JPH0735533A - Method of measuring thickness of coating layer on fuel particle and device for measuring the same - Google Patents

Abstract

PURPOSE:To measure a thickness of a coating layer on a fuel particle by converting an X-ray picked-up image into an electrical Signal indicating a tone thereof, by calculating inflection points of the tone level from the signal, and by calculating the thickness of the coating layer from the distance between the inflection points. CONSTITUTION:A device 10 for measuring a thickness of a coating layer on a fuel particle is composed of an image pick-up device 12, a differentiating part 1, a thickness computing part 14 and an output part 15. An X-ray picked-up image which is obtained by picking up an image of coated fuel particles with the use of X-rays, is converted into an electrical signal corresponding to the tone level thereof. The tone level of the image 1 is differentiated by the differentiating part 13 in accordance with an electrical signal delivered from the device 12. The thickness of the coating layer of the particles is calculated by the computing part 14 from a distance between inflection points detected by the differentiating part 13. The thus calculated thickness is delivered from the output part 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring a coating layer thickness in coated fuel particles, and more specifically, for use in, for example, HTR (high temperature gas reactor) and HTTR (high temperature engineering test research reactor). The present invention relates to a method and an apparatus for measuring a coating layer thickness in a coated fuel particle, which can automatically and efficiently measure the coating layer thickness in a coated fuel particle with high accuracy.

[0002]

2. Description of the Related Art Conventionally, the thickness of the coating layer in coated fuel particles such as double coated fuel particles and quadruple coated fuel particles has been measured as follows. Was there. For example, in the case of a double-coated fuel particle 1a in which the surface of the fuel nucleus 2 is coated with the first coating layer 3a and the second coating layer 3b in this order as shown in FIG. 2, as shown in FIG. After the heavy-coated fuel particles 1a were embedded in the resin 5, the heavy-coated fuel particles 1a were polished to the equator surface 4 of the double-coated fuel particles 1a by using a polishing machine or the like.
To prepare. Then, after enlarging the image of the equatorial plane 4 in the gold phase sample 6 using a projector, the thicknesses of the first coating layer 3a and the second coating layer 3b were visually measured based on this enlarged image. Was there. Further, for example, as shown in FIG. 4, a quadruple coating obtained by coating the surface of the fuel core 2 with a first coating layer 3a, a second coating layer 3b, a third coating layer 3c and a fourth coating layer 3d in this order. In the case of the fuel particles 1b, regarding the thickness of the third coating layer 3c and the fourth coating layer 3d, an X-ray photograph of the quadruple coated fuel particles 1b is taken. Then, the image of the X-ray photograph was enlarged using a projector, and the thicknesses of the third coating layer 3c and the fourth coating layer 3d were visually measured based on the enlarged image.

However, such a conventional measuring method has a problem that it is not efficient because it requires a complicated pretreatment and takes a long time for the measurement. Moreover, since the boundary of the coating layer is visually determined and the thickness of the coating layer is measured, the measurement error is large and the measurement cannot be performed with high accuracy. Also,
There is a problem that the reliability of the measurement result is low because the variation among the measurers is large.

The present invention solves the above-mentioned problems in the conventional method, and the coating layer thickness in the coated fuel particles used for, for example, HTR (high temperature gas reactor) and HTTR (high temperature engineering test research reactor) can be easily adjusted. An object of the present invention is to provide a method for measuring the coating layer thickness in coated fuel particles and a measuring apparatus therefor, which can be automatically measured with high efficiency and high accuracy in operation.

[0005]

In order to solve the above-mentioned problems, the invention according to the above-mentioned claim 1 is directed to coating fuel particles with X
The X-ray photographed image is radiographed, the obtained X-ray photographed image is converted into an electric signal representing the light and shade, the inflection point of the light and shade level in the X-ray photographed image is calculated based on the electric signal, and the covering is performed based on the distance between the inflection points A method for measuring a coating layer thickness in a coated fuel particle, which comprises calculating a layer thickness, wherein the invention according to claim 2 is an X-ray obtained by radiographing the coated fuel particle.
An imaging device that converts a radiographic image into an electric signal corresponding to the gray level, a differentiation processing unit that differentiates the gray level in the X-ray imaging image based on the electric signal output from the imaging device, and a detection by the differentiation processing unit And a thickness calculator for calculating the thickness of the coating layer in the coated fuel particles based on the distance between the inflection points thus formed.

[0006]

According to the present invention, an X-ray image obtained by X-raying the coated fuel particles is imaged by the image pickup device, and the image pickup device outputs an electric signal indicating a gray level in the X-ray image. . The electric signal is output to the differentiation processing unit.
The differentiation processing unit detects the inflection point in the change of the gray level based on the electric signal indicating the gray level in the X-ray image. An electric signal indicating the inflection point output from the differentiation processing unit is output to the thickness calculation unit. The thickness calculator calculates the thickness of the coating layer in the coated fuel particles based on the input electric signal indicating the inflection point. The calculated thickness of the coating layer is displayed by, for example, an output device.

[0007]

EXAMPLES Examples of the method for measuring the coating layer thickness in the coated fuel particles according to the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments.

FIG. 1 is a block diagram showing an example of a coated fuel particle thickness measuring apparatus according to the present invention.

As shown in FIG. 1, a coated fuel particle thickness measuring apparatus 10 is an image pickup apparatus for converting an X-ray photographed image 11 obtained by X-ray photographing of coated fuel particles into an electric signal corresponding to the gray level. 12, a differentiation processing unit 13 that differentiates the gray level in the X-ray image 11 based on the electrical signal output from the imaging device, and the coated fuel particles based on the distance between the inflection points detected by the differentiation processing unit 13. In the present invention, which has the thickness calculation unit 14 for calculating the thickness of the coating layer and the output unit 15 for outputting the thickness of the coating layer calculated by the thickness calculation unit 14, the imaging device 12 uses the coating fuel particles as X-rays. As long as the X-ray image obtained by photographing can be converted into an electric signal corresponding to the gray level, it can be configured by combining various known devices. In this embodiment, Figure 5 As shown, the double coated fuel particles 1a
The X-ray photograph obtained by photographing the X-ray photograph of No. 2 by a known method is magnified using a microscope, and a CCD camera for capturing the magnified image obtained is configured. This imaging device 12
As shown in FIG. 5, the electric signal output from
An electric signal 12A corresponding to a gray level along an arbitrary one direction (L in FIG. 5) of the line image is output. This electric signal 12A shows a curve showing the distribution of the blackening degree corresponding to the first coating layer 3a and the second coating layer 3b.

In addition to the apparatus of this embodiment, an X-ray irradiator and an image pickup device are arranged with the coated fuel particles sandwiched therebetween, and the X-rays irradiated from the X-ray irradiator and transmitted through the coated fuel particles are as they are. A configuration may be adopted in which the image is taken into the image pickup tube, converted into an electric signal and output.

The differential processing section 13 includes the image pickup device 12
The electric signal 12A corresponding to the gray level output from is input, and the curve indicated by the electric signal 12A is subjected to the differential operation processing to obtain the differential curve 12B in FIG. At this time, peaks a ′ and a ″ indicating the existence of the boundary surface a between the fuel core 2 and the first coating layer 3a, and a peak b indicating the existence of the boundary surface b between the first coating layer 3a and the second coating layer 3b. 'And b',
Also, a differential curve having peaks c ′ and c ″ indicating the existence of the boundary surface c of the second coating layer 3b which is the surface of the double coated fuel particle 1a is obtained. The electric signal corresponding to this differential curve is the thickness calculation. It is output to the unit 14.

The thickness calculation unit 14 calculates the difference between the peaks adjacent to each other among the peaks obtained by the differential processing unit 13,
Specifically, the number of pixels between a ′ and b ′, between a ″ and b ″, between b ′ and c ′, and between b ″ and c ″ is calculated. At this time, for example, if 10 pixels are determined to be 1 μm by calibrating in advance and stored in the thickness calculating unit 14, the thickness of the coating layer can be immediately calculated from the calculated number of pixels. Then, the thicknesses of the first coating layer and the second coating layer can be calculated immediately from the number of pixels. The calculated result is displayed on the output unit 15.

The output unit 15 may be a CRT device or a plotter. If you have a storage device,
The calculation result can be saved.

According to the present invention, a series of measurement operations are simple and efficient, and the thickness of the coating layer in the coated fuel particles is measured by an analyzing means such as a personal computer. It is possible to measure with high accuracy because there are few problems and the standard deviation can be reduced.

The present invention can be implemented with appropriate modifications according to the purpose as follows.

The coated fuel particles are not particularly limited, but ceramics such as silicon carbide and zirconium carbide and carbon (for example, pyrolytic carbon) are usually formed on the surface of the fuel core made of nuclear fuel material such as uranium, thorium and plutonium. )
Coated fuel particles formed by forming a coating layer such as The coated fuel particles are used, for example, for an HTR (high temperature gas reactor) or for an HTTR (high temperature engineering test reactor).

The average particle size of the coated fuel particles is usually 80.
The average particle diameter of the fuel core is usually 400 to 600 μm, and the thickness of the coating layer is usually 150 to 250 μm.

The number of coating layers in the above-mentioned coated fuel particles is not particularly limited and may be either a single number or a plurality, but in the case of a plurality, it is usually 2 layers or 4 layers. Examples of the coated fuel particles in which the coated layer is composed of a plurality of layers include, for example, BISO.
Type, TRISO type and the like.

(Experimental Example) The thickness of the coating layer was measured by the method of the present invention and the conventional method of visual observation using a projector and the method of the present invention, and the results are shown in Table 1.
In Table 1, the average thickness is the average of 100 measurements, and the standard deviation is n = 100. In the method of the present invention, the X-ray image
A microscope (Olympus Corp .; BHSM type), a CCD camera (Dag) is used as an image processing means using the image of the line photograph.
e Co., Ltd .; CCD-72E type) and monitor device (S
ONY Co., Ltd .; CPD-1304 type) was used. In the conventional method, a projector (manufactured by Nikon Corporation;
V-12 type) was used.

As a result, according to the method of the present invention,
The standard deviation was smaller than that of the conventional method, and it was possible to measure with high accuracy.

[0021]

[Table 1]

[0022]

[Effect] According to the present invention, for example, the coating layer thickness in the coated fuel particles used for HTR (high temperature gas reactor) and HTTR (high temperature engineering test research reactor) can be automatically adjusted with a simple operation efficiently and with high accuracy. It is possible to provide a coating layer thickness measuring method and a coating layer thickness measuring device for coating fuel particles that can be measured selectively.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a coating layer thickness measuring device as an example for carrying out the method for measuring the coating layer thickness in coated fuel particles according to the present invention.

FIG. 2 is a schematic cross-sectional explanatory view showing an example of a conventional gold phase sample.

FIG. 3 shows a gold phase sample prepared by embedding double-coated fuel particles in a resin and then polishing the double-coated fuel particles to the equatorial plane of the double-coated fuel particles using a polishing machine or the like. It is a schematic cross-sectional explanatory view showing.

FIG. 4 is a schematic cross-sectional explanatory view showing an example of a conventional gold phase sample.

FIG. 5 is an explanatory diagram showing the principle of measuring the thickness of the coating layer according to the present invention.

[Explanation of sign]

1a ... Double coated fuel particles, 1b ... Quadruple coated fuel particles, 2 ... Fuel core, 3a ... First coating layer, 3b.
..Second coating layer, 3c ... Third coating layer, 3d ... Fourth coating layer, 4 ... Equatorial plane, 5 ... Resin, 6 ... Metal phase sample, a ... A boundary surface between the fuel core 2 and the first coating layer 3a, a '... A peak indicating the existence of the boundary surface a, a "...
-Peak indicating the existence of boundary surface a, b ... First coating layer 3
The boundary surface between a and the second coating layer 3b, b '... the peak indicating the existence of the boundary surface b, b "... the peak indicating the existence of the boundary surface b, c ... the double coated fuel particle 1a The boundary surface of the second coating layer 3b serving as the surface of c, the peak indicating the existence of the boundary surface c, the peak of the boundary surface c ″, the peak indicating the existence of the boundary surface 10
・ ・ ・ Coated fuel particle thickness measuring device, 11 ... X-ray image, 12 ... Imaging device, 13 ... Differentiation processing unit, 14
... Calculation unit, 15 ... Output unit.

Claims (2)

[Claims] 1. An X-ray obtained by radiography of coated fuel particles
Converting the radiographic image into an electric signal representing the shade, calculating the inflection point of the gray level in the X-ray image based on the electric signal, and calculating the thickness of the coating layer based on the distance between the inflection points. A method for measuring the coating layer thickness in coated fuel particles, comprising: 2. X-ray obtained by radiography of coated fuel particles
An imaging device that converts a radiographic image into an electric signal corresponding to the gray level, a differentiation processing unit that differentiates the gray level in the X-ray imaging image based on the electric signal output from the imaging device, and a detection by the differentiation processing unit And a thickness calculation unit for calculating the thickness of the coating layer in the coated fuel particles based on the distance between the inflection points.