JPH09197082A - Upper tie plate of fuel assembly - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide an upper tie plate of a fuel assembly, which is provided with an overhanging portion and a marking on the upper tie plate of the fuel assembly to facilitate reliable mounting confirmation of a channel box during assembly of the fuel assembly. provide. An upper tie plate of a fuel assembly according to the present invention is a fuel bundle in which a plurality of fuel rods 3 and water rods 4 are bundled by a fuel spacer 5 and supported by an upper tie plate and a lower tie plate 7. In a fuel assembly in which 8 is surrounded by a channel box 2, at least one corner post 23 of the upper tie plate 22 is provided with a horizontal upper surface 25 that is flush with the upper surface of the corner post 20a for fastening the channel box. The overhanging portion 24 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an upper tie plate of a fuel assembly used in a boiling water reactor, and more particularly, it has a function of confirming that the fuel assembly is securely attached to a channel box. Regarding the upper tie plate.

[0002]

2. Description of the Related Art In light water reactors such as boiling water reactors,
A large number of four fuel assemblies are loaded to form a reactor core. As shown in the vertical cross-sectional view of FIG. 8, the fuel assembly 1 includes a plurality of fuel rods 3 and one or several water rods 4 in a rectangular tubular channel box 2 having a substantially square cross section. The fuel spacers 5 are held and held at predetermined intervals.

The plurality of fuel rods 3 are arranged, for example, in 9 rows and 9 columns, and the upper and lower ends of each fuel rod 3 are restrained and fixed by an upper tie plate 6 and a lower tie plate 7. The bundle 8 is formed.
The channel box 2 for the fuel bundle 8
Is fastened to the upper tie plate 6 through the channel fasteners 9, but is not fixed to the lower tie plate 7 and has a lower end free structure.

Incidentally, each fuel rod 3 in the fuel bundle 8
A zircaloy fuel cladding tube is loaded with a large number of fuel pellets, and the upper and lower ends thereof are sealed by an upper end plug 10 and a lower end plug 11. Further, the lower tie plate 7 is formed with a lower end plug supporting hole 12 for supporting the lower end plug 11 and a cooling water guide hole 13, and the cooling water guide hole 13 is used to flow in from an inflow nozzle 14. The cooling water is guided into the channel box 2.

In this lower tie plate 7, a nose piece 15 is integrally provided at the lower end of a thick tie plate body so as to straddle the inflow nozzle 13, and the lower end plug support hole 12 is provided with a fuel. A screw hole is provided to support the lower end plug 10 of the rod 3.

The upper tie plate 6 for restraining the upper portion of each fuel rod 3 has an upper end plug insertion hole into which an upper end plug 10 of the fuel rod 3 is inserted, as shown in a partially cutaway perspective view of FIG. 16
In addition, a large number of cooling water outflow holes 17 are provided, and a handle 18 for gripping and handling the fuel assembly 1 is provided diagonally on the upper portion.

On the outer side of the handle 18, two guide corner posts 19 are formed which serve as guides for inserting the channel box 2, and when the channel box 2 is attached to the fuel bundle 8. , Two independent corner posts 20 for receiving the load are provided diagonally to the handle 18. One of the corner posts 20 is provided with a screw hole to serve as a corner post 20a for fastening the channel box.

As shown in the plan view of FIG. 10, the channel box 2 has a triangular channel at a position corresponding to two corner posts 20 of the upper tie plate 6 so that its own weight is supported by the upper tie plate 6. A clip 21 is provided. Of the two channel clips 21,
The perforated channel clip 21a corresponding to the corner post 20a for fastening the channel box has a hole 21b through which the threaded portion of the channel fastener 9 is inserted.

[0009]

When assembling the fuel assembly 1, a fuel bundle 8 composed of a plurality of fuel rods 3, an upper tie plate 6, a lower tie plate 7 and the like is previously prepared.
Then, the channel box 2 is covered from above, and the perforated channel clip 21a of the channel box 2 is fastened to the corner post 20a for fastening the channel box and fixed to the upper tie plate 6. At this time, the channel box 2 is It is necessary to confirm that the channel bundles 21 and 21a are securely covered with the fuel bundle 8 and that the channel clips 21 and 21a are securely in contact with the corner posts 20 and 20a.

However, except when assembling the fuel assembly 1 at the manufacturing plant, the work of mounting the channel box 2 for assembling the fuel assembly 1 performed in a nuclear power plant or the like is carried out in a deep fuel storage pool under water. The bundle 8 is remotely operated.

Therefore, in the assembly work by remote control in the fuel storage pool or the like, the corner posts 20, 20a of the upper tie plate 6 are hidden behind the channel clips 21, 21a of the channel box 2 and come into contact with each other. Since the confirmation is extremely difficult, the mounting work requires a long time, and there has been a demand for improvement in work efficiency. Further, when handling the fuel assembly 1 performed in a nuclear power plant or the like, measures against radiation exposure of workers must be taken into consideration, and shortening the working time is an extremely important issue from the viewpoint of radiation exposure reduction.

An object of the present invention is to provide an overhang portion and a marking on the upper tie plate of the fuel assembly to facilitate the reliable mounting confirmation of the channel box during the assembly of the fuel assembly. To provide a tie plate.

[0013]

In order to achieve the above object, an upper tie plate of a fuel assembly according to the invention as set forth in claim 1 is formed by bundling a plurality of fuel rods and water rods with a fuel spacer. In a fuel assembly in which a fuel bundle supported by a tie plate is surrounded by a channel box, at least one corner post of the upper tie plate has a horizontal upper surface located on the same plane as the upper surface of the corner post for fastening the channel box. It is characterized in that it is provided with a protruding portion.

When the channel box is attached to the upper tie plate of the fuel bundle, the upper portion of the channel box comes into contact with the horizontal upper surface of the protruding portion formed on the upper portion of the corner post of the upper tie plate, and the end portion can be confirmed. By monitoring the horizontal upper surface of the part, it is possible to easily confirm the reliable mounting of the channel box.

In the upper tie plate of the fuel assembly according to the second aspect of the invention, the protrusion is provided on the horizontal upper surface of the overhanging portion having the horizontal upper surface located on the same plane as the upper surface of the corner post for fastening the channel box. It is characterized by that. When the channel box is securely attached to the upper tie plate, it can be easily confirmed from the horizontal upper surface of the protruding portion of the upper tie plate and the projections formed on the horizontal upper surface and the upper surface position of the channel box.

In the upper tie plate of the fuel assembly according to the third aspect of the present invention, the upper end position of the projection provided on the horizontal upper surface of the overhanging portion having the horizontal upper surface located on the same plane as the upper surface of the corner post, It is characterized in that it is flush with the upper surface of the channel clip of the channel box when the channel box is attached. When the channel box is securely attached to the upper tie plate, the top surface of the channel clip on the upper side of the channel box and the upper end of the protrusion provided on the horizontal upper surface of the overhang portion of the upper tie plate are flush with each other, which facilitates confirmation. You can do it.

In an upper tie plate of a fuel assembly according to a fourth aspect of the present invention, a plurality of fuel rods and water rods are bundled by a fuel spacer, and a fuel bundle supported by the upper tie plate and the lower tie plate is surrounded by a channel box. In the fuel assembly, the guide corner post portion connected to the handle of the upper tie plate is provided with a marking indicating the upper end position of the channel box when the channel box is attached.

When mounting the channel box to the upper tie plate of the fuel bundle, by confirming that the upper end position of the channel box coincides with the marking provided on the guide corner post portion of the upper tie plate, the channel box is securely mounted. Can be easily confirmed.

In an upper tie plate of a fuel assembly according to a fifth aspect of the present invention, a plurality of fuel rods and water rods are bound by a fuel spacer, and a fuel bundle supported by the upper tie plate and the lower tie plate is surrounded by a channel box. In the above fuel assembly, the handle of the upper tie plate is provided with a marking indicating the upper end position of the channel box when the channel box is attached.

When attaching the channel box to the upper tie plate of the fuel bundle, by confirming that the upper end position of the channel box coincides with the marking provided on the handle of the upper tie plate, the reliable attachment of the channel box can be facilitated. Can be confirmed.

