JPH0133795B2 - - Google Patents

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a nuclear fuel assembly.

[Background of the invention]

The structure of a conventional fuel assembly will be explained based on FIGS. 1 and 2. The fuel assembly 1 consists of an upper tie plate 2, a lower tie plate (not shown), a plurality of fuel rods 6, and a channel box 7. The upper and lower ends of the fuel rods 6 are supported by an upper tie plate 2 and a lower tie plate (not shown), respectively. subesa (not shown)
are arranged at several locations in the axial direction of the fuel rods 6, and maintain the fuel rods 6 at predetermined intervals. The channel box 7 surrounds the outside of the bundle of fuel rods 6,
Clips 8 provided at the two upper corners of the channel box 7 connect posts 3A, 3B, 3C and 3D provided at the four corners of the upper tie plate.
Posts 3A and 3C that exist diagonally
is placed on the top of the Post 3A has screw hole 5.
is provided. A channel fastener 9 is installed at one corner of the channel box 7.
Channel Box Asuna 9 is Channel Box 7
It is fixed to the post 3A by a fixing screw 10 that passes through the grip 8 and is attached to the screw hole 5.
The channel box 7 is also attached to the post 3A, that is, the upper tie plate 2, by means of fixing screws 10.
Fixed. A handle 4 is provided on the upper tie plate 2.

Fuel assembly 1 loaded in the core of a nuclear reactor
If the channel box 7 is deformed, the fuel assembly 1 is removed from the core and moved into the fuel storage pool. The deformed channel boxes 7 are removed from the fuel assembly 1 and new channel boxes 7 are installed in each case. However, when attaching a new channel box 7 to the fuel handle in the fuel storage pool, the channel box 7 may ride on the post or fall between the post and the handle, making it impossible to attach it smoothly. For this reason,
It takes a long time to install the channel box 7. The fuel handle is the fuel assembly with the channel box removed.

[Purpose of the invention]

An object of the present invention is to provide a fuel assembly that allows a channel box to be smoothly and reliably attached to a fuel handle.

[Summary of the invention]

A feature of the invention is that only two posts located diagonally near the handle's two attachment points to the upper tie plate have their upper ends connect the lower end of the channel box to the top. It has a guide that leads toward the side wall of the tie plate,
A guide extends from the upper end of the post toward the side of the handle opposite the post.

[Embodiments of the invention]

A preferred embodiment of the present invention is illustrated in FIGS. 3 and 4.
This will be explained based on the diagram. Figures 3 and 4 are
Showing fuel handle. Upper tie plate 1
1, posts 12A, 12B, 12C and 12D are provided at the four corners of the upper tie plate 11. A screw hole 5 is provided at the top of the post 12A. Guides 13A, 14A and 15A are formed at the upper ends of posts 12B, 12C and 12D, respectively. Guides 13A, 14A and 15
A is provided at the upper end portions of the posts 12B, 12C, and 12D, and is inclined from the center side of the upper tie plate 11 toward the upper tie plate side wall 16 side, that is, toward the outer peripheral side of the upper tie plate 11. As it descends along the guides 13A, 14A, and 15A, it approaches the side wall 16 of the upper tie plate (the outer peripheral side of the upper tie plate). That is, each guide has an inclined outer surface. Guide 13
The height to the top of A and 15A is post 12A.
and higher than the height to the upper end of the guide 14A.
The height to the top of the guide 14A is the height of the post 12A.
is equal to the height of the top of . The handle 4 is arranged between two posts 12B and 12D arranged at two diagonally located corners. Further, the handle 4 is attached to the upper surface of the upper tie plate 11 at two locations near the posts 12 and 12D.

Two posts 12 located near the attachment points (two locations) of the handle 4 to the upper tie plate 11
Guide 13 present at the upper end of only B and 12D
A and 15A are two posts 12B and 12D
extending from the top end of each post toward each side of the handle 4 facing the . That is, the guides 13A and 15A protrude toward the handle 4 from the side surfaces of the posts 12B and 12D that face the handle 4 (the portions of the posts 12B and 12D indicated by broken lines in FIG. 4). The other configuration of this embodiment is the same as the conventional example shown in FIGS. 1 and 2. Clips 8 provided at two corners of channel box 7 contact the upper ends of post 12A and guide 14A. A fixing screw 10 fixes the channel fastener 9 and the clip 8 of the channel box 7 to the post 12A, ie, the upper tie plate 11. channel box 7
is fixed to the upper tie plate 11, thereby forming a fuel assembly 18.

The operation of attaching and detaching the channel box 7 will be explained with reference to FIG.

The channel box attachment/detachment machine 21 includes a main body 22,
It is composed of a cart 23 and a drive motor 24, and is installed along the side wall of a fuel storage pool 25.

The procedure for removing the channel box 7 from the fuel handle, which has reached the end of its service life, will be explained below. The fuel assembly 18 is inserted into the lower support 26 and upper support 27 of the cart 23 of the channel attachment/detachment machine 21 by a fuel grab pull of a fuel exchange cart (not shown), and the fixing screw 10 shown in FIG. 9 was removed and the channel handling tool 2 was mounted on the auxiliary hoist 27 of the fuel exchange trolley.
At 8, the clip 19 of the channel box 7 is grasped and the cart 23 is driven upwards and downwards to remove it.
29 is a sheave, and 30 is a roller chain for driving the cart up and down. FIG. 5 shows the state with the channel box 7 removed and the state immediately before the apparatus. Note that both the fuel handle from which the channel box 7 has been removed and the channel box 7 are located at the water surface 31 of the fuel storage pool 25 from the standpoint of radiation exposure.
It cannot be lifted and moved higher. Therefore, as shown in FIG. 5, the channel box 7 must also be moved underwater by mounting a channel handling device 28 on the auxiliary hoist 27 of the fuel exchange truck. Next, the procedure for inserting the fuel bundle into the channel box 7 will be explained.

In FIG. 6, the channel handler 28 mounted on the auxiliary hoist 27 of the fuel exchange cart is operated to grab the new channel box 7 in the fuel storage pool 25, and hold it to the top of the fuel handle held on the cart 23. cause. In addition, when lifting the channel box 7, the worker must use the channel handling tool 28.
The claw 34 is opened by pulling up the actuator rod 33 inside. After positioning,
Rewind the auxiliary hoist 27 and attach the channel box 7 to the fuel handle. The lower end of the channel box 7 first descends along the inclined surface 13 of the post 12B or the inclined surface 15 of the post 12D. Therefore, there are 4 in channel box 7.
The book post is inserted securely. That is, the channel box 7 does not remain on the upper end of the post or fall between the post and the handle 4 as in the conventional case. Therefore, the installation work of channel box 7 is carried out in a deep part of the water by remote control.
can be reliably attached to the fuel handle in a short time. The risk of radiation exposure to workers is also significantly reduced. Each guide provided on the post guides the lower end of the channel box 7, which descends when the channel box is attached, toward the upper tie plate side wall 16 side (the outer circumferential side of the upper tie plate). handle 4
Posts 12B and 12D near the base of
Since the guides 13A and 15A are provided at the upper end of the handle 4, the handle 4 can function as a kind of guide. That is, when the handle 4 is first inserted into the lower end of the channel box 7, the range of movement of the channel box 7 in the direction of arrow X (FIG. 4) is limited by the handle 4. For this reason, channel box 7
Post 1 whose lower end is near the base of handle 4
It becomes easy to rest on the guides 13A and 15 provided at 2B and 12D. In this embodiment, as shown in FIG.
extend from the upper ends of the posts 12B and 12D toward the sides of the handle 4 facing the posts 12B and 12D, so that
The upper end of A and 15A is close to the side of handle 4. Therefore, the lower end of the channel box 7 can be easily placed on the guides 13A and 15A. In this embodiment, the lower end of the channel box 7 is guided by the guides 13A and 15A.
Since the top can be easily contacted, the channel box 7 can be attached to the fuel handle as smoothly as an elbow.

Post 12B located near the base of handle 4
If no guide is provided on the upper part of the post 12D, but a guide is provided on the post 12C in other parts, the movable range of the channel box 7 in the direction of the arrow Y (FIG. 4) will be Increases the range of movement in the direction.
For this reason, the upper guide 14A of the post 12C
The proportion of the bottom edge of channel box 7 on top is
This decreases compared to the embodiment described above. (However, it is easier to install channel boxes than before).
It is possible to extend the tip of the guide 14A to near the handle 4, but in this case, the extended guide 14A gets in the way and makes it difficult for the fuel exchange machine to grasp the handle of the fuel assembly loaded in the core. .

The heights of posts 12A, 12b, 12C, and 12D are made equal, and guides 13A, 14A are provided at the upper ends of posts 12B, 12C, and 12D, respectively.
Even if posts 12B and 15A are provided, the posts 12B and 1 are provided with guides at their upper ends, similar to the embodiment described above.
Since the 2D is located near the base of the handle 4, ease of mounting the channel box 7 can be ensured.

〔Effect of the invention〕

According to the invention, a guide present at the upper end of only two posts located near the attachment of the handle to the upper tie plate guides each post toward each side of the handle opposite the posts. This prevents the channel box from falling between the handle and the post. Therefore, the channel box can be attached to the fuel handle smoothly and reliably.

[Brief explanation of drawings]

FIG. 1 is a detailed view of the upper part of a nuclear fuel assembly, FIG. 2 is a view taken in the direction of arrow A in FIG. 1, and FIG. 4 is a view taken along arrow B in FIG. 3, FIG. 5 is an explanatory diagram of the operation of attaching and detaching the channel box, and FIG. 6 is an explanatory diagram of the handling procedure of the channel box. 5...Fuel rod, 7...Channel box, 1
1... Upper tie plate, 12A, 12B, 12
C, 12D... Post, 13, 14, 15... Inclined surface, 18... Fuel assembly, 21... Channel attachment/detachment machine.

Claims (1)

[Claims] 1. An upper tie plate having posts provided at the tops of four corner parts, a lower tie plate, a plurality of fuel rods whose upper and lower ends are respectively held by the upper and lower tie plates, and the fuel rods. A channel box is placed around the outer periphery of the bundle of rods, and two box boxes are placed diagonally.
a handle installed between two of the posts and attached to the upper surface of the upper tie plate at two locations near the posts;
Only the two posts located near the attachment points have guides at their upper ends that guide the lower ends of the channel boxes toward the side walls of the upper tie plate, the guides comprising: A fuel assembly characterized in that the fuel assembly extends from the upper end of the post toward the side surface of the handle that faces the post.