JPH0363607B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of constructing a lower pedestal for supporting a pressure vessel of a nuclear reactor, particularly a boiling water reactor.

[Technical background of the invention]

A conventional construction method for a lower pedestal supporting a pressure vessel of a boiling water reactor will be explained with reference to FIG.

At the bottom of the lower pedestal 1, three annular ring girders 2, 3, and 4 with different diameters are arranged horizontally and concentrically on the inside and outside, and the ring girders 2, 3, and 4 have the following structure:
A large number of rod-shaped reinforcing bars 5 are connected at their lower ends in two rows, one inside and one outside, standing upright on the circumference, and each row of reinforcing bars 5 has circles with different diameters arranged horizontally and concentrically at seven locations spaced apart in the vertical direction. Circular reinforcing bar 6 or 1
1 are combined. Innermost and outermost reinforcing bars 5,
6, 5, 11, an inner lining 12 and an outer lining 13 made of steel cylinders are installed upright on the inner and outer sides.
By filling the gap and placing concrete 14, the lower pedestal 1, which is a reinforced concrete cylinder, is formed. An intermediate slab 15 is constructed at the upper end of the lower pedestal 1, an upper pedestal 16 is constructed on the intermediate slab 15, and the lower pedestal 1 is constructed from the intermediate slab 15 and the upper pedestal 16.
A pressure vessel (not shown) is supported via.

To construct the lower pedestal 1, first, the ring girders 2, 3, and 4, with the multiple stud dowels 17 fixed to each of them facing downward and vertically, are placed inside and outside on the pre-cast concrete foundation. Install concentrically and horizontally. Concrete is placed below and around the ring girders 2, 3, 4 to fix the ring girders 2, 3, 4 and to construct a horizontal floor 18. The upper halves of the ring girders 2, 3, 4 are exposed on the horizontal floor 18. A partition floor 19 is provided horizontally at a distance slightly outward from the outer ring girder 4 and above the horizontal floor 18. Construction scaffolding 20 for assembling reinforcing bars is assembled in place on partition floor 19. The construction scaffolding 20 is used as needed for the following construction work. The reinforcing bars 5 in the inner first row are assembled upright by screwing their lower end threaded parts into screw holes provided in the inner ring girder 2 at equal pitches on the circumference. Next, the inner lining 12 is installed upright on the horizontal floor 18 inside the ring girder 2 and concentrically therewith. A large number of stud bolts (not shown) are fixed to the inner lining 12 in multiple rows in the vertical direction, protruding radially from the outer periphery of the lower half, and lower pedestals are fixed to the inner lining 12 at two equal quarter positions on the circumference in the plane in the vertical direction. A cylindrical sleeve 21 having a length approximately equal to the thickness of the peripheral wall of the inner lining 1 is inserted and fixed to protrude radially from the outer periphery, but when installing the inner lining 12, the stud bolts and the sleeve 21 do not interfere with the reinforcing bar 5. The relative positions of the reinforcing bars 5 and the inner lining 12 are adjusted so that they pass through the gaps between the reinforcing bars 5. The reason why the reinforcing bars 5 in the first inner row are assembled before installing the inner lining 12 is that the reinforcing bars 5 are located close to the location where the inner lining 12 is installed.
This is because reinforcing is difficult. Next, annular reinforcing bars 6 are sequentially assembled from the bottom to the top at seven locations in the vertical direction of the reinforcing bars 5 in the inner first row. Next, the reinforcing bars 5 and 7 to 11 are assembled sequentially from the inside to the outside and from the bottom to the top in the same manner as the reinforcing bars 5 and 6 in the first inner row. Next, the outer lining 13 is installed upright on the horizontal floor 18 outside the first row of reinforcing bars 5 and 11 on the outer side and concentrically with the ring girder 4. The outer lining 13 consists of upper and lower halves, which are divided into 8 equal parts in the circumferential direction, and a large number of stud bolts (not shown) are fixed to the inner periphery of the lower half toward the center. A hole having a diameter through which the sleeve 21 can be inserted is bored at a position corresponding to the outer end of the sleeve 21 fixed to the lining 12. The lower half of the outer lining 13 is first placed on the horizontal floor 18, the upper half is placed on top of it, and all the mating surfaces of the 8 divided parts are welded together to make one piece. Next, a plurality of embedded metal fittings 22 that serve as attachment seats for accessory structures are welded and fixed to the outer circumferential surface of the outer lining 13, and the outer ends of each of the sleeves 21 are welded and fixed to the outer lining 13. By pouring and filling concrete 14 between the inner lining 12 and the outer lining 13, the lower pedestal 1, which is a reinforced concrete cylinder, is formed. In parallel with the construction of the lower pedestal 1, a bottom liner 23 is laid on the upper surface of the horizontal floor 18. Lower pedestal 1
The construction work and the laying work of the bottom liner 23 are vertical work.

