JP2886146B1 - Pellet loading device - Google Patents

Abstract

An object of the present invention is to provide a pellet loading device capable of easily performing centering between a cladding tube and a pellet, and easily recovering a pellet chip. SOLUTION: A movable pressing rod 12 cooperates with a guide rod 5 at the time of pellet loading to fix the coating tube H by pressing the vicinity of an opening of the coating tube H downward, and the guide rod 5 and the guide wall 7 are fixed. In cooperation with each other, the pellet P extruded toward the axis of the cladding tube H and the opening of the cladding tube H
The pellet P is guided to this opening so that the axis of the pellet P coincides with the axis of the pellet P. Pellet chips generated at the time of pellet loading are collected by the pellet chip collecting hole 3c provided below the guide rod 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellet loading device, and more particularly, to a technology for centering a cladding tube and a pellet during pellet loading.

[0002]

2. Description of the Related Art A nuclear fuel assembly mounted in a nuclear reactor is formed by bundling a plurality of nuclear fuel rods.
The nuclear fuel rod is about 35 m long in a long clad tube of about 4 m.
It is formed by loading zero nuclear fuel pellets in the cladding tube axial direction in a state of being aligned in one row. The nuclear fuel pellet is made of uranium dioxide powder as a raw material, and is formed into a cylindrical shape having a diameter and a height of about 1 cm through a predetermined forming step, sintering step, grinding step, and the like. The loading of the nuclear fuel pellets into the cladding tube has conventionally been performed using the following pellet loading device.

That is, the conventional pellet loading device comprises a centering fitting having a guide tube disposed so as to face an opening at one end of a cladding tube placed in a horizontal state,
A pellet aligning table having a V-shaped pellet aligning groove disposed adjacent to the centering fitting and for aligning a plurality of pellets in a row in the axial direction to form a pellet array; And a loading pusher having a push rod for pushing the aligned row of pellets toward the guide tube.

When the pellets are loaded into the cladding tube, first, 350 pellets are aligned in the V-shaped pellet alignment groove in a row in the axial direction to form a pellet row. Next, the last part of the row of pellets is pushed toward the guide cylinder by a predetermined distance by the push rod. As a result, 350 pellets forming a pellet row are collectively loaded into the cladding tube through the guide cylinder.

At this time, the axis of the cladding tube and the axis of the pellet must coincide, and if the deviation of the axis between them becomes large, the end face of the pellet contacts or collides with the opening end of the cladding tube. Accidents such as damage or destruction of pellets may occur. In order to prevent such an accident from occurring, the above-described position adjustment of the guide cylinder has been carefully performed in advance so that the deviation between the axes of the two is within a certain range.

[0006]

By the way, the clearance between the inner peripheral surface of the cladding tube and the outer peripheral surface of the pellet tends to be gradually narrowed with the recent sophistication of fuel design. It is about 0.2 mm. Therefore, it is required that the position of the guide cylinder be adjusted more carefully.

However, since the guide cylinder has a cylindrical shape and the displacement of the pellet is constrained in all circumferential directions, the axis of the cladding tube and the axis of the pellet are adjusted by adjusting the position of the guide cylinder. It is difficult to match with high accuracy.

[0008] Further, as the loading of the pellets is repeated,
Since the inner peripheral surface of the guide cylinder gradually wears due to friction with the pellet, it is necessary to re-correct the position of the guide cylinder, but this re-correction is very difficult because the guide cylinder has the above-described cylindrical shape. Met.

Further, since the guide tube has a cylindrical shape, it is difficult to collect pellet chips generated by friction between the inner peripheral surface of the guide tube and the pellet, and the guide is repeatedly loaded while the pellet is repeatedly loaded. The conventional apparatus is liable to cause a so-called "loading jam" due to pellet chips accumulated in the cylinder.

The present invention has been made in view of the above circumstances, and can easily perform centering between a cladding tube and a pellet, and can also easily recover a pellet chip. It is intended to provide a pellet loading device.

[0011]

Means for Solving the Problems As means for solving the above-mentioned problems, the invention according to claim 1 is characterized in that a plurality of cladding tubes placed in a horizontal state are provided at a position facing an opening at one end of the cladding tube. A pellet alignment groove for aligning the cylindrical pellets in a single row in the axial direction to form a pellet row, and extruding the last part of the pellet row aligned in the pellet alignment groove toward the opening. Thereby, in a pellet loading device that sequentially inserts the pellets into the cladding tube,
An axis of the cladding tube and an opening of the cladding tube are disposed between the opening of the cladding tube and the end of the pellet alignment groove facing the opening side along the axial direction of the cladding tube. A pair of guide rods for supporting the vicinity of the opening of the cladding tube and guiding the extruded pellets to this opening so that the axis of the pellets extruded toward coincide with each other,
A guide wall disposed above the pair of guide rods and guiding the pellet to the opening in cooperation with the pair of guide rods, and disposed above an end of the cladding tube,
A movable pressing rod for fixing the vicinity of the opening of the cladding tube in cooperation with the pair of guide rods by pressing the vicinity of the end of the cladding tube downward at the time of loading the pellet. .

