JPH1114779A - Construction of substructure in nuclear reactor containment vessel and module structure therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the construction process of a nuclear power plant by installing the substructure in a metallic liner to be constructed at the inner wall of an nuclear reactor containment vessel of a nuclear reactor building of the nuclear power plant at an early stage so as to be capable of early- starting construction of its upper part. SOLUTION: In the case of constructing a substructure in a metallic liner to be constructed at the inner wall of a nuclear reactor containment vessel by fitting part of a tunnel 9 for personnel access, which is disposed at the outer periphery of foundation, to a member constituting the foundation of a nuclear reactor pressure vessel by using this method, the part of the tunnel 9 is fitted to the part of the foundation so as to form an integral module structure 19. The integral module structure 19 is then installed by suspending it in the metallic liner 3 which is constructed at the inner wall of the nuclear reactor containment vessel which is the constructing position of the substructure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention belongs to the technical field of the construction of a containment vessel.

[0002]

2. Description of the Related Art An improved boiling water reactor (hereinafter referred to as ABWR)
Called. ) In the construction of a plant, a cylindrical R on which a reactor pressure vessel (hereinafter referred to as RPV) is installed.
The foundation of PV (hereinafter referred to as pedestal) is made of a cylindrical steel plate that also serves as a concrete-casting formwork to support the load of RPV and withstand vibration sufficiently. In the space between the cylindrical steel plates of
It has a structure filled with high-strength concrete, and is divided into several blocks of about 5 steps
Each is carried into the PV and set.

[0003] Further, equipment, piping, support structures, and the like provided in the inner space of the steel plate of the inner cylinder of the pedestal have been carried in and set individually for each RPV after the pedestal construction is completed and before the RPV is suspended.

[0004] In addition, regarding a tunnel for personnel access (hereinafter, referred to as a tunnel), the building side and the pedestal side rise above the height at which the tunnel is set, and when the tunnel can be brought into the set position, the tunnel is located above the tunnel. By the time the setting of the diaphragm floor to be installed in the factory starts, it is carried in and set by the hoist.

[0005] Until the tunnel is completely set, the tunnel is supported by a temporary mount or the like.

After setting the tunnel, the inside of the tunnel is painted, and then the site area is handed over to a worker who installs electricity and equipment, and the piping, support members, ceiling structural members, and the like are installed.

[0007] Most of the pipes (small diameter) in the tunnel are densely laid on the ceiling of the tunnel, and the amount of material is large.

For the construction of the pipe, it is necessary to assemble the scaffold after the area is handed over from the building side, and there is a limit to inputting a large number of personnel due to the special situation in the tunnel (the work space is narrow).

For this reason, a considerable amount of time is required for piping work, which is critical in the construction process of the containment vessel.

[0010] Further, since the tunnel is the only product and personnel access route leading to the lower part of the dry well (hereinafter referred to as D / W) in the containment vessel, product and personnel access to the D / W is frequent. The construction in the access tunnel had to be carried out in a timely manner.

[0011]

SUMMARY OF THE INVENTION As a recent trend in nuclear power plant construction, shortening of the construction period is required.

In order to shorten the construction period, it is necessary to shorten the building process on the building construction side, which is a critical path, and the RPV and furnace interior work on the equipment installation side, which are sub-critical.

The work undertaken by the former tends to be shortened with the progress of technology.

Accordingly, the subcritical RP
There is a need to shorten the V and furnace work concurrently.

At present, personnel are put in and day and night work systems are used to cope with the shortening process. However, this measure has a limit.

As an improved countermeasure, there is a method in which the reactor internal structure is brought to the site with the RPV installed in the factory in advance, and is carried in. However, in this case, even in the present situation, a crane for lifting the RPV is used. Considering that the capacity is full, it is necessary to increase the capacity of the RPV lifting hoist.

On the other hand, in order to shorten the process without changing the assembly range of the furnace internal structure, it is necessary to carry in the RPV for carrying out the furnace internal work ahead of time.

In order to implement this, it is necessary to accelerate the construction of the RPV pedestal and its surroundings, and to cope with the early loading of the RPV.

On the other hand, there is a demand for hassle-free construction of piping for RPV.

The RPV is required to cope with an infinite number of pipes in a building. In particular, the lower D / W portion operates and controls a control rod drive mechanism (hereinafter referred to as CRD) provided in the lower D / W portion. Many small diameter pipes are associated with RPV.