[Problems with background technology]

In the conventional construction method of the lower pedestal, the outer lining 13 is divided into 8 parts, which are assembled and welded together at the installation site, and the embedded metal fittings 22 are welded and fixed to the outer periphery of the outer lining 13, which requires a large number of man-hours at the site. Therefore, there is a disadvantage that the construction period of the lower pedestal 1 is longer.
Since the construction work and the laying work of the bottom liner 23 involve vertical work, there is a problem in terms of construction safety, and there is also a drawback that the complicated construction work may cause delays.

[Purpose of the invention]

This invention was made in order to solve the above-mentioned problems of the conventional construction method of the lower pedestal.
This reduces the number of man-hours required for on-site installation of the outer lining, thereby shortening the construction period for the lower pedestal.Furthermore, external work such as laying the bottom liner can be carried out safely regardless of the construction work for the lower pedestal, contributing to shortening the construction period. The purpose of this invention is to provide a method for constructing a lower pedestal.

[Summary of the invention]

The method for constructing the lower pedestal according to this invention is as follows:
The inner periphery of the reactor pressure vessel is covered with an inner lining and an outer lining of a steel cylinder, and a plurality of annular ring girders with different diameters are arranged horizontally and concentrically at the bottom of the reactor pressure vessel, forming an upright reinforced concrete cylinder. In the supporting lower pedestal, the outer lining and inner lining are formed in advance as described below, and the construction is carried out in the following order to achieve the above purpose.

The outer lining is preliminarily fixed with stud bolts protruding toward the center at each of a plurality of specific locations on the inner periphery of the lower half, and a cylinder having a length approximately equal to the wall thickness of the cylindrical body is attached to each of the plurality of specific locations on the inner periphery. A shaped sleeve is inserted through and protrudes toward the center and is fixed thereto, and a plurality of embedded metal parts are fixed to the outer periphery with at least one surface thereof exposed to form an integral structure.

The inner lining is divided into upper and lower halves, and a number of stud bolts are fixedly protruding radially from the outer periphery of the lower half. A hole is bored at a position corresponding to the inner end of the sleeve secured to the outer lining and has a diameter that allows the sleeve to pass therethrough.

Construction of the lower pedestal will be carried out in the following order.

At the bottom of the lower pedestal, multiple ring girders are installed horizontally in a concentric circle and fixed with concrete, and a horizontal floor is constructed around them. Assemble construction scaffolding at a little distance inside the ring girder. This construction scaffolding will be used as needed to proceed with the following construction work. Install the outer lining upright on the outer horizontal floor concentric with the ring girder. Leaving the first row of reinforcing bars on the inside, a large number of vertical reinforcing bars are installed inside the outer lining in multiple concentric rows with the lower end connected to the ring girder, and connected to the bar reinforcing bars in each row to form multiple upright bars in the vertical direction. Assemble circular reinforcing bars horizontally at the location from outside to inside and from bottom to top. Inside the ring girder, outside the construction scaffolding,
Install the lower half of the inner lining upright and concentric with the outer lining. Assemble the bar-shaped reinforcing bars and circular reinforcing bars in the first inner row. The upper half of the inner lining is centered over the lower half, the mating surfaces are welded, and the free ends of each sleeve are welded to the inner lining. Complete the construction of the lower pedestal by filling and pouring concrete between the inner lining and outer lining.

[Embodiments of the invention]

An embodiment of the invention will be described with reference to FIG. Parts shown in FIG. 2 that are equivalent to those shown in FIG. 1 will be given the same reference numerals as in FIG. .

Lower pedestal 3 constructed according to this invention
0, the inner periphery and outer periphery of the steel cylinder are respectively covered with an inner lining 32 and an outer lining 33, and the bottom part is covered with 3
The structure of the upright reinforced concrete cylinder in which the ring girders 2, 3, and 4 are arranged is similar to the structure of the lower pedestal 1 constructed by the conventional construction method.

The inner lining 32 is initially divided into upper and lower halves, and a large number of stud bolts 34 are fixed in advance to the outer periphery of the lower half, projecting radially in seven rows in the vertical direction. The outer lining 33 is integrally formed, and a large number of stud bolts 35 are fixed in advance to the inner periphery of its lower half in seven rows in the vertical direction, protruding toward the center. Cylindrical sleeves 21 having a length approximately equal to the thickness of the cylindrical body wall of the lower pedestal 30 are inserted and fixed in advance to a total of eight separate locations, and protrude toward the center.
A plurality of embedded metal fittings 22 forming attachment seats for ancillary structures
is fixed in advance with at least one surface exposed.

To construct the lower pedestal 30, first,
Annular ring girders 2 having different diameters each having a large number of stud dowels 17 fixed thereto,
3 and 4 are installed horizontally and concentrically on a pre-cast concrete foundation with the stud dowel 17 facing downward, concrete is poured below and around it, and the ring girders 2, 3, and 4 are fixed. Build a horizontal floor 18. At that time, the upper halves of the ring girders 2, 3, 4 are exposed on the horizontal floor 18. Next, a construction scaffold 20 is erected on the horizontal floor 18 at a little distance inside the inner ring girder 2. The construction scaffolding 20 is used whenever necessary for the construction work to be described later. Next, the outer lining 33 is installed upright on the horizontal floor 18 outside the outer ring girder 4 and concentrically with the ring girder 4. Next, the lower end threaded portions are screwed into the screw holes provided concentrically in two rows of inner and outer rows at equal pitches in the circumferential direction at the upper end of each of the ring girders 2, 3, and 4. The circular reinforcing bars 11 to 7 are assembled in five upright rows in a concentric cylindrical space from the outside to the inside, and the annular reinforcing bars 11 to 7 are placed at seven locations in the vertical direction of the bar-shaped reinforcing bars 5 in each row from the outside to the inside. Assemble them horizontally and concentrically upwards. Next, the lower half of the inner lining 32 is installed upright on the horizontal floor 18 inside the ring girder 2 and concentrically with it, and then the remaining reinforcing bars 5 and 6 of the inner first row are placed, and then the inner lining The upper half of 32 is aligned and rested on its lower half. When installing the lower half and upper half of the inner lining 32, the sleeves 2 are pre-drilled in the inner lining 32 in correspondence with the free end positions of the sleeves 21 fixed to the outer lining 33.
The inner lining 3 is arranged such that each free end of the sleeve 21 looks into a hole of a diameter that allows the sleeve 21 to pass through the inner lining 3.
Adjust the installation position of 2. Next, the lower half and upper half of the inner lining 32, the free ends of the sleeves 21, and the inner lining 32 are welded together, concrete 14 is cast and filled between the inner lining 32 and the outer lining 33, and construction work is carried out. scaffolding 2
By completely removing 0, construction of the lower pedestal 30 is completed.

