JPS58129399A - Decontaminating device - 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 The present invention relates to a decontamination device, and particularly to a device for decontaminating the inside of a water chamber of a heat exchanger such as a steam generator in a nuclear power plant.

At nuclear power plants, etc., it is necessary to regularly or temporarily inspect or repair steam generators. However, these steam generators are exposed to radioactive materials, and highly concentrated radioactive deposits accumulate, especially in areas that are in the circulation path of highly radioactive fluids such as light water, which is the primary coolant of the reactor. Because inspection and repair workers tend to be exposed to high levels of radiation in a short period of time, the allowable working time for the same worker is extremely short, and it is difficult to accomplish the desired task. requires the mobilization of a large number of workers.

The present invention has been made with the aim of significantly reducing the amount of radiation exposure during inspection and repair as described above. In other words, decontamination equipment is used to reduce the level of radioactivity in the primary fluid circulation path in heat exchangers such as steam generators, creating an environment where inspection and repair work can be carried out without exposure to radiation. It provides:

Many methods have been proposed in the past to achieve this objective, and among them, the method related to the present invention involves mixing particles with high-pressure fluid and injecting the mixture to deposit particles at a desired location within the fluid circulation path. It is a means of removing and discharging radioactive deposits.

Such techniques are disclosed, for example, in Japanese Patent Publication No. 54-35280 and Japanese Patent Publication No. 55-141700. This can be found as prior art from various publications such as JP-A-56-24599 and others.

The present invention further develops these conventional techniques and performs attachment/detachment, decontamination, self-cleaning, and drainage outside the secondary fluid circulation system, suppressing the exposure of decontamination workers to the minimum level, and moreover, suppressing radiation exposure to high concentrations. Minimize the leakage of pollutants to the outside.

The present invention includes a support that includes a power transmission mechanism, a nozzle arm that is supported at the tip of the support, rotates about its fulcrum, and can be stored in the support, and a heat exchanger ice chamber. It is comprised of a driving part that has a support member that is engaged with a manpole and is configured to be detachable from the support column, and a drainage arm that is tiltable within the water chamber.

The present invention will be explained in detail based on illustrated embodiments.

In FIG. 1, a decontamination device 1 is comprised of a support column 2, a nozzle arm 3, a driving member 4, and a drainage arm 5, and is secured to a manhole 13 of a steam generator 6. The steam generator 6 is surrounded by a shell 7, and a tube sheet 8 is fixed to the inside of the tube sheet 8.A body side space 9 for a secondary fluid, that is, a water supply, is placed above the tube sheet 8, and a primary fluid, that is, a nuclear reactor, is placed below the tube sheet 8. Next coolant ice chamber 1
0 and 11 are formed, and both ends of heat transfer tubes 120 that open into the water chambers 10 and 11 are inserted into the tube plate 8.
protrudes into the space 9 and ψ. Near the lower end of the shell 7,
Manholes 13 and 13' opening to the outside from the water chambers 10fi and 11, respectively, are formed, and a fluid port 14 and a fluid outlet 1 are connected to a secondary fluid circulation pipe (!m not shown).
There are 5. The water chamber 10 and the water chamber 11 are separated from each other by a partition plate 16, and are configured so that the primary fluid flows from the water chamber 10 to the water chamber 1 through the pipe 12. 17 is a locking member for attaching the decontamination device 1 to the manhole 13.

In the actual design, the strut 2 nozzle arm 3, the drive member 4 including the locking member 17, and the drain arm 5 including the electric motor 51 are configured so that they can be easily separated and combined, and can be assembled in a short time at the work site.・Can be decomposed. The steam generator 6 is usually installed in an extremely small space,
Moreover, since the water chambers 10 and 11 to be decontaminated are located at the bottom of the steam generator 6, the long and heavy decontamination device 1 is inserted through the manhole 13.131 in an assembled state. This is because it is often difficult to do so. As shown in FIGS. 5(a), 5(b), and 5(Q), in assembling the nozzle arm 3, which is housed in the support 2, is first inserted into the water chamber 10 through the manhole 13.

