JPS6154195B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a main steam water seal plug device for closing a main steam nozzle provided in a nuclear reactor pressure vessel.
In more detail, in parallel with the fuel transfer work at the reactor, we will not only have a water seal plug function but also detect leaks in the main steam system so that maintenance and inspection of various main steam system equipment and leakage tests of the main steam system can be performed. Concerning equipment that has the function of a testing device.

Previously, the applicant proposed the main steam water seal plug shown in Figures 1 and 2 as a main steam water seal plug that has advantages such as easy installation and reduced radiation exposure ( (Japanese Patent Publication No. 118697/1983). 1st
2, four main steam nozzles 2 are arranged on the side wall of the pressure vessel 1, and the main steam water sealing plug device A includes various equipment located downstream of the main steam nozzles 2. The main steam nozzle 2 is installed in the pressure vessel 1 for maintenance and inspection (not shown) and for leakage testing on the downstream side of the main steam nozzle 2. This main steam water seal plug device A is installed along the inner wall of the pressure vessel so that it does not obstruct fuel transfer work within the reactor core 7 and can receive the reaction force from the main steam nozzle 2 side during leakage work. A plug unit 13 is disposed at a portion of the ring-shaped frame 3 facing the main steam nozzle 2, and the plug unit 13 can be moved in and out by an air cylinder or the like. A plug 18 is provided.

The installation work of the 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 and remotely controlled by the overhead crane 6. At this time, the positioning of the plug device A in the rotational direction is performed by aligning the guide rod 8 installed inside the pressure vessel 1 with the guide 10 attached to the frame 3, and the vertical positioning is performed by aligning the guide rod 8 installed inside the pressure vessel This is done by placing the frame 3 on the lug 9 provided on the inner wall of the frame 3. After positioning, the plug 18 is attached to the main steam nozzle 2 by remote control, and a test pressure is applied to the main steam nozzle 2 side to perform a leakage test.

This main steam water seal plug device A can be installed and plugged by remote control, so it has the advantage of shortening the installation time and reducing the amount of radiation exposure. It has a configuration in which the reaction force exerted on the plug by the test pressure applied to the steam nozzle side is received by the ring-shaped frame 3 instead of the pressure applied in the pressure vessel as in the past, and the reaction force is applied to the main steam nozzle 1. Since each piece weighs several tens of tons, the frame 3 needs to have considerable rigidity, so it has to be large. For this reason, decontamination after use becomes large-scale, and there is also a problem in that installation work requires exclusive use of the reactor building ceiling crane and the inside of the reactor.

An object of the present invention is to provide a main steam water seal plug device having a structure that allows the main steam water seal plug to be easily attached to the main steam nozzle during regular reactor inspections, and achieves downsizing and labor saving. It is in.

In order to achieve this object, the main steam water seal plug device of the present invention includes a bracket having a plug unit accommodating portion at a position corresponding to the main steam nozzle in the reactor pressure vessel, and a plug unit accommodating portion of the bracket. The plug unit is characterized in that a plug unit with a removably attached plug is removably housed therein.

The details of the present invention will be explained below with reference to the embodiments shown in FIGS. 3 and 4. As shown in FIG. 3, four main steam nozzles 2 are provided on the side wall of the reactor pressure vessel 1 in the same manner as described above, and at positions corresponding to each main steam nozzle 2 in the pressure vessel 1, A bracket 11 having a plug unit receptacle 12 is provided. This embodiment shows an example in which the bracket 11 is formed into a substantially U-shaped cross section with an opening on the top surface, and the plug unit accommodating portion 12 is configured by providing a guide groove 12a on the opposing side wall.

Reference numeral 13 denotes a plug unit on which a plug 18 is removably attached, and the plug unit 13 has a structure in which both sides of the plug unit 13 are fitted so as to be movable up and down along the guide groove 12a. It is housed in a removable manner. Furthermore, a hanger 14 is provided on the top surface of the plug unit 13 to be connected to a hook such as a hanger.

FIG. 4 shows an example of the mounting structure of the plug unit 13 and the plug 18. A cylinder holder 31 is fixedly installed in the frame 30, which is an approximately rectangular hollow body, on the side opposite to the nozzle. A pneumatic cylinder 15 for ejecting and retracting the plug 18 is attached to 31, and the piston rod 16 is connected to the push plate 3, which has a substantially shallow bottomed cylindrical shape.
It is connected to 2. Further, a plurality of guide bushes 33 are fixed to the cylinder holder 31 in parallel with the cylinder 15.
A guide rod 19, which is slidably fitted therein, is coupled to the push plate 32 so that movement of the piston rod 16 always moves the push plate 32 in the correct direction.

The plug 18 also has a shallow cylindrical shape with a bottom like the push plate 32, and its outer diameter is slightly smaller than the inner diameter of the main steam nozzle 2, and its inner diameter is larger than the outer diameter of the push plate 32. In order to allow vertical and horizontal displacement of the plug 18 with respect to the push plate 32, in this embodiment, a floating mechanism 21 consisting of a spring 34 connects the body parts of the two, and the plug 18 and the push plate 32 The bottom portions of the two are connected by a connector 35 that allows relative displacement in the vertical and horizontal directions.

