Patent Number: 
Section: claims

1. A storage container for storing a closed container having a radioactive substance sealed therein, comprising: a container body having a storage portion for storing the closed container and a top opening through which the closed container is loaded into and unloaded from the storage portion;  a lid closing the top opening of the container body;  a heat removing portion having intake vents in a bottom portion of the container body, exhaust vents in a top portion of the container body, and a cooling air passage defined between an inner surface of the storage portion and an outer surface of the closed container stored in the storage portion, the heat removing portion being configured to cause air introduced into the container body through the intake vents to flow into the cooling air passage so as to remove heat from the radioactive substance, and discharge the air through the exhaust vents;  closing members configured to close the intake vents and exhaust vents as the closed container is loaded into and unloaded from the storage portion; and  a speed reducing portion provided at the top opening of the container body and having a through hole through which the closed container can be passed, the through hole having a dimension smaller than the dimension of the storage portion and larger than the outside dimension of the closed container. 2. A storage container according to  claim 1 , wherein the speed reducing portion is removably fitted to the top opening of the container body. claim 1 3. A storage container according to  claim 1 , wherein the speed reducing portion is formed integrally with the container body. claim 1 4. A storage container according to  claim 1 , wherein the speed reducing portion has a groove formed on the inner surface of the through hole so as to be substantially coaxial with the through hole. claim 1 5. A storage container according to  claim 1 , wherein each of the closing members is removably attached to the container body. claim 1 6. A storage container according to  claim 1 , wherein each of the closing members is attached to the container body to be movable between a position in which the closing member closes the intake vent or exhaust vent and a position in which the closing member opens the intake vent or exhaust vent. claim 1 7. A storage container according to  claim 1 , wherein the container body is formed of concrete. claim 1 8. A storage container refilling system for loading a closed container having a radioactive substance sealed therein into and unloading the closed container from a storage container, which comprises a container body having a storage portion for storing the closed container and a top opening through which the closed container is loaded into and unloaded from the storage portion, a lid closing the top opening of the container body, and a heat removing portion having intake vents in the bottom portion of the container body, exhaust vents in the top portion of the container body, and a cooling air passage defined between an inner surface of the storage portion and an outer surface of the closed container stored in the storage portion, the heat removing portion being configured to cause air introduced into the container body through the intake vents to flow into the cooling air passage so as to remove heat from the radioactive substance, and discharge the heat through the exhaust vents, the storage container refilling system comprising: a reduction cylinder having an outside dimension smaller than the dimension of the storage portion and an inside dimension larger than the dimension of the closed container and configured to be loaded into the storage portion through the top opening;  a first lift mechanism configured to raise and lower the reduction cylinder between a down position in which the reduction cylinder is set in the storage portion of the container body and an up position such that the reduction cylinder is drawn out of the storage portion; and  a second lift mechanism having a holding portion for holding one end portion of the closed container and configured to raise and lower the closed container with respect to the container body,  the second lift mechanism being configured to load into and unload the closed container from the storage portion of the container body with the reduction cylinder set in the storage portion. 9. A storage container refilling system according to  claim 8 , which further comprises a container stage portion in which the storage container and a transportation container for storing and transporting the closed container are arranged side by side, and wherein the second lift mechanism is movable between a first position over the transportation container and a second position over the storage container. claim 8 10. A storage container refilling system according to  claim 9 , which further comprises a housing overlying the container stage portion and movable between a first position opposite the transportation container and a second position opposite the storage container, the first and second lift mechanisms being provided in the housing, the housing having an inlet opening, adapted to be opposed to a top opening of the transportation container in the first position and opposed to the top opening of the storage container in the second position and capable of being penetrated by the reduction cylinder and the closed container, and a shutter portion for opening and closing the inlet opening and configured to store the reduction cylinder pulled up by means of the first lift mechanism and the closed container pulled up by means of the second lift mechanism. claim 9 11. A storage container refilling system according to  claim 8 , wherein the reduction cylinder has a bottom opening adapted to be closed by the bottom wall of the container body in the down position and a top opening situated above the exhaust vents of the container body. claim 8 12. A storage container refilling method for loading a closed container having a radioactive substance sealed therein into and unloading the closed container from a storage container, which comprises a container body having a storage portion for storing the closed container and a top opening through which the closed container is loaded into and unloaded from the storage portion, a lid closing the top opening of the container body, and a heat removing portion having intake vents in the bottom portion of the container body, exhaust vents in the top portion of the container body, and a cooling air passage defined between the inner surface of the storage portion and the outer surface of the closed container stored in the storage portion, the heat removing portion being configured to cause air introduced into the container body through the intake vents to flow into the cooling air passage so as to remove heat from the radioactive substance, and discharge the heat through the exhaust vents, the storage container refilling method comprising: loading a reduction cylinder, having an outside dimension smaller than the dimension of the storage portion and an inside dimension larger than the dimension of the closed container, into the storage portion through the top opening of the storage container;  inserting the closed container into the reduction cylinder from above through the top opening of the reduction cylinder, thereby locating the closed container in the storage portion;  pulling up the reduction cylinder from the storage portion after locating the closed container in the storage portion; and  unloading the closed container from the storage portion in a manner such that the closed container is pulled up from the storage portion after the reduction cylinder is loaded into the storage portion through the top opening of the storage container and located outside the closed container.