At that time, the locking member 17' for temporary fixing is attached to the post 20 at a predetermined position.
7 of manhole 13.
It is temporarily locked on the rung surface 20. Next, after engaging the connecting surface 41 of the drive member 4 and the connecting surface 21 of the support column 2 and fixing them with bolts or other connecting members, the locking member 171 that is engaged with the manhole 13 is removed, and at the same time, the connection surface 21 of the support column 2 is removed.
Remove and remove. The strut 2 and drive member 4 assembled in this way are further inserted into the ice chamber 10, and the drive member 4
The locking member 17 is fixed to the seven rung surface 20 with bolts or other connecting members. The conveying device 18 used for conveying and temporarily fixing the column 2 and conveying, connecting, and fixing the drive member 4 has a lifting function and a traveling function, and has a mounting means that can be used in common for conveying the column 2 and the drive member 4. It is equipped with

Next, as shown in FIG. 5(d), the drain arm 5 is inserted into the water chamber 1o through the locking member 17 and the manhole 13, and then fixed to the locking member 17. In this state, Himuro 10
The water chamber 1o is completely sealed off from the outside air by the locking member 17, and prevents fluid and the like from leaking out of the water chamber 1o. The required high-pressure water hose 61, particle hose 62, drainage hose 63, self-wash port 64, and air hose 65 are connected to the decontamination device 1 assembled in this way, and the electrical wiring M (
(not shown) to complete the installation. When the installation is completed, the nozzle arm 3 is housed in the support column 2, as shown in FIG. 5(d), and the drainage arm 5 is
It is in an upright state along the pillar 2. When the assembly is completed in this way, the conveying device 18 is removed.

Next, the preparation work prior to the start of decontamination work will be explained using FIGS. 2 and 3. First, the nozzle arm 3 is extended from the support 2. This is done by rotating the screw shaft 22 built in the support column 2 by the electric motor 42 built in the drive member 4, and pulling the screw shaft 23 screwed into the female thread at the tip of the screw shaft 22 downward, that is, toward the drive part 4 side. . Accordingly, in order to pull the movable rod 31 pivotally attached to the tip of the screw shaft 23, the nozzle arm 3 rotatably supported at the tip of the support column 2 pivots around the support shaft 24 and is drawn out from the column 2. It will be. The angle formed by the support column 2 and the extended nozzle arm 3 can take various angles depending on the working conditions, but this is controlled by detecting the rotation (direction and @) of the electric motor 42 or the screw shaft 22. Ru. That is, as rotation detection means, a conventional means such as a rotary encoder is provided (not shown).

Next, the drain arm 5 of the cleaning/draining member is bent and tilted by the electric motor 51 via a link mechanism similar to the mechanism for feeding out the column 2 and the nozzle arm 3. The drainage arm 5 is formed in advance to match the curvature of the bottom surface of the ice compartment 1o, and can suck in and discharge the waste water accumulated at the bottom of the ice compartment 1o when it is tilted.

The preparation work is now complete.

1'''≧1 Dyeing work will be explained with reference to Figs. 2, 3, and 4. A high-pressure water hose 61 is connected to a high-pressure water generator (not shown).
At the same time, particles are sent from a particle supply means (not shown) to the particle hose 62, and are sent to the hoses 26 and 27, respectively, through a flow path (not shown) arranged in the drive member 4. .

The high-pressure water and particles are thus mixed in the nozzle 32 and injected as a mixture of high-pressure water and particles. The particles used are water-soluble borax, ice grains, or water-insoluble abrasives. The nozzle 32 is attached to a nozzle block 33, and is driven by a drive means such as a screw shaft 34.
As the 7 moves along the nozzle arm 3, the nozzle 32 moves while spraying a mixture of high pressure water and particles. The screw shaft is driven by an electric motor 43 built into the drive member 4 via the rotating shaft 25. The moving speed of the nozzle 32 is adjusted by controlling the rotation speed of the electric motor 430.

By the way, the tube sheet 8 has a semicircular shape in the water chamber 10, and the entire surface of the semicircular tube sheet 8 must be decontaminated, so the nozzle 32 must be inserted into the entire tube sheet 8. It is necessary to position it relative to the location. For this purpose, the means for rotating the column 20, the means for rotating the nozzle arm 3, and the means for controlling the angle formed by the column 2 and the nozzle arm 3 are used in conjunction. These movements are indicated by arrows B, E and A in FIGS. 2 and 3. The rotating means for imparting the movement indicated by arrow B to the support column 2 is the nozzle arm 3.
This is an electric motor 44 mounted on the drive member 4. That is, the electric motor rotates the column 2 and the drive member 4 as one unit. The drive member 4 includes a fixed part 45 fixed to the seventh rung surface 20 of the manhole 13 by a locking member 17, and a rotating part that passes through the fixed part 45 and is supported by the fixed part 45 via a bearing. By rotating the rotating part 46 with the electric motor 44, the support column 2 is
Rotate as shown by arrow B. The rotation of the nozzle arm 3, indicated by arrow E, determines the injection direction of the nozzle 32. That is, by rotating the support column 20, the nozzle arm 3 and the nozzle 3
2 is inclined with respect to the tube plate 8, which tends to reduce the decontamination effect of the mixture of high-pressure water and particles sprayed from the nozzle 32. Therefore, the nozzle arm 3 is rotated in the direction of arrow E so that the surface formed by the nozzle arm 3 and the nozzle 32 is always maintained perpendicular to the tube plate 8 or in a state close to it. The nozzle arm 3 is driven and driven by an electric motor 42 built into the drive member 4, an electric motor (not shown) attached to the blade, and another rotation shaft (not shown) attached to the rotation shaft 25. Can be controlled. The swinging of the nozzle arm 3 shown by arrow A is due to the movement of the tube plate 8 and the nozzle arm 3 that occurs when the support column 2 rotates during decontamination work, in addition to the movement of the nozzle arm 3 during the installation described above. It has the effect of adjusting the increase or decrease of the interval between the two.

By always maintaining the nozzle arm 3 parallel to the tube plate 8 or in a state close to it, the distance between the nozzle 32 moving along the nozzle arm 3 and the tube plate 8 is kept constant to maintain the best decontamination effect. do.

In this way, each member is appropriately driven as shown by arrows A, B, and E, and the nozzle block 33 is further moved in the direction of the arrows, thereby achieving the desired decontamination effect.

When the decontamination of the tube plate 8 is completed, the support 2 is rotated and the nozzle arm 3 is positioned as shown in FIG. Nozzle 32
The mixture of high-pressure water and particles that is injected from the partition plate 16 is then injected toward the partition plate 16. Then, by skillfully combining the rotation of the column 20 (arrow B), the rotation of the nozzle arm 30 (arrow E), the swinging of the nozzle arm 3 (arrow A), and the movement of the nozzle block 33 (arrow D), the nozzle 32 is moved. Similar to the decontamination of the tubesheet 8 by positioning the water chamber 10
In this step, the semicircular partition plate 16 is also effectively decontaminated.

Now, in the state shown in FIGS. 2 and 3, when the nozzle block 33 moves in the direction of the arrow, the nozzle 3
2 moves in the illustrated direction while spraying a mixture of high-pressure water and particles, the vicinity of the contact point between the tube sheet 8 and the partition plate 16 remains untreated. Therefore, when the nozzle block 33 moves in the direction indicated by the arrow, the nozzle 32 changes direction as indicated by the arrow 1 near the end of movement. That is,
As shown in FIG. 4, the nozzle block 33 includes a nozzle 3
A shaft body 73 that can rotate integrally with the block body 71 is rotatably mounted on the block body 71, and at a predetermined position of the shaft body 73, the gear 7
A reciprocating member 720 mounted on the block body 71 so as to be reciprocally movable engages with the rack 74. In the inner hole 76 of the reciprocating member 72, springs 78 are installed on the left and right sides, sandwiching a bridge member 77 fixed to the block body 71.
．． 79 are provided. In such a structure, by the rotation of the screw shaft 340, the nozzle block 33 moves in the direction indicated by the arrow), that is, toward the end 35 of the nozzle arm 3 on the support shaft 24 side, and the reciprocating member 72 comes into contact with the end portion 35. When the nozzle block 33 further moves, the reciprocating member 72 is pushed against the end portion 35, and this moves against the block body 7.
1 in a direction opposite to the direction of movement of the nozzle block 33 relative to the spring 78. As a result, the gear 75, that is, the shaft body 73 is rotated by the rack 74, and the nozzle 32 is tilted to the left of arrow F. and nozzle 3
The mixture of high-pressure water and particles injected from 2 reaches the contact point between the tube sheet 8 and the partition plate 16. When the nozzle block 33 moves in the opposite direction, the reciprocating member 72 is pushed back by the spring 78 and protrudes in the direction opposite to the direction in which the nozzle block 33 moves. Along with that, rack 7
4 and the gear 75, the shaft body 73 is rotated to open the nozzle 32.
returns to its original position. In this way, the injection direction of the mixture of high-pressure water and particles injected from the nozzle 32 sufficiently reaches the contact point between the tube sheet 8 and the partition plate 16, and there is no untreated residual part, and the tube sheet 8 and the partition plate 16 are completely covered. It is effectively decontaminated.

