JPH0464600B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a shield plug structure through which piping penetrates through a nuclear reactor housing wall, and can greatly improve work efficiency during periodic inspections and modifications. Concerning the structure of the shield plug of the reactor shield body.

[Background of the invention]

Figure 3 shows a longitudinal cross-sectional view of the entire reactor containment vessel, and Figure 4 shows details of the shield lug of the conventional reactor shield body, and Figure 4 shows the details of the shield plug assembly and shield plug assembly.
The removal procedure is shown in Figure 5.

A reactor body shielding wall 3 is included in the reactor containment vessel 1 and is provided to shield radiation from the reactor pressure vessel 2. This reactor biological shield wall 3 is a primary shield installed to prevent various types of radiation from being emitted from the reactor during reactor operation and periodic inspections, and to prevent adverse effects on the human body, equipment, materials, etc. It's a wall.

Further, the reactor pressure vessel 2 is provided with various nozzles 4, and these nozzles 4 are connected to piping 5. Furthermore, the piping 5 penetrates the reactor housing wall 3 and is connected to piping inside the reactor containment vessel 1.

This through hole in the reactor bio-insulating wall 3 is the fourth
As shown in the figure, it consists of a steel plate 6 and a plug 7 that is an integral structure of the steel plate and concrete. These plugs 6 and 7 have a notch 8 in the through hole for passing through the pipe.
It has a divided structure of overlapping concave blocks with . Note that FIG. 4 shows a state in which one side of the plug is removed.

Further, the joint portion of the piping 5 connected to the nozzle 4 of the nuclear reactor undergoes an inspection during the service period, that is, an in-service inspection (hereinafter referred to as ISI). For this reason, the thin plug part is
As a concave block structure centered on the through hole, the vertical concave blocks of the right and left halves of the through hole are stacked in a plurality of rows in the axial direction of the through hole and fixed with a stopper 9. This has a structure in which each block-shaped plug 6, 7 can be removed from the outside of the living body shield in the axial direction of the through hole 8.
This structure is designed to secure an inspection port and space for inspection during ISI.

However, as shown in this structure, a large number of main reactor pipings (main steam piping 10, PLR piping 11, etc.) are installed close to each other near the through holes 8 of the plugs 6, 7. Piping 5 passing through through hole 8
requires a detour near the through hole 8.

In addition, the work procedure for ISI inspection of this structure is as follows:
It will look like this:

() Installation of the hanging jig 12 above the reactor housing wall 3 plugs 6 and 7.

()Remove the stopper 9 of the plug.

() Removal of steel plate plugs on the side without piping detour, steel plate and concrete plugs, etc. using a hanging jig, etc. to the outside of the reactor bioshield wall 3.

() ISI workers and work tools are brought in through the space in the plug removal area.

() Using the plug removal area as a foothold, ISI work was carried out in the small space between the reactor biological wall 3 and the reactor pressure vessel 2.

() After the ISI work is completed, the work will be the reverse of Joki () to ().

Furthermore, the space in the plug removal section on one side is just enough for a person to pass through with their backs bent.

This structure has the following problems.

(a) Piping 5 penetrating the reactor biological wall 3
However, since the detour route is near the opening on the outer periphery of the biological shielding wall 3, only one side block of the flexible plugs 6 and 7 can be removed, and sufficient work space cannot be secured for workers and tools during ISI. Loading and unloading is intermittent, causing work delays.

(b) As a working space during ISI, the space between the reactor pressure vessel 2 and the reactor bio-insulating wall 3 is small, and when inspecting the pressure vessel nozzle 4 and piping 5, Since the removed part is used as a scaffold, there is not enough scaffolding space, making it difficult to work.

In order to solve the above-mentioned problems of the prior art, it is strongly desired to improve the structure of the shield plug of the nuclear reactor housing wall penetration port.

Note that the shielding plugs 6 and 7 are independent structures that are fitted into the reactor biological shielding wall 3 and constitute the through hole 8 of the piping 5, so regardless of whether the plant is an existing one or a new one, Shiyahei plug 6,7
Improving the structure itself will improve the rate of ISI or repair work.

As a demonstration of this type of conventional technology,
There is a publication number 95988.

[Purpose of the invention]

The purpose of the invention is to secure a working space for ISI work and repair work at the joint between the reactor pressure vessel nozzle and piping, and to improve the work efficiency and reliability. The object of the present invention is to obtain a flexible plug structure for a nuclear reactor shield body constituting a through hole.

[Summary of the invention]

The present invention provides, as a structural feature, a pipe that penetrates a thin wall of a nuclear reactor, and an extension of the pipe that is bent in one direction in the horizontal direction from a position immediately after the penetration, and a penetration of the thin wall. Between the inner wall surfaces of the through hole〓
In the shrink plug structure in which a divisible shield block is provided between the pipes, at least the shrink block arranged between the pipes in the bending direction is arranged at the upper end between the pipe and the pipes. The block is divided into three upper and lower stages with a height that is less than or equal to the height that allows the block to pass through the distance between the block and the lower end, and each of the three upper and lower stages has no space in the left and right direction. A flexible plug for a nuclear reactor shield body, characterized in that the plug is divided, and a stopper is provided at a portion through which the piping passes through to prevent movement of the shield block in the direction of the piping. structure, and depending on its configuration requirements, the piping that passes through it or the piping that is extended and connected to the piping is passed through the entrance/exit front of the shield block,
Even when the pipe as a whole is bent, it is possible to insert and remove the pipe into and out of the through-hole by using the space between the pipe and the upper or lower end of the pipe, making the block larger and the number of times it must be removed is reduced. It is possible to quickly and efficiently work by reducing the amount of work required to create a wide work space through the through hole, or to block that space. It also has the effect of improving reliability.

[Embodiments of the invention]

The present invention is aimed at securing space for carrying equipment inside the biological wall, ISI, and repair work in the shield plug structure that constitutes the piping penetration in the biological shield wall of a nuclear reactor. The reason is that the entire shield plug has a split block structure that is completely removable.

Examples of the present invention will be specifically described below.

FIG. 1 shows a bird's-eye view of the entire structure of a shield plug for a nuclear reactor shield according to an embodiment of the present invention, and FIG. 2 shows a procedure for removing the plug.

In FIG. 1, the shield plug is composed of divided block-shaped plugs A, B, C, D, E, and F, a stopper 13, and a stopper 9. The divided block-shaped plugs A to F are different from the vertical concave blocks in the conventional structure, and have a structure in which they are divided horizontally and each block-shaped plug can be moved in the horizontal direction.

Furthermore, a square-shaped stopper 13, which constitutes a through-hole for the piping 5, is provided at the center through-hole of each split plug, supporting each of the block-shaped split plugs A to F, and also protecting the reactor's biological body. Plugs A to F are all fixed to the reactor containment vessel 1 side outside the wall 3 with removable fasteners 9 as in the conventional case.

Next, the ISI in the Shiyahei plug of this example is
The work procedure at this time is as follows, as shown in Figure 2.

() Install the hanging jig 12 above the plugs A to F of the reactor housing wall 3 and remove the plug stopper 9.

() Using the lifting jig 12, move the split plugs A and B horizontally and remove them to the outside of the reactor housing shield wall 3.

() Next, using a lifting jig 12 similar to (), pull up the split plug C, stopper 13, and D to the position of the split plugs A and B above,
At the same time, it is moved horizontally and removed to the outside of the living body wall 3.

() Similar to () above, move the split plugs E and F horizontally and remove them to the outside of the living body wall.

() Hereafter, the ISI workers and tools will be brought in and inspected as in the conventional technology.

That is, the procedure for removing the split plugs A to F during the ISI inspection and assembling them after completion of the work is as follows.

Disassembling the split plug is A → B → C → Stopper → D
→E → F and assembly is F → E → D → stopper → C
The procedure is →B→A.

In this embodiment, a split plug A made of a steel plate, a split plug B made of an integral structure of a steel plate and concrete, and a split plug E made of a steel plate and a split plug F made of an integral structure of a steel plate and concrete are separated from each other. Although consideration has been given to making it easy to assemble and disassemble the split plugs, it is not necessary to split the plugs, and if the split plugs are not split, the number of split plugs to be assembled and disassembled will be reduced, so there is no harm in doing so.

In this embodiment, since the configuration and work procedure are as described above, the following effects are achieved.

(a) Since the entire shield plugs A to F that constitute the penetration holes in the biological shield wall 3 can be removed, the reactor pressure vessel nozzle 4 and piping 5 during ISI can be removed.
Sufficient operating space for workers up to the joints can be secured, and the efficiency of carrying in and out of workers and work tools can be improved.

