JPH0718947B2 - Stretch tube for internal pump and handling device for stretch nut. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to handling of a stretch tube and a stretch tube nut of an internal pump in a new boiling water reactor (hereinafter referred to as A-BWR). The present invention relates to a stretch tube and stretch tube nut handling device for an eggplant internal pump.

(Prior Art) Generally, in a boiling water reactor (BWR), a coolant recirculation system for forcibly feeding a coolant (for example, water, hereinafter referred to as coolant) of a reactor pressure vessel into a core is provided. It is provided. FIG. 5 is a view showing the structure of a conventional BWR, and reference numeral 1 in the drawing is a reactor pressure vessel. A reactor core 2 including a plurality of fuel assemblies and control rods is housed in a shroud 3 in the reactor pressure vessel 1. A water supply sparger 5 connected to the water supply pipe 4 is provided above the core 2, and a steam separator 6 and a steam dryer 7 are further provided above the water supply sparger 5.

On the other hand, a plurality of jet pumps 8 are installed in the downcomer portion formed by the shroud 3 and the inner wall of the reactor pressure vessel 1. These jet pumps 8 jet the cooling water supplied from the recirculation pump 10 through the coolant recirculation system pipe 9 as a jet flow below the core 2. In the figure, reference numeral 11 is a main steam pipe for taking out steam generated in the reactor pressure vessel 1, and reference numeral 12 is a control rod.
A control rod drive mechanism for controlling the output of the nuclear reactor by inserting 13 into the core 2.

In the BWR having such a configuration, the cooling water supplied from the water supply pipe 4 into the reactor pressure vessel 1 flows out from the water supply sparger 5, flows down the downcomer part, is sucked by the recirculation pump 10, and is connected to the recirculation system piping. It is supplied to the jet pump 8 via 9. Further, this jet pump 8 enables the core 2
And is forcedly sent into the core 2.
When the cooling water forcedly fed into the core 2 rises in the core 2, the temperature of the cooling water rises due to its nuclear reaction heat and becomes a two-phase flow state of water and steam. The cooling water in the two-phase flow state is steam-water separator 6
It is introduced into the inside and separated into water and water. The separated steam is introduced into the steam dryer 7 and dried to become dry steam. This dry steam is the main steam pipe connected to the reactor pressure vessel 1.
It is transferred to a turbine (not shown) via 11 and is used for power generation there. The steam that has worked in the turbine is introduced into a condenser (not shown) to be condensed water, and is supplied as low-temperature cooling water into the reactor pressure vessel 1 through the water supply pipe 4.
The water separated by the steam separator 6 flows down in the downcomer part together with the water supplied from the water supply sparger 5, and the recirculation pump
Aspirated by 10. The same cycle is repeated thereafter.

By the way, in such a conventional BWR, a recirculation pump 10 for supplying cooling water as a driving flow to the jet pump 8 is installed outside the reactor pressure vessel 1, and some accident or the like occurs. When the recirculation system pipe 9 is broken by this, the cooling water will flow out of the reactor pressure vessel 1.
Such outflow of cooling water significantly lowers the core cooling performance, and may damage the fuel rods constituting the fuel assembly. Therefore, in the conventional BWR, the core 2
An emergency core cooling system is installed separately for emergency cooling. However, when such an emergency core cooling system is installed, there is a problem that the amount of equipment, pipes, etc. increases, the configuration becomes complicated, and the plant becomes larger.

Therefore, the above-mentioned A-BWR is considered. This A-BWR is a so-called internal pump type BWR, and has a structure in which an internal pump is housed in the reactor pressure vessel 1. The structure of the A-BWR will be described below with reference to FIGS. 6 and 7. Figure 6 shows A-
FIG. 7 is a sectional view showing the structure of the BWR, and FIG. 7 is a sectional view showing the structure of the internal pump. The same parts as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted. Reference numeral 20 in the figure is an internal pump. A plurality of the internal pumps 20 are installed in the lower portion between the reactor pressure vessel 1 and the shroud 3 at equal intervals in the circumferential direction. As shown in FIG. 7, this internal pump 20 is composed of a pump section 21 and a motor section 22. The pump unit 21 includes an impeller 23, a diffuser 24, a diffuser wear ring 25, and the like. The impeller 23 is a drive shaft
The motor unit 22 is connected via 26. The diffuser 24 is a nozzle projecting from the bottom of the reactor pressure vessel 1.
It is fixed to the upper part of 1a by a stretch tube 27. The stretch tube 27 is fixed by a stretch tube nut 28. A secondary seal 29 is installed below the stretch tube nut 28.

