JP2003302488A - Leak seal structure for nuclear reactor well water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the structural soundness of a nuclear reactor pressure vessel during operation and ISI workability during replacement of a fuel and to prevent deterioration of a seal face immersed in the water, a stud bolt, its planting part, and the like. <P>SOLUTION: A basin seal skirt between a shell plate flange 2 of a nuclear reactor pressure vessel 1 and a nuclear reactor well 19 on the nuclear reactor storage vessel side is omitted for arranging a space, and in an immersed condition during fuel replacement, a sealing device 11 serving as a water penetration preventing mechanism is arranged for a flange seal face 21, a shell plate flange upper face 22, and a nuclear reactor well upper face 19d. In the stud bolt planting part, a seal ring 13 is arranged for screwing a waterproof plug 12, while in a residual stud bolt 6, a seal cap 14 is arranged. In this way, stress deformation of a basin seal skirt is dispensed with and the structure soundness is improved. In addition, work space is widened, and ISI (in-service inspection) workability is improved, while deterioration of the stud bolt and the planting part can be prevented. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a watertight seal structure for a reactor well covering a space between a reactor pressure vessel and a reactor containment vessel, and more particularly to reducing stress in a refueling seal skirt of the reactor pressure vessel. And a water-tight seal structure suitable for preventing corrosion and preventing damage from being caused by a water seal during a periodic inspection of a reactor pressure vessel.

[0002]

2. Description of the Related Art In a conventional connecting portion between a reactor pressure vessel and a reactor containment vessel, a basin seal skirt is welded to a seat provided on a body plate of the reactor pressure vessel. And, the tip of the basin seal skirt is connected to the bellows and further mates with the reactor well.

When the reactor pressure vessel is shut down, the stresses in the seat, the welding, and the basin seal skirt are generated by the mass of the basin seal skirt itself, but the stress is slight. However, when the reactor pressure vessel is put into operation, pressure acts on the inner surface of the reactor pressure vessel and the temperature further rises, so that the reactor pressure vessel is deformed in the radial direction and the axial direction, respectively. Will occur.

As a result of this deformation, stress is generated in the seat, weld and basin seal skirt. In particular, high stress is generated in the vicinity of the seat and the weld, which is not preferable from the viewpoint of ensuring the structural strength and soundness of the reactor pressure vessel.

In addition, when the body plate flange of the reactor pressure vessel is submerged in the fuel exchange in the periodic inspection of the nuclear power plant (hereinafter referred to as "regular inspection"), the end plate flange of the reactor pressure vessel is After removing the washer and opening it, water is sprinkled on the inner surface of the reactor pressure vessel and the reactor well. In this case, the flange sealing surface, the stud bolt, and the stud bolt embedded portion are exposed to the underwater environment.

Therefore, conventionally, the following problems and countermeasures have been taken. There is a problem that the stud bolts are rusted and deteriorated, and as a countermeasure, the stud bolts were covered with a screw catcher.

Since the stud bolt is pulled out due to the work at the time of refueling, there is a problem that the stud bolt implanting portion similarly suffers rust and deteriorates. As a countermeasure against this, the stud bolt implanting portion is closed. There was a waterproof plug.

Although the flange seal surface is made of a material having high corrosion resistance, it may be exposed to an underwater environment for a long time, and the flange seal surface may be damaged by a falling object during the work. A seal face protection device was provided to keep the seal face.

[0009]

In the conventional welded structure of the basin seal skirt of the above-mentioned conventional reactor pressure vessel, the radial pressure and axial deformation of the reactor pressure vessel, which are generated during operation, cause a high temperature near the welded portion. Since stress is generated, it is not preferable in terms of structural strength and soundness.

Further, at the time of refueling, since the flange sealing surface, the stud bolt, the stud bolt implanting portion, etc. are under the water environment, although measures against corrosion are taken into consideration, only individual measures are taken. In addition to the above, it is not preferable from the viewpoint of manufacturing and installation because it is composed of many parts.

In particular, the seal surface catching device is extremely complicated to handle because it is divided into several parts in the circumferential direction. Also, in order to fix the seal face protection device,
It is a work to open and close the stopper of the stud bolt and it is not workable.

Further, during the service period, it is necessary to perform an in-service inspection (ISI) of the welding line in the circumferential direction of the reactor pressure vessel on the above-mentioned welded portion, but the space of the portion is not the reactor pressure vessel. Since the space with the basin seal skirt is narrow, the workability of ISI is hindered, which is not preferable.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks and improve the structural integrity of a reactor pressure vessel during operation.
It is to improve the workability of ISI and ensure the soundness of the flange seal surface, the stud bolt, and the stud bolt implanting part in the underwater environment throughout the fuel exchange.

[0014]

In order to solve the above-mentioned problems, a reactor well seal structure according to the present invention is provided with a flange seal surface of a body plate flange of a reactor pressure vessel and a reactor well of a reactor containment vessel. During the regular inspection, the cover is used to cover the gap between the above and the structure, so that the cover is normally separated.

Further, when the basin seal skirt is provided, it has a structure that can be rotated by being separated from the overlay of the body plate flange, and at the time of water filling, a sheet having a waterproof seal structure on the upper surface of the body plate flange and the basin seal skirt. Provide a surface protection device. As a result, the stress deformation during operation of the reactor pressure vessel is not transmitted to the basin seal skirt, and the work space for ISI can be secured by shortening the basin seal skirt.

A stud bolt attached to the body plate flange is covered with a waterproof cap, and a waterproof plug is installed at the implanting portion from which the stud bolt has been removed. Use a seal structure.

[0017]

DETAILED DESCRIPTION OF THE INVENTION An example of an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a vertical cross-sectional view of a reactor pressure vessel according to the present invention, and FIG. 2 is an enlarged view of part A of FIG.

As shown in FIG. 1, the present invention has a structure in which a space is provided between the shell plate flange 2 of the reactor pressure vessel 1 and the reactor well 19 on the side of the containment vessel. It removes the conventional basin seal skirt in between.

FIG. 2 shows a sealing device 11 for mating with the reactor well 19 of the present invention. The sealing device 11 according to the present invention includes a flange sealing surface 21, a body plate flange upper surface 22.
And the reactor well upper surface 19d, and a mechanism for preventing water from entering the flange seal surface 21, the body plate flange upper surface 22 and the reactor well upper surface 19d in a state where the reactor pressure vessel 1 is submerged in water during fuel exchange. It is equipped with.

The detailed contents of this embodiment will be described below with reference to FIG.
It will be described with reference to FIG. 3 is an enlarged view of part B of FIG.
FIG. 4 is a view taken along line AA of FIG. 3 and shows a sealing structure when the stud bolt 6 is pulled out. Stud bolt 6
At the time of refueling during regular inspection, several passages are pulled out because a passage is secured for the workability of refueling (see FIG. 20).

[0021] In addition, several pieces are pulled out for the purpose of ISI.
In order to cope with such a situation, the sealing device 11 is provided with a receiving seat 11a, and the receiving seat 11a is provided with a seal ring groove 11b for installing the seal ring 13.

A waterproof plug 12 is placed on the receiving seat 11a.
The sealing plate 12a is installed. The waterproof plug 12 is formed with a torque wrench seat 12b for screwing in, and a screw portion 12c that engages with the stud bolt implanting screw portion 10.

By using the torque wrench seat 12b to screw in the waterproof plug 12, the seal ring 13 can be pressed and sealed. In this case, the sealing device 11 can also be pressed.

5 and 6 show a seal structure when the stud bolt 6 is embedded. FIG. 7 is a view taken along line AA of FIG. The stud bolt 6 is covered with a cylindrical waterproof seal cap 14.
As shown in FIG. 3, the flange 14a at the open end of No. 4 is
It is installed on the receiving seat 11a of the sealing device 11.

Further, a mounting bolt 14c is provided on the upper portion of the seal cap 14 for fitting with a screw hole provided on the upper portion of the stud bolt, and the handle 14b is rotated to press the seal cap 14 in the same manner as in FIG. Then, the seal ring 13 and the seal device 11 are pressed and sealed.
A seal 14e is also provided at the holding portion of the bolt 14c.

FIG. 8 and FIG. 9 show a sealing structure of the seal device 11 and the flange sealing surface 21 on the upper surface of the body plate flange 2 of the reactor pressure vessel. FIG. 9 shows AA of FIG.
It is a perspective view. Also in these figures, as in the above, the seal device 11 is provided with seal ring grooves 11c and 11d for installing the seal rings 15 and 16.

10 and 11, the reactor well 19 is shown.
The seal structure of the upper surface is shown. FIG. 11 is a view taken along line AA of FIG. A seal ring groove 19a for installing the seal ring 19b is provided on the upper surface of the reactor well.

The seal ring 1 shown in FIGS. 8 and 10.
5, 16 and 19b are compressed by the dead weight of the sealing device 11 and the water head pressure at the time of water filling for refueling, and the waterproof plug 12 shown in FIG. 3 and the seal cap 14 shown in FIG. Also, the sealing device 11 is compressed. Therefore, since the seal rings 15, 16 and 19b of the relevant portion are strongly compressed, the soundness of the seal mechanism can be improved.

As described above, by installing the above-mentioned sealing device 11, when the reactor pressure vessel 1 is submerged during refueling, the water 20 on the flange sealing surface 21, the upper surface of the shell plate flange 22 and the upper surface of the reactor well 19 is prevented. Intrusion can be prevented. Therefore, since the flange seal surface 21 and the body plate flange upper surface 22 are not affected by the corrosive environment, the soundness of these parts is ensured.

Further, the sealing device 11 includes a flange sealing surface 21, a shell plate flange upper surface 22 and a reactor well 19.
Since it can be installed over the entire range of the upper surface, it is possible to prevent damage to the relevant part due to falling objects in various operations during refueling.

Since a space can be secured between the reactor pressure vessel 1 and the reactor well 19 on the side of the reactor containment vessel, the welded portion 25 shown in FIG.
It is possible to improve the workability of ISI of the welding line in the circumferential direction. Further, since the water retention groove portion of the radioactive substance from the water of the basin seal skirt 7 shown in the reference example of FIG. 17 is eliminated, the radiation level of the regular inspection environment after draining is lowered.

The seal ring 13 shown in FIG.
The seal ring 14e shown in FIG. 5, the seal ring 13 shown in FIG. 6, the seal rings 15 and 16 shown in FIG.
The seal ring 19a shown in FIG. 0 can be sealed by providing a metal O ring or a material such as rubber.

Next, another embodiment of the present invention is shown in FIGS. In this embodiment, the basin seal skirt 8
Is completely separated from the body plate flange 2. FIG. 13 shows the structure of the basin seal skirt 8 which is fitted with the body plate flange 2.

As shown in these figures, the body plate flange 2
The seat 8a is provided on the upper part of the above, and the basin seal skirt 8 is installed on the seat 8a. As described above, by completely separating the basin seal skirt 8 from the body plate flange 2, the component can rotate, and particularly during operation, the rotation of the part is restricted due to the displacement difference. This is a structure that can reduce the stress that is generated. As a result, the strength and soundness of the basin seal skirt can be improved.

If, for example, the stress level generated in the basin seal skirt 8 is set to a level similar to that of the basin seal skirt 7 of the reference example of FIG. 17, the basin seal skirt 8 is moved vertically and horizontally. It is also possible to shorten the length of.

Further, FIG. 14 shows the details of the F portion of FIG. 12, which is a structure in which the upper surface 23 of the basin seal skirt and the sealing device 11 are fitted together, and the structure other than the J portion of FIG. It has the same structure as part B and part C in FIG.

Therefore, also in this embodiment, FIG.
The effect similar to that of the embodiment shown in FIG.
That is, when the reactor pressure vessel 1 is submerged during refueling, water 20 can be prevented from entering the flange sealing surface 21, the body plate flange upper surface 22 and the reactor well upper surface 19.
Since these seals are not affected by the corrosive environment, the integrity of the parts is ensured.

Further, since the sealing device 11 can be installed over the entire range of the flange sealing surface 21, the body plate flange upper surface 22 and the basin seal skirt upper surface 23,
It is possible to prevent damage to the relevant part due to falling objects in various operations during refueling.

Further, as described above, the basin seal skirt 8 can be made shorter in the vertical direction than the basin seal skirt 7 of the reference example (see FIG. 17) (the structure of the reference example is shown by a broken line). A space 26 can be secured between the reactor pressure vessel 1 and the basin seal skirt 8 on the reactor containment vessel side.

Therefore, it is possible to improve the workability of ISI of the welding line in the circumferential direction of the welded portion 25 of the reactor pressure vessel. Further, since the water retention groove portion of the radioactive substance from the water of the basin seal skirt 7 as in the reference example is eliminated, the radiation level of the regular inspection environment after draining water is lowered.

The seal ring 1 shown in FIG.
By providing a metal O-ring or a material such as rubber for each of 7 and 18, the relevant part can be sealed.

Here, reference examples of the present invention are shown in FIG. 17 and 18, the basin seal skirt 7 is attached by a seat 7a provided on the body plate 2 and welding 7b. The tip of the basin seal skirt 7 is connected to the bellows 9 and further engages with the reactor well 19.

In such a reference example, the following points are not considered. That is, when the reactor pressure vessel 1 is stopped, the state shown by the solid line in FIG.
b, and the stress of each part of the basin seal skirt 7,
It is generated by the mass of the basin seal skirt 7 itself, but its stress is small.

However, when the reactor pressure vessel 1 is put into operation, pressure acts on the inner surface of the reactor pressure vessel 1 and the temperature further rises. Therefore, as shown by the broken line in FIG. Radial direction R and axial direction L of furnace pressure vessel 1
Then, the deformations of ΔR and ΔL occur respectively.

As a result of this deformation, stress is generated in each of the seat 7a, the weld 7b, and the basin seal skirt 7. In particular, high stress is generated in the vicinity of the seat 7a and the weld 7b, which is not preferable from the viewpoint of ensuring structural strength and soundness.

When the fuel is changed during the regular inspection (periodic inspection) of the nuclear power plant, the body plate flange 2 is set to the position shown in FIG.
9 and FIG. 20, when submerged in water, as shown in FIG.
After removing the nut 5 and the washer 4 shown in FIG. 7 and opening the end plate flange 3, as shown in FIG. 19, water 20 is sprinkled on the inner surface of the reactor pressure vessel 1 and the reactor well 19.

In this case, the flange sealing surface 21, the stud bolt 6 and the stud bolt implanting portion 10 are exposed to the underwater environment. Therefore, as described as the problem to be solved by the present invention, there are problems such as deterioration of the stud bolt 6 and its implanted portion due to rust, and damage due to a fallen object during long-time work in an aquatic environment.

As measures against this, the measures shown in FIGS. 21 to 25 are taken. That is, as a countermeasure against the deterioration of the stud bolt 6, a screw catching tool 6a is provided as shown in FIG. 22, and as a countermeasure against the deterioration of the stud bolt implantation portion, a waterproof plug 31 is provided as shown in FIG. It is provided. In addition, as a measure against falling objects,
2 or as shown in FIG. 24, the seat surface catching device 30
Is provided.

However, these measures are not only independent measures, but also each is composed of a large number of parts. In particular, the seat surface catching device 30 for falling objects is divided into several parts in the circumferential direction, and in order to fix the seat surface protecting device 30, the stopper 30c is opened and closed as shown in FIG. It is necessary to attach the stud bolt 6 to the stud bolt 6.

Further, during the service period, it is necessary to perform an in-service inspection (ISI) of the weld line 25a in the circumferential direction of the container shown in FIG. 17 on the welded portion 25 of the reactor pressure vessel. The space 26 has a narrow working space between the reactor pressure vessel 1 and the basin seal skirt 7.

According to the embodiment of the present invention, the above problems can be solved. That is, since the basin seal skirt can be omitted or removed so as to be separable, the stress generated during the operation of the reactor can be reduced, and the soundness of the structural strength of the reactor pressure vessel can be improved.

Further, it is possible to avoid that the flange seal surface, the stud bolt and the stud bolt embedded portion are exposed to the underwater environment during the fuel exchange, and the flange seal surface, the stud bolt and the stud bolt embedded portion are sound. Can be secured. Also, I of the welding line of the reactor pressure vessel
The workability of SI can be improved.

[0053]

As described above, the present invention has the following effects. (1) Since the stress generated in the basin seal skirt can be reduced during the operation of the reactor pressure vessel, the structural strength and soundness can be improved.

(2) Even if the reactor pressure vessel is submerged during refueling, the flange seal surface, the upper surface of the body plate flange and the upper surface of the basin seal skirt are not affected by the corrosive environment. The soundness is secured, the handling during regular inspection is easy, and the workability can be improved. (3) It is possible to prevent damage due to falling objects in various operations during refueling.

(4) It is possible to improve the workability of ISI of the welding line at the welded portion of the reactor pressure vessel during the service period. (5) Since the basin seal skirt groove portion where radioactive substances in water are likely to be accumulated is eliminated, the radiation level in the regular inspection environment after draining water is reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a reactor pressure vessel showing an embodiment of the present invention.

FIG. 2 is an enlarged view of part A in FIG.

FIG. 3 is a detailed view of a B part in FIG.

FIG. 4 is an AA view of FIG.

FIG. 5 is a vertical sectional view showing a case where a stud bolt according to the present invention is present.

6 is a detailed view of a portion E in FIG.

FIG. 7 is a view taken along line AA of FIG.

FIG. 8 is a detailed view of a C portion of FIG.

9 is a view taken along line AA of FIG.

FIG. 10 is a detailed view of a portion D of FIG.

11 is a view taken along the line AA of FIG.

FIG. 12 is a vertical sectional view of a reactor pressure vessel showing another embodiment of the present invention.

FIG. 13 is an enlarged view of part F in FIG.

FIG. 14 is a detailed view of a portion F in FIG.

FIG. 15 is a detailed view of a J section in FIG.

16 is a view taken along line AA of FIG.

FIG. 17 is a vertical sectional view showing a reference example of the present invention.

FIG. 18 is a detailed view of a portion K of FIG.
The broken line shows the operating state.

FIG. 19 is a vertical cross-sectional view showing a water filling state of a reactor well at the time of refueling.

20 is a view taken along line AA of FIG.

FIG. 21 is an explanatory view showing a seal face keeping device in a reference example.

FIG. 22 is an explanatory diagram showing a seal surface catching device and a screw protector in a reference example.

23 is a view taken along the line AA of FIG.

FIG. 24 is a detailed sectional view of a portion L in FIG. 21.

FIG. 25 is a cross-sectional view of a waterproof plug according to a reference example.

[Explanation of symbols]

1 Reactor pressure vessel 2 Body plate flange 3 End plate flange 4 washers 5 nuts 6 stud bolt 7,8 Basin Seal Skirt 8a Body plate upper flange receiving seat 9 Bellows 10 Stud bolt implantation part 11 Sealing device 11c, 11d Seal ring groove 12 waterproof plug 13 Seal ring 14 Seal cap 14a flange 14b handle 14c Tightening bolt 14d screw hole 14e, 15, 16, 17, 18 Seal ring 19 reactor well 19a Seal ring groove 19b seal ring 20 water 21 Flange sealing surface 22 Upper face of body plate flange 23 Basin seal skirt top 25 Weld 26 space

Claims (4)

[Claims] 1. A structure having a structure in which an engagement portion between a shell plate flange of a reactor pressure vessel and a reactor containment vessel well is separated,
A watertight seal structure for a reactor well, in which a flat plate cover is installed on the upper surface of the shell plate flange and the reactor containment well when the reactor well is watered. 2. The shell plate flange of the reactor pressure vessel and the reactor containment vessel well have a structure in which the shell plate flange and the basin seal skirt are separated, and the shell plate flange and the basin seal are provided. A water-tight seal structure for a reactor well in which a flat plate cover is installed on the upper surface of the skirt with a sealing material interposed. 3. The watertight seal structure for a reactor well according to claim 1, further comprising a waterproof plug that protects an implanted portion of a stud bolt attached to the trunk plate flange in water. 4. The watertight seal structure for a reactor well according to claim 1, further comprising a waterproof cap for protecting the stud bolt attached to the body plate flange in water.