JPH02147896A - Water seal device for replacing operation of control rod driving mechanism housing - Google Patents

Abstract

PURPOSE:To secure a water seal area required to replace a control rod driving mechanism(CRD) housing and a stub tube by providing a diameter increasing mechanism to the lower part of a water seal device main body. CONSTITUTION:The water seal device 11 consists of an upper part 11A and a lower part 11B in cylindrical structure, the upper part 11A is in normal cylindrical structure, and the lower part 11B is provided with the diameter increasing mechanism 12. Then when the device 11 is installed, the device 11 is passed through an upper grid plate 4 and a reactor core support part 5 from the upper part of a nuclear reactor pressure vessel (RPV) and the diameter is increased by the mechanism 12 after the lower part 11B passes through the reactor core support plate 5, thereby seating the device 11 on the lower mirror 7 of the RPV in the state. Consequently, the CRD housing 2, stub tube 3, and buttering 6 are housed in the lower part 11B to secure the expanded water seal area required for the CRD housing replacing operation.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a water seal device used for replacing a control rod drive mechanism housing in a nuclear reactor pressure vessel during the service life of a nuclear power plant, and in particular, The present invention relates to a water sealing device suitable for sealing the periphery of a control rod drive 111M housing from reactor water and providing a good working space.

[Conventional technology]

A cylindrical stub tube is welded to the inner surface of the reactor pressure vessel (hereinafter referred to as RPV), and a cylindrical control rod drive housing (hereinafter referred to as CRDR housing) is inserted into this stub tube and penetrates the wall of the RPV. It is depressed and welded to the stub tube. This CHD housing and stub tube replacement work is carried out on the RPV in order to reduce the radiation dose around the RPV in order to ensure work safety such as radiation.
The replacement work is carried out with the RPV filled with water, and the water is used to stop radiation from the reactor core. Some processes cannot be carried out underwater.

For this reason, it is necessary to fill the RPV with water and remove water only around the CRDR housing and stub tube to be acquired. Install a sealing device. After installation, the water seal device drains the water inside and seals the space around the CRDR housing and stub tube to be replaced from RPV water.

FIG. 15 shows an outline of a conventional water seal device.

When installing the water seal device 1, remove the equipment inside the RPV (dryer, shroud head, control rod guide tube, etc.) and the fuel assembly, and then from the top of the RPV, remove the lattice of the upper lattice plate 4 and the core support plate 5. Pass through the CR plan guide large hole 5A, seat it on the RPV lower mirror 7, and set it around the CHD housing 2 and stub tube 3. The water sealing device 1 consists of a cylindrical structure main body, which separates the outside and the inside, drains the water inside by a pump 8, and seals around the CRDR housing 2 and stub tube from RPV water. The part having the sealing function is the part of the lower end of the water sealing device 1 that abuts against the RPV lower mirror part.

Here, because the conventional water seal device consists of a pure cylindrical structure main body, and the water seal device ξ has to pass through the CR plan guide large hole 5A of the core support plate 5 from the top of the RPV, the water seal device The outer diameter is the CRR of the core support plate.
It cannot be made larger than the inner tube hole diameter, and CHD will inevitably occur.
The sealing area around the housing 2 and stub tube 3 is also narrower. For this reason, the sealing portion 9 of the water sealing device with the lower mirror portion at the tip rests on the welded portion around the stub tube, that is, the battering (sensual portion) 6.

Currently, in the CHD housing and stub tube replacement work, repair of the buttering 6 around the stub tube is being considered, and it is necessary to make the water seal area larger than the buttering 6.

FIG. 16 to FIG. 18 schematically show the structure of the seal portion at the lower end of a conventional water seal device. Water sealing device: A sealing rubber 10 is attached to the entire circumference of the tip of the lower end. As shown in FIG. 17, the sealing rubber 10 is pressed against the inner surface of the rtpv lower mirror 7 by installing the water sealing device 1. In addition, the seal rubber 10 is further pressed against the lower mirror by air pressure 12, as shown in FIG. 18, and performs a water sealing function.

The above-mentioned water sealing device for the CI'LD housing and stub tube is described in Japanese Patent Application No. 58-66764.

