CA2488318C - Dimensional measurement and inspection system of candu fuel bundle in-bay of candu power plant - Google Patents

Abstract

Provided is a dimensional measurement and inspection system of a CANDU nuclear fuel bundle in a water chamber (reception bay) of a Heavy water nuclear reactor. In the system, a dimension measuring unit measures a dimension (i.e., surface profile of fuel rod, diameter and length of fuel bundle, end plate waviness of fuel bundle, circumferential profile of fuel bundle) of the nuclear fuel bundle by using a plurality of linear variable measurement sensors (LVDT) . An inspecting unit inspects a surface of the nuclear fuel bundle through a radiation tolerant camera. A control unit automatically processes a variety of data and image data, which are provided from the dimension measuring unit and the inspecting unit, by using a control computer. The system accurately measures and inspects the nuclear fuel bundle in air or water to output its resultant values.

Description

DIMENSIONAL MEASUREMENT AND INSPECTION SYSTEM OF
CANDU FUEL BUNDLE IN-BAY OF CANDU POWER PLANT
BACKGROUND OF THE INVENITON

Field of the Invention The present invention relates to a system of accurately measuring a dimension of a nuclear fuel bundle and inspecting an exterior of a nuclear fuel rod, and more particularly, to a dimensional measurement and inspection system of a nuclear fuel bundle in a water chamber (Reception bay) of a CANDU power plant by which the nuclear fuel bundle is accurately measured using linear variable measurement sensors (LVDTs: Linear Variable Differential Transformers) in dimension in air or water and is inspected using a radiation tolerant camera on its surface in water to evaluate an integrity of the nuclear fuel bundle loaded and irradiated in a channel, and by which measured data is utilized for the development of a new nuclear fuel to improve safety of a heavy water reactor.

Description of the Related Art Generally, electric power plants for generating power are classified into a hydroelectric power plant, a thermal power plant, a nuclear power plant and the like depending on used power sources. As one example of a nuclear reactor used in the nuclear power plant, there is a heavy water nuclear reactor (CANDU) (Hereinafter, referred to as "heavy water reactor").

As shown in Figs. 11A and 11B, a nuclear fuel bundle 300 loaded in the heavy water reactor includes a nuclear fuel bundle having 37-element fuel rods (Hereinafter, referred to as "37-rod nuclear fuel bundle") or a CANDU FLEXible fueling (CANFLEX) fuel bundle having 43-element fuel rods (Hereinafter, referred to as "CANFLEX nuclear fuel bundle").
Each of the nuclear fuel bundles has a structure of one center rod, six or seven inner-ring rods, twelve or fourteen intermediate-ring rods, and eighteen or twenty-one outer-ring rods. As shown in FIGS. 11A and 11B, the nuclear fuel bundle 300 has a plurality of nuclear fuel rods 310 fixed in parallel and side by side. At upper and lower ends of the nuclear fuel bundle 300, an end plate 314 and the nuclear fuel rods 310 of each ring are fixedly welded. A spacer (not shown) is disposed at a middle of the nuclear fuel bundle 300. If the heavy water nuclear fuel bundle is loaded and irradiated in a nuclear fuel channel, which is in an environment of high temperature, high pressure and high radiation, it may be deformed. Since such deformation may influence an entirety of the nuclear fuel bundle 300 and the nuclear fuel channel (not shown) , accurate measurement and inspection of a dimension are required.

In other words, a variety of data obtained through the measurement and inspection can be utilized for entirety evaluation of the nuclear fuel bundle 300 loaded and irradiated in the nuclear fuel channel of the Heavy water reactor.

However, since an automized apparatus or system for accurately and precisely measuring or inspecting the dimension of the nuclear fuel bundle 300 in the air or in a water chamber of the heavy water reactor does not exist, there is a drawback in that the dimension of the nuclear fuel bundle loaded and irradiated in the nuclear fuel channel of the heavy water reactor cannot be confirmed.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been devised to solve the aforementioned problems.

An object of the present invention is to provide a dimensional measurement and inspection system of a nuclear fuel bundle in a water chamber of a power plant by which a nuclear fuel bundle loaded and irradiated in a nuclear fuel channel can be accurately measured in dimension in air or water and can be inspected using a radiation tolerant camera on its surface in water to evaluate an integrity of the nuclear fuel bundle.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a dimensional measurement and inspection system of a nuclear fuel bundle in air or water chamber (reception bay) of a heavy water nuclear reactor, the system comprising: a dimension measuring unit for measuring a dimension of the nuclear fuel bundle; an inspecting unit for moving in the lengthwise direction of the nuclear fuel bundle, and for inspecting a surface of the nuclear fuel bundle through a radiation tolerant camera; and a control unit for automatically processing a variety of data and image data, which are provided from the dimension measuring unit and the inspecting unit, by using a control computer, wherein the dimension measuring unit further comprises:

a rotary unit disposed at a side position of the inspecting unit, and rotating the nuclear fuel bundle which is put on the rotary unit;

a length and profile measuring unit disposed at a position adjacent to two ends of the rotary unit, and measuring a length of the nuclear fuel bundle and a profile of end plates of the nuclear fuel bundle which is rotated on the rotary unit by using a plurality of linear variable measurement sensors (LVDT); and a diameter and profile measuring unit moving in the lengthwise direction of the nuclear fuel bundle, and measuring a diameter and an outward surface profile of the nuclear fuel bundle;

whereby the nuclear fuel bundle is accurately measured and inspected in air or water to output its resultant values.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention.
In the drawings:

FIG. 1 is a view illustrating a whole construction of a dimensional measurement and inspection system of a nuclear fuel bundle in a water chamber of a heavy water reactor according to the present invention;

FIG. 2 is a perspective view illustrating a dimension measuring unit and an inspecting unit of a dimensional j ., 4a nuclear fuel bundle in a water chamber of a heavy water reactor according to the present invention;

FIG. 4 is a sectional view illustrating a motor of a rotary unit of a dimension measuring unit of FIG. 3;

FIG. 5 is a sectional view illustrating a rotary cylinder of a position adjusting unit of a dimension measuring unit of FIG. 3;

FIGS. 6A and 6B respectively are a sectional view and a side view illustrating a rotary motor of a length and profile measuring unit of a dimension measuring unit of FIG. 3;

FIGS. 7A, 7B and 7C respectively are a crosssectional view, a lengthwise side view and a plane sectional view illustrating a diameter and profile measuring unit of a dimension measuring unit of FIG. 3;

FIGS. 8A and 8B respectively are sectional views illustrating a left mount and a right mount of a diameter and profile measuring unit of FIG. 7;

FIGS. 9A, 9B and 9C respectively are a plane view, a crosssectional view and a side sectional view illustrating an inspecting unit of FIG. 3;

FIGS. 10A and 10B respectively are a side view and a rear side view illustrating a mirror of an inspecting unit of FIG. 3; and FIGS. 11A and 11B respectively are an exterior perspective view and a horizontal sectional view illustrating a CANDU nuclear fuel bundle according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

FIG. 1 is a view illustrating a whole construction of a dimensional measurement and inspection system of a nuclear fuel bundle in a water chamber of a heavy water reactor.
As shown in FIG. 1, the dimensional measurement and inspection system 1 includes a dimension measuring unit 10 for measuring a variety of dimensions of a nuclear fuel bundle 300; an inspecting unit 150 for remotely photographing and inspecting a surface of the nuclear fuel bundle 300; and a control unit 200 for processing and outputting a variety of data such as image data provided from the dimension measuring unit 10 and the inspecting unit 150.
The dimension measuring unit 10 is positioned on a predetermined sized support plate 12. As shown in FIG. 2 and FIGS. 3A, 3B and 3C, overturned U-shaped frames 14 are protruded from both corners to an upper side of the support plate 12. A hook frame 16 is provided at a center of the overturned U-shaped frame 14 to hang on a hook of a crane (not shown). Accordingly, due to an operation of the crane, the support plate 12 can be immersed up to a depth of about 10m in a water chamber (W) of a heavy water reactor shown in FIG. 1, or lifted and moved out of the water chamber X.

The dimension measuring unit 10 mounted on the support plate 12 includes a rotary unit 20 for rotating the nuclear fuel bundle 300 putted at one side of the support plate 1.2.

The rotary unit 20 includes a rotary motor 22 of FIG. 4 on the support plate 12. A driving pulley 24 is mounted at a shaft 22a of the rotary motor 22. Further, the rotary unit 20 includes an endless track-type first belt 26a loaded on the driving pulley 24 and a plurality of first driven pulleys 28a loaded and rotated on the first belt 26a.
Additionally, the first driven pulleys 28a are disposed at the one ends of a plurality of rotary shafts 30 extending in a length direction of the rotary motor 22. The rotary shafts 30 are rotatably disposed through support brackets 32a and 32b, which are disposed at front and rear sides of the rotary motor 22. Second driven pulleys 28b corresponding to the first driven pulleys 28a are respectively connected to the other ends of the rotary shafts 30. A third driven pulley 28c is disposed under the second driven pulley 28b to be loaded on the second belt 26b loaded on the second driven pulley 28b.
The third driven pulley 28c is positioned at an opposite side of the driving pulley 24 centering on the rotary motor 22. Further, the third driven pulley 28c is rotatably connected to the rear support bracket 32b.
Accordingly, if the driving pulley 24 is rotated due to the operation of the rotary motor 22, the first belts 26a allow the rotation of the first driven pulleys 28a. The first driven pulleys 28a rotate the second driven pulleys 28b by using the plurality of rotary shafts 30. The second driven pulleys 28b rotate the third driven pulleys 28c by using the second belt 26b in the form of an endless track.

The rotary unit 20 is disposed to hang left and right sides of the nuclear fuel bundle 300 on the first belt 26a and the second belt 26b when the nuclear fuel bundle 300 is putted on the first belt 26a and the second belt 26b as shown in FIG. 3B. In this state, the first and second belts 26a and 26b are rotated due to the operation of the rotary motor 22. Accordingly, the nuclear fuel bundle is rotated on the first and second belts 26a and 26b.

Additionally, a position adjusting unit 40 is provided at the rotary unit 20 to adjust left and right positions of the nuclear fuel bundle, which is putted on the first and second belts 26a and 26b in proximal to the rotary unit 20.
The position adjusting unit 40 is comprised of a plurality of rotary cylinders 42 disposed at left and right sides of and in parallel with the motor 22 of the rotary unit 20 as shown in FIGS. 3B and 5. The rotary cylinders 42 are fixed to the support brackets 32a and 32b, to which the rotary shafts 30 are fixed, by using a fixing part 42a and bolts. A pusher block 46 is disposed at an end of a rod of the rotary cylinder 42.

A plurality of rollers 48 are rotatably disposed at the pusher block 46 to provide a pushing force without damaging an end plate of the nuclear fuel bundle 300.
In other words, where the nuclear fuel bundle 300 is putted on the first and second belts 26a and 26b of the rotary unit, the position adjusting unit 40 accurately adjusts the left and right positions of the nuclear fuel bundle 300. The left and right movement of the nuclear fuel bundle 300 is performed by activating the rotary cylinder 42 during the rotation of the nuclear fuel bundle using the rotary motor 22 such that the nuclear fuel bundle 300 can be adjusted in the lengthwise direction at the same time of the rotation of the nuclear fuel bundle 300.

For this, at a position adjustment operation of the nuclear fuel bundle 300, the left and right rotary cylinders 42 are firstly operated in a long extended state of the rod 44 to rotate the pusher block 46, which is connected to the rod 44, from a downward state shown using a solid line to an upward state shown using a dotted line of FIG. 5. Then, the rod 44 is activated and gradually puled toward a cylinder body such that the plurality of rollers 48 provided at the pusher block 46 are adhered to an end of the nuclear fuel bundle 300, which is being rotated, to pull the nuclear fuel bundle 300 and to adjust the position of the nuclear fuel bundle 300 on the first and second belts 26a and 26b. The reason why the nuclear fuel bundle 300 is lengthwise moved while being rotated on the first and second belts 26a and 26b is to minimize a local abrasion during the movement of the nuclear fuel bundle 300.
Additionally, the dimension measuring unit 10 includes a length and profile measuring unit 50 for measuring the length of the nuclear fuel bundle 300 at left and right sides of the rotary unit 20 at which the nuclear fuel bundle 300 is positioned and rotated, and measuring profile of the nuclear fuel bundle's boss end plates 314.

The length and profile measuring unit 50 includes a plurality of linear variable measurement sensors (LVDT) 52 each coaxially disposed at left and right sides to interpose the rotary motor 22 therebetween; double-acting pneumatic cylinders 54 for moving the linear variable measurement sensors 52 to the left and right in an axial direction of the nuclear fuel bundle 300 on the rotary unit 20; and rotating motors 56 for rotating the linear variable measurement sensors 52 in a circumferential direction of the nuclear fuel bundle 300.

