JPS6147587A - Reactor vessel housing leak repair device - 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] [Field of Application of the Invention] The present invention relates to a nuclear reactor pressure vessel C hereinafter referred to as PY. ] The stub tube and control rod drive mechanism housing (
Hereinafter, it will be referred to as C-D housing. ) This article relates to a repair device adopted as a measure to prevent reactor water from leaking from the welded parts and the vicinity thereof.

[Background of the invention]

The CRD housing and stub tube inside the RPV have a groove structure as shown in FIG. That is, a through hole is provided in the PVI, which has been overlaid with an overlay weld 10 made of Inconel material, etc., and one end of the cylindrical stub tube 2 that communicates with the hole IA is connected to the welded portion 3 on the inner surface of the PVI. It is attached through. RPVI to this stub tube 2
A C-box D housing 4, which passes through the wall and passes through the stub tube 2, is attached via a weld 5.

Domestic conventional boiling water type atomic a CRD housing 4 is 5
US304 series steel pipes are being used for the new year, and high residual stress occurs in the heat-affected zone near the welded part 5 of the CRD housing 4, and a ROM-depleted layer is generated along the grain boundaries, resulting in stress corrosion cracking. Sensitivity to occurs. Further, some foreign plants use 5US304 steel pipes for the stub tube 2, and in these plants, susceptibility to stress corrosion cracking occurs in the vicinity of the welded portion 5 of the stub tube 2. Therefore, the C of 5US304 series steel pipe
In the unlikely event that stress corrosion cracking occurs in the HD housing 4 and stub tube 2 and reactor water in the RPV1 leaks, it is necessary to develop a device to prevent leaks.

Furthermore, the stub tube 2 of domestic boiling water FFL reactors is made of Inconel 600 series material, which is an SCC-resistant material.

In the event that stress corrosion cracking occurs in the CB and D housings 4 and the stub tubes 2 and reactor water leaks, the leak prevention method is to use the existing CI' (,D The housing 4 and stub tube 2 are made of new 1Ilitscc material.
There is a permanent repair method to replace the RD housing and stub tube. CR after being replaced in this way,
Figure 12 shows the structure of the D housing and stub tube. According to this method, the C housing and stub tube can be replaced with new SCC-resistant materials, so the C housing and stub tube can be replaced with new SCC-resistant materials.
RD housing can be said to be highly reliable.
The method of repairing the structure shown in Fig. 1 to the structure shown in Fig. 12 is as follows.
Cut the existing CR, D housing 4 and stub tube 2, and install a new stub tube 6 on the inner surface of the PV lower mirror IC.
It is supposed to be attached via the welding part 7. In this case, the welding and cutting @ line of the existing stub tube is it P
This is considered to be undesirable since it is a three-dimensional complex shape that follows the inner surface of the V-lower mirror IC, requires a long time to weld and cut, and there is a risk of radiation exposure for workers involved in repair work. Also, main repair work? If this is the case, it will be necessary to develop special equipment such as automatic welding machines and cutting machines, which will take a long time to develop. A sealing device (commonly known as the caisson method) for use in the permanent repair method of replacing C-hole housings and stub tubes is known from Japanese Patent No. 56-89992.

FIG. 13 shows the structure of this water seal device made by Koyo.

As shown in FIG. 13, the known water seal device 29 has a cf
When repairing the LD housing and stub tube, it is a device that allows repairs to be carried out with reactor water present from the perspective of reducing radiation exposure for workers.
(This is effective in isolating the D housing and stub tube from the reactor water. However, the reactor cannot be operated with the water sealing device 29 shown in Fig. 13 installed and sealed. It is not possible to prevent leakage of reactor water from the CAD housing and stub tube during reactor operation.

From the standpoint of radiation exposure for workers involved in repair work on Ij, CRD housings, and stub tubes, the repair work must be completed in a short period of time, and if it is necessary to take immediate countermeasures, we will It is necessary to develop a repair device for C-D housings and stub tubes. or,
It is also necessary to prevent leakage D and to restart operation sooner.

[Purpose of the invention]

An object of the present invention is to easily prevent leakage near the weld between a housing and a stub tube in a nuclear reactor pressure vessel while restarting operation as quickly as possible.

[Summary of the invention]

The present invention provides an apparatus comprising a stub tube with one end fixed to the reactor pressure vessel, and a housing that is passed through the stub tube and welded to the other end of the stub tube, which is supported from the reactor pressure vessel. a first member disposed along the outer periphery of the stub tube; a second member disposed above the other end of the stub tube along the outer periphery of the housing; and an upwardly tapered portion of the first member and the second member. a third member installed through the surface;
The third member is provided between the member and the housing for fixing the third member to the housing, and each seal ring is provided on the inner peripheral side of the first member and the second member. This is a repair device for preventing leaks in the nozzle of a nuclear reactor vessel, and uses a tapered surface to press each seal ring against the housing and the stub tube to repair the vicinity of the weld between the housing and the stub tube. 1. Second. It is possible to create a state in which there is no flow of reactor water between the outside and outside of the area surrounded by the third member.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 10.

