Patent Number: 
Section: claims

1. A plasma welding apparatus for a guide thimble and guide thimble end plug of a nuclear fuel assembly, comprising:a welding chamber including:an end-plug inserting part into which the end plug is inserted and fixed,a guide-thimble inserting part which is provided on the same axis as the end-plug inserting part and into which the guide thimble is inserted and fixed,a torch assembling part to which a plasma welding torch is assembled so as to make a right angle with the end-plug inserting part and the guide-thimble inserting part, andargon inflow and outflow ports through which argon is supplied or discharged;an end-plug transfer unit supplying the end plug to the end-plug inserting part; anda guide-thimble transfer unit transferring the guide thimble to the guide-thimble inserting part,wherein the end-plug transfer unit and the guide-thimble transfer unit are respectively disposed at opposite sides of the welding chamber, andwherein the plasma welding torch welds the end plug to the guide thimble such that only one end of the guide thimble is closed, while another end of the guide thimble is maintained open. 2. The plasma welding apparatus set forth in claim 1, wherein the end-plug inserting part and the guide-thimble inserting part are provided so as to be able to rotate relative to the welding chamber, and are rotated by a driving motor. 3. The plasma welding apparatus set forth in claim 2, wherein the end-plug inserting part and the guide-thimble inserting part are assembled to the welding chamber via at least one bearing. 4. The plasma welding apparatus set forth in claim 1, wherein the argon inflow and outflow ports are configured so that argon is introduced at a lower portion of the welding chamber and is discharged to an upper portion of the welding chamber. 5. The plasma welding apparatus set forth in claim 1, wherein the guide-thimble inserting part includes a collet into which the guide thimble is inserted, a jig that horizontally moves along the collet in a forward/backward direction and provides the collet with a fastening force for fixing the guide thimble, and a lever operating the jig. 6. The plasma welding apparatus set for the in claim 1, further comprising:a sprocket installed on outer circumference of the end-plug inserting part; anda chain connected to the sprocket; anda driving motor which rotates the end-plug inserting part, the driving motor generating a driving force transferred via the chain and the sprocket to the end-plug inserting part. 7. The plasma welding apparatus set for the in claim 1, wherein the guide-thimble transfer unit includes:a guide-thimble transfer driver that loads and unloads the guide thimble toward and out of the welding chamber;a loading rail via which the guide thimble is loaded toward the welding chamber; andan unloading rail via which the guide thimble is unloaded out of the welding chamber, the unloading rail being separated from the loading rail. 8. The plasma welding apparatus set for the in claim 7, wherein the loading rail and the unloading rail are provided to have a slope in a direction perpendicular to a transferring direction of the guide thimble. 9. The plasma welding apparatus set for the in claim 1, wherein the plasma welding torch is movable upward from the argon inflow port.