A guide roller 20 is attached to the corner of the tip of the plug 18 to facilitate insertion of the plug 18 into the main steam nozzle 2, and an air port 22 is attached to the outer periphery of the body.
A first gasket 23 is attached that expands with compressed air from the main steam nozzle 2 and comes into close contact with the inner surface of the main steam nozzle 2, and a second gasket 28 is wound around the edge 18a at the rear end of the plug 18. has been done.

Reference numeral 25 denotes a stopper that locks the guide rod 19 after it has been protruded during a leakage test.
It is attached to 6. Also piston rod 36
A cam 26 is attached to a rod 37 that interlocks with the guide rod 19, and when the stopper 25 locks the guide rod 19, the cam 26 operates a limit valve 27 for indicating operation. 38 is a pin that operates a limit valve 39 for indicating the position of the plug 18.

When storing this plug unit 13 in the bracket 11, grasp the hanger 14 with an overhead crane or the hook of a fuel exchanger, lower the plug unit 13 into the plug unit accommodating part 12 of the bracket 11, and lower both sides thereof along the guide groove 12a. and set it. In this case, the axial positioning of the main steam nozzle 2 of the plug unit 13 is done by the guide groove 12a, and the vertical positioning is done by the bottom of the bracket 11.
Due to the precise machining of these parts of the bracket 11, no special alignment of the plug unit 13 is required.

After setting the plug unit, pneumatic cylinder 1
The plug 18 is pushed out into the main steam nozzle 2 by actuating the piston rod 16. At this time, the guide roller 20 and the spring 34
The plug 18 is inserted smoothly by this action. To check the installation of the plug 18, check the pneumatic cylinder 2.
4 and depending on whether or not the limit valve 27 operates. That is, since the stopper 25 can be inserted into the guide bush 33 to lock the guide rod 19 only when the guide rod 19 is in the protruding state, the plug 18 It is possible to confirm that the product is installed. After the plug 18 is attached to the main steam nozzle 2, air pressure is supplied from the air port 22 to expand the first packing 23, thereby bringing the first packing 23 into close contact with the inner surface of the main steam nozzle 2. When the plug 18 is attached to the main steam nozzle 2, the second gasket 28 is compressed between the edge 18a of the plug and the main steam nozzle 2, so these gaskets 23 and 28 provide an effective leak prevention function. This enables 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 downstream of the main steam nozzle 2 from the air port 29 provided in the plug 18. At this time, the plug 18 receives a reaction force that pushes it back inside the pressure vessel 1 due to the differential pressure on both sides, but this reaction force is applied to the stopper 2.
5. It is received by the bracket 11 via the frame 30 of the plug unit 13. After completing the leakage test on the downstream side of the main steam nozzle 2, the air pressure in the first gasket 23 is released and the air pressure in the pneumatic cylinder 2 is
4 to raise the stopper 25 and remove it from the reciprocating path of the guide rod 19, and then move the plug 1
Water is supplied to the downstream side of the main steam nozzle 2 from the water pressure port 40 provided at 8, and the plug 18 is sandwiched to eliminate the differential pressure between the downstream side of the main steam nozzle 2 and the inside of the pressure vessel 1. , the pneumatic cylinder 15 is actuated to withdraw the plug 18 from the main steam nozzle 2.
Whether this pulling operation was performed correctly or not,
This can be confirmed by checking whether the limit valve has been actuated by means of a pin 38 attached to the push plate 32.

After this, the plug unit 13 is connected to the hanger 1.
By hooking the hook of an overhead crane or fuel exchanger to the bracket 4 and lifting it, the bracket 11 can be pulled out and removed by remote control.

Note that the protruding width of the bracket 11 toward the center of the pressure vessel 1 is such that it does not reach the portion corresponding to the outer periphery of the reactor core 7.
Needless to say, 1 does not prevent fuel exchange.

As described above, the main steam water seal plug device of the present invention is provided with a bracket having a plug unit accommodating portion at a position corresponding to the main steam nozzle in the reactor pressure vessel, and in the plug unit accommodating portion of the bracket. Since the device has a structure in which a plug unit with a plug removably attached thereto can be inserted into the device, the size of the device can be significantly reduced compared to known devices having a ring-shaped frame, and manufacturing costs can be reduced. In addition to being compact, the plug unit can be attached and detached by being inserted into and removed from the bracket, making installation extremely easy and contributing to labor savings. In addition, due to the miniaturization of the equipment, installation work can be performed without necessarily using an overhead crane, so the overhead crane can be used for other maintenance and inspection work, making it possible to shorten the time required for maintenance and inspection, and decontamination. Work is also made easier.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a known main steam water seal plug device, FIG. 2 is a sectional view thereof, FIG. 3 is a plan view showing an embodiment of the main steam water seal plug device of the present invention, and FIG. is a sectional view taken along line E-E. 1...Pressure vessel, 2...Main steam nozzle, 11...
...Bracket, 12...Plug unit housing section,
12a... Guide groove, 13... Plug unit,
18...Plug.

Claims (1)

[Claims] 1. A bracket having a plug unit accommodating portion is provided at a position corresponding to the main steam nozzle in the reactor pressure vessel, and a plug unit with a plug removably attached to the plug unit accommodating portion of the bracket is provided. A main steam water seal plug device characterized by having a configuration in which it is housed in a removable manner. 2. The plug unit accommodating portion is constituted by guide grooves formed vertically on opposing surfaces of both side walls of a bracket having a substantially U-shaped upper opening. Main steam water plug device.