JPH06258489A - Key member for inspecting and removing fuel rod and operating method thereof - Google Patents

Abstract

PURPOSE:To lessen the exposure of an operator by facilitating the mechanization of an operation for removing a key member and also to attain the reduction of the cost, improvement in reliability and regulation, etc., in regard to the key member which is fitted to a support lattice when a fuel rod is inserted the removed. CONSTITUTION:A wide part 3 is formed in the end part of a key member 1, while a prescribed tilt is provided for an angle formed by the width direction of this wide part 3 and holding faces 4 of a holding device 5, and a slip rotation is given to the key member 1 through the wide part 3 by a holding operation of the holding device 5.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is used for inserting or withdrawing fuel rods of a PWR fuel assembly into a support grid.
The present invention relates to a fuel rod insertion / removal key member and a method of operating the key member.

[0002]

2. Description of the Related Art In a nuclear fuel assembly, fuel rods are provided with a predetermined interval so that they are securely held between upper and lower nozzles so that they can sufficiently perform their performance during operation of a nuclear reactor. , A plurality of support grids are arranged at predetermined intervals in the longitudinal direction of the fuel rod. In order to remove heat from the surface of the fuel rods that generate heat, the support lattices are usually arranged in parallel in a large number of cells divided by the lattices, with a large number of fuel rods and control rod guide thimble tubes in some predetermined positions. In addition, it maintains the necessary gap between the fuel rods and ensures the flow of coolant. This support grid is generally formed by pressing a thin plate of iron-chromium-nickel-based superalloy Inconel into a predetermined shape, as shown in FIG.
As shown in (B), elastic projections 10 and fixing projections 12 that elastically hold the fuel rods in the cells 7 are provided, and a lattice plate with slits is assembled in a vertical and horizontal lattice shape, and various portions above and below the intersecting portions are assembled. It is manufactured by joining and integrating by metallurgical joining means such as welding or brazing.

On the other hand, the large number of fuel rods are elastically held by the elastic projections and the fixed projections in each cell of the support grid as described above. The elastic projections must be pressed and retracted so that they do not damage the fuel rods. Therefore, conventionally, when the fuel rod is inserted into or removed from the support grid, as shown in FIG.
As shown in (A) and (B), the key member 14 provided with a plurality of protrusions 13 ... 13 according to the intervals of the slit grooves 8 ... After being inserted vertically, the key member is rotated by 90 degrees, and the protrusions 13 ... 13 are pressed against the groove edges 11 ... 11 as shown in the drawing, so that the key member 14 causes the elastic projections 10 ...
To press the fuel rod 9 in the non-contact state into the cell 7
It was formed inside.

[0004]

However, according to the above-mentioned conventional method, in order to press the elastic projection, first, as described above, the key member is arranged so that its protrusion is vertical to the slit groove. It must be inserted and then rotated by 90 ° to mount the key member, and must be rotated again 90 ° in the original direction when the key member is removed. In particular, in the removal of the key member, the fuel rod is inserted into the support grid during the process of using the key member, which is a process in which the key member is used. Therefore, the manual work currently performed requires time and effort. In addition to the above problem, there is a problem of exposure of workers to MOX fuel assembly and the like.

The present invention has been made in view of the above circumstances, and by finding a novel structure in the key member or the operating method thereof, the work of removing the key member from the support grid can be performed by a machine. It is intended to make it easy to use and to greatly reduce the exposure of workers.

[0006]

That is, the feature of the fuel rod insertion / removal key member of the present invention which meets the above-mentioned object is that the rod-shaped body inserted into the slit groove provided at the corner portion of each cell of the supporting grid is characterized. In the fuel rod insertion / removal key member having a plurality of protrusions provided on one side in accordance with the slit groove intervals, a wide portion formed to have a required wide width is provided at an end portion of the key member,
The angle formed by the width direction of the wide portion and the protruding direction of the protruding portion is set so as to be twisted by about 10 ° to 80 °.

Further, as described above, the key member operating method of the present invention presses the elastic projection with the key member, and after the fuel rod is inserted and removed, the key member is rotated so that In the method of releasing the engagement, a wide portion formed to have a required wide width is provided at an end portion of the key member, and a sandwiching device that sandwiches the wide portion from both sides is provided, and each sandwiching surface of the sandwiching device and the width of the wide portion. The angle formed by the direction is set to a required angle so that the wide portion of the key member performs sliding rotation by the pinching operation of the pinching device, and when the engagement of the key member with the cell elastic protrusion is released, the pinching device is set. The key member is rotated by the pinching operation of.

[0008]

In the above key member of the present invention, when the wide portion is subjected to a pinching operation in the protruding direction of the key protruding portion or in a direction orthogonal to the key protruding portion, the wide portion obliquely abuts the pinching surface. The wide part slides and rotates. This rotation does not turn the key member exactly 90 degrees, but since the key member is engaged with the elastic protrusion having elastic force, if the key member is rotated to some extent, the elastic force is increased. The engagement is disengaged so that the key member returns to its original angle.

Further, the method of the present invention is also to release the key member from the elastic projection based on the same principle.
Since the key member is rotated by a simple operation of sandwiching the wide portion of the end portion of the key member, the key member operating device can be remarkably simple even when one row of key members is rotated all at once by one operation. It is possible to design with a configuration.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a partial perspective view showing a key member and a sandwiching device according to an embodiment of the present invention, and FIG. 2 is a front view showing a wide portion of the key member and a sandwiching surface of the sandwiching device in the embodiment.

Fuel rod insertion / removal key member 1 of the embodiment of the present invention
As shown in FIG. 1, the rod-shaped body 6 is inserted into the slit groove 8 provided in the corner portion of each cell (not shown) of the support grid S. A plurality of protrusions 2 ... 2 are provided according to the intervals of the slit grooves.

In the present invention, a wide portion 3 is formed at one end of the key member 1 so as to be wide enough so that adjacent key members 1 ... 1 do not interfere with each other. As shown, the angle θ formed by the width direction of the wide portion 3 and the protruding direction of the protruding portions 2 ... 2 is set so as to be twisted by about 45 ° in this embodiment. This angle θ
As shown in FIG. 2, when the wide portion 3 is sandwiched horizontally or vertically by the sandwiching device 5 having the straight sandwiching surface 4, the wide portion 3 makes an angle of sliding rotation, that is, about 10
It is suitable that the angle is from about 80 to 80 °.

Further, it is desirable that the material of the key member 1 has high abrasion resistance and high rigidity against rubbing against the sandwiched surface during rotation, and in addition to this, considering machinability, maraging steel or mar Aging stainless steel is particularly suitable.

The key member operating method of the embodiment is, for example, as shown in FIG. 1, a rod-shaped key member 1 as shown in the slit grooves 8 ... 8 provided at the corners of each cell of the supporting grid S. 1 is inserted, and the projections 2 ... 2 provided intermittently on one side of the key members 1 ...
1 is pressed against an elastic projection (not shown) on the other side of the key members 1 ... 1, and then the key members 1 ... 1 are rotated after the fuel rod is inserted and removed. , The engagement with the elastic protrusion is released. In particular, in the present invention, as shown in FIG. 1, for example, the key members 1 ...
1 is provided with wide portions 3 ... 3 formed to have a required wide width, while as shown in the figure, a sandwiching device 5 for sandwiching the wide portions 3 ... 3 from both sides is provided, and as shown in FIGS. The angles θ, θ ′, θ ₁ and θ ₂ formed by the sandwiching surfaces 4 and 4 of the sandwiching device 5 and the width direction of the widening part 3 are set by the sandwiching operation of the sandwiching device 5 to the wide portion of the key member 1. 3 is set to a required slant as shown in each figure so that the key member 1 is rotated by the pinching operation of the pinching device 5 when the engagement with the cell elastic protrusion of the key member 1 is released. It is what makes me.

In order to set the angle formed by the sandwiching surfaces 4 and 4 of the sandwiching device 5 and the width direction of the wide portion 3 of the key member as described above, the previous embodiment shown in FIGS. 1 and 2 is used. Like the key member of FIG. 3, the wide portion 3 is provided with an angle θ, or the sandwiching surfaces 4 and 4 are provided with an angle θ ′ as shown in FIG. 3, or as shown in FIG. Both the sandwiching surfaces 4 and 4 are provided with mutually opposite angles θ ₁ and θ ₂ ,
Both of these angles (θ ₁ + θ ₂ ) make it possible to obtain sliding rotation of the key member. Further, although not shown, it is also suitable to form the sandwiching surface of the sandwiching device in an arc shape in order to obtain sliding rolling of the wide portion 3.

Therefore, in the key member 1 of the embodiment of the present invention described above, the wide portion 3 is sandwiched from the protruding direction of the key member protruding portion 2 or the orthogonal direction thereof, as shown in FIG. 1, for example. In addition, since the wide portion 3 obliquely contacts the sandwiching surfaces 4 and 4 shown in FIG. 2, the wide portion 3 causes sliding rotation. This rotation is the key member 1
However, since the key member 1 is engaged with an elastic protrusion (not shown) having elastic force,
When the key member 1 is rotated to some extent, the engagement is released so as to be repelled by the elastic force, and the key member 1 returns to the original angle.

In the method of the present invention, the key member 1 is detached from the elastic protrusion based on the same principle, and the key member is simply operated by sandwiching the wide portion 3 at the end of the key member. 1, the key member operating device can be designed with an extremely simple structure as shown in the drawing, even when one row of key members 1 ... 1 is rotated all at once by one operation as shown in FIG. And has the effect.

In the example shown in FIG. 1, the sandwiching surfaces 4 ... 4 of the sandwiching device 5 are provided so as to form pairs as the number of the key members 1 for the sake of the description example continued from FIG. Of course, this uses a pair of vertically long sandwiching surfaces, which can further simplify the device.

Although the embodiment of the present invention has been described above, the shape of the wide portion of the key member has only to be widened as required so that it can act as a lever from the end of the key member, such as a rod-like shape. It can also be shaped. Also, this wide part
In order to remove the key member, it is usually provided at one end thereof, but in the case where a key member divided at the center is used, when the key member is regarded as one, it is provided at both ends.

[0020]

As described above, according to the present invention, the wide portion is formed at the end of the key member, and the angle formed by the width direction of the wide portion and the sandwiching surface of the sandwiching device is provided with a predetermined inclination. By the pinching operation of the pinching device, sliding rotation is imparted to the key member via the wide portion, whereby
The mechanization of the key member removal work can be remarkably facilitated to reduce the labor and time required for this work and to significantly reduce the exposure of the worker. Moreover, the configuration of the operating device can be extremely simplified, and by omitting many power devices and the like required by the currently proposed machine, the cost and weight of the device can be reduced and its reliability can be improved. It has a remarkable effect of greatly improving the adjustment degree.

[Brief description of drawings]

FIG. 1 is a partial perspective view showing a key member and a pinching device according to an embodiment of the present invention.

FIG. 2 is a front view showing a wide portion of the key member and a sandwiching surface of the sandwiching device in the embodiment.

FIG. 3 is a front view showing a wide portion of a key member and a sandwiching surface of a sandwiching device according to another embodiment of the present invention.

FIG. 4 is a front view showing a wide portion of a key member and a sandwiching surface of a sandwiching device according to still another embodiment of the present invention.

FIG. 5 (A) is a plan view of a supporting grid cell before inserting a key member. (B) It is a longitudinal cross-sectional view of FIG.

FIG. 6A is a plan view showing a usage state of a conventional fuel rod insertion / removal key member. (B) It is the same longitudinal cross-sectional view.

[Explanation of symbols]

 1 Key Member 2 Protruding Part 3 Wide Part 4 Clamping Surface 5 Clamping Device 6 Rod 7 Cell 8 Slit Groove 9 Fuel Rod 10 Elastic Protrusion 11 Slit Groove Edge 12 Fixing Protrusion 13 Protruding 14 Conventional Key Member

Claims (2)

[Claims] 1. A fuel rod insertion / removal key in which a plurality of protrusions are provided on one side of a rod-shaped body inserted into a slit groove provided at a corner portion of each cell of the support grid so as to match the intervals of the slit groove. In the member, a wide portion formed to have a required wide width is provided at an end portion of the key member, and an angle formed by the width direction of the wide portion and the protruding direction of the protruding portion is approximately 10 ° to 80 °.
A key member for inserting and removing a fuel rod, which is set so as to be twisted to some extent. 2. A rod-shaped key member is inserted into a plurality of slit grooves provided at the corners of each cell of the support grid, and a protruding portion intermittently provided on one side of the key member is provided in the slit groove. A key member that engages with the edge portion and presses the elastic protrusion on the other side portion of the key member, and then rotates the key member after inserting and removing the fuel rod to release the engagement with the elastic protrusion. In the operation method of (1), a wide portion formed to have a required wide width is provided at an end portion of the key member, while a sandwiching device that sandwiches the wide portion from both sides is provided, and each sandwiching surface of the sandwiching device and the width direction of the wide portion are The angle formed by the pinching device is set to a required angle so that the wide part of the key member makes a sliding rotation by the pinching operation of the pinching device, and when the engagement of the key member with the cell elastic protrusion is released, Rotating the key member by operation Operation of a key member, characterized.