In an upper tie plate of a fuel assembly according to a sixth aspect of the present invention, a plurality of fuel rods and water rods are bound by a fuel spacer, and a fuel bundle supported by the upper tie plate and the lower tie plate is surrounded by a channel box. In the above fuel assembly, the guide corner post portion connected to the handle of the upper tie plate is provided with a flat portion located on the same plane as the corner post for fastening the channel box.

When the channel box is attached to the upper tie plate of the fuel bundle, it is ensured that the upper end position of the channel box coincides with the flat portion provided on the guide corner post portion of the upper tie plate. You can easily check the installation.

In an upper tie plate of a fuel assembly according to a seventh aspect of the present invention, a plurality of fuel rods and water rods are bundled by a fuel spacer, and a fuel bundle supported by the upper tie plate and the lower tie plate is surrounded by a channel box. In the fuel assembly, the guide corner post portion connected to the handle of the upper tie plate is provided with an inclined portion whose lower end is flush with the upper surface of the corner post for fastening the channel box.

When the channel box is attached to the upper tie plate of the fuel bundle, it is confirmed that the upper end position of the channel box coincides with the lower end of the inclined portion provided on the guide corner post portion of the upper tie plate. You can easily confirm the reliable mounting.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. The same components as those of the above-described conventional technology are denoted by the same reference numerals, and detailed description thereof will be omitted.
The first embodiment relates to claim 1, and is a plan view of FIG.
3A is a partially cutaway side view, FIG. 3A is an enlarged perspective view of an essential part, and FIG. 3B is an enlarged sectional view of an essential part.

The upper tie plate 22 of the fuel assembly has an upper end plug insertion hole 16 into which the upper end plug 10 of the fuel rod 3 is inserted.
In addition, a large number of cooling water outflow holes 17 are provided, and a handle 18 for gripping and handling the fuel assembly is provided on the upper portion in a diagonal direction.

On the outer side of the handle 18, two guide corner posts 19 are provided which serve as guides when the channel box 2 is mounted, and when the channel box 2 is mounted on the fuel bundle 8. , The independent corner post 23 for receiving the load and the corner post 23a for fastening the channel box are the handle 18
And is provided in a diagonal position.

The corner posts 23, 23a are provided with diagonally projecting portions 24 on their upper portions, and their horizontal upper surfaces 25 are formed at the same height as the upper surfaces of the corner posts 23a for fastening the channel box. ing. This horizontal top surface
25 is configured to have a sufficient length such that the end of the horizontal upper surface 25 can be observed from the end of the channel clip 21, 21a when the channel box 2 is attached.

Next, the operation of the above configuration will be described. The mounting work of the channel box 2 relating to the assembly of the fuel assembly 1 performed in the nuclear power plant or the like is performed by remote control on the fuel bundle 8 deep in the water of the fuel storage pool.

First, when the channel box 2 is put on the fuel bundle 8 from above, the channel box 2 is previously prepared.
The channel clips 21 and 21a of the above are in a direction in which they do not interfere with the handle 18 and the guide corner post 19 serving as the mounting guide, and the perforated channel clip 21a has the corner post 23 for fastening the channel box of the upper tie plate 22.
Position in the direction corresponding to a.

Next, when the channel box 2 is put on the fuel bundle 8 from above, the inner corners of the rectangular channel box 2 are positioned so that the handle 18 and the guide corner post 19 respectively.
And the corner posts 23 and 23a are attached as guides,
The channel clip 21 to the corner post 23,
The perforated channel clip 21a abuts the corner post 23a for fastening the channel box.

As a result, the channel clip 21 of the channel box 2 abuts on the horizontal upper surface 25 of the projecting portion 24 of the corner post 23 of the upper tie plate 22, and the perforated channel clip 21a has the corner for fastening the channel box. The channel box 2 is securely mounted by abutting on the horizontal upper surface 25 of the projecting portion 24 of the post 23a, and the weight of the channel box 2 is supported by the upper tie plate 22.

Further, since the horizontal upper surfaces 25 of the projecting portions 24 of the corner posts 23 for supporting the channel box 2 and the corner posts 23a for fastening the channel box are formed longer than the lengths of the channel clips 21, 21a. Corner post 23,23 when installing 2
The tip of the horizontal upper surface 25 of the protruding portion 24 of a is not hidden behind the channel clips 21 and 21a.

