JPH0530157Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention] This invention relates to a water level adjustment mechanism for a spent fuel transportation container, and more specifically, for transporting nuclear fuel used in a nuclear power plant reactor, etc. to a reprocessing plant. This relates to a water level adjustment mechanism for a spent fuel transport container.

[Prior art]

Generally, spent nuclear fuel generated in a nuclear reactor is accompanied by radiation and heat, so for safety reasons it is stored in a pool containing cooling water.

If necessary, a spent fuel transport container (hereinafter referred to as a transport container) consisting of a container body and a lid is placed in this pool, and after storing nuclear fuel and cooling water and setting the lid, it is removed from the pool. Take it out.

By the way, the temperature of the water inside the transport container rises due to the heat generated by the nuclear fuel during transport, causing the water to expand. Therefore, the amount of water in the transport container that is taken out of the pool prior to transport must be extracted in a designed amount. There is.

Conventionally, a water level adjustment valve system and a water level gauge system have been proposed as this water level adjustment mechanism. The former is, as shown in FIG. 3, a transport container 3 consisting of a container body 1 and a lid 2, in which the container body 1 is provided with a drain portion 4 as a drain port and a vent portion 5 as an air intake port. Water level adjustment valve 6 in its predetermined position
However, in this case, since the water level adjustment valve 6 is provided in the container body 1, strict requirements are placed on the water level adjustment valve 6 due to the need for strong thermal safety (accident conditions) of the transportation container 3. Design conditions will be imposed.

On the other hand, in the latter case, as shown in FIG. 4, a water level gauge 7 is provided in the drain part 4 provided at the bottom of the container body 1.
In reality, the height of the transport container reaches 4 to 5 m, so the water level gauge 7 is necessarily long and, as a result, expensive. In addition, there were other problems such as difficulty in handling.

In addition, as a water level adjustment mechanism other than the above,
No. 59-122599 discloses that the lid of the container body is provided with a first communication passage that is opened and closed by a first valve body, and a second communication passage that is opened and closed by a second valve body.
A cooling water level adjustment device for a spent nuclear fuel transport container, in which a water level adjustment pipe communicating with a communication passage is extended to a predetermined position within the container body, the first communication passage is an air intake port, and the second communication passage is an outlet. is proposed.

By the way, from the viewpoint of preventing cooling water leakage accidents and improving safety, it is necessary to design the spent nuclear fuel transport container to have as few openings as possible, but according to the device in the above publication, Since the first communication passage and the second communication passage are formed separately in the lid, it is necessary to open two through holes in the lid, and this conventional transport container is still not sufficiently safe. It could not be said that it was secured.

Furthermore, in order to completely shield radiation, a high level of processing precision is naturally required for this through-hole, so forming through-holes in two locations on the lid as described above requires additional manufacturing costs. There was a problem with it being too bulky.

[Purpose of invention]

In view of the above-mentioned problems, the present invention eliminates the need to form a through hole in only one place in the lid of a transport container in order to adjust the water level of cooling water. Compared to the one with holes,
In addition to ensuring higher safety,
The purpose of the present invention is to provide a water level adjustment mechanism for a spent fuel transport container that is capable of reducing the cost required for processing through-holes, has relatively relaxed design conditions for the transport container, is inexpensive, and is easy to handle. That is.

[Summary of the idea]

To achieve the above object, the water level adjustment mechanism for a spent fuel transportation container of the present invention includes a container body that accommodates spent nuclear fuel and cooling water for cooling the spent nuclear fuel, and a mechanism that is attached to and detached from the opening of the container body. In a transportation container, the container body is provided with a drain part capable of draining the cooling water at the bottom of the container body, and one of the lids has an opening at a predetermined water level in the container body. It becomes a drainage outlet,
This structure is characterized by providing a water level regulator with a double pipe structure consisting of an inner cylinder and an outer cylinder that accommodates the inner cylinder, the other of which serves as an air intake port that opens above the drainage port. .

[Example] Next, referring to FIGS. 1 and 2, the water level adjustment mechanism of the spent fuel transport container of the present invention is constructed by installing a drain part 4 at the bottom as shown in FIGS. 3 and 4. An example in which the present invention is applied to a container body 1 consisting of a transport container 3 and a lid 2 will be described.

Note that in FIGS. 1 and 2, the same reference numerals as in FIGS. 3 and 4 indicate the same names.

