JPS6051074B2 - Shaft seal packing replacement device installed in nuclear reactor fuel exchange machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shaft sealing packing installed in a nuclear reactor fuel exchanger, which is moved from the fuel exchanger to an airtight container by remote control while being isolated from the outside, and is cleaned here. The purpose of the present invention is to provide a new shaft seal packing replacement device that allows operations such as maintenance and inspection of shaft seal packings and replacement of packing members to be carried out safely without exposing workers to radiation. .

In fast breeder reactors that use sodium as the primary coolant, in those that perform fuel exchange using the underplug method, the gripper of the fuel exchanger is inserted into the reactor through a rotating plug in the reactor vessel to perform the fuel exchange operation.

As such a fuel exchanger, a configuration has already been proposed in which the exchanger is equipped with a shaft seal packing so as to form a pressure boundary with respect to the inside of the furnace at the location where the gripper passes through the sealing valve, without housing the entire exchanger in an airtight container. ing. The structure of such a fuel exchanger is shown in FIG. In the figure, 1 is a rotary plug of the furnace vessel, 2 is a door valve as a damping valve provided above the through hole of the rotary plug 1, 3 is sodium as a primary coolant, and 4 is sealed in the upper space. Cover gas such as argon gas. The main components of the fuel exchanger 5 include a door valve 6 that is connected to the top of the door valve 2 at the lower end, a gripper 7, and a gripper lifting device 8, and the gripper 7 extends through the door valve 6. A shaft sealing sleeve 8 is provided in communication with the upper part of the door valve 6 at a location where the shaft sealing sleeve 8 is connected.
A shaft sealing packing 9 is provided inside, and this shaft sealing packing 9 forms a pressure boundary at the penetration point of the gripper 7. The operation of the fuel exchanger 5 is well known and will not be described here. The detailed structure of such a conventional shaft sealing packing is shown in FIG. The shaft seal packing 9 includes a shaft seal housing 11 that is airtightly connected to the upper end of the outer cylinder 8 via a flange 10, and a pressure seal that is attached to the upper, middle, and lower parts of the inner surface of the housing 11 along the axial direction. A packing member 12 for preventing cover gas leakage forming a boundary, a brush member 13 made of a braided body of corrosion-resistant metal for cleaning sodium attached to the outer periphery of the gripper 7, and a scraper 14 for scraping off the sodium. Configured with the necessary features. As mentioned above, the shaft sealing packing 9 of a fuel exchanger applied to a sodium reactor is subject to rapid deterioration in packing performance due to sodium vapor adhering to it during operation and sodium accumulation occurring.
Relatively frequent maintenance and inspection or replacement of each packing member is required.

However, as is clear from the structure shown in Figure 2, conventionally,
To replace the shaft seal packing, the shaft seal packing 9 must be pulled upward from the outer cylinder 8, and this work must be done manually. In this case, as mentioned above, since a large amount of radioactive sodium adheres to the shaft sealing packing 9, there is a risk that the operator may be exposed to radiation, which poses a safety problem. The present invention was conceived in view of this point, and when replacing the shaft seal packing,
A new shaft seal packing that can be safely removed and isolated from the fuel exchanger by remote control by cleverly using the gripper of the fuel exchanger without the need for workers to touch it directly, and furthermore, can pre-purify the sodium in this state. DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be explained in detail below based on the illustrated embodiments.

First, according to the present invention, the shaft seal packing is constructed as a cassette-type structure that is installed in the shaft seal outer cylinder 8 so that it can be pulled out downwardly as shown by arrow A, as shown in FIG. That is, the shaft seal housing 11 has a cylindrical shape, and is provided with an O-ring 15 on its outer periphery so as to be in close contact with the outer cylinder 8 in an airtight manner. This housing 11 is fixedly supported via a fixing bolt 17 screwed through the upper cover 16 of the outer cylinder 8, and by removing this fixing bolt 17, it can be pulled out downward. Note that 18 is a guide ring for the gripper. Furthermore, an engaging pawl 19 is provided at the lower end of the housing 11 and extends downward. 19a indicates a claw portion at the tip.

