JPH1164568A - Centering method of spent fuel rod and equipment therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically lower a fuel rod by a robot, and to perform a highly precise centering by inserting the lower end of the fuel rod to a funnel part once, and elastically deforming the curve of the lower end to release sticking of the lower end. SOLUTION: The upper end of a spent fuel rod 27 is held by a robot, a column 2 is raised to pull out the rod 27 from a pin rack, the rod 27 is carried above the circumferential centering mechanism of the fuel rod holding device 5 of a centering equipment by the horizontal movement of the robot, and the lower end of the rod 27 is fitted to the center of a centering push 6. When the robot arm is moved so that the XY coordinate of end fitting of the upper end of the rod 27 is in symmetric positions around the center of the bush 6, the curve of the lower end of the rod 27 in the inlet of a fine diameter part 6b is elastically deformed to solve the stick. Thus, inspections such as measurement of outer diameter dimension, appearance inspection, and γ-ray measurement of the spent curved fuel, rod can be precisely and stably performed.

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 accurately centering a fuel rod when inspecting a spent fuel rod.

[0002]

2. Description of the Related Art In order to examine the irradiation characteristics of fuel rods after they have been used in a nuclear reactor, inspections such as appearance inspection, dimensional inspection, and gamma ray measurement are sometimes performed. Spent fuel rods may be deformed (irradiation deformation) due to combustion in the nuclear reactor, so it is necessary to accurately place the core of the fuel rod, in other words, to measure the fuel rod straight out of the vertical There is.

Conventionally, in order to center the fuel rod, an operator visually controls the robot and inserts the fuel rod into a funnel-shaped insertion guide. However, this method does not allow automatic work by a robot. The robot can be automatically inserted into the funnel-shaped insertion guide by numerically controlling the robot with known fuel rod shape data.However, if the irradiation deformation of the fuel rod is large, the small diameter portion at the bottom of the funnel is used. The lower end of the fuel rod sticks at the entrance. For this reason, the operation is switched to the robot operation visually by the operator, and the robot shakes the fuel rod and forcibly inserts the fuel rod into the funnel-shaped insertion guide. However, the fuel rod may be damaged and the inspection may not be performed.
In particular, since the wire spacer of the fuel rod of the FBR is spirally wound on the outer peripheral surface, it is often difficult to automatically insert the fuel rod into the funnel-shaped insertion guide by a robot.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a centering method and a facility for centering a used bent fuel rod whose upper end is gripped by a robot with high accuracy. .

[0005]

According to one aspect of the present invention, there is provided a method for centering a spent fuel rod, comprising the steps of holding a robot at an upper end of a spent fuel rod and setting a lower end of the funnel to a funnel. Once the robot is inserted into the funnel of the centering bush, and grips the upper end of the fuel rod, it moves in the opposite direction to the bending direction of the fuel rod to elastically deform the lower end of the fuel rod. The rear fuel rod is lowered into the small-diameter portion of the centering bush and the lower centering bush based on the bending amount data at the lower end thereof, and the fuel rod core is aligned with the center of the centering bush. It is.

Another method of centering a spent fuel rod according to the present invention is to use a robot in which an upper end of a spent fuel rod of an FBR in which a wire spacer is spirally wound on an outer peripheral surface is gripped by a robot. A funnel-shaped centering bush whose upper end is provided with a small-diameter portion of a centering bush provided with a gap about twice the diameter of the wire spacer or a protruding spacer having the same size as the diameter of the washer spacer on the inner peripheral surface of the small-diameter portion. Once the robot inserted the funnel part, and then gripped the upper end of the fuel rod, moved in the direction opposite to the bending direction of the fuel rod to elastically deform the lower end of the fuel rod and rotate the centering bush, Thereafter, the fuel rod is lowered into the small-diameter portion of the centering bush and the lower centering bush based on the bending amount data at the lower end thereof,
The center of the fuel rod is aligned with the center of the centering bush.

