JPS6020470Y2 - Reactor pressure vessel flange stud hole cleaning device - Google Patents

Description

[Detailed description of the invention] The present invention is a flange stud of a reactor pressure vessel that can automatically remove rust, foreign matter, etc. that has formed or adhered to the threaded part of the flange stud hole of a reactor pressure vessel. Regarding a hole cleaning device.

As shown in FIG. 1, during reactor operation, the reactor pressure vessel 1 has an upper lid 2 and a trunk 3, with the upper lid flange 2a and the trunk flange 3a facing each other, which are formed at the peripheral edges of the ends of the upper lid 2 and the trunk 3, facing each other. A stud bolt 5 screwed into a flange stud hole 4 on the flange 3a side is inserted into a through hole 6 formed on the upper lid flange 2a side, and is fixed by tightening with a nut 7.

At the time of periodic inspection or fuel replacement, the upper cover 2 is removed by removing the nut 7 as shown in Fig. 2, but after removing M2, the stud bolt 5 is inspected during its use or for other reasons. As shown in Figure 3, the trunk 3
The stud bolt 5 may be removed from the flange stud hole 4.

By the way, since the above-mentioned periodic inspection generally lasts for a long period of time (approximately 3 months), rust will occur in the flange stud hole 4 during that period.

Furthermore, during refueling, as shown in Figure 4, the work is done underwater in order to shield the radioactivity generated when removing the spent fuel and other reactor internals 8 from the pressure vessel 1. However, in this case, the stud bolts 5, which are suspended by the wires 9 and obstruct the movement of the furnace internals 8, are removed, so water enters the flange stud holes 4 and promotes the formation of rust. Ru.

In addition, in order to prevent water from entering the flange stud hole 4 during the above-mentioned underwater work, it is possible to plug the flange stud hole 4, but since the work is for a long period of time, the occurrence of rust cannot be avoided. do not have.

After the periodic inspection or fuel exchange is completed, the stud bolts 5 are reinstalled in the flange stud holes 4 and the upper cover 2 is attached to the body 3. As described above, the threaded portions 4a in the flange stud holes 4 There is a problem in that when the stud bolt 5 is screwed into the flange stud hole 4, so-called galling occurs and the stud bolt 5 does not rotate smoothly because rust, foreign matter, etc. are attached to the raw skin or the flange stud hole 4.

Conventionally, when screwing in, a worker used a wire brush to clean the inside of the flange stud hole 4 in advance, but the flange stud hole 4 was large and the threaded part 4a
Due to the large area, it took a considerable amount of time to complete the work.

In addition, since the workers work while wearing full-face masks to avoid exposure to radiation, the work efficiency is extremely poor, and since it is a manual process, it is difficult to clean the entire screw surface evenly. was extremely difficult.

Furthermore, raw skin or other foreign substances attached to the threaded portion of the flange stud hole 4 are radioactive, and therefore, radioactive dust will be thrown into the air during cleaning with a wire brush, making it dangerous for workers. It was considered a health management problem.

The present invention was devised by focusing on the above-mentioned circumstances, and its purpose is to completely and quickly remove rust and foreign matter adhering to the flange stud Omukai of a reactor pressure vessel so that the threaded surface is uniform over the entire surface. To provide a flange stud hole cleaning device for a nuclear reactor pressure vessel, which can clean the removed dust and reliably recover the removed dust, thereby improving work efficiency and safety and saving labor.

A preferred embodiment of the present invention will be described below in detail with reference to FIG.

In the figure, 10 is a hollow cylindrical body with a circular cross section that is detachably inserted into a flange stud hole (hereinafter referred to as stud hole) 4 of the reactor pressure vessel 1, and a brush 11 is removed from the outer peripheral wall 10a. They are installed in a spiral arrangement along the axial direction to exhibit rust and dust removal effects.

The tip 10b of the hollow cylindrical body 10 is formed into a conical shape along the bottom surface of the stud hole 4, and a brush 11 similar to the outer peripheral wall 10a is implanted therein.

The brush 11 is made of synthetic resin bristles with a powdered grindstone attached, and the tip of the brush 11 comes into sliding contact with the threaded portion 4a in the stud hole 4 or the bottom surface.

On the other hand, the outer peripheral wall 10a and the tip portion 10b of the hollow cylindrical body 10
A plurality of suction holes 12 are provided in the hollow cylinder 10 so that the dust removed by the brush 11 is introduced into the hollow cylinder 10.

A flange portion 10c is formed at the base end portion of the hollow cylindrical body 10 configured as described above, and this flange portion 10c
The hollow cylindrical body 10 is removably connected to the support shaft 13 by connecting it to a flange portion 13a formed at the lower end of the support shaft 13, which will be described later, using bolts or the like.

This support shaft 13 is a hollow rotary shaft formed in a funnel shape so that its lower end has the same diameter as the hollow cylindrical body 10, and is vertically supported within the casing 14 via bearings 15 and 16. ing.

The casing 14 is formed into a hollow cylindrical shape, and the support shaft 1
3 to support the hollow cylindrical body 10, and when the hollow cylindrical body 10 is inserted into the stud hole 14, it is removably installed on the surface of the body flange 3a and covers the stud hole 4. There is.

Furthermore, two upper and lower supporting members 17.18 are provided at approximately the center of the casing 14, and these supporting members 17.1
8, each of the bearings 15, 16 is mounted on the same axis.

A driven gear 19 is attached to the support shaft 13, and this driven gear 19 is connected via a reduction gear 20.21 to a drive gear 24 attached to the drive shaft of an electric motor 23 as a drive means. The related configuration is described below.

That is, an electric motor 23 with a drive shaft directed downward is attached to the upper wall 14a of the casing 14, and bearings 25 and 26 are connected to the upper wall 14a of the casing 14 and the lower support member 18. The transmission shaft 27 is connected to the upper support member 17
It is installed in a state where it is loosely penetrated.

A reduction gear 20 that meshes with the driven gear 19 of the support shaft 13 is mounted on the lower part of the transmission shaft 27, and a reduction gear 21 that meshes with the drive gear 24 of the electric motor 23 is mounted on the upper part.

Therefore, the rotational driving force of the electric motor 23 is transmitted to the support shaft 13 via the transmission shaft 27, thereby rotationally driving the hollow cylindrical body 10.

On the other hand, a guide tube 2 is attached to the support body 17 to which the bearing 15 is attached.
One end of the guide tube 28 is connected to the support shaft 13 and fixed in a free state, and the other end of the guide tube 28 penetrates the casing 14 and projects to the outside.

A dust collector 2 as a suction means is attached to the guide pipe 28.
9 is connected, and the dust collector 29 is configured to create a negative pressure inside the hollow cylinder 10 via the guide pipe 28 and the support shaft 13.

Therefore, by creating a negative pressure inside the hollow cylindrical body 10, dust such as rust and foreign matter removed in the stud hole 4 is sucked in through the suction hole 12 and is not scattered outside.
will be collected.

Incidentally, reference numeral 30 in the figure is a cushioning material made of urethane or the like attached to the lower edge of the casing 14 in order to uniformly close the surface of the body flange 3a.

Next, the operation of the device of the present invention based on the above configuration will be described.

As mentioned above, the reactor pressure vessel 1 undergoes periodic inspection or fuel replacement, and at this time the upper cover 2 of the pressure vessel 1 is removed.

Along with this, the stud bolt 5 screwed into the stud hole 4 will also be removed, but regular inspections generally require a relatively long period of time, and when changing fuel, the work is done underwater, so the stud bolt 5 screwed into the stud hole 4 is also removed. Since water enters the hole 4, rust and dirt occur on the threaded part 4a inside the stud hole 4 during this time, and the stud bolt 5 will not rotate smoothly when screwed into the stud hole 4 after the inspection is completed. There is a problem.

Therefore, immediately before screwing in the stud bolt 5, the inside of the stud hole 4 (particularly the threaded portion 4a) is cleaned using the device of the present invention.

The procedure will be explained below.

First, insert the hollow cylinder 10 into the stud hole 4, place the casing 14 on the body flange 3a, and then
The dust collector 29 and electric motor 23 connected to are operated.

As a result, negative pressure is created in the hollow cylinder 10 and the suction hole 12
At the same time, the electric motor 2 starts sucking the inside of the stud hole 4.
3 is reduced in speed and transmitted to the support shaft 13 via the reduction gears 21 and 20 of the transmission shaft 27, and the hollow cylinder 10 begins to rotate.

When the hollow cylindrical body 10 rotates, the brush 11 implanted in the outer circumferential wall 10a and the tip 10b brushes the inside of the stud hole 4 such as the threaded part 4a.
Rust, foreign matter, etc. attached to rawhide or the like will be removed.

