Radiation shielding vessel

A boundary between each of inner and outer cylinders, and a lead shielding material of a radiation shielding vessel is made uneven, as well as the thickness of the lead shielding material at the concave portion and that at the convex portion is made identical. As effective surface area of the boundary is increased compared with the case of a flat surface with no unevenness, to increase the area of thermal conduction at the boundary between the inner and the outer cylinders, and the lead shielding material, and naturally improve the thermal conductivity. In addition, since the thickness of the lead shielding material at the concave portion and that at the convex portion are substantially identical, the shielding property of the lead shielding material is made uniform with no positional difference, and the thermal conduction is also made uniform. If a gas having good thermal conduction such as a helium gas is sealed to the gap of the boundary between the inner and outer cylinders, and the lead shielding material, the thermal conductivity at the boundary can be increased to improve the heat releasing property. In addition, it can be manufactured relatively efficiently and easily without complicating steps as in a case of homogenization treatment. (I.S.)