JPH0672941B2 - Main steam nozzle closing device for reactor pressure vessel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention relates to a boiling water reactor (hereinafter referred to as BWR),
The present invention relates to an improvement of a main steam nozzle closing device for a reactor pressure vessel that closes a main steam nozzle of the reactor pressure vessel.

(Prior Art) Generally, in a nuclear power plant and the like, maintenance and inspection are performed by stopping the nuclear reactor at the time of periodic inspection. In order to perform this maintenance and inspection work up to the upper part of the reactor pressure vessel with water filling, in parallel with the in-reactor work such as refueling, the nozzle of the main steam pipe is closed and the reactor of the reactor pressure vessel is closed. It is necessary to prevent water from flowing into the main steam pipe so that maintenance and inspection work of the main steam isolation valve provided in the main steam pipe can be performed in parallel. A main steam nozzle closing device is used for closing the main steam nozzle at that time. This main steam nozzle closing device not only has the function of preventing reactor water from leaking from the reactor pressure vessel side to the main steam piping side, but also leaks the main steam isolation valve after maintenance and inspection of the main steam isolation valve, etc. For the purpose of testing, it is necessary to have a function to withstand the reverse pressure and maintain the main steam nozzle closed state without flowing out of the main steam nozzle and flowing into the furnace even if the fluid is pressed into the main steam pipe. .

Therefore, the configuration of a conventional main steam nozzle closing device will be described with reference to FIG. In the figure, reference numeral 101 is a reactor pressure vessel, and a main steam nozzle 102 is formed in the reactor pressure vessel 101. There are two main steam nozzles 102, and two main steam nozzles 102 are installed. The two main steam nozzles 102 forming one set are installed to face each other on the diameter of the reactor pressure vessel 101. Each main steam nozzle 102 has a straight tube shape and is closed by a main steam nozzle closing device 103 . That is, the right cylindrical support 104 of the main steam nozzle closing device 103 is located inside the reactor pressure vessel 101 and is the main steam nozzle.
It is inserted into the inside of the bearing 102, and watertightness and airtightness are maintained by interposing annular sealing members 105 and 106 between the outer peripheral surface of the bearing 104 and the inner peripheral surface of the main steam nozzle 102. . Further, the flange 107 provided at the base of the support 104 receives the water pressure from the reactor pressure vessel 101 toward the main steam pipe 109, abuts the inner wall surface of the reactor pressure vessel 101 to support the closing device 103 , On the other hand, with respect to the fluid pressure (reverse pressure) of water, air, or the like, which is directed from the main steam pipe 109 side into the reactor pressure vessel 101, a back pressure support ring (or cross beam) fixed in the reactor pressure vessel 101 is provided. The blocking device 103 prevents the clogging device 103 from jumping out into the reactor pressure vessel 101.

The above configuration has the following problems. Fluid pressure (reverse pressure) from the main steam pipe 109 side toward the reactor pressure vessel 101
In order to maintain the closed state even with respect to, it is necessary to install the back pressure support ring 108 in the reactor pressure vessel 101 as described above, but when the back pressure support ring 108 is installed, Maintenance of in-furnace equipment such as jet pumps
The above-mentioned back pressure support ring 108 interferes with the work at the time of inspection or during the inspection during the use period, which makes the work difficult, and it is expected that the back pressure support ring 108 will be damaged during the work, and the improvement thereof is expected. Was requested.

(Problems to be Solved by the Invention) The present invention has been made on the basis of the above points, and its object is to ensure that the plug body comes out of the main steam nozzle without using a support ring or the like. Another object of the present invention is to provide a main steam nozzle closing device for a reactor pressure vessel that can prevent the above.

[Structure of the Invention] (Means for Solving Problems) That is, the present invention relates to a hollow cylindrical plug body to be inserted into a main steam nozzle of a reactor pressure vessel from the reactor pressure vessel side, and a plug body inside the plug body. A drive cylinder provided with a piston rod protruding from the tip of the plug body, a drive fluid supply pipe and a withdrawal pipe for supplying a drive fluid to the drive cylinder to move the piston rod forward and backward, and at the tip of the piston rod. A lock plug provided with a wedge-shaped cross section, a wedge body having an engagement surface for engaging with a side surface of the lock plug and abutting against the inner surface of the main steam nozzle by the backward movement of the piston rod, and a rear portion of the plug body. A flange provided at an end to prevent the plug body from entering the main steam nozzle, a seal member provided on the outer periphery of the plug body, and And a backup piston that is provided on the tip side of the plug body and that urges the piston rod toward the reactor pressure vessel side by receiving the pressure of the fluid that has flowed into the plug body from the through hole. To do.

