JPS5870195A - Diaphragm floor of reactor container - 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 The present invention relates to a diaphragm floor of a nuclear reactor containment vessel.
In particular, the present invention relates to a diaphragm floor for a nuclear reactor containment vessel, which can improve the heat insulation effect, and by making the diaphragm floor made of steel, can simplify assembly work and greatly shorten the construction period.

Generally, as a nuclear reactor containment vessel, a reactor containment vessel 1 shown in FIG. 1, which is commonly referred to as a MARK-II type, is known. The containment vessel 1 is formed into a cylindrical shape with a bottom and a substantially conical upper part, and a pedestal 3 that supports the reactor pressure vessel 2 is erected at the center thereof. The inside of this containment vessel 1 is airtightly divided vertically by a diaphragm floor 6 into a dry well 4 that accommodates the reactor pressure vessel 2 and a subregion chamber 5 that suppresses the pressure inside this dry well 4. In addition, in preparation for an accidental failure of the cooler in the dry well 4, the air-water mixture generated at this time is guided into the cooling water W in the subregion chamber 5 through the vent pipe 7. Here, by cooling and condensing, it is possible to suppress the pressure increase in the dry well 4.

By the way, the diaphragm floor 6 needs to be firmly assembled so as to be able to withstand the large pressure difference that will occur between the dry well 4 and the subregion chamber 5 in the event that the coolant in the dry well 4 is lost. Therefore, it is constructed of steel and concrete as shown in Figure 2. That is, the diaphragm floor 6 is provided between the inner wall 1a of the containment vessel 1a and the pedestal 3 at appropriate intervals along their circumferential directions, and
A beam 9 supported by a column support 8 erected from the bottom of the beam 9 and a horizontal beam 9a connecting them are mainly used. After a seal plate 10 is stretched on this beam, a second The whole structure is constructed by first insulating concrete 11 and strong reinforced concrete slab 12 being poured, and finally, second insulating concrete 13 is sequentially laminated.

The rigidity of the beam 9, the horizontal beam 9a, and the reinforced concrete slab 12 makes it possible to withstand the differential pressure generated between the dry well 4 and the subregion chamber 5 in the event of an accident as described above.

In addition, 14 is the containment vessel inner wall 1a and the diaphragm floor 6.
It is an annular seal bellows provided along the circumferential direction between the peripheral edge of the

However, in such a structure, in order to prevent the strength of the reinforced concrete slab 12, which is weak against heat, from deteriorating due to heat transfer from the dry well 4 side, second insulating concrete is installed above and below the reinforced concrete slab 12. 13 and the first insulating concrete IJ-) 11 are required, as well as a seal plate 10 for pouring these concretes, making the construction work complicated.

In addition, the first and second insulating concrete 11.13
They also have the function of insulating the space between the dry well 4 and the subregion chamber 5, but since a large load is applied to them, they must be formed with a certain level of strength. Therefore, it has been difficult to create a structure that sufficiently functions as the above-mentioned heat insulating material.

Furthermore, in the above-mentioned concrete work, a series of operations such as reinforcing reinforcement, pouring, and curing must be performed, and especially if the last step, concrete curing, is not performed sufficiently, the next work step, pipe hoisting, must be carried out. It was not possible to move on to the installation work of the structures inside the dry well such as the tube structure, which forced the assembly work of the diaphragm floor 6 to take a long time and the construction period of the entire nuclear facility accordingly to be extended.

Furthermore, with the concrete diaphragm floor 6, deterioration cannot be avoided due to long-term use, resulting in problems such as cracks, etc., deteriorating the health of the nuclear facility. Man.

The present invention has been devised in order to effectively solve the above-mentioned problems, and its purpose is to improve the heat insulation effect and to improve the diaphragm floor made of steel. It is an object of the present invention to provide a diaphragm floor for a nuclear reactor containment vessel, which can simplify assembly work and greatly shorten the construction period.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, as shown in FIGS. 3 and 4, 3 is a cylindrical pedestal erected at the center of the reactor containment vessel 1 to support the reactor pressure vessel. A diaphragm floor 15, which is a feature of the present invention, is provided between the pedestal 3 and the inner wall 1a of the containment vessel 1, and the interior of the containment vessel 1 is
It is divided into a dry well 4 that accommodates the reactor pressure vessel and a subregion chamber 5 below this. To explain this specifically, the beam body 16 constituting the diaphragm floor 15 is made of H-beam steel, and one end 16a of this body is supported by the mounting part 3a of the pedestal 3, and the other end 16b is attached to the inner wall 1a of the containment vessel with a bracket 11. These pedestals 3 and the containment vessel 10 are radially disposed at appropriate intervals along the circumferential direction. These beam bodies 16 are column supports 8 erected at the bottom of the containment vessel 1.
is definitely supported. And, between these beam bodies 16, cross beams 18 are arranged at appropriate intervals along the radial direction of the containment vessel 1, and each beam body 1
6 is welded and fixed. Furthermore, these cross beams 18...
Auxiliary #s, 19, etc., arranged at appropriate intervals along the longitudinal direction, are passed between each other, and each is welded and fixed to the cross beam 18, forming the entire frame C. There is.

A thick steel plate floor 20 of approximately 40 m1 is disposed on the frame C or the beam body 1-6 to form a sealed compartment in the containment vessel 1 into the dry well 4 and the subregion chamber 5.
are integrally welded and fixed, and the rigidity of this steel plate floor 20 and the frame C or the beam body 16 can withstand the differential pressure between the dry well 4 and the subregion chamber 5 that would occur in the event of an accident. It looks like this. And this steel plate floor 2
The inner wall 1 of the containment vessel is attached along the circumferential direction of the periphery of the container 0.
An annular seal bellows 14 is formed between the dry well 4 and the subregion chamber 5 to reliably block air convection between the steel plate floor 20 and the dry well 4 and the subregion chamber 5. ing.

On the other hand, a heat insulating layer 22 is formed in the lower part of the beam body 16 and the frame C to ensure insulation between the dry well 4 and the sub-region chamber 5, and this installation work is performed on the steel plate floor 20. This will be carried out at the same time as the welding work. Specifically, the heat insulating layer 22 is made of, for example, asbestos, and is stretched over the entire lower surface of the upper beam body 16 to the frame C. Note that since no load is applied to this heat insulating layer 22, a material with good heat insulating efficiency is selected regardless of its strength.

The diaphragm floor 15 constructed in this way is penetrated by the dry well 4 and the subregion chamber 5.
A vent pipe 21 extending into the cooling water W inside is appropriately provided.

In the diaphragm floor 15 configured in this way, in the event of an accident, a mixture of air and water will be generated in the dry well 4, and a large pressure difference will be generated between the interior of the dry well 4 and the subregion chamber 5. This differential pressure can be withstood by the rigidity of the beam body 16 or frame C and the thick steel plate floor 20.

Also, a steel plate floor 20 integrally welded to the upper surface of the frame C, and a peripheral portion 20 of the steel plate floor 20. The seal bellows 14 is installed along the top of the drum.

The space between the well 4 and the subregion chamber 5 is completely sealed to block air convection between them, and the lower part of the beam body 16, that is, the diaphragm floor 1
Since a heat insulating layer 22 with good heat insulating efficiency is formed on the entire lower surface of the dry well 5, the heat insulating effect between the dry well 4 and the subregion chamber 5 can be improved.

In addition, since the heat insulating layer 22 is installed on the lower surface of the beam body 16 or the frame C, the installation work of the heat insulating layer 22 is carried out simultaneously with the welding work of the steel plate floor 20 attached to the upper part of the frame C. - It is possible to shorten the construction period. Furthermore, since the diaphragm floor 15 is made of steel, concrete work that was previously required, that is, reinforcement,
Pouring and curing can be made unnecessary. In particular, since there is no longer a need for concrete curing, installation work for structures inside the drywell, such as pipe whip structures, can be started immediately after the assembly of the diaphragm floor 15 is completed, and therefore construction of nuclear facilities can be started immediately. The construction period can be drastically shortened.

In short, according to the present invention, the following excellent effects can be achieved.

(1) Making the diaphragm floor made of steel eliminates the need for conventional concrete work, that is, a series of time-consuming tasks such as reinforcing, pouring, and curing, and simplifies assembly work.

(2) In on-site construction, there is no need to adjust the timing of steel structure construction and concrete construction, and construction management and schedule management can be easily performed.

(3) In particular, since there is no longer a need for concrete curing, immediately after the diaphragm floor assembly is completed,
Can Shigeko immediately begin construction work inside the drywell (4) Pipe Whips)? Since the internal structure of the dry well, such as the structure, can be fixed directly to the steel plate floor, the connecting structure can be simplified and rationalized.

(5) The welding work of the steel plate floor and the installation work of the heat insulation layer can be performed simultaneously.

(6) Therefore, for the reasons stated above, the construction period for nuclear facility construction can be significantly shortened.

(7) By forming an airtight partition between the dry well and the subregion chamber with a thick steel plate floor, air convection between them is blocked, and a heat insulating layer is formed on the underside of the diaphragm floor. , the heat insulation effect can be improved as much as possible.

(8) Unlike conventional concrete diaphragms, there is no risk of deterioration and cracking, and the health of nuclear facilities can be improved as much as possible.

(9) Since the structure is simple, it can be easily adopted without making any major changes to the conventional design.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the inside of the reactor containment vessel, FIG. 2 is a longitudinal sectional view showing a conventional diaphragm floor of the reactor containment vessel, and FIG. 3 is a partially cutaway view showing a preferred embodiment of the present invention. ,
FIG. 4 is a longitudinal sectional view of the same. In addition, in the figure, 1 is the reactor containment vessel, 1a is the inner wall of the containment vessel,
2 is a reactor pressure vessel, 3 is a pedestal, 4 is a dry well, 5 is a subregion chamber, 15 is a diaphragm floor, 16 is a beam body, 20 is a steel plate floor, and 22 is a heat insulating layer. Patent Applicant: Nobuo Kinutani, Patent Attorney, Ishikawajima-Harima Heavy Industries Co., Ltd.

Claims (1)

[Claims] Inside the reactor containment vessel, which has a pedestal erected in the center to support the reactor pressure vessel, is a dry well that accommodates the reactor pressure vessel, and a subregion chamber that suppresses the pressure within the dry well. In the diaphragm floor, which is divided into two sections, a steel beam is provided between the inner wall of the containment vessel and the pedestal, and a steel beam is integrally welded and stretched over the beam. A steel plate floor for blocking air convection between the well and the sub-region chamber and forming a sealed compartment therebetween, and a floor made of a steel plate formed at the lower part of the beam body to insulate the space between the dry well and the sub-region chamber. A diaphragm floor for a nuclear reactor containment vessel, characterized by comprising a heat insulating layer.