JPH0672950B2 - How to replace the lip seal in a storage container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a storage container for storing and transporting a large amount of radioactive substances, toxic substances to the human body, etc. The present invention relates to a method of replacing a lip seal attached between a lid and a container lid.

<Prior Art> As such a storage container, for example, one having a ring member screwed around a top opening of a bottomed container body made of stainless steel with a bolt is generally used. There is. A sealing material called a lip seal made of a silicon-based organic material (for example, silicon rubber) or soft vinyl chloride is fitted in the groove formed on the inner peripheral edge of the ring member.

The opening of this storage container is closed by a container lid.
That is, in order to attach the container lid to the opening of the storage container, usually, a plurality of inner protruding protrusions provided on the inner periphery of the ring member and a plurality of outer protruding protrusions provided on the outer periphery of the container lid are relatively disposed. It is carried out by rotating and fitting in the circumferential direction, and by the rotation in the opposite direction, both are separated.
The airtightness between both members is maintained by the lip seal provided between them.

The radioactive substances such as plutonium and uranium mixed oxides and the toxic substances to the human body are usually placed in and out of this storage container with the opening of this storage container joined to the opening of the glove box isolated from the external environment. Be seen.

That is, a flange is provided on the periphery of the opening (usually closed by a cover) for fitting the storage container formed in the base plate of the glove box. Then, the inner peripheral surface of the flange and the outer peripheral surface of the ring member at the opening of the storage container are engaged with each other by a fitting structure similar to the above which can be engaged and disengaged by rotating in the circumferential direction, and the both are joined.

In this joined state, the container lid is in a state of being overlapped with the cover that closes the opening of the glove box, and in this state, both are removed together in the glove box. Next, the radioactive substance or the like provided in the glove box is stored in the storage container, and thereafter, the storage container is separated from the glove box in a state of being sealed by the container lid by a means reverse to the above.

<Problems to be Solved by the Invention> By the way, the above-mentioned lip seal gradually deteriorates due to rotational sliding in the circumferential direction when the container lid is attached and detached to cause pain, or a substance to be put into and taken out of the container is In the case of a fine powder nuclear fuel material, there is a problem that the fine powder adheres to the lip seal and is difficult to remove.

Therefore, when the storage container is used for a long period of time, it is necessary to replace them. Further, when the container lid, the O-ring, etc. provided at the opening of the storage container are contaminated or damaged, the replacement of them is also required.

In the replacement work of this lip seal, etc., it is required to reliably control the contamination of nuclear materials, but when the internal volume of the storage container is large, the entire inner surface of the storage container including the lip seal is contaminated. It is extremely difficult to replace the lip seal etc. safely and with good workability without exposing the part, and at present, no effective replacement method has been developed, and the entire storage container should be discarded or stored for a long time. Has become.

The present invention provides a lip seal that can replace a lip seal or the like attached to the inner circumference of an opening of a storage container safely and with good workability without releasing a contaminated portion on the inner surface of the storage container for radioactive substances, toxic substances, and the like. It is intended to provide a method of replacing a seal.

<Means for Solving the Problems> A method for replacing a lip seal according to the present invention is a storage container for storing and transporting a large amount of radioactive substances, toxic substances to the human body, etc. that cannot be handled in an open state. Is a method of replacing a lip seal attached between the inner peripheral edge of the opening and the container lid, wherein the container lid is first removed in a state where the opening of the storage container is joined to the opening of the first glove box, In addition, the opening is closed by a temporary lid member provided in the first glove box, and the inner surface of the opening including the surface of the temporary lid member and at least the surface of the container lid on the opening side are dried. After coating with a paint that can be peeled off later, the first step of closing the opening with the container lid and the first step with the opening of the second glove box are completed. In a state where the opening of the obtained storage container is joined, first, the container lid is removed, and after replacing the lip seal attached to the container lid, a second step of sealing the opening with the container lid, In a state in which the opening of the storage container that has finished the second step is joined to the opening of the first glove box,
First, the container lid is removed, then the temporary lid material is removed from the opening, the coating material remaining on the inner surface of the opening is peeled off, and then the opening is sealed with the container lid. The point is to have.

Further, for example, in a structure in which the opening of the 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 separated from each other in the second step. If the paint is kept in an undried state until it is removed together with the lip seal provided therebetween, the container lid, the ring member, etc. are separated from the storage container in the second glove box. In this case, it is possible to effectively prevent the spread of contamination from the cut-off portion.