(Operation) That is, in the present invention, when the piston rod of the drive cylinder moves backward, the wedge body provided at the tip of the plug body moves in the radial direction of the main steam nozzle and contacts the inner surface of the main steam nozzle. Therefore, it is possible to prevent the plug body from coming out of the main steam nozzle without using a support ring, etc., and it is possible to perform maintenance work of the jet pump etc. in parallel with maintenance work of the main steam isolation valve. it can. A backup piston is provided inside the plug body to urge the piston rod toward the reactor pressure vessel by receiving the pressure of the fluid flowing into the plug body through the through hole provided at the tip side of the plug body. Therefore, even if the drive cylinder loses its function, it is possible to prevent the plug body from coming out of the main steam nozzle due to the fluid pressure from the main steam pipe side.

(Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a view showing a state in which the main steam nozzle closing device according to this embodiment is attached to the main steam nozzle. In the figure, reference numeral 1 is a reactor pressure vessel, and a main steam nozzle 2 is fixed to the reactor pressure vessel 1. The main steam nozzle 2 has a tapered portion 2a whose inner diameter gradually increases from the inlet to the back, that is, from the portion opened to the reactor pressure vessel 1 to the portion opened to the main steam pipe 3. It has a substantially trumpet shape. It is the plug body 4 of the main steam nozzle closing body that directly closes the main steam nozzle 2, and the plug body 4 is moved back and forth from the inside of the reactor pressure vessel 1 to be attached / detached.
The plug body attaching / detaching device 5 shown in FIGS. The configuration of the plug body 4 will be described below.

The plug body 4 has a cylindrical shape whose outer diameter is slightly smaller than the inlet diameter of the main steam nozzle 2. Further, the inside of the plug body 4 is hollow, and a drive cylinder 5 is installed inside thereof. A piston 5a is slidably accommodated in the drive cylinder 5, and a lock plug 6 is connected to the tip of a piston rod 5b fixed to the piston 5a. By moving, the wedge body 7 is driven in the radial direction of the main steam nozzle 2. A drive fluid supply pipe 8a and a withdrawal pipe 8b are connected to the drive cylinder 5. Driving fluid supply piping
By supplying the driving fluid to the driving cylinder 5 via 8a, the piston 5a and the lock plug 6 slide in the direction indicated by X in the drawing, which causes the wedge body 7 to move in the direction indicated by Y in the drawing as shown in FIG. Driven in the direction indicated by. The wedge body 7 is installed at four locations in the orthogonal direction, and the key 7a formed at the end is fitted into the key groove 4a of the plug body 4 as shown in FIGS. 4 and 5. ing. A flange (locking portion) 9 having a diameter larger than the inner diameter of the main steam nozzle 2 is fixed to the base portion (inside the reactor pressure vessel 1) of the plug body 4. A seal ring 10 is mounted between the flange 9 and the main steam nozzle 2. Further, the plug body 4 has an annular groove.
11 is formed, and another seal ring 12 is attached to the annular groove 11.

Next, the plug body attaching / detaching device 5 will be described. As shown in FIGS. 3 and 4, the plug body attaching / detaching device 5 is provided with two beams 24 connected in an X shape and the plug bodies 4 provided at the tip of each beam 24 so as to be detachably supported. Support mechanism 25,
It is composed of a drive mechanism 26 for moving the plug body 4 together with the support mechanism 25 into and out of the main steam nozzle 2. The drive mechanism 26 directs the beam toward the main steam nozzle 2.
It is composed of a hydraulic cylinder 27 fixed to 24 and a plunger 28. The support mechanism 25 is the plunger 28.
The carriage 29 fixed to the tip of the plug body 4 and the L-shaped bracket 30 projecting from both side surfaces of the plug body 4 are inserted from above,
An eyeglass member that integrally connects the plug body 4 and the carriage 29.
It consists of 31 and. The trolley 29 has wheels for gliding.
32 and the guide piece 33 are attached. And the beam
There are four eyebolts 34 installed on the 24.
Hang a hanging hook (not shown) on each eyebolt 34.