Next, when decontaminating the spherical part inside the shell 7 of the ice chamber 10,
First, the nozzle block 33 is positioned at the tip or end 36 of the nozzle arm 3 by threading. When the nozzle block 33 is moved.

The reciprocating member 72 comes into contact with the end side and relatively enters the block body 71 against the spring 79, and the relative deviation is converted into rotation of the shaft body 73 by the meshing of the raku 74 and the gear 75. be done. As a result, the nozzle 32 is tilted toward the end portion 36, and the ejection direction is positioned in the same direction as the axis of the nozzle arm 3. Movement of the nozzle 32 during decontamination is as follows:
Movement of nozzle arm 3 in the direction of arrow A and column 2 of arrow B
A combination of directional movements can be used to position the nozzle 32 over the desired area.

In this way, the tube plate 8, the partition plate 16, and the inner surface of the shell 7 are all effectively decontaminated, and at the end of the decontamination, the supply of high-pressure water and particles is stopped.

During the decontamination process, the drainage arm 5 is located at the bottom of the water chamber 10, and is connected to a drainage hose 63 connected to a drainage means such as a drainage pump (not shown). As a result, the waste water accumulated in the ice chamber 10 is sucked in, and the ice chamber 10 is constantly
It is being discharged outside.

When the decontamination process is completed, the decontamination device 1 is removed from the steam generator 6, but before removal, the decontamination device 1 itself must be cleaned. This is because sediments and sewage that fell or were scattered during the decontamination process are attached to the decontamination equipment 1, and if they are removed as is, the result will be the same as the sediments and sewage leaking out from the ice chamber 10. This will hinder the removal work of the dyeing equipment 1. Therefore, before the decontamination equipment-1 is removed, it is cleaned in the water chamber 10 to remove deposits and sewage in order to suppress the release of radioactive materials from the ice chamber 10 as much as possible. Prior to cleaning, the nozzle arm 3 is first stored in the support 2 in the reverse order of the procedure in which it was taken out from the support 2 at the start of work. That is, the screw shaft 22 is rotated by the electric motor 42 built into the drive member 4, and the screw shaft 2
3 is pushed up, and the movement 31 is pushed up by the screw shaft 23 to move the nozzle arm 3 along the arrow A and house it in the support column 2.

Next, the electric motor 51 is driven to raise the drainage arm 5.

Next, send the scuttling water to the self-washing water hose example, and drain the water from the drain arm 5.
Self-sinking water is sprayed toward the column 2 from a self-cleaning nozzle 53 of a self-cleaning vibrator 52, which is attached to the water pipe, to clean the column.