According to a second aspect of the present invention, in the first aspect of the present invention, the guide rod has a small-diameter portion for supporting the vicinity of the opening of the cladding tube, a large-diameter portion for guiding the pellets to the opening, It is characterized by having.

According to a third aspect of the present invention, in the second aspect of the invention, the guide rod has a small-diameter portion and a large-diameter portion that are detachable from each other.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the guide wall is formed at an end facing the opening of the cladding tube, and the opening edge of the cladding tube is formed. A contact surface near the opening of the cladding tube in cooperation with the pair of guide rods and the movable pressing rod.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the guide wall can adjust a height and an inclination angle with respect to the pellet guided by the pair of guide rods. It is attached to a fixing bracket.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the pellet is disposed below the pair of guide rods, and the pellet is extruded toward an opening of the cladding tube. And a pellet chip recovering section for recovering pellet chips generated in the process of loading into the cladding tube.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a partially crushed sectional view showing the configuration of the present embodiment, FIG. 2 is a side view of the apparatus shown in FIG. 1, and FIG. 3 is a partially enlarged sectional view of FIG. FIG. 4 is a partially enlarged sectional view of FIG.

First, the schematic configuration of the present embodiment will be described. In FIG.
A guide member 2 is provided between an aligning table 1 having a pellet aligning groove 1a for aligning in a row and a supporting device (not shown) for supporting the cladding tube H in a horizontal state.

The guide member 2 is composed of a lower fixture 3 and an upper fixture 4. The lower fixture 3
A groove 3a is formed along the longitudinal direction, and two guide rods 5 are arranged in this groove 3a in a state of being arranged in parallel, as shown in FIG. These two guide rods 5 are attached to the lower fixture 3 by two setscrews 6, respectively. A drop port 3b and a pellet chip collecting hole 3c are formed at a position below the guide rod 5 in the lower fixture 3 so that the pellet chips falling through the drop port 3b from between the two guide rods 5 are formed. It is to be collected in the pellet chip collection hole 3c.

On the other hand, a groove 4a is also formed on the lower surface of the upper fixture 4 along the longitudinal direction, and a guide wall 7 is arranged in the groove 4a. The length of the guide wall 7 is slightly shorter than the length of the groove 4a, and the end face facing the cladding tube H is retracted from the end face of the upper fixture 4. The guide wall 7 is provided with a height adjusting screw 8.
And the upper fixing bracket 4 so that the position in the height direction and the inclination angle with respect to the horizontal plane can be adjusted by the inclination adjusting screw 9.
Attached to.

An air cylinder device 10 is disposed near the end of the upper fixing member 4 facing the cladding tube H side. The air cylinder device 10 includes an air cylinder 11 and a movable pressing rod 12, and the movable pressing rod 1
Numeral 2 is arranged in a hole 4b formed in the upper fixture 4 so as to be located above the open end of the cladding tube H.

Next, details of the configuration of this embodiment will be described. The pellet alignment groove 1a of the alignment table 1 has a V-shaped cross section.
A plurality of (about 350) pellets P are fed from a pellet feeding mechanism (not shown), and the pellets P are arranged in a single row in the axial direction to form a pellet row.

The guide rod 5 is composed of a large diameter portion 14 occupying most of its length, and a small diameter portion 13 attached to the large diameter portion 14. The small-diameter portion 13 and the large-diameter portion 14 constituting the guide rod 5 have a diameter such that the difference between the respective radii is slightly larger than the thickness of the cladding tube. The small diameter portion 13 and the large diameter portion 14 are formed with a male screw portion 13a and a female screw portion 14a which are screwed to each other, and the small diameter portion 13 and the large diameter portion 14 can be attached to and detached from each other by these screw portions. It has become. Therefore, a plurality of small-diameter portions 13 and large-diameter portions 14 having diameters of various values are prepared in advance, and the combination thereof can be freely changed.

On the inner surface of the guide wall 7, there is formed a groove 7a having a shape conforming to the outer peripheral surface of the pellet P. The end of the groove 7a is cut out at an angle of about 45 ° with respect to a horizontal plane. The contact surface 7b is formed. The guide wall 7
The upper fixture 4 is attached to the upper fixture 4 by two height adjustment screws 8 and two inclination adjustment screws 9.
Is adjusted mainly by a height adjusting screw 8, and the inclination angle of the upper fixing bracket 4 with respect to the horizontal plane is adjusted mainly by an inclination adjusting screw 9.

