form incident holes of radiation in the stacking direction; the spacing between the adjacent unit holes of each of the hole plates increases as the stacking direction progresses so that the incident holes are formed such that the inclination angles increase as they approach the edges of the hole plates; and the plate driving unit adjusts the spacing between the hole plates to adjust the inclination angles of the incident holes. However, there is a problem in that it only allows for adjustment of the diffusion angle and the focusing angle, and does not suggest a method for monitoring radiation from multiple directions.

[0009] The purpose of the present invention is to solve such problems, and the present invention provides a radiation monitoring device capable of monitoring nuclide and direction information for multiple radiation sources in real time in all directions (360 degrees) through a single device using a single scintillator.

[0010] In addition, the present invention provides a radiation monitoring method capable of monitoring radiation in all directions in real time.

[0011] According to one aspect of the present invention, the present invention provides a radiation monitoring device comprising: a scintillator; a plurality of optical sensors provided at both ends of the scintillator; a simultaneous counter connected to the plurality of optical sensors; a measuring unit that detects and classifies signals generated from the optical sensors into height-specific signals through the simultaneous counter and outputs them; an analyzing unit that analyzes at least one of a radioactive nuclide, an incident direction of the radioactive radiation, and the presence or absence of the radioactive radiation using data received from the measuring unit; and a collimator that is provided in a form that surrounds the outside of the scintillator, wherein the collimator is provided with a plurality of slots that can each pass an external radiation source through the scintillator, wherein the plurality of slots are respectively provided at different heights, and the directions in which each of the plurality of slots is formed are different.

[0012] According to another aspect of the present invention, the present invention provides a radiation monitoring method including the steps of: 1) irradiating a gamma ray into a scintillator through each slot of a collimator formed to face different directions; 2) classifying a signal measured through a first light sensor and a second light sensor provided at both ends of the scintillator into a preset range section according to a difference in the amount of light collected by the first light sensor and the second light sensor; 3) determining a response height of the scintillator for each classified range section; 4) forming an energy spectrum for each determined response height; and 5) outputting direction information of a radiation source according to the formed energy spectrum.

[0013] The present invention utilizes only a single scintillator and can monitor radiation in all directions with a single device, thereby simplifying the system and reducing costs.

[0014] The present invention is capable of monitoring radiation in all directions in real time by measuring and classifying in real time the difference in the amount of light collected by the light sensors located at both ends of a single scintillator according to the height of the slots facing different directions of the collimator.

[0015] Figure 1 is a drawing showing the combined structure of a scintillator, a light sensor, and a collimator having slots facing different directions.

[0016] Figure 2 is a drawing showing an example in which radiation is converted into light energy through a scintillator and counted through a simultaneous counter connected to each light sensor to output the nuclide of radiation and the direction of incidence of radiation.

[0017] Figure 3 is a diagram showing measurement results according to the energy spectrum measured at various angles.

[0018] Figure 4 is a diagram showing an example of identifying nuclides based on energy spectrum.

[0019] Figure 5 is a flow chart showing the overall flow of the radiation monitoring method of the present invention.

[0020] Figure 6 is a diagram showing the configuration of a detector that performs a GATE computer simulation to verify whether the reaction position (height) of an incident gamma ray changes depending on the direction of the radiation source.

[0021] Figure 7 is a diagram showing the results of GATE computational simulation.

[0022] Figure 8 is a drawing showing the results of an optical computer simulation performed using DETECT2000 to verify whether the ratio of photon collection amounts at both ends changes depending on the reaction height.

[0023] Figure 9 is a drawing showing the results of verifying whether there is a difference in the amount of photons collected by the light sensor depending on the location of photon generation within the cross-section of the scintillator.

[0024] FIG. 10 is a drawing showing the results of confirming that the collection ratio of the light sensor is differentiated according to the height of photon generation using the device and method of the present invention.

[0025]

[0026] In order to fully understand the present invention, its operational advantages, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the contents described in the drawings, which illustrate preferred embodiments of the present invention.

[0027] The expressions “includes,” “consists of,” “has,” etc., which may be used hereinafter, should be understood to not exclude additional components or functions.

[0028] Expressions such as “first…”, “second…”, “first”, “second”, etc., which may be used hereinafter, should not be construed as limiting the order or importance of components, unless explicitly stated otherwise.

[0029] The term "~unit" that may be used hereinafter includes a unit realized by hardware, a unit realized by software, and a unit realized using both. In addition, one unit may be realized by using two or more pieces of hardware, and two or more units may be realized by one piece of hardware. Meanwhile, the "~unit" is not limited to software or hardware, and the "~unit" may be configured to be in an addressable storage medium or may be configured to reproduce one or more processors. Accordingly, as an example, the "~unit" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within the components and "~units" may be combined into a smaller number of components and "~units" or further separated into additional components and "~units." Additionally, components and '~parts' may be implemented to regenerate one or more CPUs within a device or secure multimedia card.

[0030] In the use of terms below, singular expressions should be understood as not excluding plural expressions unless explicitly stated otherwise.

[0031] Hereinafter, the present invention will be described in detail by describing preferred embodiments thereof with reference to the attached drawings. The same reference numerals in each drawing represent the same components.

[0032] Referring to FIGS. 1 to 4, the present invention provides a radiation monitoring device comprising: a scintillator; a plurality of optical sensors provided at both ends of the scintillator; a simultaneous counter connected to the plurality of optical sensors; a measuring unit that detects and classifies a signal generated from the optical sensors into a height-based signal through the simultaneous counter and outputs the same; an analyzing unit that analyzes at least one of a radioactive nuclide and the presence or absence of radiation using data received from the measuring unit; and a collimator that is provided in a form that surrounds the outside of the scintillator, wherein the collimator is provided with a plurality of slots that can each pass an external radiation source through the scintillator, and wherein the plurality of slots are respectively provided at different heights and the directions in which each slot is formed are different.

[0033] The above-mentioned optical sensor may be any one of a photomultiplier tube (PMT), a silicon photomultiplier (SiPM), a photodiode (PAD), and an avalanche photodiode (APD), and may be specifically a photomultiplier tube (PMT), but is not limited thereto.

[0034] Depending on the height at which the scintillator reacts, a difference in the amount of light collected (electrical signal) is generated at the two end photosensors. The sum of the two signals provides information on the energy of the gamma ray, and the ratio of the two signals provides information on the response height (DOI).

[0035] The above simultaneous counting unit may include a simultaneous counting circuit that is a circuit that outputs a true logic value when the logic values ​​of all inputs match true, and may be characterized by converting an electric signal generated from a light sensor into a digital signal, classifying the difference value of the amount of light collected measured by the light sensors at both ends of the converted digital signal according to a preset range, and counting the radiation dose for each range.

[0036] The collimator may be provided in a polygonal or circular shape, which surrounds the outside of the scintillator and has a plurality of slots, each of which can pass an external radiation source through the scintillator. When the collimator of the present invention is provided in a polygonal shape, it may be provided in an n-gonal shape depending on the number of slots (n), but is not limited thereto. In addition, the collimator may be provided in the form of one or more collimators having a plurality of slots formed in different directions.

[0037] The slots formed in the collimator can be defined as 360 / the number of collimators (n) = the angle of the slot to monitor in all directions. As the angle of the slot decreases, the angular resolution increases, but the sensitivity decreases because the amount of gamma radiation incident through the slot decreases. Therefore, the number of collimators may be 2 to 12, more specifically 4 to 10, and even more specifically 8, but is not limited thereto, and the number of collimators and the angle of the slots may be determined in various ways depending on the purpose of use and the radiation dose of the area to be measured.

[0038] The above analysis unit may be characterized by further comprising a nuclide determination unit that determines a nuclide by using at least one of a peak position, a count density, and an area value of the data received from the measurement unit. Referring to Drawing 4, the nuclide may be determined by using a peak value according to the energy spectrum in each slot, but is not limited thereto, and the nuclide may also be determined by using a count density and an area value unique to each nuclide.

[0039] According to another aspect of the present invention, the present invention provides a radiation monitoring method including the steps of: 1) irradiating a gamma ray onto a scintillator through a collimator having a plurality of slots formed in different directions; 2) classifying a signal measured through a first light sensor and a second light sensor provided at both ends of the scintillator into a preset range section according to a difference in the amount of light collected by the first light sensor and the second light sensor; 3) determining a response height of the scintillator for each classified range section; 4) forming an energy spectrum for each determined response height; and 5) outputting direction information of a radiation source according to the formed energy spectrum.

[0040] Referring to Fig. 5, gamma rays are incident on the slots of the collimator, and the scintillator emits them as photons. The amount of photons emitted can be measured through the optical sensors provided at both ends of the scintillator, and a coincidence counter is connected to each optical sensor to individually count the radiation dose incident through the slots of the collimator provided at different heights. Since each collimator is provided at a different height, when the signals collected from each collimator are measured through the first optical sensor and the second optical sensor, a difference occurs according to the height, and this can be calculated as a specific ratio (see Fig. 10). According to this difference in ratio, the radiation information measured by height can be divided into sections and classified, and consequently, radiation information according to angle can be calculated. Fig. 10 is a drawing showing the results of confirming that the collection ratio of the optical sensor is distinguished according to the photon generation height, and according to this difference, radiation information according to height (and consequently, according to angle) can be classified. That is, the collection ratio of the light sensor according to the height can be classified according to the preset section and calculated as radiation information for each height, and the section of the light sensor collection ratio can vary depending on the size of the scintillator used, the number and height of the collimator, etc., and can be individually measured and set in advance by the user.

