JPH0449677B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for removing crud as radioactive contaminants deposited in a fuel pool for storing spent fuel provided at a nuclear facility.

When the reactor and pool doors are opened to move the spent fuel from the reactor to the fuel pool, radioactive contaminants from inside the reactor flow into the pool and accumulate on the fuel rack and the bottom of the pool. Moreover, these deposits are highly radioactive, and the conventional treatment method in which the filter container is housed in a lead-shielded drum requires a large number of drums. Not only the amount of drums, but also the amount of radiation exposure to workers, requires a more economical and safer work method. In addition, the differential pressure gauge for determining the amount of crud collected in conventional filter devices installed underwater is attached to the attachment/detachment part of the filter device, so the pointer of the differential pressure gauge of the filter device located at the bottom of water exceeding 10 m is the point in the pool. Due to the movement of the water, it is difficult to see from the water surface, and since the fitting operation is a rotary locking method, the filter device itself rotates with the attaching/detaching device when detaching, making detachment difficult. There were drawbacks such as workers being exposed to radiation due to detachment work.

The present invention solves these drawbacks of the prior art,
It is an object of the present invention to provide a method and apparatus for removing crud that effectively and safely collects crud.

To summarize the configuration for achieving the above objectives, the components of the water circulation system including the cladding,
That is, the nozzle, the solid part separation device, the pump, the filter device, the hose that connects these, and the attachment/detachment device for the hose and filter device are all submerged in water to prevent workers from being exposed to radiation. In addition, there are valves to operate the opening/closing lid of the solids separator, hoses and filter device attachment/detachment devices, pressurization device for operation air, pump switch, filter pressure gauge, and alarm device that indicates the usage limit of the filter, which can be operated on the floor. It is characterized by being installed on the board.

A preferred embodiment of such a configuration will be described below. Figure 1 shows the water circulation system of the device submerged in a fuel pool. Water laden with crud is sucked through nozzle 1 and enters solids separator 3 through hose 2. The solids separator 3 consists of a strainer 4, an air-operated opening/closing lid 6 for dropping accumulated solids into a container 5, and a submersible pump 7 for backwashing to remove solids adsorbed by the strainer 4. ing. The water that has passed through the solid matter separator 3 passes through a submersible pump 8 and is guided by a drain hose 9 to a filter device 10 containing a large number of filters, and the clean water filtered there is discharged into the fuel pool 11 again. be done.

Fig. 2 is an enlarged view of the solid matter separator 3. When the submersible pump 8 is operated, the crud and water sucked in from the hose 2 pass through the strainer 4 and go to the submersible pump 8. There is sediment, and these sediments are sucked out of the nozzle along with the water.
Light and soft materials gradually adhere to the surface of the strainer 4, gradually increasing flow resistance. submersible pump 8
A pressure transmission tube 13 is connected from a pipe 12 connecting the backwash pump 7 and the strainer 4 via valves (not shown) to a vacuum gauge 14 attached to an operation panel (not shown) on the floor. ing. Therefore, as described above, if a large amount of pool bottom sediment adheres to the surface of the strainer 4 and the water flow is obstructed, the degree of attachment can be easily detected by the amplitude of the vacuum gauge 14.

When the pointer of the vacuum gauge 14 begins to swing in this manner, the deposits are removed in the following manner. That is, first, the operation of the submersible pump section 8 is stopped. Next, the air cylinder 16, which is rotatably supported at one end on both sides of the strainer box 15 and rotatably supported at the other end by the opening/closing lid 6 hinged to the lower end of the strainer box 15, is actuated. Open it downward (Figure 2, two-dot chain line),
By activating the backwash pump 7, the deposits adhering to the surface of the strainer 4 are removed by passing water from the opposite direction, that is, from the top to the bottom. Solid container 5
to be accommodated.

When the removal of the adsorbate is completed, the operation of the backwash pump 7 is stopped, and the air cylinder 16 is operated to close the opening/closing lid 6 (solid line position in FIG. 2). This operation makes it possible to efficiently inhale water and crud again.

FIG. 3 shows a device for attaching and detaching the discharge side hose 9 and the filter device 10. A claw 18 for removably attaching an operating rod (not shown) is welded to the short pipe 17 that connects the discharge side hose 9 and the socket 19. When the sleeve 20 is pulled up by driving the air cylinder 21, as shown in FIG. After releasing the locking device, the socket 19 is inserted into the plug 22 which is the water inlet of the filter device 10 using the operating rod attached to the claw 18. After that, when the operating valve of the air cylinder 21 is set to neutral, the sleeve 20 is automatically lowered by the force of the spring 31 built into the locking device, and the ball 32 in the socket 19 is moved to the plug 22.
It fits into the groove 33 of the socket 19 and the plug 2.
2 are connected, the valves in the socket 19 and plug 22 open and the crud and water from the hose 9 flow into the filter device 10.

Conversely, when detaching this attachment/detachment device from the filter device 10, the sleeve 20 is removed from the air cylinder 2.
1 to release the locking device caused by the ball 32 getting stuck in the groove 33 of the plug 22, and then pulling the discharge hose 9, it can be easily removed. When the socket 19 and the plug 22 are separated, valves built in each close the flow paths to each other by spring force. The above-mentioned fitting and removing operations can be easily performed by remote control of an air cylinder, and in the case of fitting, the socket can be simply pushed in using an operating rod.

In addition, a pressure transmission tube 23 from the short pipe 17 connects a pressure gauge 24 and a pressure switch 2 attached to an operation panel on the floor.
5, and when the water pressure in the filter device 10 reaches the working limit pressure of the filter (not shown), a signal is emitted by a signal device such as a buzzer connected to the pressure switch 25. .
Therefore, even when using a filter that tends to cause a sudden increase in pressure near its usage limit, the operator does not need to constantly pay attention to pressure fluctuations in the filter.

FIG. 4 is a system diagram of air for operating the solid matter separator 3 and the attachment/detachment device between the hose and the filter device. The pressurized air coming from the air source 26 is adjusted by the pressure reducing valve 27 to the required pressure plus back pressure, which will be described later, and operates the cylinders through the switching valves 28a and 28b, but the pistons of the cylinders 16 and 21 A pressure higher than the water pressure applied to that cylinder is also transmitted from the pressure reducing valve 29 to the opposite side of the cylinder.
Therefore, water will not enter the air system. Also, when switching the valve, the high pressure air that had been on the operating side comes out to the exhaust side, but this is exhausted by the relief valve built into the pressure reducing valve 29, making it easy to operate the cylinder. can.

The filter device 10 has several dozen cartridge filters inside, and the inflow of water and crud into the device is through a plug 22 that has an internal valve and opens the valve only when the socket is connected, so the filter device itself Even when moving, the internal crud will not leak out. However, since only fresh water filtered by the filter passes through the water outlet of the filter device, an open pipe is installed.

Therefore, according to this crud removal method, even if there is a blockage in the pipe line due to the inflow of solid matter deposited at the bottom of the fuel pool, crud can be accommodated up to the usage limit of the filter while eliminating it. Even if the work is interrupted before the crud is filled to the capacity limit, the above-mentioned hose and filter device attachment/detachment device allows the work to be completed with only the filter device left at the bottom of the fuel pool, and used for the next work. By connecting the discharge side hose again to the filter device that was in the middle, it is possible to accommodate the crud up to the usage limit of the filter.

[Brief explanation of drawings]

FIG. 1 shows a crud removal device according to the present invention submerged in a fuel pool. Figure 2 is an enlarged detailed view of the solids separation device. Figure 3 shows the attachment/detachment device for the discharge side hose and filter device. FIG. 4 is an air system diagram for operating the solid matter separator and the attachment/detachment device between the hose and the filter device. FIG. 5A is an enlarged sectional view of the socket 19 and sleeve 20 in FIG. 3. FIG. 5B is an enlarged sectional view of the plug 22 in FIG. 3. In the figure; 1... Nozzle, 2... Hose, 3
...Solid separation device, 4...Strainer, 5...
(Solid storage) container, 6... Opening/closing lid, 7... Submersible pump (for backwashing), 8... Submersible pump, 9... Discharge side hose, 10... Filter device, 11... Fuel pool, 12 ...Tube, 13...Pressure transmission tube, 14...Vacuum gauge, 15...Strainer box, 1
6...Air cylinder, 17...Short pipe, 18...
Claw, 19...Socket, 20...Sleeve, 21
... Air cylinder, 22 ... Plug, 23 ... Pressure transmission tube, 24 ... Pressure gauge, 25 ... Pressure switch, 26 ... Air source, 27 ... Pressure reducing valve, 2
8a, 28b...Switching valve, 29...Pressure reducing valve, 31
...Spring, 32...Ball, 33...Groove.

Claims (1)

[Claims] 1. To separate and collect crud as radioactive contaminants deposited in a fuel pool provided in a nuclear reactor facility for storing spent fuel by suctioning the crud together with water using a suction pump. In the method of removing solids using a filter device, the side surface communicates with the crust suction nozzle 1 via a hose 2, the bottom surface communicates with a solids storage container 5 via a lid 6 opened and closed by an air cylinder 16, and the top surface communicates with a strainer 4. A solid matter separator 3 includes a strainer box 15 that communicates with a pipe 12 that connects to a submersible pump 8 through the tube, and an air cylinder 21 is installed at the other end of a hose 9 that connects to the submersible pump 8.
socket 19 that can be attached and detached by
A filter device 10 equipped with a plug 22 connected to the fuel pool 11 was installed underwater in the fuel pool 11, and an operating valve, an instrument, a pressurizing device for the exhaust pressure system of the operating air, and a filter pressure alarm device were loaded. The operation panel is installed on the floor surface, and the removal of solid matter adhering to the strainer 4, storage in the container 5, and attachment/detachment/replacement of the filter device 10 are performed by remote control underwater. How to remove crud from a reactor fuel pool. 2 installed in the reactor fuel pool water, communicates with the clad suction nozzle 1 via a hose 2 on the side, communicates with the solids storage container 5 via a lid 6 opened and closed by an air cylinder 16 on the bottom, and communicates with the solids storage container 5 on the top surface. A pipe 12 is connected to a submersible pump 8 via a strainer 4.
A solid separation device 3 consisting of a strainer box 15 communicating with a strainer 4 provided in the middle of a pipe 12, a submersible pump 7 for backwashing, and a socket removably attached to the other end of a hose 9 connected to the submersible pump 8 with an air cylinder 21. 19, a filter device 10 with a plug 22 connected to the socket 19 on the top, an operating valve instrument installed on the floor, a pressurizing device for the operating air exhaust system, and a filter pressure alarm device. A crud removal device for a nuclear reactor fuel pool, characterized by comprising a controlled operation panel.