JPH0115840B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a main steam nozzle water seal plug that closes a main steam nozzle provided in a nuclear reactor pressure vessel, and more specifically relates to fuel transfer work in a nuclear reactor. This project relates to improvements to the main steam nozzle water seal plug mechanism for carrying out maintenance and inspection of various equipment in the main steam system and leakage tests in the main steam system in parallel with movement and fuel exchange within the reactor core.

[Background of the invention]

The present applicant previously published Japanese Patent Application Laid-open No. 53-118697,
We have proposed a main steam nozzle water seal plug that has advantages such as easy installation work and reduced radiation exposure. This will be explained with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view showing the main steam water seal plug device, and FIG. 2 is a vertical cross-sectional view of the frame shown in FIG. 1 in a state where it is attached. In the figure, 1 is a pressure vessel;
Four main steam nozzles 2 are arranged on the side wall of the pressure vessel 1. A is a main steam water seal plug device, which is used to perform maintenance and inspection of various equipment (not shown) located downstream of the main steam nozzle 2 and to perform leakage tests downstream of the main steam nozzle 2. It is installed in This main steam water seal plug device A is
The inner wall of the pressure vessel 1 is designed so that the main steam water sealing plug device A does not interfere with the fuel movement work in the reactor core 7 and can receive the reaction force from the outside of the main steam nozzle 2 during the leak test work. It has a ring-shaped frame 3 that is housed in the section. frame 3
A plug unit 13 is disposed at a location facing the main steam nozzle 2, and a plug 18 is attached to the plug unit 13 so as to be retractable by an air cylinder or the like (not shown). Water pressure port piping 16 and air port piping 17 shown in FIG. 4 of the embodiment are provided, but illustration thereof is omitted.

The installation work of this main steam water seal plug device A is carried out by hanging the hanger 5 of the overhead crane 6 on the hanger 4 attached to the frame 3 as shown in FIG.
This is done remotely using an overhead crane 6. At this time, the main steam water seal plug device A is positioned in the circumferential direction by a guide rod 8 installed on the inner wall of the pressure vessel 1 and a guide 1 attached to the frame 3.
This is done by aligning the In addition, the vertical alignment is performed using the pressure vessel 1.
After positioning, the plug 18 is attached to the main steam nozzle 2 by remote control, and when testing the main steam nozzle 2 for leakage, the frame 3 is placed on the lug 9 fixed to the inner wall of the main steam nozzle 2. Test pressure is now applied.

This main steam water seal plug device A is capable of attaching and detaching the plug 18 by remote control, so it has the advantage of shortening the operation time and reducing the amount of radiation exposure. However, the plug 18 based on the test pressure applied to the main steam nozzle 2 side during the leak test
The reaction force acting on the main steam nozzle 2 is not the pressure applied inside the pressure vessel 1 as in the conventional case.
Since each piece weighs several tens of tons, the frame 3 needs to have great rigidity, and therefore has to be large. For this reason, decontamination after use becomes large-scale, and there is also the problem that an overhead crane of the reactor building is used for installation and removal work, and the inside of the reactor is occupied as space for the frame 3. Furthermore, in existing plants,
If this main steam water seal plug device A is used, it has disadvantages such as blocking a part of the reactor core, and it is expected that the reactor core will become wider and the reactor pressure vessel will become narrower in the future.
Due to the periodic inspection process, etc., it is considered that the main steam water seal plug device A cannot handle this problem.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and provides a main steam nozzle water-sealing plug mechanism that allows simple and easy operation of attaching and detaching the plug to the main steam nozzle, is miniaturized, and facilitates maintenance and inspection of equipment in the reactor. It is intended for this purpose.

[Summary of the Invention] The main steam nozzle water seal plug mechanism of the present invention comprises: a plug that is detachably attached to a main steam nozzle attached to a pressure vessel of a nuclear reactor from inside the pressure vessel; A water pressure port pipe that communicates between the inside and outside, and packing that seals the outer periphery of the plug to the inner wall of the pressure vessel and the inner wall of the main steam nozzle, respectively. a bracket that is provided on the inner wall of the pressure vessel at a position where the plug can freely pass through the main steam nozzle; The device is characterized in that a fixing means is provided for removably fixing the device to the device.

[Embodiments of the invention]

The main steam nozzle water seal plug mechanism of the present invention is as follows:
Using this embodiment, parts that are the same as those in the prior art are denoted by the same reference numerals, and explanations of the structures of the same parts will be omitted and will be explained with reference to FIGS. 3 and 4. 3A is a detailed view of the same part as B in FIG. 1, B is a front view of the bracket and plug in A, and FIG. 4 is an enlarged view taken in the direction indicated by the - arrow in FIG. In the figure, brackets 11 are fixed along the vertical direction at positions on both sides of the opening of the main steam nozzle 2 on the inner wall of the pressure vessel 1, and each bracket 11 is a short piece bent horizontally on the left and right opposite sides of the lower end. It has an L-shape and forms a plug storage part. The plug 18 can be attached and detached from the radial direction, and slide grooves 12 into which wedges 15a are inserted are formed on opposing surfaces of the brackets 11, 11, respectively. Both sides of the plug 18 are movable horizontally along the bracket 11, so that the plug 18 can be attached to and removed from the plug housing. Further, a hanger 14 that is latched to a hook such as a hanger is provided at the bottom of the plug 18, and a water pressure port piping 16 that also serves as an air port is attached so that the inside and outside of the plug 18 can communicate with each other. 1
6 can also be used as an operation pole for inserting the plug 18. In this case, the water pressure port piping 16 is grasped from the floor using a long rod and remotely controlled.

