JPS6027397B2 - Cleaning device for reactor control rod drive mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides maintenance and inspection work (replacement, disassembly, cleaning, assembly, and ), and particularly relates to a cleaning device for a nuclear reactor control rod drive mechanism that cleans the inner wall of a CRD outer tube and the outer wall of a cylinder tube.

FIG. 1 shows the general structure of a CRD. CRD body 10
A mounting portion 10b of the CRD main body and a hollow cylindrical outer cylinder 10a integrally protruding from the mounting portion 10b.
A hollow cylindrical cylinder tube 12 faces the inner wall of the outer tube 10a with a hollow cylindrical gap 15 in between and integrally projects from the mounting portion 10b.
It consists of Inside the mounting portion 10b, there are a driving water passage 14 and a driving water inlet 14b that communicate with the inside of the cylinder tube 12, and an index tube driving water passage 1.
4c, and a passage 14a branching from this passage 14 and communicating with the gap 15 are formed, respectively. A two-stage cylindrical piston tube 7 is inserted into the cylinder tube 12 and is inserted into a hollow cylindrical gap formed between the outer wall of the small cylindrical portion of the piston tube 7 and the inner wall of the silling tube 12. is drive piston 5
is slidably inserted. The drive piston 5 has a structure not clearly shown in the diagram.
A continuous hollow cylindrical index tube 8 is engaged. A spat 1 is attached to the tip of the index tube 8. A stop piston 4 inserted into the tip of the piston tube 7 is loosely inserted into the index tube 8, and an inner filter 2 that comes into contact with the inner wall of the index tube 8 is attached to the top of the stop piston 4. It will be worn. A collector assembly 11 and a guide cap 6 are attached to the gap formed between the index tube 8 and the outer tube 10a, and a hollow cylindrical outer filter 3 is attached to the guide cap 6. CRD consisting of the above configuration
In order to clean the CRD, the CRD is first taken out from inside the reactor pressure vessel, transported to the CRD repair room, and dismantled. Next, the disassembly procedure will be explained with reference to FIG. First, outer filter 3,
Remove the spout 1, inner filter 2, and strainer 13 using tongs or similar tools. Next, ring flange 9
Then, remove the index tube 8, drive piston 5, piston tube 7, and stop piston 4 as one unit, and then remove the guide cap 6 and collector assembly 11 from the outer tube 10a. The engagement with the index tube piston 5 is released, the piston tube 7 is pulled out from the index tube 8, and then the drive piston 5 and the stop piston 4 are removed from the piston tube 7. As described above, the CRD is disassembled into individual component parts. Outer tube 10a
Since the cylinder tube 12 and the cylinder tube 12 are integrally constructed as described above, and the gap 15 is a narrow gap, it is difficult to completely clean the gap 15. On the other hand, this gap 15 is necessary for the function of the CRD, and the outer tube 10a and the cylinder tube must be integrally formed in terms of strength and structure. On the other hand, contamination occurs in the gap 15 due to the introduction of the working medium of the CRD.
Regular thorough cleaning is required. However, cleaning by hand is not sufficient and the work efficiency is extremely low. In addition, CRDs have a drawback in that they have a large amount of radiation contamination, which causes safety management problems due to the large amount of radiation exposure during manual cleaning. The present invention was created in order to eliminate the above-mentioned drawbacks, and its purpose is to semi-automatically clean the inner wall of the outer tube and the outer wall of the cylinder tube, improve work efficiency, and radiation exposure of workers. An object of the present invention is to provide a cleaning device for a nuclear reactor control shank drive mechanism suitable for reducing radiation exposure.

The cleaning device of the present invention is a reactor control shank drive mechanism in which the internal drive mechanism is removed and the outer tube inner wall A and the cylinder in the reactor control shank drive mechanism have a main body attachment part 10b, an outer tube 10a attached to the upper part, and a cylinder tube 12. This device cleans the outer tube wall B, and is installed at the inlet 14b of the drive water passage 14, which is perforated in the main body attachment part 10b and communicates with the gap 15 between the outer tube 10a and the cylinder tube 12. A high-pressure hose 25 for water supply, a plug 21 that branches from the passage 14 and closes the outlet 14d of the index tube drive water passage 14c, and a drain adapter for discharging cleaning water to the outside from the outlet 15a of the gap 15. 26 and a drain hose 27 connected to the drain adapter 26 as the main components.

Embodiments of the present invention will be described below based on the drawings.

In FIG. 2, an outlet 14d of a passage 14c that fits inside the cylinder tube 12 of the passage 14 formed in the mounting portion 1ob of the CRD main body 10 is connected to the cylinder tube 12.
It is closed by a plug 21 inserted into the hole. ○Ring 2
2 is fitted with iron in a groove formed in the plug 21, and presses against the inner wall of the cylinder tube 12 to prevent leakage of high pressure water from the outlet 14d. An outlet 15a of a gap 15 formed between the outer tube 10a and the cylinder tube 12 is closed by a stepped drain adapter 26 inserted into the outer tube 10a and the cylinder tube 12, respectively. The O-ring 22 is for leak prevention.

A drain hose 27 is connected to the drain adapter 26 through a self-sealing coupling 24, and the drain hose 27 is connected to the passage 3 formed in the drain adapter 26.
0 through the gap 15 is suitable. The drain adapter 26 is screwed onto the outer cylinder 10a using a bolt hole 28 formed in the outer cylinder 10a.
On the other hand, at the position of the high pressure hose attachment part 29 of the attachment part 10,
A high-pressure hose 25 for supplying cleaning water is attached via an O-ring gasket 23 and a self-sealing coupling 24, and this high-pressure hose 25 communicates with the passage 14 formed in the attachment portion 10b. The high-pressure hose attachment part 29 has a structure as shown in FIG. 3, and has a bolt hole 41 for screwing the CRD main body 10 to a CRD housing (not shown). Therefore, the bolt holes 41 can be used to attach the high pressure hose 25 and the like to the attachment portion 10b. Now, the cleaning water is introduced into the passage 14 from the high-pressure hose 25 through the inlet 14b provided in the attachment part 10b, but since the outlet 14d is blocked by the plug 21, the cleaning water enters the inside of the cylinder tube 12. does not enter, but only enters the gap 15 via the pilgrimage 14a.

Since the passage area of the passage 30 formed in the drain adapter 26 is narrow, the cleaning water injected into the gap 15 passes through the passage 30 and flows out from the drain hose 27 while its outflow is restricted. The contaminated portion within the gap 15 is cleaned by the flow rate and high pressure of the cleaning water and the above-mentioned outflow restriction means. Note that the cleaning work can be performed by simply draining high-pressure water after the plug 21, drain hose 27, etc. are attached to the CRD main body 10, and no special manual work is required. Furthermore, since the drain adapter 26, high-pressure hose, etc. are all attached using existing holes, no special measures are required for attaching them, and there is no possibility of damaging the CRD body. In the above embodiment, the cleaning device was used to clean the inner wall A of the outer tube and the outer wall B of the cylinder tube, but the cleaning device consisting of an adapter with a sealed structure having the same function was used to clean the outer filter 3, strainer 13, etc. of the CRD exposed to radiation. Of course, it can also be applied to cleaning areas with a large amount of water. As is clear from the above explanation, the cleaning device of the present invention can completely clean the gap in the CRD body, and since there is little cleaning work with the RD body coming into contact with the straight twill, radiation exposure is reduced. , complete. Furthermore, since the cleaning work is semi-automatic, work efficiency can be significantly improved compared to manual cleaning.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a CRD, FIG. 2 is a sectional view showing a cleaning device as an embodiment of the present invention, and FIG.
FIG. 3 is a plan view showing a high-pressure hose attachment part of the CRO main body. 1... Spat, 2... Inner filter, 3... Outer filter, 4... Stop piston, 5... Drive piston, 6... Guide cap, 7... Piston tube, 8... Index tube, 9... Ring flange, 10... CRD body, 10a... Outer tube, 10b.・．． ...CRD main body mounting part, 1 1
...Collet assembly, 12... Schilling tube, 13... Strainer, 14... Passage, 14a
...Passage, 15...Gap, 21...
Plug, 22...○Ring, 23...○Ring gasket, 24...Self-sealing coupling, 25...High pressure hose, 26...Drain adapter, 2
7...Drain hose, 28...Bolt hole, 29...
...High pressure hose attachment part, 30...Passage. Winter/Kata Z map 3

Claims (1)

[Claims] 1. A device for cleaning the inner wall of the outer tube and the outer wall of the cylinder tube in a reactor control rod drive mechanism in which the internal drive mechanism has been removed and has a main body attachment part 10b, an outer tube 10a attached to the upper part, and a cylinder tube 12. The outer tube 10a and the cylinder tube 12 are bored in the main body mounting portion 10b.
Inlet 14 of driving water passage 14 communicating with gap 15 between
A high-pressure hose 25 for supplying cleaning water is attached to the index tube drive water passage 1 and branches from the passage 14.
The main components include a plug 21 for closing the outlet 14d of the gap 15, a drain adapter 26 for discharging the cleaning water to the outside from the outlet 15a of the gap 15, and a drain hose 27 connected to the drain adapter 26. A cleaning device for a nuclear reactor control rod drive mechanism, characterized in that: