WO2020252815A1 - 核燃料颗粒包覆层厚度检测方法及装置 - Google Patents

核燃料颗粒包覆层厚度检测方法及装置 Download PDF

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Publication number
WO2020252815A1
WO2020252815A1 PCT/CN2019/094207 CN2019094207W WO2020252815A1 WO 2020252815 A1 WO2020252815 A1 WO 2020252815A1 CN 2019094207 W CN2019094207 W CN 2019094207W WO 2020252815 A1 WO2020252815 A1 WO 2020252815A1
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WIPO (PCT)
Prior art keywords
coating layer
thickness
magnification
nuclear fuel
sample
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PCT/CN2019/094207
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English (en)
French (fr)
Inventor
刘坚
姜潮
熊岩
张航
胡钊川
李蓉
陈宁
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湖南大学
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Application filed by 湖南大学 filed Critical 湖南大学
Priority to US17/779,175 priority Critical patent/US11728056B2/en
Publication of WO2020252815A1 publication Critical patent/WO2020252815A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B15/00—Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons
    • G01B15/02—Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons for measuring thickness
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G21C17/06—Devices or arrangements for monitoring or testing fuel or fuel elements outside the reactor core, e.g. for burn-up, for contamination
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/42—Selection of substances for use as reactor fuel
    • G21C3/58—Solid reactor fuel Pellets made of fissile material
    • G21C3/62—Ceramic fuel
    • G21C3/623—Oxide fuels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
    • G01B11/0625—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating with measurement of absorption or reflection
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/42—Selection of substances for use as reactor fuel
    • G21C3/58—Solid reactor fuel Pellets made of fissile material
    • G21C3/62—Ceramic fuel
    • G21C3/626—Coated fuel particles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the invention relates to the technical field of measurement and detection, in particular to a method and device for detecting the thickness of a nuclear fuel particle coating layer.
  • the nuclear fuel particle is the smallest unit in the fuel sphere of the high-temperature gas-cooled reactor. It consists of a UO2 core and a coating layer on the outside.
  • the coating layer is composed of four layers of pyrolytic carbon and silicon carbide with different thicknesses and densities.
  • the diameter of nuclear fuel particles is less than 1mm, among which the diameter of UO2 core is less than 0.5mm, and the thickness of each layer of the coating layer is only 20-140 ⁇ m.
  • the size of the UO2 core and the thickness of each coating layer directly affect the efficiency and safety of reactor operation. Therefore, it is very important to accurately measure the thickness of each coating layer of each batch of nuclear fuel particles.
  • the methods used to detect the thickness of the coating layer of nuclear fuel particles mainly include X-ray microscopic imaging, V-groove, metallographic, and particle size analyzer methods.
  • the metallographic method is most suitable for industrial applications.
  • the metallographic method usually uses resin to coat nuclear fuel particles, and the nuclear fuel particles are exposed to the core and various coating layers through grinding processing to make grinding samples. Manually observe the surface of the sample through a microscope, select complete nuclear fuel particles with good grinding conditions, and then manually mark the three-point fitting circle on the boundary of each coating layer as the boundary of each layer, and make a ray through the center of the circle. The distance of each boundary intersection is taken as the thickness of each layer.
  • This detection method is mainly carried out manually, with poor automation and low measurement accuracy.
  • nuclear radiation may endanger the health of inspection workers.
  • the present invention provides a method and device for detecting the thickness of the coating layer of nuclear fuel particles, in an effort to solve or at least alleviate the above problems.
  • a method for detecting the thickness of a nuclear fuel particle coating layer includes: acquiring a surface image of a sample to be tested under a first magnification, the surface of the sample to be tested includes a plurality of nuclear fuel particles Determine the measurable particles in the surface image, wherein the measurable particles are nuclear fuel particles with a cross-sectional area greater than a first threshold and an average distance from surrounding particles less than a second threshold; at the second magnification, Collect a cross-sectional image of a measurable particle, wherein the second magnification is greater than the first magnification; determine the center of the measurable particle and the contour line of each coating layer in the cross-sectional image, according to the center and each coating The contour line of the layer determines the thickness of each cladding layer.
  • the method for detecting the thickness of the coating layer of nuclear fuel particles before the step of acquiring the first surface image of the sample to be tested, it further includes: at a third magnification, collecting An edge image, wherein the third magnification is less than the first magnification; the center position of the sample to be tested is determined according to the edge image, and the center of the sample to be tested is moved to the center of the field of view of the microscope.
  • the step of collecting the surface image of the sample to be tested at the first magnification includes: dividing the surface of the sample to be tested into For multiple regions, under the first magnification, the surface images of each region are sequentially collected in a preset order.
  • the surface of the sample to be tested is divided into a plurality of regions of equal size, and at the first magnification, starting from the central region, in order
  • the surface image of each area is acquired in sequence in clockwise or counterclockwise order.
  • the step of determining the thickness of each coating layer according to the center and the contour line of each coating layer includes: At least one ray is emitted, and the ray intersects each contour line at each point; the average value of the intersection distance corresponding to the coating layer is taken as the thickness of the coating layer, where the intersection distance is the diplomatic point and the inner The distance of the intersection, the civil point is the intersection of the ray and the outer contour of the coating layer, and the inner intersection is the intersection of the ray and the inner contour of the coating.
  • two mutually perpendicular straight lines are drawn across the center, and the straight lines respectively intersect the contour lines at each point; and the coating layer corresponds to The average value of the intersecting point distance is the thickness of the coating layer.
  • the method further includes: determining Whether the thickness of the coating layer is abnormal; when the thickness of the coating layer is abnormal, the measurable particles shall be rechecked.
  • the step of re-inspecting the measurable particles includes: acquiring a partial cross-sectional image of the measurable particles at a fourth magnification, wherein , The fourth magnification is greater than the second magnification; the center of the measurable particle and the contour line of each coating layer in the partial cross-sectional image are determined, and a ray is emitted from the center, and the ray is respectively and Each contour line intersects at each point; the intersection distance corresponding to the coating layer is taken as the thickness of the coating layer.
  • the abnormality includes: the absolute value of the difference between the thickness of a coating layer of a measurable particle and the thickness of the same coating layer of other measurable particles. The value is greater than the third threshold.
  • the method further includes: storing the images collected in the detection process and the related measured data in a database.
  • a nuclear fuel particle coating thickness detection device comprising: a microscope, an industrial camera, and a computing device, the industrial camera is respectively connected to the microscope and the computing device;
  • the microscope It includes an electric control stage and an electric control converter, the electric control stage is used to carry the sample to be tested, the electric control converter is provided with a plurality of objective lenses with different magnifications;
  • the electric control carrier The object stage and the electronic control converter are respectively connected to the computing device, and the computing device is adapted to control the positions of the electronic control stage and the electronic control converter according to program instructions, thereby adjusting the position of the sample to be tested And switching the objective lens;
  • the industrial camera is adapted to collect an image of the sample to be tested, and send the image to the computing device, so that the computing device can determine the coating thickness of nuclear fuel particles based on the image.
  • the computing device includes: at least one processor and a memory storing program instructions; when the program instructions are read and executed by the processor , So that the nuclear fuel particle coating thickness detection device executes the coating thickness detection method described above.
  • the nuclear fuel particle coating thickness detection scheme of the present invention can automatically collect the surface image of the sample to be tested under the first magnification, and select the measurable particles that meet the measurement requirements from it; subsequently, at a higher magnification (ie, the second Under magnification), the cross-sectional image of the measurable particles is collected, and the center of the measurable particle and the contour line of each coating layer are extracted from it, and the thickness of each coating layer is determined according to the center and the contour line.
  • the nuclear fuel particle coating thickness detection scheme of the present invention realizes the automatic detection of the thickness of each coating layer. Compared with the prior art, the degree of automation, measurement efficiency, and measurement accuracy are greatly improved, and can provide more for nuclear reactor components. Accurate measurement data, and avoid the detection of workers from radiation damage.
  • Fig. 1 shows a schematic diagram of a nuclear fuel particle coating thickness detection device 100 according to an embodiment of the present invention
  • FIG. 2 shows a schematic diagram of a computing device 130 according to an embodiment of the present invention
  • FIG. 3 shows a flowchart of a method 300 for detecting the thickness of a coating layer of nuclear fuel particles according to an embodiment of the present invention
  • FIG. 4 shows a schematic diagram of a surface image of a sample to be tested collected at a first magnification according to an embodiment of the present invention
  • Fig. 5 shows a schematic diagram of the distance between two nuclear fuel particles according to an embodiment of the present invention
  • Fig. 6 shows a schematic diagram of a cross-sectional image of a measurable particle collected at a second magnification according to an embodiment of the present invention
  • FIG. 7 shows a flowchart of a method 700 for detecting the thickness of a coating layer of nuclear fuel particles according to another embodiment of the present invention
  • Fig. 8 shows a schematic diagram of an edge image of a sample to be tested collected at a third magnification according to an embodiment of the present invention
  • FIG. 9 shows a schematic diagram of the surface area division of a sample to be tested according to an embodiment of the present invention.
  • Fig. 10 shows a schematic diagram of a partial cross-sectional image of a measurable particle collected at a fourth magnification according to an embodiment of the present invention.
  • FIG. 1 shows a schematic diagram of an apparatus 100 for detecting the thickness of a coating layer of nuclear fuel particles according to an embodiment of the present invention.
  • the apparatus 100 can realize automatic detection of the thickness of each coating layer of nuclear fuel particles.
  • the apparatus 100 includes a microscope 110, an industrial camera 120, and a computing device 130 (the computing device 130 is not shown in FIG. 1).
  • the microscope 110 may be of any model, and the present invention does not limit the manufacturer and model of the microscope 110. As shown in FIG. 1, in the embodiment of the present invention, the microscope 110 includes an electronic control converter 111 and an electronic control stage 112.
  • the electronic control converter 111 is provided with a plurality of objective lenses 114 with different magnifications. By rotating the electronic control converter 111, the objective lens 114 can be switched, thereby adjusting the magnification of the microscope 110.
  • the present invention does not limit the number and magnification of the objective lens 114.
  • the microscope 110 includes four objective lenses 114 with magnifications of 2X, 5X, 10X, and 40X, respectively.
  • the electronically controlled stage 112 is used to carry the sample 200 to be tested. By adjusting the position of the electronically controlled stage 112 on the XYZ axis in space, the objective lens 114 and the industrial camera 120 can be automatically focused and the sample 200 to be tested can be adjusted in the microscope field of view. s position. It should be noted that the present invention does not limit the travel range of the electronically controlled stage 112 on the XYZ axis. According to an embodiment, the electronically controlled stage 112 has a stroke of 50 mm or more in the XY axis direction, and a stroke of 10 mm or more in the Z axis direction.
  • the sample 200 to be tested includes a plurality of nuclear fuel particles, and its surface includes a cross section of the plurality of nuclear fuel particles.
  • the embodiment of the present invention can detect the thickness of each coating layer of nuclear fuel particles by collecting images of the surface of the sample 200 to be tested under different magnifications, and analyzing and processing the collected images.