Therefore, with respect to the fuel assembly in water operated remotely, the mounting state of the channel box 2 on the fuel bundle 8 is monitored, and the channel clip 21,
By confirming that 21a is in contact with the corner posts 23, 23a, the reliable attachment can be easily confirmed. Further, since the horizontal upper surfaces 25 of the projecting portions 24 of the corner posts 23 and the corner posts 23a for fastening the channel box are formed on the same horizontal plane, the channel box 2
Are well horizontally supported by the upper tie plate 22.

The second embodiment relates to claim 2 and claim 3, and as shown in the enlarged perspective view of the essential part of FIG. 4A and the enlarged sectional view of the essential part of FIG. The upper part of the upper tie plate 22 of the embodiment is similar to that of the first embodiment except that the protruding parts provided on the corner posts 23, 23a of the upper tie plate 22 are different. A projection 27 is provided at the tip of the horizontal upper surface 25 of the 26 (claim 2).

Further, the height of the protrusion 27 is made equal to, for example, the plate thickness of the channel clips 21 and 21a of the channel box 2, and when the channel box 2 is securely attached to the upper tie plate 22, the channel is The upper surfaces of the clips 21 and 21a and the upper end of the protrusion 27 are located on the same horizontal plane (claim 3).

The operation of the above construction is as follows.
In addition to the operation similar to that of the embodiment, when the channel box 2 is attached to the fuel bundle 8, the channel clips 21 and 21a are placed on the horizontal upper surface 25 of the overhanging portion 26 provided on the corner posts 23 and 23a. Abut.

At this time, it is necessary to confirm whether or not the channel box 2 is securely attached to the fuel bundle 8. In the case of claim 2, the channel clip of the channel box 2 is checked.
This can be easily carried out by checking the positions of the upper surfaces of 21, 21a and the horizontal upper surface 25 and the upper ends of the protrusions 27.

In the third aspect of the invention, the channel clips 21 and 21a of the channel box 2 are the corner posts 2.
When abutting against the horizontal upper surface 25 of the overhanging portion 26 provided on the upper part of the 3, 23a, the upper surfaces of the channel clips 21, 21a and the upper end position of the protrusion 27 of the horizontal upper surface 25 are flush with each other. From the case of claim 2,
It can be done more easily.

The third embodiment relates to claim 4 and, as shown in the partially cutaway perspective view of FIG.
Is a marking 29 such as a marking line indicating the upper end position of the channel box 2 when the channel box 2 is securely attached to the guide corner post 19 connected to the handle 18.
It is configured by engraving a.

Since the surface of the upper tie plate 28, which is generally made of metal, has a matte finish which is not glossy, the marking 29a can be made glossy by, for example, performing a shallow cutting such as a marking line on the surface. It is possible to make a marking 29a having a rich metallic color, which is easily distinguishable from the periphery of the upper tie plate 28 and the channel box 2.

Next, the operation of the above configuration will be described. When the channel box 2 is attached to the fuel bundle 8, the channel clip of the channel box 2
21 and 21a abut on upper portions of the corner posts 23 and 23a (not shown). At this time, when the channel box 2 is securely mounted, the upper surface of the channel box 2 will be at the same position as the marking 29a of the guide corner post 19, so that by confirming this, the channel can be used even in distant water. Whether or not the box 2 is securely attached to the fuel bundle 8 can be easily performed.

The fourth embodiment relates to claim 5, and as shown in the partially cutaway perspective view of FIG. 5, the upper tie plate 28 is used.
Is formed by engraving markings 29b such as marking lines showing the upper end position when the channel box 2 is securely attached near the base of the handle 18. The marking 29b is formed on the surface of the upper tie plate 28, which has a matte finish as in the case of the third embodiment, with a scribe line of metallic color rich in luster or the like.

Next, the operation of the above configuration will be described. When the channel box 2 is attached to the fuel bundle 8, the channel clip of the channel box 2
21 and 21a abut on upper portions of the corner posts 23 and 23a (not shown). At this time, when the channel box 2 is securely mounted, the upper surface of the channel box 2 is located at the same position as the marking 29b of the handle 18. By confirming this, the channel box 2 is surely attached to the fuel bundle. It can be easily confirmed whether or not it is attached to 8.