In other words, the linear variable measurement sensors 52 are fixed in a row on a holder 58 as shown in FIGS. 6A
and 6B. An array interval of the linear variable measurement sensors 52 corresponds to a center of each ring of the nuclear fuel bundle 300. That is, the lowest-positioned linear variable measurement sensor 52 corresponds to a center of the nuclear fuel bundle 300 and a center of the rotating motor 56, and upper linear variable measurement sensors 52 are linearly disposed and fixed toward an exterior (radius) of the nuclear fuel bundle 300.
Accordingly, when the linear variable measurement sensors 52 is rotated once, the above-arrayed linear variable measurement sensors 52 turn once around an end plate 314 provided at end sides of the nuclear fuel bundle 300 as shown in FIG. 3B.

The length and profile measuring unit 50 includes the rotating motors 56 at the left and right sides of the nuclear fuel bundle 300 to provide a rotary force for allowing the linear variable measurement sensors 52 to turn once around the end plate 314 of the nuclear fuel bundle 300. A rotary shaft of the rotating motor 56 is connected to a rear end of the holder 58 at which the linear variable measurement sensors 52 are mounted in a row.
Additionally, the rotating motor 56 is connected to a moving member 54a of the double-acting pneumatic cylinder 54 through its lower support 56a. That is, the double-acting pneumatic cylinder 54 includes the moving member 54a movably fitted to a guide 54c provided on a slide base 54b. The moving member 54a can be moved to the left and right along the guide 54c by a pneumatic air applied to the double-acting pneumatic cylinder 54.

Resultantly, the plurality of linear variable measurement sensors 52 arranged in a row can be rotated in a circumferential direction of the nuclear fuel bundle 300 by the rotating motor 56, and can be moved in the lengthwise direction of the nuclear fuel bundle 300 by the double-acting pneumatic cylinders 54.

In case that the length and profile measuring unit 50 measures the length of the nuclear fuel bundle 300, the double-acting pneumatic cylinders 54 are operated facing to each other at the left and right sides of the nuclear fuel bundle 300 to move the linear variable measurement sensors 52 toward the end plates 314 disposed at the left and right sides of the nuclear fuel bundle 300. In this state, if touch rods 52a of the linear variable measurement sensors 52 are in contact with the end plate 314, the linear variable measurement sensors 52 respectively transmit different voltage values to a control unit 200 (described later) depending on a pressed degree (intensity) of the touch rods 52a. The control unit 200 calculates a variation of a moving distance of a corresponding linear variable measurement sensor 52 on the basis of the outputted voltage value, and as a result, measures the length of the nuclear fuel bundle 300 by using the variation of the moving distance of the left and right linear variable measurement sensors 52 facing each other.
Additionally, if the rotating motor 56 is activated in a state where the touch rods 52a of the linear variable measurement sensors 52 are in contact with the end plate 314, the linear variable measurement sensors 52 rotate in the circumferential direction of and in contact with the end plate 314. During the rotation, the linear variable measurement sensors 52 sequentially transmit the different outputted voltage values depending on the profile of the nuclear fuel bundle 300. Accordingly, the control unit 200 can reproduce, detect and output the profile of the corresponding nuclear fuel bundle 300 on the basis of the outputted values.

Additionally, the dimension measuring unit 10 includes a diameter and profile measuring unit 70 for measuring the diameter of the nuclear fuel bundle 300 having an approximate circular shape and the profile of the nuclear fuel rod 310.

As shown in FIGS. 7A, 7B and 7C, the diameter and profile measuring unit 70 includes a pair of linear variable measurement sensors 72 disposed to horizontally face each other at front and rear sides of the nuclear fuel bundle 300;
an overturned U-shaped fixing member 74 for allowing the linear variable measurement sensors 72 to be disposed at front and rear sides of the nuclear fuel bundle 300; and a transfer motor 76 for moving the fixing member 74 in the lengthwise direction of the nuclear fuel bundle 300.

Additionally, the diameter and profile measuring unit 70 includes guide rails 78 fixed to the support plate 12 in parallel with each other at a lower and lateral side of the nuclear fuel bundle 300 to guide the fixing member 74 in the lengthwise direction of the nuclear fuel bundle 300. A ball screw 80 is rotatably disposed at a center of the guide rail 78 to be connected to a rotary shaft of the transfer motor 76, thereby allowing a forward or reverse rotation.
Further, the ball screw 80 is screwed into a moving block 82 connected to the fixing member 74 such that the forward or reverse rotation of the transfer motor 76 allows the moving block 82 and the fixing member 74 to be moved to the left and right along the guide rail 78 through the rotation of the ball screw 80.
The diameter and profile measuring unit 70 measures the diameter of the nuclear fuel bundle 300 and the outward surface profile of the nuclear fuel rod 310 positioned at a side of an outer diameter of the nuclear fuel bundle 300. The transfer motor 76 allows the overturned U-shaped fixing member 74 to be initially positioned at a home position deviated from one side of the nuclear fuel bundle 300 putted on the rotary unit 20. However, if the transfer motor 76 is operated, the ball screw 80 is rotated. Accordingly, the ball screw 80 allows the overturned U-shaped fixing member 74 to be moved and stopped at a predetermined position of the one end of the nuclear fuel bundle 300.
In this state, if the front and rear pneumatic cylinders 72b are activated to move the linear variable measurement sensors 72 toward the nuclear fuel bundle 300, an end of the touch rod 72a has its front and rear strokes of about 5mm, thereby causing a contact with surfaces of the nuclear fuel rods 310, which correspond to the diameter of the nuclear fuel bundle 300, as shown in FIG. 7A.

Additionally, if the linear variable measurement sensors 72 contact the nuclear fuel bundle 300 to output the voltage values, the control unit 200 converts the voltage values into the diameter of the nuclear fuel bundle 300. The transfer motor 76 is additionally operated to allow the linear variable measurement sensors 72 to be moved in the lengthwise direction of the nuclear fuel bundle 300. In other words, the linear variable measurement sensors 72 are moved from one end to the other end of the nuclear fuel bundle 300 for a continuous measurement.
Additionally, if the linear variable measurement sensors 72 are moved in the lengthwise direction of the nuclear fuel bundle 300 while detecting the voltage values, the voltage values are sequentially outputted to measure the diameter from one end to the other end of the corresponding nuclear fuel bundle 300. The control unit converts the detected voltage values into distance values to measure the lengthwise profile of the nuclear fuel rods 310 in contact with the linear variable measurement sensors 72.