Figure 10 shows the RPV of a boiling water reactor.
1 is L% PV fuselage IB, RPV lower mirror 1 (JP!Birin PV
It consists of an upper M (not shown).

It is fixedly installed on the pedestal (not shown) of the reactor containment vessel by the RP V l & Yoskirt 8. Also,
The stub tube 2 is fixed to the RPv lower mirror IC by a welded portion 3. On the other hand, the CRD housing 4 is fixed to the stub tube 2 via a welded portion 5.

FIG. 11 is a sectional view showing a state in which the C-cutting housing 4 is fixed to the stub tube 2 via the welding part 5, and the stub tube 2 is fixed to the aPV lower mirror IC via the welding part 3. Inconel overlay ID is applied to the inner surface of the Pv lower mirror IC. 5A is a sensitized area formed in the CRI housing 4 by welding 5.

FIG. 1 is a sectional view of a mechanical seal device for repairing a C-hole housing according to an embodiment of the present invention.

The mechanical seal device consists of a plurality of cylindrical structures 10, 11°12.13 each having a tapered upper or lower surface.
, 14, a plurality of seal rings 20, 21, 22 degrees 23, 24, 25 incorporated in the cylindrical structure, a plurality of cylindrical structures 16, 17 for pushing the seal rings,
18.19 A seal part main body constituted by 19, a circle-shaped structure 9 for supporting the seal part main body from the PVIO lower mirror IC, and a cylinder for fixing the seal part main body. The shaped structure 15 forms a seal at two places, the outer surface of the stub tube 2 and the outer surface of the C-type D housing 4, and seals are formed at two places, the outer surface of the stub tube 2 and the outer surface of the C-type D housing 4. If this occurs, these seals will prevent leakage of reactor water. The first cylindrical structure '4J9 has a spherical shape whose lower surface is in contact with the inner surface of the lower mirror IC of the reactor pressure vessel, and whose upper surface is the second cylindrical structure 1.
It has a structure that supports the main body of the mechanical seal device by making plane contact with the main body of the mechanical seal device. The second cylindrical structure 10 supported by the first cylindrical structure 9, the third cylindrical structure 11, the fourth cylindrical structure 12, the eighth cylindrical structure 16, the first
Seal ring 20X 3rd seal ring 221 minutes and 4th
The nonyl ring 23 forms the lower seal of the mechanical 7-rule device.

The second cylindrical tj4 structure 10 has a flat bottom surface and a tapered top surface.2. Its lower surface contacts the first cylindrical structure 9 . A first seal ring 20 is fixed to the inner peripheral surface of the second cylindrical structure 10 .

The second cylindrical structure 10 and the first seal ring 20 are provided with notches as shown in Fig. 242 The inner diameter of the cylindrical structure 10 and first seal ring 20 is The diameter should be large enough to allow the tube to pass through the buckle part of the stub tube 2.

Further, the second cylindrical structure 1o is formed by moving the third cylindrical structure 11 and the fourth cylindrical structure 12 in the direction of the reactor pressure vessel lower mirror 1c through their respective tapered surfaces. The notched part is shown in Figure 5.

It contracts to the state shown in FIG. 6, and the seal ring 2° can also contract in the same way. By this contraction, the first seal ring 20 is pressed against the outer surface of the stub tube 2 to form a seal. Further, the third seal ring 2 is inserted into the groove provided on the upper surface of the first cylindrical structure 10 via the eighth cylindrical structure 16.
By crimping 2, the intrusion of reactor water through the tapered surfaces that are the contact surfaces of the second cylindrical structure 1o and the fourth cylindrical structure 12 is prevented, and a seal portion is formed. In this way, the first seal ring 20. The third seal ring 22 forms the lower seal portion of the mechanical 7-rule device. Further, to prevent reactor water from entering through the gap between the third cylindrical structure 11 and the fourth cylindrical structure 12, a fourth seal ring 23 is installed on the eighth cylindrical structure 16 inserted into the gap. By pressing the fourth seal ring 23 through the ninth cylindrical structure 17, a seal is formed and prevented.

