| 摘要 |
PURPOSE: To avoid the occurrence of surface wear at a specific area after a longterm use by enabling a control rod rotate around a center axis and fixing it at several positions for a carrier. CONSTITUTION: In a control rod assembly 1, each control rod 2 is inserted into a hole 3 of a spider-type carrier 4, and a buffer material is provided at a shoulder 5 of the control rod 2 and is brought into contact with a bosom part 6 of the carrier 4. Also, a screw is provided at the edge part of the control rod 2 for retaining a nut 7, and the nut 7 is clamped to a peak 8 of the carrier 4 for fixing the control rod 2. Further, a coupler 9 is provided at the center of the carrier 4 for retaining a drive shaft for moving the control rod 2 in vertical direction, and a groove 11 is formed at the bottom part 6, thus engaging a protrusion provided at the shoulder 5. Then, the nut 7 is removed at a certain time interval and the control rod 2 is moved down along the direction of a guide pipe and the control rod 2 is rotated and moved and then is fixed by the nut 7 again, thus preventing the control rod from being worn out and extending life and then reducing a nuclear waste.
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