Meanwhile, the diameter and profile measuring unit 70 performs the measurement, not only one time, but a plurality of times for each of a plurality of nuclear fuel rods 310 disposed at the exterior of the nuclear fuel bundle 300. For this, the nuclear fuel bundle 300 should be rotated on the rotary unit 20 by a predetermined angle.
In this case, the nuclear fuel rods 310 should be disposed on the rotary unit 20 such that the linear variable measurement sensors 72 of the diameter and profile measuring unit 70 detect maximal outer diameters of the nuclear fuel rods 310. At this time, as shown in FIGS. 1 and 3B, a reference setting sensor 90 is disposed at one side of the rotary unit 20 to set a reference for the disposition. The reference setting sensor 90 is comprised of Linear Variable Differential Transformers (LVDTs) in the same manner as the linear variable measurement sensors 52 and 72. An interval between the reference setting sensor 90 and the linear variable measurement sensors 72 corresponds to an interval between the maximal outer diameters of the nuclear fuel rods 310 respectively contacting the sensors 72 and 90.
Accordingly, if the sensor 90 detects the maximal outer diameter of the corresponding nuclear fuel rod 310 by allowing a touch rod 90a to be in contact with any one nuclear fuel rod 310 of the nuclear fuel bundle 300 at a predetermined point, the linear variable measurement sensors 72 are disposed respectively corresponding to the maximal outer diameters of the nuclear fuel rods 310 contacting the linear variable measurement sensors 72. This state is a reference for rotation.

As such, the position of the reference setting sensor 90 functions as a reference point for allowing the linear variable measurement sensors 72 provided at the diameter and profile measuring unit 70 to exactly measure the diameter of the nuclear fuel bundle 300. Accordingly, the position of the reference setting sensor 90 is of importance.
Alternatively, in the above set state of the reference point, the rotary motor 22 is rotated at a predetermined angle depending on whether the nuclear fuel bundle 300 is a 37-rod nuclear fuel bundle or a CANFLEX nuclear fuel bundle.
The nuclear fuel bundle 300 rotated at the predetermined angle is newly detected in diameter by contacting new nuclear fuel rods 310 with the linear variable measurement sensors 72.

The diameter and profile measuring unit 70 interacts with the rotary unit 20 and the reference setting sensors 90 to measure all of the diameters of the nuclear fuel rods 310 disposed at the exterior of the 37-rod nuclear fuel bundle or the CANFLEX nuclear fuel bundle and concurrently to measure all of lengthwise profiles of eighteen or twenty-one nuclear fuel rods 310.
Meanwhile, the overturned U-shaped fixing member 74 has front and rear sensor mounts 88a and 88b having different structures as shown in FIGS. 8A and 8B to face the linear variable measurement sensors 72 with each other in the diameter and profile measuring unit 70.

In other words, the front sensor mount 88a has a vertical line structure for horizontally mounting the linear variable measurement sensor 72, but the rear sensor mount 88b has a tilt portion (S) at its middle side and has a line portion (Sa) at its lower side to allow the linear variable measurement sensor 72 to be selectively mounted at a different tilt angle according to need.
This is because where different numbers of the nuclear fuel rods 310 such as 37 or 43 nuclear fuel rods are to be measured, the linear variable measurement sensors 72 should be different in position depending on different disposition angles of the nuclear fuel rods 310 in circumferential directions of the nuclear fuel bundle 300.

In other words, in case that the nuclear fuel bundle 300 has 37 nuclear fuel rods 310, 18 nuclear fuel rods 310 are disposed at the exterior of the nuclear fuel bundle 300 to form nine pairs such that the nuclear fuel bundle 300 can be maintained at a constant angle in the circumferential direction and accordingly the linear variable measurement sensor 72 can be horizontally disposed.
However, where the nuclear fuel bundle 300 has 43 nuclear fuel rods 310, 21 nuclear fuel rods 310 are disposed at the exterior of the nuclear fuel bundle 300. Therefore, some of the nuclear fuel rods 310 form pairs. Accordingly, when the linear variable measurement sensors 72 are horizontally disposed, they cannot accurately measure the diameter and profile of the nuclear fuel bundle 300.
As such, if the nuclear fuel bundle 300 has 37 nuclear fuel rods 310, the linear variable measurement sensors 72 of the front and rear sensor mounts 88a and 88b are horizontally mounted to face each other for the measurement. However, if the nuclear fuel bundle 300 has 43 nuclear fuel rods 310, the linear variable measurement sensor 72 of the front sensor mount 88a is horizontally mounted and the linear variable measurement sensor 72 of the rear sensor mount 88b is aslant mounted on the tilt portion (S) as shown in a dotted line such that 21 outer nuclear fuel rods should be disposed to correspond to the interval formed in the circumferential direction of the nuclear fuel rod 310.

By doing so, the diameter of the nuclear fuel bundle 300 and the lengthwise profiles of the nuclear fuel rods 300 can be measured.

Additionally, the inventive dimensional measurement and inspection system 1 includes the inspecting unit 150 for inspecting the surface of the nuclear fuel bundle 300 by using a radiation tolerant camera 155.

The radiation tolerant camera 155 of the inspecting unit 150 is mounted to remotely confirm as to whether or not the nuclear fuel bundle 300 is damaged within the water chamber (W) of the Heavy water reactor. The inspecting unit 150 also includes a driving unit for moving the radiation tolerant camera 155.

The inspecting unit 150 includes a pair of first shaft rails 157 for moving the camera 155 in the lengthwise direction of the nuclear fuel bundle 300; a ball screw 159 disposed between the first shaft rails 157; and the first driving motor 160 for forward and reverse rotations of the ball screw 159. That is, the ball screw 159 has one end connected to a rotary shaft 160a of the first driving motor 160. A left and right moving block 164 combined to run on the fist shaft rails 157 is screwed into the ball screw 159 to be horizontally moved to the left and right by the operation of the first driving motor 160.
Additionally, a second shaft rail 166 is disposed in a vertical direction of the first shaft rail 157 on an upper surface of the left and right moving block 164. A front and rear moving block 170 combined to run and move in a lengthwise direction of the second shaft rail 166 is disposed at the second shaft rail 166. The front and rear moving block 170 includes roller pairs 168 horizontally disposed to encompass and rotate at left and right sides of the second shaft rail 166 to be combined with the second shaft rail 166 of the left and right moving block 164. Further, as shown in FIG. 9, a second driving motor 174 is provided as a driving source at one side of the front and rear moving block 170. A
pinion gear 176 is provided at a rotary shaft of the second driving motor 174. The pinion gear 176 is geared into a fixed rack gear 178 along the second shaft rail 166 at one side of the left and right moving block 164.

Accordingly, when the second driving motor 174 is operated, the pinion gears 176 are rotated on the rack gear 178 to allow a front and rear movement. Resultantly, the rollers 168 of the front and rear moving block 170 are run and moved on the second shaft rail 166 of the left and right moving block 164.

Through the above driving mechanism, the radiation tolerant camera 155 mounted on the front and rear moving block 170 can access the nuclear fuel bundle in the lengthwise direction of the nuclear fuel bundle 300 along the first shaft rail 157 by the operation of the first driving motor 160, and in a diameter (radius) direction of the nuclear fuel bundle 300 along the second shaft rail 166 by the operation of the second driving motor 174.

Meanwhile, the radiation tolerant camera 155 remotely adjusts an angle of a built-in lens (now shown) to perform a lens tilting function for allowing a self-photograph using a lens barrel.

Accordingly, the inspecting unit 150 can perform an accurate remote image inspection of the nuclear fuel bundle 300 since the radiation tolerant camera 155 can move along the lengthwise direction or diameter direction of the nuclear fuel bundle 300 for close-up photographing of the nuclear fuel bundle 300, and can photograph at various angles by using the tilting function.

Additionally, the inspecting unit 150 includes a plurality of mirrors 180 at an opposite side of the nuclear fuel bundle 300, that is, at an opposite side of the camera 155, to prevent a generation of a blind spot at which the camera 155 cannot photograph such that an end plate 314 portion, which cannot be directly photographed by the camera 155, is indirectly photographed.
The mirrors 180 are provided at both sides of the nuclear fuel bundle 300 in FIG. 3, and are constructed to mirror the end plate 314, which is not photographed by the camera 155. Further, the mirror 180 includes an angle adjustment plate 182 for adjusting a mount angle to allow a surface of the mirror 180 to be slanted up and down as shown in FIG. 10.

The inspecting unit 150 includes a post 184 vertically disposed; a plurality of joint screws 186 screwed into the post 184; the angle adjustment plate 182 fixed at one side of the post 184 by the joint screws 186; and the mirror 180 fixed at a front side of the angle adjustment plate 182.

Additionally, the angle adjustment plate 182 is constructed to respectively have a plurality of circular arcs 182a for the joint screws 186, thereby maintaining an interval corresponding to an interval between the joint screws 186, and allowing the joint screws 186 to pass through the circular arcs 182a.
Accordingly, by adjusting the positions of the circular arcs 182a, a tilt angle at which the mirror is mounted can be adjusted, and the angle can be optimally selected to set the camera 155.

Further, the inventive dimensional measurement and inspection system 1 includes the control unit 200 for processing a variety of data and image data provided from the inspecting unit 150 by using a control computer 210 to output its result value.

As shown in FIG. 1, the control unit 200 includes a sensor controller 212 electrically connected to each of the sensors 52, 72 and 90 to control operations of the sensors 52, 72 and 90, and to receive and process a signal from the sensors 52, 72 and 90; a motor controller 214 for controlling the motors 22, 56, 76, 160 and 174 and the double-acting pneumatic cylinders 54 to move the linear variable measurement sensors 52 and 72 at desired positions; and a data processing unit 216 for processing data measured by each of the sensors 52, 72 and 90.

Additionally, the control unit 200 includes a control computer 210 connected to the control units 212, 214 and 216 to process a variety of data, perform a necessary operation, and control a variety of the sensors 52, 72 and 90 and the motors 22, 56, 76, 160 and 174 depending on a preset program.
In addition, the control unit 200 includes a display unit 230 having a control monitor and an inspection image monitor (Television) 232. The control monitor 234 provides and outputs the processed detected values and measured values, and displays a control state to external workers.
The inspection image monitor 232 displays the image of the radiation tolerant camera of the inspecting unit. The control unit 200 can additionally include an image recorder 240, a personal computer 242 and the like to move and store a variety of measured values and inspection images.
For operation in atmosphere or water, the inventive dimensional measurement and inspection system 1 has a watertight structure of a variety of important parts such as sensors 52, 72 and 90, the motors 22, 56, 76, 160 and 174, the cylinder 54 and the camera 155 to be injected into the water chamber (W) of the heavy water reactor.

In case that the dimensional measurement and inspection system 1 works in water, the dimension measuring unit 10 and the inspecting units 150 putted on the support plate 12 are hoisted using a hook of a crane (not shown), and then can be injected and slowly immersed up to a depth of about 10 m of the water chamber (W) of the heavy water reactor.

Additionally, a variety of power sources, signals, pneumatic supply lines (K) and the like are drawn from the immersed dimension measuring unit 10 and inspecting unit 150 to the external of the water chamber (W) . The automatic control unit 200, which is connected to the power sources, signals, pneumatic supply lines (K), is adjusted by the worker at the external of the water chamber M.

In order to measure and inspect the nuclear fuel bundle 300 by using the immersed dimension measuring unit 10 and the inspecting units 150 as described above, the corresponding nuclear fuel bundle 300 should be putted on the rotary unit 20.

In this case, the nuclear fuel bundle 300 to be measured and inspected is picked-up, moved and putted on the first and second belts 26a and 26b of the rotary unit 20 by using a separate handling unit (not shown) for the nuclear fuel bundle.
Since the handling unit can employ a conventional handling unit for stably moving the nuclear fuel bundle 300 without impact, a detailed description thereof is omitted.
As such, the present invention can accurately measure a variety of dimensions and detect the profile of the nuclear fuel bundle 300 putted on the rotary unit 20, and determine whether or not the nuclear fuel bundle 300 is damaged at its exterior surface.

Length measurement of nuclear fuel bundle and Profile measurement of nuclear fuel bundle For this, the present invention allows the nuclear fuel bundle 300 putted on the first and second belts 26a and 26b of the rotary unit 20 to be rotated owing to the driving of the rotary motor 22. The rotary motor 22 is used to rotate the plurality of driven pulleys 28a, 28b and 28c together with the first and second belts 26a and 26b while rotating the nuclear fuel bundle 300 on the first and second belts 26a and 26b.

Additionally, the position adjusting unit 40 is activated to move the nuclear fuel bundle 300 at a predetermined position. In a state where the rods 44 of the rotary cylinders 42 are long extended, the position adjusting unit 40 is activated to rotate the pusher block 46 from the downward state shown using the solid line of FIG. 5 to the upward state shown using the dotted line, and to gradually pull the rods 44 toward the cylinder body.
Accordingly, the nuclear fuel bundle 300 inclined to the left is pulled to the right by the left pusher block 46, and the nuclear fuel bundle 300 inclined to the right is pulled to the left by the right pusher block 46. The above process is performed in a state where the nuclear fuel bundle 300 is rotated to minimize a local friction with the first and second belts 26a and 26b.

The nuclear fuel bundle 300 adjusted in position by using the position adjusting unit 40 is measured through the length and profile measuring unit 50.
The length and profile measuring unit 50 operates the double-acting pneumatic cylinders 54, which are disposed coaxially with the nuclear fuel bundle 300 at both end sides of the nuclear fuel bundle 300, to move the moving member 54a, which is fitted to and run at the guide 54c on the slide base 54b, toward both sides of the nuclear fuel bundle 300.
Additionally, the plurality of linear variable measurement sensors 52 moved toward the nuclear fuel bundle 300 through the moving member 54a are operated to allow the touch rods 52a to be in contact with the end plate 314 prepared at both ends of the nuclear fuel bundle 300. Each of the linear variable measurement sensors 52 transmits the voltage values, which indicate a pressurized degree, to the control unit 200.

Since the distance values for the voltage values are previously programmed, the control unit can convert the length of the corresponding nuclear fuel bundle 300 by using the voltage value.

Four linear variable measurement sensors 52 moved toward the both sides of the nuclear fuel bundle 300 by the double-acting pneumatic cylinders 54 are mounted on the holder 58 as shown in FIG. 6A, and symmetrically disposed centering on the nuclear fuel bundle 300 as shown in FIGS. 1 and 3. The control unit programs and converts the voltage values, which are outputted from the pairs of the linear variable measurement sensors 52 facing with each other, to indicate the length of the nuclear fuel bundle 300 at that point. Accordingly, the output values detected by each of four pairs of the linear variable measurement sensors 52 can be converted into the length of the nuclear fuel bundle 300 at four points.

If the rotating motor 56 is activated in the above state, the linear variable measurement sensors 52 are rotated in the circumferential direction of the nuclear fuel bundle 300. While the linear variable measurement sensors 52 are rotated, the touch rods 52a are moved along the profile of the nuclear fuel bundle 300 such that the linear variable measurement sensors 52 sequentially transmit the output values different from one another.

Accordingly, the control unit 200 can not only detect the length of the corresponding nuclear fuel bundle 300 on the basis of the output values but also detect and output the profile of the corresponding nuclear fuel bundle 300 with reference to a difference of the lengths of the circumferential direction of the nuclear fuel bundle 300.

Diameter measurement of nuclear fuel bundle and Profile measurement of nuclear fuel bundle For this, the present invention uses a diameter and profile measuring unit 70 as shown in FIGS. 7A, 7B and 7C.
In case that the diameter and profile measuring unit 70 measures the diameter of the nuclear fuel bundle 300 and the profile of the nuclear fuel rod 310 positioned at an outer side of the nuclear fuel bundle 300, the ball screw 80 is rotated due to an operation of the transfer motor 76 at the positions of the linear variable measurement sensors 72 of the overturned U-shaped fixing member 74 out of the nuclear fuel bundle 300. The ball screw 80 is stopped at a predetermined position of one side of the nuclear fuel bundle 300.

If the pneumatic cylinder 72b of the overturned U-shaped fixing member 74 is operated by a command of the control unit in the above state, the linear variable measurement sensors 72 are moved toward the nuclear fuel bundle. An end of the touch rod 72a is in contact with an outer surface of the outer nuclear fuel rods 310 corresponding to the diameter of the nuclear fuel bundle 300.

Additionally, if the diameter of the nuclear fuel bundle 300 is measured in the above state, the transfer motor 76 is additionally activated to move the linear variable measurement sensors 72 in the lengthwise direction of the nuclear fuel bundle 300, and travel the linear variable measurement sensors 72 from one end to the other end.
Accordingly, the linear variable measurement sensors 72 move in the lengthwise direction of the nuclear fuel bundle 300 while detecting a surface profile of the corresponding nuclear fuel rod 310. Further, the detected values, which are obtained by measuring the surface profile of the corresponding nuclear fuel rod in the lengthwise direction of the nuclear fuel bundle 300, are converted into the diameter of the nuclear fuel bundle 300 by the program of the control unit in the lengthwise direction of the nuclear fuel rod 310 contacting with the linear variable measurement sensors 72.
Meanwhile, the diameter and profile measuring unit 70 performs the measurement, not only one time, but a plurality of times for each of the plurality of nuclear fuel rods 310 disposed at the exterior of the nuclear fuel bundle 300.
That is, in case of the 37-rod nuclear fuel bundle, the nuclear fuel rods 310 positioned at an external side of the 37-rod nuclear fuel bundle are eighteen in number.
Therefore, the nuclear fuel bundle 300 is rotated at least nine rounds on the rotary unit 20. The linear variable measurement sensors 72 are reciprocated around the nuclear fuel bundle 300 at nine times while measuring the diameter of the nuclear fuel bundle 300 every length.

Further, the detected values obtained through the above process are converted into the lengthwise profile of at least eighteen outer nuclear fuel rods 310 for reproduction and output.

Alternatively, the reference setting sensor 90 is provided to accurately rotate the nuclear fuel bundle 300 at a predetermined angle on the rotary unit 20. The reference setting sensor 90 has a maximal diameter, which is detected by the touch rod 90a at a predetermined point of any one of the nuclear fuel rods 310 disposed at the outer of the nuclear fuel bundle 300, as a reference point.

At the reference point, the front and rear linear variable measurement sensors 72 provided at the overturned U-shaped fixing member 74 are preset to detect the diameter of the nuclear fuel bundle 300.

Additionally, a new pair of nuclear fuel rods 310 are rotated using the rotary unit 20 at a predetermined angle such that the front and rear linear variable measurement sensors 72 measure the diameters of the pair of nuclear fuel rods 310. If the nuclear fuel rods 310 are finally rotated at nine times, eighteen nuclear fuel rods 310 are all completely measured.

Further, In case that the nuclear fuel bundle 300 is the 37-rod nuclear fuel bundle, the linear variable measurement sensors 72 are horizontally mounted to face each other on the front and rear sensor mounts 88a and 88b provided at the overturned U-shaped fixing member 74. In case that the nuclear fuel bundle 300 is the CANFLEX nuclear fuel bundle, the linear variable measurement sensor 72 is horizontally mounted on the front sensor mount 88a, and the linear variable measurement sensor 72 is aslant mounted on the rear sensor mount 88b as shown using the dotted line in FIG. 8B to measure the nuclear fuel rods 310 most adjacent to the diameter of the corresponding nuclear fuel bundle 300.
In other words, In case that the nuclear fuel bundle 300 is the CANFLEX nuclear fuel bundle, the nuclear fuel bundle 300 is rotated at least eleven times on the rotary unit 20 since the nuclear fuel rods 310 positioned at the outer of the nuclear fuel bundle is twenty one in number.
The linear variable measurement sensors 72 are reciprocated at least eleven times around the nuclear fuel bundle 300 while measuring the diameter of the nuclear fuel bundle 300 every length. Further, the detected values obtained from the above process are converted into the lengthwise profile of at least twenty-one outer nuclear fuel rods 310 for reproduction and output.

Image inspection for surface of nuclear fuel bundle The inventive dimension measuring and inspecting system 1 can precisely inspect the surface of the nuclear fuel bundle 300 by using the radiation tolerant camera 155.

For this, the inventive radiation tolerant camera 155 can access the nuclear fuel bundle 300 by moving by about 580mm in the lengthwise direction of the nuclear fuel bundle 300 along the first shaft rail 157 due to the operation of the first driving motor 160 of the inspecting unit 150, and moving by about 200mm in the diameter direction of the nuclear fuel bundle 300 due to the operation of the second driving motor 174.

Further, the radiation tolerant camera 155 can accurately photograph a desired portion of the nuclear fuel bundle 300 by using a self built-in tilting function. An image signal is remotely transmitted to the worker through the image controller unit 216, the control computer 210 and the inspection image monitor 232.

Additionally, the workers can allow the camera 155 to move to a desired position through the operation and the tilting function of the first and second driving motors 160 and 174, and allow the image to be transmitted by photographing the end plate 314 of the nuclear fuel bundle 300 through the mirror 180.

Further, when the image is photographed, the rotary unit 20 is driven to rotate the nuclear fuel bundle 300 in the circumferential direction such that the nuclear fuel rods 310 disposed at the outer of the nuclear fuel bundle 300 are photographed in close-up by using the camera 155, and an image capturing function of the image controller unit 216 is used to precisely photograph the desired portion.
Resultantly, the exterior of the nuclear fuel bundle 300 can be inspected.

Meanwhile, in the above description, a description for a procedure of obtaining the measured values by using the plurality of sensors 52, 72 and 90 is mainly described, and a description for a calibration procedure of the sensors and their parts is omitted. However, the present invention necessarily needs a previous confirmation procedure as to whether or not a variety of measuring parts can accurately detect the measured values in the same manner as other precise measuring apparatuses, and the calibration procedure of calibrating erroneous values.

However, a detailed description of the part precision-degree confirmation and calibration procedure for the accurate activation and detection of the variety of parts and elements is omitted since a general technology known to the art can be used.

Additionally, as an example, only some of main procedures and functions are described in the above description, but the present invention is not limited to this.
S Through the measured values, the present invention can not only measure the surface profile of the nuclear fuel rod, the profile of the end plate of the nuclear fuel bundle, the diameter and length of the nuclear fuel bundle and the like, but also detect the profile of a bearing pad and a cylindricity of the nuclear fuel bundle. Further, the present invention can not only remotely inspect a surface defect of the bearing pads of the nuclear fuel rods 310, a welding portion of the end plate 314, an end cap and the like, but also can be fully utilized even for a quality management of various other management items.

As described above, the present invention can accurately measure or detect the dimension of the nuclear fuel bundle 300 in atmosphere or in the water chamber of the Heavy water reactor, and can utilize a variety of obtained data to evaluate the entirety of the nuclear fuel bundle loaded and irradiated in the nuclear fuel channel.
Accordingly, the present invention has an effect in that the nuclear fuel bundle 300 is evaluated in entirety to improve the safety of the heavy water reactor and to be utilized even for the development of a new CANDU nuclear fuel.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (20)

1. A dimensional measurement and inspection system of a nuclear fuel bundle in air or water chamber (reception bay) of a heavy water nuclear reactor, the system comprising:

a dimension measuring unit for measuring a dimension of the nuclear fuel bundle;
an inspecting unit for moving in a lengthwise direction of the nuclear fuel bundle, and for inspecting a surface of the nuclear fuel bundle through a radiation tolerant camera;
and a control unit for automatically processing a variety of data and image data, which are provided from the dimension measuring unit and the inspecting unit, by using a control computer, wherein the dimension measuring unit further comprises:

a rotary unit disposed at a side position of the inspecting unit, and rotating the nuclear fuel bundle which is put on the rotary unit;

a length and profile measuring unit disposed at a position adjacent to two ends of the rotary unit, and measuring a length of the nuclear fuel bundle and a profile of end plates of the nuclear fuel bundle which is rotated on the rotary unit by using a plurality of linear variable measurement sensors (LVDT); and a diameter and profile measuring unit moving in the lengthwise direction of the nuclear fuel bundle, and measuring a diameter and an outward surface profile of the nuclear fuel bundle;

whereby the nuclear fuel bundle is accurately measured and inspected in air or water to output its resultant values.

2. The system according to claim 1, wherein the dimension measuring unit and the inspecting unit are positioned on a predetermined sized support plate, frames are upwardly protruded from two corners of the support plate, and a hook frame is disposed at a center of the frame to hang on a hook of a crane.

3. The system according to claim 1, wherein the rotary unit has a rotary motor, a driving pulley connected to a shaft of the rotary motor, an infinite-loop type first belt loaded on the driving pulley, a plurality of first driven pulleys, second driven pulleys corresponding to the first driven pulleys, a second belt loaded on the second driven pulleys, and a lower third driven pulley located opposite to the driving pulley, such that when the nuclear fuel bundle are loaded at the left and right sides on the first and second belts 26a and 26b, the nuclear fuel bundle is rotated on the first and second belts due to the operation of the rotary motor.

4. The system according to claim 1, wherein the dimension measuring unit further comprises a position adjusting unit for adjusting left and right positions of the nuclear fuel bundle putted on the first and second belts, the position adjusting unit comprises a plurality of rotary cylinders and a rod having an end for mounting a pusher block thereon, and a plurality of rollers are mounted on the pusher block to provide a pushing force without damaging end plates of the nuclear fuel bundle such that the plurality of rollers push the nuclear fuel bundle to adjust the position of the nuclear fuel bundle.

5. The system according to claim 4, wherein the position adjusting unit allows the plurality of rollers to pull the nuclear fuel bundle during the rotation of the nuclear fuel bundle on the first and second belts, thereby minimizing a local abrasion when the nuclear fuel bundle is moved.

6. The system according to claim 1, wherein the length and profile measuring unit comprises a plurality of linear variable measurement sensors, double-acting pneumatic cylinders for moving the linear variable measurement sensors to the left and right in a lengthwise direction of the nuclear fuel bundle on the rotary unit, and rotating motors for rotating the linear variable measurement sensors in a circumferential direction of the nuclear fuel bundle.

7. The system according to claim 6, wherein the linear variable measurement sensors (LVDT) are fixed on a holder in a row to be arranged at a center of the nuclear fuel bundle and a center of each ring of the nuclear fuel bundle, and wherein when the linear variable measurement sensors are rotated one time, they are turned one time around end plates provided at both sides of the nuclear fuel bundle.

8. The system according to claim 6, wherein the double-acting pneumatic cylinder has a moving member movably fitted to a guide on a slide base, and the rotating motor is mounted on the moving member to rotate the linear variable measurement sensors in the circumferential direction of the nuclear fuel bundle, and the double-acting pneumatic cylinder moves the linear variable measurement sensors in the lengthwise direction of the nuclear fuel bundle.

9. The system according to claim 1, wherein the diameter and profile measuring unit comprises a pair of linear variable measurement sensors disposed to horizontally face each other at front and rear sides of the nuclear fuel bundle, a fixing member for allowing the linear variable measurement sensors to traverse the nuclear fuel bundle and to be disposed horizontally to the nuclear fuel bundle so as to measure the outward surface profile of the nuclear fuel bundle, and a transfer motor, a guide rail and a ball screw for moving the fixing member in the lengthwise direction of the nuclear fuel bundle.

10. The system according to claim 9, wherein the diameter and profile measuring unit further comprises a reference setting sensor, wherein the reference setting sensor detects a maximal diameter of any one outer nuclear fuel rod of the nuclear fuel bundle, the linear variable measurement sensors are disposed to respectively correspond to the maximal outer diameters of the nuclear fuel rods being in contact with the reference setting sensor.

11. The system according to claim 9, wherein the fixing member comprises front and rear sensor mounts, and wherein the front sensor mount has a vertical straight-line type structure for horizontally mounting the linear variable measurement sensor, and the rear sensor mount is constructed to have a slant portion (S) at its middle side and a straight-line portion (Sa) at its lower side to allow the linear variable measurement sensor to be selectively mounted at different slant angles.

12. The system according to claim 11, wherein if the nuclear fuel rods are 37 (37-element fuel bundle) in number, the linear variable measurement sensors on the sensor mounts are horizontally mounted to face each other, and if the nuclear fuel rods are 43 (CANFLEX fuel bundle) in number, the linear variable measurement sensor is horizontally mounted on the front sensor mount and the linear variable measurement sensor is aslant mounted on the slant portion (S) of the rear sensor mount.

13. The system according to claim 1, wherein the inspecting unit comprises a first driving motor and a left and right moving block for moving the camera in the lengthwise direction of the nuclear fuel bundle, the left and right moving block comprises a front and rear moving block and a second driving motor disposed to be vertical to the movement direction of the left and right moving block on its upper plane, and the radiation tolerant camera is mounted on the front and rear moving block to access to the nuclear fuel bundle in the lengthwise direction of the nuclear fuel bundle through an activation of the first driving motor and in the diameter (radius) direction of the nuclear fuel bundle through an activation of the second driving motor.

14. The system according to claim 13, wherein the first driving motor has a rotary shaft connected to one end of a ball screw, the ball screw is disposed along a pair of first shaft rails disposed in the lengthwise direction of the nuclear fuel bundle, and the left and right moving block is screwed into the ball screw to move the camera in the lengthwise direction of the nuclear fuel bundle through the activation of the first driving motor.

15. The system according to claim 13, wherein the second driving motor has a rotary shaft for mounting a pinion gear thereon, and the pinion gear is geared into a fixed rack gear along a second shaft rail at one side of the left and right moving block such that when the second driving motor is activated, the radiation tolerant camera can be moved in the diameter (radius) direction of the nuclear fuel bundle.

16. The system according to claim 13, wherein the inspecting unit has a plurality of mirrors at an opposite side of the camera to indirectly photograph the end plates, which are not directly photographed by the camera, thereby preventing a blind spot.

17. The system according to claim 16, wherein the mirror has an angle controlling plate for controlling a mount angle to incline a mirror surface in up and down directions of the nuclear fuel bundle, and the angle controlling plate has a plurality of circular arc-shaped holes for joint screws.

18. The system according to claim 1, wherein the control unit comprises:

a sensor control unit electrically connected to each of the linear variable measurement sensors and a reference setting sensor to control operations of the linear variable measurement sensors and the reference setting sensor, and receiving and processing a signal from the linear variable measurement sensors and the reference setting sensor;

a motor control unit for controlling motors and double-acting pneumatic cylinders to move the linear variable measurement sensors to a desired position; and an image control unit for collecting and processing images photographed by the camera.

19. The system according to claim 1, wherein a control unit comprises a displaying unit having an inspection image monitor and a control-state displaying monitor for providing and outputting processed detected values and measured values to external workers, and the control unit has an image recorder and a personal computer to transmit and store a variety of measured values and detected values.

20. The system according to any one of claims 1 to 17, wherein the linear variable measurement sensors, the reference setting sensor, the motors, the cylinder and the camera all have a watertight structure to be operated in atmosphere or in the water chamber (W) (reception bay) of the Heavy water nuclear reactor.