That is, the CRD piping work in the RPV pedestal and in the access tunnel has become subcritical in the process.

In addition, many small-diameter pipes are densely arranged on the ceiling of these pipes, and a large amount of labor and steps are required to complete the work.

On the other hand, in the working environment, concrete is poured into the surrounding area at the time of construction, so that the environment becomes high temperature and high humidity, which is not a good environment.

One of the solutions in such a situation is to make an access tunnel module (with piping, support members, gantry, etc.).
Since the RPV pedestal and access tunnel are carried separately, there are many pipe joints and the piping module must be a loose module.

Therefore, the number of man-hours required for setting work on site increases,
The advantages of modularization are reduced.

In order to increase the merits of modularization under such conditions, it is important to reduce the on-site work for the products (piping, support members, permanent mounts, etc.) constituting the module. We need a tighter module.

Accordingly, it is an object of the present invention to shorten the construction period of a nuclear power plant including a reactor containment vessel by constructing a lower structure of the containment vessel early.

[0028]

A first means for achieving the object of the present invention is to provide a part of a foundation for a reactor pressure vessel, a part of a tunnel for personnel access provided around the outside of the foundation. A method for constructing a substructure in a reactor containment vessel by attaching a part of the tunnel to the foundation part to form an integral module, and then moving the module to a construction position of the substructure A method of constructing a substructure inside a reactor containment vessel, characterized in that it is suspended and installed, and a part of a foundation of a reactor pressure vessel and a part of an access tunnel for personnel are simultaneously suspended and installed at an installation position. Action is obtained,
By this operation, the installation of the upper part of the containment vessel, such as the installation of the reactor pressure vessel, can be performed earlier and the construction process of the nuclear power plant can be shortened.

[0029] The second means may also be the first means, wherein, before the suspension, the module is provided with the reactor pressure vessel or the internal space in the interior space surrounded by the base portion and the tunnel portion before the suspension. A method for constructing a lower structure in a reactor containment vessel, characterized in that it is equipped with a pipe connected to equipment installed in the reactor, and a structural body installed in the interior space and the tunnel portion, and placed. Yes, in addition to the function and effect of the first means, it is possible to obtain the effect that the piping, equipment and structural body in the internal space and the tunnel are simultaneously carried into the installation location by hanging the module and installed, so that piping work and equipment can be obtained. Installation work and structural frame work can be largely omitted, avoiding the time zone when the tunnel is used as an access route to the internal space, and the work environment is poor The hassle of performing the plumbing in the tunnel can also be eliminated, the construction process of a nuclear power plant can be obtained an effect that can be further shortened.

[0030] Similarly, the third means is the first means or the second means, wherein the suspending is performed by suspending the respective parts with a rope vertically suspended from a suspending balance, and suspending the suspending balance by a hoist. A method for constructing a lower structure in a reactor containment vessel, characterized in that, in addition to the function and effect of the first means or the second means, the base of the reactor pressure vessel and the tunnel are ropes vertically suspended from a suspension balance. Because it is suspended vertically, the rope and the reactor pressure vessel foundation and tunnel are less likely to be forced than when the rope is hung diagonally, and a tunnel is attached to the reactor pressure vessel foundation. When the large and heavy module is hung, the module can be easily hung and installed at the installation position without causing deformation of the module.

[0031] Similarly, the fourth means is the temporary mounting device according to the first means, the second means or the third means, wherein a portion of the tunnel of the module suspended in the containment vessel is previously set in the containment vessel. A method for constructing a lower structure in a reactor containment vessel, characterized in that the module is installed in the reactor containment vessel in addition to the function and effect of the first means, the second means or the third means. The module suspended in the vessel receives the part of the tunnel protruding from the base of the reactor pressure vessel on a temporary mount, and removes the suspension means from the tunnel from the tunnel. The effect of being able to be attached is obtained, and the effect that accurate installation work can be quickly performed is obtained.

A fifth means is the same as any one of the first means to the fourth means, wherein a tunnel portion is divided into a part incorporated in a module and the other part, and the module is installed. Before installing a metal liner on the inner wall of the reactor containment vessel, after that, attach the other part of the tunnel to the metal liner, and then carry the module to the installation position and remove part of the tunnel A method for constructing a lower structure in a reactor containment vessel, characterized in that the lower structure is connected to the other part of the tunnel so as to form a series. As the module is lowered along the metal liner towards the installation position, some of the tunnels built into the module have a reduced tunnel length Action tunnel incorporated in joules is suppressed to cause an accident in contact with a metal liner is obtained, the construction process of the secure in the nuclear power plant is an effect that can be shortened to obtain.