[Problem to be solved by the invention]

As mentioned above, the area required for the water seal around the CRDR housing and stub tube in the CHD housing and stub tube replacement work needs to be wider than the buttering (built-up part) around the stub tube.

However, the conventional device described above has a problem in that the water sealing area is limited due to the structure and installation of the water sealing device, and the required area cannot be sealed.

An object of the present invention is to provide a water seal device for control rod drive mechanism housing replacement work that can obtain a water seal area necessary for replacement work of a CHD housing and stub tube.

Another object of the present invention is to provide a water sealing device for control rod drive IR treetop housing replacement work that can ensure sufficient sealing performance.

[Failure to solve the problem]

The above object is achieved by providing the lower part of the cylindrical body with an enlarged diameter tf% for enlarging the water sealing area.

Preferably, a suction negative pressure type sealing means is provided at the lower end of the cylindrical structure main body having the widened diameter a.

The expanded diameter M1 treetop can be configured with a plurality of variable legs that can be opened and closed in the radial direction, for example. Further, the diameter expanding mechanism is linked to a plurality of cylindrical segments or side frames that are rotatable about a rotation axis located inside, and to a lower end of the side frames, and is expanded by being pushed and expanded by movement of the side frames. It can be constructed with a frame structure consisting of a lower frame and a lower frame.

Further, the above object is achieved by providing a suction negative pressure type sealing means at the lower end of the cylindrical structure main body.

[Effect]

In the present invention configured in this way, when the lower part of the cylindrical structure main body of the water seal device passes through the CR guide water hole of the core support plate during attachment and detachment of the device, the diameter of the hole is smaller than the diameter of the hole and does not impede passage. After the lower end of the round body is seated and installed on the lower mirror, it is expanded by the diameter expanding mechanism to expand the water seal area around the CHD housing and stub tube. This allows the water seal device to
While setting from above V through the lattice of the upper lattice plate and the hole of the CRR inner tube of the core support plate, after setting, seal the area around the CHD housing and stub tube that is wider than the hole diameter of the CRR inner tube of the core support plate. This makes it possible to include the buttering (built-up part) around the stub tube that is required in the water seal area.

If a suction negative pressure type sealing means is provided at the lower end of the cylindrical structure body of the water sealing device, sufficient sealing performance can be ensured even without pressure from the cylindrical structure body, so the diameter expansion mechanism described above can be adopted. This makes it easier to ensure sealing performance.

〔Example〕

Hereinafter, a practical example of the present invention will be explained with reference to FIGS. 1 to 5.

In FIG. 1, the cylindrical structure main body of the water seal device 11 of this embodiment includes an upper portion 11A located above the circumference of the CRDR housing 2 and the stub tube 3 during use, and a lower portion 11A located below the upper portion 11A. , 8, the upper part 11A is a normal cylinder tMm, and the lower part 11A is a normal cylinder tMm.
B has a cylindrical structure equipped with a diameter expanding mechanism 12 for expanding the diameter.

A seal portion 16 is provided at the lower end of the lower portion 11B.

The water seal device 11 configured in this way is set by being seated on the lower mirror 7 of the RPV through the lattice of the upper lattice plate 4, the CR guide large hole 5A of the core support plate 5, and the lower mirror 7 of the RPV. At this time, after the lower portion 11B passes through the core support plate 5, its diameter is expanded by the diameter expanding mechanism 12, and in this state it is seated on the RPV lower mirror.

As a result, the CH
In addition to the D housing 2 and the stub tube 3, the butter ring 6 is housed, making it possible to secure an expanded water seal area required for CHD housing replacement work.

The specific configuration of the diameter expanding mechanism 12 will be explained with reference to FIGS. 2 to 5. The diameter expanding mechanism 12 is pivotally connected to the lower end of the upper portion 11A so as to be openable and closable in the radial direction, and has a plurality of variable legs 13 arranged at equal intervals in the circumferential direction.
is biased in the radially outward opening direction. Expanded diameter fl! After the JIIi 12 passes through the CR guide large hole 5A of the core support plate 5 in the closed state as shown in FIG. Open as shown and enlarge the diameter.

