JPH0830758B2 - Nuclear fuel shipping container - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transportation container for transporting nuclear fuel.

(Prior Art) Nuclear fuel is usually manufactured at a fuel manufacturing plant and then transported to a nuclear power plant. However, due to the nature of the fuel, strict control is required, and from the viewpoint of safety from accidents such as dropping and collision. Shipping containers are used.

This shipping container is required by law to protect the nuclear fuel contained therein even under the following test conditions in view of the recent recognition of safety.

(1) Drop test from 9 m (2) Drop test from 1 m onto a rod (3) Fire resistance test (800 ° C, 30 minutes) Then, as a design of a transportation container that satisfies the above conditions,
As shown in FIG. 4, a container body (1) and a lid body (2) which is openably and closably attached to the body body (1) have a double shell structure of an outer shell (3) and an inner shell (4), and Heat-insulating cushioning material (5)
In the illustrated example, an arc-shaped clamp (6) for laterally fixing two fuel assemblies is housed inside the transportation container.

By the way, as a joint structure for joining the lid body (2) and the main body (1) in the above-mentioned transport container, as shown in FIG. 5, they are joined together without a gap, and the O-ring (9) is interposed between the bolt (7). In the case of a structure that engages with a combined body such as a nut (8), the impact force at the time of the drop test is directly transmitted to the combined body, and not only is it easily damaged, but the outer shell is 800
However, since the inner shell is kept at a low temperature due to the effect of a heat insulating material, there is a problem that the joint is changed due to a temperature difference between the inner shell and the outer shell, and this thermal strain damages the bolt.

Then, in order to absorb the above deformation, if the O-ring (9) is enlarged and a gap (1) is opened in the joint surface as shown in FIG. 6, high temperature air is directly exposed to the O-ring (9) during the fire resistance test.
At the same time, it burns immediately, and the airtightness inside cannot be maintained. This naturally has a negative effect on the nuclear fuel contained.

In addition, regarding the shipping container as described above,
The publication discloses forming a projecting edge along the inner side of the joint surface, but this joint portion forms the joint portion of the container main body and the lid body with each other, and the No attempt is made to prevent the inflow of hot air.

(Problems to be Solved by the Invention) In view of the above situation, the present invention naturally provides a gap in the joint to absorb the deformation of the joint due to the temperature difference between the inner and outer shells, but further covers the gap. The purpose is to prevent the inflow of high temperature air from the gap by providing the protrusions and using the elastic airtight member in a double manner, and at the same time, to extend the combustion time to the inner side and enhance the strength and performance of the transportation container. To do.

(Means for Solving the Problems) That is, the feature of the present invention that meets the above-mentioned object is that a container for transporting a nuclear fuel in which a lid having a double shell is openably and closably attached to a container body having a double shell. In (1), a gap is formed in the joint between the container body and the lid, and a protrusion is provided along the outside of the joint surface of the joint to continuously cover the gap.

In this case, it is preferable to further mount a double elastic airtight holding member on the joint surface.

It is also preferable and effective to provide a projection continuously covering the gap along the inside of the joint surface.

(Operation) By constructing the joint portion structure between the container body and the lid of the transport container as described above, first, since a gap is provided in the joint portion, during the fire resistance test, the joint due to the temperature difference between the inner and outer shells is used. The O-ring in the gap has a function of absorbing a shock at the time of a drop test and protecting the combined body while absorbing the deformation of the portion.

Providing a protrusion that continuously covers the gap along the outside of the joint surface prevents the inflow of high temperature air from the gap and even if the protrusion receives a force such that the container body and the lid slip during the drop test. It resists this and maintains the strength of the container.

Further, the elastic airtightness holding member is doubled, and by providing a projection also covering the gap inside, the time for burning up to the inner O-ring is extended, and the inner airtightness holding ability is improved,
Prevents high-temperature air from flowing into the interior to increase safety.

(Example) Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an example of a joint structure according to the main part of the present invention,
In the figure, (1) shows a container body, (2) shows a lid,
Both of them have an outer shell (3) and an inner shell (4) as in the conventional container. Inside the inner and outer shells, for example, an alumina-silica-based heat insulating material is used for the body, and a balsa material is used for the end. It is filled with a heat insulating cushioning material, and is joined at a joint portion between them by a joint material such as a bolt (7) and a nut (8).