The motor unit 22 is composed of a rotor 30, a stator 31 and the like. The components of the motor unit 22 are such that the tip portion is inserted into the nozzle 1a and the tip portion is inserted into the reactor pressure vessel 1 It is housed in a pump casing 32 welded to the. Cooling water circulates in the pump casing 32 through a circulation pipe 33 to prevent the motor unit 22 from being burned.

Since the A-BWR having such an internal pump 20 does not have a structure having a recirculation pump outside the reactor pressure vessel 1 like the BWR described above, a structure equivalent to a conventional recirculation system piping is required. do not do. Therefore, the installation space in the primary containment vessel, the reactor containment vessel, can be significantly reduced, and the assumed fracture cross-sectional area in the liquid phase portion can be greatly reduced. Further internal pump
As for 20 as well, the motor unit 22 is housed in the pump casing 32 having excellent watertightness and does not require a sliding type shaft sealing device, so the configuration is simple and the possibility of leaking reactor water is small, Not only reliability but also maintainability is excellent.

However, even in the case of such an internal pump 20, it is necessary to inspect it regularly. The inspection work of this internal pump will be described below. The work of removing the internal pump 20 is performed from above and below the reactor pressure vessel 1. In that case, first, the impeller 23 is removed together with the drive shaft 26 from above the reactor pressure vessel 1, and the opening of the diffuser 24 is opened. To prevent the inflow of reactor water. Next, after discharging the reactor water in the pump casing 32, the motor unit 22 is removed from below the reactor pressure vessel 1.
And the secondary seal 29 and stretch tube nut
28 is removed from below the reactor pressure vessel 1. Next, the lower surface of the pump casing 32 is sealed to prevent the reactor water from flowing out, and then the diffuser 24, the diffuser waring 25 and the stretch tube 27 are removed from above the reactor pressure vessel 1.

However, the work for removing or installing such an internal pump needs to be performed remotely in a narrow space, and it is expected that the work will be difficult. In particular, since the stretch tube nut 28 is tightened with a large torque, it is difficult to attach / detach it, and as a result, the work time required for maintenance and inspection work is lengthened and there is a concern that workers will be exposed to radiation and the plant operation It is not preferable for improving the rate.

(Problems to be solved by the invention) As described above, attachment / detachment work of an internal pump, particularly attachment / detachment of a stretch tube nut is accompanied by difficulty, which prolongs the work, resulting in worker's exposure and plant operation rate. Therefore, the present invention has been made based on this point, and the purpose thereof is to easily handle the stretch tube and the stretch tube nut, thereby simplifying the work. It is another object of the present invention to provide a stretch tube and stretch tube nut handling device for an internal pump, which can shorten the working time.

[Structure of the Invention] (Means for Solving Problems) That is, the apparatus for handling the stretch tube and stretch tube nut of the internal pump according to the present invention is
A base that is attached to the bottom of the pump casing of the internal pump, a stretch tube tensioning device that is attached to this base and applies tension to the stretch tube, and a stretch tube nut that is attached to the above base and pushes up the stretch tube nut to stretch it. A stretch tube nut rotating device for screwing a tube into the stretch tube nut to drive the stretch tube nut, a spring mechanism for urging the stretch tube nut upward, and a spring mechanism interposed between the spring mechanism and the lower surface of the stretch tube nut. A bearing mechanism is provided.

(Operation) In other words, when attaching or detaching the stretch tube and the stretch tube nut, first, the base on which the entire handling device is attached is inserted into the pump casing and fixed. Next, the stretch tube is pulled by the stretch tube tension device, and in that state, the stretch tube nut is rotated by the stretch tube nut rotation device. When the stretch tube and the stretch tube nut are screwed together, while the stretch tube is pulled by the stretch tube tension device, the stretch tube nut rotating device pushes up the stretch tube nut and a part of it becomes a stretch tube. It is operated by rotating the screwed state.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. The structures of the A-BWR and the internal pump will be described with reference to FIGS. 6 and 7 used for explaining the conventional example. FIG. 1 is a sectional view showing the overall structure of a stretch tube and stretch tube nut handling device according to this embodiment, and reference numeral 101 in the figure is a base. The entire apparatus is attached to this base 101. Base 1 above
01 is fixed to the lower surface of the pump casing 32 by tightening bolts 102 and nuts 103. In the figure, reference numeral 104 is a washer. A cylindrical support 105 is fixed to the base 101. In the figure, a part of the support 105 is cut away. A stretch tube tension device 106 and a stretch tube nut rotation device 1 are provided in and on the support 105.
07 are installed respectively.

The stretch tube tension device 106 will be described. First, reference numeral 108 in FIG. 2 is a shaft. As shown in FIG. 1, the lower end of the shaft 108 projects from the base 101, and thus it is moved up and down by rotating it manually. In the figure, reference numeral 109 is a joint,
The shaft 108 is assembled by this joint 109 and another joint not shown. As shown in FIG. 2, a fan-shaped pin 111 is formed at the tip of the shaft 108 via a link 110.
Are connected. To explain this in more detail, as shown in FIG. 4, the four pins 111 are installed,
Each of them is connected to the shaft 108 via the link 110. On the other hand, the stretch tube 27 corresponding to the above pin 111
An annular groove 112 is formed in the groove. Therefore the shaft 108
The pin 111 is retracted toward the center in the radial direction when the shaft 108 is raised, but projects outward in the radial direction when the shaft 108 is lowered. As a result, the pin 11 engages with the groove 112 and the stretch tube 27 is pulled downward. As means for moving the shaft 108 up and down, there are hydraulic means other than the manual operation. That is, as shown in FIG. 1 and FIG.
13 is fixed, and a cylinder 114 is installed on the outer circumference of this piston 113. Therefore, when the hydraulic pressure is applied to the inside of the cylinder 114, the shaft 108 moves up and down via the piston 113, and the pin 111 is projected and retracted. In addition, a load meter is provided on the outer periphery of the shaft 108 below the cylinder 114.
115 are installed. A cover 116 is installed above the shaft 108, and a spring 117 that constantly biases the shaft 108 upward is installed in the cover 116. A hanging hook 118 is fixed to the upper end of the cover 116.

Next, the configuration of the stretch tube nut rotating device 107 will be described. An annular member 121 is fixed by bolts 122 above the support body 105, and a stretch tube nut rotating tool 123 is rotatably installed on the inner peripheral side of the annular member 121. Grooves are formed in the stretch tube nut rotating tool 123 at equal intervals in the circumferential direction, and the convex portions formed on the outer circumference of the stretch tube nut 28 mesh with the grooves. Therefore, when the stretch tube nut rotating tool 123 rotates, the stretch tube nut 28 also rotates. A threaded portion is formed on the inner peripheral surface of the stretch tube nut rotating tool 123, and the gear 124 is screwed into this threaded portion. The gear 124 is fixed to the shaft 125. When this shaft 125 is rotated, the above gear 1
The stretch tube nut rotator 123 rotates via 24, which causes the stretch tube nut 27 to rotate. The shaft 125 is rotated by the drive motor 126 shown in FIG. 3, and the rotational force of the drive motor 126 is transmitted to the shaft 125 via the gear mechanism 127. Further, reference numeral 128 in FIG. 3 is a switching lever, and the switching lever 128 switches between rotation by the drive motor 126 and rotation by manual operation. The structure of the gear mechanism 127 will be described in more detail below.
Gear 127a is fixed to this gear 127a.
127b is meshed. The gear 127b is fixed to the shaft 129, and another gear 127c is fixed to the shaft 129. A gear 127d fixed to the shaft 125 meshes with the gear 127c. The state shown in the figure is the manual mode, and the gear 127c is generated by manually rotating the shaft 129 using a jig or the like not shown.
And rotate shaft 125 via 127d. When the drive motor 126 is used for rotation, the switching lever 128 may be operated to mesh the gear 127d with the gear 127b.

Reference numeral 130 in the figure denotes a shaft, and a bearing 132 is attached to the tip of the shaft 130. This bearing 1
32 is composed of a fixed part 132a and a rotating part 132b.
Above the stretch tube nut 28 is located.
A spring 134 is mounted on the upper end of the shaft 130, and the bearing 132 is biased upward by the spring 134. This pushes up the stretch tube nut 28 and pushes the end of the stretch tube nut 28.
It is screwed to 27. A spring 131 is also attached to the lower end of the shaft 130 as shown in FIG. 3, which holds the position of the shaft 130.

