JP3085828B2 - Appearance inspection system for fuel assemblies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting the appearance of a fuel assembly in a nuclear power plant, and more particularly to an apparatus for inspecting the appearance of fuel rods in the fuel assembly.

[0002]

2. Description of the Related Art In a nuclear power plant, generally, various structural members are inspected at regular inspections to ensure power generation so that power can be generated in a healthy state. The fuel assemblies that make up the reactor core are also subject to inspection, and their appearance inspections are indispensable for ensuring soundness at nuclear power plants.

A conventional fuel assembly appearance inspection apparatus is shown in FIG.
As shown in FIG. 1, a used fuel assembly 2 is installed in a pool 1 filled with water, and the fuel assembly 2 is imaged by an underwater television camera 3. The captured image of the underwater television camera 3 is displayed on the monitor television 12 via the control unit 11 of the television camera. Since the fuel assembly 2 is mounted on the rotary table 7, by rotating the fuel assembly 2, the underwater television camera 3 captures an image of each surface of the fuel assembly 2,
It can be displayed on the monitor TV 12.

Further, the underwater television camera 3 is housed in a waterproof case 4 and is mounted on a base 6b which can be raised and lowered along a lifting mast 6a together with an underwater lighting device 5 for illuminating the fuel assembly 2. The base 6b is driven by the elevating device 6 to move up and down. At this time, the cable 8 of the underwater television camera 3 and the underwater lighting device 5 is fed out or wound up by the drum 9.

The position of the underwater television camera 3 on the elevation mast 6a is detected by an elevation position sensor 13 and displayed on a monitor television 12 by a character generator 14 and is currently
You can grasp which part is being inspected. Reference numeral 10 denotes a power supply device.

In the above configuration, the inspector visually raises and lowers the underwater television camera 3 and rotates the fuel assembly 2 on the rotary table 7 while watching the image captured by the underwater television camera 3 on the monitor television 12. inspect. In this case, the first stage fuel rod 30 is displayed on the monitor TV 12.
When the fuel rods of the second stage are completely hidden behind, the fuel rods 30 of the first stage are displayed in white as shown in an enlarged view in FIG. The gap between the bars appears as a dark portion as indicated by hatching for convenience.

When the second-stage fuel rods 31 are visible between the first-stage fuel rods, an image as shown in FIG. As can be seen from FIG.
If the second-stage fuel rods 31 are seen from between the first-stage fuel rods 30, the boundary between the first-stage fuel rods 30 and the second-stage fuel rods 31 becomes clear unless the image is carefully watched. Since the distance between the fuel rods 30 in the first stage cannot be measured accurately because of the inability to observe, a defective portion was often overlooked.

[0008] For this reason, in order to make the inspection image easy to see and to perform the inspection reliably and easily, Japanese Utility Model Publication 3-4640.
In Japanese Patent Publication No. 0, in addition to the underwater lighting device 5 shown in FIG. 11, as shown in FIG.
Light source 1 for illuminating a strip-shaped parallel light beam (slit light) having a width W
An appearance inspection apparatus for a nuclear fuel assembly equipped with the fuel cell 13 is disclosed. In this conventional example, if the installation is performed so as to satisfy the relationship of W / sin θ <P (P is the pitch of the fuel rods), an image is taken due to the difference in the depth direction of the fuel rods 30 in the portion irradiated with the slit light. The position of the slit light in the image changes, and an image with a three-dimensional effect is obtained as shown in FIG. In FIG. 14, reference numeral 114 denotes a focusing lens;
Is a linear lamp, and 116 is a slit.

[0009]

However, according to the technique disclosed in Japanese Utility Model Publication No. 3-46400, a three-dimensional effect is obtained, so that the boundary between the fuel rod 30 of the first stage and the fuel rod 31 of the second stage is formed. Although it can be clearly distinguished and the interval between fuel rods can be accurately inspected, it is necessary to move the slit light source 113 up and down to obtain a three-dimensional effect over the entire field of view because it is a three-dimensional effect by one slit light. In addition, it is impossible to determine whether the fuel assembly has fallen or warped.

Accordingly, an object of the present invention is to provide a fuel assembly appearance inspection apparatus capable of displaying a three-dimensional image over the entire field of view of a color television camera and capable of judging whether the fuel assembly has fallen or warped. To provide.

[0011]

In order to achieve the above-mentioned object, a visual inspection apparatus for a fuel assembly according to the present invention includes a color television camera capable of imaging light of three different wavelengths, and the color television camera. Three color lighting devices that emit light having a wavelength that can be imaged by the color television camera so as to illuminate the inspection target area of the fuel assembly from different angles with respect to the line of sight, and the inspection imaged by the color television camera It has a color monitor television for displaying an image of the target area, and a dimming mechanism capable of controlling the light emission intensity of the three color lighting devices.