Still another method of centering a spent fuel rod according to the present invention is a state in which an upper end of a spent fuel rod is gripped by a robot and the lower end is opened below a funnel-shaped insertion guide. Once the girder roller is inserted, the girder roller is closed, the bend at the lower end of the fuel rod is elastically deformed, and the robot holding the upper end of the fuel rod is moved in the direction opposite to the bending direction of the fuel rod depending on the degree of the bend. The lower end of the fuel rod is elastically deformed, and then the fuel rod is lowered through the small-diameter portion of the insertion guide of the measuring sensor in the girder roller or between the opposing guide rollers based on the data of the amount of bending of the lower end. The core of the fuel rod is aligned with the center of the crossbeam roller or the center between the opposing guide rollers.

A first centering apparatus of the present invention for carrying out one of the above-described methods for centering a spent fuel rod according to the present invention is a method of raising and lowering a spent fuel rod along a column erected on a stage base. A horizontally movable robot having an arm for gripping the upper end of a fuel rod, a funnel portion into which the lower end of the fuel rod having the upper end gripped by the arm of the robot is inserted, and the fuel rod is lowered to center the fuel rod. The fuel rod holding device is provided with a rotatable centering bush having a small diameter portion for performing the above and a fuel rod centering mechanism provided below the rotatable centering bush with the same structure.

A second centering facility of the present invention for carrying out another one of the above-described methods of centering a spent fuel rod of the present invention is a vertical centering apparatus which moves up and down along a column erected on a stage base. A horizontally movable robot having an arm for gripping the upper end of a spent fuel rod of an FBR in which a wire spacer is spirally wound, a funnel portion for guiding the lower end of the fuel rod gripped by the arm of the robot, and a fuel A rotatable centering bush having a gap approximately twice as large as a wire spacer for lowering the rod to center the fuel rod or a small-diameter portion provided with a protruding spacer on the inner peripheral surface, and the same below the rotatable centering bush. A fuel rod holding device provided with a fuel rod centering mechanism having a centering bush having a structure so as to be vertically movable.

In the fuel rod holding device in the first and second centering facilities, a plurality of fuel rod centering mechanisms having different inner diameters of the centering bushes are provided in the circumferential direction of the disk-shaped pallet, and the pallet is supported on the spindle. It is preferable that a positioning selection mechanism is provided rotatably and vertically movable, and a positioning selection mechanism for selectively positioning an arbitrary fuel rod centering mechanism at a predetermined position outside the support shaft.

A third centering apparatus according to the present invention for carrying out still another one of the above-described methods for centering a spent fuel rod according to the present invention is provided with a vertically moving column along a column erected on a stage base. A horizontally movable robot having an arm for gripping the upper end of a spent fuel rod, a funnel-shaped insertion guide into which the lower end of the fuel rod gripped by the arm of the robot is inserted, and a lower part provided below the insertion guide. The fuel rod holding device includes a girder roller or an opposing guide roller for lowering the fuel rod to center the fuel rod.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and an apparatus for centering a spent fuel rod according to the present invention will be described. First,
An example of a preferred centering facility for carrying out one spent fuel rod centering method will be described with reference to the drawings.
In the figure, 1 is a stage base, 2 is a column erected on the stage base 1, and 3 is a scalar type robot provided on the column 2 so as to be movable up and down.
Has a horizontally movable structure having an arm 4 for gripping the upper end of the fuel rod. Numeral 5 is a fuel rod holding device provided on the stage base 1. The fuel rod holding device 5 has funnel-shaped centering bushes 6, 6 'in two stages at intervals vertically as shown in FIG. Rotatable fuel rod centering mechanism 7
In the present embodiment, four fuel rod centering mechanisms 7 having different inner diameters of the centering bushes 6, 6 'are provided at equal angles in the circumferential direction of the disk-shaped pallets 8, 8', as shown in FIG. As shown in FIG. 2, the pallets 8, 8 'are rotatably supported on a support shaft 11 integrated with an outer cylinder 10a of a pallet lifting cylinder 10 erected on a stage base 1 by a lower piston rod 9 as shown in FIG. A pallet elevating cylinder 10 which moves up and down, and a positioning selecting mechanism 12 for selectively positioning an arbitrary fuel rod centering mechanism 7 at a predetermined position outside the pallet elevating cylinder 10. It is. A touch plate 14 having a fuel rod insertion hole 13 above the centering bush 6 is provided at the upper end of the support shaft 11 so as to be swingable about a fulcrum 14a.
A sensor 16 is urged by a spring 15 at the opposite end. The positioning selection mechanism 12 includes:
A selection sensor 17 for centering the fuel rod centering mechanism 7, and the selection sensor 17 allows the disk-shaped pallets 8, 8 '.
The index motor 19 is rotated by a required amount via gears 18 and 18 ', and when the centering bushes 6 and 6' are positioned at predetermined positions by the required amount of rotation of the index motor 19, the pallets 8, 8 Locating pin 20 in hole 8a of lower pallet 8 'for positioning
And a locating pin cylinder 21 for inserting the locating pin. Reference numeral 22 in FIGS. 2 and 3 denotes a cylinder for moving a stopper 23 that supports the outer cylinder 10a of the pallet lifting cylinder 10 when the outer cylinder 10a is raised.