  • the sample 200 to be tested can be made by, for example, mounting and grinding processes, that is, first, the nuclear fuel particles are poured into the mounting mold to make the nuclear fuel particles closely arranged. Subsequently, the curing agent is poured into the mounting mold, and the nuclear fuel particles are fixed and wrapped in the curing agent by the inlay process to form a solid sample consistent with the shape of the mold.
  • the curing agent may be a material such as resin, but is not limited thereto.
  • the surface of the solid sample is ground, so that the nuclear fuel particles are exposed to the core and each coating layer (that is, the cross-section of the nuclear fuel particles is shown), and the sample 200 to be tested is made.
  • the sample 200 to be tested can be of any shape and size. Specifically, the shape and size of the sample 200 to be tested depends on the shape and size of the mounting mold and the amount of sample material removed during the grinding process. The present invention does not limit the shape and size of the sample 200 to be tested.
  • the following (the embodiments of FIGS. 4-6 and 8-10) will take the sample 200 to be tested as a cylindrical sample with a certain height as an example to illustrate the coating thickness detection scheme of the present invention.
  • the nuclear fuel particles included in the sample 200 to be tested can be of any structure and any material.
  • the present invention does not limit the type of nuclear fuel particles, the number of coating layers, thickness, materials, etc. .
  • the following (the embodiments of FIGS. 4-6 and 8-10) will take nuclear fuel particles with four coating layers as an example to illustrate the coating thickness detection scheme of the present invention.
  • the industrial camera 120 may be of any model, and the present invention does not limit the manufacturer and model of the industrial camera 120.
  • the industrial camera 120 may have a 1-inch sensor chip, 12 million real physical pixels, a resolution of 4000*3000, a C-type camera interface, and a frame rate of 15 frames per second.
  • the industrial camera 120 is connected to the microscope 110 and the computing device 130 respectively.
  • the industrial camera 120 is connected to the microscope 110 through a camera interface 122, and is connected to the computing device 130 through a data cable such as USB.
  • the industrial camera 120 is used to collect an image of the sample to be tested magnified by the microscope 110, and send the image to the computing device 130 for image processing to detect the thickness of each coating layer of nuclear fuel particles.
  • the computing device 130 can be any device with storage and computing capabilities.
  • it can be a personally configured computer such as a desktop computer, a notebook computer, or a computer with a higher hardware configuration such as a workstation or a server, or a mobile phone or a tablet computer. , Smart wearable devices and other mobile terminals, but not limited to this.
  • the industrial camera 120, the electronic control converter 111, and the electronic control stage 112 are respectively connected to the computing device 130.
  • the computing device 130 can control the positions of the electronically controlled converter 111 and the electronically controlled stage 112 according to program instructions, thereby switching the objective lens 114 and adjusting the position of the sample 200 to be tested.
  • the industrial camera 120 is adapted to collect images of samples to be tested under different magnifications, and send the images to the computing device 130.
  • the computing device 130 analyzes and processes the image based on preset program instructions, and determines the nuclear fuel particle's Coating thickness.
  • FIG. 2 shows a schematic diagram of a computing device 130 according to an embodiment of the present invention.
  • the computing device 130 shown in FIG. 2 is only an example.
  • the computing device used to implement the method for detecting the thickness of the coating layer of nuclear fuel particles of the present invention may be any type of device, and its hardware configuration It can be the same as the computing device 130 shown in FIG. 2 or different.
  • the computing device used to implement the method for detecting the thickness of the coating layer of nuclear fuel particles of the present invention can add or delete the hardware components of the computing device 130 shown in FIG. 2, and the present invention does not make any specific hardware configuration of the computing device. limit.
  • the computing device 130 typically includes a system memory 106 and one or more processors 104.
  • the memory bus 108 may be used for communication between the processor 104 and the system memory 106.
  • the processor 104 can be any type of processing, including but not limited to: microprocessor ( ⁇ P), microcontroller ( ⁇ C), digital information processor (DSP), or any combination thereof.
  • the processor 104 may include one or more levels of cache, such as the first level cache 110 and the second level cache 112, the processor core 114, and the registers 116.
  • the exemplary processor core 114 may include an arithmetic logic unit (ALU), a floating point number unit (FPU), a digital signal processing core (DSP core), or any combination thereof.
  • ALU arithmetic logic unit
  • FPU floating point number unit
  • DSP core digital signal processing core
  • the example memory controller 118 may be used with the processor 104, or in some implementations, the memory controller 118 may be an internal part of the processor 104.
  • the system memory 106 may be any type of memory, including but not limited to: volatile memory (such as RAM), non-volatile memory (such as ROM, flash memory, etc.), or any combination thereof.
  • the system memory 106 may include an operating system 120, one or more programs 122, and program data 124.
  • the program 122 may be arranged to be executed by one or more processors 104 using program data 124 on an operating system.
  • the computing device 130 may also include an interface bus 140 that facilitates communication from various interface devices (eg, output device 142, peripheral interface 144, and communication device 146) to the basic configuration 102 via the bus/interface controller 131.
  • the example output device 142 includes a graphics processing unit 148 and an audio processing unit 150. They can be configured to facilitate communication with various external devices such as displays or speakers via one or more A/V ports 152.
  • the example peripheral interface 144 may include a serial interface controller 154 and a parallel interface controller 156, which may be configured to facilitate communication via one or more I/O ports 158 and input devices such as keyboards, mice, pens, etc. , Voice input devices, touch input devices) or other peripherals (such as printers, scanners, etc.) to communicate.
  • the example communication device 146 may include a network controller 160, which may be arranged to facilitate communication with one or more other computing devices 162 via a network communication link via one or more communication ports 164.
  • a network communication link may be an example of a communication medium.
  • the communication medium may generally be embodied as computer readable instructions, data structures, and program modules in a modulated data signal such as a carrier wave or other transmission mechanism, and may include any information delivery medium.
  • a "modulated data signal" can be a signal in which one or more of its data sets or its changes can be carried out in a manner of encoding information in the signal.
  • communication media may include wired media such as a wired network or a dedicated line network, and various wireless media such as sound, radio frequency (RF), microwave, infrared (IR), or other wireless media.
  • RF radio frequency
  • IR infrared
  • the term computer readable media used herein may include both storage media and communication media.
  • the application 122 includes instructions for executing the nuclear fuel particle coating thickness detection method 300, which can instruct the aforementioned nuclear fuel particle coating thickness detection device 100 to perform the nuclear fuel particle coating of the present invention
  • Layer thickness detection method 300 by automatically switching the objective lens, automatically focusing, automatically adjusting the position of the sample to be tested, collecting images of the sample to be tested under different magnifications of the microscope, and analyzing and processing the images to determine the coating layers of nuclear fuel particles Thickness to realize automatic detection of coating thickness.
  • FIG. 3 shows a flowchart of a method 300 for detecting the thickness of a coating layer of nuclear fuel particles according to an embodiment of the present invention.
  • the method 300 is executed by the aforementioned nuclear fuel particle coating thickness detection device 100. As shown in FIG. 3, the method 300 starts at step S310.
  • step S310 at the first magnification, a surface image of the sample to be tested is collected, and the surface of the sample to be tested includes a plurality of sections of nuclear fuel particles.
  • the sample to be tested is a cylindrical sample made by mounting and grinding a plurality of nuclear fuel particles
  • the surface of the sample is a cylindrical sample made by mounting and grinding a plurality of nuclear fuel particles.
  • Layer that is, a cross-section showing multiple nuclear fuel particles.
  • the surface image collected at the first magnification should be able to show the cross-sections of multiple nuclear fuel particles.
  • the present invention does not limit the specific value of the first magnification.
  • Those skilled in the art can select an objective lens with a suitable magnification according to the actual size of the nuclear fuel particles, so that the surface image can display multiple nuclear fuel particle sections.
  • the diameter of nuclear fuel particles is about 1mm.
  • an objective lens with an imaging field of view diameter of about 4mm and a magnification of 5X ie, the first magnification of 5
  • the collected surface image of the sample to be tested will include multiple sections of nuclear fuel particles.
  • step S310 first, the sample to be tested is fixed on the electronically controlled stage 112 through a glass slide, a clamp, and other structures. Subsequently, according to the program instructions preset in the computing device 130, the electronically controlled converter 111 is automatically adjusted to switch the objective lens facing the stage to the objective lens with the first magnification. The position of the electronically controlled stage 112 is automatically adjusted, the sample to be tested is moved into the field of view of the objective lens, and autofocus is performed, so that the industrial camera 120 can present a clear image of the surface of the sample to be tested. Subsequently, the industrial camera 120 collects a surface image of the sample to be tested, and sends the collected surface image to the computing device 130 for analysis and processing.
  • step S320 the computing device 130 executes step S320.
  • step S320 the measurable particles in the surface image are determined, where the measurable particles are nuclear fuel particles with a cross-sectional area greater than a first threshold and an average distance from surrounding particles less than a second threshold.
  • the integrity of the nuclear fuel particles can be judged, that is, it can be judged whether the core and the coating layer peel off during the grinding process of the nuclear fuel particles.
  • the average distance between the nuclear fuel particles and the surrounding particles is less than the second threshold, it can be judged whether the grinding state of the nuclear fuel particles is good, and whether under grinding or over grinding occurs. In a good grinding state, the cross-section of the nuclear fuel particle should pass through the center of the nuclear fuel particle or be very close to the center of the sphere.
  • step S320 may be further implemented according to the following steps S322 to S326:
  • step S322 the center of each nuclear fuel particle in the surface image is determined, thereby determining the position of each nuclear fuel particle.
  • the surface image can be converted into a grayscale image and further converted into a binary image.
  • Perform morphological processing on the binary image (such as morphological opening operation, etc.) to eliminate isolated points, burrs, and fine adhesions between structures in the binary image, so that the binary image shows multiple separate and independent Of nuclear fuel particles.
  • a shape detection algorithm (such as the Hough transform algorithm, etc.) is used to identify the circular contour in the binary image and determine its center.
  • step S324 it is determined whether the cross-sectional area of the nuclear fuel particles is greater than the first threshold.
  • the center of each particle determined in step S322 may be taken as the center, and the image of each particle may be cropped with a cropping rectangle of equal size, and the cross-sectional area of the corresponding nuclear fuel particle may be determined according to the cropped image.
  • the size of the cropped rectangle can be determined according to the actual size of the nuclear fuel particles.
  • the size of the cropped rectangle can be set to be slightly larger than the circumscribed rectangle of the nuclear fuel particles.
  • the cross-section of the nuclear fuel particle is approximately a circle with a diameter of 1 mm, and its circumscribed rectangle is a square of 1 mm*1 mm. Accordingly, the cutting rectangle can be set to a square of 1.2 mm*1.2 mm.
  • the cut out image of a single nuclear fuel particle is binarized to obtain a binary image.
  • the particle appears as a bright area in the original surface image, as shown in Figure 4, the nuclear fuel particles in the solid rectangular boxes 1-7 are all complete particles. After binarizing the image of the complete nuclear fuel particle, the nuclear fuel particle will appear as a white circle in the binary image.
  • the part where the particles are peeled off appears as a dark area in the original surface image, as shown in Figure 4, the nuclear fuel particles in the dotted rectangular frame 8
  • the core and the three coating layers on the inner side are all peeled off during the grinding process.
  • the peeled-off part will appear as black in the binary image. Accordingly, the entire nuclear fuel particle will not appear as a white circle, but as a single A white ring, or completely black.
  • the number of pixels with a pixel value of 1 in the binary image is calculated, that is, the area of the white area in the binary image is calculated, and the calculation result is used as the cross-sectional area of the nuclear fuel particles.
  • the first threshold can be set by those skilled in the art with reference to the actual size of the nuclear fuel particles, and the present invention does not limit the value of the first threshold.
  • step S326 it is determined whether the average distance between the intact nuclear fuel particles and the surrounding particles is less than a second threshold.
  • the distance between two nuclear fuel particles is the minimum value of the distance from a point on the outermost contour of one particle to a point on the outermost contour of another particle.
  • the centers O1 and O2 of the two particles can be connected to obtain the line segment O1O2.
  • the line segment O1O2 intersects the outermost contours of the two particles at points A and B respectively.
  • the distance from point A to point B is the distance between the two particles.
  • the centers of the two nuclear fuel particles are O1 and O2 respectively, and the line segment O1O2 intersects the outermost contours of the two particles at points A and B respectively.
  • the coordinates of point A and point B in the image are (1128, 987) and (1133, 998) respectively. Calculate the distance from point A to point B based on the coordinates of the two, which is 12.08px.
  • the distance between the nuclear fuel particle and each surrounding particle is calculated separately to obtain multiple distances.
  • the average value of the plurality of intervals is calculated, that is, the average interval is calculated.
  • the second threshold can be set by those skilled in the art, and the present invention does not limit the value of the second threshold.
  • the present invention does not limit the unit of the second threshold, but the unit of the second threshold should be consistent with the unit of the average distance measured in step S320.
  • the unit of the average pitch is px (pixel)
  • the second threshold should also be px; after converting the pixel distance into a length distance according to the pixel equivalent, the unit of the average pitch is ⁇ m, nm and other length units, then the second The unit of the threshold value should also be a length unit such as ⁇ m and nm.
  • the measurable particles in the surface image can be determined.
  • the nuclear fuel particles in solid rectangular boxes 1-7 are measurable particles.
  • step S330 is executed.
  • step S330 a cross-sectional image of the measurable particle is collected at a second magnification, where the second magnification is greater than the first magnification.
  • the cross-sectional image collected at the second magnification should be able to clearly and completely show the cross-section of a measurable particle, and preferably, only the cross-section of a measurable particle can be shown.
  • the present invention does not limit the specific value of the second magnification.
  • Those skilled in the art can choose an objective lens with a suitable magnification according to the actual size of the nuclear fuel particles, so that the cross-sectional image can only show the complete section of a measurable particle .
  • the diameter of nuclear fuel particles is about 1mm.
  • an objective lens with an imaging field of view diameter of about 1.5mm and a magnification of 10X ie, a second magnification of 10
  • the industrial camera The collected cross-sectional image of a measurable particle will only contain a cross-section of a measurable particle.
  • step S330 according to the program instructions preset in the computing device 130, the electronically controlled converter 111 is automatically adjusted to switch the objective lens facing the stage to an objective lens with a second magnification. Subsequently, the position of the electronically controlled stage 112 is automatically adjusted, the measurable particles are moved into the field of view of the objective lens, and automatic focusing is performed, so that the industrial camera 120 can present a clear image of the measurable particles. Subsequently, the industrial camera 120 collects cross-sectional images of the measurable particles, and sends the collected images to the computing device 130 for analysis and processing.
  • step S340 the computing device 130 executes step S340.
  • step S340 the center of the measurable particle in the profile image and the contour line of each coating layer are determined, and the thickness of each coating layer is determined according to the center and the contour line of each coating layer.
  • the center of the measurable particle and the contour line of each coating layer can be determined by a shape detection algorithm.
  • the shape detection algorithm may be, for example, a Hough Transform (Hough Transform) algorithm, a Radon Transform (Radon Transform) algorithm, etc., but it is not limited thereto.
  • the thickness of each coating layer can be determined according to the following steps S342 and S344:
  • step S342 at least one ray is emitted from the center of the measurable particle, and each ray intersects each contour line at each point.
  • the present invention does not limit the number and direction of the rays made in step S342.
  • two mutually perpendicular straight lines can be made through the central point O, and the two straight lines respectively intersect the contour lines at A1 ⁇ E1, A1 ⁇ E2, A3 ⁇ E3, A4 ⁇ E4 Various points.
  • four rays are made across the center, and the angle between adjacent rays is 90°, and these four rays respectively intersect each contour line at each point.
  • step S344 the average value of the intersection distance corresponding to the coating layer is taken as the thickness of the coating layer, where the intersection distance is the distance between the diplomatic point and the inner intersection, and the civil point is the outer distance between the ray and the coating layer.
  • the intersection of the contour lines, the inner intersection is the intersection of the ray and the inner contour of the cladding layer.
  • the measurable particle includes four coating layers, from the inside to the outside, the coating layer a, the coating layer b, the coating layer c, and the coating layer d.
  • the intersections of the four rays with the inner contour of the cladding layer a are A1 to A4, and the intersections with the outer contour of the cladding a are B1 to B4, that is, the inner intersection of the cladding a is A1 to A4, government points are B1 ⁇ B4.
  • the cladding layer a corresponds to four intersection distances, which are B1-A1, B2-A2, B3-A3, and B4-A4, respectively.
  • the thickness of the coating layer a is the average of the four intersecting point distances, namely (B1-A1+B2-A2+B3-A3+B4-A4)/4.
  • the thickness of the coating layers b, c, d are (C1-B1+C2-B2+C3-B3+C4-B4)/4, (D1-C1+D2-C2+D3-C3+D4- C4)/4, (E1-D1+E2-D2+E3-D3+E4-D4)/4.
  • the radius of each contour line can be fitted, and the difference between the radius of the outer contour line and the radius of the inner contour line of a coating layer is taken as the thickness of the coating layer.
  • the radii of the five contour lines from the inside to the outside of the measurable particles are fitted to be R1 to R5, and the thicknesses of the coating layers a to d are R2-R1, R3-R2, respectively.
  • step S340 the thickness of each coating layer of the measurable particles can be measured.
  • the method 300 further includes the step of storing the images collected during the detection process and the related measured data in a database.
  • the collected images include the aforementioned surface image under the first magnification, the surface image marked with measurable particles, and the cross-sectional image under the second magnification, but are not limited thereto.
  • the relevant data includes, for example, the coating thickness data and center coordinates of each measurable particle, but is not limited thereto.
  • the present invention does not limit the specific data content stored in the database.
  • those skilled in the art can choose to store the cross-sectional image of the measurable particle and the measured thickness data of each coating layer in the database.
  • the statistical value of the coating thickness of a certain batch of nuclear fuel particles can be calculated, such as the maximum, minimum, average, variance, and standard deviation of each coating thickness. Not limited to this.
  • FIG. 7 shows a flowchart of a method 700 for detecting the thickness of the coating layer of nuclear fuel particles according to another embodiment of the present invention.
  • the method 700 is executed by the aforementioned nuclear fuel particle coating thickness detection device 100.
  • the nuclear fuel particles detected by the method 700 are more comprehensive and the detection process is more automated.
  • the method 700 starts at step S710.
  • step S710 an edge image of the sample to be tested is acquired under the third magnification.
  • the edge image collected at the third magnification should be able to show the arc edge of the sample to be tested.
  • the present invention does not limit the specific value of the third magnification.
  • Those skilled in the art can select an objective lens with a suitable magnification according to the actual size of the sample to be tested, so that the arc edge of the sample to be tested can be displayed in the edge image.
  • an objective lens with an imaging field diameter of about 8 mm and a magnification of 2X that is, a third magnification of 2 may be used.
  • step S710 first, the sample to be tested is fixed on the electronically controlled stage 112 through a glass slide, a clamp, and other structures. Subsequently, according to the program instructions preset in the computing device 130, the electronically controlled converter 111 is automatically adjusted to switch the objective lens facing the stage to an objective lens with a third magnification. The position of the electronically controlled stage 112 is automatically adjusted, the sample to be tested is moved into the field of view of the objective lens, and autofocus is performed, so that the industrial camera 120 can present a clear image of the surface of the sample to be tested. Subsequently, the industrial camera 120 collects the edge image of the sample to be tested, and sends the collected edge image to the computing device 130 for analysis and processing.
  • Fig. 8 shows an example of an edge image acquired at the third magnification.
  • step S720 the center position of the sample to be tested is determined according to the edge image, and the center of the sample to be tested is moved to the center of the field of view of the microscope.
  • the computing device 130 may use a contour extraction algorithm to extract the edge arc contour of the sample to be tested, use a circle to fit the edge of the sample, and determine the position and radius of the center (circle center).
  • a contour extraction algorithm to extract the edge arc contour of the sample to be tested, use a circle to fit the edge of the sample, and determine the position and radius of the center (circle center).
  • the center of the sample to be tested determined by circular fitting may be outside the pixel coordinate range of the edge image.
  • the position of the electronically controlled stage 112 is adjusted to move the center of the sample to be tested to the center of the field of view of the microscope.
  • step S730 the surface of the sample to be tested is divided into multiple regions, and the surface images of each region are sequentially collected in a preset order under the first magnification, where the first magnification is greater than the third magnification.
  • each area should include a plurality of sections of nuclear fuel particles.
  • the surface of the sample to be tested can be divided into multiple regions of equal size. Under 1 magnification, starting from the central region, the surface images of each region are sequentially collected in a clockwise or counterclockwise order. For example, as shown in Figure 9, the surface of the sample to be tested is divided into 52 rectangular areas, starting from the central area 1, and at the first magnification, the surface images of each area are sequentially collected in a counterclockwise direction. For each area, it is necessary to determine the measurable particles in the area and detect the thickness of each coating layer of the measurable particles according to the subsequent steps S740 to S780, so as to realize the comprehensive detection of the sample to be tested.
  • step S740 the measurable particles in the surface image are determined, where the measurable particles are nuclear fuel particles whose cross-sectional area is larger than the first threshold and the average distance from the surrounding particles is smaller than the second threshold.
  • step S750 a cross-sectional image of the measurable particles is collected at a second magnification, where the second magnification is greater than the first magnification.
  • step S760 the center of the measurable particle in the profile image and the contour line of each coating layer are determined, and the thickness of each coating layer is determined according to the center and the contour line of each coating layer.
  • Steps S740 to S760 are the same as the aforementioned steps S320 to S340.
  • steps S740 to S760 reference may be made to the related description of the foregoing steps S320 to S340, which will not be repeated here.
  • step S770 when the thickness of the coating layer is abnormal, the measurable particles are re-examined at a fourth magnification, where the fourth magnification is greater than the second magnification.
  • step S770 it is determined whether the thickness of the coating layer is abnormal, and when the thickness of the coating layer is abnormal, the corresponding measurable particles are rechecked.
  • the abnormal judgment standard can be set by those skilled in the art, and the present invention does not limit this.
  • the abnormality judgment criterion may be set as: the absolute value of the difference between the thickness of a coating layer of a measurable particle and the thickness of the same coating layer of other measurable particles is greater than the third threshold.
  • the measurable particle P includes four coating layers a to d, wherein the thickness of the coating layer a is tha; the average value of the thickness of the coating layer a of other measurable particles is tha, when it is greater than the third threshold, it is determined that the thickness data of the coating layer a of the measurable particle P is abnormal, and the measurable particle P needs to be rechecked.
  • the value of the third threshold can be set by those skilled in the art, which is not limited in the present invention.
  • the measurable particles can be rechecked according to the following steps:
  • Under the fourth magnification collect the local cross-sectional image of the measurable particles, where the fourth magnification is greater than the aforementioned second magnification; determine the center of the measurable particle and the contour line of each coating layer in the local cross-sectional image, from the center A ray is emitted, and the ray intersects each contour line at each point; the intersection distance corresponding to the coating layer is taken as the thickness of the coating layer.
  • the fourth magnification is greater than the aforementioned second magnification, and the partial cross-sectional image collected at the fourth magnification can only show the local edge of a single measurable particle.
  • the present invention does not limit the specific value of the fourth magnification.
  • Those skilled in the art can select an objective lens with a suitable magnification according to the actual size of the nuclear fuel particles, so that only the local edge of a measurable particle can be shown in the partial cross-sectional image.
  • the diameter of nuclear fuel particles is about 1mm.
  • an objective lens with an imaging field of view diameter of about 0.4mm and a magnification of 40X that is, a fourth magnification of 40
  • the industrial camera The collected partial cross-sectional image of a measurable particle only contains a local edge of a measurable particle.
  • FIG. 10 shows an example of a partial cross-sectional image acquired at the fourth magnification.
  • a contour extraction algorithm can be used to extract the arc edge contours of the edges of each coating layer of the measurable particles, and a circle can be used to fit the arc edge and determine its center (circle center) position.
  • the center of the measurable particle determined by circular fitting may be outside the pixel coordinate range of the local profile image.
  • a ray can be emitted from the center, and the ray intersects each contour line at each point; the intersection distance corresponding to the coating layer is taken as the thickness of the coating layer.
  • a ray emerges from the center (outside the image), and the ray intersects the contour lines at five points A to E.
  • the thicknesses of the coating layers a to d are B-A, C-B, D-C, and E-D, respectively.
  • the radius of each contour line can be fitted, and the difference between the radius of the outer contour line and the radius of the inner contour line of a coating layer is taken as the thickness of the coating layer.
  • the radii of the five contour lines from the inside to the outside of the measurable particles are fitted to be R1 to R5, and the thicknesses of the coating layers a to d are R2-R1, R3, respectively. -R2, R4-R3, R5-R4.
  • step S780 the images collected during the detection process and the related measured data are stored in the database; and the overall detection result is output according to the stored data.
  • the images collected during the detection process include: the edge image at the third magnification, the surface image of each area at the first magnification, the surface image of each area marked with measurable particles, and the profile image at the second magnification. , Partial cross-sectional images at the fourth magnification, etc., but not limited to this.
  • the relevant data includes, for example, the coating thickness data and center coordinates of each measurable particle, but is not limited thereto.
  • Those skilled in the art can choose to store part or all of the images and related data involved in the detection process according to actual needs.
  • the present invention does not limit the specific data content stored in the database.
  • those skilled in the art can choose to store the cross-sectional image of the measurable particle and the measured thickness data of each coating layer in the database.
  • step S780 is the last step of method 700 in the embodiment shown in FIG. 7, those skilled in the art will understand that the data storage process usually runs through the entire thickness detection process, that is, in steps S710 ⁇ During the execution of S770, whenever an image or related data that needs to be stored is generated, it is immediately stored in the database, without waiting for all steps to be executed before storing the related data.
  • the test result data includes, for example: the number of fuel particles on the sample to be tested, the proportion of measurable particles, the thickness of each coating layer of a single fuel particle, the average thickness of each coating layer of fuel particles, the distribution of coating layer thickness, and coating The range of layer thickness deviation, and the corresponding judgment data output based on the measurement result (for example, whether a certain batch of nuclear fuel particles meets the requirements, etc.), but not limited to this.
  • the nuclear fuel particle coating thickness detection scheme of the present invention realizes the automatic detection of the thickness of each coating layer. Compared with the prior art, the degree of automation, measurement efficiency, and measurement accuracy are greatly improved, and can provide more for nuclear reactor components. Accurate measurement data, and avoid the detection of workers from radiation damage.
  • the various technologies described here can be implemented in combination with hardware or software, or a combination of them. Therefore, the method and device of the present invention, or some aspects or parts of the method and device of the present invention may be embedded in a tangible medium, such as a removable hard disk, U disk, floppy disk, CD-ROM, or any other machine-readable storage medium
  • program code ie, instructions
  • the machine becomes a device for practicing the present invention.
  • the computing device When the program code is executed on a programmable computer, the computing device generally includes a processor, a storage medium readable by the processor (including volatile and nonvolatile memory and/or storage elements), and at least one input device, And at least one output device.
  • the memory is configured to store program codes; the processor is configured to execute the nuclear fuel particle coating thickness detection method of the present invention according to instructions in the program codes stored in the memory.
  • readable media include readable storage media and communication media.
  • the readable storage medium stores information such as computer readable instructions, data structures, program modules, or other data.
  • Communication media generally embody computer readable instructions, data structures, program modules or other data in modulated data signals such as carrier waves or other transmission mechanisms, and include any information delivery media. Combinations of any of the above are also included in the scope of readable media.
  • the algorithms and displays are not inherently related to any particular computer, virtual system or other equipment.
  • Various general-purpose systems can also be used with the examples of the present invention. From the above description, the structure required to construct this type of system is obvious.
  • the present invention is not directed to any specific programming language. It should be understood that various programming languages can be used to implement the content of the present invention described herein, and the above description of a specific language is to disclose the best embodiment of the present invention.
  • modules or units or components of the device in the example disclosed herein can be arranged in the device as described in this embodiment, or alternatively can be positioned differently from the device in this example In one or more devices.
  • the modules in the foregoing examples can be combined into one module or further divided into multiple sub-modules.
  • modules or units or components in the embodiments can be combined into one module or unit or component, and in addition, they can be divided into multiple sub-modules or sub-units or sub-components. Except that at least some of such features and/or processes or units are mutually exclusive, any combination can be used to compare all features disclosed in this specification (including the accompanying claims, abstract and drawings) and any method or methods disclosed in this manner or All the processes or units of the equipment are combined. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract and drawings) may be replaced by an alternative feature providing the same, equivalent or similar purpose.
  • some of the embodiments are described herein as methods or combinations of method elements that can be implemented by a processor of a computer system or by other devices that perform the described functions. Therefore, a processor with the necessary instructions for implementing the method or method element forms a device for implementing the method or method element.
  • the elements described herein of the device embodiments are examples of devices for implementing functions performed by the elements for the purpose of implementing the invention.

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Abstract

一种核燃料颗粒包覆层厚度检测方法，包括：在第一放大倍数下，采集待测样品的表面图像，待测样品的表面包括多个核燃料颗粒的剖面（S310）；确定表面图像中的可测颗粒，其中，可测颗粒为剖面面积大于第一阈值且与周围颗粒的平均间距小于第二阈值的核燃料颗粒（S320）；在第二放大倍数下，采集可测颗粒的剖面图像，其中，第二放大倍数大于所述第一放大倍数（S330）；确定剖面图像中可测颗粒的中心和各包覆层的轮廓线，根据中心和各包覆层的轮廓线来确定各包覆层的厚度（S340）。还提供一种核燃料颗粒包覆层厚度检测装置。

Description

核燃料颗粒包覆层厚度检测方法及装置 技术领域
本发明涉及测量与检测技术领域，尤其涉及一种核燃料颗粒包覆层厚度检测方法及装置。
背景技术
作为一种清洁高效的新型能源，核能已广泛应用于众多国家，对军事、经济、社会、政治等都有深远的影响。随着我国经济的快速发展和化石能源的逐渐枯竭，核能的大规模应用将成为必然选择。我国自主研发的世界首座具有第四代核电特征的高温气冷堆核电站于2012年底开工建设，和第三代核电站采用的压水堆技术不同，一般压水堆核电站能提供大约300℃的热能，而高温气冷堆能达到750℃，发电效率大大提升；并且，高温气冷堆核电站具有良好的固有安全性。
核燃料颗粒是高温气冷堆燃料球中的最小单元，由UO2核芯和其外面的包覆层构成，包覆层由四层厚度、密度各不相同的热解碳和碳化硅组成。核燃料颗粒的直径小于1mm，其中UO2核芯的直径小于0.5mm，包覆层的各层厚度只有20～140μm。UO2核芯的大小及各包覆层的厚度直接影响反应堆运行的效率和安全。因此，精确测量每一批次核燃料颗粒的各包覆层的厚度至关重要。
目前，用于检测核燃料颗粒包覆层厚度的方法主要有X射线显微成像法、V型槽法、金相法、颗粒尺寸分析仪法等。综合考虑检测成本、检测效率、检测精度以及对检测环境的需求，最适合工业应用的是金相法。金相法通常采用树脂包裹核燃料颗粒，通过磨削加工使核燃料颗粒露出核芯和各包覆层，制成磨削样片。人工通过显微镜观察样片表面，挑选出完整的、磨削状态良好的核燃料颗粒，再人工在各包覆层边界标记三点拟合圆形作为各层边界，通过圆心向外做射线，以射线与各边界交点距离作为各层厚度。该检测方法主要由人工进行，自动化程度差，测量精度低。此外，核辐射可能会危害检 测工人的身体健康。
发明内容
为此，本发明提供一种核燃料颗粒包覆层厚度检测方法及装置，以力图解决或至少缓解上面存在的问题。
根据本发明的第一个方面，提供一种核燃料颗粒包覆层厚度检测方法，包括：在第一放大倍数下，采集待测样品的表面图像，所述待测样品的表面包括多个核燃料颗粒的剖面；确定所述表面图像中的可测颗粒，其中，所述可测颗粒为剖面面积大于第一阈值且与周围颗粒的平均间距小于第二阈值的核燃料颗粒；在第二放大倍数下，采集可测颗粒的剖面图像，其中，所述第二放大倍数大于所述第一放大倍数；确定剖面图像中可测颗粒的中心和各包覆层的轮廓线，根据所述中心和各包覆层的轮廓线来确定各包覆层的厚度。