The operation will be described based on the above configuration. First, a case where the stretch tube nut 28 is attached to the stretch tube 27 will be described. First, the entire apparatus is raised by a crane device or the like (not shown) via the hook 118, and the base 101 is fixed to the pump casing 32 with the bolt 102 and the nut 103. Next, a hydraulic hose is connected to a hydraulic connection terminal (not shown) at the lower end of the base 101, and a cable is also connected to the load meter 115. These hydraulic hoses and cables are connected to a control device (not shown).

Next, the stretch tube pulling operation is started. The shaft 108 is rotated by hydraulic operation to lower the shaft 108. As a result, the pin 111 projects toward the outer periphery in the radial direction, engages with the groove 112 of the stretch tube 27, and pulls the stretch tube 27 downward. At that time, when the signal from the load meter 115 is monitored and a predetermined load is indicated, the drive of the shaft 108 is stopped. Next, the stretch tube nut 28 is pushed upward by the spring 134 via the bearing 132, and the tip thereof is screwed into the stretch tube 27. At this time, if the pushing up is not successful, it may be manually pushed up through the lower end of the shaft 130. In this state, the rotating operation by the stretch tube nut rotating device 107 is started. That is, the drive motor 126 rotates the shaft 125 via the gear mechanism 127. This shaft
The rotation of 125 causes the gear 124 to rotate, which causes the stretch tube nut rotator 123 to rotate. By the rotation of the stretch tube nut rotating tool 123, the stretch tube nut 28 is rotated and screwed into the stretch tube 27. The above is the mounting operation. In this series of operations, the shaft 108 can be manually operated, and the operation of the shaft 125 can be performed by the switching lever 1.
It is possible to operate manually by 28.

Further, when removing the stretch tube nut 28 from the stretch tube 27, the above operation may be performed in reverse.

According to this embodiment, the following effects can be obtained. That is, in the extremely narrow space inside the pump casing 32, the work of attaching and detaching the stretch tube nut 28 can be easily performed by remote control. Further, all the handling devices according to the present embodiment are put in and out from below the pump casing 32. In addition, it can be disassembled and assembled, and its handling is extremely easy. Further, in the present embodiment, the bearing 132 is provided between the stretch tube nut 28 and the spring 134 as a spring mechanism for urging the stretch tube nut 28 upward so that the spring 134 is attached to the rotating stretch tube nut 28. The power can be transmitted smoothly.

[Advantages of the Invention] As described in detail above, according to the stretch tube and stretch tube nut handling device of the internal pump of the present invention, the work of attaching and detaching the stretch tube nut is facilitated and the working time thereof is shortened. Therefore, the time required for maintenance and inspection work is shortened, which is extremely effective in reducing the radiation exposure of workers and improving the operating rate of plants. Further, the biasing force of the spring mechanism can be smoothly transmitted to the rotating stretch tube nut.

[Brief description of drawings]

1 to 4 are views showing an embodiment of the present invention.
The figure is a cross-sectional view showing the whole handling equipment, and Fig. 2 is II of Fig. 1.
FIG. 3 is a detailed view of the parts, FIG. 3 is a detailed view of the III part of FIG. 1, FIG. 4 is a sectional view taken along the line IV-IV of FIG. 2, and FIG. 5 is a structure of a boiling water reactor. A sectional view, FIG. 6 is a sectional view showing a configuration of a new boiling water reactor, and FIG. 7 is a sectional view showing a configuration of an internal pump. 20 …… Internal pump, 27 …… Stretch tube, 28 …… Stretch tube nut, 32 …… Pump casing, 101 …… Base, 106 …… Stretch tube tensioning device, 107 …… Stretch tube nut rotating device.

Claims (2)

[Claims] 1. A base that is attached to the lower surface of a pump casing of an internal pump, a stretch tube tensioning device that is attached to the base and applies tension to a stretch tube, and a stretch tube nut that is attached to the base and pushes up a stretch tube nut. Between the stretch tube nut rotating device that rotates the stretch tube nut by screwing the stretch tube nut and the stretch tube together, the spring mechanism that urges the stretch tube nut upward, and the spring mechanism and the bottom surface of the stretch tube nut. A stretch tube and stretch tube nut handling device for an internal pump, comprising a bearing mechanism interposed therebetween. 2. An internal according to claim 1, wherein the stretch tube pulling device pulls downward with the pin fitted in a recess formed in the stretch tube. Pump stretch tube and stretch tube nut handling device.