A description will be given of a method of centering a spent fuel rod by the centering equipment of the embodiment configured as described above. First, a pin rack 25 provided on the other side of the stage base 1 shown in FIG. The upper end of the stored spent fuel rod 27 having the end fitting 26 attached to the upper end is gripped by the arm 4 of the SCARA type robot 3, the robot 3 is moved up the column 2, and the fuel rod 27 is moved to the pin rack 2.
The fuel is selected from the inside of the fuel rod 27 in advance in the circumferential direction of the fuel rod holding device 5 shown in FIG. 2 of the centering equipment by the horizontal movement of the robot 3, that is, the rotation of the arm 4. The fuel rod 27 is conveyed above the rod centering mechanism 7 and the lower end of the fuel rod 27 is aligned with the center of the centering bush 6. Next, the robot 3 is slightly lowered and the lower end of the fuel rod 27 is inserted into the funnel 6a of the centering bush 6 to reach the entrance of the small diameter portion 6b. Then, without changing the wrist angle of the arm 4 of the robot 3 holding the end fitting 26 at the upper end of the fuel rod 27, the XY coordinates of the arm 4 are symmetric with respect to the center of the centering bush 6. When the arm 4 is moved, the bending of the lower end of the fuel rod 27 at the entrance of the small diameter portion 6b is elastically deformed and the stick is eliminated. Then, the robot 3 is lowered based on the bending amount data of the lower end portion of the fuel rod 27 measured in advance, and the fuel rod 27 is lowered.
Is lowered. Also at this time, the wrist angle of the arm 4 is constant. When the lower end of the fuel rod 27 passes through the lower centering bush 6 ′, the fuel rod gripping part of the arm 4 of the robot 3 is slowly lowered to the center of the centering bush 6, 6 ′ to lower the fuel rod 27. The stage base 1 is inserted into a cell below a fuel rod insertion hole (not shown). When the end fitting 26 at the upper end of the fuel rod 27 is lowered to above the centering bush 6, the cylinder 22 is operated to retract the stopper 23 outward from the lower side of the outer cylinder 10a of the pallet lifting cylinder 10, Pallet lifting cylinder 1
0, the support shaft 11 integrated with the outer cylinder 10a is lowered, and the pallets 8, 8 'are lowered to set the centering bush 6,
6 'is lowered, and accordingly, the end fitting 26 holding the upper end of the fuel rod 27 is lowered to the level of the upper centering bush 6.

The fuel rod 27, which has been vertically aligned while being centered and held as described above, is moved from the light emitting portion 28a of the laser scan micrometer 28 installed as shown in FIG.
The measurement of the outer diameter is started by the laser beam 29 radiated toward the b, the robot 3 is raised, and the fuel rod 27 having the arm 4 holding the end fitting 26 is slowly raised, and the entire length of the fuel rod 27 is increased. The outer diameter is measured over As the fuel rods 27 rise, the pallet 8, 8 'is raised by the operation of the pallet lifting cylinder 10, and the centering bushes 6, 6' are returned to the original level. , 6 'are measured by the laser beam 29. The fuel rods 27 whose outer diameters have been measured over the entire length are centered bushes 6, 6 '.
And sent by the robot 3 for the next inspection.

