Transportation container for plutonium raw material

In a cylindrical vessel conventionally used, there is a worry that temperature is highest at the central portion and UO2 powders in MOX powders are oxidized. Then, in the present invention, an annular structure that the central portion of a vessel main body is perforated is adopted. The vessel main body comprises an outer cylinder and an inner cylinder coaxially disposed and an annular bottom connecting both of them at the lower end. Then, a great number of outer fins and inner fins are protruded from the outer surface and the inner surface of the external cylinder outward and inward respectively. Accordingly, there are no fins at all in the annular container main body. With such a constitution, since the radial temperature distribution is divided into two regions, and fins are disposed at the outer and the inner sides, the heat radiation efficiency is increased, and the elevation of temperature of powders at the inside of the vessel is moderated. (T.M.)