JP2896443B2 - Cleaning device and cleaning method for internal pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to cleaning of an internal pump for removing a cladding adhered to a stretch tube or an internal pump nozzle of an internal pump provided in a boiling water reactor. The present invention relates to an apparatus and a cleaning method.

[Conventional technology]

In a boiling water reactor (BWR), an improved boiling water reactor (ABWR) in which a recirculation pump (internal pump) is placed below the reactor pressure vessel and coolant is forced to circulate in the reactor pressure vessel Has been developed (Japanese Patent Laid-Open No. 64-7819).
No. 5).

The ABWR, which has such an internal pump in the lower mirror part of the reactor pressure vessel, does not have an external recirculation system unlike the conventional BWR, so the piping space in the reactor containment vessel can be greatly reduced and emergency use is also possible. The capacity of the core cooling system can be reduced.

[Problems to be solved by the invention]

However, when the internal pump is operated for a long period of time, the pump drive shaft, the stretch tube surrounding the pump and the stretch tube and the pump nozzle formed on the reactor pressure vessel wall for mounting the pump become radioactive. There is a tendency that the cladding gradually adheres and the internal pump becomes highly radioactive. Further, the clad adhered to the stretch tube may cause a performance defect such as a fluctuation in the driving speed of the driving shaft. Also, the internal pump needs to be regularly inspected. At this time, it is necessary to pull out the drive shaft from the stretch tube. At this time, the pulling out of the drive shaft may be caused by the cladding adhered to the stretch tube. Inspection of the internal pump is usually performed with a TV camera or the like while the stretch tube is installed below the pressure vessel.

However, in the related art, there is no means for effectively removing the radioactive clad attached to the internal pump stretch tube installed in the lower part of the pressure vessel. . Therefore, it has been very difficult to sufficiently remove the cladding of the internal pump installed below the deep pressure vessel.

An object of the present invention is to clean an internal pump while being installed in a lower part of a reactor pressure vessel and an internal pump that can quickly and reliably wash an activated clad attached to a nozzle in which the internal pump is installed. An apparatus and a cleaning method are provided.

[Means for solving the problem]

In order to achieve the above object, the present invention relates to a cleaning device for remotely cleaning a stretch tube or a pump nozzle of an internal pump provided at a lower part of a reactor pressure vessel, wherein the pressure vessel of an internal pump casing is provided. A holding member detachably attached to an outer portion and sealing the inside, a cleaning tool held by the holding member and inserted into the internal pump casing to clean the stretch tube or the nozzle, and A discharge device for discharging the internal pump casing to the outside of the internal pump casing.

In the cleaning device, the cleaning tool preferably includes a brush that rubs the stretch tube or the pump nozzle, and a driving unit that drives the brush. Alternatively, the cleaning tool preferably includes a watering nozzle for watering the stretch tube or the pump nozzle, and a water supply unit for supplying water to the watering nozzle. Alternatively, the cleaning tool preferably includes an ultrasonic vibrator and an ultrasonic oscillator.

Further, according to the present invention, a step of separating an impeller from a drive shaft of an internal pump from an upper part of a reactor pressure vessel, a step of removing a pump component in an internal pump casing to the outside, and a cleaning method according to claim 1. An internal including a step of mounting the apparatus on an internal pump casing, a step of driving the cleaning apparatus to wash a stretch tube or a pump nozzle, and a step of discharging cleaning water to the outside of the internal pump casing. This is a method of cleaning the pump.

[Action]

When the pump components such as the drive shaft of the internal pump are removed, the pump casing remains. By inserting a cleaning tool into the pump casing and attaching the holding member to the pump casing, a cleaning operation for removing the clad attached to the stretch tube or the like becomes possible. When the cleaning tool is driven by the driving unit, the cleaning member removes the clad. After the cleaning, the cleaning water containing the clad is discharged from the pump casing to the outside of the pump casing by a drainage means, and a predetermined drainage treatment is performed. After the cleaning operation is completed, the holding member is removed from the pump casing, and the pump components are reassembled in the pump casing. Thereby, the cladding can be removed.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the structure of the ABWR will be described with reference to FIGS.

FIG. 6 is a cross-sectional view of an ABWR showing one example thereof, in which 1 is a reactor pressure vessel. A reactor core 2 including a large number of fuel assemblies (not shown) is formed in the reactor pressure vessel 1.
It is housed in a cylindrical shroud 3. A water supply sparger 5 connected to a water supply pipe 4 is provided above the reactor core 2, and a steam / water separator 6 and a steam dryer 7 are further provided above the water supply sparger 5. Further, a plurality of internal pumps 8 are provided in a lower mirror portion of the reactor pressure vessel 1.

These internal pumps 8 are composed of a pump section 11 and a motor section 12, as shown in FIG. 7, and the pump section 11 is driven by the motor section 12 to forcibly circulate the coolant in the reactor pressure vessel 1. It is made to let. The pump section 11 includes an impeller 13, a diffuser 14, a diffuser wear ring 15, and the like. The impeller 13 is connected to the motor section 12 via a drive shaft 16.

The diffuser 14 is provided at the upper end of a nozzle 17 provided in the lower mirror of the reactor pressure vessel 1 and is fixed by a stretch tube 18. The stretch tube 18 is provided at an upper part in the pump casing 20 and is fixed by a stretch tube nut 19. And
A secondary seal 21 is provided below the stretch tube nut 19 to prevent coolant from flowing into the motor unit 12.

On the other hand, the motor section 12 includes a rotor 22 and a stator 23 and the like, and is housed in a pump casing 20.
At the lower end of the pump casing 20, a pump casing 20 is provided.
A main flange 24 for closing a lower end opening of the pump casing 20 is attached. The main flange 24 includes a plurality of stud bolts 25 provided at a lower end of the pump casing 20 and a main flange mounting nut 26 screwed to the stud bolts 25. , And is firmly fastened to the lower end of the pump casing 20.

The cleaning device according to the present invention is used by removing pump components such as the drive shaft 16, the stator 23, and the impeller 13 from the inside of the pump casing 20, and attaching the pump to the components.

FIG. 1 shows an internal pump cleaning apparatus according to an embodiment of the present invention. This cleaning device 35 has a first
As shown in the figure, a stud bolt 25 and a main flange mounting nut 26 are installed in a pump casing 20 at a lower portion of the reactor pressure vessel 1. The cleaning device 35 includes a brush 28 for removing the clad adhered to the inside of the stretch tube 18 of the internal pump in a state where the brush is installed on the pump nozzle 17, a rod 29, and the brush 28 damage the stretch tube. Outer guide 30 that engages inside the pump casing 20 to guide the rod 29
And an air cylinder 31 for moving the brush 28 up and down, a compressor 33 for driving the air cylinder 31, a drain hose 32 for draining the separated clad, and a drainage treatment provided with a drainage pump and a filter. A mechanism 34 is provided. Outer guide that engages with pump casing 20
An O-ring 36 is provided at the top of the unit 30, an O-ring 37 is provided within the outer guide 30 on which the rod 29 slides, and an O-ring 38 is provided between the outer casing 30a in which the air cylinder 31 is installed and the outer guide 30. It is watertight.

In the embodiment of the present invention configured as described above, the clad attached to the internal pump stretch tube 18 installed in the pump casing 20 at the lower part of the reactor pressure vessel 1 is brushed by a brush 28 through a rod 29. By moving the cylinder up and down, it can be easily separated.
Furthermore, by performing drainage treatment by a drainage treatment mechanism 34 provided with a drainage pump and a filter via a drainage hose 32, the clad can be quickly and reliably washed, and the internal pump can be protected from the clad.

Further, in the present embodiment, the clad attached to the internal pump is cleaned by moving the brush 28 up and down. However, the operation of the brush 28 is not necessarily limited to the up and down movement, and as shown in FIG. By providing a motor 40 and a drive source 41 instead of the air cylinder 31 and the compressor 33 of the above embodiment, and rotating the rod 29 via the speed reducer 39, by rotating the brush connected to the rod 29, The same effects as above can be obtained.

Next, another embodiment of the present invention will be described with reference to FIG. The same parts as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The apparatus of this embodiment has a structure in which the clad can be cleaned using pressure water instead of the brush 28 of the previous embodiment. The feature of the apparatus of the present embodiment is that a watering nozzle 42 is provided as a cleaning tool, and is connected to the rod 29 from a pressure water supply device 44 via a flexible tube 45 and a pressure water supply pipe 43 passing through the inside of the rod 29. The pressurized water is supplied to the spray nozzle 42, and the pressure water is sprayed from the spray nozzle 42 to the internal pump to remove the clad. Accordingly, high pressure water can be supplied by a high pressure pump by a cleaning tool having a nozzle for jetting high pressure water, and the high pressure water can forcibly peel off the clad adhered to the stretch tube of the internal pump.

Further, another embodiment of the present invention will be described with reference to FIG.

The apparatus of the present embodiment is an ultrasonic cleaning tool provided with an ultrasonic vibrator 49 instead of the brush 28 and the water spray nozzle 42 of the previous embodiment.
According to 46, the structure is such that the cladding can be cleaned by a shock wave of cavitation as a physical force using ultrasonic waves.

The feature of the apparatus of the present embodiment is that, as a cleaning tool, an ultrasonic cleaning tool 46 provided with an ultrasonic vibrator 49 is provided.
49 is connected to an ultrasonic oscillator 48 via a cable 47. The cladding of the internal pump can be removed by ultrasonic waves by the cleaning device 35 of the present internal pump, and the same effect as in the above embodiment can be obtained.

FIG. 5 shows the cleaning apparatus of the embodiment shown in FIG.
This shows that the clad attached to the pump nozzle 17 provided in the lower part of the reactor pressure vessel 1 can be removed. The effect is the same.

In the above embodiment, the configuration in which the cleaning tool and the wastewater treatment mechanism are inserted from the lower part of the reactor pressure vessel is shown. However, the same effect can be obtained even when the cleaning tool and the wastewater treatment mechanism are inserted from the upper part of the reactor pressure vessel. Can be

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, the activated clad adhering to the stretch tube or the pump nozzle of the internal pump in the state which was installed in the lower part of the reactor pressure vessel can be quickly and reliably washed.

[Brief description of the drawings]

1 to 5 are cross-sectional views showing a cleaning apparatus for an internal pump which is a different embodiment of the present invention, and FIG. 6 is a cross-sectional view of an improved boiling water reactor (ABWR).
The figure is an explanatory view of the configuration of an internal pump installed in the lower mirror section of the reactor pressure vessel. 1 ... Reactor pressure vessel, 8 ... Internal pump, 17
…… Pump nozzle, 18 …… Stretch tube, 20 ……
Pump casing, 28 cleaning brush, 34 drainage treatment mechanism, 35 internal pump cleaning device, 42 water spray nozzle, 46 ultrasonic cleaning tool.

────────────────────────────────────────────────── (5) References JP-A-58-42997 (JP, A) JP-A-58-42998 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G21F 9/28 G21C 19/02

Claims (5)

(57) [Claims] 1. A cleaning device for remotely cleaning a stretch tube or a pump nozzle of an internal pump provided at a lower part of a reactor pressure vessel, wherein the cleaning apparatus is detachably attached to a portion of the internal pump casing outside the pressure vessel. A holding member that is attached to the inside and seals the inside, a cleaning tool held by the holding member and inserted into the internal pump casing to clean the stretch tube or the nozzle, and flush water to the outside of the internal pump casing. A cleaning device for an internal pump, comprising: a discharging means for discharging. 2. The cleaning device for an internal pump according to claim 1, wherein the cleaning tool includes a brush for rubbing the stretch tube or the pump nozzle, and a driving unit for driving the brush. 3. A cleaning device for an internal pump according to claim 1, wherein the cleaning tool includes a watering nozzle for watering the stretch tube or the pump nozzle, and a water supply unit for supplying water to the watering nozzle. . 4. The internal pump cleaning apparatus according to claim 1, wherein the cleaning tool includes an ultrasonic oscillator and an ultrasonic oscillator. 5. The cleaning apparatus according to claim 1, wherein a step of separating the impeller from a drive shaft of the internal pump from an upper portion of the reactor pressure vessel, and a step of removing a pump component in the internal pump casing to the outside. And a step of driving the washing device to wash the stretch tube or the pump nozzle, and a step of discharging washing water to the outside of the internal pump casing. Cleaning method.