The enlarged diameter fit M12 is sealed by wrapping the elastic membrane 15 around the entire circumference of the variable leg 13.

This elastic membrane 15 is wound continuously from the variable leg 13 to the lower end portion of the upper portion 11A, and is fixed with bands 51 and 52 to prevent water leakage due to structural discontinuity between the expanded diameter t[12 and the upper portion 11A. We are trying to prevent this from occurring. A closing lever 50 is engaged with the variable leg 13. When the variable leg 13 is in the open position, the closing lever 50 presses the elastic membrane 15 between the bands 51, 51 and protrudes outward, as shown in FIG. As a result, when the water seal device is pulled up, when the enlarged diameter aJM12 passes through the large CR guide hole 5A of the core support plate, the closing lever hits the wall of the hole 5A, presses the variable leg 13, and closes the enlarged diameter fiM12. At the tip of the variable leg 13, there is a water seal device lower part 11B and an RPV.
A seal rubber 16 is attached to seal between the lower mirror and the lower mirror.

4 and 5 show the variable leg 13 of the water seal device diameter expansion mechanism 12 and the water seal elasticity Jl! 15, Lower end seal rubber 1
6 shows an outline of the arrangement state of No. 6. The variable legs 13 are arranged in a circle at equal intervals, the water seal elastic membrane 15 is wrapped around the entire circumference, and the seal rubber 16 is attached to the tip of the variable leg 13 so as to connect each variable leg 13 (-f). and seal the entire circumference.

Here, in this diameter expansion mechanism 12, the seal rubber 16 is crimped to the lower mirror by the variable leg 13, so the pressing force between it and the RPV lower mirror 7 is small except for the part on which the variable leg rests, and the seal rubber 16 is sufficiently crimped. It is expected that this will not be possible. As a countermeasure against this problem, the structure of the seal rubber 16 can be of a suction negative pressure type as shown in FIGS. 6 to 8. That is, seal rubber 1
5, as shown in FIG. 6, with both ends expanding outward, and after being crimped onto the RPV lower mirror as shown in FIG. Depressurize the space between the RPV lower mirror and
Water sealing is performed using the water pressure 18, and as a result, good sealing performance can be maintained all around the seal rubber.

The enlarged diameter R side of a water seal device according to another embodiment of the present invention will be explained with reference to FIGS. 9 to 12. In the above embodiment, a structure consisting of a plurality of variable legs was used as the diameter expansion mechanism, but in this embodiment ρI, a plurality of rotatable cylindrical segments are used instead of variable legs, and the size of the cylinder formed is adjusted as required. shall be larger than the water seal area.

That is, in FIGS. 9 and 10, the expanded diameter f of this embodiment
The i4711 has a large number of cylindrical segments made by equally dividing a cylinder into a plurality of parts in the circumferential direction, and each cylindrical segment is connected to the rotating shaft 2 by a bracket 20 inside the cylindrical shape.
A gear 22 is attached to the 0-rotation shaft 21 which is fixed at 1 and can rotate around this rotation shaft 21, and this gear 22 has a gear 23 concentric with the cylindrical shape of one cylindrical segment. When the gears mesh and the gear 23 applies rotation to the gear 22, one cylindrical segment is rotated. By such rotation of one cylindrical segment, the diameter expansion mechanism is changed from an expanded state as shown in FIGS. 9 and 10 to a contracted state as shown in FIGS. 11 and 12. The diameter can be changed depending on the state.

In this embodiment as well, as in the first embodiment, the inside of the sealing device can be water-sealed by wrapping an elastic membrane for sealing around the outer periphery of one cylindrical segment and covering the entire circumference of the lower 41 with sealing rubber. . In this case, in this embodiment, the RPV lower mirror of the seal rubber is crimped using the diameter expander f.
Since δ has a cylindrical shape, the sealing is performed almost uniformly around the entire circumference, and higher sealing performance can be obtained.

