JPH0713672B2 - Plutonium raw material transport container - Google Patents

Description

TECHNICAL FIELD The present invention relates to a container for conveying plutonium raw material powder. More specifically, the present invention relates to a transport container having a structure in which an plutonium raw material is filled in an annular space between an outer cylinder portion having outward fins and an inner cylinder portion having inward fins.

[Prior Art] Plutonium generates heat of 10 to 15 W / kg PuO _{2 when it} decays. Therefore, PuO ₂ powder and PuO ₂ -UO ₂ mixed powder (MOX powder)
When the product is placed in a container and transported or stored, the temperature of the powder in the container rises.

Therefore, in the prior art, heat dissipation is achieved by providing outward and inward fins on the container wall of the cylindrical container body. That is, the heat generated from the powder was transferred to the vessel wall by the fins inside the container, and was further radiated by the fins outside.

[Problems to be Solved by the Invention] However, this structure does not sufficiently dissipate heat, and there is a possibility that the UO ₂ powder in the MOX powder may be oxidized particularly because the temperature at the center of the container rises too much. An example of the relationship between the conventional container structure and the internal temperature is shown in FIG. In the figure, reference numeral 10 indicates the container body, reference numeral 12 indicates the internal fins, and reference numeral 14 indicates the raw material powder. The external fins are omitted in the figure. The temperature distribution in the central portion (in the area indicated by the imaginary line a) where the internal fins 12 are not present in the container can be calculated by approximating with a cylindrical model. When the calculated result and the measured value are combined, the result shown in the same figure is obtained. Thus, the core temperature reaches 160 ° C., and the above-mentioned problem of powder oxidation occurs.

Further, in the conventional structure, since the fins 12 are present inside the container body, the adhesion of the powder is promoted, and the powder remains in the container at the time of discharging.

The object of the present invention is to eliminate the drawbacks of the prior art as described above, improve the heat dissipation efficiency and mitigate the powder temperature rise due to the plutonium decay heat, and convey the plutonium raw material such that no powder remains in the container during powder discharge. To provide a container.

[Means for Solving the Problems] In order to solve the above problems, the present invention adopts an annular structure in which the central portion of the container body is hollowed out as the basic structure of the plutonium raw material transport container. The container body includes an outer cylinder portion and an inner cylinder portion that are concentrically arranged, and an annular bottom portion that connects the both to the lower end. A large number of outer fins and inner fins project outward and inward from the outer surface and the inner surface of the outer tubular portion, respectively. Therefore, there are no fins inside the annular container body.

In the present invention, the plutonium raw material refers to a powder containing plutonium such as PuO ₂ powder or PuO ₂ -UO ₂ mixed powder.

[Operation] In a conventional cylindrical container such as the conventional one, the temperature becomes highest at the center. However, since the present invention has an annular container structure in which the central portion is hollowed out, the temperature distribution in the radial direction is divided into two, and since fins are also provided inside, the heat radiation efficiency is improved and the temperature peak is lowered.

Since there are no obstructive protruding parts such as fins in the container body, powder hardly remains in the container when the powder is discharged.

[Embodiment] FIGS. 1A and 1B show an embodiment of a plutonium raw material transport container according to the present invention, where A is a transverse sectional view and B is a longitudinal sectional view.

The transport container 20 basically has an annular shape with a hollowed central portion. That is, the container body 22 is composed of an outer cylinder portion 24 and an inner cylinder portion 26 that are concentrically arranged, and an annular bottom portion 28 that connects the both at the lower end. Here, the annular bottom portion 28 has an inclined surface with a lower inside and a higher outside. Then, a large number of outer fins 30 are provided to project radially outward from the outer surface of the outer tubular portion 24,
Further, a large number of inner fins 32 are provided so as to project radially inward from the inner surface of the inner tubular portion 26. Each outer fin 30 and inner fin 32
Are heights substantially corresponding to the heights of the outer cylinder portion 24 and the inner cylinder portion 26, respectively, and are arranged substantially uniformly over the entire circumference. Therefore, there are no fins inside the annular container body.

Further, a conical central top portion 34 is provided so as to cover the upper surface of the inner space of the inner tubular portion 26, and a truncated cone-shaped extension tubular portion 35 which is continuous with the upper end of the outer tubular portion 24 and whose upper end center is open. This opening 38
The diameter of is approximately equal to the diameter of the inner cylindrical portion 26. The conical central top 34 serves to prevent stacking during powder filling. In addition, the extension cylinder part 36 with a smaller upper end opening 38
It functions to distribute powder during filling and prevent dispersion during discharging.

In addition, gripping portions 40 for handling the container are provided at opposite positions outside the container body 22.

The plutonium raw material powder 14 is put in an annular space inside the container body 22. The plutonium raw material 14 is introduced from the relatively small opening 38 toward the central top portion 34, is distributed almost uniformly, and is filled in the annular space. The decay heat of plutonium is transmitted to the outer tubular portion 24 and the inner tubular portion 26, and is efficiently radiated by the outer fins 30 and the inner fins 32.
Since the annular bottom portion 28 is also inclined, it contributes to the improvement of heat dissipation.

As a result of using the conventional structure container and calculating it with the thermal calculation code "TRUMP", it is estimated that the powder temperature distribution in the container is as shown in FIG. From this, it is understood that the maximum powder temperature in the container can be suppressed to 120 ° C or lower.

[Advantages of the Invention] As described above, according to the present invention, since the container body has an annular structure in which the central portion is hollowed out, the temperature distribution in the radial direction is divided into two, and fins are provided on the outside and inside. Together, the heat radiation efficiency becomes high, and the rise of the powder temperature inside the container is moderated. Therefore, for example, oxidation of UO ₂ can be prevented.

Further, since no fins are provided inside the annular container body filled with the powder, the residual powder in the container at the time of discharging the powder can be significantly reduced.

[Brief description of drawings]

1A and 1B are horizontal and vertical sectional views showing an embodiment of the plutonium raw material transport container according to the present invention, FIG. 2 is an explanatory view of the structure and temperature distribution of the product of the present invention, and FIG. It is an explanatory view of a structure of goods and temperature distribution. 14 ... Plutonium raw material, 20 ... Transport container, 22 ... Container body, 24 ... Outer cylinder part, 26 ... Inner cylinder part, 28 ... Annular bottom part,
30 …… Outer fin, 32 …… Inner fin, 34 …… Center top, 36 …… Extension cylinder.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-96897 (JP, A) Actual flat 1-70199 (JP, U) Actual flat 1-97298 (JP, U)

Claims (2)

[Claims] Claim: What is claimed is: 1. An annular container main body comprising an outer cylinder portion and an inner cylinder portion arranged concentrically, and an annular bottom portion having a lower end continuous between the outer cylinder portion and the outer cylinder portion, and protruding only outward from the outer cylinder portion. A transport container for plutonium raw material, comprising a large number of outer fins and a large number of inner fins projecting only inward from an inner cylindrical portion. 2. A cone-shaped central top portion that covers the upper surface of the inner cylinder portion, and a truncated cone-shaped extension cylinder portion that is continuous with the upper end of the outer cylinder portion and has an opening at the center of the upper end, and the annular bottom portion is an inclined surface. The transport container according to claim 1, wherein