Radioactive source identification system using compton image projection in three-dimensional virtual space

Abstract

A radiation source identification system using Compton image projection in a three-dimensional virtual space, according to the present invention, comprises: a gamma image generation module that includes a gamma camera and generates 4-pi full-solid-angle Compton image data; an indoor positioning module that includes a plurality of fixed beacons and one mobile beacon and generates coordinates of the mobile beacon; a rotating support module that includes a fixed plate on which the mobile beacon of the indoor positioning module and the gamma image generation module are mounted, and a driving control device that rotates the fixed plate according to an input directional angle; and an integrated data management module that stores and manages a three-dimensional building information model that depicts each facility of a nuclear facility as a three-dimensional object in a three-dimensional virtual space, converts the coordinates of the indoor positioning module and the directional angle of the rotating support module into reference coordinates and a reference direction in the three-dimensional virtual space, respectively, receives the Compton image data of the gamma image generation module, aligns same to the reference coordinates and the reference direction to project same, and identifies a radiation source.

Description

A radiation source identification system in a three-dimensional virtual space using Compton image projection

[0001] The present invention relates to a system for identifying a radiation source by projecting a Compton image in a three-dimensional virtual space model of a nuclear facility, and more specifically, to a system for identifying a radiation source object by projecting complete solid-angle Compton image data generated by a gamma camera or a gamma imaging device onto a three-dimensional nuclear facility model.

[0002] At nuclear power plants and nuclear-related facilities, radiation is measured and exposure management is implemented to ensure the radiation safety of workers and visitors. During operation, some equipment becomes radioactive or contaminated, becoming radioactive sources. In particular, during decommissioning, not only must radiation surveys be conducted in the anticipated workspace to manage radiation exposure for workers, but equipment that is a source of radiation among the equipment to be decommissioned requires special handling in accordance with radiation safety regulations. Therefore, identifying radioactive equipment is crucial. Recently, with the significant expansion of computer utilization, efforts are being made to build and utilize digital twin systems based on 3D nuclear power plant models to efficiently support the operation and decommissioning of nuclear power plants. Therefore, identifying radioactive source objects in the 3D power plant model and accurately inputting and linking their associated properties has become crucial for managing nuclear power plant operation and decommissioning projects.

[0003] Korean Patent No. 10-2374327, filed by the applicant, discloses a system for calculating the radiation intensity of nuclear power plant equipment elements using a 3D model and displaying a radiation map. This patent relates to a technology for managing a 3D model containing n source-term equipment elements in cyberspace, inputting dose rate measurements for at least n measurement point coordinates in cyberspace, and calculating the radiation intensity of the equipment elements by finding solutions to a set of equations that use the radiation intensity of the source-term equipment elements as unknowns, and displaying a radiation map based on the calculated radiation intensity. However, this patent does not disclose specific means for identifying which equipment or device is the radiation source in a 3D power plant model that simulates a situation where its shape changes during decommissioning or an unknown situation.

[0004] When calculating radiation intensity and radiation field using a 3D model, if a target object is omitted from the radiation source or an unnecessary radiation source is additionally set, the accuracy of the radiation intensity and radiation field calculation results may be significantly reduced.

[0005] The present invention provides a system for identifying a radiation source object in a three-dimensional virtual space model simulating a nuclear power facility or radiation-related facility using gamma imaging technology and indoor positioning technology.

[0006] A system for identifying a radiation source in a three-dimensional virtual space by Compton image projection according to the present invention comprises: a gamma camera, and a gamma image generation module for generating 4-pi full solid-angle Compton image data; an indoor positioning module for generating coordinates of a plurality of fixed beacons and one mobile beacon; a rotation support module having a fixed plate on which the mobile beacon of the indoor positioning module and the gamma image generation module are mounted, and a drive control device for rotating the fixed plate according to an input direction angle; and a data integration management module for storing and managing a three-dimensional building information model that depicts each facility of a nuclear facility as a three-dimensional object in a three-dimensional virtual space, and converting the coordinates of the indoor positioning module and the direction angle of the rotation support module into a reference coordinate and a reference direction in the three-dimensional virtual space, respectively, and receiving Compton image data of the gamma image generation module, aligning it with the reference coordinate and the reference direction, and projecting it to identify a matching radiation source.

[0007] Compton image data according to the present invention may be characterized in that it is generated separately for each nuclide.

[0008] Compton image data according to the present invention is expressed in a two-dimensional matrix structure corresponding to polar angle and azimuth angle, and can be characterized in that the values ​​of matrix elements generated for each nuclide are added for each element.

[0009] Compton image data according to the present invention is expressed as a two-dimensional matrix structure with a reference coordinate as the origin and corresponding polar angle and azimuth angle from the reference direction, and can be characterized in that when the value of the matrix element corresponding to the polar angle and azimuth angle of each object is equal to or greater than a set value, the object is automatically set as a radiation source.

[0010] The data integration management module according to the present invention may be characterized by correcting the coordinates of the mobile beacon of the indoor positioning module to indicate the coordinates of the center of the gamma camera.

[0011] The present invention has the effect of easily identifying radiation sources in all directions in a three-dimensional virtual space based on Compton data measured in real space, and enabling automatic setting of the radiation sources.

[0012] The present invention has the effect of improving the accuracy of calculation results when calculating the radiation intensity of a radiation source and calculating a radiation field by accurately identifying a radiation source.

[0013] In addition, the present invention provides an effect of being able to confirm radiation source arrangement information in real space through the Compton projection result in a three-dimensional virtual space.

[0014] Figure 1 is a block diagram of a three-dimensional virtual space radiation source identification system according to the present invention.

[0015] Figure 2 is an example of a superimposed gamma image generated by a conventional gamma camera.

[0016] Figure 3 is an example diagram visualizing the two-dimensional matrix structure of the complete solid angle Compton image data of 4-pi in a two-dimensional grid format.

[0017] Figure 4 is a reference diagram to explain the relationship between gamma camera orientation and polar coordinate system.

[0018] Figure 5 is an exemplary diagram showing a state in which Compton image data is projected onto a three-dimensional virtual space of a BIM model according to the present invention.

[0019] Below, specific embodiments of the present invention are described. However, the present invention can be implemented in various forms and is not limited to the embodiments described herein. The drawings attached to the present invention have been simplified for convenience of explanation, and some parts have been exaggerated or irrelevant to the description have been omitted to clearly explain the present invention.

[0020] The three-dimensional virtual space radiation source identification system (10) according to the present invention is configured to include a gamma image generation module (110), an indoor positioning module (120), a rotation support module (130), and a data integration management module (100), as schematically illustrated in FIG. 1.

[0021] In the present invention, a module refers to a functional unit of software for performing a specific function, or a functional unit combining hardware and software for operating the same. A module may exist as a separate physical unit or may be distributed across multiple physical units.

[0022] The gamma image generation module (110) includes a gamma camera. The gamma camera is also referred to as a Compton camera or a gamma imaging device. A typical gamma camera is a device that helps visually recognize the location of a gamma radiation source in a field by superimposing a Compton image of gamma rays incident from the front onto an optical image through an optical lens. Fig. 2 shows an example of a superimposed gamma image generated by a typical gamma camera function. The superimposed gamma image of a typical gamma camera typically covers a solid angle of 2π in front. The gamma image indicates a part with a high radiation intensity in the color order of, for example, red-yellow-green-blue, and the colored part indicates the direction of the location of the radiation source.

[0023] Compton images are generated according to the principles described in papers such as “Development and Applications of Compton Camera-A Review”, Sensors, 2022, vol. 22, 7374. The gamma camera has two detector layers, and when a gamma-ray photon is incident, the front detector becomes a scatterer detector and the rear detector acts as an absorber detector, and the scattering angle is calculated according to the scattering relationship to determine the incident direction of the gamma ray.

[0024] The gamma image generation module (110) of the present invention has a feature of generating 4π full solid angle Compton image data. As described above, since the gamma camera has two detector layers, in the case of gamma rays incident from the rear, the scattering detector and the absorption detector switch roles, so that the direction of the gamma ray source incident from the rear as well as the front can be determined, and thus 4π full solid angle Compton image data can be generated. That is, if the detector layer where the photon is first incident is the front, a signal in the 2π solid angle direction of the front is recorded, and if the photon is first incident on the rear detector layer, a signal in the 2π solid angle direction of the rear is recorded, so that 4π full solid angle Compton image data is generated overall. In other words, in the present invention, the 4-pi complete solid angle Compton image data means data expressed in a two-dimensional matrix format by aggregating the counting of gamma rays incident at the origin in a coordinate system with the center position of the gamma camera as the origin for all solid angle directions.

[0025] Figure 3 is an example of a 4π full solid angle Compton image data recorded in a 180x180 two-dimensional matrix structure corresponding to the polar angle (θ) and azimuthal angle (φ) and visualized as a data pattern in a two-dimensional grid format. Through Figure 3, it can be understood that when the gamma camera is oriented in the z-direction in the coordinate system of Figure 4, gamma rays incident from all directions of the polar angle (θ) and azimuthal angle (φ) can be counted and expressed in a two-dimensional matrix structure.