The operation will be described based on the above configuration. First, the blockage of the main steam nozzle 2 will be described. The plug body attaching / detaching device 5 is placed on the floor near the reactor pressure vessel 1. Next trolley
29 Attach the eyeglass member 31 to the bracket 30 of the plug body 4
And insert the plug body 4 from above. Next, the plug body 4 and the plug body attaching / detaching device 5 are hoisted together by an overhead crane (not shown) and conveyed to above the reactor pressure vessel 1. Next, it is gradually lowered into the furnace, and when the axis of the plug body 4 coincides with the axis of the main steam nozzle 2, the lowering operation is stopped. This is the state shown in FIG. Next, the compressed water is supplied equally to the four hydraulic pistons 27 and the plunger is
28 is projected, and the plug body 4 is advanced together with the carriage 29 toward the main steam nozzle 2. Then, when the seal ring 10 of the plug body 4 comes into contact with the inlet of the main steam nozzle 2, the supply of compressed water is stopped and the inserting operation of the plug body 4 is completed.

Next, the drive operation of the lock plug 6 of the plug body 4 is started. First, the driving fluid is supplied to the driving cylinder 5 through the pipe 8a. As a result, the lock plug 6 slides in the X direction in FIG. By sliding the lock plug 6 in the X direction, the four wedge bodies 7 move in the Y direction in FIG. 1 and are brought into close contact with the inner surface of the main steam nozzle 2. This is the state shown in FIG. This completes the insertion and fixing of the plug body 4 to the main steam nozzle 2, and the removal work of the plug body attaching / detaching device 5 is started. Since the plug body 4 is located outside the tip of the beam 24, if the plug body attaching / detaching device 5 is lifted upward by the crane device, the spectacle member 31 is detached from the bracket 30, so that the plug body attaching / detaching device 5 is Separate from the plug body 4. The detached plug body attaching / detaching device 5 is lowered and stored on the floor. In this way, the plug body attaching / detaching device 5
FIG. 5 shows a state in which is removed. Incidentally, in FIG. 5, two wedge bodies 7 which have not appeared in FIG. 4 also appear.

This completes the mounting of the plug body 4 on the main steam nozzle 2,
The plug body 4 thus mounted is kept watertight and airtight with respect to water pressure from the inside of the reactor pressure vessel 1 and fluid pressure from the main steam pipe 3 side. This will be described in detail. First, when pressure acts from the inside of the reactor pressure vessel 1, the flange 9 causes the main steam nozzle 2
Is pushed toward the inlet side of the main steam pipe 3 of the plug body 4.
It is possible to prevent the water from leaking to the side, and since the seal structure is formed by the seal rings 10 and 12, it is possible to reliably prevent the reactor water from leaking from the reactor pressure vessel 1 side to the main steam pipe 3 side. be able to.

Next, a case where a fluid pressure is applied from the main steam piping 3 side to the reactor pressure vessel 1 side (a back pressure acts) for the purpose of, for example, a leak test of the main steam piping 3 will be described. In this case, since the four wedge bodies 7 are urged in the radial direction by the lock plug 6 and pressed against the inner surface of the main steam nozzle 2, the plug body 4 moves from the main steam nozzle 2 to the reactor pressure vessel. 1
There is no way out. And the seal ring 10 and
Since the seal structure is maintained by 12, the fluid does not leak from the main steam pipe 3 side to the reactor pressure vessel 1 side.

As described above, according to the present embodiment, not only the pressure from the reactor pressure vessel 1 side but also the back pressure from the main steam pipe 3 side does not require the back pressure support ring as in the conventional case. It is possible to reliably maintain the closed state of the main steam nozzle 2. Therefore, the workability of the maintenance / inspection work of the main steam isolation valve is improved, and even when a back pressure is applied for the leakage test, it is possible to pressurize with confidence. Since it is not necessary to install a back pressure support ring in the reactor pressure vessel 1 as described above, not only the maintenance and inspection work of the main steam isolation valve but also other works such as nuclear refueling work or jet work It becomes possible to smoothly carry out inspection work and the like during the period of use of the pump and the like.

Next, a second embodiment will be described with reference to FIGS. 6 and 7. On the outer periphery of the plug body 4 of this embodiment, an annular recess 41 which is elongated in the axial direction is formed, and a hollow elastic body 42 is mounted in this annular recess 41. A pipe 43 is connected to the hollow elastic body 42, and a fluid can be appropriately injected into the hollow elastic body 41. On the other hand, the piston rod 5b connecting the lock plug 6 and the drive piston 5a receives the pressure of the fluid flowing into the plug body 4 from the through hole 6a provided at the tip end side of the plug body 4 so as to move the piston rod 5b. A backup piston 45 for urging toward the reactor pressure vessel is integrally formed. A seal ring 46, which slidably contacts the inner peripheral surface of the plug body 4, is attached to the outer periphery of the backup piston 45. A fluid discharge hole 47 is formed at the rear end of the plug body 4 to allow the backup piston 45 to move forward and backward. The other structure is similar to that of the first embodiment, and the description thereof is omitted.

