Patent Number: 
Section: claims

1. A laser welding apparatus for spacer grid of nuclear fuel assembly, comprising:a base frame including a chamber installment hole, a guide rail installed along the chamber installment hole, and a damper arranged in an end of the guide rail;a welding chamber unit assembled with the base frame in guidance by the guide rail and equipped with an operable door in front and a glass window at the top to be airtight;a laser welding unit mounted on the base frame for radiating laser through the glass window to weld spacer grid in the welding chamber unit; anda locking member for fixing the welding chamber unit on the base frame,wherein the locking member comprises:a locking block protruding from a bottom of the welding chamber unit;a locking arm arranged so as to be pivoted to the base frame to support the locking block, the locking arm including a first wing and a second wing which respectively extend in different directions from a pivoting center, the first wing including a convex surface; anda locking pin mounted on the base frame for restricting rotation of the locking arm,wherein the damper restricts movement of the welding chamber unit toward the damper along the guide rail, andwherein the welding chamber unit is fixed on the base frame, such that the welding chamber unit is located adjacent to the damper with the movement of the welding chamber toward the damper being restricted and the damper facing a left side of the locking block, the locking arm, which has been rotated in a first direction, comes in contact with a right side of the locking block with the convex surface of the first wing being in direct contact with the locking block, and the locking pin comes in direct contact with the second wing and restricts the locking arm from further rotating in the first direction. 2. The welding apparatus for spacer grid of nuclear fuel assembly according to claim 1, wherein the base frame further comprises a glass cover prepared to cover the glass window. 3. The welding apparatus for spacer grid of nuclear fuel assembly according to claim 2, wherein a ventilation hole interconnected with the welding chamber unit is formed in a flange to which the glass window is fixed, and the flange is characterized by a ventilation valve arranged in the flange and controlled to be opened or closed by the glass cover. 4. The welding apparatus for spacer grid of nuclear fuel assembly according to claim 1, wherein the welding chamber unit comprises a position detecting unit for detecting the standard position of a driving pad which rotates a welding rotation plate in which the spacer grid is settled, and outputting an electrical detection signal. 5. The welding apparatus for spacer grid of nuclear fuel assembly according to claim 1, the locking member further comprises a handle bar protruding from the locking arm in a rotation axis direction of the locking arm.