Furthermore, in the second step, consumables such as an O-ring attached to the container lid may be replaced with the replacement of the lip seal, and the container lid and the ring member may be decontaminated. You can

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

Furthermore, a paint that uses water as a diluent as this paint,
That is, when the water-soluble paint is used, the storage container is moved from the first glove box to the second glove box and before the container lid is removed from the storage container in the second glove box. Unlike other paints that use volatile solvents, the internal pressure inside the storage container does not rise due to volatile substances, so that the radioactive substances and toxic substances inside the storage container are not exposed to the outside of the storage container. It becomes possible to prevent the scattering more reliably.

<Operation> As described above, by attaching the temporary lid member 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 the paint that can be peeled off after drying, the second glove is provided. It is possible to prevent the contamination level from rising when the container lid is cut off in the box.

Therefore, the second glove box can be managed at a very low contamination density, and therefore the measures for preventing contamination in the glove box can be simplified, and the work efficiency required for replacing the lip seal and the like can be improved.

Further, since contamination of ring members and container lids other than the consumable items removed in the second glove box can be completely decontaminated, it is possible to reuse those that can be used if decontaminated. .

And since the lip seals (lip seals, container lids, ring members, O-rings, etc.) can be replaced safely and reliably in this way, the storage container can be maintained, and therefore the storage container can be used for a long period of time. Can improve economic efficiency.

<Examples> Examples of the case where the present invention uses a double cover system will be described below.

In FIG. 1 (A), the storage container 1, which cannot be used due to contamination of the lip seal or the like, is first attached to the opening provided in the first glove box 2 as indicated by arrow A. That is, with the container lid 4 of the storage container 1 fitted to the facility opening cover (cell door) 3 that is a cover attached to the opening of the first glove box 2, the storage container 2 is rotated,
The lids are connected to each other by the fitting structure.

Next, by a lid handling machine (not shown) provided inside the first glove box 2, the facility opening lid 3 and the container lid 4 together, and a ring member fixed to the top opening of the storage container 1 with a bolt or the like. 9 and separate them from the inside of the first glove box 2 as shown by arrow B.

After that, a temporary lid member (bang) 5 is attached to the inside of the opening of the storage container 1 as shown by an arrow C to prevent the spread of contamination from the inside of the storage container. That is, by tightening the metal plates provided on the upper and lower sides of the temporary lid member 5 with the central thumbscrew, the elastic member arranged on the outer peripheral portion is expanded in the circumferential direction and pressed against the inner periphery of the opening of the storage container, This opening is closed by the temporary lid 5.

Next, as indicated by arrow D, at least the surface of the container lid 4 that faces the inner surface of the storage container, the surface of the temporary lid member 5 that faces the inside of the first glove box 2, and the storage container 1 and the ring member 9. The water-soluble paint 6 that can be peeled off after drying is applied to the inner peripheral surface of the above in a thickness of about 0.2 to 0.5 mm to cover these surfaces.

Then, while the water-soluble paint 6 is in an undried state, the facility opening lid 3 and the container lid 4 are attached to the ring member 9 as indicated by arrow E, and then the storage container 1 is rotated with respect to the first glove box 2. Then, the storage container 1 and the container lid 4 are separated from the first glove box 2 as shown by an arrow F. Details of the opening of the storage container 1 in the state in which the temporary lid member 5 is attached and the water-soluble paint 6 is applied are as shown in FIG. 2, and the chain line in the figure indicates the application surface of the water-soluble paint. Is.

As described above, the storage container 1 that has undergone the steps in the first glove box 2 is placed in the second glove box 7 having an opening whose inner diameter is equal to or larger than the outer diameter of the ring member 9 as indicated by an arrow G. Connect by a fitting structure. In the figure, reference numeral 8 is an O-ring that is pressed between the extension of the outer periphery of the opening of the storage container 1 and the opening of the second glove box 7.

In this second glove box 7, the container lid 4, the ring member 9, the lip seal 10 for sealing between the container lid 4 and the ring member 9, and the O-ring 11 etc. are integrally removed as shown by an arrow H. Then, it is separated from the storage container 1.