The engaging claw 19 is engaged with a replacement adapter on the shaft seal packing replacement device side, as will be described later in operation. On the other hand, the shaft seal packing replacement device is constructed as shown in Fig. 4. In the figure, a door valve 21 as a sealing valve is connected to the door valve 6 of the fuel exchanger at the upper part of the pedestal 20, and an airtight container 22 for storing the shaft seal packing is suspended below and connected in communication with the door valve 21. It is installed lower. In addition, there are piping 2 at the top and bottom of the sealed container 22.
3, 24, and 25 are open. Of these, piping 23,
A cleaning system consisting of a cleaning liquid supply source 26 for cleaning sodium adhering to the shaft seal packing 9 and a cleaning waste liquid processing section 27 is connected to the pipe 24, and an inert gas source 28 for gas replacement is connected to the piping 25. Connected. In addition, 29 is each piping 23,
There are on-off valves connected to 24 and 25. Furthermore, airtight container 22
A replacement adapter 32 is attached to a mounting seat 30 via a ball latch mechanism 31 at the inner lower part of the mounting seat 30 . This adapter 32 has a handling head 33 at the top that corresponds to the gripper claws of the fuel exchanger, and an engagement head 33 on the side that has a swinging claw structure that engages the above-mentioned engagement claw 19 provided on the shaft seal packing 9. A mechanism 34 is installed. The ball latch mechanism 31 is configured to be engaged and disengaged by rotating a handle 36 provided on an operating shaft 35 that penetrates the closed container 22 and extends outward. Next, a shaft seal packing replacement operation using the replacement device having the above configuration will be explained.

First, prior to work, the inner space of the exchanger is replaced with an inert gas. In this state, as shown in FIG. 5, the fuel exchanger 5 is connected above the shaft seal packing exchanger, and the door valves 6 and 21 are opened. From this connected state, the gripper 7 of the fuel exchanger 5 is lowered to grasp the replacement adapter 32 inside the airtight container 22, and then the adapter 32 is attached to the fuel exchanger 5.
into the outer cylinder 8. Note that the ball latch mechanism 31 that holds the adapter 32 is released in advance. When the adapter 32 reaches the engagement claw 19 of the shaft seal packing 9, the claw 3
4 fits into the claw 19 and the two are engaged. Here, if you remove the fixing bolt 17 that fixes the shaft seal packing 9 to the outer cylinder 8 and lower the gripper 7 again, the shaft seal packing 9
is pulled out together with the adapter 32 downward as shown by arrow A, passes through the door valves 6 and 21, and is drawn into the closed container 22. When the adapter 34 is fitted again into the ball latch mechanism 33 of the mounting seat 32, the ball latch mechanism 31 is locked by operating the handle 36, and only the gripper 7 is raised again. The door valves 6, 21 are then closed and the refueling machine 5 is moved out of the exchanger. Next, the replacement device containing the shaft seal packing 9 is transferred from the furnace container to the maintenance building, where the cleaning liquid supply source 26 and the cleaning system of the waste liquid processing section 27 are connected to the sealed container 22, and the cleaning liquid is supplied to the container 22. supplied within. The shaft seal packing 9 is immersed in a cleaning liquid and is cleaned over time. When the cleaning liquid is discharged and the cleaning process is completed, the door valve 21 is opened, the gripper is lowered from above, and the shaft seal packing 9 is pulled out together with the replacement adapter 31. The shaft sealing packing 9 that has been pulled out is inspected or the packing members 12 and 13
, 14 and O-ring 15 are replaced. In addition, the repaired or inspected shaft seal packing 9 is attached to the fuel exchanger 5 in the reverse order of the removal operation described above. In this case, use a replacement adapter 32'' as shown in Figure 6 as a replacement adapter.
will be replaced by That is, unlike the removal-only adapter 32 shown in FIG. 4, the engagement mechanism is not a swinging claw but a flange piece 34'' that supports the entire shaft sealing packing 9 from below. By using the above-mentioned shaft seal packing replacement device of the present invention, the shaft seal packing 9 installed in the fuel exchanger 5 can be moved into the airtight container 22 of the exchanger by remote control using the gripper 7 of the fuel exchanger. It can be pulled in and further cleaned here.

Moreover, since this series of operations is performed while isolated from the outside air, there is no risk of workers being exposed to radiation due to radioactive sodium scattering, and the shaft seal packing can be replaced safely. As described above, according to the present invention, it is possible to provide a novel shaft seal packing replacement device that simplifies the replacement work and has excellent functions in terms of safety.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the overall structure of the fuel exchange machine to which the present invention is applied in a refueling operation state, FIG. 2 is a cross-sectional view showing the detailed structure of a conventional shaft seal packing, and FIGS. 3 to 6
The figures show an embodiment of the present invention, in which Fig. 3 is a structural cross-sectional view of the shaft seal packing, Fig. 4 is a structural cross-sectional view of the exchange device showing the state in which the shaft seal packing is drawn in and housed, and Fig. 5 is a structural cross-sectional view of the shaft seal packing. FIG. 6, which is a connection state diagram with the exchanger, is a cross-sectional view of the exchange adapter used when attaching the shaft seal packing to the fuel exchanger after inspection and repair. 5: fuel exchanger, 6: fuel exchanger seal valve, 7: gripper, 8: shaft sealing cylinder, 9: shaft sealing packing, 11: shaft sealing housing, 12, 13, 14: packing member, 15:
O-ring, 17: Fixing bolt of shaft seal packing, 19: Engagement claw of shaft seal packing, 20: Frame of replacement device, 21: Shrinkage valve of replacement device, 22: Airtight container, 26, 27: Cleaning system , 28: Inert gas source for gas replacement, 30: Mounting seat, 31: Ball latch mechanism, 32, 32'': Replacement adapter, 33: Handling head, 34, 34'': Engagement mechanism, 36: Operation of ball latch mechanism Handle, A: Pulling direction of the shaft seal packing.

Claims (1)

[Scope of Claims] 1. A fuel exchanger is provided with a sealing valve at the lower end thereof, and is capable of being pulled out downward into a shaft sealing cylinder connected to the upper part of the sealing valve at a portion where the gripper passes through the sealing valve. A sealing valve equipped with a cassette-type shaft sealing packing and provided at the top so as to be connected to the sealing valve of the fuel exchanger, and an airtight container for storing the shaft sealing packing connected in communication with the sealing valve. , the top part of the fuel exchanger is equipped with a handling head for the gripper of the fuel exchanger and an engagement mechanism that engages with the shaft seal packing, and is installed at a lower position in the sealed container so as to be able to be engaged and detached by external operation. For use in a nuclear reactor, characterized in that a shaft seal packing replacement and cleaning device comprising an adapter and a cleaning system coupled to a sealed container and supplying a shaft seal packing cleaning liquid into the sealed container is installed in the fuel exchange machine. A shaft seal packing replacement device installed in a fuel exchange machine. 2. The exchange device according to claim 1, which includes: a cylindrical shaft seal housing in which the shaft seal packing is bolted to the shaft seal outer cylinder; and a shaft seal packing member provided on the inner periphery of the shaft seal housing. A shaft seal packing installed in a nuclear reactor fuel exchanger, characterized in that it is configured to further include an engagement claw for an engagement mechanism of an exchange adapter extending downward from the shaft seal housing. exchange device. 3. In the exchange device according to claim 1, the exchange adapter is attached to a mounting seat provided at a lower portion inside the closed container via a ball latch mechanism that is engaged and released by operating a handle outside the closed container. A shaft seal packing replacement device installed in a nuclear reactor fuel exchanger, characterized in that: