JPH0531958B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an internal pump handling device for an internal pump type improved boiling water nuclear reactor (A-BWR).

[Technical Background of the Invention] A conventional example will be described with reference to FIGS. 1 and 2. FIG. 1 is a vertical cross-sectional view showing a schematic configuration of a boiling water reactor (hereinafter referred to as BWR). In the figure, reference numeral 1 denotes a reactor pressure vessel, in which a reactor core 2 and a coolant 3 are housed. The reactor core 2 is composed of a plurality of fuel assemblies (not shown). A steam separator 4 is installed above the core 2, and a steam dryer 5 is installed above the steam separator 4. That is, the coolant 3 flows through the reactor core 2 from below to above, and at this time its temperature increases due to the heat of nuclear reaction in the reactor core 2, resulting in a two-phase flow state of water and steam. The coolant 3 in a two-phase flow state flows into the steam-water separator 4 and is separated into water and steam. The separated steam is dried in the steam dryer 5 and turned into dry steam, which is transferred to the main steam pipe 6 connected to the upper part of the reactor pressure vessel 1.
It is supplied to a turbine system (not shown) through the system and used for work. On the other hand, water flows downward through the downcomer portion 7 on the outer periphery of the core 2, and flows through the core 2 again from the bottom to the top. The same cycle is repeated thereafter.

A recirculation system 8 is connected to the reactor pressure vessel 1 . This recirculation system 8 is connected to the reactor pressure vessel 1
It consists of a recirculation pump 9 installed outside, a jet pump 10 installed inside the reactor pressure vessel 1, and a recirculation pipe 11 connecting these recirculation pumps 9 and jet pumps 10.
This recirculation system 8 is configured to forcefully circulate the coolant 3 within the reactor core 2 . In the figure, reference numeral 12 indicates a control rod, and reference numeral 13 indicates a control rod drive mechanism for inserting or withdrawing the control rod 12 into the reactor core 2.

In a BWR with such a configuration, the recirculation pump 9
A recirculation pipe 11 and a recirculation pipe 11 are installed outside the reactor pressure vessel 1, and thus the recirculation pipe 11 forms a boundary for the coolant 3. Therefore, if the recirculation pipe 11 were to break, a loss of coolant accident would occur, which could lead to secondary disasters. Therefore, an emergency core cooling system has been installed in anticipation of such an accident, but the number of piping and attached equipment has increased, making the configuration complex and the equipment larger. Therefore, instead of such an external circulation type BWR, an internal pump type A-BWR is being considered in which a pump is built into the reactor pressure vessel 1 and the coolant 3 is directly circulated.

The configuration of this A-BWR will be explained below.
FIG. 2 is a vertical cross-sectional view showing a schematic configuration of the A-BWR. Note that the same parts as in the configuration of the external circulation BWR described above are designated by the same reference numerals, and their explanations are omitted. An internal pump 21 is installed below the downcomer part 7 in the lower mirror 1A of the reactor pressure vessel 1.
A plurality of units are installed at equal intervals in the circumferential direction, passing through the area. This internal pump 21 has a configuration as shown in FIG. That is, the internal pump 21 includes a pump section 22 and a motor section 2.
It is composed of 3. The pump section 22 is
It is composed of an impeller 24, a differential user 25, a differential user wear ring 26, and the like. The impeller 24 is connected to the motor section 23 via a drive shaft 27. The diff user 25 is fixed to the upper part of the nozzle 1B protruding from the bottom of the reactor pressure vessel 1 via a stretch tube 28.
8 is fixed by a stretch tube nut 29. This stretch tube nut 2
A secondary seal ring (hereinafter abbreviated as secondary seal) 30 is attached below 9.

The motor section 23 is composed of a rotor 31, a stator 32, etc., and its tip is inserted into the nozzle 1B, and is housed in a casing 33 welded to the lower mirror 1A of the reactor pressure vessel 1. There is. Note that reference numeral 34 in the figure indicates a cooling water circulation pipe, and cooling water is circulated within the motor section 23 through this cooling water circulation pipe 34 to prevent the motor section 23 from burning out.

The A-BWR with this configuration does not require recirculation piping because it does not have a recirculation pump installed outside the reactor pressure vessel 1, unlike the external recirculation type BWR described above, and therefore does not require recirculation piping. The space within the recirculation equipment can be significantly reduced. Furthermore, since the assumed fracture area is reduced by the amount of the recirculation pump and recirculation piping, the capacity of the emergency core cooling equipment can be reduced. Furthermore, since the motor section 23 is housed in a casing 33 with excellent watertightness, there is no need for a sliding shaft sealing device (grand section), and the risk of core leakage is therefore small.

[Problems with Background Art] Maintenance and inspection work for the internal pump in the above configuration is performed as follows. First, the secondary seal 30 seals between the casing 33 and the drive shaft 27 to shut off water in the reactor pressure vessel 1, and then the water in the casing 33 is drained. Thereafter, the motor section 23 is removed from below the casing 33. Next, after a closing flange is attached to the lower end of the casing 33, makeup water is filled into the casing 33, and then the secondary seal 30 is released. In this state, the impeller 24 and the drive shaft 27 are removed from above the reactor pressure vessel 1. Next, the opening of the diffuser 25 is closed from above the reactor pressure vessel 1 with an upper closing plate, and the water in the casing 33 is discharged. In this state, remove the closing flange from below the casing 33, and remove the secondary seal 30 and stretch tube nut 29 from inside the casing 33. After attaching the closing flange to the lower end of the casing 33 again, make-up water is filled. In this state, from above the reactor pressure vessel 1, the upper closing plate, the differential user 2
5. Remove the differential user wear ring 26 and stretch tube 28. For installation after inspection and maintenance, perform the above procedure in reverse order.

All of this work is done remotely, but the location where the internal pump 21 is installed is extremely narrow, so the work is expected to be difficult. In particular, the secondary seal 30 is smaller than other parts, making it difficult to attach and detach it. As a result, maintenance and inspection work would take a long time, potentially reducing the reactor's operating rate.

[Object of the Invention] The present invention has been made based on the above-mentioned points, and its purpose is to facilitate the installation and removal work of the secondary seal, shorten the time required for maintenance and inspection work of the internal pump, Another object of the present invention is to provide an internal pump handling device that can improve the operating rate of a plant.

[Summary of the Invention] That is, the internal pump handling device according to the present invention includes a base that is movable up and down below a casing in which a motor section of an internal pump is housed, and a base that is installed at the center of the upper surface of the base and a support body inserted into a casing; a secondary seal handling tool having a claw member that is movable up and down on the top of the support body and can be opened and closed for attaching and detaching a secondary seal ring of the internal pump; a secondary seal handling tool elevating means for moving the secondary seal handling tool upward to make the claw member protrude from the center hole of the secondary seal ring; A claw member driving means for engaging the upper surface of the secondary seal ring, a wedge provided below the claw member, and a washer attached to the lower surface of the secondary seal ring by moving the wedge upward. The structure further includes wedge driving means for pushing and bending a groove portion formed on the lower surface of the seal ring to release the engagement between the washer and the engagement groove formed on the inner circumferential surface of the casing.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 4 and 5. It should be noted that the same parts as in the prior art are denoted by the same reference numerals and their explanations are omitted. FIG. 4 is a detailed view of section A in FIG. 3. Said secondary seal 3
0 is attached to an engagement groove 51 formed in the inner wall 33A of the casing 33 and supported from below by a washer 52. Further, this washer 52 is fixed to the secondary seal 30 with a socket bolt 53.

Next, a handling device for attaching and detaching the secondary seal 30 having the above structure will be explained with reference to FIG. FIG. 5 is a sectional view showing a state in which the rotor 31, stator 32, etc. in the casing 33 are removed and the handling device according to this embodiment is installed. A bracket 54 is attached to the lower side surface of the casing 33, and a pair of screw mechanisms 55 are attached to the bracket 54. This screw mechanism 55
A drive motor (not shown) that rotates the screw mechanism 55 is installed below the screw mechanism 55 . The above screw mechanism 5
A base 56 is detachably attached to the nut portion 55A of No. 5. A substantially cylindrical support body 57 is fixed onto the base 56 by positioning pins 58 and fastening bolts 59. Further, a secondary seal handling tool 60 is attached to the upper part of this support body 57. This secondary seal handling tool 60 can be moved up and down by a hydraulic mechanism 61 built into the support body 57. A claw member 62 is attached to the upper part of the secondary seal handling tool 60, and this claw member 62 is configured to be driven by a hydraulic mechanism 63 built into the secondary seal handling tool 60. That is, when the hydraulic mechanism 63 is driven to extend the shaft 63A upward, the central portion of the pawl member 62 is pulled upward, and as a result, the pawl member 62 is closed inward. In this state, it passes through the inner peripheral side of the secondary seal 30 and rises to a position above the secondary seal 30. Thereafter, when the shaft 63A of the hydraulic mechanism 63 is pulled downward, the claw member 62 engages with the upper end surface of the secondary seal 30 while opening. Further, a washer handling mechanism 64 is installed in the secondary seal handling tool 60. A wedge 65 is arranged at the upper end of this washer handling mechanism 64, and a hydraulic mechanism 63 of the secondary seal handling tool 60 is installed.
driven by That is, the hydraulic mechanism 63 opens the pawl member 62 and engages the upper end surface of the secondary seal 30, and at the same time the wedge 65 rises and the secondary seal 3
A washer 52 is placed in the groove 30A formed on the lower surface side of the
Insert while pushing. With this, washer 5
This configuration allows the secondary seal 30 to be removed by releasing the engagement between the secondary seal 2 and the casing 33. Note that reference numeral 68 in the figure indicates a guide roller attached to the upper outer periphery of the support body 57.

The operation will be explained based on the above configuration. First, the case where the secondary seal 30 is removed will be explained.
A support body 57 equipped with a secondary seal handling tool 60 is placed on a base 56 by positioning pins 58 and fastening bolts 5.
9, the drive motor is started to rotate the screw mechanism 55, and the support body 57 is inserted into the casing 33. Then, the support body 57 is fixed to the casing 33 with a fastening bolt 69. At this time, the pawl member 62 is raised by the hydraulic mechanism 63 and is closed inward (indicated by a two-dot chain line in the figure).
Further, the wedge 65 is lowered. Next, the hydraulic mechanism 61 is driven to raise the secondary seal handling tool 60 and cause the claw member 62 to pass through the inner circumferential side of the secondary seal 30. When the secondary seal handling tool 60 rises to a predetermined position, the hydraulic mechanism 63 is driven to remove the shaft 63.
A is lowered, thereby opening the claw member 62 and engaging its both side portions 62A with the upper end surface of the secondary seal 30. And in conjunction with this movement,
The wedge 65 of the washer handling mechanism 64 is raised to push and insert the washer 52 into the groove 30A of the secondary seal 30. By this operation, the washer 52 is bent upward as shown by the two-dot chain line in FIG. 4, and as a result, the engagement between the washer 52 and the casing 33 is released. In this state, the hydraulic mechanism 61 is operated to lower the secondary seal handling tool 60. At this time, since the washer 52 and the casing 33 are disengaged as described above, the secondary seal 30 can be removed downward without any hindrance. Then, the fastening bolt 69 is removed, the drive motor is driven to rotate the screw mechanism 55, and the support body 57 is pulled out from inside the casing 33. This completes the removal of the secondary seal 30. Thereafter, the secondary seal 30 is inspected or replaced, and the washer 52 is replaced. After completing this work, the installation work of the secondary seal 30 is started.

The installation work of the secondary seal 30 will be explained below. First, the pawl member 62 is raised and closed by the hydraulic mechanism 63, and in this state, the pawl member is passed around the inner circumference of the secondary seal 30 to place the secondary seal 30 on the wedge 65. Next, the support body 57 is inserted into the casing 33 by driving the drive motor. After insertion, the support body 57 is fixed to the casing 33 with a fastening bolt 69. Then, the hydraulic mechanism 61 is driven to raise the secondary seal handling tool 60, and the washer 52 of the secondary seal 30 is moved to the inner wall 33A of the casing 33.
, and is forcibly attached to the groove portion 51 . The outer peripheral edge of the forcibly attached washer 52 is supported by the groove 51 from below, thereby attaching the secondary seal 30 to the casing 33. The above is the secondary seal 30
The installation work has been completed. Then tighten bolt 6
9 and drive the drive motor to drive the support body 57.
is pulled out from inside the casing 33, and the rotor 31, stator 32, etc. are mounted inside the casing 33.

According to the internal pump handling device according to this embodiment, the attachment and detachment of the secondary seal 30 is performed using the claw member 62.
Since the secondary seal handling tool 60 can be operated remotely, the work can be done in a short time even in a narrow space.
In particular, in this embodiment, the wedge 65 of the washer 52 supporting the secondary seal 30 from below is inserted into the groove 30A of the secondary seal 30 to bend the washer 52 upward, so that the secondary seal 30 can be removed smoothly. Therefore, the secondary seal 30 can be easily attached and detached without damaging not only the secondary seal 30 and the washer 52 but also nearby members.

[Effects of the Invention] As explained above, according to the present invention, the secondary seal can be attached and detached with a simple structure without damaging the inner surface of the casing with a washer. As a result, the time required for maintenance and inspection of the internal pump can be shortened, which is extremely effective in improving the operating rate of the nuclear reactor.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams showing conventional examples.
The figure is a longitudinal cross-sectional view of an external recirculation boiling water reactor.
FIG. 2 is a longitudinal sectional view of an internal pump type boiling water nuclear reactor, FIG. 3 is a longitudinal sectional view of an internal pump, and FIGS. 4 and 5 are views showing an embodiment of the present invention. 4 is a detailed view of the portion indicated by the symbol A in FIG. 3, and FIG. 5 is a sectional view showing the state in which the internal pump handling device is installed in the casing. 21... Internal pump, 33... Casing, 55... Screw mechanism, 56... Base, 57...
...Support, 60...Secondary seal handling tool, 61...
Hydraulic mechanism, 62... Claw member, 63... Hydraulic mechanism,
64...Washer handling mechanism, 65...Wedge, 68
...Guide roller.

Claims (1)

[Claims] 1. A base that is movable up and down below the casing in which the motor section of the internal pump is housed, a support that is installed at the center of the upper surface of the base and inserted into the casing, and an upper part of the support. a secondary seal handling tool having a claw member that is movable up and down and that can be opened and closed for attaching and detaching the secondary seal ring of the internal pump; a secondary seal handling tool elevating means for protruding from the center hole of the secondary seal ring; a claw member driving means for opening the claw member to engage the claw member with the upper surface of the secondary seal ring; A wedge provided below the claw member and a washer attached to the lower surface of the secondary seal ring by moving the wedge upward are pressed and bent into a groove formed on the lower surface of the secondary seal ring, and the An internal pump handling device comprising wedge driving means for releasing the engagement between the washer and the engagement groove formed on the inner peripheral surface of the casing.