JPH01143998A - Closing device for main steam nozzle of reactor pressure vessel - Google Patents

Abstract

PURPOSE:To improve the accuracy of registration and fine adjustment of plug units, and main steam nozzles by providing a backup ring, the plug units, plug attaching/detaching mechanisms, self-aligning mechanisms and turning mecha nisms. CONSTITUTION:The backup ring 21 is concentrically inserted into a reactor pressure vessel 2. The plug units 22 are mounted to the positions opposite to the main nozzles 3 of the ring 21 and are attachably and detachably inserted into the nozzles 3. The plug attaching/detaching mechanisms 23 move the units 22 along the radial direction of the ring 21. The self-aligning mechanisms 24 are interposed between the ring 21 and the vessel 2 and press the ring 21 toward the radial direction at plural points in the circumferential direction of the ring. The turning mechanisms 25 turn the ring 21 relative to the vessel 2. The ring 21 is adjusted to the position concentrical with the vessel 2 and is held in said position according to this constitution. The positional relation of the units 22 and the nozzles 3 is adjusted with high accuracy by adjusting the relative positional relation of the ring 21 and the vessel 2 in the circumferential direction thereof.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for sealing a main steam nozzle formed in a reactor pressure vessel from the inside of the reactor pressure vessel during nuclear fuel replacement work in a nuclear reactor. The present invention relates to a closure device used in this case.

[Prior Art] In general, nuclear fuel exchange work, main steam line inspection work, or disassembly inspection work, leakage inspection work, etc. of the main steam isolation valve installed in the middle of the main steam line are carried out at nuclear facilities. In such cases, the main steam nozzle that connects the reactor pressure vessel and the main steam line is sealed from the inside of the reactor pressure vessel (7) to isolate the reactor pressure vessel and the main steam line. ing.

As a closure device used to seal the main steam nozzle as described above, for example, a structure shown in FIGS. 12 and 13 is being considered.

The main steam nozzle closing device l shown in this example is designed to simultaneously seal four main steam nozzles 3 formed on the same horizontal level on the peripheral wall of the reactor pressure vessel 2. Four plug units 4 are inserted into the steam nozzle 3 from the inside of the reactor pressure vessel 2, and the main steam nozzle is held horizontally by a bracket 5 disposed on the inner circumference of the reactor pressure vessel 2. The plug unit 3 is provided with a backup ring 6 that supports the back of the plug unit 4 inserted into the plug unit 3 and prevents the plug unit 4 from coming off.

Moreover, the main steam nozzle 3 is attached to the backup ring 6.
An X-shaped beam 7 intersecting at the same angle as the separation angle is removably attached to each end of the beam 7, and a plug attachment/detachment mechanism such as a hydraulic cylinder that can be engaged with and detached from the plug unit 4 is attached to each tip of the beam 7. 8 are arranged.

Furthermore, in order to reduce the weight, the backup ring 6 is formed into a box-shaped tube shape in which both side edges of an upper plate 9 and a lower plate 10 are connected by a side plate II, as shown in FIG. 9 and the lower plate IO, a plurality of holes 12 are formed so as to penetrate vertically.

The closure device 1 configured as described above is used to supply seal water to prevent the diffusion of radioactive materials into the reactor pressure vessel 2 and the actuator well 13 above it during nuclear fuel exchange work, etc., as shown in FIG. W is applied and this seal is used in the water world.

That is, in the operation room 14 above the reactor well 13, the closure device 1 is suspended by a crane or the like hooked to the beam 7, and then lowered into the reactor pressure vessel 2, and the plug unit 4 is connected to the main steam nozzle 3. The descent is stopped when the plug unit 4 is opposed to the main steam nozzle 3, and then the plug unit 4 is inserted into the main steam nozzle 3 using the plug attachment/detachment mechanism 8 to seal the main steam nozzle 3. is slightly raised and placed on the bracket 5, and the backup ring 6 is brought into contact with the inner end surface of each plug unit 4 to prevent the plug unit 4 from being removed. Remove beam 7 from backup ring 6 and access the control room! 4, the inside of the backup ring 6 is wide open.

[Problems to be Solved by the Invention] The present invention attempts to solve the following problems in the conventional technology described above.

That is, in the technique described above, the plug unit 4
When inserting the plug unit into the main steam nozzle 3, the work must be done with the backup ring 6 and beam 7 suspended, which makes the device unstable and makes it difficult to align the plug unit 4 and the main steam nozzle 3. The problem is that fine adjustment is difficult, impairing the smoothness of the work, and since the work is performed in a sealed water environment, the above-mentioned problems tend to be exacerbated.

[Means for Solving the Problems] An object of the present invention is to provide a closure device for a main steam nozzle of a nuclear reactor pressure vessel that can effectively solve the problems in the conventional technology described above. In order to achieve
The main steam nozzle closing device according to the present invention particularly includes a backup ring that is inserted concentrically into the inside of a reactor pressure vessel, and a backup ring that is installed at a position facing the main steam nozzle to close the main steam nozzle. a plug unit that is removably inserted into the backup ring; a plug attachment/detachment mechanism that moves the plug unit along the radial direction of the backup ring; The reactor pressure vessel is characterized by comprising an alignment mechanism that presses the backup ring radially inward at a plurality of locations in the circumferential direction thereof, and a rotation mechanism that rotates the backup ring relative to the reactor pressure vessel.

[Function] When the main steam nozzle closure device for a reactor pressure vessel according to the present invention is inserted into the reactor pressure vessel from above, the alignment mechanism between the backup ring and the reactor pressure vessel causes Pressing the backup ring from the outside in the circumferential direction at a plurality of locations in the circumferential direction toward the center of the reactor pressure vessel to automatically adjust the position so that it is concentric with the reactor pressure vessel, and to adjust the adjusted position. hold in
In addition, the rotation mechanism rotates the backup ring relative to the reactor pressure vessel in the circumferential direction to adjust the relative positional relationship between the backup ring and the reactor pressure vessel in the circumferential direction. , the positional relationship between the backup ring and the reactor pressure vessel, that is, the positional relationship between the plug unit and the main steam nozzle, is adjusted with high precision.

[Example] Hereinafter, an example of the present invention will be described based on FIGS. 1 to 1+.

In the following description, the same reference numerals are used for parts common to those in FIGS. 12 to H to simplify the description.

In FIG. 1, reference numeral 20 indicates a main steam nozzle closing device 20 according to the present embodiment, which connects the main steam nozzles 3 formed at four locations in the reactor pressure vessel 2 to the reactor pressure vessel 2 as in the conventional case. A backup ring 21 that is inserted concentrically into the inside of the reactor pressure vessel 2, and a position of this backup ring 21 facing the main steam nozzle 3. a plug unit 22 that is attached to the main steam nozzle 3 and removably inserted into the main steam nozzle 3; a plug attachment/detachment mechanism 23 that moves the plug unit 22 along the radial direction of the backup ring 21; an alignment mechanism 24 that is interposed between the pressure vessel 2 and the backup ring 21 and press the backup ring 21 radially inward at a plurality of locations in the circumferential direction; Rotating mechanism 25 that rotates relative to the
The general configuration includes:

Next, the details will be described. The backup ring 21 has a rectangular cross section and a hollow interior.

Further, inside this backup ring 21, a backup jack 26 is provided at the same pitch as the pitch of the main steam nozzle 3, and this backup jack 26 is connected to the backup ring 21 as shown in FIG. 2
A backup wand 2 is provided to be slidable along the radial direction of I and protrude toward the outside of the backup ring 21, and this backup rod 27
are integrally attached and are slidably mounted in the backup ring 21 along the radial direction thereof, and a movable plate 28 on the side opposite to the side on which the backup rod 27 is attached. An air jack 29 is interposed between the surface of the movable plate 21 and the inner surface of the backup ring 21, and an air jack 29 is interposed between the surface of the movable plate 21 on which the backup rod 27 is attached and the inner surface of the backup ring 21. It is constituted by a return spring 30 that springs the plate 23 in a direction in which the backup rod 27 is housed in the backup ring 21.

Furthermore, a beam 31 intersecting in an X-shape at the same angle as the included angle of the main steam nozzle 3 is removably attached to the upper part of the backup ring 21, and the beam 31 is connected to the backup ring 2I. As shown in FIGS. 2 and 4, the lower part of the part to be placed is provided with a locking/unlocking mechanism 32 that is connected to and disconnected from the backup ring 21 from its inner peripheral surface side, and the upper part is A plug guide mechanism 33 that holds the plug unit 22 and controls its moving direction, and the plug attaching/detaching mechanism 23 are provided, and the beam 3! is the plug guide mechanism 3
The backup ring 2 is moved so that the center line of the plug unit 22 held by the plug unit 3 is deviated from the center line of the backup rod 27 by a predetermined distance L2 in the circumferential direction.
It is attached to 1.

On the outer peripheral surface of the backup ring 21, locking members 34 are integrally provided at a plurality of locations spaced apart in the circumferential direction (in this embodiment, at four locations as shown in FIG. 1). This locking member 34 includes two engaging surfaces 34a and 34b that are engaged from above with a plurality of brackets 5 protruding from the inner surface of the reactor pressure vessel 2. 34b, as shown in FIG. 2, are spaced apart by a predetermined distance in the length direction of the reactor pressure vessel 2, and also in the circumferential direction by a predetermined distance L! They are separated by a minute.

As shown in FIGS. 3 and 4, the plug unit 22 includes a small diameter portion 22a that has an outer diameter that is approximately the same as the inner diameter of the main steam nozzle 3 and is inserted into the main steam nozzle 3, and this small diameter portion 22a.
a flange portion 22b that is connected to the end portion located inside the reactor pressure vessel 2 of a and has an outer diameter larger than the inner diameter of the main steam nozzle 3; A hydraulic sealing mechanism 35 and a pneumatic sealing mechanism 36 are sequentially sealed from one end to the other end, and further,
An O-shaped puffer 3 is provided at the boundary between the small diameter portion 22a and the flange portion Hb.

As shown in FIGS. 1 and 3, the plug attachment/detachment mechanism 23 includes a pneumatic cylinder 38 disposed along the length of the beam 31, and a distal end of a movable rod 38a of the pneumatic cylinder 38. The hand 40 is provided with a hook 3g that is attached to and detached from the center of the flange portion 22b of the plug unit 22, and this hook 39
is solenoid 4! By being rotated by
The plug unit 22 can be connected to and removed from the plug unit 22.

As shown in FIG. 1, the alignment mechanisms 24 are provided at six locations on the outer peripheral surface of the backup ring 21 at predetermined intervals in the circumferential direction. As shown in FIG. 6, a bracket 42 is integrally attached to the backup ring 21, and a swing arm is attached to the bracket 42 so as to be swingable in a plane passing through the center line of the reactor pressure vessel 2. 43, a press rod 44 which is slidably attached to the swing end of the swing arm 43 and is brought into contact with the outer circumferential surface of the backup ring 21, and a press rod 44 which is always directed toward the backup ring 21. Coil spring 4 that springs
S and the pressing rod 44 at the swinging end of the swinging arm 43.
A rolling element 46 is provided on the opposite side to the side where the closure device 20 is provided, and is brought into contact with the inner surface of the reactor pressure vessel 2 when the closure device 20 is inserted into the reactor pressure vessel 2.

The diameter of the circle obtained by connecting the rolling elements 46 of the swinging arms 43 of each alignment mechanism 24 before insertion into the reactor pressure vessel 2 is made larger than the inner diameter of the reactor pressure vessel 2. It is set.