The fifth embodiment relates to claim 6, and FIG.
As shown in the partially cut-away perspective view of (a) and the main part plan view of FIG. 6 (b), the upper tie plate 30 is fastened to its channel box on the outer side of the guide corner post 19 connected to the handle 18. The corner post 20a is provided with a notch 32 having a horizontal portion 31 at the same height as the upper surface.

Since the surface of the upper tie plate 30 which is generally made of metal has a matte finish with no luster, the notch 32 has a high luster by cutting by machining. Upper tie plate with metal color
It is possible to provide a horizontal portion 31 and a notch 32 which can be easily discriminated from the periphery of 30 and the channel box 2.

Next, the operation of the above configuration will be described. When the channel box 2 is attached to the fuel bundle 8, the channel clip of the channel box 2
21 and 21a abut on upper portions of the corner posts 23 and 23a (not shown). At this time, when the channel box 2 is securely mounted, the upper surface of the channel box 2 becomes flush with the horizontal portion 31 of the notch 32 provided in the guide corner post 19, so check this. Thus, it is possible to easily confirm whether or not the channel box 2 is securely attached to the fuel bundle 8.

The sixth embodiment relates to claim 7, and FIG.
As shown in the partially cutaway perspective view of (a) and the main part plan view of FIG. 7 (b), the upper tie plate 33 is located outside the guide corner post 19 connected to the handle 18, and the lower end thereof is a channel. An inclined portion 34 is provided at the same position as the upper surface of the corner post 20a for fastening the box.

Since the surface of the upper tie plate 33, which is generally made of metal, has a matte finish with no luster, the inclined portion 34 is rich in luster by performing cutting by machining as an example. Upper tie plate 33 in metallic color
It is possible to provide an inclined portion 34 that can be easily distinguished from the surroundings and the channel box 2.

Next, the operation of the above configuration will be described. When the channel box 2 is attached to the fuel bundle 8, the channel clip of the channel box 2
21 and 21a abut on upper portions of the corner posts 23 and 23a (not shown). At this time, when the channel box 2 is securely mounted, the upper surface of the channel box 2 is at the same height as the lower end of the inclined portion 34 provided on the guide corner post 19; It is possible to easily confirm whether or not the box 2 is securely attached to the fuel bundle 8.

In any of the above fourth to seventh embodiments, the markings 29a and 29b, the notches 32 and the inclined portions are formed while the channel box 2 is being mounted.
34 is hidden in Channel Box 2. However, since the channel box 2 does not have the channel clips 21 and 21a on the side of the handle 18 and the guide corner post 19, the markings 29a and 29b, the notch 32 and the sloped portion are formed when the mounting of the channel box 2 is near the end.
The 34 looks better so you can monitor the status of the fitting process.

Further, with respect to the markings 29a, 29b, the notches 32, and the inclined portions 34, the position, thickness, shape, color, etc. of the markings 29a, 29b are variously changed to monitor the mounting state of the channel box 2 on the fuel bundle 8. Therefore, it is possible to easily confirm the reliable mounting.

[0053]

As described above, according to the present invention, when assembling a fuel assembly in a fuel storage pool or the like in a nuclear power plant, it is possible to easily confirm the mounting state of the channel box with the fuel bundle covered with the channels. You can
It is possible to confirm that the channel box is securely attached even when working remotely underwater. As a result, the reliability and efficiency of the work of mounting the channel box are improved, so that the work time can be shortened together with the work process, and the exposure of the worker is also reduced.

[Brief description of drawings]

FIG. 1 is a plan view of an upper tie plate according to a first embodiment of the present invention.

FIG. 2 is a partially cutaway side view of the upper tie plate according to the first embodiment of the present invention.

FIG. 3 is an upper tie plate of the first embodiment according to the present invention, (a) is an enlarged perspective view of an essential part, and (b) is an enlarged sectional view of the essential part.

FIG. 4 is an upper tie plate of second and third embodiments according to the present invention, in which (a) is an enlarged perspective view of an essential part and (b) is an enlarged sectional view of the essential part.

FIG. 5 is a partially cutaway side view of an upper tie plate according to fourth and fifth embodiments of the present invention.

6A and 6B are upper tie plates according to a sixth embodiment of the present invention, in which FIG. 6A is a partially cutaway perspective view, and FIG.

7A and 7B are upper tie plates according to a seventh embodiment of the present invention, in which FIG. 7A is a partially cutaway perspective view and FIG.

FIG. 8 is a vertical cross-sectional view of a fuel assembly.

FIG. 9 is a partially cutaway perspective view of a conventional upper tie plate.

FIG. 10 is a plan view of a conventional upper tie plate.

[Explanation of symbols]

1 ... Fuel assembly, 2 ... Channel box, 3 ... Fuel rod, 4 ... Water rod, 5 ... Fuel spacer, 6, 22,
28, 30, 33 ... Upper tie plate, 7 ... Lower tie plate, 8 ... Fuel bundle, 9 ... Channel fastener, 10 ...
Upper end plug, 11 ... Lower end plug, 12 ... Lower end plug support hole, 13 ... Cooling water guide hole, 14 ... Inflow nozzle, 15 ... Nose piece, 16 ...
Upper end plug insertion hole, 17 ... Cooling water outflow hole, 18 ... Handle, 19
… Guide corner posts, 20, 23… Corner posts, 20a,
23a ... Corner post for fastening channel box, 21 ...
Channel clip, 21a ... Perforated channel clip, 21b ... Hole, 24, 26 ... Overhanging part, 25 ... Horizontal upper surface of overhanging part, 27 ... Projection, 29a, 29b ... Marking, 31 ... Horizontal part, 32 ... Notch, 34 … Sloping part.

Claims (7)

[Claims] 1. A fuel assembly in which a plurality of fuel rods and water rods are bundled by a fuel spacer and supported by an upper tie plate and a lower tie plate and surrounded by a channel box, and at least one of the upper tie plates is provided. Upper tie plate of the fuel assembly, wherein the corner post is provided with an overhanging portion having a horizontal upper surface that is flush with the upper surface of the corner post for fastening the channel box. 2. The upper tie plate, wherein a protrusion is provided on a horizontal upper surface of an overhanging portion having a horizontal upper surface located on the same plane as the upper surface of the corner post for fastening the channel box. Upper tie plate of the described fuel assembly. 3. In the upper tie plate, an upper end position of a protrusion provided on a horizontal upper surface of an overhanging portion having a horizontal upper surface located on the same plane as an upper surface of a corner post is set to a channel of the channel box when the channel box is mounted. The upper tie plate of the fuel assembly according to claim 2, wherein the upper tie plate is flush with the upper surface of the clip. 4. A fuel assembly in which a plurality of fuel rods and water rods are bundled by a fuel spacer and supported by an upper tie plate and a lower tie plate is surrounded by a channel box, and is connected to a handle of the upper tie plate. An upper tie plate of a fuel assembly characterized in that a guide corner post portion is provided with a marking indicating an upper end position of the channel box when the channel box is attached. 5. A fuel assembly in which a fuel bundle in which a plurality of fuel rods and water rods are bundled by a fuel spacer and supported by an upper tie plate and a lower tie plate is surrounded by a channel box, and a channel box is provided on a handle of the upper tie plate. An upper tie plate of a fuel assembly, which is provided with a marking indicating an upper end position of the channel box when mounted. 6. A fuel assembly in which a plurality of fuel rods and water rods are bundled by a fuel spacer and supported by an upper tie plate and a lower tie plate, and a fuel assembly surrounded by a channel box is connected to a handle of the upper tie plate. An upper tie plate of a fuel assembly, characterized in that a flat portion located on the same plane as the corner post for fastening the channel box is provided in the guide corner post portion. 7. A fuel assembly in which a plurality of fuel rods and water rods are bundled by a fuel spacer and supported by an upper tie plate and a lower tie plate is surrounded by a channel box, and is connected to a handle of the upper tie plate. An upper tie plate of a fuel assembly, wherein a lower end of the guide corner post is provided with an inclined portion which is flush with an upper surface of the corner post for fastening the channel box.