Patent ID: 7194060

Claim:
A cask comprising: a body configured to house a basket having a plurality of cells configured to receive spent fuel assemblies; a plurality of heat conductive fins provided around an external periphery of the body; an external cylinder fixed to an external periphery of the heat conductive fins; and a neutron absorber provided in a space defined by the body, the heat conductive fins, and the external cylinder, wherein the external cylinder comprises a plurality of first and second belt members, and wherein a plurality of units are arranged at predetermined intervals and have a T-shaped cross section, which includes first welds connecting the external periphery of the heat conductive fins and the first belt members along an approximately central part of the first belt members, wherein second welds connect an internal periphery of the heat conductive fins to the body, wherein the first and second belt members are disposed apart from the body forming the space therebetween, and the second belt members cover a gap between the first belt members of adjacent units and third welds connecting the second belt member and the first belt members of adjacent units are provided on outer edges thereof.