In this embodiment, as shown in FIG. 1, the turning mechanisms 25 are provided at two points symmetrical about the center point of the beam 31, as shown in FIG. As shown in FIG. 8, a base plate 47 is integrally attached to the beam 31, and a guide groove 48a is integrally attached to the base plate 47 and extends in the radial direction of the backup ring 21. A member 48 and a sliding body 49 slidably fitted into the guide groove 8a.
A driving roller 5G is attached to the sliding body 49 so as to be rotatable about an axis parallel to the center line of the backup ring 2I, and a driving roller 5G is attached to the inside of the sliding body 49 to rotationally drive the driving roller 5G. A motor 51 that connects the motor 5I and the drive roller 50, a gear box 52 that is connected to the sliding body 49 and reciprocates the sliding body 49 along the guide groove 48a, and a gear box 52 that connects the motor 5I and the drive roller 50. A pneumatic cylinder 53 that brings 50 into contact with or separates from the inner surface of the reactor pressure vessel 2
It is composed of.

As shown in FIG. 4, the engagement/disengagement mechanism 32 includes an engagement rod 55 that is fitted into an engagement recess 54 formed on the inner circumferential surface of the backup ring 21, and a length of the engagement rod 55. The pneumatic cylinder 56 is inserted into and removed from the engagement recess 54 by sliding in the direction.

The plug guide mechanism 33, as shown in FIG.
The fixed guide 57 supports the outer periphery of the guide 57, and the movable guide S8 supports the small diameter portion 22a. The movable guide 58 has a lifting rod 59 at its lower part.
is integrally attached, and between the lifting rod 59 and the beam 31, the movable guide 58 together with the lifting rod 59 can be moved to an upper position supporting the plug unit 22 and to be spaced apart from the plug unit 22. Air jack 6 for reciprocating between two positions with the lower position
0 is inserted. The movable guide 58 is
When the tip of the plug unit 22 is inserted into the main steam nozzle 3, it is lowered to allow passage of the seven ring portion Hb.

Furthermore, in this embodiment, the backup jack 26
, engagement/disengagement mechanism 32, hand 40. and movable guide 58
In order to detect the operating state of the
are provided for each.

Further, in the center of the beam 31, there is a level 63 for detecting the horizontality of the closure device 20, a TV camera 64 for detecting the rotation angle, and a TV camera for detecting the operating state of each plug attachment/detachment mechanism 23, etc. A monitoring unit 67 with 65 and 66 is installed.

The TV camera 64 for detecting the rotation angle is attached to a reference needle 68 provided on the inner surface of the reactor pressure vessel 2 and on the backup ring 21 near the reference needle 68, and is mounted on the backup ring 21 in the circumferential direction. The rotation angle of the backup ring 21 is detected by cooperation with an aiming plate 69 equipped with a scale along the axis, and this monitoring unit 67
The signals are sent to a central computer (not shown) installed in the control room 14 and used to control each actuating member of the closure device 20.

Next, the closure device 20 of this embodiment configured as described above
The effect of this will be explained as follows.

"Equipment assembly and operation confirmation work" In the operation room 14 above the reactor pressure vessel 2, the backup ring 21. Beam 31. Assemble the plug unit 22, piping, etc., and check their operation.

“Hoisting and lowering work” The beam 31 is suspended by a crane or the like and immersed in the seal water inside the reactor pressure vessel 2.

With such an insertion operation into the reactor pressure vessel 2, the rolling elements 46 attached to the swing arms 43 of each alignment mechanism 24 come into contact with the inner surface of the reactor pressure vessel 2, thereby causing the above-mentioned The swing arm 43 swings toward the backup ring 21 while compressing the coil spring 45, and as a result, the coil spring 45 of each alignment mechanism 24
Due to the balance of the elastic forces, the closure device 20 is automatically positioned at the center of the reactor pressure vessel 2.

The closing device 2G is lowered further from this point, and when the bracket 5 attached to the inner surface of the reactor pressure vessel 2 overlaps approximately the middle part of the locking member 34 of the backup ring 21 in the circumferential direction, the lowering is stopped. Stop.

After stopping the descent, the pneumatic cylinder 53 of the turning mechanism 25 is actuated to bring the drive roller 50 into contact with the inner surface of the reactor pressure vessel 2, and the drive roller 5G is rotated to close the closure device. 20 in the circumferential direction to bring the bracket 5 into contact with the locking member 34 from the circumferential direction.

Next, after separating the driving roller 50 from the inner surface of the reactor pressure vessel 2, the closing device 20 is further lowered to close the engagement surface 3 formed above the locking member 34.
4a is engaged with the bracket 5 from above, as shown in FIGS. 3 and 4.

In this state, the plug unit 22 held by the plug guide mechanism 33 is positioned coaxially with the main steam nozzle 3.

"Plug unit insertion work" The pneumatic cylinder 38 of the plug attachment/detachment mechanism 23 is operated to push out the plug unit 22 toward the main steam nozzle 3.
When the tip of the plug unit 22 is fitted into the main steam nozzle 3, the movable guide 58 constituting the plug guide mechanism 33 is lowered to the lowest position. After lowering the movable guide 58 in this way, the pneumatic cylinder 38 is further actuated to move the plug unit 22.
Push it in until the O-ring 37 abuts against the inner end of the main steam nozzle 3, as shown in FIG.

After the grip of the plug unit 22 by the hand 40 is released, the hand 40 is returned to its original position.

"Fixing the Backup Ring" The beam 31 is lifted by a distance L2 in the vertical direction between the upper and lower engaging surfaces 34a and 34b formed on the locking member 34, and in this lifted state, the turning mechanism 2S is operated again to fix the beam 31. The driving roller 5G is brought into contact with the inner surface of the reactor pressure vessel 2, and the closing device 20 is rotated in the circumferential direction by the distance of 8 minutes by the driving roller 50, so that the lower part formed on the locking member 34 is closed. The locking surface 34b is positioned above the bracket 5, and then the closure device 20 is lowered slightly to engage the lower locking surface 34b onto the bracket 5 from above.

In this state, as shown in FIG.
No. 6 backup rods 27 are located coaxially with the plug unit 22.

From this, by operating each air jack 29 and pressing the backup rod 27 against the plug unit z2, these backup jacks 26 and the backup ring 2! The four plug units 22 are rigidly connected through the plug units 22 .

Therefore, even when an external force that pushes the plug units 22 back into the reactor pressure vessel 2 is applied, these plug units 22 will not fall out.

Furthermore, in parallel with the fixing operation of the backup ring 2I, the hydraulic sealing mechanism 3 of the plug unit 2z is
5 and the pneumatic sealing mechanism 36, the plug unit 2! and the inner surface of the main steam nozzle 3. The O-ring 37 is brought into close contact with the inner surface of the reactor pressure vessel 2 and the seventh rung portion Hb of the plug unit 22 by the sealing action of both seal mechanisms 35 and 36 and the pressing action of the backup jack 26. Due to the synergistic effect, each main steam nozzle 3 is reliably sealed.

“Handling beam removal work” Operate the pneumatic cylinder 56 of the engagement/disengagement mechanism 32 to move the engagement rod 55 to the backup ring 2! By pulling up the beam 31 after separating it from the plug unit 22 and the backup ring 21, as shown in FIG.
remains in the reactor pressure vessel 2, and the inside of this backup ring 21 is wide open to remove obstacles such as nuclear fuel exchange work.

After creating the state shown in FIG. 11, for example, about 1
For several months, nuclear fuel replacement work, disassembly and assembly of the main steam isolation valve, leak tests, etc. are carried out, but as mentioned above, the main steam nozzle 3 is reliably sealed by the plug unit 22 and the plug unit 22 is prevented from being removed. Because of this, the above-mentioned work is carried out with great precision.

When performing such operations, backup ring 2
1 uses the reactor pressure vessel 2 as a support and is operated with the reactor pressure vessel 2 in constant contact with the reactor pressure vessel 2.
Shaking and the like of the closure device 20 are significantly reduced, and reliable operation is performed even though it is remote controlled, and as a result,
The plug unit 22 and the main steam nozzle 3 are aligned with high precision, and the insertion operation of the plug unit 22 is simplified.

On the other hand, when removing the blocking device 20 after the completion of nuclear fuel exchange work, etc., after reattaching the beam 31 to the backup ring 2I, from inside the reactor pressure vessel 2 to the operating room by reattaching the beam 31 to the backup ring 2I, Pull it up to your eyes.

It should be noted that the shapes and dimensions of each component shown in the above embodiments are merely examples, and can be changed in various ways based on design requirements and the like.