Rust, foreign matter, etc. that have been wiped off from the threaded portion 4a etc. become dust in the stud hole 4, but these are sucked into the hollow cylindrical body 10 which is under negative pressure through the suction hole 12. The dust is sent to the dust collector 29 via the support shaft 13 and the guide pipe 28,
It will be collected here.

Therefore, even if radioactive foreign matter is attached to the inside of the stud hole 4, it can be collected without scattering to the outside of the stud hole 4, and radioactive air is removed from the stud hole 4 to the outside of the casing 14. Does not cause pollution.

Next, once the inside of the stud hole 4, especially the threaded part 4a, has been completely cleaned, the operation of the electric motor 23 and the dust collector 29 is stopped, and the hollow cylinder 10 is pulled out from inside the stud hole 4.

Threaded portion 4a inside stud hole 4 cleaned in this way
Since there is no rust or foreign matter attached to the stud bolt 5, the stud bolt 5 can be rotated smoothly when screwed into the stud hole 4, and so-called galling does not occur.

As described above, according to the device of the present invention, it is possible to quickly and easily remove raw skin or rust or foreign matter adhering to the inside of the stud hole 4 so that the threaded surface becomes uniform over the entire surface, and
The dust generated at that time is not scattered.

In addition, in the above embodiment, the outer peripheral wall 1 of the hollow cylindrical body 10
Although the brushes 11 are arranged in a spiral along the axial direction of the hollow cylinder 10, the arrangement of the brushes is not limited to this. It is good as long as it has rust removal and dust removal effects.

Further, although the electric motor 23 is used as the driving means, it goes without saying that the driving means may be an air motor or a manual bundle.

Furthermore, a dryer may be disposed inside the casing 14 to dry the inside of the stud hole 4 with the hot air.
This increases the cleaning effect when the inside of the stud hole 4 is in a wet state.

In summary, the present invention provides the following effects.

(1) To clean the flange stud Omukai of the reactor pressure vessel with a hollow cylindrical brush rotated by a driving means,
It is possible to completely and quickly remove raw skin or rust or foreign matter that has adhered to the threaded part of the flange stud hole so that the threaded surface is uniform over the entire surface. The cleaning work that used to be done can be done much more easily, saving labor and improving work efficiency.

(2) It has a casing that covers the flange stud hole, a suction hole is formed in the hollow cylinder extending from the casing, and the inside of the flange stud hole is sucked by the suction means, so that the rust that is removed by the brush is removed. It is possible to reliably collect dust such as foreign objects and other objects without scattering them to the outside, and even if the foreign objects are radioactive, they will not cause air contamination, improving safety. .

(3) Therefore, according to the device of the present invention, the stud bolt can be screwed into the flange stud hole with great ease, the galling of the stud bolt is completely eliminated, and the reliability of the reactor pressure vessel is increased. Moreover, it can contribute to shortening the period of periodic inspection of nuclear power plants.

[Brief explanation of drawings]

The drawings are for explaining the present invention; Fig. 1 is a side view showing the body and upper cover of the reactor pressure vessel tightened with stud bolts, and Fig. 2 is a side view of the upper cover in Fig. 1 with the upper cover removed. 3 is a side view showing the state in which the stud bolts are removed in FIG. FIG. 2 is a longitudinal cross-sectional view showing the configuration of a device according to a preferred embodiment of the present invention. In the figure, 1 is the reactor pressure vessel, 4 is the flange stud hole,
10 is a hollow cylinder, 11 is a brush, 12 is a suction hole, 23 is an electric motor as a driving means, and 29 is a dust collector as a suction means.

Claims (1)

[Scope of utility model registration request] A casing installed on a flange of a reactor pressure vessel so as to cover the flange stud hole; one end rotatably supported within the casing, and the other end extending outside the casing; a hollow cylindrical body inserted into the hole; a brush provided on the outer peripheral wall of the hollow cylindrical body for brushing the inside of the flange stud hole;
a suction hole formed in the hollow cylindrical body for sucking the inside of the flange stud hole; a suction means communicating with the hollow cylindrical body for suctioning and collecting dust removed by the brush through the suction hole; and the hollow cylindrical body. A flange stud hole cleaning device for a nuclear reactor pressure vessel, comprising: a drive means for rotationally driving the flange stud hole of a nuclear reactor pressure vessel.