At the time of this separation, it is important that the water-soluble paint 6 is in a non-dried state. That is, since the water-soluble paint 6 is not dried, the water-soluble paint 6 applied to the inner peripheral surface of the ring member 9 and the inner peripheral surface of the storage container 1 when the container lid 4 and the ring member 9 are separated. Can be cut cleanly at these boundaries. As a result, the pollution is prevented from scattering from the boundary to the inside of the second glove box 7, that is, the occurrence of the pollution from the boundary is prevented and the spread of the pollution of the second glove box 7 can be completely prevented. it can.

The container lid 4, the ring member 9, the lip seal 10, the O-ring 11 and the like removed from the storage container 1 in this way are routed through the holes provided in the second glove box 7 in the path indicated by the arrow I. It is transferred into the decontamination glove box 12 shown in FIG. 1 (B), and the internal decontamination devices 13 to 15 are indicated by arrows J to L.
Decontamination is performed by washing in. In addition, if the item cannot be decontaminated or cannot be reused, it is discarded, for example, along the path indicated by arrow M and replaced with a new item.

The container lid 4, the ring member 9, the O-ring 11, etc., which have been decontaminated or replaced in this way, are transferred from the decontamination glove box 12 as indicated by arrow N, and are combined with a new lip seal 16 at arrow O. After that, it is transferred again into the second glove box 7 as indicated by the arrow P, and is attached to the opening of the storage container 1 inside the second glove box 7 as indicated by the arrow Q.

The storage container 1 for which the lip seal has been exchanged as described above is reconnected to the first glove box 7 through the paths indicated by the arrows R and S, and the facility opening lid 3 and the container lid 4 are attached to the first glove box 2. , The facility opening lid 3 and the container lid 4 are integrally separated from the ring member 9 as indicated by the arrow T and pulled out into the first glove box 2.

At this stage, the water-soluble paint 6 applied to the opening of the storage container 1 and the like is dry. Then, the water-soluble paint 6 remaining in the opening of the storage container and the like other than the peeling in the decontamination step is peeled and removed, and the temporary lid is opened from the inside of the opening of the storage container 1 as indicated by an arrow U. The material 5 is removed.

After that, the facility opening lid 3 and the container lid 4 are attached again as shown by the arrow V, and then the storage container 1 together with the container lid 4 is removed from the first glove box 2, and the series of operations is completed.

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 the contamination level from rising when the container lid or the like is cut off in the second glove box. The box can be managed at a very low pollution density, and the measures for preventing pollution in this glove box are simplified, and therefore the work efficiency required for replacement of the lip seal and the like can be improved.

In this way, it is possible to safely and reliably replace the lip seal or other related parts or decontaminate, and the storage container can be maintained. There is an effect that it can be achieved.

[Brief description of drawings]

FIGS. 1 (A) and 1 (B) are explanatory views of each step in the embodiment, and FIG. 2 shows a state in which the opening of the storage container is closed by the container lid after the temporary lid member is mounted in the storage container. FIG. 1 ... storage container, 2 ... first glove box, 4 ...
… Container lid, 5 …… Temporary lid material, 6 …… Water-soluble paint, 7 …… Second glove box, 8,11 …… O ring, 9 …… Ring member, 10 …… Lip seal.

Claims (5)

[Claims] 1. A storage container for storing and transporting a large amount of radioactive substances, toxic substances to the human body, and the like that cannot be handled in an open state, and a lip seal attached between the inner peripheral edge of the opening of the storage container and the container lid. In the method of exchanging the first glove box, the container lid is first removed in a state where the opening of the storage container is joined to the opening of the first glove box, and the temporary lid material provided in the first glove box is used. The opening is closed, 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 side of the opening are coated with a paint that can be peeled after drying, and then the container lid is used. First, in the state where the first step of sealing the opening and the opening of the storage container that has finished the first step are joined to the opening of the second glove box, first the container lid is closed. After removing and replacing the lip seal attached to the container lid, the second step of sealing the opening with the container lid and the second step of opening the opening of the first glove box are completed. With the opening of the storage container joined, first remove the container lid, then remove the temporary lid material from the opening, and further peel off the paint remaining on the inner surface of the opening, etc. A method for replacing a lip seal in a storage container, comprising a third step of sealing a part with the container lid. 2. A ring member is attached to the periphery of the opening of the storage container, and the opening is sealed by attaching the container lid to the ring member, and these rings are used in the second step. The method according to claim 1, wherein the coating material is kept in an undried state until the member and the container lid are removed together with the lip seal provided between them. 3. The replacement method according to claim 1, wherein in the second step, a consumable item such as an O-ring attached to the container lid is replaced. 4. The 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.