Patent Number: 
Section: claims

1. A cask comprising: a barrel body having an integrated forged structure, the barrel body shielding gamma rays, the barrel body having an inner and outer wall;  a shielding member provided outside the outer wall of said barrel body, the shielding member shielding neutrons and having an inner wall; and  a basket having an angular cross section and a cellular structure, the cellular structure including cells each being formed with pipes having a square cross section, the pipes absorbing neutrons and said barrel body contacting the outer wall of said basket;  wherein substantially all of the outer wall of the basket is shaped so as to correspond with and contact the inner surface of said barrel body; and the inner wall of said shielding member contacts the outer wall of said barrel body, and  wherein used fuel assemblies are accommodatible and storable in the cells. 2. The cask according to  claim 1 , wherein the cellular structure of the basket has plane sections and step-like sections, and claim 1 a portion of the outer shape of the barrel body corresponding to the step-like sections of the basket is parallel to a line that connects the vertices of the step-like sections of the basket. 3. The cask according to  claim 2 , wherein adjacent pipes of the cells contact one another, and claim 2 wherein the basket is in contact with the barrel body. 4. The cask according to  claim 3 , claim 3 wherein the barrel body has a cavity formed therein and wherein an internal shape of the cavity in the barrel body corresponds with an outer shape of the angular cross section of the basket,  the barrel body having an external shape having a plurality of corners and sides, wherein at least some of the sides of the barrel body are parallel to a line which connects vertices of an angular cross section of the basket. 5. The cask according to  claim 4 , wherein the shielding member is formed on an outside surface of the barrel body, and the shielding member has a uniform thickness. claim 4 6. The cask according to  claim 2 , claim 2 wherein the barrel body has a cavity formed therein and wherein an internal shape of the cavity in the barrel body corresponds with an outer shape of an angular cross section of the basket,  the barrel body having an external shape having a plurality of corners and sides, wherein at least some sides of the barrel body are parallel to a line which connects the vertices of the angular cross section of the basket. 7. The cask according to  claim 2 , wherein the shielding member has a shape corresponding to a shape formed when vertices of the angular cross section of the basket are connected. claim 2 8. The cask according to  claim 1 , wherein an outer shape of the barrel body corresponds to a shape formed when vertices of the angular cross section of the basket are connected by providing a chamfer in a part thereof where the thickness thereof is sufficient to shield gamma rays in the barrel body. claim 1 9. The cask according to  claim 8 , wherein adjacent pipes of the cells contact one another, and claim 8 wherein the basket is in contact with the barrel body. 10. The cask according to  claim 9 , claim 9 wherein an internal shape of a cavity in the barrel body corresponds with an outer shape of the angular cross section of the basket,  the barrel body having an external shape having a plurality of corners and sides, wherein at least some sides of the barrel body are parallel to a line which connects vertices of an angular cross section of the basket. 11. The cask according to  claim 10 , wherein the shielding member is formed on an outside surface of the barrel body, and the shielding member has a uniform thickness. claim 10 12. The cask according to  claim 8 , claim 8 wherein an internal shape of a cavity in the barrel body corresponds with an outer shape of an angular cross section of the basket,  the barrel body having an external shape having a plurality of corners and sides, wherein at least some of the sides of the barrel body are parallel to a line which connects the vertices of the angular cross section of the basket. 13. The cask according to  claim 8 , wherein the shape of the shielding member corresponds to the shape formed when the vertices of the angular cross section of the basket are connected. claim 8 14. The cask according to  claim 1 , which comprises an outer casing positioned outside the shielding member and at least partially contacting the shielding member such that spaces are formed between said chamfered portions of the shielding member and the outer casing for reducing the thickness of the shielding member at the chamfered portions. claim 1 15. A cask comprising; a barrel body having an integrated forged structure, the barrel body shielding gamma rays, the barrel body having a uniform thickness and having an inner and outer wall;  a shielding member provided outside the barrel body, the shielding member shielding neutrons and having chamfered portions; and  a basket having an angular cross section and a cellular structure, the cellular structure including cells each being formed with pipes having a square cross section, the pipes absorbing neutrons and said barrel body contacting an outer wall of said basket;  wherein substantially all of the outer shape of the barrel body correspondswith a shape formed when the vertices of the angular cross section of the basket are connected such tat the basket is uniformly spaced from an inner surface of the shielding member,  wherein used fuel assemblies are accommodatible and storable in the cells, spaces are formed between said chamfered portions of the shielding member and the outer casing for reducing the thickness of the shielding member at the chamfered portions and wherein at least a part of the outer wall of the basket is shaped so as to correspond with and contact the inner surface of said barrel body and the inner wall of said shielding member contacts the outer wall of said barrel body.