When a different type of fuel rod 27 is set in the fuel rod holding device 5 shown in FIGS. 2 and 3, the selection sensor 17 determines the fuel rod holding device 5 in advance according to the dimensions of the fuel rod 27. The index motor 19 is driven to select the fuel rod centering mechanism 7, and the pallets 8, 8 'are rotated by a required amount via the gears 18, 18', so that the required fuel rod centering mechanism 7 is at a predetermined position. It is located. Then, in order to position the pallets 8, 8 ', the locating pin cylinder 21 is operated, and the locating pins 20 are inserted into the holes 8a of the lower pallet 8'. After the fuel rod 27 is set in the fuel rod centering mechanism 7, the outer diameter of the fuel rod 27 is measured in the same manner as described above.

In the above-mentioned spent fuel rod centering equipment, the centering bushes 6, 6 'are mounted on the inner peripheral surface of the small diameter portion 31b as shown in FIGS. When six projecting spacers 30 having the same height as the above are replaced with centering bushes 31, 31 'provided in two upper and lower stages at equal intervals, as shown in FIG.
2 can be inserted into the small-diameter portion 31b of the centering bushes 31, 31 'while rotating the centering bushes 31, 31'.
The outer diameter dimension by the laser beam 29 can be measured with higher accuracy.

Another example of centering equipment for carrying out another method of centering spent fuel rods will be described. Since the scalar type robot shown in FIG. 1 is used as the robot for transporting the fuel rods, the description thereof is omitted. The fuel rod holding device, which is an essential part of the centering equipment, will be described with reference to FIGS. 6, 7, and 8. The fuel rod holding device 35 includes a funnel-shaped insertion guide 36 into which the fuel rod 27 is inserted, and the insertion guide 36. , A two-stage girder roller 38 with a sensor 37 interposed therebetween,
38 ', two upper and lower double-girder rollers 38, 38'
A lower surface of the insertion guide 36 slidably supports a bearing body 40 rotatably supporting a pair of opposing rollers so as to expand or shrink the fuel rod passage 39 surrounded by the rollers. The guide levers 42 and 43 are supported on guide bases 42 and 43 provided on the upper surface of the lower insertion guide 41 and normally urged toward the fuel rod passage 39 by a spring 44 and opened to the opposite side by a link lever 45. The other ends of the levers 49 and 5 are rotatably supported by support frames 48 provided on upper and lower frame plates 46 and 47.
The upper and lower rods 5 of a double-headed double cylinder 53 connected to a cam follower 51 attached to one end of the
4, 54 '.

A description will be given of a method of centering a spent fuel rod by the centering equipment of the embodiment configured as described above. First, in a pin rack 25 provided on the other side of the stage base 1 shown in FIG. The upper end of the stored fuel rod 27 having the end fitting 26 attached to the upper end is gripped by the arm 4 of the SCARA type robot 3, the robot 3 is raised, the column 2 is lifted, and the fuel rod 27 is pulled out of the pin rack 25, and the robot is pulled out. The horizontal movement of the arm 3, that is, the rotation of the arm 4, conveys the fuel rod above the fuel rod holding device 35 shown in FIGS. Next, the robot 3 is slightly lowered to insert the lower end of the fuel rod 27 into the funnel portion 36a of the insertion guide 36, and to reach the entrance of the small diameter portion 36b. Then, the arm 4 of the robot 3 holding the end fitting 26 at the upper end of the fuel rod 27 is not changed in wrist angle, and the XY coordinates of the arm 4 are symmetrical with respect to the center of the insertion guide 31. When 4 is moved, the bending of the lower end of the fuel rod 27 at the entrance of the small diameter portion 36b is elastically deformed and the stick is eliminated. Then, the robot 3 is lowered based on the data of the amount of bending of the lower end of the fuel rod 27 measured in advance to lower the fuel rod 27.
Also at this time, the wrist angle of the arm 4 is constant. Fuel rod 27
The lower end comes out of the small-diameter portion 36b, and the double-head double cylinder 53 is operated in advance to rotate the upper and lower levers 49 and 50. 43 on the outside,
When the girder rollers 38, 38 'are moved outward to pass through the fuel rod passage 39 which is expanded, the double-ended double cylinder 53 is operated in reverse to rotate the upper and lower levers 49, 50 in reverse. As a result, when the load on the link lever 45 is released, the bearing 44 is urged toward the fuel rod passage 39 on the guide bases 42 and 43 by the spring 44, so that the fuel rod 27 is sandwiched between the cross beams 38 and 38 '. Is centered. In this state, the robot 3 slowly descends the fuel rod 27, so that the fuel rod 27 follows the cross-rotating cross-girder rollers 38,3.
It is guided by 8 ′ and inserted into a cell below a fuel rod insertion hole (not shown) of the stage base 1.