(b) Joint between reactor pressure vessel nozzle 4 and piping 5
Since space can be secured all around the pipe 5 at the rear of the removal of the shield plugs A to F, which are used as scaffolding during ISI, sufficient space can be secured for ISI work and pipe repair work.

(c) Since sufficient space can be secured around the pipe 5 to be worked on, work can be carried out by multiple workers.

Next, other embodiments of the present invention will be described.

In the above-mentioned embodiment, even if the plug is opened only on one side and there is no problem, the entire plug must be opened, that is, all the plugs must be dismantled. This results in wasted work.

For example, as in the conventional structure shown in FIG. 4, it is possible to dismantle the plug on the side opposite to the side where the piping detours in front of the plug.

In other embodiments of the present invention, as mentioned above, if work can be done by opening only one side, only one side has the conventional structure, and if the plug cannot be opened with the conventional structure because the piping is detoured in front of the plug, etc. The present invention is applied only to this plug. That is, it is a combination of the conventional structure and the structure of the present invention.

According to another embodiment of the present invention, more advantageous effects can be obtained in terms of the operability of the plug at the location where the above conditions are met.

Next, the plug opening operation according to the above embodiment will be explained with reference to FIG.

In the figure, arrows indicate the procedure for opening the plug.

That is, for the plug on the side where there is no interference in the direction of dismantling the plug, the flexible plugs 6' and 7' of the conventional structure are used, and the plug is pulled out in the horizontal direction from b to c using the conventional method. and release d on one side. If releasing only one side does not interfere with the work, complete the work with this operation.

Further, when it is necessary to release both sides, the upper plugs A' and B' of the remaining plugs do not interfere with the piping, etc., so that they can be pulled out in the horizontal direction from e to f. Next, since there is a space at the top of the intermediate plug C', move it to the top until it avoids interference such as piping, and then pull it out horizontally (in the direction from g to h).

Thereafter, the stopper 13' is disassembled, and the lower plug is disassembled in either the (i) direction or (j) direction depending on the shape of the interfering object, thereby completing the opening of both sides of the plug.

Restoration work can be done by reversing the above work.

〔Effect of the invention〕

According to the present invention, even if the pipe passes through the front of the flexible block, the flexible block can be assembled quickly by reducing the number of times, or in other words, the number of pieces, of the flexible block being moved in and out of the pipe penetration portion. Since it can be dismantled, a large working space for ISI and repair work can be quickly and efficiently obtained, improving the efficiency and reliability of ISI and repair work.

[Brief explanation of the drawing]

Figure 1 is a bird's-eye view showing the shield plug structure of a nuclear reactor shield body which is an embodiment of the present invention, and Figure 2 is a diagram showing the procedure for removing the shield plug in the embodiment shown in Figure 1. , Figure 3 is a vertical cross-sectional view showing the entire reactor containment vessel, Figure 4 is a bird's-eye view showing the shield plug structure of a conventional reactor shield body, and Figure 5 is the shield shown in Figure 4. FIG. 6 is a diagram illustrating a procedure for removing a plug in another embodiment of the present invention. 1... Reactor containment vessel, 2... Reactor pressure vessel, 3... Reactor biological wall, 4... Reactor pressure vessel nozzle, 5... Piping, 6, 6'... Steel plate plug, 7, 7'...Plug, 8...Through hole, 9
... Stopper, 10 ... Main steam piping, 11 ...
PLR piping, 12...Hoisting jig, 13,1
3'...Stopper, A, A'...Plug A, B,
B'...Plug B, C, C'...Plug C, D,
D'...Plug D, E, E'...Plug E, F...Plug F.

Claims (1)

[Claims] 1. Between the pipe that penetrates the shield wall of the reactor and the extension of the pipe is bent in one direction in the horizontal direction from the position immediately after the penetration, and the inner wall surface of the through hole of the penetration part of the shield wall. In the shield plug structure in which a divisible shield block is disposed between the pipe and the pipe, the shield block disposed at least between the pipe in the bending direction is arranged between the pipe and the pipe. It is divided into three upper and lower stages with a height that is less than the height that allows passage between the upper end and the lower end, and each of the upper and lower three stages is A shield for a nuclear reactor shield, characterized in that the shield is undivided, and a stopper is provided at a portion through which the pipe penetrates to prevent the shield block from moving in the direction of the pipe. Hei plug structure.