可选地，在根据本发明的核燃料颗粒包覆层厚度检测方法中，在所述采集待测样品的第一表面图像的步骤之前，还包括：在第三放大倍数下，采集待测样品的边缘图像，其中，所述第三放大倍数小于所述第一放大倍数；根据所述边缘图像来确定待测样品的中心位置，将所述待测样品的中心移动至显微镜的视野中心处。
可选地，在根据本发明的核燃料颗粒包覆层厚度检测方法中，所述在第一放大倍数下，采集待测样品的表面图像的步骤，包括：将所述待测样品的表面划分为多个区域，在第一放大倍数下，按照预设顺序依次采集各个区域的表面图像。
可选地，在根据本发明的核燃料颗粒包覆层厚度检测方法中，所述待测样品的表面被划分成多个等大的区域，在第一放大倍数下，从中心区域开始，按照顺时针或逆时针的顺序依次采集各个区域的表面图像。
可选地，在根据本发明的核燃料颗粒包覆层厚度检测方法中，所述根据所述中心和各包覆层的轮廓线来确定各包覆层的厚度的步骤，包括：从所述中心出发作至少一条射线，所述射线分别与各轮廓线交于各点；将包覆层所对应的交点距的平均值作为该包覆层的厚度，其中，所述交点距为外交点与内交点的距离，所述外交点为射线与包覆层的外轮廓线的交点，所述内交点 为射线与包覆层的内轮廓线的交点。
可选地，在根据本发明的核燃料颗粒包覆层厚度检测方法中，过所述中心作两条相互垂直的直线，所述直线分别与各轮廓线交于各点；将包覆层所对应的交点距的平均值作为该包覆层的厚度。
可选地，在根据本发明的核燃料颗粒包覆层厚度检测方法中，在所述根据所述中心和各包覆层的轮廓线来确定各包覆层的厚度的步骤之后，还包括：判断包覆层的厚度是否异常；当包覆层的厚度异常时，对可测颗粒进行复检。
可选地，在根据本发明的核燃料颗粒包覆层厚度检测方法中，所述对可测颗粒进行复检的步骤，包括：在第四放大倍数下，采集可测颗粒的局部剖面图像，其中，所述第四放大倍数大于所述第二放大倍数；确定所述局部剖面图像中可测颗粒的中心和各包覆层的轮廓线，从所述中心出发作一条射线，所述射线分别与各轮廓线交于各点；将包覆层所对应的交点距作为该包覆层的厚度。
可选地，在根据本发明的核燃料颗粒包覆层厚度检测方法中，异常包括：可测颗粒的一包覆层的厚度与其他可测颗粒的同一包覆层的厚度的均值的差的绝对值大于第三阈值。
可选地，在根据本发明的核燃料颗粒包覆层厚度检测方法中，还包括：将检测过程中采集到的图像和测得的相关数据存储至数据库。
根据本发明的第二个方面，提供一种核燃料颗粒包覆层厚度检测装置，包括：显微镜、工业相机和计算设备，所述工业相机分别与所述显微镜和所述计算设备相连；所述显微镜包括电控载物台和电控转换器，所述电控载物台用于承载所述待测样品，所述电控转换器上设置有多个不同放大倍数的物镜；所述电控载物台和电控转换器分别与所述计算设备相连，所述计算设备适于根据程序指令来控制所述电控载物台和所述电控转换器的位置，从而调整待测样品的位置以及切换物镜；所述工业相机适于采集待测样品的图像，将所述图像发送至所述计算设备，以便所述计算设备根据所述图像来确定核燃料颗粒的包覆层厚度。
可选地，在根据本发明的核燃料颗粒包覆层厚度检测装置中，计算设备包括：至少一个处理器和存储有程序指令的存储器；当所述程序指令被所述 处理器读取并执行时，使得所述核燃料颗粒包覆层厚度检测装置执行如上所述的包覆层厚度检测方法。
本发明的核燃料颗粒包覆层厚度检测方案能够在第一放大倍数下自动采集待测样品的表面图像，从中挑选出符合测量要求的可测颗粒；随后，在更高的放大倍数(即第二放大倍数)下采集可测颗粒的剖面图像，从中提取可测颗粒的中心和各包覆层的轮廓线，根据中心和轮廓线来确定各包覆层的厚度。本发明的核燃料颗粒包覆层厚度检测方案实现了对各包覆层厚度的自动化检测，与现有技术相比，自动化程度、测量效率和测量精度均得到大幅提升，能够为核反应堆元件提供更为精确的测量数据，并避免检测工人遭受辐射伤害。
上述说明仅是本发明技术方案的概述，为了能够更清楚了解本发明的技术手段，而可依照说明书的内容予以实施，并且为了让本发明的上述和其它目的、特征和优点能够更明显易懂，以下特举本发明的具体实施方式。
附图说明
为了实现上述以及相关目的，本文结合下面的描述和附图来描述某些说明性方面，这些方面指示了可以实践本文所公开的原理的各种方式，并且所有方面及其等效方面旨在落入所要求保护的主题的范围内。通过结合附图阅读下面的详细描述，本公开的上述以及其它目的、特征和优势将变得更加明显。遍及本公开，相同的附图标记通常指代相同的部件或元素。
图1示出了根据本发明一个实施例的核燃料颗粒包覆层厚度检测装置100的示意图；
图2示出了根据本发明一个实施例的计算设备130的示意图；
图3示出了根据本发明一个实施例的核燃料颗粒包覆层厚度检测方法300的流程图；
图4示出了根据本发明一个实施例的在第一放大倍数下采集到的待测样品的表面图像的示意图；
图5示出了根据本发明一个实施例的两个核燃料颗粒的间距的示意图；
图6示出了根据本发明一个实施例的在第二放大倍数下采集到的可测颗 粒的剖面图像的示意图；
图7示出了根据本发明另一个实施例的核燃料颗粒包覆层厚度检测方法700的流程图；
图8示出了根据本发明一个实施例的在第三放大倍数下采集到的待测样品的边缘图像的示意图；
图9示出了根据本发明一个实施例的待测样品的表面区域划分的示意图；
图10示出了根据本发明一个实施例的在第四放大倍数下采集到的可测颗粒的局部剖面图像的示意图。
具体实施方式
下面将参照附图更详细地描述本公开的示例性实施例。虽然附图中显示了本公开的示例性实施例，然而应当理解，可以以各种形式实现本公开而不应被这里阐述的实施例所限制。相反，提供这些实施例是为了能够更透彻地理解本公开，并且能够将本公开的范围完整的传达给本领域的技术人员。
图1示出了根据本发明一个实施例的核燃料颗粒包覆层厚度检测装置100的示意图，装置100能够实现对核燃料颗粒的各包覆层厚度的自动化检测。如图1所示，装置100包括显微镜110、工业相机120和计算设备130(计算设备130未在图1中示出)。
显微镜110可以是任意型号，本发明对显微镜110的生产厂商及型号不做限制。如图1所示，在本发明的实施例中，显微镜110包括电控转换器111和电控载物台112。
电控转换器111上设置有多个不同放大倍数的物镜114，通过转动电控转换器111，可以实现物镜114的切换，从而调整显微镜110的放大倍数。本发明对物镜114的数量及放大倍数不做限制。优选地，显微镜110包括四个物镜114，其放大倍数分别为2X、5X、10X、40X。
电控载物台112用于承载待测样品200，通过调整电控载物台112在空间XYZ轴的位置，可以实现物镜114、工业相机120的自动对焦以及调整待测样品200在显微镜视野中的位置。需要说明的是，本发明对电控载物台112在XYZ轴的行程范围不做限制。根据一种实施例，电控载物台112在XY轴 方向上分别具有50mm以上的行程，在Z轴方向上具有10mm以上的行程。
待测样品200中包括多个核燃料颗粒，且其表面包括多个核燃料颗粒的剖面。本发明的实施例通过在不同放大倍数下采集待测样品200表面的图像，并对采集到的图像进行分析处理，可以检测出核燃料颗粒各包覆层的厚度。待测样品200例如可以采用镶样和磨削工艺制成，即：首先，将核燃料颗粒倒入镶样模具中，使核燃料颗粒紧密排列。随后，向镶样模具中倒入固化剂，采用镶嵌工艺将核燃料颗粒固定包裹于固化剂中，形成与模具形状一致的固态样品。固化剂例如可以是树脂等材料，但不限于此。随后，对固态样品的表面进行研磨，使核燃料颗粒露出核芯和各包覆层(即呈现出核燃料颗粒的剖面)，制成待测样品200。需要说明的是，待测样品200可以是任意形状、任意尺寸，具体地，待测样品200的形状及尺寸根据镶样模具的形状、尺寸以及磨削过程所去除的样品材料的多少而定，本发明对待测样品200的形状及尺寸不做限制。下文(图4～6、8～10的实施例)将以待测样品200为一定高度的圆柱状样品为例，来说明本发明的包覆层厚度检测方案。
另外，需要说明的是，待测样品200中所包括的核燃料颗粒可以是任意结构、任意材料，本发明对核燃料颗粒的核芯的种类、包覆层的数量、厚度、材料等均不做限制。下文(图4～6、8～10的实施例)将以四层包覆层的核燃料颗粒为例，来说明本发明的包覆层厚度检测方案。
工业相机120可以是任意型号，本发明对工业相机120的生产厂商及型号不做限制。例如，工业相机120可以具有1英寸的传感器芯片、1200万的真实物理像素、4000*3000的分辨率、C型相机接口、15幅每秒的帧率。工业相机120分别与显微镜110和计算设备130相连，例如，工业相机120通过相机接口122与显微镜110相连，通过USB等数据线与计算设备130相连。工业相机120用于采集经显微镜110放大的待测样品的图像，将图像发送至计算设备130进行图像处理，以检测核燃料颗粒各包覆层的厚度。
计算设备130可以是任意具有存储和计算能力的设备，其例如可以是桌面电脑、笔记本电脑等个人配置的计算机，也可以是工作站、服务器等硬件配置较高的计算机，还可以是手机、平板电脑、智能可穿戴设备等移动终端，但不限于此。
在本发明的实施例中，工业相机120、电控转换器111和电控载物台112分别与计算设备130相连。计算设备130可以根据程序指令来控制电控转换器111和电控载物台112的位置，从而切换物镜114以及调整待测样品200的位置。工业相机120适于采集不同放大倍数下的待测样品的图像，将图像发送至计算设备130，计算设备130基于预设的程序指令，对该图像进行分析处理，根据该图像来确定核燃料颗粒的包覆层厚度。
图2示出了根据本发明一个实施例的计算设备130的示意图。需要说明的是，图2所示的计算设备130仅为一个示例，在实践中，用于实施本发明的核燃料颗粒包覆层厚度检测方法的计算设备可以是任意型号的设备，其硬件配置情况可以与图2所示的计算设备130相同，也可以不同。实践中用于实施本发明的核燃料颗粒包覆层厚度检测方法的计算设备可以对图2所示的计算设备130的硬件组件进行增加或删减，本发明对计算设备的具体硬件配置情况不做限制。
如图2所示，在基本的配置102中，计算设备130典型地包括系统存储器106和一个或者多个处理器104。存储器总线108可以用于在处理器104和系统存储器106之间的通信。
取决于期望的配置，处理器104可以是任何类型的处理，包括但不限于：微处理器(μP)、微控制器(μC)、数字信息处理器(DSP)或者它们的任何组合。处理器104可以包括诸如一级高速缓存110和二级高速缓存112之类的一个或者多个级别的高速缓存、处理器核心114和寄存器116。示例的处理器核心114可以包括运算逻辑单元(ALU)、浮点数单元(FPU)、数字信号处理核心(DSP核心)或者它们的任何组合。示例的存储器控制器118可以与处理器104一起使用，或者在一些实现中，存储器控制器118可以是处理器104的一个内部部分。
取决于期望的配置，系统存储器106可以是任意类型的存储器，包括但不限于：易失性存储器(诸如RAM)、非易失性存储器(诸如ROM、闪存等)或者它们的任何组合。系统存储器106可以包括操作系统120、一个或者多个程序122以及程序数据124。在一些实施方式中，程序122可以布置为在操作系统上由一个或多个处理器104利用程序数据124执行指令。
计算设备130还可以包括有助于从各种接口设备(例如，输出设备142、外设接口144和通信设备146)到基本配置102经由总线/接口控制器131的通信的接口总线140。示例的输出设备142包括图形处理单元148和音频处理单元150。它们可以被配置为有助于经由一个或者多个A/V端口152与诸如显示器或者扬声器之类的各种外部设备进行通信。示例外设接口144可以包括串行接口控制器154和并行接口控制器156，它们可以被配置为有助于经由一个或者多个I/O端口158和诸如输入设备(例如，键盘、鼠标、笔、语音输入设备、触摸输入设备)或者其他外设(例如打印机、扫描仪等)之类的外部设备进行通信。示例的通信设备146可以包括网络控制器160，其可以被布置为便于经由一个或者多个通信端口164与一个或者多个其他计算设备162通过网络通信链路的通信。
网络通信链路可以是通信介质的一个示例。通信介质通常可以体现为在诸如载波或者其他传输机制之类的调制数据信号中的计算机可读指令、数据结构、程序模块，并且可以包括任何信息递送介质。“调制数据信号”可以这样的信号，它的数据集中的一个或者多个或者它的改变可以在信号中编码信息的方式进行。作为非限制性的示例，通信介质可以包括诸如有线网络或者专线网络之类的有线介质，以及诸如声音、射频(RF)、微波、红外(IR)或者其它无线介质在内的各种无线介质。这里使用的术语计算机可读介质可以包括存储介质和通信介质二者。
在根据本发明的计算设备130中，应用122包括用于执行核燃料颗粒包覆层厚度检测方法300的指令，该指令可以指示前述核燃料颗粒包覆层厚度检测装置100执行本发明的核燃料颗粒包覆层厚度检测方法300，通过自动切换物镜、自动对焦、自动调整待测样品的位置，在显微镜的不同放大倍数下采集待测样品的图像，对图像进行分析处理以确定核燃料颗粒各包覆层的厚度，实现包覆层厚度的自动化检测。
图3示出了根据本发明一个实施例的核燃料颗粒包覆层厚度检测方法300的流程图。方法300由前述核燃料颗粒包覆层厚度检测装置100执行。如图3所示，方法300始于步骤S310。
在步骤S310中，在第一放大倍数下，采集待测样品的表面图像，待测样品的表面包括多个核燃料颗粒的剖面。
根据一种实施例，待测样品为对多个核燃料颗粒进行镶样、磨削所制成的圆柱状样品，其表面由于进行了磨削而显露出多个核燃料颗粒的核芯和各包覆层，即显露出多个核燃料颗粒的剖面。
需要说明的是，在第一放大倍数下所采集到的表面图像中，应当能够示出多个核燃料颗粒的剖面。本发明对第一放大倍数的具体数值不做限制，本领域技术人员可以根据核燃料颗粒的实际尺寸来选择合适放大倍数的物镜，使表面图像中能够显示出多个核燃料颗粒的剖面。例如，在一个实施例中，核燃料颗粒的直径约为1mm，相应地，可以采用成像视野直径约为4mm、放大倍数为5X的物镜(即第一放大倍数为5)，这时，工业相机所采集到的待测样品的表面图像中将包括多个核燃料颗粒的剖面。
具体地，在步骤S310中，首先将待测样品通过载玻片、夹具等结构固定于电控载物台112上。随后，根据计算设备130中预设的程序指令，自动调整电控转换器111，将正对载物台的物镜切换成具有第一放大倍数的物镜。自动调整电控载物台112的位置，将待测样品移至物镜的视野中，并进行自动对焦，使工业相机120中能够呈现出待测样品表面的清晰图像。随后，工业相机120采集待测样品的表面图像，并将采集到的表面图像发送至计算设备130进行分析处理。
随后，计算设备130执行步骤S320。
在步骤S320中，确定表面图像中的可测颗粒，其中，可测颗粒为剖面面积大于第一阈值且与周围颗粒的平均间距小于第二阈值的核燃料颗粒。
通过判断剖面面积是否大于第一阈值，可以判断出核燃料颗粒的完整性，即判断核燃料颗粒在磨削过程中是否发生核芯以及包覆层的剥落。通过判断核燃料颗粒与周围颗粒的平均间距是否小于第二阈值，可以判断出核燃料颗粒的磨削状态是否良好，是否发生欠磨削或过磨削。在良好的磨削状态中，核燃料颗粒的剖面应当经过核燃料颗粒的球心，或与球心的距离十分接近。
根据一种实施例，步骤S320进一步可以按照以下步骤S322～S326来实施：
在步骤S322中，确定表面图像中各核燃料颗粒的中心，从而确定各核燃料颗粒的位置。
根据一种实施例，可以将表面图像转换成灰度图像，并进一步转换成二 值图像。对二值图像进行形态学处理(例如形态学开运算等)，以消除二值图像中的孤立点、毛刺以及结构之间的细微粘连，使二值图像中呈现出多个相互分离的、单独的核燃料颗粒。随后，采用形状检测算法(例如霍夫变换算法等)来识别出二值图像中的圆形轮廓，并确定其圆心。
随后，在步骤S324中，判断核燃料颗粒的剖面面积是否大于第一阈值。
根据一种实施例，可以以步骤S322中确定的各颗粒的圆心为中心，以等大的裁剪矩形将各颗粒的图像裁剪出来，根据裁剪出来的图像来判断相应的核燃料颗粒的剖面面积是否大于第一阈值。裁剪矩形的尺寸可以根据核燃料颗粒的实际尺寸来确定，在一个实施例中，可以将裁剪矩形的尺寸设置成比核燃料颗粒的外接矩形稍大。例如，核燃料颗粒的剖面约为直径为1mm的圆形，其外接矩形为1mm*1mm的正方形，相应地，可以将裁剪矩形设置成1.2mm*1.2mm的正方形。
根据一种实施例，将裁剪出来的单个核燃料颗粒的图像进行二值化，得到二值图像。
若核燃料颗粒的结构完整，则在原始表面图像中，该颗粒呈现为亮区域，如图4所示，实线矩形框1～7中的核燃料颗粒均为完整颗粒。在将完整的核燃料颗粒的图像进行二值化后，该核燃料颗粒在二值图像中将呈现为一个白色的圆形。
若核燃料颗粒在磨削过程中，核芯或包覆层被剥落，则在原始表面图像中，该颗粒被剥落的部位呈现为暗区域，如图4所示，虚线矩形框8中的核燃料颗粒为不完整的颗粒，其核芯及内侧的三个包覆层均在磨削过程中被剥落。在将不完整的核燃料颗粒的图像进行二值化后，被剥落的部位将在二值图像中呈现为黑色，相应地，整个核燃料颗粒不会呈现出一个白色的圆形，而是呈现为一个白色的圆环，或者完全呈现为黑色。
随后，计算二值图像中像素值为1的像素的数量，即，计算二值图像中的白色区域的面积，将计算结果作为核燃料颗粒的剖面面积。随后，判断剖面面积是否大于第一阈值，若剖面面积大于第一阈值，则表示核燃料颗粒结构完整，继续执行步骤S326，进一步判断该核燃料颗粒与周围颗粒的平均间距是否大于第二阈值，即判断该核燃料颗粒的磨削状态是否良好。若剖面面 积小于等于第一阈值，则表示该核燃料颗粒不完整，判定该颗粒不是可测颗粒。需要说明的是，第一阈值可以由本领域人员参考核燃料颗粒的实际尺寸来设定，本发明对第一阈值的取值不做限制。
在步骤S326中，判断完整的核燃料颗粒与周围颗粒的平均间距是否小于第二阈值。
两个核燃料颗粒之间的间距为一个颗粒的最外层轮廓上的一点到另一颗粒的最外层轮廓上的一点的距离的最小值。具体地，在测定两个核燃料颗粒之间的间距时，可以将两个颗粒的圆心O1、O2相连，得到线段O1O2。线段O1O2分别与两个颗粒的最外层轮廓交于点A、点B，点A到点B的距离即为这两个颗粒之间的间距。例如，如图5所示，两个核燃料颗粒的圆心分别为O1、O2，线段O1O2分别与两个颗粒的最外层轮廓交于点A、点B。点A、点B在图像中的坐标分别为(1128，987)，(1133，998)。根据二者的坐标计算点A到点B的距离，为12.08px。
本领域技术人员可以理解，一个核燃料颗粒的周围颗粒通常有多个。在这种情况下，分别计算该核燃料颗粒与每一个周围颗粒之间的间距，得到多个间距。随后，计算多个间距的平均值，即，计算平均间距。随后，判断平均间距是否小于第二阈值，若是，则表明该燃料颗粒的磨削状态良好，判定该颗粒为可测颗粒；若否，则表明该燃料颗粒欠磨削或过磨削，判定该颗粒不是可测颗粒。
需要说明的是，第二阈值可以由本领域人员自行设定，本发明对第二阈值的取值不做限制。此外，本发明对第二阈值的单位亦不做限制，不过第二阈值的单位应当与步骤S320中测得的平均间距的单位一致。例如，平均间距的单位为px(像素)，则第二阈值的也应当为px；根据像素当量，将像素距离转化为长度距离后，平均间距的单位为μm、nm等长度单位，则第二阈值的单位也应当为μm、nm等长度单位。
经过步骤S320，可以确定表面图像中的可测颗粒。例如，如图4所示，实线矩形框1～7中的核燃料颗粒为可测颗粒。
在确定表面图像中的可测颗粒后，执行步骤S330。
在步骤S330中，在第二放大倍数下，采集可测颗粒的剖面图像，其中， 第二放大倍数大于第一放大倍数。
需要说明的是，在第二放大倍数下所采集到的剖面图像中，应当能够清晰、完整地示出一个可测颗粒的剖面，并且优选地，仅能示出一个可测颗粒的剖面。本发明对第二放大倍数的具体数值不做限制，本领域技术人员可以根据核燃料颗粒的实际尺寸来选择合适放大倍数的物镜，使剖面图像中能且仅能示出一个可测颗粒的完整剖面。例如，在一个实施例中，核燃料颗粒的直径约为1mm，相应地，可以采用成像视野直径约为1.5mm、放大倍数为10X的物镜(即第二放大倍数为10)，这时，工业相机所采集到的可测颗粒的剖面图像中将仅包含一个可测颗粒的剖面。
具体地，在步骤S330中，根据计算设备130中预设的程序指令，自动调整电控转换器111，将正对载物台的物镜切换成具有第二放大倍数的物镜。随后，自动调整电控载物台112的位置，将可测颗粒移至物镜的视野中，并进行自动对焦，使工业相机120中能够呈现出可测颗粒的清晰图像。随后，工业相机120采集可测颗粒的剖面图像，并将采集到的图像发送至计算设备130进行分析处理。
随后，计算设备130执行步骤S340。
在步骤S340中，确定剖面图像中可测颗粒的中心和各包覆层的轮廓线，根据中心和各包覆层的轮廓线来确定各包覆层的厚度。
可测颗粒的中心和各包覆层的轮廓线可以采用形状检测算法来确定。形状检测算法例如可以是霍夫变换(Hough Transform)算法、拉东变换(Radon Transform)算法等，但不限于此。
根据一种实施例，在确定了可测颗粒的中心和各包覆层的轮廓线之后，可以按照以下步骤S342、S344来确定各包覆层的厚度：
在步骤S342中，从可测颗粒的中心出发作至少一条射线，每一条射线分别与各轮廓线交于各点。
需要说明的是，本发明对步骤S342中所作的射线的数量及方向均不做限制。根据一种实施例，如图6所示，可以过中心点O作两条相互垂直的直线，两条直线分别与各轮廓线交于A1～E1、A1～E2、A3～E3、A4～E4各点。换言之，过中心作四条射线，相邻射线之间的夹角为90°，这四条射线分别与各轮 廓线交于各点。
随后，在步骤S344中，将包覆层所对应的交点距的平均值作为该包覆层的厚度，其中，交点距为外交点与内交点的距离，外交点为射线与包覆层的外轮廓线的交点，内交点为射线与包覆层的内轮廓线的交点。
例如，如图6所示，可测颗粒包括四个包覆层，由内向外分别为包覆层a、包覆层b、包覆层c、包覆层d。图中四条射线与包覆层a的内轮廓线的交点分别为A1～A4，与包覆层a的外轮廓线的交点分别为B1～B4，即，包覆层a的内交点为A1～A4，外交点为B1～B4。相应地，包覆层a对应于四个交点距，分别为B1-A1、B2-A2、B3-A3、B4-A4。包覆层a的厚度为四个交点距的平均值，即(B1-A1+B2-A2+B3-A3+B4-A4)/4。同理，包覆层b、c、d的厚度分别为(C1-B1+C2-B2+C3-B3+C4-B4)/4，(D1-C1+D2-C2+D3-C3+D4-C4)/4，(E1-D1+E2-D2+E3-D3+E4-D4)/4。
根据另一种实施例，可以拟合出各轮廓线的半径，将一包覆层的外轮廓线半径与内轮廓线半径之差作为该包覆层的厚度。例如，如图6所示，拟合出可测颗粒由内到外的五个轮廓线的半径分别为R1～R5，则包覆层a～d的厚度分别为R2-R1、R3-R2、R4-R3、R5-R4。
经过步骤S340，即可测得可测颗粒的各包覆层的厚度。
根据一种实施例，方法300还包括步骤：将检测过程中采集到的图像和测得的相关数据存储至数据库。采集到的图像包括前述第一放大倍数下的表面图像、标记了可测颗粒的表面图像、第二放大倍数下的剖面图像等，但不限于此。相关数据例如包括各可测颗粒的包覆层厚度数据、中心坐标等，但不限于此。
本领域技术人员可以根据实际需要，选择将检测过程中涉及到的图像和相关数据的部分或全部进行存储，本发明对存储至数据库的具体数据内容不做限制。例如，本领域技术人员可以选择将可测颗粒的剖面图像和测得的各包覆层的厚度数据存储至数据库。基于已存储的厚度数据，可以计算出某一批次的核燃料颗粒的包覆层厚度的统计值，例如各包覆层厚度的最大值、最小值、平均值、方差、标准差等数据，但不限于此。
图7示出了根据本发明另一个实施例的核燃料颗粒包覆层厚度检测方法700的流程图。方法700由前述核燃料颗粒包覆层厚度检测装置100执行。与前述方法300相比，方法700所检测的核燃料颗粒更为全面、检测过程的自动化程度更高。如图7所示，方法700始于步骤S710。
在步骤S710中，在第三放大倍数下，采集待测样品的边缘图像。
需要说明的是，在第三放大倍数下所采集到的边缘图像中，应当能够示出待测样品的圆弧边缘。本发明对第三放大倍数的具体数值不做限制，本领域技术人员可以根据待测样品的实际尺寸来选择合适放大倍数的物镜，使边缘图像中能够显示出待测样品的圆弧边缘。例如，在一个实施例中，可以采用成像视野直径约为8mm、放大倍数为2X的物镜(即第三放大倍数为2)。
具体地，在步骤S710中，首先将待测样品通过载玻片、夹具等结构固定于电控载物台112上。随后，根据计算设备130中预设的程序指令，自动调整电控转换器111，将正对载物台的物镜切换成具有第三放大倍数的物镜。自动调整电控载物台112的位置，将待测样品移至物镜的视野中，并进行自动对焦，使工业相机120中能够呈现出待测样品表面的清晰图像。随后，工业相机120采集待测样品的边缘图像，并将采集到的边缘图像发送至计算设备130进行分析处理。图8示出了在第三放大倍数下所采集到的边缘图像的一个示例。
在步骤S720中，根据边缘图像来确定待测样品的中心位置，将待测样品的中心移动至显微镜的视野中心。
根据一种实施例，计算设备130可以采用轮廓提取算法提取待测样品的边缘弧形轮廓，采用圆形来拟合样品边缘，确定其中心(圆心)位置和半径大小。本领域技术人员可以理解，通过圆形拟合所确定的待测样品的中心可能位于边缘图像的像素坐标范围之外。随后，调整电控载物台112的位置，将待测样品的中心移动至显微镜的视野中心。
随后，在步骤S730中，将待测样品的表面划分为多个区域，在第一放大倍数下，按照预设顺序依次采集各个区域的表面图像，其中，第一放大倍数大于第三放大倍数。
通过在第一放大倍数下依次采集各个区域的表面图像，可以实现对待测 样品的全面检测。需要说明的是，本发明对待测样品表面的区域划分方式(区域的数量、大小等)以及各区域图像的采集顺序不做限制。优选地，每个区域中均应当包括多个核燃料颗粒的剖面。
根据一种实施例，可以将待测样品的表面划分为多个等大的区域，在1放大倍数下，从中心区域开始，按照顺时针或逆时针的顺序依次采集各个区域的表面图像。例如，如图9所示，待测样品的表面被划分为52个矩形区域，从中心区域1开始，在第一放大倍数下，按照逆时针的方向依次采集各个区域的表面图像。对于每个区域，均需要按照后续步骤S740～S780，确定该区域中的可测颗粒并检测可测颗粒的各包覆层厚度，从而实现对待测样品的全面检测。
随后，在步骤S740中，确定表面图像中的可测颗粒，其中，可测颗粒为剖面面积大于第一阈值且与周围颗粒的平均间距小于第二阈值的核燃料颗粒。
随后，在步骤S750中，在第二放大倍数下，采集可测颗粒的剖面图像，其中，第二放大倍数大于第一放大倍数。
随后，在步骤S760中，确定剖面图像中可测颗粒的中心和各包覆层的轮廓线，根据中心和各包覆层的轮廓线来确定各包覆层的厚度。