The sixth means also includes a lower part inside the reactor containment vessel which is formed as an integral module by attaching a part of a tunnel for personnel access disposed around the outer periphery of the foundation to a part constituting a foundation of the reactor pressure vessel. It is a module structure used for the construction method of the structure, and since the module structure is configured by integrating the base part and the tunnel part of the reactor pressure vessel into the module members, the module structure is When used for construction, if the module structure is suspended at the installation position during construction, the foundation of the reactor pressure vessel and the access tunnel for personnel are simultaneously suspended at the installation position and installed. As a result, there is an effect that the installation of the reactor pressure vessel can be performed earlier and the construction process of the nuclear power plant can be shortened.

A seventh means is also the sixth means, wherein the piping connected to the reactor pressure vessel or the equipment installed in the internal space is provided between the internal space surrounded by the base portion and the tunnel portion. And a module structure for use in a method for constructing a lower structure in a reactor containment vessel equipped with the internal space and a structural skeleton installed in a portion of the tunnel, and an operation effect of the sixth means. In addition to,
When the module structure is used for construction, the piping, equipment, and structural body in the internal space and tunnel can be simultaneously carried to the installation location by hanging the module and installed, so that piping work and equipment installation work can be performed. Installation work can be largely omitted, avoiding the time zone when the tunnel is used as an access route to the internal space, and eliminating the troublesome work of performing plumbing work in a tunnel with a poor working environment, The effect that the construction process of a plant can be further shortened is obtained.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of a nuclear power plant, a reactor building 1 shown in FIG. 1 is employed in a nuclear power plant.

A reactor containment vessel 25 for housing the reactor pressure vessel 2 is constructed in the reactor building 1, and a metal liner 3 is installed and installed on the inner wall of the reactor containment vessel 25. I have.

Inside the metal liner 3 installed on the inner wall of the reactor containment vessel 25, a cylindrical pedestal 4 as a base for mounting the reactor pressure vessel 2 is installed.

The space surrounded by the pedestal 4 and the reactor pressure vessel 2 is a space called a lower dry well 5.

In the lower drywell 5, a control rod drive mechanism 6 for operating control rods for controlling the core in the reactor pressure vessel 2 and a number of other devices are provided. .

A pipe 8 for passing a pressure fluid or an electric wire is connected to these devices.

In order to support these devices and pipes 8, a structural frame 7 made of steel is constructed in the space inside the lower dry well 5.

The pipes 8 are passed from the lower dry well 5 to a tunnel 9 for personnel access to the reactor building 1 outside the reactor containment vessel 25.

The tunnel 9 is used as an access route (passage) between the inside of the reactor building 1 and the lower dry well 5.

A diaphragm floor 10 is provided above the tunnel 9.

In such a reactor building 1, unless the tunnel 9 and the pedestal 4, which are the lower structures in the reactor containment vessel 25, are constructed, the upper structure such as the diaphragm floor 10, etc., which is higher than the tunnel 9 and the pedestal 4. It cannot be constructed, and the installation of the reactor pressure vessel 2 on the pedestal 4 will be delayed.

The following construction method is adopted in order to eliminate the factor of delay in the construction of such a plant.

Although the pedestal 4 is divided into five stages in total, in this embodiment, the first stage and the second stage from the bottom are grounded as shown in FIG. 3 in consideration of the load capacity that can be handled by the crane. They are superposed in the assembly yard 13 and integrated by welding or the like.

The pedestal 4 has a double-cylindrical configuration comprising an inner cylinder 11 made of a steel plate and an outer cylinder 12 made of a steel plate. The inner cylinder 11 and the outer cylinder 12 are connected by a partition made of a steel plate. It is manufactured integrally.

If the crane has the ability to handle all the steps of the pedestal 4 at once, it is ideal to integrate all the steps of the pedestal 4 in the ground yard 13 for shortening the process.

A vent passage 14 is provided between the outer cylinder 12 and the inner cylinder 11 of the pedestal 4 to allow the fluid in the drywell space above the diaphragm floor 10 to pass through the pressure suppression chamber space below the diaphragm floor 10. Have been.

The lower end of the vent channel 14 is constituted by a horizontally installed pipe 15, and the discharge port of the fluid is directed horizontally so as to discharge the fluid horizontally.