〔Effect of the invention〕

The method for constructing the lower pedestal according to this invention is as follows:
The outer lining that covers the outer periphery of the lower pedestal is formed integrally from the beginning, and the embedded hardware is fixed to the outer periphery in advance, so the eight parts of the outer lining can be assembled and welded together at the installation site using conventional construction methods. Compared to the case where embedded hardware is fixed, even though the conventionally integrated inner lining is divided into two parts in the case of the present invention, the total installation man-hours including welding of the outer lining and inner lining are greatly reduced, and the construction of the lower pedestal is simplified. This has the effect of significantly shortening the construction period, and since the construction work is carried out from the inside using the construction scaffolding assembled inside the lower pedestal, the work outside the lower pedestal is obstructed by the lower pedestal construction work. This has the effect of shortening the construction period because the work can be done in parallel without having to worry about any problems.Furthermore, the installation work of the bottom liner on the horizontal floor outside the lower pedestal and the construction work of the lower pedestal can be done up and down and become complicated. This has the effect of improving construction safety and shortening the construction period.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a lower pedestal of a reactor pressure vessel constructed using a conventional construction method, and FIG. 2 is a longitudinal cross-sectional view of the lower pedestal constructed using a construction method according to the present invention. 2, 3, 4...Ring girder, 5...Bar-shaped reinforcing bar, 6
~11...Circular reinforcing bar, 14...Concrete, 18
...Horizontal floor, 20...Scaffolding for construction, 21...Sleeve,
22...embedded hardware, 30...lower pedestal, 32...
Inner lining, 33...Outer lining, 34,
35... Stud bolt.

Claims (1)

[Scope of Claims] 1. A lower pedestal having an upright reinforced concrete cylinder whose inner periphery is covered with an inner lining and an outer lining of a steel cylinder and which supports a reactor pressure vessel has a plurality of pedestals with different diameters at the bottom part thereof. Annular ring girders are arranged horizontally and concentrically inside and outside, concrete is poured below and around the ring girders to expose the top surface of the ring girders and fix them, and a horizontal floor is constructed around the ring girders,
A construction scaffold is erected inside the ring girder at the innermost position on the horizontal floor, and this construction scaffold is used as needed to install the outer ring girder at the outermost position on the horizontal floor concentrically with the outer ring girder. The lining is installed upright, and then the lower end is connected to the ring girder, and a large number of rod-shaped reinforcing bars are installed in multiple rows upright along multiple cylindrical spaces almost concentrically with the ring girder, leaving the innermost row on the outside. In parallel with this reinforcement, from below to above, circular reinforcing bars are connected to the reinforcing bars in each of the inner and outer rows in a substantially concentric circle, and circular reinforcing bars are sequentially arranged horizontally at multiple locations in the vertical direction. Next, the lower half of the inner lining, which is divided into two upper and lower halves, to which a large number of stud bolts protrude radially from the outer periphery and are fixed, is placed concentrically with the innermost ring girder and inside of the construction scaffold. The upper half of the inner lining is placed vertically on the horizontal floor on the outside, and then, after placing the remaining innermost row of bar reinforcing bars and circular reinforcing bars, the upper half of the inner lining is centered over the lower half. The reactor pressure vessel is constructed by placing them together and welding the joint parts of the upper and lower halves, and then pouring and filling concrete between the outer lining and the inner lining, and then removing the construction scaffolding. Construction method of lower pedestal. 2. Stud bolts are fixed to the outer lining in advance at a plurality of specified locations on the inner periphery of the lower half of the lining, protruding toward the center at each of the plurality of specified locations on the inner periphery, and stud bolts protruding toward the center at each of the plurality of specified locations on the inner periphery and having a wall thickness approximately equal to the wall thickness of the cylindrical body. Insert and secure the length of the cylindrical sleeve,
2. The method of constructing a lower pedestal for a nuclear reactor pressure vessel according to claim 1, wherein a plurality of embedded metal objects are fixed in advance to the outer periphery of the outer lining with at least one surface exposed.