[Effects of the Invention] As explained above, the main steam nozzle blocking device for a reactor pressure vessel according to the present invention closes the main steam nozzle formed in the reactor pressure vessel from the inside of the reactor pressure vessel. A main steam nozzle closure device configured to seal the main steam nozzle includes a backup ring inserted concentrically into the reactor pressure vessel, and a backup ring mounted at a position facing the main steam nozzle to prevent the main steam nozzle from being closed. a plug unit that is detachably inserted into the nozzle; a plug attachment/detachment mechanism that moves the plug unit along the radial direction of the backup ring; and a plug unit that is interposed between the backup ring and the reactor pressure vessel, and It is characterized by comprising an alignment mechanism that presses the ring radially inward at a plurality of locations in the circumferential direction, and a rotation mechanism that rotates the backup ring relative to the reactor pressure vessel. It has the following excellent effects:

(2) Due to the action of the alignment mechanism, the closing device can be automatically positioned at the center of the reactor pressure vessel simply by inserting the closing device into the reactor pressure vessel.

(2) Positioning of the closure device in the circumferential direction is forcibly performed by a rotating device, allowing quick and highly accurate positioning even when working underwater.

■When moving the closure device, the device can be kept in constant contact with the reactor pressure vessel and can be moved using the reactor pressure vessel as a support, which greatly suppresses shaking during movement and improves performance from this point of view. Enables precise positioning operations.

(2) Due to the synergistic effects of (1) to (2) above, the accuracy of inserting the plug unit into the main steam nozzle can be greatly improved, and the operation thereof can be simplified.

[Brief explanation of the drawing]

Figures 1 to 11 show one embodiment of the present invention, with Figure 1 being a plan view, Figure 2 being a partially sectional front view of the main parts, and Figure 3 showing details of the backup jack. FIG. 4 is a vertical cross-sectional side view showing details of the engagement and disengagement mechanism.
Figure 5 is a front view of the centering mechanism, Figure 6 is a vertical cross-sectional side view of the centering mechanism, Figure 7 is a vertical cross-sectional side view of the turning mechanism, Figure 8 is a front view of the turning mechanism, and Figure 9. Figures 11 to 11 are longitudinal sectional side views for explaining the operation, Figures 12 to H show examples of conventional closure devices, Figure 12 is a plan view of the entire device, and Figure 13 is a backup diagram. FIG. 14 is a longitudinal cross-sectional view of the ring, and is a vertical cross-sectional side view showing the ring inserted into a reactor pressure vessel for explaining the outline of the method of use. 2... Reactor pressure vessel, 3... Main steam nozzle, 5... Bracket, 20...
Closure device, 21...Backup ring, 22
...Plug unit, 23...Plug attachment/detaching mechanism, 24...Aligning mechanism, 25...
・Swivel mechanism, 26...Backup jack,
31... Beam, 32... Engagement/disengagement mechanism,
33...Plug guide mechanism, 34...
Locking member, 42...Bracket, 43...
... Swinging arm, 44 ... Pressing rod, 45.
... Coil spring, 46 ... Rolling element, 47 ... Board, 48 ... Guide member, 48a ... Guide groove, 49 ... ...Sliding body, 50 ... Drive roller, 51 ... Motor, 52 ... Gear box, 53 ...
・Pneumatic cylinder. Figure 3 Figure 4 Two river maps

Claims (1)

[Claims] In a main steam nozzle closure device that seals a main steam nozzle formed in a reactor pressure vessel from the inside of the reactor pressure vessel, a backup that is inserted concentrically into the inside of the reactor pressure vessel. ring, a plug unit that is attached to the backup ring at a position facing the main steam nozzle and is removably inserted into the main steam nozzle, and a plug unit that moves the plug unit along the radial direction of the backup ring. an alignment mechanism that is interposed between the backup ring and the reactor pressure vessel and presses the backup ring radially inward at multiple points in the circumferential direction; 1. A closure device for a main steam nozzle of a reactor pressure vessel, comprising a rotation mechanism for rotating relative to the reactor pressure vessel.