FIG. 4 shows the plug 18 installed,
The plug 18 is formed into a shallow cylindrical shape with a bottom, and its outer diameter is formed to be slightly smaller than the opening inner diameter of the main steam nozzle 2. The plug 18 has a corner at its tip that is inserted into the main steam nozzle 2. A guide roller 19 is attached so that the insertion work can be performed smoothly. Further, an air port pipe 17 is provided on the outer periphery of the tip side of the plug 18 facing the inner periphery of the main steam nozzle 2.
A first packing 20 is attached that is expanded by compressed air from the main steam nozzle 2 and is brought into close contact with the inner circumferential surface of the main steam nozzle 2. The portion of the rear end of the plug 18 that is larger in diameter than the opening of the main steam nozzle 2 is the main steam nozzle 2.
The inner wall of the pressure vessel 1 around the opening is sealed by a second packing 21. A fixed wedge 15 is formed on the back side of the plug 18 opposite to the side facing the main steam nozzle 2 . Then, when the wedge 15a contacts the fixed wedge 15 from above and is fitted into the slide groove 12 formed in the bracket 11, the second packing 21 of the plug 18 installed in the plug accommodating portion formed in the bracket 11 is deformed. The degree of adhesion has been enhanced.

When the plug 18 is installed in the plug storage area, hang the hanger 14 with the hook of an overhead crane or fuel exchanger, move the plug 18 horizontally to the plug storage area of the bracket 11 using the bracket 11 as a guide, and then attach the air port By using the hydraulic piping 16 which also serves as an operating pole, it can be smoothly attached to the bracket 11 and the main steam nozzle 2. Then, by tightly fitting the wedge 15a into the slide groove 12 while sliding it on the surface of the fixed wedge 15, the second packing 21 is compressed due to the wedge effect between it and the fixed wedge 15 fixed to the plug 18. and is tightly attached to the inner wall surface of the pressure vessel 1. Plug 1
8 to the main steam nozzle 2, connect the air port piping 1
By sending compressed air from 7 to the back of the first packing 20 and expanding it, the first packing 20 can be brought into close contact with the inner peripheral surface of the main steam nozzle 2. These first and second packings 20 and 21 provide an effective leakage prevention function and enable maintenance and inspection work on the downstream side of the main steam nozzle 2.

When performing a leakage test on various devices installed downstream of the main steam nozzle 2, compressed air is sent to the downstream side of the main steam nozzle 2 from the water pressure port pipe 16, which also serves as an air port, provided in the plug 18. At this time, the plug 18 is moved to the pressure vessel 1 due to the differential pressure on both sides.
However, this reaction force is received by the bracket 11 via the wedge 15a. After the leakage test on the downstream side of the main steam nozzle 2 is completed, the air pressure of the first packing 20 is released, and the plug 1
Water is supplied to the downstream side of the main steam nozzle 2 from the water pressure port piping 16 provided at Remove the wedge 15a and pull it upward. Thereafter, the plug 18 can be pulled out from the bracket 11 and removed by remote control by being hooked to the hanger 14 and the hook of an overhead crane or a fuel exchanger. still,
The amount of protrusion of the bracket 11 toward the center of the pressure vessel 1 is designed so that it does not reach the outer periphery of the core 7 in order to facilitate inspection of the equipment inside the reactor. Of course, it is not a hindrance. Further, the removed plug 18 is stored on the floor or the like.

As described above, the main steam nozzle water seal plug device of this embodiment is provided with brackets that form plug storage areas on the inner wall of the pressure vessel at positions on both sides of the opening of the main steam nozzle of the pressure vessel, and the plugs are installed in the plug storage areas. Since it is constructed so that it can be attached and detached from the radial direction and the plug is fixed to the bracket via a wedge after attachment, it can be significantly smaller than the conventional structure with a ring-shaped frame, reducing manufacturing costs and improving economic efficiency.
It also becomes easier to inspect the equipment inside the furnace. In addition, the plug can be easily attached and detached from the bracket, and
Due to the miniaturization, it is not necessary to use an overhead crane, so the overhead crane can be used for other maintenance and inspection work, reducing the time and man-hours required for maintenance and inspection, and making decontamination work easier.

〔Effect of the invention〕

As described above, the main steam nozzle plug mechanism of the present invention can be miniaturized, and the operation of attaching and detaching the plug to the main steam nozzle is easy, making it easy to inspect the equipment inside the furnace, improving economic efficiency, and reducing the number of work steps. It is effective.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a conventional main steam nozzle water seal plug mechanism, Fig. 2 is a longitudinal sectional view of the frame attached state of Fig. 1, and Fig. 3 is an implementation of the main steam nozzle water seal plug mechanism of the present invention. To illustrate an example, A is an enlarged view of the same part as B in FIG. 1, B is a front view of the bracket and plug in A, and FIG. 4 is an enlarged cross-sectional view taken along the - arrow in FIG. 3A. 1...Pressure vessel, 2...Main steam nozzle, 11...
... Bracket, 12 ... Slide groove, 15 ... Fixed wedge, 15a ... Wedge, 16 ... Water pressure port piping, 18
...Plug, 20...First packing, 21...
2nd patch king.

Claims (1)

[Claims] 1. A plug that is detachably attached to a main steam nozzle attached to a pressure vessel of a nuclear reactor from the inside of the pressure vessel, a water pressure port piping provided on the plug that communicates the inside and outside, and a water pressure port that connects the outer periphery of the plug to the above pressure The plug is moved in the radial direction of the pressure vessel and is attached to and removed from the main steam nozzle, and the main steam nozzle is provided with sealing packing on the inner wall of the pressure vessel and the inner wall of the main steam nozzle. A bracket is provided at a position where the plug can freely pass through at the opening position of the steam nozzle, and a fixing means for engaging the plug with the bracket and removably fixing the plug to the main steam nozzle. A main steam nozzle water seal plug mechanism featuring: