JPS6020471Y2 - Reactor pressure vessel flange stud hole cleaning device - Google Patents

Description

[Detailed description of the invention] This invention relates to a device that can automatically and efficiently clean the inside of the flange stud hole for tightening the upper lid of a reactor pressure vessel. This invention relates to a flange stud hole cleaning device for a furnace pressure vessel.

Generally, the pressure vessel of a nuclear reactor has an openable and closable upper cover, and the upper cover is removed during periodic inspections of the reactor, fuel replacement, and the like.

That is, in the reactor pressure vessel 1 shown in FIG. 1, a stud hole 3 is provided in the flange 2a of the vessel body 2 as shown in FIG. The stud bolt hole 6 of the upper lid 5 is fitted, and in this state, the upper lid 5 is fastened and fixed to the 7 flange 2a of the container body 2 by the nut 7 screwed onto the stud bolt 4.

The reactor is operated in such a state, but during periodic inspection or fuel replacement of the reactor, the upper cover 5 of the pressure vessel 1 is removed as shown in Fig. The stud bolt 4 also needs to be removed for inspection or other reasons during the service period.

By the way, after the upper M5 is removed, the reactor internals 8 containing spent fuel etc. are extracted from the pressure vessel 1 as shown in FIG. 4, but this type of reactor internals 8 has extremely high radioactivity. In order to prevent this, the reactor well 9 is filled with water and the reactor is moved in the water.

In this case, since the reactor internal structure 8 is lifted up by an overhead crane and moved laterally in the water near the opening of the pressure vessel 1, the stud bolts 4 that interfere with the lateral movement have already been removed.

As a result, the inside of the flange stud hole 3 of the pressure vessel 1 becomes flooded with water and rust occurs.

Therefore, it is conceivable to plug the inside of the stud hole 3 with a separate plug to prevent water ingress, but even in this case, since periodic reactor inspections are carried out over a long period of time, the stud hole 3 may be closed during that time. Rust forms inside.

For this reason, after periodic inspection or fuel replacement, the reactor internals 8
When resetting the reactor well 9, draining the water in the reactor well 9, and reinstalling the stud bolt 4 into the stud hole 3, it is necessary to clean the inside of the stud hole 3.

Conventionally, the cleaning work has been performed manually, which has caused various problems such as poor workability and relatively high radiation exposure for workers.

In other words, this type of stud hole 3 has a large hole diameter, and since the worker must carry a wire brush while wearing a full-body mask to prevent exposure to radiation, his/her movements are restricted and the work area is large. This kind of work requires a considerable amount of effort and time, and therefore the workability is extremely poor.In particular, it is impossible to evenly and uniformly clean the entire surface of the threaded part inside the stud 3 by the above-mentioned manual work. Met.

In addition, rawhide or rust or foreign matter attached to the threaded part of the stud hole mentioned above is radioactive, so radioactive dust will be thrown up during cleaning, and even if the worker is wearing a mask, the amount of radiation exposure will be high. There were problems such as the relatively high price.

Therefore, in order to solve the above-mentioned problems, the present applicant has developed a device that can automatically and mechanically clean the inside of the flange stud hole of a reactor pressure vessel (Utility Application No. 54-133052).
However, this invention was devised to further improve this.

The purpose of this invention is to enable the inside of the flange stud hole of a reactor pressure vessel to be brushed and cleaned uniformly and efficiently over the entire surface by automatic mechanical means, and in particular, when the brush is inserted into or removed from the flange stud hole, the inside of the flange stud hole is brushed cleanly. By preventing sliding contact and thereby preventing the removed dust such as rust or foreign matter adhering to the brush from falling onto the stud Omukai, the collection efficiency of the removed dust is improved and the stud Omukai is reliably cleaned. To provide a flange stud hole cleaning device for a nuclear reactor pressure vessel as described above.

A preferred embodiment of this invention will be described below with reference to FIGS. 5 to 7.

In the figure, reference numeral 10 denotes a central tubular shaft that is inserted into the flange stud hole 3 of the reactor pressure vessel 1 and becomes a dust suction pipe. They are connected to each other and integrally have a dust suction disk 12 at the lower end.

The dust suction disk 12 has an inverted dish shape and is seated on the bottom wall surface inside the stud hole 3, and has a suction cutout hole 13 at the lower end of the peripheral wall.
In addition, a communication hole 14 with the central tubular shaft 10 is provided at the center.

Further, the dust suction disk 12 integrally includes an upright cylindrical portion 16 that forms a spring chamber 15 with the lower outer circumferential wall of the central tubular shaft 10, and an annular pedestal 17 on the peripheral edge side of the upper surface.

On the other hand, an elevating cylindrical shaft 18 is slidably inserted into the outer periphery of the central tubular shaft 10, with the upper end of the upright cylindrical portion 16 being the lowering limit point, and this elevating cylindrical shaft 18 is pushed into the spring chamber 15. It is constantly urged upward by a spring 19 housed as upward urging means.

A cylindrical rotating shaft 23 is fitted onto the outer periphery of the elevating cylindrical shaft 18 via upper and lower bearings 21 and 22 held at a predetermined interval by a cylindrical bearing spacer 20.

This cylindrical rotating shaft 23 has a driven gear 24 integrally at its upper end, and this driven gear 24 meshes with a main driving gear 25 fitted to the output shaft of an air motor 26, so that the air motor 26 rotates the cylindrical shape. The shaft 23 is rotatably driven.

Cylindrical division bodies 281 to 28. are held coaxially so that they can expand and contract in the radial direction.

Cylindrical division body 28. ~28. In the case of the illustrated example, as shown in Fig. 7, it consists of an arc-shaped plate divided into four parts in the radial direction from the center of the cylinder, and has a mounting structure in which the side edges of adjacent plates are slid into contact with each other in a staggered manner. In addition, inward flanges 28a to 28d are curved at the lower end of each.

Furthermore, each cylindrical divided body 28□-28. A brush 29 is installed on the outer peripheral wall surface of the brush.

and cylindrical divided bodies 281 to 28. is always supported via each inward flange 28a to 28d by a roller 30 that is pivotally supported on the annular frame 17 of the dust suction plate 12, and horizontally expands outward in the radial direction when the elevating cylindrical shaft 18 descends under this condition. , and moves linearly inward in the radial direction when rising, and a detailed explanation of its operation will be described later.

On the other hand, the motor 26 serving as a driving means for the cylindrical rotating shaft 23 is installed in a gear case 31.
An air supply hole 32 is provided in the bottom wall of the flange stud hole 3, which opens at the upper end of the brush 29 when the brush 29 is in the maximum expanded position in pressure contact with the tap surface in the flange stud hole 3.

An exhaust pipe P of the air motor 26 is communicated with the air supply hole 32 via a filter F.
After the exhaust gas is filtered, it is forcibly supplied to a gas flow path 33 formed between the tapped surface of the flange stud hole 3 and the cylindrical divided bodies 281 to 284.

Further, a gear case 3 is provided on the upper end side of the central tubular shaft 10.
1 and a driven gear 24, an elevating and lowering operation means 34 is provided for moving the elevating and lowering cylindrical shaft 18 and the cylindrical rotating shaft 23 up and down.

In the illustrated example, this lifting/lowering operation means 34 is a central tubular shaft 1
The cam 34a is rotatably supported vertically via a bracket on the gear case 31 and has a cam surface joined to the upper surface of the gear case 31, and a contact lever 34b is integrally connected to the base end of the cam 34a. There is.

Next, the operation of the above embodiment will be explained.

First, in the cleaning device having the above structure inserted into the flange stud hole 3 of the reactor pressure vessel 1, the long side portion of the cam 34a of the lifting operation means 34 is displaced upward from a substantially horizontal position. , a gear case 31, a cylindrical rotating shaft 23 and an elevating cylindrical shaft 18 linked to this gear case 31 via a driven gear 24, each of which is connected to a spring 1.
5, it is in the upwardly biased state.

Therefore, in this state, the pivot 27a on the cylindrical rotation shaft 23 side of each link 27 is lifted higher than the pivot 27b on the opposite end, and each link 27 is inclined, so that the cylindrical divided bodies 281 to 28 ．． is contracted radially inward so that the brush 29 is held within the diameter of the dust suction disc 12 and does not come into contact with the tapped surface in the flange stud hole 3.

In this state, the brush 29 side of the cleaning device is inserted into the flange stud hole 3, and the dust suction disk 12 is supported on the inner bottom surface thereof.

The state at this time is shown in FIG.

Next, when the operating lever 34b is used to turn the long diameter end of the cam 34a to press it against the upper surface of the gear case 31, the gear case 31, the cylindrical rotating shaft 23, the elevating cylindrical shaft 1
8 is lowered against the spring 15 in a unitized state.

During the descent, each link 27 follows and rotates as horizontally as possible, so that the cylindrical divided bodies 281 to 28. teeth,
Each of the lower end flanges 28a to 28d slides on the roller 30 and expands radially outward.

Thus, the brush 29 is pressed into contact with the tapped surface within the flange stud hole 3 as shown in FIG. 5, so that the cleaning device is ready for use.

Therefore, when the air motor 26 is started, both the master and slave gears 2
The cylindrical rotating shaft 23 is rotationally driven through the link 27, and the rotational force is transmitted to the cylindrical divided bodies 28□ to 284 through the link 27, so that the brush 29 brushes the tap surface in the flange stud hole 3. Ru.

During brushing, the exhaust air from the air motor 26 is forcibly sent to the air hole 32 of the gear case 31 through the filter F through the exhaust pipe P.
Pressure air is blown onto the brush 29 from the brush 29.

This pressure air flows between the cylindrical divided bodies 281 to 284 and the stud holes 3.
The air flows toward the inside of the dust suction cup 12 through the gas flow path 33 formed between the tap surface of the brush 29 and the brush 29 .

At this time, on the one hand, since the dust collector 11 is sucking the inside of the central tubular shaft 10 and the inside of the dust suction disk 12, the flow rate of the pressurized air passing through the gas flow path 33 is accelerated, and the rust, foreign matter, etc. removed by the brush 29 is entrains dust.

Then, the pressurized air entrained with dust flows into the dust suction disc 12 through its suction cutout hole 13, and then passes through the central tubular shaft 10 and is sucked into the dust collector 11.

After cleaning the inside of the stud hole 3 as described above, the air motor 26 and the dust collector 11 are stopped.

Next, the cam 34a is rotated to the sideways position shown in FIG. 6 by the operating lever 34b.

Then, the rotating shaft 23 is pushed up by the spring 15 via the elevating cylindrical shaft 18, and the link 27 is tilted accordingly, so that the cylindrical divided bodies 281 to 284 are moved up and down by the rollers 3.
0, horizontally moves radially inward and contracts.

As a result, the brush 29 moves into the stud hole 3 away from the tap surface, and by removing the cleaning device in this state, the brush 29 can be pulled out without contacting the tap surface inside the stud hole 3.

Therefore, even if dust such as rust or foreign matter is attached to the brush 29, the dust and the brush can be collected from inside the stud hole 3.

In addition, in the above embodiment, the cylindrical divided bodies 281 to 284
It is not limited to four parts, but may be divided into any number of parts, and the side edges of each part may be connected to each other by an elastic member such as a bellows.

Furthermore, the elevating/lowering operation means 34 need not be limited to the cam lever, and may be any other mechanism or automatic mechanical means.

Additionally, the drive source for the cylindrical rotating shaft 23 is not limited to the air motor 26, but may be any other electric motor, etc. In that case, the dust removed by brushing only needs to be sucked and collected by the dust collector 11, so the above implementation is not necessary. The same effect as in the example can be obtained.

In summary, this invention has the following excellent effects.

(1) The tap surface in the flange stud hole of the reactor pressure vessel can be efficiently brushed and cleaned automatically and mechanically.

(2) In particular, when the brush is inserted into or removed from the stud hole, it does not come into contact with the inner wall surface of the stud hole, so the insertion and removal work can be done easily, smoothly, and efficiently, and even if dust such as rust or foreign matter does not come into contact with the brush. Even if the brush is attached, the brush can be removed from the stud hole without dropping the dust.

(3) Therefore, the entire surface of the stud hole can be cleaned uniformly and reliably, and subsequent stud bolts can be inserted into the stud hole smoothly.

[Brief explanation of the drawing]

Figures 1 to 3 are partial explanatory diagrams illustrating the reactor pressure vessel in order from the top cover attached state to the top cover removed state and stud bolt detached state, and Fig. 4 is a partial explanatory diagram illustrating the reactor pressure vessel in the order of the top cover installed state, top cover removed state, and stud bolt detached state. The explanatory drawings, FIGS. 5 and 6 are longitudinal sectional views of a cleaning device according to a preferred embodiment of the invention, and FIG. 7 is a sectional view taken along the line X--X of FIG. 6. In the figure, 1 is the reactor pressure vessel, 3 is the flange stud hole,
10 is a central tubular shaft, 11 is a dust collector, 19 is a biasing means, 2
3 is a cylindrical rotating shaft, 27 is a link, 28□ to 284 are cylindrical division bodies, 29 is a brush, and 34 is an elevating operation means.

Claims (1)

[Scope of utility model registration request] A central tubular shaft that is inserted into and removed from the flange stud hole of the reactor pressure vessel and whose shaft hole communicates with the suction part of the dust collector, and a central tubular shaft that is fitted to the outer periphery of the shaft so that it can be raised and lowered and rotated freely and used as a drive source. It is held via an interlocking cylindrical rotation shaft, a biasing means for urging the rotation shaft in the upward direction, and a vertically swingable link that projects in the radial direction of the cylindrical rotation shaft,
A cylindrical divided body that linearly moves radially inward when the cylindrical rotating shaft is raised and expands radially outward when it descends, a brush installed on the outer peripheral wall surface of the cylindrical divided body, and a brush that moves the cylindrical rotating shaft up and down. 1. A flange stud hole cleaning device for a nuclear reactor pressure vessel, comprising a lifting operation means that locks and unlocks the link in a lowered position where the link is in a substantially horizontal state.