JPH06294888A - Support pedestal for reactor pressure vessel - Google Patents

Abstract

PURPOSE:To provide a support pedestal for a reactor pressure vessel can minimize the welding work on the spot to shorten the time for installing and enable the improvement of manufacturing precision. CONSTITUTION:The whole body of a support pedestal 2 for a reactor pressure vessel is a hollow cylinder, and the main body consists of multiplex cylindrical steel plates 6. A vent pipe S is contained between them and the clearance between them is filled with concrete 7. In such a support pedestal 2 for a reactor vessel, multiplex cylindrical steel plates 6consist of three vertically divided blocks 1), 2) and 3). On the boundary of these blocks lie flanges 10 with a horizontal boundary surface. The flanges are connected to each other with a high strength bolt 12 and the boundary surface between adjacent flanges is welded with seal 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support pedestal of a reactor pressure vessel, and more particularly to a structure of a pedestal in a concrete reactor containment vessel.

[0002]

2. Description of the Related Art A concrete containment vessel for a boiling water reactor (BWR) is a facility for safely and hermetically containing a reactor pressure vessel (hereinafter simply referred to as "reactor"). For example, as shown in FIG. It consists of dry wells 3a and 3b in which the reactor 1 is installed on the pedestal 2, and a suppression chamber 4 which communicates with the dry well and has a large amount of water W inside. The dry well contains the upper half of the reactor 1. And an upper drywell 3a for storing the lower half of the reactor. The pedestal 2 that supports the reactor 1, that is, the pedestal 2 supports the reactor 1 and transmits its weight to the building below, and also has a vent pipe 5 built-in, so that high temperature steam is blown out from the reactor 1 due to an accident or the like. The steam is introduced into the water W (suppression pool) in the suppression chamber 4 through the vent pipe 5 to condense the steam and suppress the pressure increase in the storage container. A pedestal 2 of a conventional reactor pressure vessel is, for example, as shown in FIG. 2, a hollow cylindrical body having an inner diameter of about 10 m, an outer diameter of about 14 m, and a height of about 20 m. The vent pipe 5 is built in between, and the gap is filled with concrete 7.
The nuclear reactor 1 is supported by the supporting portion 6a, and its weight is transmitted to the lower building through the double cylindrical steel plate 6. In addition, a plurality of communication ports 8 are provided in the upper part of the vent pipe 5 so that the upper and lower dry wells 3 a and 3 b communicate with each other and the upper and lower dry wells 3 a and 3 b communicate with the vent pipe 5.

[0003]

The conventional pedestal has the following problems.
It is vertically divided into five blocks shown by in FIG. 2 and the first block is divided into three blocks in the circumferential direction.
It was divided into four parts, and each connection was done by field welding.
However, the amount of welding in this field welding is large (for example, 6
Because of the large amount of welding work, it takes time to install, and a large temporary scaffold etc. is required for this on-site welding.
Further, there is a problem that the manufacturing accuracy is apt to deteriorate due to the on-site welding. The present invention was created to solve such problems. That is, an object of the present invention is to provide a support pedestal for a reactor pressure vessel that can minimize on-site welding, thereby shortening the installation time and improving the manufacturing accuracy. .

[0004]

According to the present invention, the whole is a hollow cylinder, the main body is made of double cylindrical steel plates, the vent pipe is built in between, and the gap between them is filled with concrete. In a support pedestal of a reactor pressure vessel, the double cylindrical steel plate is composed of a plurality of blocks divided in the vertical direction, and a boundary portion of the plurality of blocks has a flange having a horizontal boundary surface. Are connected to each other by high-strength bolts, and the boundary surfaces of adjacent flanges are seal-welded, and a support pedestal for a reactor pressure vessel is provided.

[0005]

According to the above-mentioned structure of the present invention, the double cylindrical steel plate is composed of a plurality of vertically divided blocks, and a flange having a horizontal boundary surface is provided at a boundary portion of the plurality of blocks. Since the flanges are connected to each other by high-strength bolts and the boundary surfaces of the adjacent flanges are seal-welded, the field welding is only seal welding, and the welding operation can be almost eliminated. Also, since there is almost no on-site welding, and the horizontal boundary surfaces of the flanges are aligned and connected to each other by high-strength bolts, a large temporary scaffold is not required, and manufacturing accuracy can be improved, and installation time can be improved. It can be shortened.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional view of a support pedestal of a reactor pressure vessel according to the present invention. In this figure, the support pedestal of the reactor pressure vessel of the present invention also has a hollow cylindrical shape as in the conventional case, the main body is constituted by the double cylindrical steel plate 6, and the vent pipe 5 is built in between them. The gap is filled with concrete 7.

According to the present invention, the double cylindrical steel plate 6 is composed of three blocks, which are divided in the vertical direction,
A flange 10 having a horizontal boundary surface is provided at a boundary portion of the three blocks. Each of the three blocks is integrated and has a weight that can be lifted by a crane, for example, within 500 tons. As a result, at the installation site, each block can be hoisted in order by a crane and installed at the site. The boundary surfaces of the flange 10 are processed with sufficient accuracy so that they can be assembled with high accuracy by closely contacting each other.

At the installation site, the block,
Are sequentially installed, the flanges 10 are connected to each other by high-strength bolts 12 (and nuts), and then a seal welding 14 is performed on the boundary surface of the adjacent flanges. The high-strength bolt 12 and nut are bolts and nuts with high tensile strength,
The force acting on the flange 10 can be transmitted by the friction between the flanges and the tension generated in the bolt. The seal welding 14 completely welds the entire circumference in order to prevent water in the suppression chamber 4 adjacent to the outer peripheral portion of the pedestal 2 from leaking to the lower dry well 3b. With this configuration, there is almost no on-site welding, just by connecting the horizontal boundary surfaces of the flanges and connecting them with each other with high strength bolts,
Installation can be performed with high manufacturing accuracy and in a short time.

[0009]

As described above, according to the present invention, the double cylindrical steel plate is composed of a plurality of vertically divided blocks, and a flange having a horizontal boundary surface at the boundary portion of the plurality of blocks. , The flanges are connected to each other by high-strength bolts, and the boundary surfaces of adjacent flanges are seal-welded, so the field welding is seal welding only,
Welding work can be almost eliminated. Also, since there is almost no on-site welding, and the horizontal boundary surfaces of the flanges are aligned and connected to each other by high-strength bolts, a large temporary scaffold is not required, and manufacturing accuracy can be improved, and installation time can be improved. It can be shortened.

The present invention therefore minimizes field welding, which reduces installation time and
Moreover, it has an excellent effect that the manufacturing accuracy can be improved.

[Brief description of drawings]

1 is a partial cross-sectional view of a support pedestal of a reactor pressure vessel according to the present invention.

FIG. 2 is an overall sectional view of a support pedestal of a conventional reactor pressure vessel.

FIG. 3 is an overall view of a concrete containment vessel for a boiling water reactor (BWR).

[Explanation of symbols]

 1 Reactor 2 Pedestal (support pedestal) 3a Upper drywell 3b Lower drywell 4 Suppression chamber 5 Vent pipe 6 Double cylindrical steel plate 7 Concrete 8 Communication port 10 Flange 12 High-strength bolt 14 Seal welding ..., Block W Water

Claims (1)

[Claims] 1. A support pedestal of a reactor pressure vessel, wherein the whole is a hollow cylinder, a main body is made of a double cylinder steel plate, a vent pipe is built in between, and a gap between them is filled with concrete. The double cylindrical steel plate is composed of a plurality of blocks divided in the vertical direction, has a flange having a horizontal boundary surface at the boundary portion of the plurality of blocks, the flanges are connected to each other by a high-strength bolt, and A support pedestal for a reactor pressure vessel, characterized in that the interface between adjacent flanges is seal welded.