[0041] The first and second light sensors may be characterized by being any one of a photomultiplier tube (PMT), a silicon photomultiplier (SiPM), a photodiode (PAD), and an avalanche photodiode (APD), and specifically, the first and second light sensors may be characterized by being a photomultiplier tube (PMT).

[0042] In addition, the step 5) may be characterized by further including a step of determining a nuclide by using at least one of a peak position, a coefficient density, and an area value of the data, and specifically, it may be a peak position of the data, but is not limited thereto.

[0043] Referring to Fig. 9, the inventors designed and conducted an experiment to verify whether there was a difference in the amount of photons collected by the optical sensor depending on the location of photon generation within the cross-section of the scintillator. As a result, it was confirmed that there was no significant difference in the amount of photons generated depending on the location (center and side) within the cross-section of the scintillator. Therefore, it is possible to measure radiation at different angles without being affected by errors depending on the cross-sectional location of photons within the scintillator.

[0044] According to another aspect of the present invention, there is provided a radiation monitoring method, comprising: analyzing a radiation incidence direction using a plurality of radiation monitoring devices of the first claim; and determining a point where two or more lines extending toward the analyzed radiation incidence direction intersect as a region where a radioactive source exists. Referring to FIG. 11, with one device, only the directionality of the radiation source can be determined, but when two or more devices are used, the point where virtual lines extending along the measured radiation incidence direction intersect can be determined as the location of the radiation source. In this case, when a large number of slots are formed, the resolution increases, enabling more accurate location confirmation, but the amount of gamma radiation incident through the slots decreases, resulting in lower sensitivity. Therefore, the number of slots can be determined based on the expected distance from the radiation source and various other factors.

Claims

1. A radiation monitoring device comprising: a scintillator; a plurality of optical sensors provided at both ends of the scintillator; a simultaneous counter connected to the plurality of optical sensors; a measuring unit that detects and classifies signals generated from the optical sensors into height-specific signals through the simultaneous counter and outputs them; an analyzing unit that analyzes at least one of a radioactive nuclide, an incident direction of radiation, and the presence or absence of radiation using data received from the measuring unit; and a collimator provided in a form that surrounds the outside of the scintillator, wherein the collimator is provided with a plurality of slots that can each pass an external radiation source through the scintillator, wherein the plurality of slots are respectively provided at different heights, and the directions in which the plurality of slots are formed are all different.

2. A radiation monitoring device according to claim 1, wherein the optical sensor is one of a photomultiplier tube (PMT), a silicon photomultiplier (SiPM), a photodiode (PAD), and an avalanche photodiode (APD).

3. A radiation monitoring device according to claim 1, characterized in that the light sensor is a photomultiplier tube (PMT).

4. In the first paragraph, the simultaneous counting unit converts an electric signal generated from a light sensor into a digital signal, classifies the difference value of the amount of light collected measured by the light sensors at both ends of the converted digital signal according to a preset range, and counts the radiation dose for each range. A radiation monitoring device.

5. A radiation monitoring device according to claim 1, wherein the collimator is provided in a polygonal or circular shape that surrounds the outside of the scintillator and has a plurality of slots that can each pass an external radiation source through the scintillator.

6. A radiation monitoring device characterized in that in the first paragraph, the analysis unit additionally comprises a nuclide determination unit that determines the nuclide by using at least one of the peak position, count density, and area value of the data received from the measurement unit. 7.1) A method for monitoring radiation, comprising: a step of irradiating a gamma ray into a scintillator through each slot of a collimator having slots facing different directions; 2) a step of classifying a signal measured through a first light sensor and a second light sensor provided at both ends of the scintillator into a preset range section according to a difference in the amount of light collected by the first light sensor and the second light sensor; 3) a step of determining a response height of the scintillator for each classified range section; 4) a step of forming an energy spectrum for each determined response height; and 5) a step of outputting direction information of a radiation source according to the formed energy spectrum.

8. A radiation monitoring method according to claim 7, wherein the first and second light sensors are any one of a photomultiplier tube (PMT), a silicon photomultiplier (SiPM), a photodiode (PAD), and an avalanche photodiode (APD).

9. A radiation monitoring method according to claim 7, characterized in that the first and second light sensors are photomultiplier tubes (PMT).

10. A radiation monitoring device characterized in that, in the 7th paragraph, it further includes a step of determining a nuclide by using at least one of the peak position, coefficient density, and area value of the data in step 5).

11. A radiation monitoring method characterized in that it further includes a step of determining nuclide information using the energy spectrum information of step 4 in paragraph 7.

12. A radiation monitoring method comprising a step of analyzing a radiation incidence direction through a radiation monitoring device of the first clause equipped with a plurality of units; and a step of determining a point where two or more lines extending toward the analyzed radiation incidence direction meet as an area where a radioactive source exists.

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