The third seal ring 22 and the fourth seal ring 2
3 is performed by tightening the threaded portion 17a cut on the outer surface of the ninth cylindrical structure 41.f relic 17 to the threaded portion 12a cut on the upper inner surface of the fourth cylindrical structure 12. For this purpose, a thread is cut on the outer surface of the ninth cylindrical structure 17 so as to engage with a thread cut on the inner surface of the fourth cylindrical structure 12. 3rd cylindrical structure 11, 5th cylindrical structure 13, 6th cylindrical structure 14, 10th cylindrical structure 18, 11th cylindrical structure 19, 27th ring 21, 5th seal ring 24 and the sixth seal link 25 form an upper seal portion of the mechanical seal device. The outer circumferential side of the lower surface of the sixth cylindrical structure 14 is a flat surface that contacts the upper boxwood part of the stub tube 2, and the inner circumferential side of the lower surface is connected to the stub tube 2 with the mechanical seal &-U installed. J] "The control rod drive mechanism housing 4 has a tapered notch so as not to interfere with the welded part 5 of the housing 4.

Also, the upper surface is a tapered surface. A second seal ring 21 is fixed to the inner surface of the sixth cylindrical structure 14 . 6th
The cylindrical structure 14 and the second seal ring 21 are provided with notches similar to those shown in FIGS. 3 and 4. The sixth cylindrical structure 14 is formed by moving the third cylindrical structure 11 and the fifth cylindrical structure 13 in the direction of the reactor pressure vessel lower mirror IC through their respective tapered surfaces. is contracted, and the second seal ring 21 is also contracted. In this way, the second seal ring 21
It is crimped onto the outer surface of the housing 4 to form a seal.

Further, the M5 seal ring 24 is inserted through the groove provided on the upper surface of the sixth cylindrical structure 14 and the tenth cylindrical structure 18.
By crimping them, the intrusion of reactor water from the tapered surface, which is the contact surface of the sixth cylindrical structure 14 and the fifth cylindrical structure 13, is prevented and a seal portion is formed. In this way, the second seal ring 21 and the fifth seal ring 24 form the upper seal portion of the mechanical seal device. Further, the third cylindrical structure 11 and the fifth cylindrical structure 130
Infiltration of reactor water through the gap is caused by
The sixth seal ring 25 is installed on the cylindrical structure 18, and the sixth seal ring 25 is crimped through the eleventh cylindrical structure 19, thereby forming a seal portion and preventing this. The fifth seal ring 24 and the sixth seal ring 25 are crimped onto the threaded portion 11a cut on the inner surface of the third cylindrical structure 11.
This is done by tightening a threaded portion 19a cut on the outer circumferential surface of. For this purpose, a thread is cut on the outer surface of the eleventh cylindrical structure 19 so as to engage with a thread cut on the inner surface of the third cylindrical structure 11. Further, the mechanical seal device main body is fixed using the seventh cylindrical structure 15 in the following manner. No. 9 cylindrical hammered artifact 13
Cut a taper screw 13a on the inner surface of the taper screw 1.
A tapered screw 15a is also cut on the outer surface of the seventh cylindrical structure 15 so as to engage with the seventh cylindrical structure 15. Fifth cylindrical structure 13
The first cylindrical structure 15 is crimped onto the outer surface of the CRD housing 4 by tightening the tapered screw 15a of the seventh cylindrical structure 15 to the tapered screw 13H cut in half. Further, the outer surface of the fifth cylindrical structure 13 and the inner surface of the eleventh cylindrical structure 19, the outer surface of the third cylindrical structure 11, and the inner surface of the ninth cylindrical structure 17 are provided with uneven grooves that engage with each other. By providing this, the pressing force of the seventh cylindrical structure 15 is applied to the fifth cylindrical structure 13 via the tapered screw, and to the eleventh cylindrical structure 2 via the groove on the outer surface of the fifth cylindrical structure 13. transmitted to the proboscis 19, and further,
Since the fifth cylindrical structure 13 and the third cylindrical structure 11 are fixed with screws as described above, the third cylindrical structure 1
1 and is transmitted to the ninth cylindrical structure 17 via the groove on the outer surface of the third cylindrical structure 11, and further, the ninth cylindrical structure 17 and the fourth cylindrical structure 12 are connected as described above. Since it is fixed with a screw, it is transmitted to the fourth cylindrical structure 12.

By tightening the tapered screw of the seventh cylindrical structure 15 in this manner, the mechanical seal device main body can be fixed to the CRD housing 4.

FIG. 2 is a sectional view of the mechanical seal device for CRD repair according to the present invention before the seal portion is tightened. Second
The inner diameter of the first seal ring 20 fixed to the inner surface of the cylindrical structure 10 is dimensioned so as not to interfere with the outer surface of the flange portion of the stub tube 2 during installation, as shown in FIG.

The sixth cylindrical structure 14 and the second seal ring 21 are also cylindrical structures having cutout structures similar to those shown in FIGS. 3 to 6.

