JPS60242394A - Shielding wall for nuclear reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a reactor shielding wall of a nuclear power plant,
The present invention relates to improvements in a reactor shielding wall that surrounds the outer periphery of a reactor pressure vessel installed in a reactor containment vessel and shields radiation from the core of the reactor pressure vessel.

[Technical background of the invention and its problems]

Generally, in a nuclear power plant, as shown in Figure 6, a reactor containment vessel (not shown) is installed in a reactor building (not shown).
PCV) 1.1, and this reactor containment vessel (
pCv)tl, the reactor pressure vessel (R)l! is mounted on the reactor pressure vessel pedestal 12! V) Stores E3. The outer periphery of the reactor pressure vessel [3 is surrounded by a reactor shielding wall (R3W) +5 erected on the pressure vessel pedestal 12 to shield radiation emitted from the core of the reactor pressure vessel 13. ing. In addition, in order to safely transfer the earthquake load from the reactor pressure vessel [3] to the reactor building structure [0] during an earthquake, the reactor pressure vessel [3]
A reactor pressure vessel stabilizer [6 is disposed between the reactor shielding wall [5] and the containment vessel [1], and a reactor containment vessel stabilizer [7] is disposed between the reactor shielding wall [5 and the containment vessel [1]. Furthermore, attached structures such as piping inside the reactor containment vessel 11 are also supported by the reactor shielding wall [5].

Therefore, the reactor shielding wall 15 itself is required to have a shielding function as well as strength and rigidity for load transmission. Specifically, as shown in FIG. The inner wall 21 and the stiffener connecting the inner wall 21 and the outer wall n are formed into a box shape that has a planar fan shape made of steel, and a concrete U is placed inside the box shape to ensure rigidity and shielding performance. It is made by fermenting the unit bodies filled with and combining the beauty of these unit bodies.

The reactor shielding wall [
The procedure for installing 5 will be explained below. That is, as shown in FIG. 7, first, before installing the reactor containment vessel 11,
A steel unit assembly is carried into the reactor containment vessel 11, and is placed on the pressure vessel pedestal L2 with the upper part open as if a tulip is blooming.
Next, the reactor pressure vessel [3 is carried from above to the area surrounded by each unit body and placed on the pedestal 12 as well.

When the reactor pressure vessel 13 is arranged in this way,
As shown in Figure 8, each unit body, which had been open in the shape of a tulip, is closed and fixed in place to surround the reactor pressure vessel [3], and the joints 6 of the steel parts of each unit body are closed to surround the reactor pressure vessel [3].
are connected by welding.

Then, concrete 24 is filled into the unit body which is the gap between the inner wall 21 and the outer wall n, and after curing, the reactor shielding wall 15' is completed by inspection. This is to carry out piping work inside the reactor containment vessel 11.

However, such work for installing the pressure vessel L3 and assembling the reactor shielding wall 15 is performed in a narrow space inside the reactor containment vessel 11, which is difficult to work in, and therefore takes much effort and time. Furthermore, in order to carry out welding, concrete 24 filling, and curing on site, it is necessary to consider sufficient preparations for quality control, which is also a critical path in the construction process, and improves work efficiency. Improvements were desired.

On the other hand, when a nuclear power plant reaches the end of its lifespan, the plant itself must be dismantled to decommission the reactor.
The dismantling work for the reactor shielding wall 5 at this time is thought to be as follows. In other words, at the end of blunt operation due to neutron irradiation from the reactor, the reactor shielding wall [5] itself has a high radioactivity level. It is planned that the detonation will be carried out by cutting or controlled detonation by remote control.

However, the reactor shielding wall L5 is a composite structure consisting of an S-class box-shaped unit body and a reactor IJ-) 24, and the reactor shielding wall L5 is located under radiation and in a narrow reactor containment vessel L5.
It is expected that the dismantling work will be difficult due to the fact that the work will be carried out within 100 meters, and it is desired to improve the efficiency of the dismantling work and reduce the burden on workers.

[Object of the Invention] Therefore, the present invention has been made in view of the above-mentioned circumstances, and provides a reactor shielding wall that facilitates work during construction and dismantling of the reactor shielding wall. The purpose is to

[Summary of the invention]

In order to achieve the above-mentioned object, one aspect of the present invention is that the reactor shielding walls surrounding the reactor pressure vessel have a predetermined shape when viewed from the side, are combined adjacent to each other, and are combined as a whole to form a reactor shielding wall. A divided block-like shielding ratio m is formed, and this shielding unit wall is provided with uneven share keys that fit into each other between adjacent ones in the circumferential direction and the vertical direction, and are arranged in combination. This system consists in fixing the shielding unit walls in the vertical direction with bolts and nuts or prestressed tendons, and has succeeded in facilitating the construction and dismantling of the reactor shielding walls themselves.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to FIGS. 1 to 5.

Reference numeral 1 in FIG. 1 indicates a block-shaped shielding wall assembly which is suitably divided so as to form a reactor shielding wall when assembled as a whole, and which have a predetermined shape when viewed from the side and are assembled adjacent to each other. As shown in FIG. 5, this shielding wall assembly 1 includes a steel box 2 that has a rectangular shape, a square rectangular shape, a concave shape, a convex shape, a parenthesis shape, a parenthesis shape, and other shapes when viewed from the side. It is made by filling the inside with concrete 3.

That is, in the present invention, conventionally, after assembling planar arc-shaped steel units into a cylindrical shape around the outer periphery of the reactor pressure vessel (3) on site, it is filled with concrete and allowed to cure on site. In contrast, the shielding wall assembly 1, which is divided into blocks and made of steel pockets 7.2 filled with concrete 3, is assembled on site. The concrete 3 to be filled should be thick enough to ensure radioactivity shielding.

As shown in FIG. 2, each shielding wall assembly 1 includes:
A concave-convex share key 4 is provided that fits into adjacent mutually in the circumferential direction and the vertical direction when combined, and this share key 4 is designed in consideration of regularity when combined. , one of the top and bottom surfaces is convex and the other is concave, and one of the left and right surfaces is convex and the other concave, so that when they are placed adjacent to each other, they fit in the concave-convex shape in a certain direction. . In addition, the convex share key 4 has a tapered tip compared to the base, and the concave 7 air key 4 has a deep part narrower than the opening, so that it can be easily fitted with uneven fittings. This is to ensure ease of operation and reliability of fitting.

Furthermore, in order to securely fix the shielding wall assembly 1 arranged in combination in the vertical direction, bolts and nuts 6 as shown in FIGS. 1 and 3 or as shown in FIG. 4 are provided.
Tighten with prestress tendon 7. Therefore, through-holes 5 are bored in the shielding wall assembly 1 at positions that correspond to each other in the vertical direction, and the through-holes 5 are defined as 1 in the pressure vessel in which the reactor shielding wall according to the present invention is installed. The bolt/nut 6 or prestress tendon 7 is inserted and fixed in the through hole 9 drilled in the pedestal I2, and the shielding wall assembly 1 is firmly connected and fixed to the pressure vessel pedestal 12. ing.

Reference numeral 8 in the figure is a pipe insertion part formed in the shield wall assembly l in a cutout shape and a bow shape in order to insert various pipes [8 of the reactor containment vessel [1], and corresponds to the connection position of the pipe [8]. The shielding wall assembly 1 is formed in advance.

Note that the number of divisions and the division shape of the shielding wall assembly 1 are not limited to the example shown in FIG.
connection, the capacity of the lifting machine, etc. during assembly, etc.
The most suitable one is selected arbitrarily.

In addition, since the joints along the vertical direction between the shield wall assemblies 1 arranged in combination are not straight, cracks that may occur along the vertical direction can be prevented, and similarly along the circumferential direction. Due to the fact that the seams are not straight, it is possible to prevent possible cracks from occurring in the circumferential direction.

Next, an example of a procedure for constructing a nuclear reactor shielding wall using divided block-shaped shielding wall assemblies 1 will be described. While fitting the uneven 7 air keys 4, they are assembled so that the whole is in a cylindrical shape surrounding the outer periphery of the pressure vessel E3 while being arranged adjacently in the vertical direction and the circumferential direction, and installed on the pressure vessel pedestal [2]. Next, the vertically arranged shielding wall assembly 1 is integrally fixed with the pressure vessel pedestal 12 using bolts and nuts 6 or prestressed tendons 7.

〔Effect of the invention〕

Therefore, according to the present invention, the cylindrical locking body surrounding the outer periphery of the reactor pressure vessel is divided in the circumferential direction and the vertical direction to form the block-shaped shielding wall assembly. Regardless of when the container is installed, each assembly can be carried in separately, making it easy to install, and efficiently connecting piping and attaching other attached structures. In addition, this method is extremely efficient compared to the conventional method, which required transporting each unit into the reactor containment vessel before installing the reactor pressure vessel [3], which resulted in poor work efficiency. This means that the work can be carried out quickly. Moreover,
Compared to the conventional example where conocrete was filled on-site, the present invention allows the shielding wall assembly to be filled with concrete at a factory, so filling and curing of concrete on-site can be omitted, and quality control can be ensured. You can also do it.

In addition, since the vertically arranged shielding wall assemblies are fixed with bolts and nuts or prestressed tendons, tightening is restricted in the vertical direction, ensuring rigidity and safely handling various loads. It can be transmitted to building structures.

Furthermore, since the shielding wall assembly is provided with uneven share keys that fit into each other between adjacent ones in the circumferential direction and the vertical direction, the whole assembly is firmly assembled when placed adjacently and assembled. It is extremely sturdy and safe, as it will not be disassembled into individual units due to shock, vibration, etc.

On the other hand, in the conventional structure, radioactive waste is scattered during disassembly, which causes many problems in terms of radiation control.In contrast, in the present invention, the shielding wall assembly assembled in a block shape is By removing the bolts and nuts or prestressed tendons that fix these, each block-shaped shielding wall assembly can be dismantled and removed. Therefore, radioactive waste can also be disposed of in individual units, making dismantling work easier, reducing radiation exposure for each worker, and shortening the dismantling process. This can be expected to be reduced.

[Brief explanation of the drawing]

1 to 5 show one embodiment of the present invention, FIGS. 1(A) and 5(B) are exploded perspective views of the reactor shielding wall, and FIG. 2 is a part of the main part of the shielding wall assembly. 3 and 4 are perspective views after assembly, FIG. 5 is a partially developed view of the side of the assembled nuclear reactor shielding wall, and FIG. 6 is a typical nuclear reactor shielding wall. 7 and 8 are perspective views showing a conventional example. 1... Shielding assembly, 2... Steel box, 3... Concrete% 4... Share key, 5... Penetration hole, 6
... Bolt/nut, 7... Prestress tendon, 8... Piping insertion part, 9... Penetration hole, [0... Building structure, 11... Reactor containment vessel %12 ... Reactor pressure vessel pedestal, [3... Reactor pressure vessel, [
4...F core% 15...Reactor shielding wall, 16...Reactor pressure vessel stabilizer 2 isa, 17...Reactor containment vessel stabilizer, I8...Piping, 20 City unit, 21
...Inner wall, 22-mount outer wall, 23-mount stiffener - 1M.
・Concrete, 25 joints. Applicant's agent Hisashi Hatano Figure 1 Figure 2 Figure 5 Figure 7 Figure 8

Claims (1)

[Scope of Claims] 1. In a reactor shielding wall that surrounds the outer periphery of a reactor pressure vessel with a cylindrical shielding wall body, the cylindrical shielding wall body is divided into circumferential and vertical directions to form shielding walls. A retaining portion for connecting the shield wall assemblies to each other is formed at the connecting end of each shield wall assembly, and the shield wall assembly is connected to the reactor through these retaining portions. A nuclear reactor shielding wall, characterized in that it is stacked in a cylindrical shape around the outer periphery of a pressure vessel, the six shielding wall assemblies are vertically fastened to each other using fasteners, and are fixed to a mounting table. 2. The reactor shielding wall according to claim 1, wherein the shielding wall assembly is formed by filling a steel box with concrete. 3. The reactor shielding wall according to claim 1, wherein the mounting table is a pressure vessel pedestal on which the reactor pressure vessel is placed. 4. The reactor shielding wall according to claim 1, wherein the retaining portion is a share key having an uneven shape. 5. The reactor shielding wall according to claim 1, wherein the shielding wall assemblies are assembled so that vertical seams between the shielding wall assemblies are non-linear. 6. The reactor shielding wall according to claim 1, wherein the shielding wall assemblies are assembled so that circumferential joints between the shielding wall assemblies are non-linear. 7. The reactor shielding wall according to any one of claims 1 to 4, wherein the shielding wall assembly has a pipe insertion portion formed in a cutout shape or a bow shape.