Patent Number: 
Section: claims

1. A transport/storage cask for a radioactive material, comprising:an inner shell;an outer shell;a circular gamma ray shielding layer placed between said inner shell and said outer shell, said gamma ray shielding layer being formed by aligning a plurality of gamma ray shielding blocks composed of lead or a lead alloy in a block shape in the circumferential direction;a circular neutron shielding layer placed between said inner shell and said outer shell;a first metal member having a higher elasticity limit than the gamma ray shielding blocks and covering at least a part of each of the gamma ray shielding blocks; anda heat transmission fin formed of a thermally conductive material and extending to said outer shell, wherein said heat transmission fin does not contact said plurality of gamma ray shielding blocks. 2. The transport/storage cask for the radioactive material according to claim 1, whereinthe first metal member has a higher thermal conductivity than the gamma ray shielding blocks. 3. The transport/storage cask for the radioactive material according to claim 2, whereinthe first metal member is aluminum, an aluminum alloy, copper or a copper alloy. 4. The transport/storage cask for the radioactive material according to claim 1, whereina plurality of protruding portions for protruding into each of the gamma ray shielding blocks are formed on a cover surface serving as a surface of the first metal member opposing to each of the gamma ray shielding blocks. 5. The transport/storage cask for the radioactive material according to claim 1, whereina plurality of openings are formed in the first metal member, anda plurality of protrusions are formed in each of the gamma ray shielding blocks, at least a part of the protrusions being placed within the openings. 6. The transport/storage cask for the radioactive material according to claim 1, whereinthe first metal member has a section in a U shape. 7. The transport/storage cask for the radioactive material according to claim 6, whereinthe first metal member is arranged so that an opening part of the U shape is adjacent said inner shell. 8. The transport/storage cask for the radioactive material according to claim 1, whereineach of the gamma ray shielding blocks has an overlapping portion overlapping with other circumferentially neighboring gamma ray shielding block in the radial direction. 9. The transport/storage cask for the radioactive material according to claim 1, whereinsaid neutron shielding layer is composed of an organic material including hydrogen, and the organic material is a resin material or a rubber material. 10. The transport/storage cask for the radioactive material according to claim 1, whereinsaid neutron shielding layer is formed by aligning a plurality of neutron shielding blocks in a block shape. 11. The transport/storage cask for the radioactive material according to claim 10, whereinthe neutron shielding blocks are formed in a circular shape and arranged on an outer periphery of a plurality of the gamma ray shielding blocks. 12. The transport/storage cask for the radioactive material according to claim 10, whereinat least a part of each of the neutron shielding blocks is covered with a second metal member having a higher elasticity limit than the neutron shielding blocks. 13. The transport/storage cask for the radioactive material according to claim 12, whereinthe second metal member has a higher thermal conductivity than the neutron shielding blocks. 14. The transport/storage cask for the radioactive material according to claim 13, whereinthe second metal member is aluminum, an aluminum alloy, copper or a copper alloy. 15. The transport/storage cask for the radioactive material according to claim 12, whereinthe second metal member has a section in a U shape. 16. The transport/storage cask for the radioactive material according to claim 1, whereina gel material is coated over at least one of among a contact surface between said inner shell and said gamma ray shielding layer or the neutron shielding layer, a contact surface between said gamma ray shielding layer and said neutron shielding layer, and a contact surface between said outer shell and said gamma ray shielding layer or said neutron shielding layer. 17. The transport/storage cask for the radioactive material according to claim 16, whereinthe gel material is silicon or a silicon material. 18. The transport/storage cask for the radioactive material according to claim 1, whereina reinforcing material having a higher elasticity limit than the gamma ray shielding blocks is buried within each of the gamma ray shielding blocks. 19. The transport/storage cask for the radioactive material according to claim 1, wherein the heat transmission fin is L-shaped and includesa part extending from the inner shell to the outer shell; anda circumferentially extending part abutting the outer shell. 20. The transport/storage cask for the radioactive material according to claim 1, wherein the heat transmission fin contacts the first metal member.