JPH02264896A - Method of exchanging lip seal in storage vessel - Google Patents

Abstract

PURPOSE:To heighten safety to contrive the improvement of work efficiency by attaching a temporary cover material to the opening part of a storage vessel and coating the inner face and the like of the opening part of the storage vessel with separable paint after drying. CONSTITUTION:A vessel cover 4 is taken off in a condition to join the opening part of a storage vessel 1 to the opening part of a glove box 2 to close the opening part with the use of a temporary cover material 5 provided in the box 2. After the inner face of the opening part and the surface and the like of the cover 4 are coated with separable water soluble paint 6 after drying, they are closed. Next, the vessel 1 integrated with the cover 1 is separated from the box 2 to connect to a glove box 7 to remove the cover 4, a lip seal 10 and the like as the paint remains undried to perform necessary decontamination, exchange and the like so as to attach them to the vessel 1. Thereafter, the vessel 1 is connected to the box 2 again to peel off dried paint 6 to remove the temporary cover material so as to separate from the box 2. Accordingly, the seal 10 can be exchanged for a new one without the opening of any inner face contamination part caused by a substance and the like of radioactivity and toxicity.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a storage container for storing and transporting a large amount of radioactive substances and substances toxic to the human body that cannot be handled in an open state. The present invention relates to a method for replacing a lip seal installed between a container lid and a container lid.

<Prior Art> Generally, such a storage container is constructed by, for example, a bottomed container body made of stainless steel, with a ring member screwed around the top opening by bolts. There is. A sealing material called a lip seal made of a silicon-based organic material (for example, silicone rubber), soft vinyl chloride, or the like is fitted into a groove formed on the inner peripheral edge of the ring member.

The opening of this storage container is sealed with a container lid.

That is, when attaching the container lid to the opening of the storage container, normally, the plurality of inner protrusions provided on the inner periphery of the ring member and the plurality of outer protrusions provided on the outer periphery of the container lid are relatively connected. This is done by rotating in the circumferential direction to fit together, and the structure is such that both are separated by rotating in the opposite direction.

The lip seal provided between these members maintains airtightness between both members.

Radioactive materials such as plutonium and uranium mixed oxides, as well as substances toxic to the human body, are normally taken in and out of this storage container by connecting the opening of the storage container to the opening of a glove box that is isolated from the outside world. be exposed.

That is, a flange is provided around the periphery of an opening (usually closed by a cover) for fitting a storage container formed in the base plate of the glove box. Then, the inner circumferential surface of the flange and the outer circumferential surface of the ring member at the opening of the storage container are engaged with each other by a fitting structure similar to that described above, which can be engaged and detached by rotation in the circumferential direction, thereby joining the two.

In this joined state, the container lid and the cover that closes the glove box opening are in an overlapping state, and in this state they can be removed together into the glove box. Next, the radioactive substances and the like provided in the glove box are stored in the storage container, and then the storage container is removed from the glove box while being sealed by the container lid by means opposite to those described above.

<Problems to be Solved by the Invention> By the way, the above-mentioned lip seal gradually deteriorates and causes pain as it rotates and slides in the circumferential direction when the container lid is attached and detached, or the lip seal may become damaged due to the movement of the lip seal in the circumferential direction when the container lid is attached or removed. In the case of finely powdered nuclear fuel material, there is a problem in that the fine powder adheres to the lip seal and is difficult to remove.

Therefore, if storage containers are used for a long period of time, they must be replaced. Furthermore, if the container lid, O-ring, etc. provided at the opening of the storage container become contaminated or damaged, they will also need to be replaced.

When replacing lip seals, etc., it is necessary to reliably control contamination from nuclear materials, etc. However, in cases where the internal volume of the storage container is large, contamination of the entire inner surface of the storage container, including the lip seal, must be ensured. It is extremely difficult to replace lip seals etc. safely and efficiently without exposing the parts, and as of now no effective replacement method has been developed, and the entire storage container must be discarded or stored for a long time. It becomes.

This invention provides a lip seal that can safely and efficiently replace a lip seal attached to the inner periphery of the opening of a storage container without releasing the contaminated inner surface of the storage container for radioactive substances, toxic substances, etc. The purpose is to provide a method for replacing seals.

Means for Solving the Problems> A method for replacing a lip seal according to the present invention is a method for replacing a lip seal in a storage container for storing and transporting a large amount of radioactive substances or substances toxic to the human body that cannot be handled in an open state. A method for replacing a lip seal installed between an inner peripheral edge of an opening of a first glove box and a container lid, the method includes first removing the container lid with the opening 58 of the storage container connected to the opening of a first glove box. , also this first
The opening is closed by a temporary lid provided in the glove box, and the inner surface of the opening including the surface of the temporary lid and at least the surface of the container lid on the opening side are removable after drying. A first step of sealing the opening with the container lid after coating with paint; and a state in which the opening of the storage container that has completed the first step is joined to the opening of a second glove box. a second step of first removing the container lid and replacing the lip seal attached to the container lid, and then sealing the opening with the container lid; After step 2 has been completed, with the opening of the storage container joined,
A third step of first removing the container lid, then removing the temporary lid material from the opening, peeling off the paint remaining on the inner surface of the opening, and then sealing the opening with the container lid. The gist is that it has the following.