[0026] The indoor positioning module (120) comprises three or more stationary beacons and one mobile beacon, and is composed of an indoor navigation system that generates coordinates of the mobile beacons. In some cases, the stationary beacons are referred to as anchors, and the mobile beacons are referred to as tags. Since radiation work is mainly performed indoors, an indoor positioning system that is capable of operating in a GPS-denied environment is used. The coordinates of the mobile beacons are calculated by trilateration by measuring the signal arrival time to the stationary beacon whose location is known. The signal may be an ultrasonic signal or an ultra-wide band (UWB) signal. A modem is used to convert analog signals into digital signals.

[0027] The rotation support module (130) includes a fixed plate for mounting and fixing the movable beacon of the indoor positioning module (120) and the gamma image generation module (110), and a driving control device for rotating the fixed plate according to the input directional angle received. The rotation can be performed by a pan-tilt operation in the azimuth and polar angle directions, but it is preferable to pan only in the azimuth direction in a horizontal state for the convenience of the directional angle conversion to be performed subsequently. The directional angle of the rotation support module (130) is fixed so that the state in which the pan-tilt angle is zero is in the zero direction, and the center line of the gamma camera of the gamma image generation module (110) is aligned with the zero direction.

[0028] It is preferable that the mobile beacon be attached directly above the gamma camera so that the coordinates of the mobile beacon correspond to the coordinates of the gamma camera. However, if there is a difference in distance between the position of the mobile beacon and the center of the gamma camera that requires correction, a method may be adopted to correct the coordinates of the mobile beacon so that they indicate the center of the gamma camera. This method corrects the coordinates of the mobile beacon generated by the indoor positioning module (120) in the data integration management module (100) to be described later so that they indicate the coordinates of the center of the gamma camera.

[0029] The data integration management module (100) stores and manages a 3D building information model (3D-BIM) that depicts each facility of a nuclear power facility as a 3D object in a 3D virtual space.

[0030] A 3D Building Information Model (BIM) is a 3D model that depicts each facility of a nuclear facility as a 3D object, including geometric information and material property information. This serves as the basis for calculating the object's radiation intensity property information. The 3D object models included here specifically represent 3D elements that model equipment or structures, including pumps, valves, pipes, heat exchangers, tanks, and walls. SOLIDWORKS or other commercial 3D modeling tools can be used for the initial creation of the 3D model, and the object model file formats can typically be various formats such as stl, ifc, and obj. 3D BIM defines a virtual space using a 3-axis frame to correspond to the real space, and the location in the virtual space can be expressed as coordinates (x, y, z).

[0031] In addition, the data integration management module (100) converts the coordinates of the mobile beacon of the indoor positioning module (120) and the directional angle of the rotation support module (130) into reference coordinates and reference direction in a three-dimensional virtual space, respectively, and receives the Compton image data of the gamma image generation module (110), aligns it to the reference coordinates and reference direction, projects it into the three-dimensional virtual space, and identifies a matching object as a radiation source. Data communication between each module can use a short-range wireless communication technology such as Wi-Fi, Bluetooth, or ZigBee, and in case of close proximity, USB communication can be utilized for convenience.

[0032] The coordinates of the mobile beacon of the indoor positioning module (120) are first determined as the local coordinates of the indoor positioning system and converted into the reference coordinates of the mobile beacon in the 3D virtual space of the BIM with reference to the coordinates of the fixed beacon installation location in the 3D virtual space. The orientation angle of the rotation support module (130) means the orientation angle when rotated from the zero direction. The zero direction of the rotation support module (130) is positioned in the direction of a base in the 3D virtual space, and the orientation angle of the rotation support module (130) is converted into a reference direction in the 3D virtual space of the BIM with reference to the direction of the base. Therefore, the reference coordinates and the reference direction represent the coordinates and direction of the gamma camera in the 3D virtual space. If necessary, a plurality of reference coordinates and reference directions can be set and the Compton image data acquired respectively can be projected to confirm the identification result repeatedly.

[0033] Fig. 5 is an example diagram showing the 4-pi full solid angle Compton image data illustrated in Fig. 3 aligned to the reference coordinates and reference direction, projected onto the 3D virtual space of the BIM model, and an image captured from the same camera direction as the overlaid gamma image of Fig. 2. Comparing Fig. 5 with Fig. 2, it can be confirmed that the spatial interrelationships of the Compton images and devices in the virtual space and the real space are substantially identical. If there is a radiation source at the rear, it is of course possible to confirm the location of the radiation source at the rear by changing the camera direction on the BIM in the opposite direction using the 4-pi full solid angle Compton image data.

[0034] In this way, once the identification of radiation sources in all solid angle directions on the BIM is completed, the method disclosed in the “System for calculating radiation intensity and displaying radiation map of nuclear power plant equipment elements using a 3D model” of Patent No. 10-2374327, which is described in the background technology of the invention, can be used to calculate the radiation intensity and radiation field of the identified radiation source.

[0035] Compton image data, as illustrated in Fig. 3, has a two-dimensional matrix structure with the reference coordinate as the origin and the polar angle (θ) and azimuth angle (φ) corresponding to the reference direction, and when the data value of the matrix element corresponding to the polar angle and azimuth angle of each object is greater than or equal to a setting value, the object corresponding to the polar angle and azimuth angle in the three-dimensional virtual space of BIM can be automatically set as a radiation source. Since the data value of the matrix element cumulatively changes according to the gamma-ray measurement time, the setting value can be given as a value for a set measurement time or as a relative value for the average of the entire stereoscopic angle. Of course, it is also possible to manually set a radiation source by clicking the corresponding object to which the Compton image matches on the BIM.

[0036] The above Compton image data can be generated separately for each nuclide and projected separately for each nuclide in a three-dimensional virtual space. This is possible because the detector of the gamma image generation module (110) counts the gamma ray characteristic energy of the incident nuclide for each energy channel, and can be applied when identification of the radiation source of a specific nuclide is required.

[0037] The above Compton image data is expressed in a two-dimensional matrix structure corresponding to the polar angle and azimuth angle, and Compton image data generated for each nuclide can be added for each matrix element to generate one Compton image data, which can be applied when all radiation sources are to be identified regardless of the nuclide.

[0038] The present invention has the effect of easily identifying radiation sources in all directions in a three-dimensional virtual space based on data measured in real space, and enabling automatic setting of the radiation sources.

[0039] In 3D BIM, if a target object is omitted from a radiation source or an unnecessary radiation source is added, the accuracy of the calculation results may be significantly reduced when calculating the radiation intensity and radiation field of the radiation source based on this assumption. Therefore, the present invention has the effect of improving the accuracy of calculating the radiation intensity and radiation field of the radiation source by accurately identifying the radiation source.

[0040] In addition, the present invention has the effect of being able to confirm radiation source arrangement information in real space through the Compton projection result in a three-dimensional virtual space.

[0041] The invention disclosed above is capable of various modifications without detracting from the fundamental concept. Therefore, the above embodiments should be interpreted as illustrative and not limiting. Substitution of equivalents in the appended claims is within the scope of the appended claims.

[0042]

[0043] The present invention relates to a system for identifying a radiation source by Compton image projection in a three-dimensional virtual space model of a nuclear power facility, and can contribute to improving radiation work safety in a nuclear power plant by identifying a radiation source object in a three-dimensional power plant model, and thus has industrial applicability in related fields.

Claims

1. A gamma image generation module including a gamma camera and generating 4-pi full solid angle Compton image data expressed in a two-dimensional matrix structure corresponding to polar angle and azimuth angle; An indoor positioning module comprising a plurality of fixed beacons and one mobile beacon, and generating coordinates of the mobile beacon; A rotating support module including a fixed plate mounting the movable beacon of the indoor positioning module and the gamma image generation module and a driving control device that rotates the fixed plate according to the input direction angle; and A system for identifying a radiation source in a 3D virtual space by Compton image projection, characterized in that it comprises a data integration management module for storing and managing a 3D building information model that depicts each facility of a nuclear power facility as a 3D object in a 3D virtual space, converting the coordinates of the indoor positioning module and the directional angle of the rotation support module into reference coordinates and reference direction in the 3D virtual space, respectively, receiving Compton image data of the gamma image generation module and aligning it to the reference coordinates and reference direction, and using the reference coordinates as an origin, and automatically setting an object corresponding to the polar angle and azimuth angle in the 3D virtual space as a radiation source when the value of the matrix element corresponding to the polar angle and azimuth angle of each object from the reference direction is greater than a set value; 2. In paragraph 1, A three-dimensional virtual space radiation source identification system using Compton image projection, characterized in that the above Compton image data is generated separately for each nuclide.

3. In paragraph 1, A three-dimensional virtual space radiation source identification system using Compton image projection, characterized in that the data integration management module corrects the coordinates of the mobile beacon of the indoor positioning module to indicate the coordinates of the center of the gamma camera.

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