The self-washing water may be general industrial low-pressure water or high-pressure water suitable for decontamination treatment. Regarding the self-washing water pump (not shown), it is possible to install a dedicated pump or to share a high-pressure pump for decontamination processing, and it can be selected as appropriate depending on the equipment. During self-washing, the support 2 is rotated in the direction of arrow B, and self-washing water is evenly sprayed onto the support 2 and the nozzle arm 3. At this point, the supply of self-washing water is stopped, and the drain arm 5 is again tilted in the direction of arrow C to be positioned at the bottom of the ice chamber 10. After that, the waste water accumulated during self-washing is discharged through the drain hose 63,
When the discharge is completed, the drain arm 5 is raised again. If necessary, an air nozzle 54 is provided next to the self-washing nozzle 53, and when the self-washing is finished, compressed air is sent from the air hose 65 and sprayed from the air nozzle 54 to remove water droplets attached to the support column 2 and nozzle arm 3. A configuration may be added to remove the .

After self-washing, all hoses and electrical wiring connected to the decontamination device 1 are removed, and the decontamination device 1 is disassembled and removed.

Decontamination equipment 10 must be disassembled and removed during assembly and insertion.

It can be efficiently performed by reversing the procedure. That is, after the conveyance device 18 is set in the predetermined position of the decontamination device 10, the drainage arm 5 is disengaged from the locking member 17 and removed from the ice chamber 10, and then the locking member 17 is moved to the mantle t, -/l/13. 7
After separating from the rung surface 20, the carrying W device 18 is operated appropriately to remove the decontamination device 1 from the water chamber 10 to the temporary fixing position. After fixing the support column 2 to the flange surface 20 of the manhole 1307 using the temporary locking member 171, the drive unit 4 and the support column 2 are separated from each other at their connecting surfaces 41 and 21, and the drive unit loaded on the conveyance device 18 is removed. The unit 4 is transported to a predetermined location and stored. After the temporarily fixed column 2 is supported by the conveying device 18, the temporary fixing engagement member 171 is detached from the seven rung surface 20, and the column 2 is extracted from the water chamber 10 and is conveyed to a predetermined location and stored. Ru.

The above is the procedure for decontaminating the secondary fluid inlet side ice chamber 10, but it can also be effectively carried out for the water chamber 11 by following the same procedure as for the ice chamber 10.

Since the present invention has the structure and functions as detailed based on the above-mentioned embodiments, workers can always carry out decontamination work outside the water chamber, and are therefore extremely safe without being exposed to high levels of radiation. As all assembly and disassembly of the decontamination equipment is done outside the water chamber, transportation means can be used effectively and the labor required by workers is reduced.The decontamination equipment can be attached and removed without almost touching it. The risk of worker exposure to radiation is extremely small, and the drive unit, which is the main driver, is installed outside the water chamber, making it easy to take into account water. It is possible to use a simple electric motor and achieve highly accurate control, which can have extremely large safety effects.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the relationship between a general nuclear reactor steam generator and the decontamination device according to the present invention, and FIGS. 2 and 3 show the state of the decontamination device that is an embodiment of the present invention. The external view, Figure 4, is a cross-sectional view showing the nozzle direction conversion mechanism extracted, and Figure 5 is an external view.
Figure (→(b)(C)(dl) is an explanatory diagram showing the order of assembly and installation of the decontamination equipment. 1... Decontamination equipment, 2... Support column, 3... Nozzle arm. 4. ... Drive member, 5... Drain arm, 6... Steam generator, 13... Manhole, 17, 17'...
-Locking member. 32... Nozzle, 33... Nozzle block treatment, 2 drawings, 3 flashes

Claims (1)

[Scope of Claim] A decontamination device for a heat exchanger having an ice chamber with a manhole that can be opened and closed, comprising a locking member that is detachably attached to the outer surface of the manhole. a drive member rotatably supported by the locking member and containing a control element including a drive means and a detection means; a support that is detachably engaged with the drive member and projects into the water chamber; and a tip of the support. a nozzle arm that is bendably pivoted to the section and can be stored in the support; a nozzle block that is movably supported by the nozzle arm and reciprocates along the nozzle arm; and a nozzle block that is detachably attached to the locking member. and a drainage/cleaning member including a suction pipe for discharging dirty water in the water chamber and a water sprinkling pipe for spraying washing water onto the support column, the drainage/cleaning member being close to the locking member. A decontamination device characterized by being configured such that the bent portion is flexible.