FIG. 7 shows the seventh cylindrical structure 1 in the A view of FIG.
5 is shown. The seventh cylindrical structure 15 is provided with a key 26, and the seventh cylindrical structure 1 is
It has a structure that allows 5 screws to be inserted.

FIG. 8 shows the ninth cylindrical structure 1 in the A view of FIG.
7 is shown. The ninth cylindrical structure 17 is provided with a key 27, and has a structure in which the ninth cylindrical structure 17 can be screwed in via the key 27. Furthermore, the 11th
The cylindrical structure 19 is also provided with a similar key.

A screw tightening jig inserted into the PVI is hooked onto each of these keys, so that the screw tightening rotational force from the jig can be transmitted.

In this embodiment, the seal rings 22, 24 and the seal rings 22, 24 are designed on the premise that the adhesion between the tapered surfaces shown in FIG. 1 is not good and leakage of reactor water occurs from between the tapered surfaces. Although a cylindrical structure with pressure is adopted, if the precision-machined surface is machined so that there is no gap between the tapered surfaces, such a seal ring 22.24 or cylindrical structure may be used, depending on the reactor water pressure. It is not necessary to adopt such a structure. In addition, the means for fixing the mechanical seal device main body to the CRD housing does not need to be a tapered screw.
For example, a device for fixing the CRD housing and each mechanical seal device main body by welding each part may be used. However, if permanent repair work on the leakage part is planned for a later date, it will be necessary to remove the mechanical seal device body from the CRD housing 4, so it is necessary to remove it from the CRD housing 4 for ease of attachment and removal. In this case, it is preferable to use a screw as the fixing device as in this embodiment.

〔Effect of the invention〕

As shown in E-H, according to the present invention, a leak near the weld between the housing and the stub tube in the reactor vessel can be fixed by local sealing only near the leak, compared to the conventional whole replacement repair. In addition to being able to prevent leakage, it is not as large as conventional water sealing devices, so it is possible to quickly prevent leakage and to accelerate the time to restart operation in a leak-prevented state.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of a mechanical seal 1st steam train made by a mechanical seal according to an embodiment of the present invention, and Fig. 2 is a longitudinal cross-sectional view of the mechanical seal device shown in Fig. 1 before the seal portion is tightened. 3 is a view of the second cylindrical structure and the first seal ring in FIG. 2 as seen from the DD arrow, FIG. 4 is a view of the same <EE arrow, and FIG. 5 is the second cylinder in FIG. BB arrow view of the structure and the first seal ring, FIG. 6 is also a CC arrow view, and FIG. 7 is the 7th view of FIG. 1.
A view of the cylindrical structure, Fig. 8 is an A view of the 9th cylindrical structure in Fig. 1, Fig. 9 is a view F of Fig. 8, and Fig. 10 is the RPV.
Figure 11 is a cross-sectional view of the main part showing the arrangement of the CRD housing and stub tube in Figure 10. Figure 12 is a cross-sectional view of the lower mirror structure of the conventional CRJ) housing. Fig. 13, which is a cross-sectional view of the gusting portion, is a conceptual diagram of a water sealing device as a conventional sealing means during repair. 1... Reactor pressure vessel, IA... Lower mirror part through hole, I
C... Reactor pressure vessel lower mirror, 2... Stub tube, 3... Welded part, 4... Control rod drive mechanism housing, 5... Welded part, 5A... Sensitized area, 9... First cylindrical structure, 10... Second cylindrical structure, 1
1... Third cylindrical structure, 12... Fourth cylindrical structure, 13... Fifth cylindrical structure, 14... Sixth cylindrical structure, 15... Seventh cylindrical structure. Cylindrical structure, 1
6... Eighth cylindrical structure, 17... Ninth cylindrical structure, 18... Tenth cylindrical structure, 19...
11th cylindrical structure, 20... first seal ring,
21... Second seal ring, 22... Third seal ring, 23... Fourth/- ring, 24... Fifth seal ring, 25... Sixth full ring, 26...
Key, 27...key. 2nd r2

Claims (1)

[Claims] 1. A device comprising a stub tube with one end fixed to the reactor pressure vessel, and a housing passed through the stub tube and welded to the other end of the stub tube, which is supported from the reactor pressure vessel and a first member disposed along the outer periphery of the stub tube; a second member disposed above the other end of the stub tube along the outer periphery of the housing; and an upwardly tapered surface of the first member and the second member. a third member installed through the housing, a fixing device for the third member to the housing provided between the third member and the housing, and a device provided on the inner peripheral side of the first member and the second member. A leak prevention repair device for a housing part of a nuclear reactor vessel, characterized by being equipped with each seal ring.