As shown in FIG. 3, such a portion of the pedestal 4 is erected vertically in an outdoor yard 13 near the position where the reactor building 1 is to be constructed. Is placed.

As shown in the upper right part of FIG. 3, a portion of the tunnel 9 made in another place is carried by a crane to the upper part of the temporary gantry 16.

The portion of the tunnel 9 on the side to be attached to the metal liner 3 is partially divided, and the divided tunnel 26 is divided at a position where the tunnel is to be attached in advance as shown in FIG. Attached to.

The transported tunnel 9 is placed on a temporary gantry 16 and fixed to the pedestal 4 by welding or the like, like the tunnel 9 on the left side of FIG.

The tunnel 9 carried on the temporary gantry 16
As shown in FIG. 2, a plurality of pipes 8 are previously installed on the inner ceiling via supports 17 of the pipes 8 as shown in FIG.
Is built in.

In addition, below the inside of the tunnel 9, a permanent mount 18 is installed as a scaffold for both walking and working.

As described above, the timing for installing the permanent mount 18 and the pipe 8 in the tunnel 9 may be set before the tunnel 9 is brought into the ground yard 13.
The tunnel 9 may be installed after being attached to the pedestal 4.

If the pipes 8 and the like are installed and placed in the tunnel 9 before the tunnel 9 is brought into the ground yard 13, the work in the ground yard 13 is simplified, and The assembling work in the unit 13 can be performed quickly.

Further, as for the pedestal 4, a structural frame 7 made of a steel frame is fixedly installed on the pedestal 4 as shown in FIG. 3 in the space surrounded by the pedestal 4, and supports the pipe 8 from the structural frame 7. Piping 8 supported through
Is installed.

The piping 8 and the structural body 7 in the pedestal 4
May be installed before or after the tunnel 9 and the pedestal 4 are fixed.

The pipes 8 installed in the tunnel 9 and the pipes 8 installed in the space surrounded by the pedestal 4 are connected to each other in large numbers. You may leave it.

In this case, after connecting and fixing the tunnel 9 to the pedestal 4, the pipe 8 is connected to the pedestal 4.
And the tunnel 9 at a stretch, the pedestal 4
In comparison with the case where the pipes 8 are individually installed in the tunnel 9 and the two pipes 8 are finally connected, the work of adjusting the connection position and the angle of the pipes 8 is not required, so that the work becomes easier, 8 can also be installed with the main contents for most of the entire length.

When the assembly at the ground yard 13 is completed, a module structure 19 in which the pedestal 4 and the tunnel 9 are integrally assembled is completed.

In the module structure 19, a plurality of suspension fittings on which the wire ropes 20 are hooked are dispersed and fixed to the pedestal 4 portion and the tunnel 9 portion.

The construction of the reactor building 1 is proceeded while such a module structure 19 is being produced, and as shown in FIG.
1 is installed on the metal liner 3 installed on the inner wall of the reactor containment vessel 25 and the reactor building 1, and the metal liner 3 installed on the inner wall of the reactor containment vessel 25 can also accommodate the module structure 19. It has been built as much as possible.

When constructing the metal liner 3,
A split tunnel 26 may be attached to the metal liner 3 in advance, and the metal liner 3 with the split tunnel 26 attached may be suspended by a crane and brought into the work position of the metal liner 3. The split tunnel 26 may be mounted on the metal liner 3 after being suspended by a crane, carried into the construction position of the metal liner 3, and after installation of the metal liner has been completed.

Thereafter, the module structure 19 in the ground yard 13 is lifted by the outdoor crane 22 and suspended in the metal liner 3.

FIG. 4 shows the hanging operation.

At the time of suspension, the module structure 19
Is large and the tunnel 9 projects horizontally and easily collapses or deforms. To prevent this, the following suspension method is adopted.

That is, as shown in FIG. 4, a hanging balance 23 is hung from a crane 22, and a wire rope 20 is hung vertically from the hanging balance 23 to a hanging fitting attached to the pedestal 4 portion and the tunnel 9 portion. Hang over.

The hanging balance 23 has a cross-shaped plane shape so that the wire rope 20 is vertical.

In this manner, the module structure 19 is lifted by the crane 22. In the suspended state, since the wire rope 20 is vertical, the wire rope 20 is inclined and a horizontal component is applied to the module structure 19. No module phenomenon 1
The module structure 19 can be prevented from being collapsed or deformed without applying excessive force to the module structure 9.

