JPS586919B2 - nuclear fuel assembly - Google Patents

Description

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

The structure of a conventional fuel assembly will be explained based on FIGS. 1 and 2.

The fuel assembly 1 includes 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.

Spacers (not shown) are arranged at several locations in the axial direction of the fuel rods 6 to maintain the fuel rods 6 at a predetermined distance from each other.

The channel box 7 surrounds the outside of the bundle of fuel rods 6, and the clips 8 provided at the two upper corners of the channel box 7 are inserted into the posts 3A, 3B, 3C and 3D provided at the four corners of the upper tie plate. , are placed on the upper ends of posts 3A and 3C that are diagonally located.

A screw hole 5 is provided in the post 3A.

A channel fastener 9 is installed at one corner of the channel box 7.

The channel fastener 9 has a fixing screw 10 inserted into the screw hole 5 through the clip 8 of the channel box 7.
It is fixed to the post 3A by.

The channel box 7 is also fixed to the post 3A, that is, the upper tie plate 2, by fixing screws 10.

A handle 4 is provided on the upper tie plate 2.

If the channel box 7 of the fuel assembly 1 loaded in the core of the nuclear reactor is deformed, this fuel assembly 1
is removed from the core and moved into a fuel storage pool.

The deformed channel box 7 is removed from the fuel assembly 1 and a new channel box 7 is installed therein.

However, when installing a new channel box 7 to the fuel bundle in the fuel storage pool, the channel box 7
The handle may ride on the post or fall between the post and the handle, making it impossible to install it smoothly.

Therefore, it takes a long time to install the channel box 7.

A fuel bundle is a fuel assembly with a channel box removed.

It is an object of the present invention to reduce the time required to attach a channel box to a fuel bundle.

A feature of the present invention is that an inclined surface that slopes toward the side wall of the upper tie plate is formed in a portion of the post provided at the upper part of the upper tie plate that is located on the side wall of the upper tie plate.

A preferred embodiment of the present invention will be described based on FIGS. 3 and 4.

Figures 3 and 4 show fuel bundles.

Posts 12A, 12B, 12C and 12D are provided at the four corners of the upper tie plate 11 on the upper surface thereof.

A screw hole 5 is provided at the top of the post 12A.

Slanted surfaces 13, 14 and 15 are formed at the upper ends of posts 12B, 12C and 12D, respectively.

The inclined surfaces 13, 14 and 15 are the posts 12B, 12C.
and 12D located on the upper tie plate side wall 16 side, which is inclined from the center side of the upper tie plate 11 toward the upper tie plate side wall 16 side.

Posts 12B and 12D are taller than posts 12A and 12C.

Further, post 12C has the same height as post 12A.

The other structure of this embodiment is the same as the conventional example shown in FIGS. 1 and 2.

Clips 8 provided at two corners of the channel box 7 contact the upper ends of the posts 12A.

A fixing screw 10 connects the channel fastener 9 and the clip 8 of the channel box 7 to the post 12A, i.e.
It is fixed to the upper tie plate 11.

A fuel assembly 18 is configured by fixing the channel box 7 to the upper tie plate 11.

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 and a cart 2.
3. It is composed of a drive motor 24 and is installed along the side wall of the fuel storage pool 25.

The procedure for removing the channel box 7 that has reached the end of its service life from the fuel bundle will be described 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 grapple of a fuel exchange truck (not shown), and
Loosen the fixing screw 10 shown in the figure and install the channel fastener 9.
The cart 23 is removed and removed by gripping the clip 19 of the channel box 7 with a channel handling tool 28 mounted on the auxiliary hoist 27 of the fuel exchange cart and driving the cart 23 up and down.

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 neither the fuel bundle with the channel box 7 removed nor the channel box 7 can be lifted and moved above the water surface 31 of the fuel storage pool 25 due to radiation exposure.

Therefore, as shown in FIG. 5, the channel box 7 must also be moved underwater by mounting a channel extension tool 28 on the auxiliary hoist 27 of the fuel exchange truck.

Next, the procedure for inserting the channel box 7 into the fuel bundle will be explained.

In FIG. 6, the channel handler 28 mounted on the auxiliary hoist 27 of the fuel exchange trolley is operated to grasp the new channel box 7 in the fuel storage pool 25 and hold it above the fuel bundle held on the cart 23. cause.

The channel box 7 is lifted by the operator pulling up the actuator rod 33 in the channel handling tool 28 to open the claw 34.

After positioning, the auxiliary hoist 2γ is wound back and the channel box 7 is attached to the fuel bundle.

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, the four posts are reliably inserted into the channel box γ.

In other words, unlike conventional methods, the channel box 7 may remain on the top of the post, or the post and handle 4 may
It never falls between.

Therefore, the channel box 7 can be reliably attached to the fuel bundle in a short period of time, although the operation of attaching the channel box 7 is performed by remote control in a deep part of the water.

The risk of radiation exposure to workers is also significantly reduced.

The inclined surface provided on the post functions as a guide when installing the channel box.

Since the height of posts 12B and 12D is increased,
The work of installing the channel box 7 becomes even easier.

Even if the heights of the posts 12A, 12B, 12C and 12D are made equal and the posts 12B, 12C and 12D are provided with slopes 13, 14 and 15, respectively, the channel box 7 can be easily mounted.

According to the present invention, the time required to install the channel box can be shortened, and the risk of radiation exposure to workers is significantly reduced.

[Brief explanation of the drawing]

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. 3 is a detailed view of the upper part of a fuel bundle of a fuel assembly according to a preferred embodiment of the present invention. Figure 4 is B in Figure 3.
The arrow view, 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, 11...Upper tie plate, 12A, 1
2B, 12C, 12D... Post, 13, 14
, 15... Inclined surface, 18... Fuel assembly, 21... Channel attachment/detachment machine.

Claims (1)

[Claims] 1. An upper tie plate having a plurality of posts on the upper part;
A nuclear fuel assembly consisting of a lower tie plate, a plurality of fuel rods whose bottom ends are respectively held by the upper and lower tie plates, and a channel box surrounding the outer periphery of the bundle of fuel rods and attached to the post. A nuclear fuel assembly characterized in that a portion of the post located on the side wall side of the upper tie plate is formed with an inclined surface that slopes toward the side wall side of the upper tie plate. 2. The nuclear fuel assembly according to claim 1, wherein the inclined surface is formed at the upper end of the post.