[0012]

Each color lighting device irradiates light of a different wavelength to the inspection target area of the fuel assembly from a different direction from the line of sight of the color television camera. The color television camera captures the reflected light that is reflected back from the surface of the inspection target area. At this time, since the direction of the line of sight picked up by the color television camera is constant and the irradiation directions of the three color lighting devices are different, the components of each color of the image generated by the reflected light change depending on the direction of the surface of the inspection target area. .

If the light intensity of any one of the three color illuminating devices is increased by the dimming mechanism, the surface component on the inspection target area facing the color illuminating device on the image to be picked up. Only the emphasis is on. If the image thus captured is visually checked on a color monitor television, the orientation of the surface of the entire inspection target area can be determined.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

FIG. 1 shows the configuration of a fuel assembly appearance inspection apparatus as one embodiment of the present invention. As in the conventional example of FIG. 11, a spent fuel assembly 2 is installed in a pool 1 filled with water, and according to the present invention, the fuel assembly 2 can image light of three different wavelengths according to the present invention. An image is taken by the color television camera 20. The image captured by the color television camera 20 is displayed on the color monitor television 21 via the control unit 11 of the television camera. Since the fuel assembly 2 is mounted on the rotary table 7, by rotating the fuel assembly 2, each surface of the fuel assembly 2 can be imaged by the color television camera 20 and displayed on the color monitor television 21.

Further, the color television camera 20 is housed in the waterproof case 4 and can be moved up and down along the elevating mast 6a together with underwater lighting devices 22a, 22b and 22c to be described later for illuminating the fuel assembly 2. The base 6b is installed on the table 6b and is moved up and down by driving the base 6b by the elevating device 6. At this time, the color television camera 20 and the cable 8 of each underwater lighting device are fed or wound by the drum 9. The position of the color television camera 20 on the lifting mast 6a is detected by the lifting / lowering position sensor 13 and displayed on the monitor television 21 by the character generator 14 so that it is possible to grasp which part is currently being inspected. Reference numeral 10 denotes a power supply device.

The color television camera 2 of this visual inspection device
0 is sensitive to red, green and blue wavelengths as shown in FIG. As is well known in the art, when each of these three wavelengths is imaged at the same intensity, a white image is obtained. Such a color television camera 20 captures an image so that the line of sight is parallel to the fuel assembly 2 to be inspected.

The image signal output from the color television camera 20 is transmitted to the cable 8, the drum 9, the control unit 1
1 is displayed on the color monitor television 21. A first color illuminator 22a that emits red light, a second color illuminator 22b that emits green light, and a third light that emits blue light, corresponding to three wavelengths having the imaging sensitivity of the color television camera 20. The color lighting device 22c is a color television camera 2
On a plane perpendicular to the line of sight of 0, they are installed on the waterproof case 4 at a certain distance from the line of sight at an angle of 120 °.

In the above-described imaging system, suppose that FIG.
As shown in FIG. 7, a sphere 23 having a constant reflectance for each wavelength and exhibiting uniform reflection characteristics is placed as an object, and an image thereof is taken.

In general, when light is radiated from a single light source 113 onto the surface of an object, its reflection characteristic is such as shown in FIG. Does not exist, and there are few specular reflection surfaces that reflect at the same exit angle as the incident angle of light as shown in FIG.
Actually, as shown in FIG. 6, it is known to exhibit a reflection characteristic in which a regular reflection component and a diffuse reflection component are combined.

Therefore, when an image of a sphere 23 as shown in FIG. 3 is picked up by the image pickup system according to the present invention, as shown in FIG.
The surface facing the direction of a is reddish, the surface facing the direction of the green second color lighting device 22b is greenish, and the surface facing the direction of the blue third color lighting device 22c is Each color lighting device 22a is bluish, as shown on the top of a sphere 23,
It has been found that the surface uniformly irradiated from 22b and 22c is imaged white.

From the above, as shown in FIG. 8, the density of each color when the image is picked up depends on the reflection characteristic of the surface of the sphere 23, the irradiation direction of the color illuminators 22a, 22b and 22c, and the color. The imaging direction of the TV camera 20 and the sphere 23
And the direction of the normal to each point on the surface. For this reason, the image of the image pickup area in the middle of each image pickup area is mixed with these colors to become an intermediate color.

The actual fuel assembly 2 is made of metal, and its surface has relatively large regular reflection components in its reflection characteristics.
In addition, since it is close to an achromatic color, it can be said that the difference in reflection characteristics for each wavelength is so small that it can be ignored. Therefore, when the fuel assembly 2 is imaged by the above-described imaging system, as shown in FIG. 9, the front surface of the fuel rod 30 is imaged white, the right side is magenta, and the left side is yellowish. Is done. Further, like the support plate 2a of the fuel rod 30 (see FIG. 1), a slightly upward portion is reddish, and a downward portion is bluish green.

As shown in FIG. 10, when the second-stage fuel rod 31 is visible from the gap between the first-stage fuel rods 30, the end of the first-stage fuel rod 30 has a yellow color as described above. After being tasted, the surface of the second-stage fuel rod 31 becomes white again, so that the boundary between the two fuel rods 30 and 31 can be clearly determined. Since the color lighting devices 22a, 22b and 22c illuminate the entire area of the visual field of the color television camera 20, it is possible to determine whether the fuel assembly 2 has fallen or warped.

When the reflectivity at each wavelength changes as a result of the nuclear fission reaction in the nuclear reactor of the fuel assembly 2, the light intensity of each wavelength is changed by the well-known dimming mechanism 24 to adjust the color. The inspection can be performed in the same manner as described above. Further, even when the undulation of the fuel assembly 2 in a specific direction is inspected, the dimming mechanism 24 allows the illumination devices 22a, 22b, 22
If the light emission intensity of c is individually adjusted, it is possible to easily determine the undulation in that direction.

[0026]

As described above, according to the present invention, a visual inspection operation of a fuel assembly of a nuclear power plant is performed by using only a simple optical device such as a color television camera, a color lighting device, and a dimmer. Inspection of fuel rods can be carried out without being adversely affected by subsequent fuel rods,
Inspection of three-dimensional shapes such as dents and curling of fuel assembly components that are difficult to judge with a two-dimensional image obtained by an underwater television camera can be easily performed. Since a three-dimensional effect can be simultaneously obtained in the entire region, an industrial use effect is extremely large, such as an inspection of a fuel assembly falling or warping.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a fuel assembly appearance inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a view showing the wavelength sensitivity of a color television camera used in the appearance inspection apparatus of FIG. 1;

FIG. 3 is an explanatory diagram of a case where a sphere is imaged by the appearance inspection apparatus of FIG. 1;

FIG. 4 is a general explanatory diagram of a perfect irregular reflection surface.

FIG. 5 is a general explanatory diagram of a regular reflection surface.

FIG. 6 is a diagram illustrating the reflection characteristics of a general object.

FIG. 7 is a view for explaining an image when the sphere shown in FIG. 3 is imaged by the appearance inspection apparatus of FIG. 1;

FIG. 8 is a view for explaining a density change of a sphere image picked up by the appearance inspection apparatus of FIG. 1;

FIG. 9 is a view for explaining an image when the fuel assembly is imaged by the appearance inspection device of FIG. 1;

FIG. 10 is a view for explaining an image when a second-stage fuel rod is visible from a gap between the first-stage fuel rods.

FIG. 11 is a schematic configuration diagram showing a conventional fuel assembly appearance inspection apparatus.

FIG. 12 is a view for explaining an imaging situation of a fuel assembly obtained by the appearance inspection device of FIG. 11;

FIG. 13 is a view for explaining another imaging situation of the fuel assembly obtained by the appearance inspection device of FIG. 11;

FIG. 14 is a view for explaining the configuration of another conventional fuel assembly appearance inspection apparatus.

FIG. 15 is a view for explaining the inspection state of the fuel assembly by the appearance inspection device of FIG. 14;

[Explanation of symbols]

2 ... fuel assembly, 4 ... waterproof case, 20 ... color television camera, 21 ... color monitor television, 22a, 22b,
22c: color lighting device, 24: dimming mechanism, 30: first-stage fuel rod, 31: second-stage fuel rod.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-170705 (JP, A) JP-A-62-38348 (JP, A) Real opening Sho-60-134196 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G21C 17/06 G01B 11/30 G01N 21/88 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A color television camera capable of imaging light of three different wavelengths, and said color television so as to illuminate an inspection target area of a fuel assembly from different angles with respect to the line of sight of the color television camera. Three color illumination devices that emit light having a wavelength that can be imaged by a camera, a color monitor television for displaying an image of the inspection target area captured by the color television camera, and emission intensity of the three color illumination devices. An appearance inspection device for a fuel assembly having a dimming mechanism that can be controlled.