On the side of the contact surface 7b of the guide wall 7, the open end of the cladding tube H placed horizontally by a support device (not shown) faces, and the edge of the open end is formed. Are in contact with the contact surface 7b. The lower portion of the open end is supported by the small diameter portions 13 of the two guide rods 5 (see FIG. 3).

Next, a centering operation performed on the apparatus of the present embodiment configured as described above will be described. FIG.
As shown in the figure, the value of the step D between the small diameter portion 13 and the large diameter portion 14 of the guide rod 5 is slightly larger than the thickness t1 of the cladding tube H. First, the worker must first enter the large diameter section 14.
Is adjusted so that the gap G1 between the uppermost position on the outer peripheral surface and the lowermost position on the inner peripheral surface of the cladding tube H becomes a predetermined value. This adjustment can be performed by changing the height position of the cladding tube H by adjusting the cladding tube support device side (not shown), or by using various diameters for the large diameter portion 14 side. It can also be performed by combining with the small diameter portion 13. The adjustment at this time is performed in a state where the cladding tube H is pressed downward by the movable pressing rod 12.

Next, the worker adjusts the height adjusting screw 8 so that the height between the uppermost position of the outer peripheral surface of the pellet P supported on the large diameter portion 14 and the uppermost position of the inner peripheral surface of the cladding tube H is adjusted. The guide wall 7 is set so that the gap G2 becomes close to a predetermined value and the gap G3 between the uppermost position of the outer peripheral surface of the pellet P and the lowermost position of the contact surface 7b of the guide wall 7 becomes close to the predetermined value.
Adjust the height of the. After that, the worker adjusts the inclination adjusting screw 9.
Is adjusted, and the guide wall 7 is inclined such that the guide wall 7 forms an inclination angle θ with respect to the horizontal plane. In this way, by inclining the guide wall 7, the passage when the pellet P is guided to the cladding tube H can be initially widened and narrowed as the pellet P approaches the open end of the cladding tube H. Thus, the pellet P can be smoothly loaded into the cladding tube H. Then, the worker finely adjusts the height adjusting screw 8 so that the gaps G2 and G3 become a predetermined value while the guide wall 7 is inclined by an angle θ with respect to the horizontal plane. Thus, the centering operation for aligning the axis of the cladding tube H with the axis of the pellet P is completed.

Next, the pellet loading operation performed after the completion of the centering operation will be described. In FIG. 1, when the cladding tube H is automatically placed in a horizontal state on a cladding tube support device (not shown), the vicinity of the opening end of the cladding tube H is supported on the small diameter portion 13 of the guide rod 5. In addition, the opening edge comes into contact with the contact surface 7b of the guide wall 7. Next, the air cylinder 11 of the air cylinder device 10 operates, and the movable pressing rod 12 presses the vicinity of the open end of the cladding tube H downward. Thus, the vicinity of the open end of the cladding tube H is securely fixed by the small diameter portion 13 of the guide rod 5, the contact surface 7b of the guide wall 7, and the movable pressing rod 12.

Next, 350 pellets P are fed into a pellet alignment groove 1a of the alignment table 1 from a pellet feeding mechanism (not shown), and these pellets P are aligned in a row in the axial direction. A row is formed.
When a pusher (not shown) pushes the rear end of the row of pellets, the row of pellets forms a pellet passage formed between the large diameter portion 14 of the guide rod 5 and the groove 7a of the guide wall 7. To the opening of the cladding tube H. At this time, as described above, the guide wall 7 is adjusted so as to form an inclination angle θ with respect to the horizontal plane, and the pellet passage is wide at first, and becomes narrow so as to be narrowed toward the opening of the cladding tube H. Therefore, the pellet row is smoothly guided to the opening of the cladding tube H.

Then, the gaps G1, G2 shown in FIG.
, G3 are adjusted to a predetermined value, so that the pellet row is smoothly loaded into the cladding tube H without hitting the opening edge of the cladding tube H. When the pellet row is loaded into the cladding tube H in this manner, the movable pressing rod 12 moves upward, and the cladding tube H loaded with the pellets.
Is removed from the cladding support device. Thereafter, the next cladding tube is placed in a horizontal state, and the pellets are loaded into the cladding tube in the same procedure.

While the operation of loading the pellets into the cladding tube is repeated, the pellets P come into contact with the large-diameter portion 14 of the guide rod 5 and the groove 7a of the guide wall 7 to generate pellet chips. It passes between the two guide rods 5 and further falls into the pellet chip collecting hole 3c through the drop port 3b. Therefore, it is possible to avoid the occurrence of “loading jam” due to the accumulated pellet chips as in the conventional device.

The above-described centering operation is a simple operation by adjusting the height adjusting screw 8 and the tilt adjusting screw 9.
Workers can use the cladding tube H at the time of pellet loading with little labor.
Can be accurately matched with the axis of the pellet P. Therefore, even if the large-diameter portion 14 and the groove portion 7a are worn due to the contact with the pellet P and the alignment needs to be readjusted, the readjustment operation can be easily performed.

In the above embodiment, the height adjusting screw 8
Although the number of the inclination adjusting screws 9 is two each, these numbers may be three or more. Although the movable pressing rod 12 is driven by the air cylinder 11, the driving source may be not only air pressure but also hydraulic pressure or a motor.

[0034]

As described above, according to the present invention, the vicinity of the opening of the cladding tube is fixed in cooperation with the movable pressing rod, and the pellet extruded toward the axis of the cladding tube and the opening of the cladding tube. A guide wall for guiding the pellet to the opening of the cladding tube and a pair of guide rods are provided so that the axes of the cladding coincide with each other. In addition, readjustment of the alignment work can be easily performed. Further, according to the above configuration, the pellet chip collecting section can be provided below the pair of guide rods, and the pellet chips generated at the time of pellet loading can be easily collected.

[Brief description of the drawings]

FIG. 1 is a partially broken sectional view showing a configuration of an embodiment of the present invention.

FIG. 2 is a side view of the device according to the embodiment of FIG.

FIG. 3 is a partially enlarged cross-sectional view of FIG. 1 viewed from the AA direction.

FIG. 4 is a partially enlarged sectional view of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Alignment table 1a Pellet alignment groove 2 Guide member 3 Lower fixing metal 3a Groove 3b Drop hole 3c Pellet chip collection hole 4 Upper fixing metal 4a Groove 4b Hole 5 Guide rod 6 Set screw 7 Guide wall 7a Groove 7b Abutment surface 8 Height Height adjusting screw 9 Tilt adjusting screw 10 Air cylinder device 11 Air cylinder 12 Movable pressing rod 13 Small diameter section 14 Large diameter section H Cladding tube P Pellet G1, G2, G3 Gap θ Incline angle D Step t1 Thickness

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-101498 (JP, A) JP-A-62-220898 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G21C 21/02

Claims (6)

(57) [Claims] 1. A pellet alignment for forming a row of pellets by aligning a plurality of cylindrical pellets in a row in an axial direction at a position facing an opening at one end of a cladding tube placed in a horizontal state. A pellet loading device that has a groove and extrudes pellets into the cladding tube sequentially by extruding the rearmost part of the pellet row aligned in the pellet alignment groove toward the opening; It is arranged between the opening and the end of the pellet alignment groove facing the opening side along the axial direction of the cladding tube, and is pushed out toward the axis of the cladding tube and the opening of the cladding tube. A pair of guide rods for supporting the vicinity of the opening of the cladding tube and guiding the extruded pellets to this opening so that the axes of the pellets coincide with each other are disposed above the pair of guide rods, A guide wall that guides the pellets to the opening in cooperation with the pair of guide rods, and is disposed above an end of the cladding tube, and presses downward near the end of the cladding tube when the pellet is loaded. A movable pressing rod for fixing the vicinity of the opening of the cladding tube in cooperation with the pair of guide rods. 2. The pellet loading device according to claim 1, wherein said guide rod has a small diameter portion for supporting the vicinity of an opening of said cladding tube and a large diameter portion for guiding said pellets to said opening. apparatus. 3. The pellet loading device according to claim 2, wherein the guide rod has a small-diameter portion and a large-diameter portion that are detachable from each other. 4. The guide wall is formed at an end facing the opening of the cladding tube, and cooperates with the pair of guide rods and the movable pressing rod by contacting the opening edge of the cladding tube. The pellet loading device according to any one of claims 1 to 3, further comprising a contact surface that fixes an area near the opening of the cladding tube. 5. The guide wall according to claim 1, wherein the guide wall is attached to a fixture so that a height and an inclination angle with respect to the pellet guided by the pair of guide rods can be adjusted. A pellet loading device according to any one of the above. 6. A pellet chip disposed below the pair of guide rods, for recovering a pellet chip generated in a process of extruding the pellet toward an opening of the cladding tube and in a process of being loaded into the cladding tube. The pellet loading device according to any one of claims 1 to 5, further comprising: a pellet chip recovery unit.