The plug body 4 having the above structure is attached and detached by the plug body attaching / detaching device 5 as in the case of the first embodiment. However, when the plug body 4 is attached, no fluid is supplied to the hollow elastic body 42. The state is as shown in FIG. Then, after being attached to the main steam nozzle 2, a fluid is supplied into the hollow elastic body 42 through the pipe 43 to expand the fluid to a state as shown in FIG. 7, thereby maintaining watertightness and airtightness. .
Of course, to maintain this watertightness and airtightness, the seal ring 10
Also contributes.

When the plug body 4 functions with respect to the fluid pressure from the main steam pipe 3 side, if the drive pressure supplied to the drive cylinder 5 is lost due to an accident,
It is expected that the urging of the wedge body 7 by the lock plug 6 in the radial direction is lost and the closed state of the main steam nozzle 2 is impaired. However, in the case of the present embodiment, the fluid pressure on the main steam pipe 3 side acts on the piston 45 through the through hole 6a of the lock plug 6, and the piston 45 is made to move through the piston 45.
Since it is biased to the side, the lock plug 6 is still X in the figure.
The wedges 7 are continuously urged in the radial direction by the lock plugs 6. Therefore, the plug body 4 does not escape from the main steam nozzle 2 to the reactor pressure vessel 1 side, and the closed state of the main steam nozzle 2 can be reliably maintained even in the event of an accident as described above.

As described above, according to the second embodiment, the hollow elastic body 41 is used first, and when the plug body 4 is mounted, no fluid is supplied into the hollow elastic body 41, so that mounting is extremely easy. Is. Further, even if an abnormality occurs in the drive cylinder 5 when the fluid pressure is received from the main steam pipe 3 side, the wedge plug 7 can be maintained in the radially expanded state by the lock plug 6, Therefore, the main steam nozzle 2 with the plug body 4
The closed state can be reliably maintained.

[Effects of the Invention] As described in detail above, according to the present invention, the main steam of a reactor pressure vessel can reliably prevent the plug body from coming out of the main steam nozzle without using a support ring or the like. A nozzle closing device can be provided.

[Brief description of drawings]

1 to 5 are views showing a first embodiment of the present invention.
FIG. 1 is a cross-sectional view showing the structure of a main steam nozzle closing device, FIG. 2 is a cross-sectional view of the main steam nozzle closing device showing a state in which a wedge is pressed against the inner peripheral surface of the main steam nozzle, and FIG. The figure which shows the structure of a plug body attaching / detaching device, FIG. 4 is a figure which shows the attachment of the plug body by a plug body attaching / detaching device, FIG. 5 is the figure which shows the state which attached the plug body by the plug body attaching / detaching device, FIG. FIG. 7 is a view showing a second embodiment, FIG. 6 is a sectional view showing the constitution of the main steam nozzle closing device, FIG. 7 is a sectional view of the main steam nozzle closing device for explaining the action, FIG. 8 is a view showing a state in which a conventional main steam closing device is attached to a main steam nozzle. 1 ... Reactor pressure vessel, 2 ... Main steam nozzle, 2a ... Tapered part, 3 ... Main steam pipe, 4 ... Plug body, 5 ... Drive cylinder, 6 ... Lock plug, 7 ... Wedge Body, 9 ...
Flange, 10,12 …… Seal ring.

Claims (1)

[Claims] 1. A drive having a hollow cylindrical plug body to be inserted into a main steam nozzle of a reactor pressure vessel from the reactor pressure vessel side, and a piston rod provided in the plug body and protruding from a tip of the plug body. A cylinder, a drive fluid supply pipe and a withdrawal pipe for supplying a drive fluid to the drive cylinder to move the piston rod forward and backward, a lock plug having a wedge-shaped cross section provided at a tip of the piston rod, and a side surface of the lock plug. A wedge body that has an engagement surface that engages with the main steam nozzle by the backward movement of the piston rod, and a plug body that is provided at the rear end of the plug body and that enters the main steam nozzle. A flange for preventing, and a seal member provided on the outer periphery of the plug body,
And a backup piston for urging the piston rod toward the reactor pressure side in response to the pressure of the fluid flowing into the plug body from a through hole provided in the plug body and provided on the tip side of the plug body. A main steam nozzle closing device for a reactor pressure vessel characterized by the above.