Patent Number: 
Section: claims

1. A cask comprising:a cask body having a tubular shape with a central axis as a center and capable of housing a fuel assembly;a tubular outer cylinder surrounding said cask body;a plurality of fins aligned in a circumferential direction in a tubular space formed between said cask body and said outer cylinder, and connecting an outer peripheral surface of said cask body and an inner peripheral surface of said outer cylinder to divide said tubular space into a plurality of divided spaces; anda plurality of neutron shields containing a neutron shielding material with which said plurality of divided spaces is filled, whereineach neutron shield includes:a molded pipe portion including a hollow portion that is a void portion that extends in an axial direction along said central axis; anda filled portion serving as the neutron shielding material with which a space between said molded pipe portion and an outer edge of a divided space is filled, andsaid void portion is surrounded by a neutron shielding material forming said molded pipe portion. 2. The cask according to claim 1, whereinsaid molded pipe portion is formed of a molded member of a neutron shielding material. 3. The cask according to claim 1, whereinsaid molded pipe portion includes:a first precast member disposed on one side of said void portion in a section perpendicular to said axial direction; anda second precast member disposed on the other side of said void portion in said section and joined to said first precast member to surround said void portion with said first precast member. 4. The cask according to claim 3, whereina joint between said first precast member and said second precast member has a labyrinth structure. 5. The cask according to claim 1, whereinsaid void portion has a shape extending in said circumferential direction in a section perpendicular to said axial direction. 6. A cask comprising:a cask body having a tubular shape with a central axis as a center and capable of housing a fuel assembly;a tubular outer cylinder surrounding said cask body;a plurality of fins aligned in a circumferential direction in a tubular space formed between said cask body and said outer cylinder, and connecting an outer peripheral surface of said cask body and an inner peripheral surface of said outer cylinder to divide said tubular space into a plurality of divided spaces; anda plurality of neutron shields containing a neutron shielding material with which said plurality of divided spaces is filled, whereineach neutron shield includes:a molded pipe portion including a hollow portion that is a void portion that extends in an axial direction along said central axis; anda filled portion serving as the neutron shielding material with which a space between said molded pipe portion and an outer edge of a divided space is filled, andsaid molded pipe portion is surrounded by the neutron shielding material of said filled portion. 7. A method of producing a neutron shield in a cask,said cask including:a cask body having a tubular shape with a central axis as a center and capable of housing a fuel assembly;a tubular outer cylinder surrounding said cask body; anda plurality of fins aligned in a circumferential direction in a tubular space formed between said cask body and said outer cylinder, and connecting an outer peripheral surface of said cask body and an inner peripheral surface of said outer cylinder to divide said tubular space into a plurality of divided spaces,the method of producing said neutron shield, comprising:disposing a molded pipe portion in a divided space, said molded pipe portion including a hollow portion that is a void portion extending in an axial direction along said central axis; andforming a filled portion by filling a space between said molded pipe portion and an outer edge of said divided space with a neutron shielding material with fluidity and hardening said neutron shielding material, whereinsaid void portion is surrounded by a neutron shielding material forming said molded pipe portion.