步骤S740～S760与前述步骤S320～S340相同。步骤S740～S760的具体实施方式可以参考前述步骤S320～S340的相关描述，此处不再赘述。
随后，在步骤S770中，当包覆层的厚度异常时，在第四放大倍数下，对可测颗粒进行复检，其中，第四放大倍数大于第二放大倍数。
在步骤S770中，判断包覆层的厚度是否异常，当包覆层的厚度异常时，对相应的可测颗粒进行复检。异常的判断标准可以由本领域技术人员自行设定，本发明对此不做限制。在一个实施例中，可以将异常的判断标准设置为：可测颗粒的一包覆层的厚度与其他可测颗粒的同一包覆层的厚度的均值的差的绝对值大于第三阈值。例如，可测颗粒P包括a～d四个包覆层，其中，包覆层a的厚度为tha；其他可测颗粒的包覆层a的厚度的平均值为tha，当
Figure PCTCN2019094207-appb-000001
大于第三阈值时，判断可测颗粒P的包覆层a的厚度数据出现异常，需要对可测颗粒P进行复检。第三阈值的取值可以由本领域技术人员自行设 置，本发明对此不做限制。
根据一种实施例，可以按照以下步骤对可测颗粒进行复检：
在第四放大倍数下，采集可测颗粒的局部剖面图像，其中，第四放大倍数大于前述第二放大倍数；确定局部剖面图像中可测颗粒的中心和各包覆层的轮廓线，从中心出发作一条射线，该射线分别与各轮廓线交于各点；将包覆层所对应的交点距作为该包覆层的厚度。
需要说明的是，第四放大倍数大于前述第二放大倍数，在第四放大倍数下所采集到的局部剖面图像中，仅能够示出单个可测颗粒的局部边缘。本发明对第四放大倍数的具体数值不做限制，本领域技术人员可以根据核燃料颗粒的实际尺寸来选择合适放大倍数的物镜，使局部剖面图像中仅能示出一个可测颗粒的局部边缘。例如，在一个实施例中，核燃料颗粒的直径约为1mm，相应地，可以采用成像视野直径约为0.4mm、放大倍数为40X的物镜(即第四放大倍数为40)，这时，工业相机所采集到的可测颗粒的局部剖面图像中仅包含一个可测颗粒的局部边缘。图10示出了在第四放大倍数下所采集到的局部剖面图像的一个示例。
采集到局部剖面图像之后，确定局部剖面图像中可测颗粒的中心和各包覆层的轮廓线，从中心出发作一条射线，该射线分别与各轮廓线交于各点；将包覆层所对应的交点距作为该包覆层的厚度。
根据一种实施例，可以采用轮廓提取算法来提取可测颗粒的各包覆层边缘的弧形边缘轮廓，采用圆形来拟合弧形边缘，确定其中心(圆心)位置。本领域技术人员可以理解，通过圆形拟合所确定的可测颗粒的中心可能位于局部剖面图像的像素坐标范围之外。随后，可以从中心出发作一条射线，该射线分别与各轮廓线交于各点；将包覆层所对应的交点距作为该包覆层的厚度。例如，如图10所示，从中心(位于图像之外)出发作一条射线，该射线分别与各轮廓线交于A～E五个点。相应地，包覆层a～d的厚度分别为B-A、C-B、D-C、E-D。
根据另一种实施例，可以拟合出各轮廓线的半径，将一包覆层的外轮廓线半径与内轮廓线半径之差作为该包覆层的厚度。例如，在图10所示的示例中，拟合出可测颗粒由内到外的五个轮廓线的半径分别为R1～R5，则包覆层 a～d的厚度分别为R2-R1、R3-R2、R4-R3、R5-R4。
随后，在步骤S780中，将检测过程中采集到的图像和测得的相关数据存储至数据库；根据已存储的数据，输出整体检测结果。
检测过程中采集到的图像包括：第三放大倍数下的边缘图像、第一放大倍数下的各区域的表面图像、标记了可测颗粒的各区域的表面图像、第二放大倍数下的剖面图像、第四放大倍数下的局部剖面图像等，但不限于此。相关数据例如包括各可测颗粒的包覆层厚度数据、中心坐标等，但不限于此。
本领域技术人员可以根据实际需要，选择将检测过程中涉及到的图像和相关数据的部分或全部进行存储，本发明对存储至数据库的具体数据内容不做限制。例如，本领域技术人员可以选择将可测颗粒的剖面图像和测得的各包覆层的厚度数据存储至数据库。
另外，应当指出，虽然在图7所示的实施例中，步骤S780为方法700的最后一个步骤，但本领域技术人员可以理解，数据存储过程通常贯穿整个厚度检测过程，即，在步骤S710～S770的执行过程中，每产生需要存储的图像或相关数据，旋即将其存储至数据库，而不必等待所有步骤执行完毕后再存储相关数据。
基于数据库中已存储的数据，可以统计得出整体的检测结果。检测结果数据例如包括：待测样品上的燃料颗粒个数、可测颗粒比例、单个燃料颗粒的各包覆层厚度、燃料颗粒各包覆层的平均厚度、包覆层厚度分布情况、包覆层厚度偏差范围，以及根据测量结果输出的相应判断数据(例如某一批次的核燃料颗粒是否符合要求等)等，但不限于此。
本发明的核燃料颗粒包覆层厚度检测方案实现了对各包覆层厚度的自动化检测，与现有技术相比，自动化程度、测量效率和测量精度均得到大幅提升，能够为核反应堆元件提供更为精确的测量数据，并避免检测工人遭受辐射伤害。
这里描述的各种技术可结合硬件或软件，或者它们的组合一起实现。从而，本发明的方法和设备，或者本发明的方法和设备的某些方面或部分可采取嵌入有形媒介，例如可移动硬盘、U盘、软盘、CD-ROM或者其它任意机器可读的存储介质中的程序代码(即指令)的形式，其中当程序被载入诸如计算 机之类的机器，并被所述机器执行时，所述机器变成实践本发明的设备。
在程序代码在可编程计算机上执行的情况下，计算设备一般包括处理器、处理器可读的存储介质(包括易失性和非易失性存储器和/或存储元件)，至少一个输入装置，和至少一个输出装置。其中，存储器被配置用于存储程序代码；处理器被配置用于根据该存储器中存储的所述程序代码中的指令，执行本发明的核燃料颗粒包覆层厚度检测方法。
以示例而非限制的方式，可读介质包括可读存储介质和通信介质。可读存储介质存储诸如计算机可读指令、数据结构、程序模块或其它数据等信息。通信介质一般以诸如载波或其它传输机制等已调制数据信号来体现计算机可读指令、数据结构、程序模块或其它数据，并且包括任何信息传递介质。以上的任一种的组合也包括在可读介质的范围之内。
在此处所提供的说明书中，算法和显示不与任何特定计算机、虚拟系统或者其它设备固有相关。各种通用系统也可以与本发明的示例一起使用。根据上面的描述，构造这类系统所要求的结构是显而易见的。此外，本发明也不针对任何特定编程语言。应当明白，可以利用各种编程语言实现在此描述的本发明的内容，并且上面对特定语言所做的描述是为了披露本发明的最佳实施方式。
在此处所提供的说明书中，说明了大量具体细节。然而，能够理解，本发明的实施例可以在没有这些具体细节的情况下被实践。在一些实例中，并未详细示出公知的方法、结构和技术，以便不模糊对本说明书的理解。
类似地，应当理解，为了精简本公开并帮助理解各个发明方面中的一个或多个，在上面对本发明的示例性实施例的描述中，本发明的各个特征有时被一起分组到单个实施例、图、或者对其的描述中。然而，并不应将该公开的方法解释成反映如下意图：即所要求保护的本发明要求比在每个权利要求中所明确记载的特征更多特征。更确切地说，如下面的权利要求书所反映的那样，发明方面在于少于前面公开的单个实施例的所有特征。因此，遵循具体实施方式的权利要求书由此明确地并入该具体实施方式，其中每个权利要求本身都作为本发明的单独实施例。
本领域那些技术人员应当理解在本文所公开的示例中的设备的模块或单 元或组件可以布置在如该实施例中所描述的设备中，或者可替换地可以定位在与该示例中的设备不同的一个或多个设备中。前述示例中的模块可以组合为一个模块或者此外可以分成多个子模块。
本领域那些技术人员可以理解，可以对实施例中的设备中的模块进行自适应性地改变并且把它们设置在与该实施例不同的一个或多个设备中。可以把实施例中的模块或单元或组件组合成一个模块或单元或组件，以及此外可以把它们分成多个子模块或子单元或子组件。除了这样的特征和/或过程或者单元中的至少一些是相互排斥之外，可以采用任何组合对本说明书(包括伴随的权利要求、摘要和附图)中公开的所有特征以及如此公开的任何方法或者设备的所有过程或单元进行组合。除非另外明确陈述，本说明书(包括伴随的权利要求、摘要和附图)中公开的每个特征可以由提供相同、等同或相似目的的替代特征来代替。
此外，本领域的技术人员能够理解，尽管在此所述的一些实施例包括其它实施例中所包括的某些特征而不是其它特征，但是不同实施例的特征的组合意味着处于本发明的范围之内并且形成不同的实施例。例如，在下面的权利要求书中，所要求保护的实施例的任意之一都可以以任意的组合方式来使用。
此外，所述实施例中的一些在此被描述成可以由计算机系统的处理器或者由执行所述功能的其它装置实施的方法或方法元素的组合。因此，具有用于实施所述方法或方法元素的必要指令的处理器形成用于实施该方法或方法元素的装置。此外，装置实施例的在此所述的元素是如下装置的例子：该装置用于实施由为了实施该发明的目的的元素所执行的功能。
如在此所使用的那样，除非另行规定，使用序数词“第一”、“第二”、“第三”等等来描述普通对象仅仅表示涉及类似对象的不同实例，并且并不意图暗示这样被描述的对象必须具有时间上、空间上、排序方面或者以任意其它方式的给定顺序。
尽管根据有限数量的实施例描述了本发明，但是受益于上面的描述，本技术领域内的技术人员明白，在由此描述的本发明的范围内，可以设想其它实施例。此外，应当注意，本说明书中使用的语言主要是为了可读性和教导 的目的而选择的，而不是为了解释或者限定本发明的主题而选择的。因此，在不偏离所附权利要求书的范围和精神的情况下，对于本技术领域的普通技术人员来说许多修改和变更都是显而易见的。对于本发明的范围，对本发明所做的公开是说明性的而非限制性的，本发明的范围由所附权利要求书限定。

Claims (12)

  1. 一种核燃料颗粒包覆层厚度检测方法，包括：
    在第一放大倍数下，采集待测样品的表面图像，所述待测样品的表面包括多个核燃料颗粒的剖面；
    确定所述表面图像中的可测颗粒，其中，所述可测颗粒为剖面面积大于第一阈值且与周围颗粒的平均间距小于第二阈值的核燃料颗粒；
    在第二放大倍数下，采集可测颗粒的剖面图像，其中，所述第二放大倍数大于所述第一放大倍数；
    确定剖面图像中可测颗粒的中心和各包覆层的轮廓线，根据所述中心和各包覆层的轮廓线来确定各包覆层的厚度。
  2. 如权利要求1所述的方法，在所述采集待测样品的第一表面图像的步骤之前，还包括：
    在第三放大倍数下，采集待测样品的边缘图像，其中，所述第三放大倍数小于所述第一放大倍数；
    根据所述边缘图像来确定待测样品的中心位置，将所述待测样品的中心移动至显微镜的视野中心处。
  3. 如权利要求1或2所述的方法，其中，所述在第一放大倍数下，采集待测样品的表面图像的步骤，包括：
    将所述待测样品的表面划分为多个区域，在第一放大倍数下，按照预设顺序依次采集各个区域的表面图像。
  4. 如权利要求3所述的方法，其中，所述待测样品的表面被划分成多个等大的区域，在第一放大倍数下，从中心区域开始，按照顺时针或逆时针的顺序依次采集各个区域的表面图像。
  5. 如权利要求1-4中任一项所述的方法，其中，所述根据所述中心和各包覆层的轮廓线来确定各包覆层的厚度的步骤，包括：
    从所述中心出发作至少一条射线，所述射线分别与各轮廓线交于各点；
    将包覆层所对应的交点距的平均值作为该包覆层的厚度，其中，所述交 点距为外交点与内交点的距离，所述外交点为射线与包覆层的外轮廓线的交点，所述内交点为射线与包覆层的内轮廓线的交点。
  6. 如权利要求5所述的方法，其中，过所述中心作两条相互垂直的直线，所述直线分别与各轮廓线交于各点；
    将包覆层所对应的交点距的平均值作为该包覆层的厚度。
  7. 如权利要求1-6中任一项所述的方法，其中，在所述根据所述中心和各包覆层的轮廓线来确定各包覆层的厚度的步骤之后，还包括：
    判断包覆层的厚度是否异常；
    当包覆层的厚度异常时，对可测颗粒进行复检。
  8. 如权利要求7所述的方法，其中，所述对可测颗粒进行复检的步骤，包括：
    在第四放大倍数下，采集可测颗粒的局部剖面图像，其中，所述第四放大倍数大于所述第二放大倍数；
    确定所述局部剖面图像中可测颗粒的中心和各包覆层的轮廓线，从所述中心出发作一条射线，所述射线分别与各轮廓线交于各点；
    将包覆层所对应的交点距作为该包覆层的厚度。
  9. 如权利要求7所述的方法，其中，所述异常包括：
    可测颗粒的一包覆层的厚度与其他可测颗粒的同一包覆层的厚度的均值的差的绝对值大于第三阈值。
  10. 如权利要求1所述的方法，还包括：
    将检测过程中采集到的图像和测得的相关数据存储至数据库。
  11. 一种核燃料颗粒包覆层厚度检测装置，包括：显微镜、工业相机和计算设备，所述工业相机分别与所述显微镜和所述计算设备相连；
    所述显微镜包括电控载物台和电控转换器，所述电控载物台用于承载所述待测样品，所述电控转换器上设置有多个不同放大倍数的物镜；
    所述电控载物台和电控转换器分别与所述计算设备相连，所述计算设备适于根据程序指令来控制所述电控载物台和所述电控转换器的位置，从而调 整待测样品的位置以及切换物镜；
    所述工业相机适于采集待测样品的图像，将所述图像发送至所述计算设备，以便所述计算设备根据所述图像来确定核燃料颗粒的包覆层厚度。
  12. 如权利要求11所述的装置，其中，所述计算设备包括：
    至少一个处理器和存储有程序指令的存储器；
    当所述程序指令被所述处理器读取并执行时，使得所述核燃料颗粒包覆层厚度检测装置执行如权利要求1-9中任一项所述的方法。
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