FIG. 1 is an enlarged sectional view of a main part of a first embodiment of the present invention, in which an air intake port 12 and a drain port 13 are provided coaxially on a lid body 2 constituting a transportation container.

That is, the water level regulator 14 is composed of a double pipe, and the inner pipe 15 penetrates a hole 16 provided in the lid body 2, extends to a predetermined water level WL in the container body, and is connected to the drain port 1.
Formed as 3. The lower end of the outer cylinder 17 is a cover 19 that fits into a recess 18 provided in the lid body 2.
is attached to and formed as an air intake port 12.

Note that 20 is a bolt for attaching the cover 19 to the lid body 2, and 21 is an O-ring for maintaining airtightness.

In this embodiment, the transport container 3 taken out of the pool is almost completely filled with cooling water, but by sending pressurized air into the transport container 3 through the air inlet 12 and the hole 16, the cooling water in the transport container 3 is discharged from the drain outlet 13 in the inner cylinder 15.

Then, the discharge of the cooling water corresponding to the overflow amount set in anticipation of thermal expansion is completed, and the drain port 1
With air coming out from container 3, the water level in transport container 3 can be adjusted to a predetermined water level WL.

In this way, by providing the air intake port 12 and the drain port 13 on the same axis, only one hole 16 can be formed in the lid body 2, which improves safety compared to the conventional type. can be improved.

Note that instead of feeding pressurized air from the air intake port 12, cooling water may be sucked out from the drain port 13.

FIG. 2 is an enlarged cross-sectional view of the main part of the second embodiment of the present invention, in which the air intake port 1 is similar to the first embodiment.
2 and the drain port 13 on the same axis, there is only one hole 16 formed in the lid 2 for adjusting the level of cooling water.

The water level regulator 22 in this case is composed of an outer cylinder 23 and an inner cylinder 24, with the inside of the outer cylinder 23 serving as the drain port 13, and the inside of the inner cylinder 24 serving as the air intake port 12.

[Effect of idea]

The water level adjustment mechanism of the spent fuel transport container of the present invention includes a container body that accommodates spent nuclear fuel and cooling water for cooling the spent nuclear fuel, and a lid body that is removably installed at the opening of the container body. In the transportation container, a drain portion capable of discharging the cooling water is provided at the bottom of the container body, and one of the lids is provided with a drain port that opens to a predetermined water level in the container body, and the other is a drain port that opens to a predetermined water level in the container body. It is characterized by a water level regulator with a double pipe structure consisting of an inner cylinder and an outer cylinder that accommodates this inner cylinder, which serves as an air intake port that opens above the drainage port, so that the following effects can be achieved. can be played.

The water level regulator consists of a combination of an air intake port and a drain port provided on the lid of the transport container, and has a double pipe structure, with one of the inner cylinder and the outer cylinder housing this inner cylinder serving as the air intake port. By making the other side a drain port,
Since only one hole can be formed in the lid, safety can be greatly improved compared to the conventional case where holes are formed in two places.

In addition, since the air intake and drainage ports necessary for water level adjustment are both provided on the lid, the design requirements for the transport container are relatively relaxed, and it is possible to downsize and reduce processing costs.
It can be inexpensive and easy to handle.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main part of the water level adjustment mechanism of the spent fuel transport container in the first embodiment of the present invention,
The figure is a sectional view of a main part of a water level adjustment mechanism for a spent fuel transport container in a second embodiment of the present invention, and FIGS. 3 and 4 are schematic sectional views of a conventional water level adjustment mechanism for a spent fuel transport container. . DESCRIPTION OF SYMBOLS 1... Container body, 2... Lid, 3... Transport container, 4... Drain part, 12... Air intake port, 13
...Drain port, 14...Water level regulator, 15...Inner cylinder, 17...Outer cylinder, 22...Water level regulator, 23...
...outer cylinder, 24...inner cylinder.

Claims (1)

[Scope of utility model registration request] A transport container consisting of a container body that accommodates spent nuclear fuel and cooling water for cooling the spent nuclear fuel, and a lid that is removably attached to the opening of the container body, the cooling water is provided at the bottom of the container body. In addition to providing a drain portion that can drain water, one of the lids serves as a drain port that opens to a predetermined water level within the container body, and the other serves as an air intake port that opens above this drain port. A water level adjustment mechanism for a spent fuel transport container, characterized in that it is provided with a water level regulator having a double pipe structure consisting of an inner cylinder and an outer cylinder that accommodates the inner cylinder.