Then, a required gap (1) is formed between the container body (1) and the lid body (2) having the above-mentioned structure, and a packing (10) is formed on the outside.
A large O-ring (9) is provided on the inner side to double-hold the airtightness, and a protrusion (11) is formed on the inner side of the joint surface so as to continuously cover the gap (l). Inner protrusions (12) are respectively provided along the inner side of the.

In this case, in principle, the packing (10) is arranged over the entire circumference of the transportation container, but it is possible to achieve a certain purpose even if only the bolt portion is used.

Further, it is easiest to form the outer protrusion (11) by bending the outer edge portion as shown in the figure, but it is not particularly limited to this, and the inner protrusion (12) is also shown in FIG. The shape is not limited to the shape shown in Fig. 2, but the shape (a) may be formed by bending the upper end inward like the shape (b) as shown in FIG. Bending is more advantageous in terms of preventing the inflow of hot gas.

However, in any case, it is effective to cover the entire gap (l) in both the outer protrusion (11) and the inner protrusion (12).

By the way, in the structure shown in FIG. 1, the joint surface between the container body (1) and the lid body (2) is almost smooth, but this joint surface has a step (13) as shown in FIG. The surface may be provided, and in this case, it is preferable that the O-ring (9) is fitted into the recess (14) as shown in the figure.

Thus, according to the present invention, a gap is formed in the joint portion, and projections are provided on the outside or both inside and outside to cover the gap, and the elastic airtight holding material is double mounted. The nuclear fuel transportation container of is obtained.

(Effect of the Invention) As described above, the present invention continuously covers a gap along the outside of the joint surface between the container body and the lid body to which the openable / closable lid body is joined in the nuclear fuel transport container having the double shell. It has a special projection, and the container is made of double shell,
Since a gap is provided at the joint,
Absorbs thermal deformation due to outer shell temperature difference, and can keep the joint sound, such as bolts that stop the joint part together with the O-ring, etc., as well as the presence of external protrusions that cover the gap. This increases the resistance to the inflow of high-temperature air, prevents the O-ring from quickly becoming hot and burns, and maintains the airtightness of the container for a long time even in the fire resistance test. The effect of preventing can be expected.

Moreover, the elastic airtight holding member is double mounted on the joint surface, so that the time for burning up to the inner holding member, for example, the O-ring is further lengthened, and the effect of further extending the airtight holding time in the container is added.

In addition, by forming a protrusion on the inside as well, even if the O-ring burns, high temperature air inflow is further prevented, making it difficult for high temperature air to flow into the interior, and affecting the nuclear fuel contained in the container. Therefore, it is expected that the use of the transport container of the present invention as a whole will improve the safety of transporting nuclear fuels.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an example of a joint portion forming a main part of the transport container of the present invention, FIGS. 2 (a) and 2 (b) are explanatory views showing a modified example of an inner protrusion, and FIG. 3 is a book. FIG. 4 is a partial cross-sectional view showing a modified example of the joint portion forming the essential part of the invention, FIG. 4 is a schematic view showing the entire transport container, and FIGS. 5 and 6 are partial cross-sectional views showing a structural example of a conventional transport container joint portion. It is a figure. (1) …… Container body, (2) …… Lid body, (3) …… Outer shell, (4) …… Inner shell, (5) …… Insulation cushioning material, (7) …… Bolt, (8) ) …… Nut, (9) …… O ring, (10) …… Packing, (11) …… Outside projection, (12) …… Inside projection, (l) …… Gap.

Claims (3)

[Claims] 1. A nuclear fuel transportation container comprising a container body having a double shell and a lid body having a double shell structure attached to the body so as to be openable and closable, the lid body being joined to the container body. A nuclear fuel transport container characterized in that a gap is formed on the joint surface and a continuous protrusion is provided along the outside of the joint surface to cover the gap. 2. The nuclear fuel transportation container according to claim 1, wherein an elastic airtight holding member is doubly provided on a joint surface between the container body and the lid. 3. The nuclear fuel transport container according to claim 1, wherein the lid body is provided with a protrusion that continuously covers the gap along the inside of the joint surface that joins the container body.