JPS5925479B2 - Sealing device for equipment inserted into the nuclear reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is used in nuclear reactor equipment, such as a fuel exchanger or
It relates to a sealing device for equipment inserted into a reactor, such as a damaged fuel inspection machine.

When the furnace-inserted equipment is inserted into the furnace, it not only cuts off the atmosphere between the inside and outside of the furnace, but also when it is pulled out of the furnace from the furnace-inserted position, the equipment itself (hereinafter simply referred to as "
It is necessary to reliably prevent the liquid metal in the furnace, which is used as a primary coolant, from scattering into the surrounding atmosphere outside the furnace, adhering to the outer cylindrical part of the equipment There is.

Conventionally, equipment inserted into the reactor such as fuel exchangers and damaged fuel inspection equipment is different from equipment that moves in and out of the reactor while holding the fuel, such as fuel loading/unloading machines, in which only the equipment itself is moved in and out of the reactor. , they are generally not equipped with an airtight container to store the fuel suspended like a fuel loading/unloading machine.

For this reason, the conventional sealing structure for equipment inserted into the furnace is to install a door valve connected to the door valve on the furnace side at the lower end of a pedestal that suspends and supports the equipment body.
A shaft sealing mechanism is connected to the upper part of the door valve and installed in the penetrating portion of the outer cylinder of the device body, forming a pressure boundary when inserted into the furnace.

Furthermore, in this case, for furnaces that use sodium as the primary coolant, the shaft sealing mechanism has a built-in scraper to remove IJium adhering to the peripheral surface of the shaft of the equipment body. It is configured to actively remove sodium.

However, no matter how the shaft sealing mechanism is configured to enhance its shaft sealing function, it is structurally impossible to completely wipe out the sodium, and in addition, repeated use can cause damage to the seal.
Of the activated sodium in the furnace that adhered to the outer cylinder surface of the equipment body due to mechanical wear of the scraper, trace amounts of sodium that could not be completely removed by the shaft seal mechanism The radiation passes through the reactor and comes into contact with the surrounding air outside the reactor, scattering radiation and causing radioactive contamination of the surrounding area.

In view of the above points, the present invention aims to provide a sealing device for equipment inserted into a reactor that can skillfully prevent radiation from scattering into the surrounding atmosphere outside the reactor by simply installing a simple mechanism. This purpose is achieved by the present invention, in which the shaft sealing mechanism and the outer cylindrical part of the equipment main body are separated from the surrounding atmosphere and hermetically enclosed, so as to straddle between the outer periphery of the shaft sealing mechanism and the top outer periphery of the equipment main body. This is achieved by constructing a bellows-type expandable and retractable sealing cover made of radioactive material, as well as a breathing gas container filled with inert gas and communicating with the inner space of the sealing cover. Ru.

Next, the configuration and operation of the present invention will be explained based on illustrated embodiments.

In Figures 1 and 2, 1 is a reactor vessel, 2 is a rotating plug, 3 is a reactor core, 4 is sodium as a primary coolant, 5 is an equipment insertion hole drilled in the rotating plug 2, and 6 is a rotating plug 2. This is the furnace side door valve installed at the top.

On the other hand, the furnace insertion device 7 includes a device body 8, a pedestal 9 that suspends and supports the device body 8, a lifting drive device 10, a door valve 11 installed at the bottom end of the pedestal, and a shaft seal connected to the top of the door valve 11. It consists of a mechanism 12 and, in particular, a sealing cover 13, which is additionally installed according to the invention.

Further, the main body 8 includes an elongated outer cylindrical portion 8b extending downward from the top portion 8a housing the main components, and is suspended from the above-mentioned lifting drive device 10 via a wire rope 14.

The outer cylindrical portion 8b of the device main body 8 passes through the shaft sealing mechanism 12 and the first
It is moved up and down as shown by arrow A between the in-furnace insertion position shown in the figure and the out-of-furnace pull-out position shown in FIG.

Note that the opening and closing operations of the door valve 6.11 as the main body of the device moves up and down are well known, and will not be described here.

Further, the detailed structure of the shaft sealing mechanism 12 is as shown in FIG.

That is, on the inner peripheral surface of the shaft sealing case 16 housed inside the outer cylinder 15 connected to the upper part of the door valve 11, there is a gasket 17 that comes into contact with the peripheral surface of the outer cylinder part 8b of the device main body, and the sodium is wiped off. A gasket 18 for removing sodium and a scraper 19 for scraping off sodium are provided.

The sealing cover 13 is configured as a bellows-type expandable structure made of, for example, a radiation-resistant rubber material.

This bellows structure is expandable and foldable in the vertical direction as shown by arrow B, and each joint is provided with a core wire 20 in combination as shown in FIG.

Such a sealing cover 13 is an outer cylinder 15 in the shaft sealing mechanism 12.
It is also installed across flanges 21 and 22 which are attached to extend outward from the top 8a of the main body 8 of the device.

With this structure, the sealing cover 13 connects the outer cylindrical portion 8b of the device body 8 and the shaft sealing mechanism 12 to the inner space 1 of the sealing cover 13.
It is enclosed in a sealed manner in 3a to isolate and shield it from the surrounding atmosphere.

Furthermore, according to the present invention, the inner space 13a of the sealing cover 13
A breathing gas container 24 is installed via a hose 23 connected to the lower flange 21 so as to communicate with the lower flange 21.

The gas container 24 may be attached to the pedestal 9 of the equipment inserted into the furnace as shown, or may be placed separately from the equipment 7.

Sealed space 1 inside the gas container 24 and the sealed cover 13
An inert gas 25 such as argon is sealed inside 3a.

In the above configuration, when inserted into the furnace as shown in FIG. 1, the sealing cover 13 is folded, and most of the sealed gas is recovered from inside the sealing cover 13 through the hose 23 into the gas container 24.

When the device main body 8 is pulled up from the state shown in FIG. 1 as shown in FIG. 2, the sealing cover 13 is stretched along with this movement.

In this case, the volume of the inner space 13a increases and inert gas is replenished from the gas container 24.

In this way, inert gas breathing is performed between the sealing cover 13 and the gas container 24.

Note that the pressure of the sealed inert gas and the internal volume of the gas container 24 are appropriately determined in consideration of changes in the internal volume due to expansion and contraction of the sealing cover 13 and the pressure resistance strength of the sealing cover.

As is clear from the above description, according to the sealing device according to the present invention, the shaft sealing mechanism and the outer cylindrical part of the equipment main body are always activated when the equipment main body is raised or lowered, regardless of whether the equipment is inserted into the furnace or pulled out. It is enclosed within a sealed cover that expands and contracts with the flow of air, and is completely isolated and shielded from the surrounding atmosphere.

Moreover, the inert gas sealed within the sealing cover only moves between the gas container and the gas container, and does not leak outward.

As a result, when the equipment body is pulled out of the furnace, even if a trace amount of activated sodium remains that cannot be completely removed by the shaft sealing mechanism and passes through the shaft sealing mechanism while adhering to the outer cylinder of the equipment body. , it is possible to reliably prevent this from scattering into the surrounding atmosphere, thereby improving the reliability of radiation management.

Moreover, the entire equipment inserted into the furnace is housed in a large shielding container□
It is possible to provide a sealing device for equipment inserted into a furnace, which has a simple structure and can be manufactured at low cost, and has high practical value compared to a configuration in which the equipment is housed in a furnace.

[Brief explanation of drawings]

Each figure relates to an embodiment of the present invention, and FIGS. 1 and 2 are overall configuration diagrams showing the insertion and withdrawal states of the equipment inserted into the furnace, respectively, and FIG. FIG. 4 is an enlarged sectional view of the coupling portion, and FIG. 4 is an enlarged sectional view of the shaft sealing mechanism portion. 1... Furnace vessel, 2... Rotating plug, 6
... Furnace side door valve, 7 ... Furnace insertion device, 8 ... Furnace insertion device main body, 8a ...
...Top part, 8b...Outer cylinder part, 9...Base, 11...Door valve, 12...Shaft seal mechanism, 13...・Sealing cover, 13a...
...Inner space, 23...Communication hose, 24...
... Gas container, 25 ... Inert gas sealed, A ... Lifting direction of the device body, B ...
・Direction of expansion and contraction of the sealing cover.

Claims (1)

[Claims] 1. A door valve installed at the lower end of a pedestal that suspends and supports the main body of the equipment inserted into the furnace so that the outer cylinder part of the equipment main body can move up and down, a shaft sealing mechanism connected to the upper part of the door valve, the shaft sealing mechanism and the equipment inserted into the furnace. A bellows-type bellows-type device made of radiation-resistant material is installed across the outer periphery of the shaft sealing mechanism and the outer periphery of the top of the main body of the equipment inserted into the furnace, so as to isolate and seal the outer cylinder part of the main body from the surrounding atmosphere. 1. A sealing device for equipment inserted into a nuclear reactor, comprising a retractable sealing cover and a breathing gas container filled with an inert gas and communicating with an inner space of the sealing cover.