Further, for example, in a structure in which the opening of the storage container is sealed by attaching the container lid to a ring member attached around the opening of the storage container, the ring member and the container lid are attached in the second step. If the paint is kept in an undried state until it is removed together with the lip seal provided in between, the container lid, ring member, etc. can be separated from the storage container in the second glove box. This can effectively prevent the spread of contamination from the separated portion at the time of separation.

Furthermore, in the second step, in addition to replacing the lip seal, consumables such as an O-ring attached to the container lid may be replaced, and contaminants such as the container lid and the ring member may be removed. You can also do it.

Moreover, as the paint that can be peeled off after drying, for example, polyvinyl butyral paint or acrylic paint can be used.

Furthermore, this paint uses water as a diluent,
In other words, when using a water-soluble paint, between moving the storage container from the first glove box to the second glove box and removing the lid etc. from the storage container in the second glove box, Unlike other paints that use volatile solvents, the pressure inside the sealed storage container does not increase due to volatile substances, and therefore radioactive and toxic substances inside the storage container are not scattered to the outside of the storage container. It becomes possible to prevent this more reliably.

As described above, by attaching a temporary lid to the opening of the storage container in the first glove box and coating the inner surface of the opening of the storage container with a paint that can be peeled off after drying, the second glove box is installed. It is possible to prevent the contamination level from increasing when the container lid etc. are separated inside the glove box.

For this reason, the second glove box can be managed with a very low contamination density, which simplifies the measures to prevent contamination in this glove box, and also improves the work efficiency required for replacing lip seals and the like.

In addition, since the ring members and container lids other than the consumables removed in the second glove box can be completely decontaminated, it is possible to reuse the items that can be used once they are decontaminated. Become.

In this way, you can safely and reliably use lip seals, etc.
Lip seals, container lids, ring parts.

Since O-rings, etc.) can be replaced, maintenance of the storage container becomes possible, and therefore, the storage container can be used for a long period of time, thereby improving economic efficiency.

<Example> Below, an example will be described in which the present invention is implemented using a double cover system.

In FIG. 1(A), a storage container 1 which has become unusable due to contamination of the lip seal or the like is first attached to an opening provided in a first grow box 2 as indicated by arrow A. That is, with the container lid 4 of the storage container 1 aligned with the facility opening lid (cell door) 3, which is a cover attached to the opening of the first grow box 2, the storage container 2 is rotated to open these cells. The lids are connected to each other by the fitting structure.

Next, using a lid removing machine (not shown) installed inside the first grow box 2, the facility opening lid 3 and the container lid 4 are removed together with a ring member fixed to the top opening of the storage container 1 with bolts or the like. 9 and pull them out inside the first glow box 2 as shown by arrow B.

Thereafter, a temporary cover material (bang) 5 is attached to the inside of the opening of the storage container as shown by arrow C to prevent the spread of the medallion dye from inside the storage container. That is, by tightening the metal plates provided on the top and bottom of the temporary lid material 5 with the central thumbscrew, the elastic member disposed on the outer periphery expands in diameter in the circumferential direction and comes into pressure contact with the inner periphery of the opening of the storage container. This opening is closed by a temporary lid 5.

Next, as shown by the arrow, at least the surface of the container lid 4 facing the inner surface of the storage container, the surface of the temporary lid material 5 facing the inside of the first glove box 2, and the storage container 1 and the ring member 9. A water-soluble paint 6, which can be peeled off after drying, is applied to the inner circumferential surface, etc., to a thickness of about 0.2 to 0.5 fins to cover these surfaces.

Thereafter, while the water-soluble paint 6 is still wet, the facility opening lid 3 and container lid 4 are attached to the ring member 9 as shown by arrow E, and then the storage container 1 is rotated relative to the first glove box 2. Then, the storage container 1 and the container lid 4 are separated from the first glove box 2 in the direction of arrow F. The installation of the temporary lid 5 and the details of the opening of the storage container 1 after application of the water-soluble paint 6 are as shown in Figure 2, and the chain line in the figure indicates the application of the water-soluble paint. It is a surface.

The storage container 1 that has completed the process in the first glove box 2 as described above is transferred to the second glove box 7 having an opening with an inner diameter larger than the outer diameter of the ring member 9 as shown in the arrow G. Connect using a similar fitting structure. In the figure, reference numeral 8 denotes an O-ring that is pressed between the extending portion of the outer periphery of the opening of the storage container 1 and the opening of the second glow box 7.

In this second glove box 7, the container lid 4. Ring member 9. Lip seal 10 for sealing between container lid 4 and ring member 9. Also, the O-ring 11 and the like are removed together as shown by arrow H and separated from the storage container 1.

At the time of this separation, it is important that the water-soluble paint 6 is in an undried state. In other words, since the water-soluble paint 6 is not dry, when the container lid 4 and the ring member 9 are separated, the water-soluble paint applied to the inner circumferential surface of the ring part gap 9 and the inner circumferential surface of the storage container 1, respectively. 6 will be able to cut cleanly at these boundaries. And with this, from this boundary
This prevents the Q dye from scattering inside the second glove box 7, that is, the generation of contamination from this boundary is prevented, and the spread of contamination in the second glove box 7 can be completely prevented.

Container lid 4 removed from storage container 1 in this way. Ring member 9. The lip seal IO, O-ring 11, etc. are inserted through holes provided in the second glove box 7.
It is transferred along the path of arrow I into the decontamination glove box 12 shown in FIG. 1(B), and is decontaminated by cleaning or the like in internal decontamination devices 13 to 15 as shown by arrow JL.

Also, items that cannot be decontaminated or cannot be reused are discarded, for example, along the route of arrow M, and replaced with new items.

Container lids decontaminated or replaced in this way 4. Ring member 9. Alternatively, the O-ring 11 and the like are transferred from the decontamination glove box I2 as shown by arrow N, combined with a new lip seal 16 as shown by arrow 0, and then returned to the second glove box 7 as shown by arrow P. transferred,
It is attached to the opening of the storage container 1 as shown by arrow Q inside the second glove box 7 .

The storage container 1 in which the lip seal has been replaced as described above is connected again to the first glove box 7 along the routes shown by arrows R and S, and in the first glove box 2, the facility opening lid 3 and the container lid 4 are connected again. are connected, and furthermore, the facility opening lid 3 and the container lid 4 are separated as one from the ring member 9 as shown by the arrow T and pulled out into the first grow box 2.

Furthermore, at this stage, the water-soluble paint 6 applied to the opening of the storage container 1 is dry.

The water-soluble paint 6 remaining at the opening of the storage container, etc., other than those peeled off during the decontamination process, etc., is peeled off and removed. The material 5 is removed.

Thereafter, the facility opening lid 3 and the container lid 4 are attached again as indicated by the arrow V, and then the storage container 1 and the container M4 are removed from the first glove box 2, thereby completing the series of operations.

Note that the storage container whose lip seal has been replaced in this way is returned to the process and reused.

<Effects of the Invention> As described above, according to the replacement method of the present invention, it is possible to prevent an increase in the contamination level when separating the container lid etc. in the second glove box. Since the box can be managed at a very low contamination density, measures to prevent contamination in the glove box can be easily taken, and therefore work efficiency required for replacing lip seals and the like can be improved.

In this way, the lip seal can be replaced or other related parts can be replaced or decontaminated safely and reliably, and the storage container can be maintained, making it possible to use the storage container for a long time and improving economic efficiency. It has the following effects:

[Brief explanation of drawings]

Figures 1 (A) and (B) are explanatory diagrams of each process in the example, and Figure 2 shows the state in which the opening of the storage container is sealed with the container lid after the temporary lid material has been attached to the storage container. It is an explanatory diagram. DESCRIPTION OF SYMBOLS 1... Storage container, 2... First glove box, 4... Container lid, 5... Vi lid material, 6... Water-soluble paint, 7... Second glove box , 8, 11...
・0 ring, 9...Ring member, 10...Lip seal.

Claims (1)

[Scope of Claims] 1. In a storage container for storing and transporting a large amount of radioactive substances or substances toxic to the human body that cannot be handled in an open state, it is installed between the inner periphery of the opening of the storage container and the container lid. In this method of replacing a lip seal, first, with the opening of the storage container joined to the opening of the first glove box, the container lid is removed, and the temporary lip seal installed in the first glove box is removed. After closing the opening with a lid material and coating the inner surface of the opening including the surface of the temporary lid material and at least the surface of the container lid on the opening side with a paint that can be peeled off after drying, the container is closed. a first step of sealing the opening with a lid; and with the opening of the storage container that has completed the first step joined to the opening of the second glove box, first removing the container lid; and a second step of sealing the opening with the container lid after replacing the lip seal attached to the container lid; and a second step of sealing the opening with the container lid; With the opening of the container joined, first remove the container lid, then remove the temporary lid material from the opening, peel off the paint remaining on the inner surface of the opening, and then close the opening. A method for replacing a lip seal in a storage container, comprising a third step of sealing the container with the container lid. 2. A ring member is attached around the opening of the storage container, and the opening is sealed by attaching the container lid to this ring member, and in the second step, these ring members and the container are 2. The replacement method according to claim 1, wherein the paint is kept undried until the lid is removed together with the rib seal provided between them. 3. In the second step, the O attached to the container lid is removed.
The replacement method according to claim 1, characterized in that a consumable item such as a ring is replaced. 4. The replacement method according to claim 1, wherein in the second step, the container lid and the like are decontaminated. 5. The replacement method according to claim 1, wherein a water-soluble paint is used as the paint.