The fuel rod 27, which has been vertically held by being centered and held in this way, is swirled on the intermediate plate 52 between the upper and lower two-stage girder rollers 38, 38 'as shown in FIGS. The appearance inspection is performed in the flaw detection coil 55 of the current flaw detection apparatus, and the detection of a defect is started. In this way, the appearance inspection is performed over the entire length of the fuel rods 27 by raising the robot 3 to detect a defect. The fuel rods 27 whose appearance has been inspected over the entire length are extracted from the insertion guide 36 and sent by the robot 3 for the next inspection.

The fuel rod holding device 35 in the centering equipment shown in FIGS. 6, 7 and 8 performs centering of the fuel rod 27 by two-tiered girder rollers 38 and 38 '.
As shown in FIG. 9, the double roller 56 and the single roller 5
7 are opposed to each other, and these rollers 56 and 57
A fuel rod holding device 58 in which the fuel rod 27 is centered through the fuel rod 27 may be used.

[0021]

As can be seen from the above description, in the method for centering a spent fuel rod according to the present invention, the lower end of the fuel rod is once inserted into a funnel-shaped centering bush or a funnel-shaped insertion guide by a robot. Then, the robot moves in the direction opposite to the bending direction of the fuel rod to elastically deform the bending of the lower end of the fuel rod, and releases the stick at the lower end of the fuel rod. The centering can be performed with a centering bush, or the centering can be performed with a girder roller under the insertion guide or an opposing guide roller, thereby achieving high-precision centering. Therefore, it is possible to accurately and stably perform inspections such as measurement of the outer diameter of the used bent fuel rod, appearance inspection, and γ-ray measurement. Further, in the case of the centering of the fuel rod of the FBR having the wire spacer, if the centering bush provided with the protruding spacer corresponding to the wire diameter on the inner peripheral surface, the centering can be performed with higher precision. However, if the spent fuel rod centering equipment of the present invention is used, the above-described excellent centering method can be performed effectively and efficiently.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a spent fuel rod centering facility of the present invention.

FIG. 2 is a longitudinal sectional view showing an example of a fuel rod holding device in the spent fuel rod centering facility of the present invention.

FIG. 3 is a plan view of FIG. 2;

4 shows another example of the centering bush in the fuel rod holding device of FIG. 2, wherein a is a longitudinal sectional view and b is a plan view.

FIG. 5 is a perspective view showing a spent fuel rod of an FBR inserted into the centering bush of FIG. 4;

FIG. 6 is a front view showing another example of the fuel rod holding device in the spent fuel rod centering facility of the present invention.

FIG. 7 is a partial vertical side view of FIG. 6;

FIG. 8 is a plan view taken along line AA of FIG. 6;

FIG. 9 is a longitudinal sectional front view showing still another example of the fuel rod holding device in the spent fuel rod centering equipment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stage base 2 Column 3 SCARA robot 4 Arm 5 Fuel rod holding device 6, 6 'Centering bush 6a Funnel part 6b Small diameter part 7 Fuel rod centering mechanism 8, 8' Disk-shaped pallet 10 Pallet lifting cylinder 11 Support shaft 12 Positioning selection mechanism 27 Spent fuel rod 30 Projected spacer 31, 31 ′ Centering bush 31 a Funnel part 31 b Small diameter part 32 Wire spacer 33 Used fuel rod of FBR 35 Fuel rod holding device 36 Insertion guide 38, 38 ′ Cross roller 56 Double roller (guide roller) 57 Single roller (guide roller) 58 Fuel rod holding device

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenichi Kuchiki 2-6-5 Minamisuna, Koto-ku, Tokyo Inside Kawasaki Heavy Industries, Ltd. Tokyo Design Office (72) Inventor Atsushi Yukioka Narita, Oarai-machi, Higashiibaraki-gun, Ibaraki Prefecture 4002 Machi, Oarai Engineering Center, Power Reactor and Nuclear Fuel Development Corp. (72) Inventor Tsuyoshi Nagamine 4002, Narita-cho, Oarai-machi, Higashiibaraki-gun, Ibaraki Pref. 4002 Narita-cho, Oarai-machi, Higashiibaraki-gun Power Reactor and Nuclear Fuel Development Corporation Oarai Engineering Center

Claims (7)

[Claims] An upper end of a spent fuel rod is gripped by a robot, and the lower end is inserted into a funnel portion of a funnel-shaped centering bush. The bending direction of the lower end of the fuel rod is elastically deformed by moving in the opposite direction to the bending direction of the fuel rod. Centering the spent fuel rod by lowering the fuel rod into the center of the fuel rod. 2. A robot in which an upper end of a spent fuel rod of FBR in which a wire spacer is spirally wound around an outer peripheral surface is provided, and a lower end thereof is provided with a gap about twice the diameter of the wire spacer. Insert the projecting spacer of the same diameter as the small diameter part of the centering bush or the wire spacer once into the funnel part of the funnel-shaped centering bush provided on the inner peripheral surface of the small diameter part,
Next, the robot holding the upper end of the fuel rod is moved in the direction opposite to the bending direction of the fuel rod to elastically deform the lower end of the fuel rod and rotate the centering bush, and then the fuel rod is moved to the lower end. Centering the spent fuel rods by lowering the centering bush into the small-diameter portion of the centering bush and the lower centering bush based on the bending amount data of the portion to align the center of the fuel rod with the center of the centering bush. Method. 3. An upper end of a spent fuel rod is gripped by a robot, and a lower end of the spent fuel rod is temporarily inserted into an open cross-girder roller below a funnel-shaped insertion guide. The lower end of the fuel rod is elastically deformed, and the robot holding the upper end of the fuel rod is moved in the direction opposite to the bending direction of the fuel rod depending on the degree of the bending to elastically deform the lower end of the fuel rod, and then the fuel rod is bent. Is lowered through the small-diameter portion of the insertion guide of the measuring sensor based on the bending amount data at the lower end thereof, inside the girder roller or between the opposing guide rollers, and the core of the fuel rod is placed between the center of the girder roller or between the opposing guide rollers. A method for centering a spent fuel rod, characterized in that it is aligned with the center of the fuel rod. 4. A horizontally movable robot having an arm that moves up and down along a column erected on a stage base and grips an upper end of a spent fuel rod, and a lower end of the fuel rod gripped by an arm of the robot. A rotatable centering bush having a funnel to be guided and a small-diameter portion for lowering the fuel rod to center the fuel rod, and a fuel rod centering mechanism having a centering bush of the same structure below the rotatable centering bush. Centering equipment for spent fuel rods, comprising a fuel rod holding device provided so that it can be moved up and down. 5. A horizontally movable robot having an arm that moves up and down along a column erected on a stage base and grips an upper end of a spent fuel rod of an FBR in which a wire spacer is spirally wound, and the robot. A rotatable part having a funnel part where the lower end of the fuel rod gripped by the arm is guided, and a small diameter part provided with a protruding spacer on the inner peripheral surface for lowering the fuel rod and centering the fuel rod A fuel rod centering device comprising a fuel rod holding device provided with a vertical centering bush and a fuel rod centering mechanism having a centering bush of the same structure below the centering bush. 6. A fuel rod holding device in a spent fuel rod centering facility according to claim 4 or 5, wherein a plurality of fuel rod centering mechanisms having different inner diameters of centering bushes are provided in the circumferential direction of the disk-shaped pallet. And a pallet rotatably and vertically movable on a support shaft, and a positioning selection mechanism for selectively positioning an arbitrary fuel rod centering mechanism at a predetermined position outside the support shaft. Used fuel rod centering equipment. 7. A horizontally movable robot having an arm that moves up and down along a column erected on a stage base and grips an upper end of a spent fuel rod, and a lower end of the fuel rod gripped by an arm of the robot. A fuel rod holding device composed of a funnel-shaped insertion guide to be inserted and a girder roller or an opposing guide roller provided below the insertion guide to lower the fuel rod to center the fuel rod. Equipment for centering spent fuel rods.