The module structure 19 lifted by the crane 22 is moved by the crane 22 to the metal liner 3 installed on the inner wall of the containment vessel 25 as shown in FIG.
It is carried right above.

Before the carrying work, the reactor containment vessel 2
A temporary gantry 16 for receiving the tunnel 9 so as not to bend is provided at the bottom of the gantry 5.

The module structure 19 carried right above the metal liner 3 installed on the inner wall of the containment vessel 25
Is suspended by the crane 22 and the reactor containment vessel 25
A portion of the pedestal 4 is installed on the bottom of the pedestal 4 and a portion of the tunnel 9 is supported by the temporary gantry 16 and connected in series to a split tunnel 26 attached to the metal liner 3 by welding as shown in FIG. You.

The tunnel 9 thus connected can enter and exit from the hatch 21.

The reason for using the split tunnel 26 is that when the tunnel is handled without being split, the module structure 19 is suspended between the inner wall surface of the metal liner 3 and the tip end of the tunnel 9 when the module structure 19 is suspended in the metal liner 3. In order to avoid this, an interference accident may occur.

The temporary gantry 16 supporting the tunnel 9 during the installation of the tunnel 9 of the module structure 19 is removed to the outside of the reactor building 1 after the installation of the tunnel 9 is completed. .

The module structure 19 is a metal liner 3
When installed inside, the pipe 8, the structural body 7, and the equipment are brought into the space surrounded by the pedestal 4 and the tunnel 9 at the same time. Therefore, it is possible to drastically reduce the carrying-in work and the construction work related to the articles such as the above, and to promote the construction work above the module structure 19.

Further, the bottom of the reactor containment vessel 25 is located at a deep portion of the reactor building 1 and a large amount of moisture comes out from the surrounding concrete and the like during construction, and the moisture is large, but the humid and narrow space is present. The amount of work in the work environment can be reduced.

After the module structure 19 has been installed, the tunnel 9 can be used as an access route for personnel and equipment in the space surrounded by the pedestal 4 at an early stage. Work can be promoted.

After the installation of the module structure 19,
The situation where the upper stage number from the third stage of the pedestal 4 is assembled and the space between the inner cylinder 11 and the outer cylinder 12 of the pedestal 4 is filled with concrete so that the reactor pressure vessel 2 can be quickly installed on the pedestal 4 Become.

The construction of the reactor building 1 around the metal liner 3 is also proceeding.

According to this embodiment, the following effects can be obtained.

According to the present embodiment, since the pipe 8 on the ceiling portion inside the tunnel 9 is set in advance and carried into the tunnel 9,
The work of installing the piping 8 in the building is labor-saving,
Since the pipe 8 can be set in the tunnel 9 in a place where the working environment is prepared, the installation accuracy can be improved.

As a result, the construction period of the piping 8 after setting the access tunnel 9 is greatly reduced, and the construction period of the plant construction process of the nuclear power plant can be shortened.

Further, since the amount of work in the reactor building 1 is reduced, the work efficiency is increased, and the effect of shortening the construction period is similarly obtained.

Since the portion of the pedestal 4 and the portion of the tunnel 9 are integrated and carried in, access to personnel and equipment, that is, construction work in the lower drywell 5 can be started immediately after carrying in. The effect of shortening the construction period can be obtained.

[0090]

According to the first aspect of the present invention, the base portion of the reactor pressure vessel and the portion of the personnel access tunnel are simultaneously suspended at the installation position and installed.
The effect that the construction process of a nuclear power plant can be shortened is obtained.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, construction in the space surrounded by the base part of the reactor pressure vessel and in the part of the tunnel is simplified. The effect that the construction process of a nuclear power plant can be further shortened is obtained.

According to the third aspect of the present invention, in addition to the effects of the first or second aspect of the present invention, there is an effect that the module can be hung at the installation position of the module so as not to apply excessive force to the module. can get.

According to the fourth aspect of the present invention, in addition to the effects of the first, second or third aspect of the present invention, a temporary tunnel portion which is easily deformed by projecting from the base portion of the reactor pressure vessel is provided. The effect is obtained that the gantry supports and can quickly perform the accurate installation work of the tunnel portion.

According to the fifth aspect of the present invention, in addition to the effects of any one of the first to fourth aspects of the present invention,
The effect of suppressing the accident of contact between the module and the metallic liner of the containment vessel and shortening the construction period of the nuclear power plant safely and reliably is obtained.

According to the sixth aspect of the present invention, since the base portion of the reactor pressure vessel and the portion of the access tunnel for personnel are formed as an integrated module structure, the module structure can be used for construction. Thus, the base part of the reactor pressure vessel and the part of the access tunnel for personnel can be simultaneously carried into the installation position and installed, so that the effect of contributing to shortening the construction process of the nuclear power plant can be obtained.

According to the invention of claim 7, in addition to the effect of the invention of claim 6, in addition to the effect of the invention of claim 6, the base of the reactor pressure vessel at the installation position of the base of the reactor pressure vessel and the access tunnel for personnel is installed. The construction in the space enclosed by the part and the part in the personnel access tunnel is reduced, and the effect that the construction period of the nuclear power plant can be further reduced can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a reactor building in a nuclear power plant.

FIG. 2 is an elevational view showing a module structure of an access tunnel used in an embodiment of the present invention in a partial sectional view.

FIG. 3 is an elevational view in partial cross-section showing a situation where a module structure according to an embodiment of the present invention is being manufactured in a ground yard.

FIG. 4 is an elevational view with a partial cross section showing a state where the module structure according to the embodiment of the present invention is suspended at an installation position.

FIG. 5 is an elevational view in partial cross-section showing a situation where the module structure according to the embodiment of the present invention is installed at an installation position.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor building, 2 ... Reactor pressure vessel, 3 ... Metal liner, 4 ... Pedestal, 5 ... Lower dry well, 6 ... Control rod drive mechanism, 7 ... Structural body, 8 ... Piping, 9 ... Tunnel, 10 ... diaphragm floor, 11 ... inner cylinder, 12 ... outer cylinder, 13 ... ground yard, 14 ... vent passage, 15 ... pipe,
16: temporary mount, 17: support, 18: permanent mount, 1
9 ... Module structure, 20 ... Wire rope, 21 ...
Hatch, 22: Crane, 23: Hanging balance, 25: Reactor containment vessel, 26: Split tunnel.

Continued on the front page (72) Inventor Koichi Gota 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Inside Hitachi, Ltd. Hitachi Plant (72) Inventor Koichi Murayama 3-1-1, Sachimachi, Hitachi-shi, Ibaraki No.Hitachi Ltd.Hitachi Plant

Claims (7)

[Claims] A method for constructing a substructure in a containment vessel by attaching a part of a tunnel for personnel access provided around the foundation to a member constituting a foundation of a reactor pressure vessel, The lower part in the reactor containment vessel, characterized in that the part of the tunnel is attached to the part of the foundation to form an integral module, and then the module is suspended and installed at the construction position of the lower structure. Construction method. 2. The reactor according to claim 1, wherein the module is installed in the reactor pressure vessel or the internal space in the interior space surrounded by the foundation portion and the tunnel portion before the suspension. A method for constructing a lower structure in a reactor containment vessel, wherein a pipe connected to equipment and a structural body installed in a portion of the internal space and the tunnel are equipped and placed. 3. The atom according to claim 1, wherein said suspending is performed by suspending each of said portions with a rope vertically suspended from a suspending balance, and suspending said suspending balance by a lifting machine. Construction method of the lower structure inside the reactor containment vessel. 4. A reactor according to claim 1, 2 or 3, wherein a portion of the tunnel of the module suspended in the containment vessel is received by a temporary mount previously set in the containment vessel. A method for constructing a lower structure in a containment vessel, wherein the module is installed. 5. The tunnel according to claim 1, wherein the tunnel portion is divided into a part incorporated in the module and the other part, and before the module is installed. Constructing a metal liner on the inner wall of the reactor containment vessel, after which the other part of the tunnel is attached to the metal liner, then the module is brought into the installation position and part of the tunnel is A method for constructing a lower structure in a containment vessel, wherein the lower structure is connected to another part in a series. 6. Construction of a lower part structure inside a reactor containment vessel as an integral module by attaching a part of a tunnel for personnel access provided around the foundation to a part constituting a foundation of the reactor pressure vessel. Modular structure used in the method. 7. A pipe according to claim 6, wherein said internal space surrounded by said base portion and said tunnel portion communicate with said reactor pressure vessel or equipment installed in said internal space. A modular structure for use in a method for constructing a lower structure in a reactor containment vessel equipped with a space and a structural frame installed in a portion of the tunnel.