JPS6293693A - Internal pump treater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an internal pump handling device for attaching and detaching an internal pump in a boiling water nuclear reactor, and particularly relates to an internal pump handling device for attaching and detaching an internal pump diffuser wear ring. Regarding the equipment for performing.

[Technical Background of the Invention] Generally, a boiling water nuclear reactor is provided with a coolant recirculation system for forcibly feeding the coolant in the reactor pressure vessel into the reactor core. FIG. 1 is a diagram showing a schematic configuration of a conventional boiling water nuclear reactor, and reference numeral 1 in the figure indicates a reactor pressure vessel. A reactor core 2 consisting of a plurality of fuel assemblies (not shown) is formed within the reactor pressure vessel 1 and is housed within a cylindrical shroud 3. A water supply sparge V5 connected to the water supply pipe 4 is provided above the core 2, and a steam separator 6 and a steam dryer 7 are provided roughly above it.

On the other hand, a plurality of jet pumps 8 are provided within the downcomer formed by the shroud 3 and the inner wall of the reactor pressure vessel 1. These jet pumps 8 jet the coolant supplied from the recirculation pump 10 via the coolant recirculation pipe 9 to the lower part of the reactor core 2 as a jet stream. In the figure, reference numeral 11 indicates a main steam pipe for extracting steam generated within the reactor pressure vessel 1, and 12 indicates a control rod 1.
3 into the reactor core 2 to control the output of the reactor.

In such a boiling water reactor, water as a coolant supplied from the water supply pipe 4 into the reactor pressure vessel 1 flows out from the water supply sparger 5, descends into the downcomer, and is sucked by the recirculation pump 10. The coolant is supplied to the jet pump 8 via the coolant recirculation pipe 9. Then, it is ejected downward from the reactor core 2 by the jet pump 8 and is forcibly fed into the reactor core 2 . The coolant sent into the core 2 is heated during its ascent, and flows out above the core 2 as a two-phase flow of water and steam. The coolant flowing above the core 2 is transferred to the steam separator 6.
Steam and water are separated, and only the separated steam is sufficiently dried in a steam dryer 7 and then sent from a main steam pipe 11 to a power generation turbine (not shown).

The coolant fed to the power generation turbine passes through a condenser (not shown) and is again supplied from the water supply pipe 4 into the reactor pressure vessel 1 as low-temperature return water. The water separated by the steam separator 6 descends into the downcomer together with the water supplied from the water supply sparger 5, is sucked by the recirculation pump 10, and flows through the flow path described above.

By the way, 1. In such a conventional external recirculation boiling water reactor, the recirculation pump 10 for supplying coolant as a driving flow to the jet pump 8 is provided outside the reactor pressure vessel. If the recirculation pipe 9 ruptures due to some kind of accident, the coolant will flow out of the reactor pressure vessel, significantly reducing core cooling, and possibly causing fuel rod breakage.

Therefore, in order to prevent such a danger, in a conventional boiling water nuclear reactor, an emergency core cooling system for emergency cooling of the reactor core 2 is separately provided.

However, when such an emergency core cooling system is provided, the number of piping and auxiliary equipment increases significantly, making the entire nuclear reactor system complex and large.

For this reason, in recent years, a so-called internal pump type boiling water reactor has been proposed in which a plurality of axial flow pumps are disposed in the lower head of the reactor pressure vessel. FIG. 2 is a diagram showing a schematic configuration of an internal pump boiling water reactor (A-BWR>), in which the same parts as in FIG. 1 are given the same reference numerals.

In the figure, reference numeral 20 denotes a plurality of internal pumps attached to the lower mirror part of the reactor pressure vessel 1, and these internal pumps 20 are connected to the pump part 21 as shown in FIG.
and a motor section 22. The above pump part 2
1 consists of an impeller 23, a diffuser 24, a diffuser ring 25, etc., and the impeller 23 is connected to a drive shaft 26.
It is connected to the motor section 22 via. The diffuser 24 is fixed by a stretch tube 27 to the upper part of a nozzle 1a protruding from the bottom of the reactor pressure vessel 1, and the stretch tube 27 is fixed by a stretch dupe nut 28. Note that a secondary seal 29 is provided at the bottom of the stretch tube nut 28.

The motor section 22 is composed of a rotor 30, a stator 31, etc., and these motor section components are housed in a bomb housing 32 whose tip is inserted into the nozzle 1a and welded to the reactor pressure vessel 1. . Cooling water is circulated within the pump casing 32 through a circulation pipe 33 to prevent the motor section 22 from burning out.

Eight-BWR with such an internal pump 20
Since the reactor does not have a recirculation pump 10 outside the reactor pressure vessel 1 unlike the external recirculation type boiling water reactor shown in FIG. 1, it does not require the recirculation pipe 9. As a result, the installation space for the recirculation equipment in the secondary containment vessel can be significantly reduced, and the expected fracture cross-sectional area in the liquid phase can be reduced, making it possible to make the emergency core cooling system guest room smaller than before. becomes. Furthermore, the motor section 22 of the internal pump 20
Since it is housed in a pump casing 32 with excellent watertightness, it does not require a sliding shaft sealing device, has a simple structure, has a small possibility of reactor water leakage, and has excellent maintainability and reliability.

[Problems with Background Art] By the way, with the adoption of the highly reliable A-BWR, maintenance and inspection work on the internal pump 20 must also be performed periodically. This maintenance and inspection work for the internal pump is performed by removing the internal pump 20 from the reactor pressure vessel 1. The internal pump removal work is performed from above and below the reactor pressure vessel 1, and the work is performed in the following order. First, the impeller 23 and the drive shaft 26 are removed from above the reactor pressure vessel 1, and the opening of the diffuser 24 is closed to prevent the inflow of reactor water. Next, the pump casing 32
After draining the reactor water inside, the motor section 22 is removed from below the reactor pressure vessel 1. Then, the secondary seal 29 and stretch tube nut 28 are removed from below the reactor pressure vessel 1.

Next, after sealing the lower surface of the pump casing 32 to prevent reactor water from flowing out, the diffuser 24. This is the order in which the diffuser wear ring 25 and stretch tube 27 are removed.

However, the removal and installation of such an internal pump is expected to be difficult because the work must be done remotely in a confined space. In particular, the disc outer ring 25 incorporated in the upper part of the disc f24 is also a wear member and is smaller than other parts, so it is expected that it will be very difficult to attach and remove it. For this reason, maintenance and inspection of the internal pump takes a long time, and as a result, there is a risk that the operation of the nuclear reactor will be stopped for a long period of time, resulting in a decrease in the operating rate.

[Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and its purpose is to easily attach and detach the diffuser wear ring of an internal pump, and to reduce the time required for maintenance and inspection of the internal pump. The object of the present invention is to provide an internal pump handling device that can be shortened and is extremely useful in practice.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention has a plurality of movable cylinders suspended from above the reactor pressure vessel and sliding on the inner wall surface of the reactor pressure vessel and the outer wall surface of the shroud. a main body having a guide roller; a positioning guide provided at the bottom of the main body and positioned on the upper surface of the diffuser of the internal pump; and a diffuser wear provided on the main body for grasping the diffuser wear ring of the internal pump. The device is characterized by being equipped with a ring gripping mechanism.

[Embodiments of the Invention] The present invention will be described in detail below with reference to the drawings. 4 and 5 do not show one embodiment of the present invention, and reference numeral 41 in the drawings indicates that a control ball and a wire rope (not shown) are used to move the inside of the reactor pressure vessel 1 from the working floor above the reactor pressure vessel. This is the main body that is suspended. In the upper part of this main body 41, a plurality of guide rows 542 are arranged on the inner wall surface 1b of the reactor pressure vessel 1.
and are provided so as to protrude in the horizontal direction so as to come into contact with the outer wall surface 3a of the shroud 3. Also, at the bottom of the main body 41, there is a diffuser wear ring 2 of the internal pump.
A diffuser wear ring gripping mechanism 43 for gripping the diffuser wear ring 5 and a positioning guide 44 positioned on the upper surface of the diffuser wear ring 25 are provided. The diffuser wear ring gripping mechanism 43 consists of an air cylinder 45 provided in the main body 41 and two arm parts 47.47 connected to the piston rod 46 of the air cylinder 45, and the tip of the arm part 47.47. On the other hand, claw members 48 and 48 that grip the groove portion 25a on the upper side surface of the diffuser wear ring 25 are provided so as to be openable and closable. Further, the positioning guide 44 is accurately positioned by four locking pins 25b installed on the upper surface of the differential user wear ring 25. A lever 49 is provided at the top of the positioning guide 44, and when the lever 49 is pushed up by the locking bin 25b, the limit switch 50 is activated, and a lamp (not shown) incorporated in the top of the device is activated. is now lit.

Next, the operation of this device configured as described above will be explained. First, the main body 41 is suspended into the reactor pressure vessel 1 from above using an operating ball and a wire rope. The main body 41 suspended in the reactor pressure vessel 1 is guided by guide rollers 42 provided on the inner wall 1b of the reactor pressure vessel 1.
It is lifted directly above the internal pump using the guide rail (not shown) as a guide. Then, the positioning guide 44 of this device is positioned on the upper surface of the internal pump's differential user wear ring 25 by the locking bin 25a, the limit switch 50 is activated, and the lamp is turned on. At this time, the diffuser wear ring gripping mechanism 43
The claw member 48 is in an open state and is located on the upper side surface of the diffuser wear ring 25. Then, in this state, by driving the air cylinder 45 and pulling up the piston rod 46, the arm part 47 is pulled up, and the claw member 48 is moved to the diffuser wear ring 2.
It fits into the groove 25b of No.5. Then, in this state, the wire lobe is wound up and the main body 41 is pulled up from inside the reactor pressure vessel 1, thereby removing the diffuser wear ring 25 from the internal pump.

As described above, in this embodiment, the attachment and detachment of the diffuser wear ring 25 is carried out by the diffuser wear ring gripping mechanism 4.
3 and the positioning guide 44,
The diffuser wear ring 25 can be attached and detached in a short time even by remote control in a narrow place.

Note that the present invention is not limited to the above embodiments.

For example, in the above embodiment, the air cylinder 45 is used as a means for driving the arm portion 47, but a hydraulic cylinder or the like may also be used. Moreover, although the guide rail of the guide roller 42 that guides the main body 41 directly above the internal pump is provided on the inner wall 1b of the reactor pressure vessel 1, it may be provided on the outer wall of the shroud.

[Effects of the Invention] As described above, according to the present invention, there is provided a plurality of guide rollers that are suspended into the pressure vessel from above the reactor pressure vessel and slide on the inner wall surface of the pressure vessel and the outer wall surface of the shroud. a main body, a positioning guide provided at the bottom of the main body for positioning the main body on the upper surface of the diffuser of the internal pump, and a diffuser wear ring gripping mechanism provided for the main body for grasping the diffuser wear ring of the internal pump. Since the configuration has the following,
The diffuser wear ring can be easily attached and detached, reducing maintenance and inspection time for the internal pump.
It is possible to provide an internal pump handling device that is extremely useful in practice.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional external recirculation boiling water reactor, Figure 2 is a schematic diagram of an internal pump boiling water reactor, and Figure 3 is a schematic diagram of an internal pump. 4 is a longitudinal sectional view of a diffuser wear ring attaching/detaching device showing one embodiment of the present invention, and FIG. 5 is a sectional plan view of the same device. DESCRIPTION OF SYMBOLS 1...Reactor pressure vessel, 2...Reactor core, 3...Shroud, 6...Steam water separator, 7...Steam dryer, 2
0... Internal pump, 25... Diffuser wear ring, 41... Main body, 42... Guide roller, 43... Diffuser wear ring gripping mechanism, 4
4...Positioning guide. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A main body having a plurality of guide rollers that are suspended from above into the reactor pressure vessel and slide on the inner wall surface of the pressure vessel and the outer wall surface of the shroud, and a diffuser of the internal pump provided at the lower part of the main body. An internal pump handling device comprising: a positioning guide positioned on an upper surface; and a diffuser wear ring gripping mechanism provided on the main body for gripping a diffuser wear ring of the internal pump.