Still another embodiment of the enlarged diameter v1 structure of the present invention is shown in FIG. 13 and FIG. The frame lateral path is made up of an upper frame 25 linked in a ring shape to the +, and a lower frame 26 linked in a link shape to the lower end of the side frame 24, and as the movable frame 24 moves, the lower frame 2
6 is pushed out to fulfill the function of expanding the seal area.
By wrapping an elastic membrane for sealing around the outer periphery of the sealing device and applying sealing rubber around the entire lower end, the inside of the sealing device can be water-sealed. Furthermore, since the lower frame 26 connects the entire lower end of the side frame 24, the seal rubber is crimped to the RPV lower weight almost uniformly over the entire circumference, resulting in high sealing performance.

〔Effect of the invention〕

According to the present invention, it is possible to secure a sufficient water sealing area in the range where water sealing is required for the heat extraction target part during CHD housing and stub tube replacement work, and the sealing performance can also be maintained. It is possible to obtain a hole that improves workability in replacing the CHD housing and stub tube.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a water seal device according to an embodiment of the present invention, FIG. 2 is an enlarged detailed view of the diameter expanding mechanism of the water seal device, and FIG. 3 is an enlarged diagram of the diameter expanding mechanism of the same water seal device. Fig. 4 is a cross-sectional view of the diameter expanding mechanism;
Fig. 5 is an enlarged view of the lower end portion of the diameter expanding mechanism;
7 and 8 are diagrams showing the structure of the seal rubber attached to the lower end of the enlarged diameter tR scoop, and FIG. 9 is a partial perspective view of the enlarged diameter R scoop according to another embodiment of the present invention. and the first
Figure 0 is a top view of the same diameter expansion mechanism, and Figure 11 is the same diameter expansion mechanism a.
FIG. 12 is a top view of the enlarged diameter 11 in the contracted state, and FIG. 13 is a lateral side view of the enlarged diameter a according to still another embodiment of the present invention. FIGS. 14(A) and 14(B) are a side view and a top view showing the enlarged diameter W1, respectively, and FIG. 15 is a schematic configuration diagram of a conventional water seal device. , FIG. 16, FIG. 17, and FIG. 18 are diagrams showing the structure of conventional seal rubber. Explanation of symbols 2... Control rod drive R Treetop housing 3... Stub tube 4... Upper grid plate 5... Core support plate 7... Reactor pressure vessel lower mirror 11... Expanded diameter R 11B Lower part 13 Variable leg 16 Seal rubber (sealing means) 19 Cylindrical segment 24 Side frame 26 Lower frame Figure 1

Claims (6)

[Claims] (1) A cylindrical stub tube welded to the inner surface of the reactor pressure vessel, and a cylindrical control inserted into the stub tube through the wall of the pressure vessel and welded to the stub tube. When replacing the rod drive mechanism housing, the control rod drive mechanism housing includes a cylindrical structure body that is inserted from the upper part of the pressure vessel through the upper grid plate and the core support plate and seals the periphery of the control rod drive mechanism housing and the stub tube from reactor water. A water sealing device, characterized in that a diameter expanding mechanism for enlarging a water sealing area is provided in a lower portion of the cylindrical structure main body. (2) Claim 1 characterized in that a suction negative pressure type sealing means is provided at the lower end of the cylindrical structure body provided with the diameter expansion mechanism.
Water sealing device as described. (3) The water seal device according to claim 1, wherein the diameter expanding mechanism is comprised of a plurality of variable legs that can be opened and closed in a radial direction. (4) The water seal device according to claim 1, wherein the diameter expanding mechanism is comprised of a plurality of cylindrical segments that are rotatable about a rotating shaft located on the inner surface. (5) A claim characterized in that the diameter expanding mechanism has a frame structure consisting of a side frame and a lower frame that is linked to the lower end of the side frame and is expanded by movement of the side frame. The water seal device according to item 1. (6) A cylindrical stub tube welded to the inner surface of the reactor pressure vessel, and a cylindrical control inserted into the stub tube through the wall of the pressure vessel and welded to the stub tube. When replacing the rod drive mechanism housing, the control rod drive mechanism housing includes a cylindrical structure body that is inserted from the upper part of the pressure vessel through the upper grid plate and the core support plate and seals the periphery of the control rod drive mechanism housing and the stub tube from reactor water. A water sealing device, characterized in that a suction negative pressure type sealing means is provided at the lower end of the cylindrical structure main body.